JP2019059078A - Ink jet head, manufacturing method of the ink jet head, and image forming device - Google Patents

Abstract

To provide an ink jet head which can prevent peeling and disconnection of wiring on a substrate having the wiring for driving an ink chamber.SOLUTION: An ink jet head includes: a nozzle substrate with a plurality of nozzles formed thereon; a pressure chamber substrate on which a pressure chamber for communicating with the respective nozzles is formed; a drive electrode arranged on the pressure chamber; a wiring substrate which has a first through hole and a second through hole and is arranged by adhering to the pressure chamber substrate on an opposite side to the nozzle substrate; and wiring which is connected to the drive electrode at a connection surface of the wiring substrate facing to a pressure chamber substrate side, and is arranged in a state that it is led out to a rear surface with respect to the connection surface through the first through hole, and is led out to the connection surface through the second through hole. In the wiring, thicknesses of parts arranged on inner walls of the first through hole and the second through hole are thinner than parts arranged on the connection surface and the rear surface.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an inkjet head, a method of manufacturing an inkjet head, and an image forming apparatus provided with the inkjet head.

  As an image forming apparatus using an ink jet head, a nozzle plate having a plurality of nozzles bored therein, an ink chamber forming member provided with a plurality of ink chambers communicating with each nozzle, and a sidewall of each ink chamber Some are provided with individually provided drive electrodes. In the image forming apparatus having such a configuration, the side wall of the ink chamber is deformed as a driving wall by applying a signal to the driving electrode, and thereby the ink in the ink chamber is ejected from the nozzle.

  Further, in such an image forming apparatus, a substrate having a wire for applying a signal to drive electrodes provided corresponding to each ink chamber is provided in a state of being attached to an ink chamber forming member. The following Patent Document 1 describes a configuration in which a first through hole and a second through hole are provided in this substrate. According to this configuration, the first wiring electrically connected to the individual electrode provided on each drive electrode is drawn from the ink chamber forming member side through the first through hole to the opposite surface of the substrate. Then, the ink is further pulled back to the ink chamber forming member through the second through hole. As a result, wiring using both sides of the substrate becomes possible, and the degree of freedom of the wiring route is improved.

JP 2014-226787

  In recent years, high definition of an image to be formed is required for an image forming apparatus, and the density of nozzles and an ink chamber of an inkjet head has been advanced. For this reason, in the image forming apparatus having the above-described configuration, densification and miniaturization are also required for the first through hole and the second through hole. However, in the driving of the ink jet head, the heat generated by the driving of the ink chamber generates a stress due to the difference in the linear expansion coefficient between the wiring and the substrate material. In particular, in the insides of the first through holes and the second through holes which are miniaturized, the generated stress tends to be large, which causes the peeling and disconnection of the wiring.

  Therefore, the present invention provides an ink jet head capable of preventing peeling and disconnection of wiring on a substrate having a wiring for driving an ink chamber, a method of manufacturing the ink jet head, and an image forming apparatus provided with the ink jet head. Intended to be provided.

  The present invention for achieving such an object comprises a nozzle substrate having a plurality of nozzles formed therein, a pressure chamber substrate having a pressure chamber communicating with each of the nozzles, and a drive electrode provided in the pressure chamber. A wiring board having a first through hole and a second through hole and provided on the pressure chamber substrate on the side opposite to the nozzle substrate, and a wiring substrate facing the pressure chamber substrate in the wiring substrate The connection surface is connected to the drive electrode, drawn to the back surface to the connection surface through the first through hole, and further disposed to be drawn to the connection surface through the second through hole. And the wiring has a film thickness of a portion disposed on the inner wall of the first through hole and the second through hole than a film thickness of a portion disposed on the connection surface and the back surface. It is a thin inkjet head . The present invention is also an image forming apparatus provided with a method of manufacturing such an inkjet head and an inkjet head.

  According to the present invention configured as described above, in a substrate having a wiring for driving an ink chamber, an ink jet head capable of preventing peeling and disconnection of the wiring, a method of manufacturing the ink jet head, and the ink jet head Can be obtained.

