FIELD OF THE INVENTION
[0001] The present invention is related to a method for manufacturing an ink jet printhead,
and more particularly to a device for manufacturing an ink jet printhead.
BACKGROUND OF THE INVENTION
[0002] Ink jet printers play an important role in printing field. Although they are put
into application before laser jet printers, the use of laser jet printers does not
supersede ink jet printers because of their increasingly high resolution and potential
in color printing. The ink jet printhead is the most important part in an ink jet
printer because it is crucial to printing performance and quality.
[0003] Please refer to Fig. 1 which is a schematic diagram showing a typical ink jet printhead.
The main part of the printhead is a chip 1 including circuits which are used for receiving
signals generated from the computer through the software program operation, and controlling
the ink-ejecting operation in accordance with the received signals. In the center
of the chip 1 is a through hole 2 for restoring the ink 21. There are many ink-containing
holes 3 provided around through hole 2. The plurality of ink-containing holes 3 are
communicated with the through hole 2 so ink 21 contained in through hole 2 can flow
into the ink-containing holes 3. A nozzle plate 4 having many nozzles 41 thereon covers
ink-containing holes 3 wherein the plurality of nozzles 41 respectively correspond
to the plurality of ink-containing holes 3.
[0004] Please refer to Fig. 2 which is a sectional diagram showing an ink-containing hole
and its peripheral structure. The ink-containing hole 3 is formed by photolithographing
a photoresist 31. The chip 1 has a heating element. When a printing instruction is
given, the circuits of chip 1 control the heating- element to heat ink 21 restrained
in ink-containing hole 3, and then ink 21 will be ejected through the nozzle 41 of
the nozzle plate 4. Thus, it can be seen that the nozzle 41 must be small enough so
that the amount of ejected ink 21 can be controlled well and high resolution of the
ink jet printer can be anticipated.
[0005] Please refer to Figs. 3(a)-(d) which are schematic diagrams showing a conventional
process for manufacturing an ink jet printhead. Fig. 3(a) shows the first step of
forming a photoresist 31 on the chip 1 followed by the next step of forming a plurality
of ink-containing holes 3 on the chip 1 by photolithographing the photoresist 31 as
shown in Fig. 3(b). Then, a hard baking step is executed in order to reduce the solvent
in the photoresist 31. For bonding the nozzle plate 4 and the chip 1, the adhesive
5 is coated right above the photoresist 31 as shown in Fig. 3(c). Fig. 3(d) shows
that the nozzle plate 4 is placed on the adhesive 5. It must be noted that the plurality
of nozzles 41 are in vertical alignment with the plurality of ink-containing holes
3 respectively so the ink can be ejected smoothly through the nozzle 41. At last,
the chip 1 accompanied with the nozzle plate 4 is transferred to a heating chamber
to be heated to bond the chip 1 and the nozzle plate 4 together firmly. It is difficult
to operate this prior method because such a tiny element requires an extremely small
amount of adhesive 5. The small amount of adhesive is not easily controllable. Too
much adhesive chokes the small nozzle and the ink can not be ejected. On the other
hand, too less adhesive can not bond the chip and the nozzle plate properly so the
nozzle plate will fall down or the ink will leak out. Moreover, the adhesive-coating
instrument is very expensive, but the rejection rate is as high as fifty percents.
It really wastes too much production cost.
[0006] Before the chip and the nozzle plate are moved to the heating chamber, the fixing
step is also important because a careless fixing will cause a relative displacement
between the chip and the nozzle plate. When the semiconductor manufacturing process
is progressed into the sub-micron field, such a careless mistake is not allowable
because it results in failure of the element. Sometimes, a simple clip is used for
fixing the chip and the nozzle plate, but the force exerted by the clip can not be
controlled. Usually, a press gripper is used in fixing wafers. Please refer to Fig.
