This application claims the benefit of priority to the following Chinese patent applications, which are incorporated herein by reference in their entireties: Chinese Patent Application No. CN202311381406.4, filed October 23, 2023; Chinese Patent Application No. CN202410121595.X, filed January 29, 2024; Chinese Patent Application No. CN202411471244.8, filed October 21, 2024.This application is an entry into the European phase of International Patent Application No. PCT/CN2024/126657, published as WO 2025/087270.

The present disclosure relates to a lighting field, and more particularly to an LED filament and its application in an LED light bulb.

LED lighting fixtures possess numerous advantages such as long service life, compact size, high energy efficiency and power saving. Therefore, they have been widely applied in the market and gradually replace existing incandescent lamps and fluorescent lamps.

As one of the earliest electric lighting devices, tungsten filament lamps, a type of incandescent lamp, have evolved into one of the most well-received product forms among consumers owing to their long-term and large-scale application. However, due to limitations in manufacturing processes and raw materials, tungsten filament lamps feature low luminous efficiency, severe heat generation and high energy consumption, with an average service life of generally 1,000 to 3,000 hours. At present, LED lighting fixtures adopting LED filaments as light-emitting elements and designed to resemble tungsten filament lamps in appearance, also known as LED filament lamps, have emerged in the market. With superior luminous performance, low energy consumption, long service life and an appearance similar to tungsten filament lamps, such LED filament lamps have been rapidly accepted by consumers and quickly occupied the original market share and market position of tungsten filament lamps in the lighting industry.

An LED filament is an encapsulated light-emitting element formed by arranging and electrically connecting a plurality of LED chips in a predetermined direction, and conventional LED filaments are strip-shaped. To enable the LED filament to mimic the shape of a tungsten filament, the LED filament needs to be fabricated into a fine filament structure with an extremely small cross-sectional area. Such a structure inevitably faces challenges in structural strength; in particular, when the LED filament is flexible and needs to be bent, the LED filament itself or the internal conductive structure is prone to fracture, resulting in electrical disconnection and failure to light up.

In summary, in view of the deficiencies and drawbacks of the LED filament lamps in the prior art, how to design an LED filament lamp to avoid fracture thereof constitutes an urgent technical problem to be solved by those skilled in the art.

Numerous embodiments of the present invention are described in this abstract. However, the term "the present invention" is merely used to denote certain embodiments disclosed in the specification (whether or not covered by the claims), rather than serving as a complete description of all possible embodiments. The embodiments described above with respect to various features or aspects of the present invention may be combined in different manners to form an LED lamp or a part thereof.

According to another embodiment, an LED light bulb is provided. The LED light bulb comprises a lamp housing, a bulb base, a stem, two conductive supports, a driving circuit, and a flexible LED filament. The lamp housing has a central axis. The bulb base is connected to the lamp housing. The stem is disposed in the lamp housing along the central axis of the lamp housing. The two conductive supports are disposed in the lamp housing and have opposite polarities. The driving circuit is disposed in the bulb base and electrically connected to the two conductive supports. The flexible LED filament is disposed in the lamp housing and electrically connected to the two conductive supports. The flexible LED filament comprises an LED section, a first conductive electrode, a second conductive electrode, and a conductive portion. The LED section comprises a plurality of LED chips connected in series and a light conversion layer wrapping the plurality of LED chips. The first conductive electrode is disposed at one of two ends of the LED section and electrically connected to the plurality of LED chips and one of the two conductive supports, and a portion of the first conductive electrode is wrapped by the light conversion layer. The second conductive electrode is disposed at the other end of the LED section and electrically connected to the plurality of the LED chips and the other one of the two conductive supports, and a portion of the second conductive electrode is wrapped by the light conversion layer. The conductive portion is electrically connected between the plurality of LED chips. An LED chip among the plurality of LED chips has an electrical connecting portion, an end portion of the conductive portion is connected to the electrical connecting portion, the conductive portion has a first bent portion and a second bent portion, and the conductive portion extends from the electrical connecting portion along a first direction of the LED chip, extends toward a second direction of the LED chip through the first bent portion, and extends toward a third direction of the LED chip through the second bent portion, and wherein the first direction, the second direction, and the third direction are different directions.

In some embodiments, the first direction is a height direction of the LED chip, the second direction is a width direction of the LED chip, and the third direction is a length direction of the LED chip.

In some embodiments, a distance between the first bent portion and a surface of the LED chip is between 80 µm and 120 µm and a distance between the first bent portion and the second bent portion is between 100 µm and 120 µm.

In some embodiments, the LED filament further comprises a first solder layer, the first solder layer is made of a soldering material, and the end portion of the conductive portion is between the electrical connecting portion of the LED chip and the first solder layer.

In some embodiments, a projection area of the first solder layer on the electrical connecting portion of the LED chip is larger than a projection area of a bonding region of the conductive portion and the electrical connecting portion of the LED chip.

In some embodiments, the end portion of the conductive portion and the first solder layer together form a joining portion, the joining portion has a meshy surface, and a plurality of bulges and a plurality of indents are alternately arranged on the meshy surface.

In some embodiments, the LED filament comprises a second solder layer, the second solder layer is made of the solder material, and the end portion of the conductive portion is between the first solder layer and the second solder layer.

In some embodiments, each of a projection area of the first solder layer on the electrical connecting portion of the LED chip and a projection area of the second solder layer on the electrical connecting portion of the LED chip is larger than a projection area of a bonding region of the conductive portion, the first solder layer, and the second solder layer on the electrical connecting portion of the LED chip.

In some embodiments, a projection area of a bonding region of the conductive portion and the electrical connecting portion of the LED chip is smaller than the projection area of the first solder layer, and the projection area of the first solder layer is smaller than the projection area of the second solder layer.

In some embodiments, the plurality of LED chips further comprises a first row of LED chips and a second row of LED chips, the first row of LED chips and the second row of LED chips are connected in parallel, the LED chips of the first row of LED chips are connected in series, the LED chips of the second row of LED chips connected in series, and the first row of LED chips and the second row of LED chips are alternately arranged along a width direction of the LED filament.

In some embodiments, the LED filament further comprises a first conductive portion and a second conductive portion electrically connected between the LED chip and the first conductive electrode; wherein one of two ends of the first conductive portion is connected to the LED chip, the other end of the first conductive portion is connected to the first conductive electrode, one of two ends of the second conductive portion is connected to the first conductive electrode, and the other end of the second conductive portion is connected to the LED chip. The first conductive portion firstly extends downwards and then upwards by taking a first bending point of the first conductive portion as a first turning point of the first conductive portion, and the first conductive portion then extends upwards and then downwards by taking a second bending point of the first conductive portion as a second turning point of the first conductive portion; the second conductive portion firstly extends upwards and then downwards by taking a first bending point of the second conductive portion as a first turning point of the second conductive portion, and the second conductive portion then extend downwards and then upwards by taking a second bending point of the second conductive portion as a second turning point of the second conductive portion.

Other aspects and advantages of the present invention can be readily appreciated by those skilled in the art from the following detailed description. The following detailed description merely illustrates and describes exemplary embodiments of the present invention. As will be recognized by those skilled in the art, the disclosure of the present invention enables persons skilled in the art to make modifications to the specific disclosed embodiments without departing from the spirit and scope of the invention as defined herein. Accordingly, the accompanying drawings and the descriptions in the specification of the present invention are merely illustrative rather than restrictive.

The specific features of the invention as defined herein are set forth in the appended claims. The features and advantages of the present invention may be better understood with reference to the exemplary embodiments and the accompanying drawings described in detail below. The accompanying drawings are briefly described as follows:

• FIG. 1 is a partially perspective schematic view of the LED filament of the disclosure in an embodiment;
• FIG. 2 is a cross-sectional schematic view along line A-A in FIG. 1;
• FIG. 3 to FIG. 7 are schematic views of arrangements of the LED chips and the electrodes of the disclosure in different embodiments;
• FIG. 8 is a structural schematic view of the conductive portion of the disclosure in an embodiment;
• FIG. 9 is a structural schematic view of the second joining portion in related art;
• FIG. 10A is a structural schematic view of the ceramic capillary in related art;
• FIG. 10B is a cross-sectional structural schematic view of the ceramic capillary shown in FIG. 10A;
• FIG. 11A is a structural schematic view of the ceramic capillary of the disclosure in an embodiment;
• FIG. 11B is a cross-sectional structural schematic view of the ceramic capillary shown in FIG. 11A;
• FIG. 12 is a structural schematic view of the second joining portion of the disclosure in an embodiment;
• FIG. 13 is a structural schematic view of the ceramic capillary of the disclosure in an embodiment;
• FIG. 14 is a structural schematic view of the second joining portion of the disclosure in an embodiment;
• FIG. 15A to FIG. 15D are schematic view of the ceramic capillary having surfaces with two roughnesses of the disclosure in different embodiments;
• FIG. 16 is a structural schematic view of the second joining portion of the disclosure in an embodiment;
• FIG. 17A is a structural schematic view of the second joining portion of the disclosure in an embodiment;
• FIG. 17B is a cross-sectional structural schematic view of the second joining portion of the disclosure in FIG. 17A;
• FIG. 18A is a structural schematic view of the second joining portion of the disclosure in an embodiment;
• FIG. 18B is a cross-sectional structural schematic view of the second joining portion of the disclosure in FIG. 18A;
• FIG. 19A and FIG. 19B are schematic views of the cutting position of the second end of the conductive portion of the related art;
• FIG. 20 is a structural schematic view of the first joining portion of the related art;
• FIG. 21 is a structural schematic view of the first joining portion of the disclosure in an embodiment;
• FIG. 22A and FIG. 22B are partially schematic views of the first end of the conductive portion of the related art at different viewing angles;
• FIG. 23A and FIG. 23B are partially schematic views of the first end of the conductive portion of the disclosure in an embodiment;
• FIG. 24A and FIG. 24B are partially structural schematic views of the LED filament of the disclosure in an embodiment at different viewing angles;
• FIG. 25 is a schematic view of the slant arrangement of the LED chips of the disclosure in an embodiment;
• FIG. 26 is a structural schematic view of the connection between the LED chip and the electrode of the disclosure in an embodiment; and
• FIG. 27A to FIG. 27C are structural schematic views of the connection between the LED chip and its corresponding electrode through two conductive portions of the disclosure in an embodiment at different viewing angles.
• FIG. 28 is a schematic view of an LED bulb lamp adopting the LED filament illustrated in FIGS. 1 to 27A according to an embodiment of the disclosure.

The embodiments of the present invention are illustrated by the following specific examples, and those skilled in the art can readily understand other advantages and effects of the present invention from the disclosure of the present specification. In the following description, reference is made to the accompanying drawings, which illustrate several embodiments of the present disclosure. It should be understood that other embodiments may be utilized, and modifications in module or unit configuration, electrical connection and operation may be made without departing from the spirit and scope of the present disclosure. The following detailed description shall not be regarded as restrictive, and the scope of the embodiments of the present invention is limited only by the claims of the granted patent. The terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the present invention.

