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(11) | EP 0 491 163 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Method and apparatus for producing electrolytic copper foil |
| (57) Method and apparatus of producing an electrolytic copper foil which comprises passing
a stream of electrolyte between a rotating cathode (1) drum and at least one anode
(3) facing the drum, effecting electrodeposition of copper on the surface of the cathode
drum to form a copper foil, and thereafter peeling the foil from the drum, characterized
in that the anode is at least partly divided into a plurality of sub-anodes for controlling
foil thickness and that the foil thickness is uniformized or locally changed or modified
as desired by controlling the individual foil thickness-controlling sub-anodes. The present invention is conducted on the basis of (A) control in the direction of the width, (B) control in the direction of the length, (C) control in the directions of the width and the length and (D) pattern control. The control is effected by controlling either the quantities of electricity supplied to the individual foil thickness-controlling sub-anodes or the individual set positions of the sub-anodes. |
Field of the Invention
[0001] This invention relates to a method and apparatus of producing an electrolytic copper foil. More particularly, this invention relates to a method and apparatus of producing an electrolytic copper foil characterized by the provision of a plurality of foil thickness-controlling sub-anodes for uniformizing or otherwise locally changing or modifying as desired the thickness of the electrolytic copper foil being made and by the individual control of either the quantities of electricity being supplied to the individual foil thickness-controlling sub-anodes or the set positions of the sub-anodes. Under this invention, a high-quality electrolytic copper foil with a uniform thickness or an adjusted thickness in the direction of the width or the length or in the directions of both of them is obtained.
Background of the Invention
[0002] Electrolytic copper foil is produced by passing a stream of electrolyte between an anode of insoluble metal and a metallic cathode drum mirror-polished on the surface and supplying a potential between the anode and the cathode drum, thereby causing electrodeposition of copper on the cathode drum surface, and, when the electrodeposit has attained a predetermined thickness, peeling the same from the cathode drum. The copper foil thus obtained, called as untreated foil, is thereafter variously surface-treated to be final products.
[0003] In the apparatus for manufacturing electrolytic copper foil, the anode after operation for a given time period is worn, above all, to be of no use because it produces an ununiformity in the spacing between itself and the cathode drum. Especially it causes variation in thickness in the direction of the width or the length or both of the foil according to the characteristics peculiar to the apparatus used. FIG. 1 illustrates the relative position of a cathode drum and an anode as divided here into two anode sheets conventionally used for the manufacture of copper foil. In an electrolytic cell (not shown) containing an electrolyte, the cathode drum 1 is installed to be rotatable (clockwise in this case) as partly submerged in the electrolyte. The anode, e.g., two anode sheets 3, is disposed to cover generally the submerged lower half of the cathode drum 1 in spaced relation with a given clearance from the drum surface. Inside the electrolytic cell, the electrolyte is supplied at 6 o'clock position (of the hour hand, the same applying hereinafter) between the two anode sheets 3. It flows upward along the space between the cathode drum and the anode and overflows the upper edges of the anode for circulation. A rectifier 5 maintains a given current between the cathode drum and the anode.
[0004] As the cathode drum 1 rotates, the electrodeposit of copper from the electrolyte becomes thicker, and becomes a desired thickness around 9 o'clock position and an untreated foil that has attained a desired thickness is peeled off by suitable peeler means and wound up.
[0005] In the apparatus for manufacturing electrolytic copper foil, when operation has continued for a given time period, among others, the anode is locally worn with use. Consequently,the space between the cathode drum and the anode sheets varies and the resulting untreated foil becomes uneven particularly in thickness in the direction of the width between side portions and a central portion.
[0006] There are produced also variation in thickness along its length due to the lack of uniformity of the factors such as the distance between the anode and the cathode, flow velocity of the electrolyte being supplied, and the quantity of electricity supplied.
[0007] Thus, the untreated copper foil so produced varied in its thickness widthwise, lengthwise or in both of them as shown in FIG. 1.
[0008] With electrolytic copper foil, one of the important qualitative requirements is that it is uniform in thickness.
[0009] To uniformize the thickness of electrolytic copper foil widthwise, the following steps have hitherto been taken:
(1) Anode milling : - With an apparatus for the production of electrolytic copper foil, it has been common that anode after runs for a certain length of time is worn out of use because it makes the space between itself and the cathode drum uneven. As used herein, the expression "out of use" means an abnormal rise of the electrolytic voltage or serious unevenness in thickness of the copper foil produced. In order to avoid this, the anode after service for a given time period is cylindrically reformed on the surface by a special cutting tool.
(2) Partial anode cutting : - After anode milling, variation of thickness in the direction of the width of the resulting copper foil is determined. According to the data thus obtained, the anode surface is partially cut off to correct the thickness of the copper foil properly.
[0010] On the other hand, as to the variation in thickness of the length of an electrolytic copper foil produced, little consideration has hitherto been paid.
[0011] As stated above, in a conventional countermeasure, the production line must be stopped for correcting the surface of an anode for the purpose of uniformizing the thickness of a copper foil produced and even when the above steps are taken, they could not adequately prevent the variations in thickness of the copper foil produced.
[0012] Needless to say, it is in fact impossible to locally control the thickness of the copper foil as desired.
[0013] Copper foil is mostly used in printed-circuit boards. The modern tendency with those boards is toward higher density, with finer circuit patterns and thinner layers for higher degrees of multilayer integration. This has not only induced the development of thinner copper foils but has brought increasingly exacting requirements for the uniformity of foil thickness.
[0014] Accompanied with this, uniformizing the thickness in the direction of the length that has been overlooked has become a major problem to be solved, needless to mention the uniformity of the thickness in the direction of the width.
