JP3794161B2 - Inkjet head manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electrostatic actuator type inkjet head.
[0002]
[Prior art]
Conventionally, as an electrostatic actuator type inkjet head, for example, an inkjet head 100 shown in FIG. 5 has been proposed. The inkjet head 100 is configured by integrally joining a cover plate 12, a channel plate 14, and a substrate 16.
[0003]
The channel plate 14 is made of a silicon plate, and a plurality of grooves are formed by anisotropic etching. By covering these groove portions with the cover plate 12, the ink channel 18 that stores ink, the nozzle 22 that discharges ink in the ink channel 18 as droplets, and the common ink that stores ink supplied to the ink channel 18, respectively. The chamber 26 and the inlet 30 that connects the ink channel 18 and the common ink chamber 26 are provided.
[0004]
The bottom of the ink channel 18 is a diaphragm 19, and a common electrode 34 is formed on the surface of the diaphragm 19 opposite to the ink channel 18. On the other hand, a shallow recess 36 extending along the longitudinal direction of the ink channel 18 (left and right in FIG. 5) is formed on the substrate 16, and a drive electrode 38 is formed in the recess 36 so as to face the common electrode 34. ing.
[0005]
In the inkjet head 100 configured as described above, when voltages having different polarities are applied to the common electrode 34 and the drive electrode 38, the diaphragm 19 bends toward the drive electrode 38 because the electrodes 34 and 38 are attracted by electrostatic attraction force. Deform. Due to this deformation, the volume in the ink channel 18 is increased, and accordingly, ink is drawn from the common ink chamber 26 to the ink channel 18 through the inlet 30. When the voltage application to the electrodes 34 and 38 is released, the diaphragm 19 returns to the state before deformation due to its own elasticity. At this time, the ink in the ink channel 18 is pressurized, and ink droplets are ejected from the nozzles 22.
[0006]
[Problems to be solved by the invention]
However, in the inkjet head 100, since the gap g between the common electrode 34 and the drive electrode 38 is set to be very narrow, for example, 0.2 μm, the surface irregularities of the drive electrode 38 formed by printing, sputtering, or the like. Even when the head is very small, the drive electrode 38 may come into contact with the common electrode 34 when the head is assembled or when the diaphragm 19 is deformed, causing an electrical short circuit, which makes it impossible to use the head.
[0007]
Further, as shown in FIG. 5, since the surfaces of the drive electrode 38 and the substrate 16 become the bonding surfaces with the channel plate 14, there is a problem that the bonding strength is lowered when the surface roughness of the drive electrodes 38 and the substrate 16 is rough. there were.
[0008]
[Means for Solving the Problems]
Therefore, in order to solve the above problems, the present invention provides a nozzle, an ink flow path communicating with the nozzle, a vibration plate provided in a part of the ink flow channel, and a vibration plate provided on the vibration plate. A first substrate having an electrode and a second substrate having a counter electrode provided opposite to the diaphragm electrode are joined, and a pulse voltage is applied between the diaphragm electrode and the counter electrode. In the method of manufacturing an inkjet head, the diaphragm is deformed by electrostatic force, and the ink droplets are ejected from the nozzles toward the recording paper by the deformation.
The counter electrode is formed so as to rise from the recess in the recess formed in the second substrate, and the surface of the counter electrode is polished so as to have a predetermined surface roughness together with the recess forming surface of the second substrate. Thereafter, the second substrate is bonded to the first substrate.
[0009]
In this inkjet head manufacturing method, the surface roughness of the polished surface of the second substrate and the counter electrode is preferably several nanometers or less.
[0010]
【The invention's effect】
According to the ink jet head of the present invention, since each surface of the counter electrode and the second substrate is polished to a predetermined surface roughness, the second substrate is bonded to the first substrate. When the head is assembled or the diaphragm is deformed, the counter electrode is less likely to come into contact with the diaphragm electrode. As a result, the electrical short circuit between the electrodes is reduced, and the yield and reliability of the head are improved.
[0011]
In addition, since the smoothness of the bonding surface is improved by polishing the surfaces of the counter electrode and the second substrate, the bonding strength is increased when the second substrate and the first substrate are anodically bonded, and the integrated object And almost the same strength can be obtained.
[0012]
Furthermore, if the surface roughness of the polished surface of the second substrate and the counter electrode is several nanometers or less, the effects of preventing short circuit between the electrodes and improving the bonding strength at the time of assembling the head can be further ensured. .