It shall be understood that although the terms first, second and the like may be used herein to describe various elements or parameters in some instances, such elements or parameters shall not be limited by these terms. These terms are merely used to distinguish one element or parameter from another. For example, a first electrical connection portion may be referred to as a second electrical connection portion, and similarly, a second electrical connection portion may be referred to as a first electrical connection portion, without departing from the scope of the various described embodiments. Both the first electrical connection portion and the second electrical connection portion describe an electrical connection portion, but they do not refer to the same electrical connection portion unless otherwise clearly specified by the context. The same applies to the first bonding portion and the second bonding portion, the first bent portion and the second bent portion, as well as the first bending point and the second bending point.

As used herein, the terms "or" and "and/or" shall be interpreted in an inclusive manner, meaning any one or any combination thereof. Accordingly, "A, B or C" or "A, B and/or C" means any of the following: A; B; C; A and B; A and C; B and C; and A, B and C. Exceptions to this definition shall only apply where combinations of elements, functions, steps or operations are inherently mutually exclusive in any manner.

It shall be understood that when an element such as a layer, region or substrate is referred to as being "on" or extending "onto" another element, the element may be directly on or directly extending onto the other element, or intermediate elements may be present there between. Conversely, when an element is referred to as being "directly on" or "directly extending onto" another element, no intermediate elements are present there between. It shall also be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or intermediate elements may be present there between. Conversely, when an element is referred to as being "directly connected" or "directly coupled" to another element, no intermediate elements are present there between.

Relative terms such as "below", "above", "upper", "lower", "horizontal" or "vertical" may be used herein to describe the relationship of one element, layer or region to another element, layer or region as illustrated in the drawings. It shall be understood that such terms are intended to encompass different orientations of the device other than those depicted in the drawings. In the present invention, the definitions of "vertical", "horizontal" and "parallel" include a tolerance of ±10% based on standard definitions. For example, vertical generally refers to an included angle of 90 degrees relative to a reference line; while in the present invention, "vertical" includes an angle ranging from 80 degrees to 100 degrees.

The terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the present invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It shall also be understood that the terms "comprise", "comprises", "include" and/or "includes" as used herein specify the presence of the stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or combinations thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein shall have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. It shall also be understood that the terms used herein shall be construed to have meanings consistent with their meanings in the context of the present specification and the relevant art, and shall not be construed in an idealized or overly formal sense unless expressly so defined herein.

Unless otherwise explicitly stated, comparative quantitative terms such as "above" and "below" are intended to include the concept of equality. By way of example, "above" means not only "greater than" in a mathematical sense, but also "equal to".

In some embodiments, the present disclosure discloses an LED filament. As a light-emitting element, the LED filament is provided with a certain bendability, so that it can be bent into a required shape and arranged in a lighting fixture. For example, the LED filament disclosed herein may be applied to an LED bulb lamp or other LED filament lamps.

Please refer to FIG. 1 and FIG. 2. FIG. 1 is a partially perspective schematic view of the LED filament of the disclosure in an embodiment and FIG. 2 is a cross-sectional schematic view along line A-A in FIG. 1. As shown in FIG. 1 and FIG. 2, the LED filament 10 includes at least one LED chip (at least two LED chips 101, 102 are shown in the figure as an example), at least one electrode (at least two electrodes 103, 104 are shown in the figure as an example), a light conversion layer 105 (in a specific embodiment, the light conversion layer can be called "plastic layer" or "silica gel layer") and a conductive portion 106. Adjacent LED chips 101, 102 are electrically connected by the conductive portion 106 to implement an electric connection between the LED chips 101, 102. The conductive portion 106 is electrically connected between the LED chip 101 or 102 and the electrode 103 or 104 to implement an electric connection between the LED chip 101 or 102 and the electrode 103 or 104. The light conversion layer 105 wraps the LED chips 101, 102, the conductive portion 106 and at least part of the electrodes 103, 104.

After the electrodes 103, 104 have been connected to a power source (a voltage source or a current source), the LED filament 10 can emit light. As shown in FIG. 1 and FIG. 2, a cross-section of the LED filament 10 is configured into, but not limited to, a rectangular shape, while a triangular, circular, oval, polygonal, or rhombic shape is also available, and the cross-section of the LED filament 10 may even be an irregular shape such as a square with chamfered or rounded corners.

In an embodiment, the light conversion layer 105 includes silica gel and fluorescent powders, and the light conversion layer 105 may further include heat dispersing particles. For example, the heat dispersing particles may be nanometer oxide particles such as, but not limited to, nanometer particles formed by aluminum oxide (Al₂O₃), silicon oxide (SiO₂), zirconia (ZrO₂), titanium oxide (TiO₂), calcium oxide (CaO), strontium oxide (SrO) or barium oxide (BaO).

In an embodiment, as shown in FIG. 1 and FIG. 2, the light conversion layer 105 includes a top layer 1051 and a carrying layer 1052 (in specific embodiments, the carrying layer can be called base layer). The top layer 1051 wraps the LED chips 101, 102, the conductive portion 106 and the electrodes 103, 104 with at least exposing part of the two electrodes 103, 104 (or exposing at least part of the two electrodes 103, 104). The carrying layer 1052 includes an upper surface and a lower surface opposite to the upper surface. In comparison with the lower surface of the carrying layer, the upper surface 1052 of the carrying layer 1052 is adjacent to the top layer 1051. In some examples, each of the top layer 1051 and the carrying layer 1052 may be a layered structure with at least one layer. Preferably, in some embodiments, the layered structure may be one of fluorescent powder glue with high plasticity (in comparison with fluorescent powder film), fluorescent powder film with low plasticity, and a transparent layer, or the layered structure may be a combination of at least any two thereof. The fluorescent powder glue or the fluorescent powder film includes the following components: silica gel-modified polyimide and/or glue. The fluorescent powder glue/film may also include fluorescent powder and inorganic oxide nanoparticles (or heat dispersing particles). The transparent layer can be made of light-transmitting resin (such as silica gel or polyimide) or a combination thereof. The glue can be, but is not limited to, silica gel. It should be understood that the above-mentioned structure and composition of the top layer 1051 and the carrying layer 1052 are only examples. In other examples, the top layer 1051 and the carrying layer 1052 may have the same or different structures and/or compositions to form a variety of LED filaments with different properties.

In an embodiment, in the height direction of the LED filament 10 (the Z-axis direction in FIG. 1 and FIG. 2), the height of the top layer 1051 is greater than the height of the carrying layer 1052. The top layer 1051 includes an upper surface and a lower surface opposite thereto. The upper surface of the carrying layer 1052 is in contact with at least part of the lower surface of the top layer 1051. The LED chip 101, 102 includes an upper surface and a lower surface opposite thereto. The upper surface of the LED chip 101, 102 is closer to the upper surface of the top layer 1051 than the lower surface of the LED chip 101, 102. The distance between the lower surface of the LED chip 101, 102 and the lower surface of the carrying layer 1052 is less than the distance between the lower surface of the LED chip 101, 102 and the upper surface of the top layer 1051, i.e., the path of the heat generated by the LED chips 101, 102 being conducted to the outer surface of the carrying layer 1052 is shorter, so that heat is hard to be accumulated, thereby allowing the LED filament to obtain a better heat-dissipation effect.

To increase the combination strength of the top layer 1051 and the carrying layer 1052, in some embodiments, the contact area, shapes or interfaces of the top layer 1051 and the carrying layer 1052 may be properly adjusted to make the junction surface between these two layers be not a single plane. In an example, at least part of the contact surfaces of the top layer 1051 and the carrying layer 1052 form surfaces which match with each other. Such matching may be engaging, for example, surfaces which engage with each other may be wavy or jagged. In another example, the upper surface of the carrying layer 1052 may also be configured with higher roughness to enhance the combination strength with the top layer 1051. In still another example, the carrying layer 1052 may be provided with multiple via holes to make the top layer 1051 penetrate the carrying layer 1052 to increase the contact area between the top layer 1051 and the carrying layer 1052. Furthermore, after the top layer 1051 penetrates the via holes, the top layer 1051 may further extend to the other side of the carrying layer 1052. Therefore, the top and the bottom of the carrying layer 1052 are held by the top layer 1051, so that the connection between the carrying layer 1052 and the top layer 1051 is similar to pivoting..

It is noted that the top layer 1051 as shown in FIG. 1 and FIG.2 disposed on the upper surface of the carrying layer 1052 is an exemplary structure of the light conversion layer 105 only. The top layer 1051 and the carrying layer 1052 may also be disposed to be other connecting manners. For example, the carrying layer 1052 may be provided with a receiving groove in the length direction of the LED filament (the Y-axis direction in FIG. 1 and FIG. 2), the LED chips 101, 102 are disposed on the bottom of the receiving groove, and the top layer 1051 is filled in the receiving groove. For another, the carrying layer 1052 is configured as six surfaces wrapping the LED chips 101, 102 (i.e., the LED chips 101, 102 are wrapped in the central portion of the carrying layer 1052), and the top layer 1051 wraps the carrying layer 1052. The disclosure does not limit the structure of the light conversion layer 105.

The LED chips 101, 102 are wrapped in the light conversion layer 105. The LED filament may include one, two, or more LED chips (i.e., three or more than three). The shape of the LED chip may be of, but not limited to, a strip shape. A strip-shaped chip may have less electrodes to reduce the opportunity of shading the light emitted from an LED. In addition, surfaces of the LED chips 101, 102 may be coated with a transparent conductive indium tin oxide (ITO). The ITO layer is helpful to even distribution of current and improvement of luminous efficiency of the LED chips 101, 102. In detail, the length-width ratio of the LED chip may be configured into 2:1 to 10:1, for example, but not limited to, 14×28 or 10×20. In addition, the LED chips 101, 102 may adopt LED chips with large power operated with a low current, so that the LED chips 101, 102 can still have sufficient intensity under the condition of keeping a low current density, and the LED chips 101, 102 will not generate a large amount of heat to further improve the overall luminous efficiency.

The LED chip 101, 102 itself may adopt a sapphire substrate or a light-permeable transparent substrate, such that the substrate of the LED chip 101, 102 will not shade the light emitted from the LED chip 101, 102. In other words, the LED chip 101, 102 itself can emit light from its periphery.

The LED chips are electrically connected with each other. As shown in FIG. 1 and FIG. 2, adjacent LED chips 101, 102 are electrically connected with each other through the conductive portion 106. Take FIG. 1 and FIG. 2 as an example, each LED chip 101, 102 may be electrically connected in series, but the electric connection is not limited thereto; the electrical connection may also be done in parallel first and then in series. For example, but not limited to, two LED chips 101, 102 are first connected in parallel, and then two parallel-connected chips 101, 102 are then connected in series. An embodiment in which two LED chips are first connected in series and then two series-connected chips are then connected in parallel is also available.