4 which is a schematic diagram of a conventional fixing facility. The nozzle plate
4 is placed on the chip 1 and is fixed by a press gripper 6. The press gripper 6 includes
a bottom 61, contact mediums 62, a cylinder 63, and an air-supplying pipe 64. The
air-supplying pipe 64 supplies a controlled amount of air into the cylinder 63, and
the upper contact medium 62 presses down to fix the nozzle plate 4 on the chip 1.
This kind of fixing device can control the exerted force on the nozzle plate 4 by
controlling the flow rate of the supplied air. Different forces are exerted n view
of different strengths of the chip 1 and the nozzle plate 4. But, it is possible that
the introduced force on the nozzle plate 4 is not a normal force. It will thus cause
a relative displacement between the chip 1 and the nozzle plate 4. Besides, if the
exerted forces on the two sides of the nozzle plate 4 are not balanced, these elements
still can not be fixed well due to the resulting inclination of these elements.
SUMMARY OF THE INVENTION
[0007] An objective of the present invention is to provide a method for manufacturing an
ink jet printhead with high yield rate.
[0008] Another objective of the present invention is to provide a device for manufacturing
an ink jet printhead with high yield rate.
[0009] In accordance with the objective of the present invention, a method for manufacturing
an ink jet printhead which includes a plurality of ink-containing holes for containing
therein an ink, a nozzle plate having thereon a plurality of nozzles corresponding
to the plurality of ink-containing holes for ejecting therethrough the ink, and a
chip for controlling the ejection of the ink, includes steps of (a) forming a photo-sensitive
layer on the chip, (b) forming the plurality of ink-containing holes on the photo-sensitive
layer, (c) placing the nozzle plate on the photo-sensitive layer, and (d) heating
the photo-sensitive layer to bond the chip and the nozzle plate.
[0010] In accordance with another aspect of the present invention, the photo-sensitive layer
is certainly a photoresist.
[0011] In accordance with another aspect of the present invention, the photoresist is a
dry photoresist. The thickness of the formed photoresist is preferably from 50 µm
to 1000 µm.
[0012] In accordance with another aspect of the present invention, the photoresist is a
wet photoresist. The thickness of the formed photoresist is preferably from 0.1 µm
to 50 µm.
[0013] In accordance with another aspect of the present invention, the plurality of ink-containing
holes are formed by photolithography.
[0014] In accordance with another aspect of the present invention, the photo-sensitive layer
is heated by a hot plate under a heat temperature from 100 °C to 250 °C for a heat
period form 1 minute to 10 hours.
[0015] In accordance with another aspect of the present invention, the heating step (d)
farther includes a step of (d1) exerting a pressure from 0.01 kg/cm
2 to 1 kg/cm
2 on the nozzle plate to prompt the step (d) of bonding the chip and the nozzle plate.
[0016] In accordance with another aspect of the present invention, the plurality of nozzles
are respectively in vertical alignment with the corresponded ink-containing holes.
[0017] In accordance with another aspect of the present invention, the step (c) further
includes a step of (c1) fixing the nozzle plate on the chip.
[0018] In accordance with another aspect of the present invention, the nozzle plate is fixed
on the chip by a clip.
[0019] In accordance with another aspect of the present invention, the fixing step (c1)
farther includes steps of (c11) placing the nozzle plate and the chip on a base wherein
a through hole in the chip is right above a flute on the base, and (c12) vacuumizing
the flute for fixing the nozzle plate by a sucking force.
[0020] In accordance with another aspect of the present invention, an vacuumized pressure
in the flute is preferably less than a surrounding pressure from 50 mmHg to 200 mmHg.
[0021] In accordance with another aspect of the present invention, the nozzle plate is a
metal plate such as a nickel plate.