[0015] The two methods of the prior art described above for uniformizing the thickness in the direction of the width are disadvantageous in that neither permits the correction during the course of operation. They cannot cope with the variations in thickness of the foil in the direction of the width due to uncertain factors originating from causes other than anode, e.g., the thickness variations attributable to the cathode drum or to changes or lack of uniformity of the flow of the electrolyte. Among other shortcomings is the fact that the partial cutting of the anode is time-consuming and cumbersome and renders it not always easy to achieve the end.
[0016] There is also a need for locally changing or modifying as desired the thickness of a copper foil being produced, but it is in fact impossible to satisfy such need with the production technique presently conducted as already stated.
Object of the Invention
[0017] The object of the present invention is to develop a novel method and apparatus of producing electrolytic copper foil which permits the control in thickness of a copper foil including the uniformity and local change of thickness in the directions of width, length or both of the foil during operation and also the correction of thickness variation owing to indefinite and uncertain factors.
Summary of the Invention
[0018] The present inventors have conceived of composing an anode at least part of which is divided into a plurality of sub-anodes for controlling foil thickness wherein the sub-anodes are individually controlled so as to produce an electrolytic copper foil having a uniform thickness or an adjusted thickness. To this end it has been found desirable to control either the quantities of electricity being supplied to the individual sub-anodes or the set positions of the sub-anodes individually.
[0019] On the basis of these findings, this invention provides method of producing an electrolytic copper foil which comprises passing a stream of electrolyte between a rotating cathode drum and at least one anode facing the drum, effecting electrodeposition of copper on the surface of the cathode drum to form a copper foil, and thereafter peeling the foil from the drum, characterized in that the anode is at least partly divided into a plurality of sub-anodes for controlling foil thickness and that the foil thickness is controlled by controlling the individual sub-anodes. This invention also provides an apparatus therefor.
(A) Control in the direction of the width:
[0021]
A-1) A method of producing an electrolytic copper foil which comprises passing a stream of electrolyte between a rotating cathode drum and at least one anode facing the drum, effecting electrodeposition of copper on the surface of the cathode drum to form a copper foil, and thereafter peeling the foil from the drum, characterized in that the anode is at least partly divided widthwise into a plurality of sub-anodes for controlling foil thickness widthwise and that the foil thickness is controlled by controlling either the quantities of electricity being supplied to the individual sub-anodes or the individual set positions of the sub-anodes,
A-2) An apparatus for producing an electrolytic copper foil which comprises a rotatable cathode drum and at least one anode facing the cathode drum, so that an electrolyte is passed between the cathode drum and the anode to effect electrodeposition of copper on the surface of the cathode drum and thereafter the resulting copper foil is peeled from the drum, characterized in
(i) that at least the one anode is divided over the entire length widthwise into a plurality of sub-anodes for controlling foil thickness in the direction of the width and that means are provided to control individually the quantities of electricity supplied to the sub-anodes,
(ii) that the anode is partly divided widthwise into a plurality of sub-anodes for controlling foil thickness in the direction of the width and that means are provided to control individually the quantities of electricity supplied to the sub-anodes,
(iii) that at least one anode is divided widthwise into a plurality of sub-anodes, narrow in the middle portion and broad in the both edge portions of the anode, for controlling foil thickness in the direction of the width, and that means are provided to control individually the quantities of electricity supplied to the sub-anodes,
(iv) that at least one anode is divided widthwise into a plurality of sub-anodes, narrow in the both edge portions and broad in the middle portion of the anode, for controlling foil thickness in the direction of the width, and that means are provided to control individually the quantities of electricity supplied to the sub-anodes, or
(v) that at least a part of the anode is divided widthwise into a plurality of sub-anodes for controlling foil thickness in the direction of the width and that means are provided to control individually the set positions of the sub-anodes, and
A-3) A method of producing an electrolytic copper foil corresponding to said A-2) (i) to (v).
(B) Control in the direction of the length:
[0022]
B-1) A method of producing an electrolytic copper foil which comprises passing a stream of electrolyte between a rotating cathode drum and at least one anode facing the cathode drum, effecting electrodeposition of copper on the surface of the cathode drum, and thereafter peeling the resulting copper foil from the drum, characterized in that at least a part of the anode is divided lengthwise into a plurality of sub-anodes for controlling foil thickness and that the foil thickness in the direction of the length is controlled by controlling the quantities of electricity being supplied to the individual sub-anodes,
B-2) A method according to the above characterized in that the quantities of electricity being supplied to the individual sub-anodes are controlled individually on the basis of the thickness pattern in the direction of the length of the copper foil per revolution of the cathode drum,
B-3) An apparatus for producing an electrolytic copper foil wherein a stream of electrolyte is passed between a rotatable cathode drum and at least one anode facing the cathode drum to effect electrodeposition of copper on the surface of the cathode drum and thereafter the resulting copper foil is peeled from the drum, characterized in that at least a part of the anode is divided lengthwise into a plurality of sub-anodes for controlling foil thickness and that means are provided to control individually the quantities of electricity supplied to the individual sub-anodes to control the the thickness of the copper foil in the direction of the length, and
B-4) An apparatus according to the above characterized in that the quantities of electricity supplied to the individual sub-anodes are controlled individually on the basis of the thickness pattern in the direction of the length of the copper foil per revolution of the cathode drum.