FIG. 1 is a view showing a schematic configuration of an image forming apparatus according to an embodiment. FIG. 2 is a bottom view of a head unit provided in the image forming apparatus according to the embodiment. It is a disassembled perspective view of the principal part of the ink jet head concerning a 1st embodiment. FIG. 2 is a cross-sectional view of the main part of the ink jet head according to the first embodiment. It is a top view of the pressure chamber substrate in the ink jet head concerning a 1st embodiment. It is a top view of the wiring substrate in the ink jet head concerning a 1st embodiment. It is sectional drawing to which the principal part of the inkjet head concerning 1st Embodiment was expanded. It is sectional drawing which shows the modification 1 of 1st Embodiment. It is sectional drawing which shows the modification 2 of 1st Embodiment. It is sectional drawing to which the principal part of the inkjet head concerning 2nd Embodiment was expanded. It is sectional drawing to which the principal part of the inkjet head concerning 3rd Embodiment was expanded. It is an enlarged plan view of the principal part of the wiring board in the ink jet head concerning a 4th embodiment. It is sectional drawing to which the principal part of the inkjet head concerning 4th Embodiment was expanded. It is a manufacturing-process figure of the wiring board of the inkjet head concerning 4th Embodiment.

  First, prior to the description of the image forming apparatus according to each embodiment to which the present invention is applied, a schematic configuration of the image forming apparatus common to each embodiment of the present invention will be described using FIG. The structure of the ink jet head which has the same structure and the method of manufacturing the same will be described. In the respective embodiments, the same components are denoted by the same reference numerals, and the description of the same components will be omitted.

<< Schematic Configuration of Image Forming Apparatus >>
FIG. 1 is a schematic view showing an inkjet type image forming apparatus according to the embodiment. The image forming apparatus 200 shown in this figure includes a sheet feeding unit 210, an image recording unit 220, and a sheet discharging unit 230. Such an image forming apparatus 200 conveys the recording medium M stored in the paper feeding unit 210 to the image recording unit 220, forms an image on the recording medium M in the image recording unit 220, and forms the image on the image M is conveyed to the paper discharge unit 230. Among these, the image recording unit 220 has an inkjet head which is characteristic in the embodiment.

  That is, the image recording unit 220 includes a transport drum 221, a delivery unit 222, a heating unit 223, a head unit 224 including an inkjet head, a fixing unit 225, a delivery unit 226, and the like. These configurations are as follows.

<Conveyance drum 221>
The conveyance drum 221 has a cylindrical shape, and the side circumferential surface thereof is a conveyance surface on which the recording medium M is placed. The transport drum 221 transports the recording medium M along the transport surface by rotating in the direction of the arrow in FIG. 1 with the recording medium M held on the transport surface.

<Delivery unit 222>
The delivery unit 222 is provided at a position between the medium supply unit 212 of the paper feeding unit 210 and the conveyance drum 221. The delivery unit 222 holds one end of the recording medium M conveyed from the medium supply unit 212, and delivers the pickup conveyance drum 221 also onto the conveyance surface.

<Heating unit 223>
The heating unit 223 is provided between the delivery unit 222 and the head unit 224, and heats the recording medium M so that the temperature of the recording medium M conveyed by the conveyance drum 221 becomes a temperature within a predetermined temperature range. Such a heating unit 223 is configured using, for example, an infrared heater or the like, and the infrared heater is energized to perform heating based on a control signal supplied from a control unit (not shown).

<Head unit 224>
The head unit 224 ejects ink to the recording medium M at an appropriate timing according to the rotation of the transport drum 221 holding the recording medium M based on the image data to form an image. The head unit 224 is disposed with its ink ejection surface facing the transport surface of the transport drum 221 at a predetermined distance. In the image forming apparatus 200 of the present embodiment, for example, four head units 224 respectively corresponding to four color inks of yellow (Y), magenta (M), cyan (C), and black (K) Are arranged at predetermined intervals in the order of Y, M, C, and K from the upstream side in the transport direction.