[0022] In accordance with the objective of the present invention, a method for manufacturing
an ink jet printhead which includes a plurality of ink-containing holes for containing
therein an ink, a nozzle plate having thereon a plurality of nozzles for ejecting
therethrough the ink, and a chip for controlling the ejection of the ink, includes
steps of (a) placing the chip on a base wherein a through hole in the chip is right
above a flute on the base, (b) coating an adhesive on the chip, (c) placing the nozzle
plate on the chip, (d) vacuumizing the flute for fixing the nozzle plate by a sucking
force, and (e) heating the adhesive to bond the chip and the nozzle plate.
[0023] In accordance with another aspect of the present invention, the base further includes
a plurality of independent flutes which have different vacuumized pressures.
[0024] In accordance with another aspect of the present invention, the method includes,
after the step (e), a step of (f) de-vacuumizing the flute for removing the sucking
force.
[0025] In accordance with another objective of the present invention, a device for manufacturing
an ink jet printhead which includes a nozzle plate for ejecting therethrough an ink,
and a chip mounted below the nozzle plate for controlling the ejection of the ink
and having therein a through hole, includes a base and a flute provided on the base
having an opening communicating with the flute, and a vacuum apparatus communicating
with the opening. The base is used for supporting thereon the chip wherein the through
hole is right above the flute. The vacuum apparatus is used for vacuumizing the flute
to fix the nozzle plate to the chip by a sucking force.
[0026] In accordance with another aspect of the present invention, the flute can be a straight
flute or an annular flute.
[0027] In accordance with another aspect of the present invention, the vacuum apparatus
is preferably a rotary vacuum pump.
[0028] In accordance with another aspect of the present invention, the device further includes
a three-way valve mounted between the vacuum apparatus and the opening for controlling
the sucking force. The valve communicates the flute with the vacuum apparatus for
vacuumizing the flute to exert the sucking force in a first instance. And the valve
communicates the flute with surroundings for de-vacuumizing the flute to remove the
sucking force in a second instance.
[0029] The present invention may best be understood through the following description with
reference to the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0030]
Fig. 1 is a schematic diagram showing a typical ink jet printhead;
Fig. 2 is a sectional diagram showing an ink-containing hole and its peripheral structure;
Figs. 3(a)-(d) are schematic diagrams showing a conventional process for manufacturing
an ink jet printhead;
Fig. 4 is a schematic diagram of a conventional fixing medium.;
Figs. 5(a)-(c) are schematic diagrams showing a preferred embodiment of a method for
manufacturing an ink jet printhead according to the present invention;
Fig. 6 is a schematic diagram showing another preferred embodiment of the printhead-manufacturing
method according to the present invention; and
Fig. 7 is a schematic diagram showing a preferred embodiment of a fixing device according
to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0031] The present invention will now be described more specifically with reference to the
following embodiments. It is to be noted that the following descriptions of preferred
embodiments of this invention are presented herein for the purpose of illustration
and description only; it is not intended to be exhaustive or to be limited to the
precise form disclosed.
[0032] The present invention provides a method for manufacturing an ink jet printhead more
rapidly. Please refer to Fig. 5 which is a schematic diagram showing a preferred embodiment
of a method for manufacturing the ink jet printhead according to the present invention.
At first, coat a photoresist 31 on the chip 1 as shown in Fig. 5(a). The photoresist
31 is made from a known photo-sensitive material and has no other limitations. The
photoresist is typically classified into dry photoresist or wet photoresist according
to the amount of solvent in the photoresist. The dry type is applicable to thicker
photoresist with thickness from 50 µm to 1000 µm while the other type is applicable
to thinner photoresist with thickness from 0.1 µm to 50 µm. The dry type is the most
often used one because the thickness range is suitable for containing the ink. The
coating step is executed by spin-coating because the obtained photoresist is especially
smooth by this method.