The electrodes 103, 104 are disposed to correspond to the LED chips 101, 102 and are correspondingly electrically connected to the LED chips 101, 102. As shown in FIG. 1 and FIG. 2, each LED chip 101, 102 is arranged in a row and adjacent LED chips 101, 102 adopt an electric connection in series. The two electrodes 103, 104 are disposed at two ends of the LED filament to be separately connected with two ends of the LED chips 101, 102. Each electrode 103, 104 is partially exposed from the light conversion layer 105. The arrangement of the electrodes 103, 104 and the LED chips 101, 102 is not limited thereto.

Please refer to FIG. 3 to FIG. 7, which are schematic views of arrangements of the LED chips and the electrodes in different embodiments.

In the embodiment shown in FIG. 3, adjacent LED chips 101, 102 still adopt an electric connection in series, but multiple LED chips 101, 102 are divided into two rows to be disposed on the LED filament 10 (i.e., adjacent LED chips 101, 102 are alternately arranged in the width direction of the filament 10 (the X-axis direction in FIG. 3), in other words, the LED chips 101, 102 located at different rows of the two rows of LED chips 101, 102 are incompletely superposed when viewed from a lateral side of the filament, or the superposing area is less than 100%), and the two rows of LED chips 101, 102 are respectively arranged along the length direction of the LED filament 10 (the Y-axis direction in FIG. 3). Adjacent LED chips 101, 102 are connected with each other through the conductive portion 106. In FIG. 3, the two electrodes 103, 104 are disposed at two ends of the LED filament 10 to be connected with two ends of the LED chips 101, 102 through the conductive portion 106. Each electrode 103, 104 is partially exposed from the light conversion layer 105. In the embodiment shown in FIG. 3, the LED chips 101, 102 has a length size wc along the length direction of the LED filament 10. The ratio of the sum of lengths wc of all LED chips 101, 102 (i.e., Σwc) to the length of the LED filament 10 is greater than 0.5, 0.6, 0.65 or 0.7 to guarantee the arrangement density of the LED chips 101, 102 in the length direction of the LED filament 10 so as to increase the total luminous flux and reduce the graininess of light emission. Because the adjacent LED chips 101, 102 are alternately arranged in the width direction of the LED filament 10, a better bendability can be obtained under the condition of the LED chips 101, 102 having the same intervals. Contrarily, in the case that the ratio of the sum of lengths wc of all LED chips 101, 102 (i.e., Σwc) to the length of the LED filament 10 is greater than 0.5, 0.6, 0.65 or 0.7 and the LED chips 101, 102 are arranged in a single row, the LED filament 10 may have poor bendability, so that the LED filament cannot be bent properly and the shape of the LED filament 10 will be limited.

In the embodiment shown in FIG. 4, the multiple LED chips 101, 102 are arranged into an inverted-U shape or an n-shape, and the adjacent LED chips 101, 102 adopt an electric connection in series. The electrodes 103, 104 are arranged at the open end of the inverted-U shape or the n-shape and respectively electrically connected to corresponding one of the LED chips 101, 102. From the perspective view, the two electrodes 103, 104 are disposed at an end of the LED filament 10 (the end corresponds to the open end of the inverted-U shape or the n-shape) and are partially exposed from the light conversion layer 105.

In some embodiments, as shown in FIG. 5 and FIG. 6, the multiple LED chips 101, 102 may also be arranged into at least two substantially parallel rows (two rows are shown in FIG. 5 and FIG. 6 as an example). Each row of LED chips 101, 102 is respectively electrically connected in series. The two electrodes 103, 104 are disposed at two ends of the at least two rows of LED chips 101, 102 and respectively connected to each row of LED chips 101, 102 to form an configuration in which two LED chips are first connected in series and then two series-connected chips are then connected in parallel. FIG. 5 and FIG. 6 adopt two electrodes as an example, but the disclosure is not limited thereto, three or four electrodes may be available, for example, one of the electrodes 103, 104 in FIG. 5 or FIG. 6 is replaced with two independent sub-electrodes, the two sub-electrodes are respective positive terminals of an electric power and the remained electrode is a common ground terminal, or all of two electrode in FIG. 5 or FIG. 6 are replaced with two sub-electrodes to match with different applications.

In the embodiment shown in FIG. 6, one of the rows of LED chips, which is the closest to an end of the LED filament, is referred to as LED chip a₁, and the LED chips in this row from an end of the LED filament to the other end are referred to as a₁, a₂, a₃, ..., and a_m (m is an integer). The other one of the rows of LED chips, which is the closest to an end of the LED filament, is referred to as LED chip b₁, and the LED chips in this row from an end of the LED filament to the other end are referred to as b₁, b₂, b₃, ..., and b_n (n is an integer). In the length direction of the LED filament 10 (the Y-axis direction in FIG. 6), LED chip b_n is between LED chip a_n and LED a_n+1 (for example, when viewing from the length direction, LED chip b₁ is between LED chip a₁ and LED chip a₂, and LED chip b₂ is between LED chip a₂ and LED chip a₃). Further, the projection of LED chip b_n in the width direction of the LED filament 10 and the projection of LED chip a_n in the width direction of the LED filament 10 (the X-axis direction in FIG. 6) do not have an overlapping area. In other words, in some embodiments, one row of LED chips and the other row of LED chips are alternately arranged in the width direction (the X-axis direction in FIG. 6). Of course, in some embodiments, the projection of LED chip b_n in the width direction of the LED filament 10 and the projection of LED chip a_n in the width direction of the LED filament 10 (the X-axis direction in FIG. 6) have a certain overlapping area, but the overlapping area is less than 100%. It should be understood that FIG. 6 adopts two rows of LED chips, which have the same numbers, to serve as an example. In actual applications, the numbers of two rows of LED chips are not necessarily the same or different, i.e., the maximum of n may be greater than, less than, or equal to the maximum of m, as long as one row of LED chips, which has a less number and a corresponding number of LED chips in the other row are alternately arranged or at least partially alternately arranged with each other. The remaining LED chips of the row having a greater number are still extending and arranged along the length direction of the LED filament.

In some embodiments, the projection of LED chip bn in the width direction of the LED filament and the projection of LED chip an in the length direction (Y-axis direction in FIG. 6) of the LED filament 10 do not overlap in any region.

In some embodiments, the projection of LED chip bn in the width direction of the LED filament and the projection of LED chip an in the length direction (Y-axis direction in FIG. 6) of the LED filament 10 overlap in at least a partial region.

Under the arrangement of the same number of LED chips, the longer the LED filament is, the larger the interval between two adjacent LED chips is. After the LED filament is lit, light spots (or called graininess) seen by the naked eye will become more obvious to seriously affect viewing comfort of users. In addition, the LED filaments with the same length, the greater the number of LED chips is, the smaller the interval between two LED chips is, and heat generated by adjacent LED chips will be affected mutually. To guarantee that the LED filament has a great effect of light emission and heat dissipation performance, the embodiment shown in FIG. 6 adopts two rows of LED chips connected in parallel, and the LED chips in one row and the LED chips in the other row are alternately arranged in the width direction of the LED filament, so that the light emitted by one row of LED chips can complement light spots generated by the other row of LED chips to improve the light-emitting effect of the LED filament. In addition, in comparison with an LED filament with the same LED filament length and the same number of LED ships, an interval between two adjacent LED chips in each row of LED chips is larger, so heat generated by adjacent LED chips will be hard to be affected mutually and the junction temperature of the LED filament lowers.

Moreover, as shown in FIG. 7, on the condition of the arrangement of the LED chips as shown in FIG. 6, the projections of LED chips in one row and LED chips in the other row have an overlapping area in the length direction of the LED filament 10 (the Y-axis direction in FIG. 7) so as to reduce the width of the LED filament to make both the width of the LED filament closer to a conventional tungsten filament lamp, thereby allowing the LED filament to be more pretty when being bent or wound. In detail, each of LED chip a_m and LED b_n has multiple sides.

In the length direction of the LED filament 10, a side of LED chip b_n is between the same sides of LED chip a_n and LED chip a_n+1 (for example, in FIG. 7, a side of LED chip b₁ is between a side a₁₁ of LED chip a₁ and a side a₂₁ of LED chip a₂). In some embodiments, the side a₁₁ faces the side a₂₁.

In some embodiments, in the width direction of the LED filament 10 (for example, the X-axis direction in FIG. 7), widths of LED chip a_m and LED chip b_n are wa and wb, respectively. The width w of the LED filament 10 is not less than the sum of wa and wb, i.e., w≥wa+wb.

In any embodiment shown in FIG. 1 to FIG. 7, adjacent LED chips 101, 102 are electrically connected with each other through the conductive portion 106, and the LED chips 101, 102 and the electrodes 103, 104 are electrically connected with each other through the conductive portion 106, too. The conductive portion 106 may be a conductive metal wire, conductive film, or conductive metallic sheet. In the following embodiments, the conductive portion 106 is configured into a conductive metal wire as an example, which should not be deemed as a limitation to the disclosure. A conductive metal wire serving as the conductive portion 106 as an example, the diameter of the conductive metal wire may be configured to be between 0.5mil and 1.5mil and may be a single metal wire such as a gold wire, a silver wire, an aluminum wire or a copper wire or an alloy wire made of two or more metals with a certain proportion such as a gold-silver alloy wire.

The connection between the conductive portion 106 and the LED chips 101, 102 and the connection between the conductive portion 106 and the electrodes 103, 104 are fixed connections. In detail, the LED chips 101, 102 is provided with a first electrical connecting portion and a second electrical connecting portion (for example, the electrical connecting portion may be a solder joint or pad). The first end of the conductive portion 106 is fixed on the second electrical connecting portion of an LED chip 101, and the second end is fixed on the first electrical connecting portion of another LED chip 102 adjacent to the LED chip 101, so as to implement an electrical connection or signal connection between adjacent LED chips 101, 102. The electrode 103, 104 is also provided with an electrical connecting portion (for example, the electrical connecting portion may be a solder joint or pad). The first end and the second end of the conductive portion 106 are respectively fixed to the electrode 103, 104 and the electrical connecting portion of the LED chip 101, 102 adjacent to the electrode 103, 104, so as to implement an electrical connection or signal connection between the electrodes 103, 104 and the LED chips 101, 102.

In some embodiments, the conductive portion 106 is formed by wiring. The wiring is formed by wire bonding. In some embodiments, a wire and a corresponding electrical connecting portion are connected and fixed with each other using thermocompression bonding, ultrasonic bonding or thermosonic bonding to form each conductive portion 106 in the LED filament 10. These bonding methods require applying pressure to the wire.