  FIG. 2 is a bottom view of the head unit 224 provided in the image forming apparatus according to the embodiment, and is a view of the head unit 224 of FIG. 1 viewed from the conveyance drum 221 side. As shown in FIG. 2, the head unit 224 has a plurality of inkjet heads 100 arrayed along a bottom surface 224 a facing the transport drum 221. In the illustrated example, the pair of inkjet heads 100 is one set, and a plurality of sets (here, eight sets) of inkjet heads 100 are arranged in two rows in a zigzag.

  The configuration of the ink jet head 100 will be described in detail below, but the discharge opening 100 a of the nozzle of the ink jet head 100 is disposed on the bottom surface 224 a of the head unit 224. Such a head unit 224 is used in a state of being fixed at a predetermined position with respect to the rotation axis of the conveyance drum 221.

<Fixing Unit 225>
Returning to FIG. 1 again, the fixing unit 225 is provided downstream of the arrangement position of the head unit 224 and upstream of the delivery unit 226 in the conveyance direction of the recording medium M. The fixing unit 225 has a light emitting unit disposed across the width direction of the transport drum 221, and irradiates energy rays such as ultraviolet light from the light emitting unit to the recording medium M placed on the transport surface to place the recording medium M on. The ink jetted to the ink is cured and fixed.

<Delivery Unit 226>
The delivery unit 226 is provided downstream of the fixing unit 225 and upstream of the delivery unit 222 in the transport direction of the recording medium M. The delivery unit 226 conveys the recording medium M delivered from the conveyance drum 221 and delivers the recording medium M to the paper discharge unit 230.

«Ink jet head relating to the first embodiment»
Next, the configuration of the inkjet head 101 according to the first embodiment provided in the head unit 224 of the image forming apparatus 200 described above will be described.

  FIG. 3 is an exploded perspective view of the main part of the ink jet head according to the first embodiment. FIG. 4 is a cross-sectional view of the main part of the ink jet head according to the first embodiment. As shown in FIGS. 3 and 4, the inkjet head 101 according to the first embodiment includes the nozzle substrate 1, the pressure chamber substrate 2, the wiring substrate 3, and the manifold 4 in order from the bottom side of the head unit. There is. Further, on the pressure chamber substrate 2 side of the wiring substrate 3, a flexible substrate 5 is provided. Among these, in the first embodiment, the wiring provided on the wiring substrate 3 is characteristic. Hereinafter, these components will be described in order, and then the characteristic configuration of the wiring of the wiring board 3 and the method of manufacturing the wiring board 3 will be described in order.

<Nozzle substrate 1>
The nozzle substrate 1 is a long thin plate-like substrate member, and includes a plurality of nozzles 1 a penetrating the substrate member in the thickness direction. Each nozzle 1a is formed as a hole for discharging the ink to the side of the transport drum 221 shown in FIG. In the nozzle 1a, for example, the side wall is formed in a tapered shape so that the opening diameter decreases from the pressure chamber substrate 2 side toward the bottom surface side of the head unit described above. Such a nozzle substrate 1 constitutes a part of the bottom surface of the head unit.

<Pressure chamber substrate 2>
The pressure chamber substrate 2 is a long substrate member, and includes a plurality of pressure chambers 2 a penetrating the substrate member in the thickness direction. It is a space portion provided as a channel for storing ink, and is a space as an ink chamber in which application of pressure is possible to the ink stored inside. Each of the pressure chambers 2a has a substantially rectangular opening shape and is provided so as to communicate with the nozzles 1a provided on the nozzle substrate 1.

  FIG. 5 is a plan view of the pressure chamber substrate in the ink jet head according to the first embodiment, and is a plan view of the connection surface S2a when the main surface facing the wiring substrate 3 is the connection surface S2a. The cross-sectional view shown in FIG. 4 corresponds to the A-A 'cross section in FIG.

  As shown in this figure, the plurality of pressure chambers 2a are arranged at a predetermined pitch along the short side direction of the substantially rectangular opening shape. Here, the pressure chambers 2a are provided in four rows, and the pressure chambers 2a in the odd-numbered rows and the pressure chambers 2a in the even-numbered rows are arranged to be shifted by a half pitch in the row direction.