[0033] Please refer to Fig. 5(b). The next step is to photolithograph the photoresist 31
to form the ink-containing hole 3. The steps including soft baking, exposure, and
development are executed in sequence to form a plurality holes, so-called ink-containing
holes 3, on the photoresist 31. According to the prior art, the next step should be
hard-backing step for evaporating the solvent in the photoresist 31 in order to adhere
the photoresist 31 to the chip 1 more firmly. But the photoresist 31 is not gluey
after dried so another adhesive is needed for bonding the nozzle plate 4 to the chip
1. Please refer to Fig. 5(c), According to the present invention, the conventional
hard baking step is suspended temporarily. Before the photoresist 31 is dried, place
the nozzle plate 4 on the photoresist 31 wherein each nozzle 41 is in alignment with
its corresponding ink-containing hole 3. Then, the hard baking step is resumed.
[0034] Hard baking step is used for reducing the amount of solvent in the photoresist 31.
This step can make the photoresist 31 adhere to the chip 1 and the nozzle plate 4
properly. The photoresist 31 is heated by conduction. In other words, a hot plate
is adopted. The heat temperature and heat period are determined according to the material
of photoresist 31. Typically, the heat temperature is from 100 °C to 250 °C while
the heat period is from 1 minute to 10 hours. Too low a heat temperature requires
a longer period of time to evaporate the solvent. Too high a heat temperature causes
a worse adhesion of the photoresist due to much tensile stress stored in it. It is
difficult to fully evaporate the solvent in the photoresist if the heating period
is too short. On the other hand, the photoresist becomes fragile if the heat period
is too long. For the above reasons, the heat temperature and the heating period must
be determined properly. Besides, an additional pressure from 0.01 kg/cm
2 to 1 kg/cm
2 can be exerted on the nozzle plate 4 to prompt the bonding of nozzle plate 4 and
chip 1.
[0035] Certainly, the production efficiency can be increased by slightly modifying the present
technology. Heretofore, because of the limit of the adhesive-coating step, the manufacturers
can not manufacture many ink jet printheads at a particular period of time. They must
bond the first nozzle plate on the first chip, then bond the second nozzle plate on
the second chip, and so on. If a wafer has thereon one hundred chips, the bonding
step must be repeated for one hundred times. It is impossible to coat an adhesive
on all of the chips included in one wafer at first, and then place all the nozzle
plates on the wafer because the adhesive-coating step is a time-consuming step. The
coated adhesive will dry before all the nozzle plates are placed on the wafer. On
the contrary, the method according to the present invention can manufacture many ink
jet printheads at a time. A metal plate having hundreds of nozzle plates is placed
on the photoresist above the wafer having hundreds of chips before the photoresist
is dried. Then, the metal plate accompanied with the wafer is heated and all hundreds
of nozzle plates and chips are bonded together. Apparently, this method can speed
up the production efficiency.
[0036] Compared with the prior art, the present invention eliminates the adhesive-coating
step so that the process consumes less time. Moreover, the present invention can even
bond hundreds of nozzle plates and chips at the same time so that the process consumes
much less time. Besides, eliminating the adhesive-coating step also eliminates the
troubles, such as choke of the nozzle, leakage of the ink, or falling of the nozzle
plate, resulting from an improper amount of the adhesive occurred during the adhesive-coating
step. The rejection rate will be reduced to zero if the nozzles of the nozzle plates
are really in alignment of the ink-containing holes on the chips. The expensive adhesive-coating
instrument is not needed any more so this method saves not only production time but
also production cost.