Specifically, the wire bonding may be implemented using a wire bonding machine (which may be referred to as a wire soldering machine). The wire bonding machine is provided with a ceramic capillary which has a through hole (also referred to as wire hole) allowing the wire to pass through. The wire is heated in front of the ceramic capillary using a firing member to form a ball-shaped article, and the ceramic capillary brings the ball-shaped article to move downward to correspond to the electrical connecting portion to be connected (for example, the second electrical connecting portion of an LED chip) to apply pressure on the wire to form the first joining portion (or also referred to as the first soldering point), so that the fixation of the first end of the conductive portion is implemented. Then, the ceramic capillary is moved toward another electrical connecting portion to be connected (for example, the first electrical connecting portion of another LED chip adjacent to the LED chip) along a constant trace, thereby forming the arc shape of the conductive portion. Further, the ceramic capillary again moves downward to correspond to the electrical connecting portion to apply pressure on the wire to form the second joining portion (or also referred to as the second soldering point), so that the fixation of the second end of the conductive portion is implemented. Thereafter, the ceramic capillary is moved laterally to cut the wire and a wire bonded conductive portion can be formed. In other words, during the wire bonding process, the wire is between the LED chip and the ceramic capillary or between the electrode and the ceramic capillary, and by using the ceramic capillary to apply pressure on the wire, the wire and the LED chip (or the electrode) can be bonded.

It is noted that the wire is referred to the material used for forming the conductive portion such as a conductive metal wire, and the conductive portion formed thereby is a conductive metal wire, too. In addition, the disclosure refers to the region formed by joining the wire and the electrical connecting portion as "joining portion". To distinguish different joining portions, during the process of forming a conductive portion, the region formed by joining the start point of the wire and the electrical connecting portion is referred to as first joining portion (or first soldering joint), the region formed by joining the end point of the wire and the electrical connecting portion is referred to as second joining portion (or second soldering joint), an end of the conductive portion, which is connected to the first joining portion, is defined as a first end of the conductive portion, and an end of the conductive portion, which is connected to the second joining portion, is defined as a second end of the conductive portion.

Referring to FIG. 8, a structural schematic view of the conductive portion, according to one embodiment of the present disclosure is shown. FIG. 8 shows the conductive portion 106 connected between adjacent LED chips 101 and 102 as an example. The conductive portion 106 may also be connected between the LED chip 101, 102 and the electrode 103, 104. After the conductive portion 106 has been formed, the connection quality of the conductive portion 106 primarily depends upon three positions B, C, and D in FIG. 8. That is, an unreliable connection in the conductive portion 106 mainly results from poor quality at the positions B, C, or D. Position B is the junction of the first end of the conductive portion 106 and the first joining portion 1061. Position D is the junction of the second end of the conductive portion 106 and the second joining portion 1062, and position C is the line segment of the conductive portion 106 (i.e., the region between position B and position D).

As known to the inventor, the conductive portion106 may be formed using bond stick on ball (BSOB) technique. Take FIG. 8 as an example, a solder ball is placed on the first electrical connecting portion of the LED chip 102 in advance, the first joining portion 1061 is formed when bonding, and then the second joining portion 1062 is formed. The second joining portion 1062 is formed by pressing the wire on the solder ball to be joined so as to form the second joining portion 1062 as shown in FIG. 9. The second joining portion 1062 has a meshy surface. The second joining portion 1062 and the meshy surface are formed by the ceramic capillary 20, as shown in FIG. 10A and FIG. 10B. The surface of the second joining portion 1062 forms an obviously highly staggered region, which can be specifically said to be a bulge structure and an indent structure, according to some embodiments. The first height difference G₁ between the highest point of the bulge structure and the lowest point of the indent structure is between 5um and 15um, i.e., 5≤G₁≤15um, in some embodiments. The height difference between the bulge structure and the indent structure in the position D may also be called G₁, and 5um≤G₁≤15um, in some embodiments. The ceramic capillary 20 includes a surface 201 and a wire hole 202 for being passed by the wire (which may be a conductive metal wire). The surface is a face being in contact with the wire. In some embodiments, the surface 201 shown in FIG. 10A and FIG. 10B is configured as a mesh structure. The mesh structure is configured as a recess structure with an array arrangement in some embodiments. Further, in some embodiments, the depth of the recess structure may be made larger to make the surface 201 have higher roughness. Therefore, deep indentations will be left on the surface of the wire during the wire bonding process. As shown in FIG. 9, a surface of the second joining portion 1062 has a bulge structure and an indent structure, which correspond to the surface 201 of the mesh structure of the ceramic capillary 20 shown in FIG. 10A. The depth of the indent structure is relatively larger, and the overall thickness of the area in which the indent structure is located is relatively smaller. The thinner part is more susceptible to fracture compared to other regions. This may lead to issues such as an open or short circuit when connecting with other circuits, causing the LED filament to malfunction. For instance, some or all of the LED chips may not light up or may have abnormal brightness. In one embodiment, the first electrical connecting portion of the LED chip 102 is configured as a negative electrode (or cathode) of the LED chip 102, the second electrical connecting portion of the LED chip 102 is configured as a positive electrode (or anode) of the LED chip 102. That is, the first joining portion 1061 is formed on the positive electrode of the LED chip 101, and the second joining portion 1062 is formed on the negative electrode of the LED chip 102.

To solve the problem of fracture of position D, in some embodiments, the surface of the second joining portion 1062 is provided with a corresponding structure by providing ceramic capillaries with different surface structures. FIG. 11A and FIG. 11B. FIG. 11A are structural schematic views of the ceramic capillary according to embodiments of the present invention. FIG. 11B is a cross-sectional structural schematic view corresponding thereto. In comparison with the ceramic capillary structure shown in FIG. 10A and FIG. 10B, the surface 201 of the ceramic capillary 20 in FIG. 11A and FIG. 11B also features a mesh structure. However, the mesh structure in FIG. 11A and FIG. 11B is configured as a bulge structure with an array arrangement, and the bulge structure includes tiny bulges. That is, the height difference between the bulge portion and the non-bulge portion in the bulge structure is smaller, at least smaller than the depth of the recess structure shown in FIG. 10A and FIG. 10B. Furthermore, each bulge in the structure has an edge that is smoothly arcuate in shape, according to some embodiments of the present invention. FIG. 12 is a structural schematic view of the second joining portion 1062 according to one embodiment of the present disclosure. Like the tiny bulge structure on the surface 201 of the ceramic capillary 20 in FIG. 11A, the surface of the second joining portion 1062 in FIG. 12 is a tiny indented surface. The height difference between the highest point of the bulge structure and the lowest point of the indent structure is called second height difference G₂. In some embodiments, G₂ ranges between 1um and 5um, i.e., 1um≤G₂≤5um. The height difference between the highest point of the bulge structure and the lowest point of the indent structure in position D may also be called second height difference G₂. In some embodiments, G₂ ranges between 1um and 5um, i.e., 1um≤G₂≤5um. Position D and the second joining portion 1062 do not contain any particularly thin parts, which helps prevent fracture.

FIG. 13 is a structural schematic view of the ceramic capillary, according to one embodiment of the present invention. In comparison with the ceramic capillary shown in FIG. 10A, the surface 201 of the ceramic capillary 20 in FIG. 13 is configured as a frosted structure. The surface of the frosted structure has a grainy texture. For example, the grainy structure may be formed by a tiny bulge structure and an indent structure, but the height difference between the bulge structure and the indent structure is too small to form a noticeable mesh-like appearance. The ceramic capillary 20 uses the surface 201 with the frosted structure to exert pressure on the wire, creating a corresponding structure on the surface of the second joining portion 1062. In FIG. 14, a structural schematic view of the second joining portion according to one embodiment is shown. In comparison with the frosted structure of the surface 201 of the ceramic capillary 20 in FIG. 13, the surface of the second joining portion 1062 has a frosted surface without any obviously thin regions. This effectively improve the problem of fracture in position D. In FIG. 14, the height difference between the highest point of the bulge structure and the lowest point of the indent structure at position D, formed by the second joining portion 1062 of the ceramic capillary 20 shown in FIG. 13, is referred to as G₃. According to some embodiments, G₃ ranges from 0 to 1um, i.e., 0≤ G₃≤1um.

FIG. 15A to FIG. 15D are schematic views of the ceramic capillary 20 with surfaces having two different roughness levels, according to embodiments of the present invention. When comparing the ceramic capillary structure shown in FIG. 10A to the ceramic capillary in FIG. 15A to FIG. 15D, the surface 201 in FIG. 15A to FIG. 15D is configured to include a first portion 2011 and a second portion 2012. The second portion 2012 surrounds the first portion 2011, and the first portion 2011 and the second portion 2012 together form the surface 201 of the ceramic capillary. The roughness of the first portion 2011 is different from the roughness of the second portion 2012. Specifically, in one embodiment, the first portion 2011 is configured as a recess-shaped mesh structure, while the second portion 2012 is configured as a frosted structure. There is an obvious difference in surface roughness between the two portions 2011, 2012. The surface roughness of the first portion 2011 is much greater than the surface roughness of the second portion 2012. In the embodiment shown in FIG. 15B, the first portion 2011 is configured as a bulge-shaped mesh structure and the second portion 2012 is configured as a frosted structure. An obvious difference in surface roughness exists between the two portions 2011, 2012. The surface roughness of the first portion 2011 is much greater than the surface roughness of the second portion 2012. In the embodiment shown in FIG. 15C, the first portion 2011 is configured as a frosted structure and the second portion 2012 is configured as a recess-shaped mesh structure. An obvious difference in surface roughness exists between the two portions 2011, 2012. The surface roughness of the first portion 2011 is much less than the surface roughness of the second portion 2012. In the embodiment shown in FIG. 15D, the first portion 2011 is configured as a frosted structure and the second portion 2012 is configured as a bulge-shaped mesh structure. An obvious difference in surface roughness exists between the two portions 2011, 2012. The surface roughness of the first portion 2011 is much less than the surface roughness of the second portion 2012.

In the embodiments of the ceramic capillary with two different surface roughness, such as the ceramic capillary shown in any embodiment of FIG. 15A to FIG. 15D, when the ceramic capillary applies pressure to the wire (a conductive metal wire or the conductive portion) during wiring, the corresponding surface of the wire will also exhibit two different surface roughness. FIG. 16 is a structural schematic view of the second joining portion according to one embodiment of present invention. Surface of the second joining portion 1062 in FIG. 16 has two different roughness which is formed by the ceramic capillary shown in FIG. 15D. According to the embodiment shown in FIG. 16, the problem of fracture at position D can be effectively improved.

In other embodiments, the surface of the ceramic capillary may also be configured to have regions with more than two different roughness levels. This allows the surface of the joined portion, formed by applying pressure, to have regions with more than two different roughness levels. This can also improve the problem of fracture at position D. In addition, the surface of the ceramic capillary with varying levels of roughness may also be arranged in non-annular patterns. In some embodiments, it may be in the form of independent blocks, strips, or other shapes, as long as there are surfaces with two or more noticeable surface roughness levels on the surface of the ceramic capillary to be apply pressure to the wire.