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of an ink jet head 10 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the ink jet head 10 of FIG. 1 and 2, the cross-hatched portion indicates an electrode portion. The ink jet head 10 is formed by laminating a cover plate 12, a channel plate (first substrate) 14 and a substrate (second substrate) 16 and integrally bonding them.
[0013]
The cover plate 12 is a silicon plate, for example, and covers the upper part of the channel plate 14. The channel plate 14 is made of, for example, a silicon plate, and a plurality of grooves are formed on its upper surface by anisotropic etching. Specifically, a plurality of long grooves 20 that form ink channels (ink flow paths) 18 are arranged in parallel to each other. In addition, V-shaped narrow grooves 24 serving as the nozzles 22 are formed on the edge of the channel plate 14 so as to communicate with the long grooves 20. Further, a lateral groove 28 serving as a common ink chamber 26 extends along the arrangement direction of the plurality of long grooves 20 in the vicinity of the edge of the channel plate 14 opposite to the V-shaped narrow groove 24. The long groove 20 serving as the ink channel 18 and the lateral groove 28 serving as the common ink chamber 26 are communicated with each other by a V-shaped narrow groove 32 serving as an inlet 30. By covering these groove portions 20, 24, 28 and 32 with the cover plate 12, the ink channel 18, the nozzle 22, the common ink chamber 26 and the inlet 30 are formed.
[0014]
The nozzle 22 communicates with the ink channel 18 and discharges ink in the ink channel 18. Further, the ink channel 18 and the common ink chamber 26 communicate with each other via an inlet 30, and ink is supplied from the common ink chamber 26 to each ink channel 18 and stored therein. Further, the common ink chamber 26 is connected to an ink tank (not shown), and ink is supplied therefrom.
[0015]
The bottom of the ink channel 18 is a diaphragm 19. The layer including the diaphragm 19 extending to the edge of the channel plate 14 is given conductivity by boron doping and functions as a common electrode (diaphragm electrode) 34. On the other hand, on the surface of the substrate 16 made of glass or the like, a plurality of shallow recesses 36 are formed corresponding to the ink channels 18. The depth of the recess 36 is preferably 0.3 μm or more and 30 μm or less. A driving electrode (counter electrode) 38 is formed in each recess 36. The drive portion 38a of the drive electrode 38 and the common electrode 34 face each other with a gap of 0.2 μm ± 0.0015 μm. As shown in FIG. 1, the drive electrode 38 is wide at the drive portion 38a corresponding to the ink channel 18 and the electrical connection portion 38b, and is narrow at the portion 38c therebetween. The common electrode 34 and the plurality of drive electrodes 38 are electrically connected to the drive circuit 40 from the respective rear end portions.
[0016]
Next, a method for manufacturing the ink jet head 10 having the above configuration will be described with reference to FIGS.
As shown in FIG. 3, in manufacturing the substrate 16, first, a glass substrate 50 is prepared (FIG. 3A), and the glass substrate 50 is etched to form a recess 36 (FIG. 3B). Next, a metal electrode slurry is applied to the recess 36 by pad printing or screen printing to form the drive electrode 38. At this time, the drive electrode 38 rises from the recess 36 (FIG. 3C). Therefore, the substrate 16 is completed by polishing and smoothing the surface of the drive electrode 38 thus raised to a predetermined surface roughness together with the recess forming surface 16a of the substrate 16 (FIG. 3D). The surface roughness at this time is preferably several nanometers or less. More specifically, the surface roughness can be reduced to 1 nanometer or less by using a polishing method called super polish (Shin-Etsu Quartz Co., Ltd.).
[0017]
As shown in FIG. 4, in the manufacture of the channel plate 14, first, a silicon plate 52 is prepared (FIG. 4A), and a lower layer 52 a having a thickness of 0.2 μm is left from the lower surface of the silicon plate 52. A common electrode layer 34 is formed by boron doping the layer adjacent to the lower layer 52a (FIG. 4B). The common electrode layer 34 also functions as an etching stop layer. Next, etching is performed from the upper surface of the silicon plate 52 to form a plurality of grooves to be the nozzle 22, the ink channel 18, the inlet 30, and the common ink chamber 26 (FIG. 4C). Thereafter, a portion of the lower layer 52a of the silicon plate 52 facing the ink channel 18 is removed by etching to form a gap portion 54 where the common electrode 34 and the drive electrode 38 face each other, thereby completing the channel plate 14 ( FIG. 4 (d)). Subsequently, the silicon cover plate 12 is joined to the upper portion of the channel plate 14 by diffusion bonding (FIG. 4E). Finally, the inkjet head 10 is completed by bonding the substrate 16 to the lower surface of the channel plate 14 by anodic bonding (FIG. 4F).