(C) Control in the directions of the width and length:
[0023]
C-1) A method of producing an electrolytic copper foil which comprises passing a stream of electrolyte between a rotating cathode drum and at least one anode facing the cathode drum, effecting electrodeposition of copper on the surface of the cathode drum, and thereafter peeling the resulting copper foil from the drum, characterized in that at least a part of the anode is divided into a plurality of sub-anodes for controlling foil thickness lengthwise and a plurality of sub-anodes for controlling foil thickness widthwise and that the foil thickness is controlled lengthwise and widthwise by controlling the quantities of electricity being supplied to the individual sub-anodes in the direction of the length and the sub-anodes in the direction of the width, respectively,
C-2) A method according to the above characterized in that the quantities of electricity being supplied to the individual sub-anodes for controlling the foil thickness lengthwise and widthwise are controlled individually on the basis of a thickness pattern in the direction of the length and a thickness pattern in the direction of the width of the copper foil per revolution of the cathode drum, respectively,
C-3) An apparatus for producing an electrolytic copper foil wherein a stream of electrolyte is passed between a rotatable cathode drum and at least one anode facing the cathode drum to effect electrodeposition of copper on the surface of the cathode drum and thereafter the resulting copper foil is peeled from the drum, characterized in that at least a part of the anode is divided into a plurality of sub-anodes for controlling foil thickness lengthwise and a plurality of sub-anodes for controlling foil thickness widthwise and that means are provided to control individually the quantities of electricity supplied to the individual sub-anodes in the direction of the length and in the direction of the width to control the thickness of the copper foil lengthwise and widthwise, respectively,
C-4) An apparatus according to the above characterized in that the quantities of electricity supplied to the individual sub-anodes in the directions of the length and the width are controlled individually on the basis of the thickness pattern in the direction of length and the thickness pattern in the direction of width of the copper foil per revolution of the cathode drum, and
C-5) An apparatus according to the above wherein said sub-anodes for controlling the foil thickness widthwise correspond to the aforementioned A-2) (i) to (v).
(D) Pattern control:
[0024]
D-1) A method of producing an electrolytic copper foil which comprises passing a stream of electrolyte between a rotating cathode drum and at least one anode facing the cathode drum, effecting electrodeposition of copper on the surface of the cathode drum, and thereafter peeling the resulting copper foil from the drum, characterized in that at least a part of the anode is divided into a plurality of sub-anodes for controlling foil thickness and that the foil thickness is controlled lengthwise and widthwise by controlling the quantities of electricity being supplied to the individual sub-anodes for controlling foil thickness on the basis of the combined pattern combining a thickness pattern in the direction of the length and a thickness pattern in the direction of the width,
D-2) A method according to the above characterized in that the quantities of electricity being supplied to the individual sub-anodes are controlled individually on the basis of the combined pattern combining a thickness pattern in the direction of the length and a thickness pattern in the direction of the width of the copper foil per revolution of the cathode drum,
D-3) An apparatus for producing an electrolytic copper foil wherein a stream of electrolyte is passed between a rotatable cathode drum and at least one anode facing the cathode drum to effect electrodeposition of copper on the surface of the cathode drum and thereafter the resulting copper foil is peeled from the drum, characterized in that at least a part of the anode is divided into a plurality of sub-anodes for controlling foil thickness and that means are provided to control individually the quantities of electricity supplied to the individual sub-anodes to control the thickness of the copper foil lengthwise and widthwise on the basis of the combined pattern combining a thickness pattern in the direction of the length and a thickness pattern in the direction of the width, and
D-4) An apparatus according to the above characterized in that the quantities of electricity supplied to the individual sub-anodes are controlled individually on the basis of the combined pattern combining a thickness pattern in the direction of the length and a thickness pattern in the direction of the width of the copper foil per revolution of the cathode drum.
[0025] For locally changing or modifying the thickness of a copper foil as desired, the sub-anodes corresponding to the zone which needs such change or modification are controlled in the electricity supplied thereto or the set position in the manner as explained above.
Brief Description of the Drawings
[0026]
FIG. 1 is a diagrammatic perspective view of a main portion of a conventional apparatus for producing electrolytic copper foil.
FIG. 2 is a diagrammatic perspective view of an embodiment of the invention having two anode sheets one of which, on the copper foil-recovering side, is partly divided to provide sub-anodes for controlling the foil thickness widthwise;
FIG. 3 is a perspective view of the anode sheets of FIG. 2;
FIG. 4 illustrates another embodiment in which not only the anode sheet on the copper foil-recovering side but also the sheet on the electrodeposition-starting side is partly divided into sub-anodes for controlling the foil thickness widthwise;
FIG. 5 shows another embodiment having two anode sheets one of which, on the copper foil-recovering side, is divided over the entire length;
FIG. 6 shows still another embodiment in which only the middle portion of one anode sheet, on the copper foil-recovering side, is divided into sub-anodes;
FIG. 7 shows yet another embodiment in which only the both edge portions of one anode sheet, on the copper foil-recovering side, are divided into sub-anodes;
FIGs. 8a and 8b show a further embodiment in which the set positions of the sub-anodes for controlling the foil thickness are individually controlled and an embodiment of a position controlling mechanism, respectively.
FIG. 9 is a diagrammatic perspective view of an embodiment of the invention having two anode sheets one of which, on the copper foil-recovering side, is partly divided to provide sub-anodes for controlling the foil thickness lengthwise;
FIG. 10 is a perspective view of the anode sheets of FIG. 9.
FIG. 11 is a perspective view of an embodiment of the invention wherein the anode sheet on the copper foil recovering side is divided throughout into sub-anodes for controlling the foil thickness lengthwise in a plurality of rows.
FIG. 12 illustrates another embodiment in which the anode sheet on the electrodeposition-starting side also is partly divided into sub-anodes for controlling the foil thickness lengthwise.
FIG. 13 is a diagrammatic perspective view of an embodiment of the invention having two anode sheets one of which, on the copper foil-recovering side, is partly divided to provide sub-anodes for controlling foil thickness lengthwise and widthwise.