  As described above, in the pressure chamber substrate 2 in which the pressure chambers 2a are arranged, a partition portion sandwiched by two pressure chambers 2a arranged in the column direction constitutes a drive wall. Drive electrodes for driving partition walls between adjacent pressure chambers 2a as drive walls on the inner wall in the row direction of each pressure chamber 2a, that is, the inner wall of a portion corresponding to the long side of the substantially rectangular opening shape 21 are disposed to face each other so as to sandwich at least a partition portion. Thus, the pressure chamber substrate 2 is provided with a piezoelectric element in which a partition between two pressure chambers 2a is sandwiched by the drive electrodes 21. The piezoelectric elements and the pressure chambers 2a are alternately arranged.

  In the pressure chamber substrate 2 having such a configuration, when a voltage is applied to the drive electrode 21, the partition portion between the adjacent pressure chambers 2a functions as a drive wall and repeats shear mode type displacement, whereby the pressure chamber 2a is formed. The pressure is applied to the ink. In the illustrated example, the drive electrodes 21 are provided to cover the wall surfaces in three directions out of the wall surfaces in four directions that constitute the inner wall of the pressure chamber 2a.

  The pressure chamber substrate 2 as described above is provided with the individual electrodes 21 a drawn from the drive electrodes 21 as a part of the drive electrodes 21 on the connection surface S 2 a facing the wiring substrate 3. Each of the individual electrodes 21a is extended in the direction perpendicular to the row direction of the pressure chambers 2a from the short side located near the outer periphery of the connection surface S2a among the short sides of the substantially rectangular opening shape in the pressure chambers 2a. ing. These individual electrodes 21a may be extended by about the same length regardless of the arrangement position of the pressure chamber 2a.

  Although each individual electrode 21a is also a part of the drive electrode 21, the drive electrode 21 and the individual electrode 21a may be integrally formed or may be individually formed. Good.

<Wiring board 3>
As shown in FIGS. 3 and 4, the wiring substrate 3 is provided in a state of being bonded to the connection surface S2 a of the pressure chamber substrate 2. The pressure chamber substrate 2 and the wiring substrate 3 are bonded to each other by an anisotropic conductive adhesive 6. The wiring substrate 3 is formed of a flat rectangular substrate member which is slightly larger than the pressure chamber substrate 2, and the pressure is applied to the entire periphery of the pressure chamber substrate 2 in a state of being bonded to the pressure chamber substrate 2. It has a size protruding from the chamber substrate 2.

  When such a wiring board 3 has the main surface on the side facing the pressure chamber substrate 2 as the connection surface S3a to the pressure chamber substrate 2 and the main surface on the opposite side as the back surface S3b, the connection surface S3a and the back surface S3b The ink flow path 3a and the wiring hole 3b which penetrate between are provided. The wiring board 3 further includes a connection surface S3a, a back surface S3b, and a wire 31 formed on the inner wall of the ink flow path 3a and the wiring hole 3b.

  FIG. 6 is a plan view of the wiring substrate in the ink jet head according to the first embodiment, and is a plan view of the connection surface S3a of the wiring substrate 3 facing the pressure chamber substrate 2. FIG. The cross-sectional view shown in FIG. 4 corresponds to the A-A 'cross section in FIG. Next, the configuration of the ink flow path 3a, the wiring hole 3b, and the wiring 31 of the wiring substrate 3 will be described with reference to FIG. 6 and FIGS. 3 to 4 described above.

[Ink flow path 3a]
The ink flow path 3 a is a first through hole provided in the wiring substrate 3, and in the wiring substrate 3 bonded to the pressure chamber substrate 2, at each position corresponding to the pressure chamber 2 a of the pressure chamber substrate 2. It is provided. Each of the ink flow paths 3a has a substantially rectangular opening shape, and communicates with the pressure chambers 2a individually in a state where the pressure chamber substrate 2 and the wiring substrate 3 are bonded to each other. For this reason, in the wiring substrate 3, a plurality of ink flow paths 3a are arranged in four rows along the short side direction of the substantially rectangular opening shape, and the ink flow paths 3a in the odd rows and the even rows The ink flow paths 3a are arranged at a half pitch offset in the column direction.