In some embodiments, the wire hole 202 in the ceramic capillary has at least two different diameters. In some embodiments, the wire hole 202 may include a circular through hole portion and a cylindrical through hole portion connected to a small surface of the circular through hole portion. The diameter of the larger surface of the circular through hole is greater than the diameter of the wire.

In the above embodiments, the problem of fracture of the conductive portion can be improved by changing the surface structure of the second joining portion.

In other embodiments of the present disclosure, the conductive portion 106 formed by the BWB (Ball Wire Bonding), as shown in FIG. 8. It is also necessary to place a solder ball on the first electrical connecting portion of the LED chip 102 in advance. During the bonding process, the first joining portion 1061 is formed first, followed by the formation of the second joining portion 1062. The second joining portion 1062 is formed by using a ceramic capillary method to press the wire to be bonded on the solder ball that has been placed on the first electrical connecting portion. Another solder ball is then soldered and pressed thereon to form the second joining portion 1062, creating a three-layer structure with the conductive portion 106 being sandwiched between two solders. (See FIG. 17A for a schematic view of the second joining portion, according to one embodiment of the present disclosure). FIG. 17B is a corresponding cross-sectional schematic view. As a result, the second end of the conductive portion is protected by the solder ball to effectively prevent the conductive portion from fracturing at position D. The process involves bonding a solder ball onto a corresponding position of the LED chip 102 and pressing the solder ball to form the required shape. Then, the conductive portion 106 is bonded on a side of the first solder ball that is away from the LED chip 102. Finally, a second solder ball is bonded on a side of the conductive portion 106 that is away from the first solder ball in order to fix the conductive portion 106 and the LED chip 102, and ultimately form the second joining portion 1062. The LED chip 102 is bonded with the melted solder first. In the electrical connection, the current is conducted from the conductive portion 106 to the solder (i.e., the first solder ball) bonded with the LED chip 102 first, and then conducted to the LED chip 102.

In some embodiments, when the first solder ball, the conductive portion 106 and the second solder ball are bonded to the LED chip 102, the projection area of the flattened first solder ball (or first solder layer) and the flattened second solder ball (or second solder layer) on the LED chip 102 after soldering are larger than the projection area of the bonding region between the first solder layer, the second solder layer, and the conductive portion 106 on the LED chip 102, such that the flattened first solder ball and the flattened second solder ball wrap the conductive portion 106 and the bonding region between the first solder layer and the conductive portion 106 as well as the bonding region between the second solder layer and the conductive portion 106. The first flattened solder ball and the second flattened solder ball are at least partially bonded, so the two flattened solder balls after soldering can completely wrap the bonding region of the conductive portion 106 to increase the strength of the bonding region of the conductive portion 106 to avoid fracture.

In some embodiments, the projection area of the bonding region between the conductive portion 106 and the solder balls on the LED chip is smaller than the projection area of the first flattened solder ball on the LED chip, and the projection area of the first flattened solder ball on the LED chip is smaller than the projection area of the second flattened solder ball on the LED chip. The second flattened solder ball completely covers the bonding region between the first flattened solder ball and the conductive portion 106 on the LED chip 102. The flattened second solder ball is at least partially directly bonded to the LED chip 102.

In other some embodiments of the disclosure, the conductive portion 106 is formed by the BBOS (Bond Ball on Stitch) technique. In FIG. 8, when bonding, the first joining portion 1061 is formed first. Then the ceramic capillary is moved to apply pressure and bond the wire to the first electrical connecting portion of the LED chip 102. Subsequently, another solder ball is formed on the wire, resulting in the formation of the second joining portion 1062, as shown in FIG. 18A and FIG.18B (FIG. 18A is a structural schematic view of the second joining portion 1062, according to an embodiment, and FIG. 18B is a cross-sectional schematic view corresponding to FIG. 18A). Thus, the second end of the conductive portion is still covered by a solder layer to greatly improve the problem of fracture of the conductive portion at position D and increase the efficiency of wire soldering. In one embodiment, the first electrical connecting portion of the LED chip 102 is configured as a positive electrode (also called anode), and the second electrical connecting portion of the LED chip 102 is configured as a negative electrode (also called cathode). That is, in one embodiment, the first joining portion 1061 is formed on the negative electrode of the LED chip 101, and the second joining portion 1062 is formed on the positive electrode of the LED chip 102. In one embodiment, the conductive portion 106 is bonded with the LED chip 102 first, and then a solder ball is bonded on a side of the conductive portion 106, which is away from the LED chip 102 to finally form the second joining portion 1062. The projection area of the solder on the LED chip 102 is larger than the projection area of the bonding region between the conductive portion 106 and the LED chip 102, so that the bonding region of the conductive portion 106 can be completely wrapped on the LED chip 102. That is, the conductive portion 106 itself is bonded to the LED chip 102, and the LED chip is further wrapped by a solder ball. Therefore, two fixations are provided to increase firmness and reduce the number of processing steps, according to one embodiment.

Further, in any of the embodiments using the ceramic capillary to apply pressure to the wire to perform bonding, if a portion of the loading surface of the ceramic capillary is above an edge of the LED chip 102, the position at which the wire is applied with a pressure will bear a stronger cutting force caused by the edge of the LED chip 102 and the wire is thus easy to be fractured. FIG. 19A and FIG. 19B are schematic views of the cutting phenomenon of the second end of the conductive portion above an edge of the LED chip 102. In FIG. 19A and FIG. 19B, the cutting phenomenon is marked by a circle M. When the bonding position is excessively adjacent to an edge of the LED chip, the lower portion of the wire at which the wire is applied with the pressure will correspond to or adjacent to the edge of the LED chip or the edge of the electrode, wherein the height of the edge may have a sudden change. Accordingly, the junction of the second end of the conductive portion 106 will be affected by cutting forces and raise fracture.

Accordingly, in any of the embodiments adopting the manner which using the ceramic capillary to apply pressure on the wire to implement wiring, the second joining portion may be further arranged on the LED chip (or the electrode) with a first preset distance to the edge of the LED chip (or the electrode). In the embodiment, the edge of the LED chip (or the electrode) is referred to the edge of the LED chip (or the electrode) corresponding to the intersectant side of the projection of the LED chip (or the electrode) and the conductive portion in the height direction of the LED filament. A first preset distance exists between the second joining portion and the LED chip (or the electrode). In other words, in wiring, the position of the wire, which is applied with a pressure, is provided with a flat loading surface which can eliminate the cutting effect to greatly reduce the risk of fracture of the wire. Take FIG. 18A and FIG. 18B as an example, a first preset distance wd exists between the second joining portion 1062 and the edge of the LED chip 102. The junction of the second joining portion 1062 formed on the positive electrode of the LED chip 102 and the conductive portion 106 gradually inclines or rises from the near end toward the distal end (i.e., extending form the positive electrode of the LED chip 102 toward the conductive portion 106) to form a joining slope or a joining ramp or form a joining portion which gradually becomes thicker and thicker from the near end toward the distal end, so as to eliminate the problem of sudden change of the height of the edge shown in FIG. 19A and FIG. 19B. The junction of the second joining portion 1062 of the positive electrode of the LED chip 102 and the conductive portion 106 forms a complete loading surface of the second joining portion 1062. In comparison with FIG. 19B, the second joining portion 1062 moves forward by a certain distance toward the inside of the LED chip, so that the lower side of the wire in FIG. 18A is a complete loading surface and no cutting occurs at position D to further reduce the risk of fracture of the wire.

In FIG. 18A and FIG. 18B, it should be understood that the distance between the edge of the second joining portion 1062 and the edge of the LED chip (or the electrode) stands for the first preset distance. For example, the first preset distance of the second joining portion may be configured within a range between 20um and 60um, preferably, in some embodiments, between 30um and 50um, such as 30um, 35um, 40um, 45um or 50um. Of course, in other embodiments, the first preset distance may also be the distance between the center point of the second joining portion 1062 and the edge of the LED chip (or the electrode) in which a length corresponding to the radius of the second joining portion is added under the circumstance shown in FIG. 18A and FIG. 18B. For example, the first preset distance of the second joining portion may be configured within a range between 20um+R1 and 60um+ R1, preferably, in some embodiments, a range between 30um+R1 and 50um+R1, such as 30um+R1, 35um+R1, 40um+R1, 45um+R1 or 50um+R1, where R1 stands for the radius of the second joining portion.

In some embodiments, the second joining portion is formed by using the ceramic capillary to continuously apply pressure on the wire after the ceramic capillary moves downward to the electrical connecting portion to be connected on the LED chip (or the electrode), therefore, in some embodiments, by arranging a second preset distance between the electrical connecting portion on the LED chip (or the electrode) and the edge of the LED chip (or the electrode), the second joining portion can also be arranged on the LED chip (or the electrode) with keeping the first preset distance between the edge of the LED chip (or the electrode) and the second joining portion. There is no necessary relationship between the first preset distance and the second preset distance. The first preset distance may be greater than, equal to, or less than the second preset distance. In some embodiments, a distance between the edge of the electrical connecting portion and the edge of the LED chip (or the electrode) may be used to stand for the second preset distance. For example, the second preset distance may be configured within a range between 20um and 60um, preferably, in some embodiments, between 30um and 50um, such as 30um, 35um, 40um, 45um or 50um. In other embodiments, a distance between the center of the electrical connecting portion and the edge of the LED chip (or the electrode) may be used to stand for the second preset distance. For example, the second preset distance may be configured within a range between 20um+R2 and 60um+R2, preferably, in some embodiments, between 30um+R2 and 50um+R2, such as 30um+R2, 35um+R2, 40um+R2, 45um+R2 or 50um+R2, where R2 stands for the radius of the electrical connecting portion, for example, the radius R2 of the electrical connecting portion may be configured within a range between 25um and 35um such as 25um, 30um or 35um.

FIG. 9to FIG. 19B and related descriptions thereto analyze and solve the problem of fracture of the conductive portion 106 at position D, but the fracture of the conductive portion 106 may occur at position B. Fracture at position B still causes malfunctions of the conductive portion 106 to further make the LED filament malfunction.

During the process of forming the first joining portion, malfunctions will occur during the electronic flame-off ball formation to result in serious damage at position B. As shown in FIG. 20, which is a structural schematic view of the first joining portion, in the region defined by a dotted line, the wire is seriously misaligned with the first joint portion. Fracture easily occurs in the misaligned region. Thus, in some embodiments of the disclosure, the conductive portion adopts a silver conductive metal wire. During the process of forming the first joining portion, the electronic flame-off ball formation is proper and no damage occurs at position B. As shown in FIG. 21, which is a structural schematic view of the first joining portion of the disclosure in an embodiment, the wire extends upward from the first joint portion without any misalignment.