FIG. 14 is a perspective view of the anode sheets of FIG. 13.
FIG. 15 is a perspective view of the anode sheets of FIG. 14, of which the remainder of the anode sheet on the copper foil-recovering side is all divided into sub-anodes for controlling the foil thickness lengthwise in a plurality of rows.
FIG. 16 illustrates another embodiment in which the anode sheet on the electrodeposition-starting side too is partly divided into sub-anodes for controlling the foil thickness lengthwise.
FIG. 17 shows another embodiment in which in addition to sub-anodes for controlling the foil thickness lengthwise at the outer end, only the middle portion of one anode sheet, on the copper foil-recovering side, is divided into sub-anodes for controlling the foil thickness widthwise.
FIG. 18 shows still another embodiment in which in addition to sub-anodes for controlling the foil thickness lengthwise at the outer end, only the both edge portions of an anode sheet are divided into sub-anodes for controlling the foil thickness widthwise.
FIG. 19 is a diagrammatic perspective view of an embodiment of the invention having two sheets of anode one of which, on the copper foil-recovering side, is partly divided into sub-anode for pattern control.
FIG. 20 is a perspective view of the anode sheets of FIG. 19.
FIG. 21 is a perspective view of the anode sheets of FIG. 20, of which the anode sheet on the copper foil-recovering side is all divided into sub-anodes in a plurality of rows for pattern control.
FIG. 22 illustrates another embodiment in which the anode sheet on the electrodeposition-starting side too is partly divided into sub-anodes for pattern control.
Description of embodiments
[0027] With respect to several embodiments of this invention, explanation will be made with the reference to the drawings wherein common elements are designated by same reference numerals.
(A) Control in the direction of the width:
[0028] In accordance with the invention, at least a part of one, preferably at least one on the copper foil-recovering side, of the anode sheets already described with reference to FIG. 1 is divided widthwise into a plurality of sub-anodes for controlling foil thickness widthwise. It is, of course, possible to provide such sub-anodes as auxiliary anodes in addition to an existing anode.
[0029] Referring to FIGs. 2 and 3, there is illustrated an embodiment of the invention with a construction such that one of anode sheets, on the copper foil-recovering side, is partly divided into sub-anodes for controlling foil thickness.
[0030] FIG. 4 shows another embodiment constructed so that not only the anode sheet on the copper foil-recovering side but also the sheet on the electrodeposition-starting side is partly provided with sub-anodes for controlling foil thickness. Control is exercised both at the points where electrodeposition is started and concluded.
[0031] FIG. 5 depicts an embodiment in which one of two anode sheets, on the copper foil-recovering side, is split throughout the entire length into segmental sub-anodes for controlling foil thickness.
[0032] The larger the number of sub-anodes the more appropriately the control can be exercised. Greater difficulties will be involved, however, in fabrication and maintenance. Generally, depending on the width of the copper foil to be made and on the conditions of the foil-production equipment used, one anode is divided into from 10 to 40 sub-anodes.
[0033] Some apparatus for producing electrolytic copper foil show the tendency of producing a foil especially thin in the central zone or conversely along at least one edge portion. To cope with this, it may be found expedient to split only the central zone or along at least one edge portion, as the case may be, of at least one, or a part of one, of the anode sheets, on the copper foil-recovering side, in the direction of the width, into a plurality of sub-anodes for controlling foil thickness.
[0034] FIG. 6 illustrates yet another embodiment in which only the middle portion of one anode sheet, on the copper foil-recovering side, is divided into sub-anodes for controlling foil thickness and FIG. 7 is an embodiment in which the both edge portions of one anode sheet are divided into sub-anodes for controlling foil thickness. Needless to say, in FIGs. 6 and 7, the sub-anodes may form a part of the anode and, specifically in FIG. 7, either edge portion alone may be so divided. The choice depends on the conditions of the particular copper foil production equipment used.
[0035] Now the operation for the manufacture of electrolytic copper foil will be explained in conjunction with the embodiment shown in FIGs. 2 and 3.
[0036] In an electrolytic cell (now shown) which contains an electrolyte such as a sulfuric acid solution of copper sulfate, a cathode drum 1 which is a rotatable cylinder, e.g., of stainless steel or titanium, is held in place by support means, as partly submerged in the electrolyte and made rotatable clockwise in the embodiment shown. There are provided a plurality of, say two, arcuate insoluble anode sheets 3, covering approximately the submerged, lower half part of the cathode drum 1 and spaced a predetermined distance from the drum surface. The anode 3 preferably consists of two anode sheets disposed along at least lower quarter, each, of the cathode drum 1 as shown. According to the necessity, it may be replaced by a single anode sheet or by three, four, or more sheets.
[0037] In the embodiment being described, a part of the anode sheet on the copper foil-recovering side is comprised of sub-anodes 4 for controlling foil thickness widthwise, as described above. A suitable number of sub-anodes, 4', 4'', 4''', and so forth, are thus provided.
[0038] The space between the cathode drum and the anodes is kept constant, usually in the range from 2 to 100 mm. The narrower the space the less the electricity consumption but the more difficult will be the control of the film thickness and quality.
[0039] This space between the cathode drum and the anode sheets constitutes a flow passage for the electrolyte. The electrolyte is supplied at 6 o'clock position between two anode sheets 3 by way of a proper pump in the cell (not shown). It passes as divided streams in both directions along the space and overflows the both upper edges of the anode sheets for circulation.