  Each ink passage 3a communicates with a common ink chamber 4a of a manifold 4 to be described next, thereby individually connecting the common ink chamber 4a and each pressure chamber 2a.

  The ink flow path 3a as described above has an opening shape slightly smaller than the opening shape of the pressure chamber 2a, and the opening area S1 of the ink flow path 3a which is the first through hole is the opening area of the pressure chamber 2a. For S2, for example, S2> S1. Thereby, when the low viscosity ink is used, the overflow of the meniscus from the tip of the nozzle 1a can be suppressed. Depending on the viscosity of the ink, S2 ≦ S1 may be satisfied.

[Wiring hole 3b]
The wiring hole 3 b is a second through hole provided in the wiring substrate 3, and the wiring substrate 3 bonded to the pressure chamber substrate 2 is a position protruding from the pressure chamber substrate 2, and the ink flow path It arranges in the further outer side of the arrangement | sequence of the both ends of 3a, and is provided. Each wiring hole 3b is provided in accordance with the arrangement of the ink flow path 3a. That is, the wiring holes 3b arranged on both sides of the ink flow path 3a are arranged with a half pitch offset in the column direction with respect to the ink flow path 3a of the adjacent row. The shape of the opening of each wiring hole 3 b is not particularly limited, as long as the wiring can be formed in the hole to reach the main surfaces on both sides of the wiring substrate 3.

[Wiring 31]
The wiring 31 is a wiring for connecting the drive electrode 21 provided on the pressure chamber substrate 2 to the flexible substrate 5 via the wiring substrate 3, and is provided corresponding to each ink flow path 3a. There is. Each wire 31 is connected to the drive electrode 21 at the individual electrode 21 a provided on the connection surface S 2 a of the pressure chamber substrate 2 by the anisotropic conductive adhesive 6.

  These wirings 31 are classified into two types by the row in which the ink flow path 3a is disposed. That is, among the four lines of ink flow paths 3a, the lines 31 provided corresponding to the ink flow paths 3a arranged in two lines at both ends are referred to as the first lines 31a. Among the four rows of ink flow paths 3a, ones provided corresponding to the ink flow paths 3a arranged in the two inner rows are set as a second wiring 31b.

  Among these, the first wirings 31 a corresponding to the ink flow paths 3 a arranged in the columns at both ends may be arranged only on the connection surface S 3 a of the wiring substrate 3. Each first wiring 31a is extended from the position facing the individual electrode 21a of the pressure chamber 2a to the end edge of the connection surface S3a of the wiring substrate 3, specifically the position where the flexible substrate 5 is bonded. Since the first wiring 31a is formed in the same procedure as the second wiring 31b described below, it is also provided on the inner wall and the back surface S3b of the ink flow path 3a as shown in FIG. It may be done.

  The second wiring 31 b corresponding to the ink flow path 3 a arranged in the inner row is connected to the individual electrode 21 a of the drive electrode 21 by the conductive adhesive 6 at the connection surface S 3 a of the wiring substrate 3. Furthermore, the second wiring 31b is drawn to the back surface S3b of the wiring substrate 3 through the inner wall of the ink flow path 3a which is the first through hole, and is laid on the back surface S3b. Furthermore, the second wiring 31b is drawn again to the connection surface S3a from the back surface S3b of the wiring substrate 3 via the inner wall of the wiring hole 3b which is the second through hole, and the edge of the connection surface S3a, specifically the flexible substrate 5 Is extended to the position where it is adhered.

  As described above, in the wiring 31, both the first wiring 31a and the second wiring 31b correspond to the pressure chambers 2a of the pressure chamber substrate 2 by the conductive adhesive 6 that bonds the pressure chamber substrate 2 and the wiring substrate 3 together. The drive electrode 21 is electrically connected at 1: 1.

  The wiring 31 configured as described above is a portion provided on the connection surface S3a and the back surface S3b of the wiring substrate 3 and an inner wall of the ink flow path 3a which is a first through hole and a second through hole. A feature is that the film thickness is different from the portion provided on the inner wall of the wiring hole 3b. The film thickness will be described in detail later.