[0037] The fixing device is also improved according to the present invention. If the nozzle
plates are not fixed properly on the chips, the above-described efforts are in vain
because there is a relative displacement between the nozzle plates and the chips before
we heat the photoresist. Please refer to Fig. 6 which is a schematic diagram showing
another preferred embodiment of the printhead-manufacturing method according to the
present invention. The wafer 8 including many chips 1 is placing on the base 71 wherein
the through holes 2 of the chips 1 are right above the flute 72 of the base 71. After
the photoresist is coated on the chips 1, the metal plate 9 including many nozzle
plates 4 is placed on the wafer 8 wherein the nozzles of the nozzle plates 4 are in
vertical alignment with the ink-containing holes of the chips 1 as described in the
prior preferred embodiment. Before heating the photoresist located between the metal
plate 9 and the wafer 8, the metal plate 9 and the wafer 8 must be fixed firmly so
there is no relative displacement between them when they are translated. The vacuum
apparatus 73 communicating with the opening 721 of the base 71 vacuumizes the flute
72 and a sucking force is generated to fix the metal plate 9 to the wafer 8. The vacuum
apparatus 73 is a rotary vacuum pump. A three-way valve 74 can be added to control
the sucking force. If the sucking force is desired, the three-way valve 74 is caused
to communicate the rotary vacuum pump 73 with the flute 72 and the rotary vacuum pump
73 vacuumizes the flute 72. After the heating step, the metal plate 9 and the wafer
8 are bonded together so the sucking force can be removed. Consequently, the three-way
valve 74 communicates the flute 72 with the surroundings and the flute 72 is de-vacuumized
so the sucking force is removed. When the rotary vacuum pump 73 works, the pressure
difference between the flute 72 and the surroundings is from 50 mmHg ∼ 200 mmHg. The
greater the pressure difference is, the greater the sucking force is. The pressure
difference is determined by the vacuuming power of the rotary vacuum pump 73 in accordance
with the strength of the metal plate 9. It is noted that although a great pressure
difference can fix the metal plate 9 more firmly, too great a pressure difference
will cause damage to the metal plate 9.
[0038] Certainly, it is not necessary that all the through holes 2 are right above the flute
72. The generation of sucking force is not affected if some through holes 2 are not
right above the flute 72.
[0039] Certainly, the fixing method is also practicable if there are a plurality of flutes
on the base, or the flute is otherwise shaped. Please refer to Fig. 7 which is a schematic
diagram showing a preferred embodiment of the fixing device according to the present
invention. The flutes 72 are annular flutes. Each flute 72 corresponds to a rotary
vacuum pump 73 and a three-way valve 74. Accordingly, the pressure differences between
the flutes 72 and the surroundings may be different. For example, if the strength
of the metal plate is not equable, the exerted sucking forces must be different at
different points of the metal plate. Thus, proper sucking forces can be exerted at
any point of the metal plate by respectively controlling the vacuuming powers of each
rotary vacuum pump 73.
[0040] The present fixing method used for manufacturing the ink jet printhead is better
than the prior art. The manufacturers need not worry about other forces which are
not normal to the metal plate are introduced according to the prior art. The best
advantage is that the force strength can be adjusted arbitrarily at any point. The
manufacturers also need not worry that the metal plate is not fixed well or the metal
plate is damaged because of improper exerted forces. Moreover, the sucking force is
uniform for the whole metal plate according to the present invention while the sucking
force is not uniform according to the prior art because strains are only generated
at the points where the clips or the grippers are added. Such improper fixing will
cause deformation of the metal plate and the wafer. Accordingly, the present method
is more utilizable due to its easily controlled characteristics.
[0041] While the invention has been described in terms of what are presently considered
to be the most practical and preferred embodiments, it is to be understood that the
invention need not be limited to the disclosed embodiment. On the contrary, it is
intended to cover various modifications and similar arrangements included within the
spirit and scope of the appended claims which are to be accorded with the broadest
interpretation so as to encompass all such modifications and similar structures.
1. A method for manufacturing an ink jet printhead, said ink jet printhead including
a plurality of ink-containing holes for containing therein an ink, a nozzle plate
having thereon a plurality of nozzles corresponding to said plurality of ink-containing
holes for ejecting therethrough said ink, and a chip for controlling the ejection
of said ink, comprising:
(a) forming a photo-sensitive layer on said chip;
(b) forming said plurality of ink-containing holes on said photo-sensitive layer;
(c) placing said nozzle plate on said photo-sensitive layer; and
(d) heating said photo-sensitive layer to bond said chip and said nozzle plate.