[0041] As the cathode drum 1 rotates, electrodeposition of copper from the electrolyte starts, approximately at 3 o'clock position, and the deposit thickness increases until it attains a desired thickness at about 9 o'clock position where the electrodeposition comes to an end. The foil of the desired thickness is peeled off by suitable peeler means at about 12 o'clock position and wound up. The anode, especially of the lead type, is locally worn with use. This results in variation in space between the cathode drum and the anode. In addition, the cathode drum can be responsible for some variation in foil thickness, and the electrolyte stream can undergo a certain deflection or irregularity in flow. Altogether, they tend to cause localized variation in thickness in the direction of the width of the foil.
[0042] An explanation is made taking the case where variation in the direction of the width is caused under the above condition of production as an example.
[0043] With the embodiment being described, the thickness in the direction of the width of the untreated foil is determined after the peeling and, when a thickness variation beyond a permissible limit has been detected, electrical currents supplied to the specific sub-anodes 4 corresponding to the specific sections in the direction of the width are controlled independently of one another. To permit this individual control of the sub-anodes 4, sub-rectifiers 7 are connected between the individual sub-anodes 4 and the cathode drum 1.
[0044] The thickness values at different points in the direction of the width of the copper foil can be simply determined by suitable sampling, in terms of the weight per unit area. Alternatively, a thickness measuring instrument, such as of the static capacity detection type, may be installed in the winding route to monitor the thickness, cooperatively with the sub-rectifiers via feedback means.
[0045] Between adjacent sub-anodes is preferably interposed an insulating seal. Useful insulating materials for this purpose include sheets of PVC and cold curable rubber (for example, one marketed under the trade designation "RTV"). Insulation is provided instead by bonding adjacent sub-anodes with an insulating adhesive or integrally joining the sub-anodes with an insulating film therebetween.
[0046] According to this invention, the individual sub-anodes for controlling foil thickness widthwise can also be controlled through the control of their set positions. To attain the end, means are provided to support the individual sub-anodes 4 and move them toward or away from the cathode drum, independently of supports for the anode sheets 3 submerged in the electrolyte. FIG. 8a shows support rods 8', 8'', 8''' and so forth secured, respectively, to the sub-anodes 4', 4'', 4''' and so forth of FIG. 3. These support rods in an array 8 are individually moved back and forth by suitable position adjusting means such as screw or piston-cylinder units.
[0047] A typical example is illustrated in FIG. 8b. A screw block 10 is attached to each sub-anode 4, and a threaded rod 12 is in thread engagement with the block 10. The threaded rod 12 is linked through two universal joints 14 and 16 to a connecting rod 18, which in turn is rotated by a suitable motor. The two universal joints permit the block 10 to be held at a suitable point. With the rotation of the threaded rod 12 by the motor, the block 10 can be moved back or forth as desired. It should, of course, be obvious to one skilled in the art that the block 10 may be linked instead with a cylinder-piston assembly for reciprocating motion.
[0048] Thus, when the foil thickness in the direction of the the width being monitored after the peeling has varied beyond a permissible limit, the support rods 8 of the sub-anodes 4 facing the particular varied-thickness portion or portions in the direction of the width of the foil are displaced by the position control means. The closer each sub-anode moves toward the cathode drum, the higher the current density of the electrical power supplied and the thicker the electrodeposit of copper will become. Conversely, the farther the sub-anode is moved away from the drum, the lower the current density and the thinner the electrodeposit.
[0049] Under this embodiment, as described above, an electrolytic copper foil being manufactured can be controlled in thickness including uniformity and local change as desired in thickness by the use of sub-anodes for controlling foil thickness widthwise, through the control of either the electric supplies to or the set positions of the individual sub-anodes.
[0050] General technical matters explained in the above (A) in detail are applicable to (B) - (D) mentioned below. Accordingly, in (B) - (D) mentioned below, explanations overlapping (A) will be omitted.
(B) Control in the direction of the length:
[0051] Referring to FIGs. 9 and 10, there is illustrated an embodiment of the invention with a construction such that one of anode sheets, on the copper foil-recovering side, is partly divided into sub-anodes for controlling foil thickness lengthwise (hereinafter simply called "sub-anodes") 9. As an alternative, the sub-anodes may be replaced by a single sub-anode not divided in the width direction. It is possible to provide such sub-anode(s) as auxiliary anode(s) in addition to an existing anode.
[0052] FIG. 11 shows another embodiment in which sub-anodes 9 are provided in a plurality of rows throughout the anode sheet 5 on the copper foil-recovering side. Each row of sub-anodes may be replaced by a single sub-anode not divided widthwise.
[0053] FIG. 12 shows another embodiment constructed so that not only the anode sheet on the copper foil-recovering side but also the anode sheet on the electrodeposition-starting side is partly provided with sub-anodes for controlling foil thickness lengthwise.
[0054] The larger the number of the division in the direction of the width and the number of rows of the sub-anodes the more precisely the control can be exercised. Greater difficulties will be involved, however, in fabrication and maintenance. Generally,depending on the width of the copper foil to be made and on the conditions of the foil production equipment used, one anode is divided into from 10 to 40 sub-anodes per row.
[0055] Similarly in the (A), an explanation is made taking the case where the variation in the direction of the length is caused as an example. The operational manner of electrolytic copper foil production is similar to that explained in (A). As the cathode drum 1 rotates, electrodeposition of copper from the electrolyte starts, approximately at 3 o'clock position, and the deposit thickness increases until it attains a desired thickness at about 9 o'clock position where the electrodeposition comes to an end. The foil of the desired thickness is peeled off by suitable peeler means at about 12 o'clock position and wound up.
[0056] However, as stated above, localized variation in thickness in the direction of the length of the untreated foil results from factors such as the lack of uniformity of the flow velocity of the electrolyte being fed or of the supply of electricity.