Furthermore, as shown in FIG. 8, the conductive portion 106 extends between the first joining portion 1061 and the second joining portion 1062 and has a certain arc portion. Please refer to FIG. 22A and FIG. 22B, which are partially schematic views of the first end of the conductive portion of the related art at different viewing angles. The first joining portion 1061 is formed on the surface of the LED chip 101. The conductive portion 106 extends upward along the first joining portion 1061, and an included angle of approximately 90 degrees is between the conductive portion 106 and the surface at which the first joining portion 1061 is. That is, the conductive 106 extends from the first joining portion 1061 substantially along the height direction of the LED chip (the Z-axis direction in FIG. 22A and FIG. 22B). The conductive portion 106 further has a bent portion 1063 (or called bent point). The bent portion 1063 makes the conductive portion 106 extend from the height direction of the LED chip toward the length direction of the LED chip (the Y-axis direction in FIG. 22A and FIG. 22B).

In the arc portion of the conductive portion 106 shown in FIG. 8, FIG. 22A, and FIG. 22B, the start orientation of the bent portion 1063 is to correspond to the height direction of the LED chip (i.e., correspondingly toward the direction of the first joining portion 1061 or the Z-axis direction in FIG. 22A) and then is bent toward the length direction of the LED chip (the Y-axis direction in FIG. 22A). Such an arc structure makes the joint position (position B) of the conductive portion 106 and the first joining portion 1061 be a fulcrum of the bent portion 1063, and the force exerted to the bent portion 1063 will be eventually delivered to position B. Therefore, in the process of producing or using the LED filament, fracture at position B will occur to cause malfunctions of the LED filament when the LED filament is vibrated, bent, or fell down which makes the bent portion 1063 bear a force.

Therefore, in some embodiments of the disclosure, structural design is applied to the arc portion of the conductive portion to address the issue of the fracture of position B. In one embodiment, the conductive portion includes at least two bent portions to make the conductive portion be extending along at least two different planes (or along at least three different direction). In some embodiments, the conductive portion has a first bent portion and a second bent portion to make the conductive portion have a part perpendicular to the LED chip 101 (or along the height direction of the LED chip 101) and a part parallel to the LED chip 101.

Please refer to FIG. 23A and FIG. 23B, which are partially schematic views of the first end of the conductive portion of present invention in an embodiment. As shown, the conductive portion 106 extends upward from the first joining portion 1061 (it can be understood as an angle of approximately 90 degrees is between the conductive portion 106 and the surface at which the first joining portion 1061 is) and bent along the width direction of the LED chip 101 to form a first bent portion 1064, and the conductive portion 106 further extends and is bent along the length direction of the LED chip 101 to form a second bent portion 1065. In other words, in some embodiments, the conductive portion 106 has the first bent portion 1064 and the second bent portion 1065. The conductive portion 106 extends upward from the first joining portion 1061 and extends toward the width direction of the LED chip 101 through the first bent portion 1064 and toward the length direction of the LED chip 101 through the second bent portion 1065. The conductive portion extending upward from the first joining portion 1061 may also be understood as the conductive portion 106 extending from the first joining portion 1061 substantially along the height direction or perpendicular to the LED chip 101 (the Z-axis direction in FIG. 23A and FIG. 23B). The conductive portion 106 extending toward the width direction of the LED chip 101 may also be understood as substantially extending along the width direction of the LED chip 101.

In comparison with the structure shown in FIG. 22A and FIG. 22B, the conductive portion 106 shown in FIG. 23A and FIG. 23B, the region between the first bent portion 1064 and the second bent portion 1065 may serve as a buffering region for buffering or dispersing force exerted to the conductive portion 106 to avoid or reduce deformation of the conductive portion 106 to prevent fracture at position B. In detail, the first bent portion 1064 and the second bent portion 1065 shown in FIG. 23A and FIG. 23B may adjust the extension direction of the conductive portion 106 from a direction perpendicular to the chip into along the width direction of the chip and then further adjust the extension direction of the conductive portion 106 into along the length direction of the chip. Such configuration will affect neither the connection between the conductive portion 106 and adjacent two LED chips nor the connection between the LED chip and the electrode. However, such configuration makes the conductive portion 106 form an arc outswing, i.e., a correspondingly buffering region, and the force apply to the conductive portion 106 will be released in the buffering region (in other words, the force is shunted into different directions) without being transmitted to the first bent portion 1064 or with only a very small part being transmitted to the first bent portion 1064 and subsequent position B. Therefore, there is no main stress applied on the easy-to-fracture region of the conductive portion, so that the conductive portion 106 would not fracture easily.

Further, the height D1 of the first bent portion 1064 (i.e., the height between the first bent portion 1064 and the surface of the LED chip) is configured within a range between 80um and 120um. The length D2 of the buffering region (i.e., the length between the first bent portion 1064 and the second bent portion1065) is configured within a range between 100um and 120um.

FIG. 24A and FIG. 24B are structural schematic views of the LED filament according to an embodiment of present invention. The conductive portion 106 has a first portion 1066, a second portion 1067 connected to the first portion 1066, and a third portion 1068 connected to the second portion 1067. When the first portion 1066 is projected on a corresponding LED chip (or the electrode) along the height or thickness direction of the LED filament (the Z axis direction shown in FIG. 24A and FIG. 24B), the first portion 1066 is completely within the LED chip (or the electrode). In other words, the first portion 1066 does not exceed the edge of the corresponding LED chip (or the electrode) along the length direction of the LED filament (the Y axis direction shown in FIG. 24A and FIG. 24B). When the second portion 1067 is projected on corresponding two adjacent LED chips (or an LED chip and an electrode connected to the LED chip) connected through the conductive portion 106 along the length direction of the LED filament, the second portion 1067 is between the corresponding two adjacent LED chips (or the LED chip and the electrode). In other words, the second portion 1067 is between the corresponding two adjacent LED chips (or an LED chip and an electrode connected to the LED chip) along the length direction of the LED filament which indicates that the second portion 1067 is between the edges of the two adjacent LED chips (or the edges of the LED chip and the electrode). The third portion 1068 corresponds to the second end of the conductive portion 106, and the third portion 1068 is used to be connected to the LED chip 102 (or the electrode). It can also be understood that, when the third portion 1068 is projected on the corresponding LED chip (or the electrode) along the height or thickness direction of the LED filament, the third portion 1068 is completely within the LED chip (or the electrode). In other words, the third portion 1068 does not exceed the edge of the corresponding LED chip (or the electrode) in the length direction of the LED filament.

In some embodiments, the first portion 1066 corresponds to the first end of the conductive portion 106, one end of the first portion 1066 is connected to the LED chip 101 (or the electrode), and the other end of the first portion 1066 is connected to the second portion 1067, and the other end of the first portion 1066 does not exceed the corresponding LED chip 101 (or the electrode) in the length direction of the LED filament. Further, the first portion 1066 includes the first bent portion 1064 and the second bent portion 1065 as shown in FIG. 23A and FIG. 23B.

In some embodiments, the ratio of the length of the first portion 1066 to the distance between the junction of the first portion 1066 and the LED chip and the edge of the LED chip in the length direction of the LED chip (the projection length of the first portion 1066 in the height or thickness direction of the LED filament) is greater than 1.15, 1.2, 1.3 or 1.4 to reduce the risk of fracture of the junction of the first portion 1066 and the LED chip when the first portion 1066 is pulled.

In some embodiments, the ratio of the length of the first portion 1066 to the distance between the junction of the first portion 1066 and the LED chip and the edge of the first portion 1066 in the length direction of the LED chip (the projection length of the first portion 1066 in the height or thickness direction of the LED filament) is less than 2. If the first portion 1066 is too long, the first portion 1066 will have a larger bending extent or occupy a space in the height or thickness direction of the LED filament. This will adversely affect the LED filament (for example, a larger bending extent may cause a greater inner stress in the first portion 1066 to occupy a space in the height or thickness of the LED filament;, a thicker light conversion layer would be required to cover the LED filament).

In some embodiments, the ratio of the length of the first portion 1066 to the projection length of the first portion 1066 in the height or thickness direction of the LED filament is greater than the ratio of the length of the second portion 1067 to the projection length of the second portion 1067 in the height or thickness direction of the LED filament. It is expressed by a formula: L1/T1>L2/T2, where L1 is the length of the first portion 1066, T1 is the projection length of the first portion 1066 in the height or thickness direction of the LED filament, L2 is the length of the second portion 1067, and T2 is the projection length of the second portion 1067 in the height or thickness direction of the LED filament. Usually, when the LED filament is bent, the junction of the first portion 1066 and the LED chip (or the electrode) is easier to be fractured because of being pulled. As a result, the risk of fracture of the junction of the first portion 1066 and the LED chip (or the electrode) can be further reduced by configuring L1/T1>L2/T2.

The length of the third portion 1068 adopts the length of the first portion 1066 in any embodiment, which can be referred to the descriptions about the first portion 1066, and the description of the third portion 1068 is omitted.

When the LED filament is bent, the second portion 1067 of the conductive portion 106 is a main bending region (parts at which the LED chips are located are not easy to be bent). To reduce the risk of fracture of the second portion 1067 when the LED filament is bent, the length of the second portion 1067 is configured to be greater than the distance between two adjacent LED chips (or an LED chip and an electrode) corresponding thereto. That is, the length of the second portion 1067 is configured to be greater than the projection length of the second portion 1067 in the height or thickness direction of the LED filament, so as to provide a greater margin to the conductive portion 106 when the LED filament is bent to avoid fracture.

In some embodiments, the ratio of the length of the second portion 1067 to the distance between corresponding two adjacent LED chips (or an LED chip and an electrode) (or the projection length of the second portion 1067 in the height or thickness direction of the LED filament) is greater than 1.1, 1.2, 1.3, or 1.4. Therefore, when the LED filament is bent, the second portion 1067 has a sufficient length to be bent and deformed, thereby preventing the second portion 1067 from fracturing.

In some embodiments, the ratio of the length of the second portion 1067 to the distance between corresponding two adjacent LED chips (or an LED chip and an electrode) (or the projection length of the second portion 1067 in the height or thickness direction of the LED filament) is less than 2. If the length of the second portion 1067 is configured to be too long, it is disadvantageous to the covering performance of the light conversion layer, or even the conductive portion 106 may be exposed from the light conversion layer. In addition, the excessively long second portion 1067 may also cause material waste.

In some embodiments, the second portion 1067 has at least two bending points to make the conductive portion 106 appear substantially wavy (w-shaped or m-shaped). As shown in FIG. 24A, the second portion 1067 has a first bending point 1067a and a second bending point 1067b. The surface on which the junction between the LED chip and the conductive portion is located serves as a base plane. The first bending point 1067a is below the first joining portion 1061 or the second joining portion 1062, and the second bending point 1067b is above the first joining portion 1061 or the second joining portion 1062. Therefore, after the second portion 1067 is connected to the first portion 1066, the second portion 1067 extends to the first bending point 1067a on a descendent trend, then taking the first bending point 1067a as a turning point, the second portion 1067 extends to the second bending point 1067b on a rising trend, and finally taking the second bending point 1067b as another turning point, the second portion 1067 extends on a descendent trend to be connected to the third portion 1068 to make the conductive portion 106 appear wavy (an inverted-w-shaped or m-shaped). Accordingly, such configuration further makes the conductive portion 106 have greater stretchability and thus the conductive portion 106 is not easy to fracture.