<Manifold 4>
The manifold 4 shown in FIGS. 3 and 4 is a housing provided with a common ink chamber 4a. The manifold 4 is provided in a state of being attached to the back surface S3 b of the wiring substrate 3. The arrangement position of the manifold 4 with respect to the wiring substrate 3 is a position inside the arrangement of the wiring holes 3 b of the wiring substrate 3 and covering all the ink flow paths 3 a of the wiring substrate 3 with the common ink chamber 4 a. Although not shown here, it is assumed that an ink supply path for supplying ink into the common ink chamber 4 a is connected to the manifold 4. In addition, a heater for heating the ink in the common ink chamber 4 a to a viscosity that can be discharged from the nozzles 1 a of the nozzle substrate 1 may be provided on the outer periphery of the manifold 4.

<Flexible substrate 5>
The flexible substrate 5 shown in FIG. 3, FIG. 4 and FIG. 6 is a film-like substrate having flexibility, and is bonded to the connection surface S3a of the wiring substrate 3 at the position sandwiching the pressure chamber substrate 2. It is provided. The wiring substrate 3 and the flexible substrates 5 are bonded together by the anisotropic conductive adhesive 7 (see FIG. 4).

  Each flexible substrate 5 includes a plurality of wirings 51 on the main surface side facing the connection surface S3 a of the wiring substrate 3. The wirings 51 are electrically connected to the wirings 31 provided on the connection surface S3a of the wiring substrate 3 by 1: 1 by the anisotropic conductive adhesive 7.

<Features of Wiring 31 in Wiring Board 3>
FIG. 7 is an enlarged cross-sectional view of the main part of the ink jet head according to the first embodiment, which is a portion B in FIG. 4 and is an enlarged view of one of the ink channels 3a provided in the wiring substrate 3 and the periphery thereof. FIG. As shown in FIG. 7, in the ink jet head 101 of the first embodiment, the film thickness of the wiring 31 provided on the wiring substrate 3 has a partially different size. That is, the wiring 31 passes through the first penetration with respect to the film thickness t1 of the electrode portion 301 provided on the connection surface S3a of the wiring substrate 3 and the film thickness t2 of the back surface wiring portion 302 provided on the back surface S3b of the wiring substrate 3 The film thickness t3 of the inner wall wiring portion 303 provided on the inner wall of the ink flow path 3a which is a hole is thin. The same applies to the wiring hole 3b whose illustration is omitted here. Therefore, in the following, the ink flow path 3a will be illustrated and described, as a representative of the ink flow path 3a which is the first through hole and the wiring hole 3b which is the second through hole.

  The difference between the film thickness t1 of the electrode portion 301 and the film thickness t2 of the back surface wiring portion 302 and the film thickness t3 of the inner wall wiring portion 303 is not limited. The film thickness t1 of the electrode portion 301 and the film thickness t2 of the back surface wiring portion 302 may be thick as long as patterning is easy, and the inner wall wiring portion 303 is preferably thin as long as conductivity can be secured. As an example, the film thickness t1 of the electrode portion 301 is 3 μm, the film thickness t2 of the back surface wiring portion 302 is 3 μm, and the film thickness t3 of the inner wall wiring portion 303 is about 1.5 μm.

  The wiring 31 having the above film thickness may be made of the same material in each part, may be integrally formed with each other, or may be formed individually. In this case, the wiring 31 is made of, for example, a metal material such as gold (Au), titanium (Ti), chromium (Cr), nickel (Ni), aluminum (Al), copper (Cu) and the like. it can.

  It is preferable that the contact angle θ2 of the inner wall wiring portion 303 with the ink is smaller than the contact angle θ1 of the back surface wiring portion 302 with the ink. As a result, the initial introduction of the ink into the ink flow path 3a is easy, and it becomes difficult for bubbles to get in the ink flow path 3a, so that the amount of ink in the ink flow path 3a can be stabilized. In this case, the surface 31 of the inner wall wiring portion 303 is made to have a contact angle θ 2 with the ink by performing a hydrophilization treatment such as plasma treatment only on the surface of the inner wall wiring portion 303 formed in the ink flow path 3 a. , Can be smaller than other parts.