[0057] In this embodiment the thickness pattern per revolution of the cathode drum of a sample of the actually formed copper foil is measured at some points in the directions of the length and width. In response to the measured results, a plurality of sub-rectifiers 7 adjust the current supplied between the individual sub-anodes 9 and the cathode drum 1.
[0058] For the purposes of the invention the expression "the thickness pattern per revolution of the cathode drum" is used to mean the variation in thickness of the copper foil formed upon one complete turn of the cathode drum measured, e.g., at 720 points chosen by dividing the copper foil area by 36 lengthwise and by 20 widthwise, and then calculating as 36× 20 = 720.
[0059] The individual sub-anodes can also be controlled herein through the control of their set positions as already explained. To attain the end, means are provided to support the individual sub-anodes 4 and move them toward or away from the cathode drum, independently of supports for the anode sheets submerged in the electrolyte. These sub-anodes are individually moved back and forth by suitable position adjusting means such as screw or piston-cylinder units. Support rods of the sub-anodes facing the particular varied thickness portion or portions in the direction of the length of the foil are displaced by the position control means. The closer each sub-anode moves toward the cathode drum, the higher the current density of the electrical power supplied and the thicker the electrodeposit of copper will become. Conversely, the farther the sub-anode is moved away from the drum, the lower the current density and the thinner the electrodeposit.
[0060] Thus, an electrolytic copper foil being manufactured can be controlled in thickness lengthwise by the use of sub-anodes for controlling foil thickness lengthwise, through the individual control of either the quantities of electricity being supplied to the sub-anodes or the set positions of the individual sub-anodes. The copper foil may be uniformized in thickness or locally changed in thickness as desired.
(C) Control in the directions of the width and length:
[0061] Referring to FIGs. 13 and 14, there is illustrated an embodiment of the invention with a construction such that one of anode sheets, on the copper foil-recovering side, is partly divided into sub-anodes for controlling foil thickness widthwise (hereinafter called "sub-anodes in the direction of the width") 4 and sub-anode for controlling foil thickness lengthwise (hereinafter called "sub-anodes in the direction of the length") 9. Suitable number of sub-anodes in the direction of the width 4', 4'', .....and sub-anodes in the direction of the length 9', 9'' ...... are formed. These sub-anodes in the directions of the width and length may be arranged in whatever order desired. The sub-anodes in the direction of the length may be replaced by a single sub-anode not divided in the direction of the width.
[0062] FIG. 15 shows another embodiment in which sub-anodes 9 in the direction of the length are provided in a plurality of rows throughout the remainder except for sub-anodes 4 in the direction of the width of the anode sheet 3 on the copper foil-recovering side. Each row of sub-anodes in the direction of the length may be replaced by a single sub-anode not divided widthwise.
[0063] FIG. 16 shows another embodiment constructed so that not only the anode sheet on the copper foil-recovering side but also the sheet on the electrodeposition-starting side is partly provided with sub-anodes in the direction of the length.
[0064] The larger the number of division in the direction of the width and the number of rows of the sub-anodes the more precisely the control can be exercised. Greater difficulties will be involved, however, in fabrication and maintenance. Generally, depending on the width of the copper foil to be made and on the conditions of the foil production equipment used, one anode is divided into from 10 to 40 sub-anodes per row.
[0065] As already explained, some apparatus for producing electrolytic copper foil show the tendency of producing a foil unusually thin in the central zone or conversely along at least one edge portion. To cope with this, it may be found expedient to divide the middle portion or at least one edge portion, as the case may be, of at least one, or a part of one, of the anode sheets, on the copper foil-recovering side, widthwise into a plurality of sub-anodes for controlling foil thickness.
[0066] As can be seen from the foregoing, in such equipment, it is desirably possible to selectively to make a central portion thinner or to make an end portion thinner or further to desirably change the thickness of a specific portion in the direction of the width and in the direction of the length.
[0067] FIG. 17 illustrates yet another embodiment in which only the middle portion of one anode sheet, on the copper foil-recovering side, is divided widthwise into sub-anodes 4 and FIG. 18 is an embodiment in which the both edge portions of one anode sheet are divided widthwise into sub-anodes 4. The both embodiments have sub-anodes 9 in the direction of the length provided at the upper ends. Needless to say, in FIGs. 17 and 18, the sub-anodes in the direction of the width may form a part of the anode and, specifically in FIG. 18, either edge portion alone may be so divided. The choice depends on the conditions of the particular copper foil production equipment used.
[0068] The operational manner of electrolytic copper foil production is according to the previous explanations.
[0069] As the cathode drum rotates, electrodeposition of copper from the electrolyte starts, approximately at 3 o'clock position, and the deposit thickness increases until it attains a desired thickness at about 9 o'clock position where the electrodeposition comes to an end. The foil of the desired thickness is peeled off by suitable peeler means at about 12 o'clock position and wound up.
[0070] Taking the case where variation in thickness is caused as an example also herein, an explanation is made. As stated above, localized variation in thickness in the directions of the length and the width of the untreated foil results from factors such as the lack of uniformity of the flow velocity of the electrolyte being fed or of the supply of electricity.
[0071] In the embodiments being described, the thickness in the direction of the width of the untreated foil is determined after the peeling and, when the thickness variation has exceeded a permissible limit in any sections, electric currents supplied to the specific sub-anodes 4 in the direction of the width corresponding to the specific sections are controlled independently of one another so as to correct the variation widthwise.
[0072] As for the control in the direction of the length, the thickness patterns per revolution of the cathode drum of a sample of the actually formed copper foil is measured at some points lengthwise and widthwise. According to the measured results, a plurality of sub-rectifiers 7 adjust the current supplied between the individual sub-anodes and the cathode drum.