In some embodiments, please refer to FIG. 25, which is a schematic view of the slant arrangement of the LED chips 101 of the invention in an embodiment, as shown, two adjacent LED chips 101 are arranged aslant. The slant arrangement indicates that the two adjacent LED chips 101 are arranged slant relative to the length direction of the LED filament with long sides of two adjacent LED chips 101 being kept parallel. That is, the two LED chips 101 are aslant arranged with the same slant angle so as to reduce the arc span of the conductive portion connected between the adjacent LED chips by 1/3, and the stretchability of the conductive portion becomes larger to reduce the risk of fracture of the conductive portion between the LED chips. Further, the slant angle of the LED chip may be configured within a range between 10° and 20°, where the slant angle is an included angle between the long side of the LED chip and the length direction of the filament as angle α in FIG. 25.

The conductive portion used to be connected between the LED chip and the electrode is easy to fracture at position C. For example, in an embodiment of being provided with multiple rows of LED chips and two rows of LED chips which are close to the electrode having different distances, as shown in FIG. 6 and FIG. 7, two rows of LED chips are alternately arranged, and the distance between the LED chip b_n and the electrode 104 is obviously less than the distance between the LED chip a_m and the electrode 104. The arc span of the conductive portion 106 directly connected between the LED chip a_m and the electrode 104 is obviously greater than the arc span of the conductive portion 106 directly connected between the LED chip b_n and the electrode 104. Therefore, in comparison with the conductive portion 106 between the LED chip b_n and the electrode 104, the stretchability of the arc of the conductive portion 106 between the LED chip a_m and the electrode 104 is small, and thus the conduction portion is easy to fracture.

Therefore, in some embodiments, at least the LED chips which are near the electrode and to be connected to the electrode are configured to have a common solder joint so as to decrease the length of the conductive portion and thus reduce the risk of fracture of the conductive portion between the LED chip and the electrode. Please refer to FIG. 26, which is a structural schematic view of the connection between the LED chip and the electrode of the invention in an embodiment. The LED chip a_m is a chip in the first row of chips, which is the closest to the electrode 104, and the LED chip b_n is a chip in the second row of chips, which is the closest to the electrode 104. Two ends of a conductive portion 106 are respectively connected to the first electrical connecting portion of the LED chip a_m and the first electrical connecting portion of the LED chip b_n to make the LED chip a_m and the LED chip b_n have a common-electrode (which may be a common-cathode or a common-anode, the common-electrode is common-cathode when the first electrical connecting portion is configured as an cathode, and the common-electrode is common-anode when the first electrical connecting portion is configured as an anode). That is, the first electrical connecting portion of the LED chip b_n serves as a common-electrode connecting point and another conductive portion 106 is used to be connected between the common-electrode connecting point and the electrode 104. Under this configuration, the arc span required by the conductive portion 106 connected with the LED chip a_m greatly decreases (by almost one second) to reduce the risk of fracture of the conductive portion between the chip and the electrode.

In addition, other solutions may be adopted to improve the problem of fracture of the conductive portion between the LED chip and the electrode. In some embodiments, the LED chip and the electrode corresponding thereto are connected with each other through at least two conductive portions. Each conductive portion has at least two bending points to form at least two bending regions. The bending regions of the at least two conductive portions are alternately arranged in the height or thickness direction of the LED filament. In some embodiments, the at least two conductive portions may be configured as the structure of the conductive portion mentioned in any above embodiment. Please refer to FIG. 22A and FIG. 24B and related descriptions thereto, as long as the connecting position of the at least two conductive portions is correspondingly adjusted.

Please refer to FIG. 27A to FIG. 27C, which are structural schematic views of the connection between the LED chip and the corresponding electrode through two conductive portions of the invention in an embodiment at different viewing angles. For the sake of description, two conductive portions are respectively referred to a first conductive portion 106' and a second conductive portion 106". The first end of the first conductive portion 106' is connected to the LED chip 101, and the second end is connected to the electrode 104. The first end of the second conductive portion 106" is connected to the electrode 104, and the second end is connected to the LED chip 101. The first conductive portion 106' has a first bending point 1067a' and a second bending point 1067b'. The first bending point 1067a' correspondingly forms a first bending region with an upward opening (it may also be understood that the first conductive portion 106' extends toward the first bending point 1067a' on a descendent trend first, and then taking the first bending point 1067a' as a turning point, the first conductive portion 106' extends on a rising trend to form the first bending region). The second bending point 1067b' correspondingly forms a second bending region with a downward opening (it may also be understood that the first conductive portion 106' extends on a rising trend first, and then taking the second bending point 1067b' as a turning point, the first conductive portion 106' extends on a descendent trend to form the second bending area). The second conductive portion 106" has a first bending point 1067a" and a second bending point 1067b". The first bending point 1067a" correspondingly forms a first bending region with an upward opening (it may also be understood that the second conductive portion 106" extends toward the first bending point 1067a'' on a descendent trend first, and then taking the first bending point 1067a'' as a turning point, the second conductive portion 106'' extends on a rising trend to form the first bending region). The second bending point 1067b" correspondingly forms a second bending region with a downward opening (it may also be understood that the second conductive portion 106" extends on a rising trend first, and then taking the second bending point 1067b'' as a turning point, the second conductive portion 106'' extends on a descendent trend to form the second bending area). Because the first conductive portion 106' and the second conductive portion 106" are connected between the LED chip 101 and the electrode 104 on contrary descendent and rising trends, after connection, the first bending region formed by the first bending point 1067a' of the first conductive portion 106' and the second bending region formed by the second bending point 1067b" of the second conductive portion 106" are correspondingly alternately arranged along the height direction of the LED chips. Likewise, the second bending region formed by the second bending point 1067b' of the first conductive portion 106' and the first bending region formed by the first bending point 1067a" of the second conductive portion 106" are correspondingly alternately arranged along the height direction of the LED chips. It should be understood that this the alternately arrangement along the height direction of the LED chips does not necessarily require that two bending regions must absolutely align with each other in the height or thickness direction of the LED filament as long as the overall bending trends of the two bending region are alternately arranged.

The forming positions and manners of the bending points of the first conductive portion 106' and the second conductive portion 106" may be referred to the descriptions of FIG. 24A and FIG. 24B, and related descriptions are omitted. The connection and arc structure of the first end of the first conductive portion 106' and the LED chip 101 may adopt the structure described in any embodiment shown in FIG. 22A to FIG. 23B. The connection and arc structure of the first end of the second conductive portion 106" and the electrode 104 may adopt the structure described in any embodiment shown in FIG. 22A to FIG. 23B with no more repeat. Further, the first conductive portion 106' and the second conductive portion 106" may have more bending points. For example, as shown in FIG. 27B, the second conductive portion 106" further has a third bending point 1067c", and the second conductive portion 106" is continuously connected to the LED chip 101 through the third bending point 1067c".

In any embodiment disposed with at least two conductive portions connected between the LED chip and the electrode corresponding thereto, the bending areas of the at least two conductive portions are alternately arranged in the height or thickness direction of the LED filament so as to form complementarity to implement force dispersion and jointly bearing to avoid fracture of the conductive portion between the electrode and he LED chip.

As shown in FIG. 27C, the distance between one of the at least two conductive portions, which is close to the edge of the LED filament (the first conductive portion 106' in FIG. 27B) and the edge of the electrode is configured to be greater than or equal to 30um, preferably, in some embodiments, greater than or equal to 50um.

As shown in FIG. 27A, from the length direction of the LED filament, the height difference h₁ (i.e., the first turning point distance along the height direction) between the first bending point 1067a' of the first conductive portion 106' and the joining portion of the corresponding chip (the joining portion of the LED chip 101 shown in FIG. 27A) is configured within 40um±5%. The height difference h₂ (i.e., the second turning point distance along the height direction) between the second bending point 1067b' of the first conductive portion 106' and the joining portion of the corresponding chip (the joining portion of the LED chip 101 shown in FIG. 27A) is configured within 75um±5%. From the height or thickness of the LED filament, the first bending point 1067a' of the first conductive portion 106' is below the surface of the chip (the surface of the chip is a surface which is connected to the first conductive portion 106') ranging between 30um and 100um in height direction (the height of the first turning point in FIG. 27A). The second bending point 1067b' of the first conductive portion 106' is above the surface of the chip (the surface of the chip is a surface which is connected to the first conductive portion 106') ranging between 100um and 160um in height direction (the height of the second turning point in FIG. 27A).

As shown in FIG. 27B, from the length direction of the LED filament, the horizontal distance S1 (i.e., the first turning point distance along the length direction) between the first bending point 1067a" of the second conductive portion 106" and the joining portion of the corresponding electrode 104 is configured within 40um±5%. The horizontal distance S2 (i.e., the second turning point distance along the length direction) between the second bending point 1067b" of the second conductive portion 106" and the joining portion of the corresponding electrode 104 is configured within 75um±5%. The horizontal distance S3 (i.e., the third turning point distance along the length direction) between the third bending point 1067c" of the second conductive portion 106" and the joining portion of the corresponding electrode 104 is configured within 90um±5%. From the height or thickness of the LED filament, the first bending point 1067a" of the second conductive portion 106" (the LED chip 101 in FIG. 27B) is below the surface of the chip (the surface of the chip connected to the second conductive portion 106") ranging between 30um and 100um in height direction (the height of the first turning point in FIG. 27B). The second bending point 1067b" of the second conductive portion 106" (the LED chip 101 in FIG. 27B) is above the surface of the chip (the surface of the chip connected to the second conductive portion 106") ranging between 80um and 120um (the height of the second turning point in FIG. 27B).

It should be understood that, for an LED filament, an electrode needs to be connected with multiple LED chips through the conductive portion and different LED chips need to be connected with different electrodes. The invention does not necessarily require that the connection between the LED chip and the corresponding electrode must adopt the same structure, any person having ordinary skill in the art may adopt combinations of the above manners. For example, as shown in FIG. 27A and FIG. 27B, near the electrode 104, the connection with the LED 101 which is away from the electrode 104 adopts a two-wire manner, and the connection with the LED 101 which is adjacent to the electrode 104 still adopts a one-wire manner. Of course, the disposition shown in FIG. 27A and FIG. 27B, which uses at least two conductive portions, can also be used to connect two adjacent LED chips. The disclosure does not make any limitation for this.

The invention further provides a connecting method between two chips and a connecting method between a chip and an electrode. A structure corresponding to the LED filament provided by anyone of the embodiments of the disclosure can be formed by the methods. Please refer to the aforementioned descriptions of FIGS. 1-27C with no more repeat.

The invention further provides an LED filament lamp, which is disposed with the LED filament provided by anyone of the embodiments of the disclosure. Please refer to the aforementioned descriptions of FIG. 1 to FIG. 27C about the LED filament with no more repeat. In detail, the LED filament may be bent or deformed to be disposed in the LED filament lamp. For example, the LED filament lamp is a bulb lamp.