2. A method according to claim 1 wherein in said step (a), said photo-sensitive layer
is a photoresist.
3. A method according to claim 2 wherein said photoresist is a dry photoresist having
a thickness from 50 µm to 1000 µm.
4. A method according to claim 2 wherein said photoresist is a wet photoresist having
a thickness from 0.1 µm to 50 µm.
5. A method according to claim 2 wherein in said step (b), said plurality of ink-containing
holes are formed by photolithography.
6. A method according to claim 1 wherein in said step (d), said photo-sensitive layer
is heated by a hot plate under a heat temperature for a heat period.
7. A method according to claim 6 wherein said heat temperature is from 100 °C to 250
°C.
8. A method according to claim 6 wherein said heat period is from 1 minute to 10 hours.
9. A method according to claim 1 wherein said step (d) further comprises a step of (d1)
exerting a pressure on said nozzle plate to prompt said step (d) of bonding said chip
and said nozzle plate.
10. A method according to claim 9 wherein said pressure is from 0.01 kg/cm2 to 1 kg/cm2.
11. A method according to claim 1 wherein in said step (c), said plurality of nozzles
are respectively in vertical alignment with said corresponded ink-containing holes.
12. A method according to claim 1 wherein said step (c) further comprises a step of (c1)
fixing said nozzle plate on said chip.
13. A method according to claim 12 wherein in said step (c1), said nozzle plate is fixed
on said chip by a clip.
14. A method according to claim 12 wherein said step (c1) further comprises steps of:
(c11) placing said nozzle plate and said chip having therein a through hole on a base
having thereon a flute, said through hole being right above said flute; and
(c12) vacuumizing said flute for fixing said nozzle plate by a sucking force.
15. A method according to claim 14 wherein in said step (c12), an vacuumized pressure
in said flute is less than a surrounding pressure from 50 mmHg to 200 mmHg.
16. A method according to claim 1 wherein said nozzle plate is a metal plate.
17. A method according to claim 16 wherein said metal plate is a nickel plate.
18. A method for manufacturing an ink jet printhead, said ink jet printhead including
a nozzle plate having thereon a plurality of nozzles for ejecting therethrough an
ink, and a chip for controlling the ejection of said ink, comprising:
(a) placing said chip having therein a through hole on a base having thereon a flute,
said through hole being right above said flute;
(b) coating an adhesive on said chip;
(c) placing said nozzle plate on said chip;
(d) vacuumizing said flute for fixing said nozzle plate by a sucking force; and
(e) heating said adhesive to bond said chip and said nozzle plate.
19. A method according to claim 18 wherein said base further includes a plurality of independent
flutes.
20. A method according to claim 19 wherein said plurality of independent flutes have different
vacuumized pressures.
21. A method according to claim 18 wherein after said step (e), said method further comprises
a step of (f) de-vacuumizing said flute for removing said sucking force.
22. A device for manufacturing an ink jet printhead, said ink jet printhead including
a nozzle plate for ejecting therethrough an ink, and a chip mounted below said nozzle
plate for controlling the ejection of said ink and having therein a through hole,
comprising:
a base supporting thereon said chip and a flute provided on said base having an opening
communicating with said flute, said through hole being right above said flute; and
a vacuum apparatus communicating with said opening for vacuumizing said flute to fix
said nozzle plate to said chip by a sucking force.
23. A device according to claim 22 wherein said flute is a straight flute.
24. A device according to claim 22 wherein said flute is an annular flute.
25. A device according to claim 22 wherein said vacuum apparatus is a rotary vacuum pump.
26. A device according to claim 22 wherein said device further comprises a three-way valve
mounted between said vacuum apparatus and said opening for controlling said sucking
force, said valve communicating said flute with said vacuum apparatus for vacuumizing
said flute to exert said sucking force in a first instance and communicating said
flute with surroundings for de-vacuumizing said flute to remove said sucking force
in a second instance.