[0073] For the purposes of the invention the expression "the thickness pattern per revolution of the cathode drum" is used to mean the variation in thickness of the copper foil formed upon one complete turn of the cathode drum measured, e.g., at 720 points chosen by dividing the copper foil area by 36 lengthwise and by 20 widthwise, and then calculating as 36× 20 = 720.
[0074] The variation in thickness of the copper foil is decreased as the number of the division in the directions of the length and the width is increased. When the maintenance of the control means and other considerations for the above purpose are taken into account, a number in the range from 10 to 40 is usually satisfactory.
[0075] To permit the individual control of the sub-anodes 4, sub-rectifiers 7 are connected between the individual sub-anodes 4 and the cathode drum 1. Likewise, although not shown, other sub-rectifiers are connected between the individual sub-anodes 9 and the cathode drum 1.
[0076] Also in this embodiment, the individual sub-anodes for controlling foil thickness widthwise and lengthwise can also be controlled through the control of their set positions in the similar manner as previously explained.
[0077] Thus, under this embodiment, an electrolytic copper foil being manufactured can be made controlled in thickness widthwise and lengthwise including uniformity in thickness and any local change as desired in thickness by the use of sub-anodes for controlling the foil thickness widthwise and sub-anodes for controlling the foil thickness lengthwise, through the individual control of either the quantities of electricity supplied to the sub-anodes or the set positions of the individual sub-anodes.
(D) Pattern control
[0078] According to this embodiment, the thickness in the directions of the length and width of the untreated foil is determined after the peeling and, when variation in the target thickness has exceeded a permissible limit, the quantities of electricity supplied to sub-anodes for controlling foil thickness is individually controlled so as to eliminate it on the basis of a combined pattern combining a thickness pattern in the direction of the length and a thickness pattern in the direction of the width.
[0079] Referring to FIGs. 19 and 20, there is illustrated an embodiment of the invention with a construction such that one of anode sheets, on the copper foil-recovering side, is partly divided into sub-anodes for controlling foil thickness (hereinafter called "sub-anodes") 20. Suitable number of sub-anodes 20', 20'' .....are formed.
[0080] FIG. 21 shows another embodiment in which sub-anodes 20 are provided in a plurality of rows throughout the anode sheet 3 on the copper foil-recovering side.
[0081] FIG. 22 shows another embodiment built so that not only the anode sheet 3 on the copper foil-recovering side but also the anode sheet 3 on the electrodeposition-starting side is partly provided with sub-anodes 20.
[0082] The larger the number of the division in the direction of the width and the number of rows of the sub-anodes the more precisely the control can be exercised. Greater difficulties will be involved, however, in fabrication and maintenance. Generally, depending on the width of the copper foil to be made and on the conditions of the foil production equipment used, one anode is divided into from 10 to 40 sub-anodes per row.
[0083] As stated above, localized variation in thickness in the directions of the length and the width of the untreated foil results from factors such as changes in the spacing between the anode and the cathode, the lack of uniformity of the flow velocity of the electrolyte being fed or of the supply of electricity.
[0084] In the embodiments being described, the thickness in the directions of the length and the width of the untreated foil is determined after the peeling and, when the thickness variation from the target thickness has exceeded a permissible limit, electric currents supplied to the sub-anode are controlled, on the basis of a combined pattern combining a thickness pattern in the direction of the length and a thickness pattern in the direction of the width, so as to correct the variation.
[0085] To be more exact, it is desirable that the thickness pattern per revolution of the cathode drum of a sample of the actually formed copper foil be determined beforehand and, on the basis of the pattern so determined, the quantity of electricity supplied to the sub-anodes be controlled.
[0086] For the purposes of the invention the expression "the thickness pattern per revolution of the cathode drum" is used to mean any variation from the target thickness (for example, fluctuations in thickness) of the copper foil formed upon one complete turn of the cathode drum measured, e.g., at 720 points chosen by dividing the copper foil area by 36 lengthwise and by 20 widthwise, and then calculating as 36 × 20 = 720. It represents the combination of a thickness pattern in the direction of the length and a thickness pattern in the direction of the width.
[0087] The case in which the thickness of a copper foil is measured beforehand at a total of 720 points as chosen above will now be explained.
[0088] Any variation from the target thickness (for example, fluctuations in thickness) at the 720 points, as noted above, represent those caused by irregularities, such as lack of uniformity of the cathode-anode spacing, the flow rate of electrolyte fed, and the quantity of electricity supplied. They indirectly represent the relations between a given portion of the cathode drum and the anode during one complete turn of the particular portion round the drum along a given track thereon (the relations given in terms of changes in the spacing, electrolyte flow rate, quantity of electricity supplied, etc.) and therefore represent the variation in thickness.
[0089] It follows that, in order to obtain a copper foil having a predetermined thickness, it is only necessary to decide and control the quantities of electricity to be supplied to the individual sub-anodes in conformity with the thickness variation pattern from the target thickness of the 720 points. The thickness of the copper foil being produced is monitored and, when a change beyond a permissible limit has taken place, the electricity supplied to the corresponding portion of the variation pattern is controlled. In this way a copper foil having a predetermined thickness in the directions of the length and the width can be obtained.
[0090] A single row of sub-anodes usually will do, but where the variation is beyond control with a single row or where more precise control is needed, a plurality or a number of rows may be provided instead.
[0091] To permit the individual control of the sub-anodes 20, sub-rectifiers 7 are connected between the individual sub-anodes 20 and the cathode drum 1.
[0092] The individual sub-anodes can also be controlled through the control of their set positions as explained before.