The invention further provides an LED bulb, which includes a lamp housing, a bulb base connected with the lamp housing. The lamp housing is disposed with at least one supporting arm, a stem and an LED filament. The stem includes a stand. Each supporting arm includes a first end and a second end opposite to each other. The first end of the supporting arm is connected to the stand. The second end of the supporting arm is connected to the LED filament. The LED filament may be configured into the LED filament provided by anyone of the embodiments of the disclosure. Please refer to FIG. 1 to FIG. 27C with no more repeat. The LED bulb may also be other structures, for example, the LED bulb includes a lamp housing, a bulb base connected with the lamp housing. The lamp housing is disposed with a stem and an LED filament.

Reference is made to FIG. 28, which is a schematic diagram of an LED bulb using the LED filament described in FIGS. 1 to 27A according to an embodiment of the present invention. The LED bulb 1 comprises a lamp cap 4 and a lamp envelope 5 connected to the lamp cap 4. The lamp envelope 5 and the lamp cap 4 form a sealed cavity, in which at least one cantilever 31, a stem 3, and at least one LED filament 10 are disposed. The stem 3 is connected to the lamp cap 4 and extends a post 30 away from the lamp cap 4. The stem 3 is further provided with at least one cantilever 31. Each cantilever 31 comprises a first end and a second end opposite to each other. The first end of the cantilever is connected to the post 30 (or the stem 3), and the second end of the cantilever 31 is connected to the LED filament 10. In some other embodiments, the cantilever may also be referred to as a conductive support. Electrodes 103 and 104 are respectively disposed at ends of the LED filament 10, one electrode is connected to the cantilever 31, and the other electrode is connected to the post 30 (or the stem 3). The LED filament 10 comprises a light conversion layer 105, at least one LED chip (101, 102), at least one electrode (103, 104), and a conductive portion 106. The light conversion layer 105 comprises a top layer 1051 and a carrier layer 1052. The top layer 1051 comprises an upper surface and a lower surface opposite to each other, the carrier layer 1052 comprises an upper surface and a lower surface opposite to each other, and the chip (101, 102) comprises an upper surface and a lower surface opposite to each other. At least part of the upper surface of the carrier layer 1052 is in contact with the lower surface of the top layer 1051. The upper surface of the LED chip (101, 102) is closer to the upper surface of the top layer 1051 than the lower surface of the LED chip is. The distance from the lower surface of the LED chip (101, 102) to the lower surface of the carrier layer is smaller than the distance from the lower surface of the LED chip to the upper surface of the top layer. Adjacent LED chips are connected and conducted through the conductive portion. The light conversion layer encapsulates at least partial regions of the LED chip (101, 102), the conductive portion 106, and the electrode. The conductive portion comprises at least two bent portions, and extends in at least two different planes.

In the LED filament 10 disposed inside the LED bulb, the internal LED chips (101, 102) are staggered along the width direction of the LED filament 10, and the ratio of the total length of the LED chips (101, 102) along the length direction of the LED filament to the length of the LED filament is greater than or equal to 0.5. The LED chips are connected in series, in parallel, in series - parallel connection, parallel - series connection, or a combination of any two thereof. The conductive portion 106 in the LED filament 10 comprises a first bent portion and a second bent portion, wherein the first bent portion extends along the length direction of the LED chip, and the second bent portion extends along the width direction of the LED chip. A buffer region is formed between the first bent portion and the second bent portion, which is an arc structure or other multi- fold structure domain, and the length of the buffer region ranges from 100 µm to 120 µm.

The conductive portion 106 comprised in the LED filament 10 inside the LED bulb further comprises a first portion, a second portion connected to the first portion, and a third portion connected to the second portion. When the first portion is projected onto the corresponding LED chip (or the electrode) along the thickness direction of the LED filament, it completely falls within the range defined by the LED chip (or the electrode). When the second portion is projected onto two adjacent LED chips (or the connected LED chip and the electrode) connected by the conductive portion along the length direction of the LED filament, it is located between the two adjacent LED chips (or the LED chip and the electrode). The third portion corresponds to the second end of the conductive portion, for connecting the LED chip (or the electrode), and when projected onto the corresponding LED chip (or electrode) along the thickness direction of the LED filament, it completely falls within the range defined by the LED chip (or the electrode).

A first electrical connection portion and a second electrical connection portion are disposed on the LED chip (101, 102) comprised in the LED filament 10 inside the LED bulb. The conductive portion 106 forms a first joining portion on the first electrical connection portion, and forms a second joining portion on the first joining portion via a solder ball. The second joining portion is at a preset distance from an edge of the LED chip, and in some embodiments, the surface of the second joining portion has at least two roughness levels.

In some embodiments, the LED filament 10 inside the LED bulb is such that the LED chip (101, 102) and the electrode (103, 104) are connected by at least two conductive portions 106.

In some embodiments, the conductive portion 106 of the LED filament 10 inside the LED bulb comprises a first conductive portion and a second conductive portion, both having a first bending point and a second bending point. The first bending point of the first conductive portion correspondingly forms a first bent region opening upward, and the second bending point forms a second bent region opening downward. The first bending point of the second conductive portion correspondingly forms a first bent region opening downward, and the second bending point forms a second bent region opening upward. That is, the first conductive portion and the second conductive portion are connected between the LED chip and the electrode in opposite rising and falling trends.

In some embodiments, one three- dimensional LED filament 10 is disposed inside the LED bulb 1.

In some embodiments, at least two intertwined LED filaments 10 are disposed inside the LED bulb 1.

With further reference to FIG. 28 and the foregoing description, the LED bulb 1 has a lamp envelope 5 with a central axis, i.e., the envelope 5 is symmetrically designed about the central axis. In some embodiments, the central axis is also the central axis of the lamp cap 4, which is connected to the envelope 5. A stem 3 located inside the lamp envelope 5 is further disposed along the central axis of the lamp envelope 5.

At least one cantilever 31 is further disposed inside the lamp envelope 5, and the cantilever 31 may also be referred to as a conductive support 31. In one embodiment, two conductive supports 31 are included, having opposite polarities.

A driving circuit is disposed inside the lamp cap 4 and electrically connected to the two conductive supports 31. A flexible LED filament is disposed inside the lamp envelope and electrically connected to the two conductive supports, the flexible LED filament comprising:

An LED segment comprising a plurality of LED chips (101, 102) connected in series and the light conversion layer 105 encapsulating the plurality of LED chips;

A first conductive electrode 103 at one of two ends of the LED segment, electrically connected to the plurality of LED chips (101, 102) and one of the two conductive supports 31, wherein a part of the first conductive electrode 103 is encapsulated by the light conversion layer 105;

As shown in FIGS. 1- 3, a second conductive electrode 104 is disposed at the other end of the two ends of the LED segment, i.e., a second conductive electrode 104 fixed and electrically connected to the plurality of LED chips and the other one of the two conductive supports 31, wherein a part of the second conductive electrode 104 is encapsulated by the light conversion layer 105. Conductive portions 106 are disposed between the plurality of LED chips, connecting and conducting adjacent LED chips or an LED chip and an electrode, i.e., conductive portions 106 electrically connected between the plurality of LED chips.

Each of the plurality of LED chips is provided with an electrical connection portion, and one end of the conductive portion is connected to the electrical connection portion. As shown in FIGS. 23A and 23B, the conductive portion 106 has a first bent portion 1064 and a second bent portion 1065. The conductive portion extends from the electrical connection portion along a first direction of the LED chip (101, 102), bends via the first bent portion 1064 to extend along a second direction of the LED chip, and bends via the second bent portion 1065 to extend along a third direction of the LED chip, wherein the first direction, the second direction and the third direction are different directions. The first direction is the height direction of the LED chip, the second direction is the width direction of the LED chip, and the third direction is the length direction of the LED chip. The distance between the first bent portion 1064 and the surface of the LED chip ranges from 80 µm to 120 µm, and the distance between the first bent portion 1064 and the second bent portion 1065 ranges from 100 µm to 120 µm.

As shown in FIGS. 18A and 18B, the LED filament further comprises a first solder layer made of a solder material (such as solder paste, solder ball, etc.), and an end of the conductive portion 106 is located between the electrical connection portion of the LED chip 102 and the first solder layer. The projected area of the first solder layer 1062 on the electrical connection portion of the LED chip 102 is larger than the projected area of the bonding region between the conductive portion 106 and the electrical connection portion of the LED chip 102.

As shown in FIG. 18B, the end (or terminal) of the conductive portion 106, the electrical connection portion on the LED chip 102, and the first solder layer together form a joining portion 1062. The joining portion 1062 has a mesh surface, and a plurality of protrusions and a plurality of indentations are alternately arranged on the mesh surface.

As shown in FIGS. 17A and 17B, the LED filament further comprises a second solder layer made of a solder material (such as solder paste, solder ball, etc.), and the end of the conductive portion 106 is located between the first solder layer and the second solder layer.

Each of the projected area of the first solder layer on the electrical connection portion of the LED chip 102 and the projected area of the second solder layer on the electrical connection portion of the LED chip 102 is larger than the projected area of the bonding region between the conductive portion and the first solder layer and the second solder layer on the electrical connection portion of the LED chip 102.

The projected area of the bonding region between the conductive portion 106 and the electrical connection portion of the LED chip 102 is smaller than the projected area of the first solder layer, and the projected area of the first solder layer is smaller than the projected area of the second solder layer.

As shown in FIG. 7, the plurality of LED chips (101, 102) further comprises a first row of LED chips and a second row of LED chips, which are connected in parallel. The LED chips in the first row are connected in series, the LED chips in the second row are connected in series, and the first row of LED chips and the second row of LED chips are alternately arranged along the width direction of the LED filament.

As shown in FIGS. 27A, 27B and 27C, the LED filament further comprises a first conductive portion 106' and a second conductive portion 106'' electrically connected between the LED chip 101 and the first conductive electrode 104. One end of the first conductive portion 106' is connected to the LED chip 101, and the other end of the first conductive portion 106' is connected to the first conductive electrode 104. One end of the second conductive portion 106'' is connected to the first conductive electrode 104, and the other end of the second conductive portion 106'' is connected to the LED chip 101. The first conductive portion 106' first extends downward and then upward with a first bending point 1067a' of the first conductive portion as a first turning point, and then extends upward and then downward with a second bending point 1067b' of the first conductive portion as a second turning point. The second conductive portion 106'' first extends upward and then downward with a first bending point 1067b'' of the second conductive portion as a first turning point, and then extends downward and then upward with a second bending point 1067a'' of the second conductive portion as a second turning point.

It should be noted that the above-described features of the present invention can be arranged and combined in any way to improve LED lights, and the above embodiments are described only by way of example. The present invention is not limited thereto, and many modifications are possible without departing from the spirit of the invention and the scope defined by the appended claims.

The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.