[0018]
Next, the ink ejection operation of the inkjet head 10 having the above configuration will be described. Ink supplied from an ink tank (not shown) to the common ink chamber 26 is accommodated in each ink channel 18 via a corresponding inlet 30. In this state, when a pulse voltage is applied from the drive circuit 40 to the drive electrode 38, the common electrode 34 to which a voltage having a polarity different from the pulse voltage is applied is attracted by electrostatic force, and the diaphragm 19 is driven to the drive electrode 38. Deforms into a convex shape toward Due to this deformation, the volume in the ink channel 18 increases, and accordingly, ink is drawn from the common ink chamber 26 into the ink channel 18 through the inlet 30. When the voltage application to the drive electrode 38 is released, the diaphragm 19 returns to its pre-deformation state due to its own elasticity, whereby the ink in the ink channel 18 is pressurized and the ink droplets are ejected from the nozzles 22. Is discharged. The ink droplets adhere to a recording medium such as paper (not shown) to form dots, and an image is recorded by the set of dots.
[0019]
As described above, according to the method for manufacturing the inkjet head 10 of the present embodiment, the substrate 16 is bonded to the channel plate 14 after the surface of the drive electrode 38 is polished to a predetermined surface roughness. When the diaphragm 19 is deformed, the drive electrode 38 is less likely to come into contact with the common electrode 34. As a result, an electrical short circuit between the electrodes 34 and 38 is reduced, and the yield and reliability of the head are improved.
[0020]
In addition, since the smoothness of the bonding surface is improved by polishing the surfaces of the drive electrode 38 and the substrate 16, the bonding strength is increased when the substrate 16 and the channel plate 14 are anodically bonded, which is almost the same as that of the integrated object. Strength is obtained.
[0021]
Further, by making the surface roughness of the polished surfaces of the substrate 16 and the drive electrode 38 to be several nanometers or less, it is possible to further ensure the effects of preventing short circuit between the electrodes and improving the bonding strength during head assembly. .
[0022]
Furthermore, in the inkjet head 10, the drive electrode 38 can be formed thick according to the depth of the recess 36 of the substrate 16. By forming the drive electrode 38 thick, the resistance value can be reduced, whereby the discharge of residual charges can be accelerated, so that the drive frequency can be increased, and as a result, the printing speed can be increased.
[0023]
In the above-described embodiment of the present invention, the boron doping layer including the diaphragm 19 of the channel plate 14 is used as the common electrode 34. However, a metal thin film is formed on the surface of the channel plate 14 facing the substrate by sputtering. May be used as a common electrode.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of an inkjet head.
FIG. 2 is a partial cross-sectional view of the assembled ink jet head of FIG.
FIG. 3 is a process diagram showing a manufacturing process of a substrate.
FIG. 4 is a process diagram showing a manufacturing process of an inkjet head.
FIG. 5 is a partial cross-sectional view showing an example of a conventional inkjet head.
[Explanation of symbols]
14 ... Channel plate (first substrate), 16 ... Substrate (second substrate), 18 ... Ink channel (ink flow path), 19 ... Vibration plate, 22 ... Nozzle, 34 ... Common electrode (vibration plate electrode), 38: Drive electrode (counter electrode).

Claims (2)

A first substrate having a nozzle, an ink channel communicating with the nozzle, a diaphragm provided in a part of the ink channel, and a diaphragm electrode provided on the diaphragm; and the diaphragm A second substrate having a counter electrode provided opposite to the electrode, and a pulse voltage is applied between the diaphragm electrode and the counter electrode to deform the diaphragm by electrostatic force, In the method of manufacturing an ink jet head for performing printing by discharging ink droplets from the nozzles toward the recording paper by deformation,
The counter electrode is formed so as to rise from the recess in the recess formed in the second substrate, and the surface of the counter electrode is polished so as to have a predetermined surface roughness together with the recess forming surface of the second substrate. Thereafter, the second substrate is bonded to the first substrate. A method for manufacturing an ink jet head, comprising: 2. The method of manufacturing an ink jet head according to claim 1, wherein the surface roughness of the polishing surface of the second substrate and the counter electrode is several nanometers or less.

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