[0093] Thus, under this embodiment, an electrolytic copper foil being manufactured can be made controlled in thickness including uniformity in thickness or any change as desired in thickness by the use of sub-anodes based on the combination of a thickness pattern in the direction of the length and a thickness pattern in the direction of the width through the individual control of either the quantities of electricity supplied to the sub-anodes or the set positions of the individual sub-anodes.
[0094] As be apparent from the foregoing, this invention not only permits to effectively uniformize the thickness of a copper foil, but also permits to change or modify as desired the thickness of the copper foil in a given portion or portions in the directions of the length and the width. This invention intend to comprehend all these embodiments.
[0095] Examples of this invention are set forth below. It is noted that these examples do not intend to restrict this invention.
[Example A-1]
[0096] A 35 µm-thick copper foil was made using a copper sulfate solution and a combination of a cathode drum 2.0 m in diameter and 1.3 m in width and two 1.3 m-wide sheets of anode arranged arcuately along substantially the lower half of the cathode drum as shown. The anode structure according to the invention was as depicted in FIGs. 2 and 3 and comprised 20 sub-anodes. On the basis of the weight values per unit area of the peeled copper foil, the electric currents supplied to the individual sub-anodes were adjusted within the range of 0.1 to 10 A/dm². Thus, the method of the invention made it possible to reduce the variation in thickness widthwise, from the usual level of about 3% down to 0.5% or less.
[Example A-2]
[0097] The anode structure embodying the invention comprised, 20 sub-anodes arranged on the existing anode sheet as shown in FIG. 1 on the copper foil-recovering side. Otherwise in the same way as in Example A-1, a 35µm-thick copper foil was made. The variation in thickness widthwise of the copper foil thus obtained was 0.5% or less.
[Example B-1]
[0098] A 35 µm-thick copper foil was made using a copper sulfate solution and a combination of a cathode drum 2.0 m in diameter and 1.3 m in width and two 1.3 m-wide sheets of anode arranged arcuately along substantially the lower half of the cathode drum as shown. The anode structure according to the invention was as depicted in FIGs. 9 and 10 and a longitudinally divided anode comprised 20 sub-anodes.
[0099] On the basis of a lengthwise thickness pattern per revolution of the cathode drum that had been determined beforehand (at 20 widthwise × 36 lengthwise = 720 points), the electric currents supplied to the individual sub-anodes were calculated with a personal computer and adjusted within the range of 0.1 to 10 A/dm². Thus, the method of the invention made it possible to reduce the variation in thickness lengthwise, from the usual level of about 3% down to 0.5% or less.
[Example B-2]
[0100] The anode structure embodying the invention comprised, a longitudinally divided anode sheet consisting of 20 sub-anodes arranged on the existing anode sheet as shown in FIG. 1 on the copper foil-recovering side. Otherwise in the same way as in Example B-1, a 35µm-thick copper foil was made. The variation in thickness lengthwise of the copper foil thus obtained was 0.5% or less.
[Example C-1]
[0101] A 35 µm-thick copper foil was made using a copper sulfate solution and a combination of a cathode drum 2.0 m in diameter and 1.3 m in width and two 1.3 m-wide sheets of anode arranged arcuately along substantially the lower half of the cathode drum as shown. The anode structure according to the invention, as depicted in FIGs. 13 and 14, comprised of sub-anodes 20 widthwise and 20 lengthwise.
[0102] On the basis of a thickness pattern in the direction of the length per revolution of the cathode drum that had been determined beforehand (at 20 widthwise× 36 lengthwise = 720 points), the electric currents supplied to the individual sub-anodes were calculated with a personal computer and adjusted within the range of 0.1 to 10 A/dm². Thus, the method of the invention made it possible to reduce the variation in thickness in the directions of the length and the width, from the usual level of about 3% down to 0.5% or less.
[Example C-2]
[0103] The anode structure embodying the invention comprised, a longitudinally divided anode sheet consisting of sub-anodes in the directions of the width and the length, 20 each, arranged on the existing anode sheet as shown in FIG. 1 on the copper foil-recovering side. Otherwise in the same way as in Example C-1, a 35 µm thick copper foil was made. The variation in thickness in the direction of the length and in the direction of the width of the copper foil thus obtained was 0.5% or less.
[Example D-1]
[0104] A 35 µm-thick copper foil was made using a copper sulfate solution and a combination of a cathode drum 2.0 m in diameter and 1.3 m in width and two 1.3 m-wide sheets of anode arranged arcuately along substantially the lower half of the cathode drum as shown. The anode structure according to the invention, as depicted in FIGs. 19 and 20 comprised 20 sub-anodes.
[0105] On the basis of the combination of thickness patterns in the directions of the length and the width per revolution of the cathode drum that had been determined beforehand (at 20 widthwise × 36 lengthwise = 720 points), the electric currents supplied to the individual sub-anodes were calculated with a personal computer and adjusted within the range of 0.1 to 10 A/dm². Thus, the method of the invention made it possible to reduce the variation in thickness lengthwise and widthwise, from the usual level of about 3% down to 0.5% or less.
[Example D-2]
[0106] The anode structure embodying the invention comprised, 20 sub-anodes arranged on the existing anode sheet as shown in FIG. 1 on the copper foil-recovering side. Otherwise in the same way as in Example D-1, a 35µm-thick copper foil was made. The variation in thickness in the direction of the length and in the direction of the width of the copper foil thus obtained was 0.5% or less.
Advantage of the invention
[0107] The present invention permits to uniformize or change or modify as desired the thickness of an electrolytic copper foil using foil thickness-controlling sub-anodes in the direction of the width or the length or both thereof by individually controlling either of the quantities of electricity supplied to the sub-anodes or the set positions of the sub-anodes. Thus, the present invention can accommodate the requirements for electrolytic copper foils for electronic devices and others in future.