  Moreover, each part may be formed by the separate material of the wiring 31. FIG. In this case, the electrode portion 301 and the back surface wiring portion 302 are made of a metal material such as gold (Au), and the inner wall wiring portion 303 is made of a metal material such as aluminum (Al). Thus, the contact angle θ2 of the inner wall wiring portion 303 with the ink can be made smaller than the contact angle θ1 of the electrode portion 301 and the back surface wiring portion 302 with the ink.

<Method of Manufacturing Wiring Board 3>
The method of manufacturing the wiring substrate 3 provided with the wiring 31 as described above is, for example, as follows. First, after the ink flow path 3a and the wiring hole 3b are formed in the substrate material of the wiring substrate 3, the film formation of the wiring material film from the connection surface S3a and the film formation of the wiring material film from the back surface S3b are Do each individually according to the law. In the film formation of the wiring material film on the connection surface S3a and the back surface S3b by the vapor deposition method, the wiring material for the inner wall of the ink flow path 3a and the wiring hole 3b is thinner than the connection surface S3a and the back surface S3b. A film is formed. At this time, in one of the vapor deposition, the ink flow path 3a and the wiring hole 3b are closed with a resist pattern. Thereby, the wiring material film is formed on the connection surface S3a and the back surface S3b, and the wiring material film having a film thickness sufficiently smaller than that of the connection surface S3a and the back surface S3b is also formed on the inner walls of the ink flow path 3a and the wiring hole 3b. Be done. The wiring material film may be formed on the inner wall of the ink flow path 3a separately from the other portions. Furthermore, the film formation of the wiring material film for each portion may be performed by applying a plating method.

  Further, after forming the wiring material film as described above, the wiring material films formed on the connection surface S3a and the back surface S3b are respectively patterned by etching using, for example, a resist pattern as a mask, whereby the wiring 31 is formed. Form.

<Effect of First Embodiment>
In the inkjet head 101 according to the first embodiment described above, the wiring substrate 3 has a configuration in which the inner wall wiring portion 303 which is a part of the wiring 31 is provided in a state of covering the inner wall of the ink flow path 3a and the wiring hole 3b. is there. The wiring 31 is made of a metal material and generally made of a material having a large linear expansion coefficient. In such a configuration, the stress generated between the substrate material in the ink flow path 3a and the wiring hole 3b and the wiring 31 tends to be large due to the heat generation caused by the driving of the ink jet head 101. Therefore, as described in the first embodiment, the film thickness t3 of the inner wall wiring portion 303 provided to cover the inner wall of the ink flow path 3a is thinner than the film thicknesses t1 and t2 of the other portions of the wiring 31. Thus, it is possible to reduce the stress generated on the inner wall of the ink flow path 3a and the wiring hole 3b due to the heat generation. As a result, it is possible to prevent peeling and disconnection of the wiring 31 due to the driving of the ink jet head 101, to further increase the density of the ink flow path 3a and to achieve high definition of the formed image, and the ink jet head It is possible to improve the long-term reliability of 101.

  Further, the film thickness t3 of the inner wall wiring portion 303 provided so as to cover the inner wall of the ink flow channel 3a is made smaller than the film thicknesses t1 and t2 of the other portions of the wiring 31 so that the volume in the ink flow channel 3a Variation can be reduced. As a result, it is possible to suppress variations in the ejection frequency, the droplet amount, and the droplet velocity of the ink droplet ejected from the tip of the nozzle 1a, and this also enables high definition of the formed image.

«Modified example 1 of the first embodiment»
FIG. 8 is a cross-sectional view showing a modified example 1 of the first embodiment. As shown in this figure, the ink jet head 101a of the modification 1 is provided with an insulating film 32 so as to cover the exposed portion of the wiring 31 provided on the wiring substrate 3. The insulating film 32 has the wiring substrate 3 and the pressure chamber substrate 2 in a state where the wiring substrate 3 provided with the wiring 31 and the pressure chamber substrate 2 provided with the drive electrode 21 are bonded by the conductive adhesive 6. It is formed in the state which covers the exposed part of. Therefore, the inner wall of the ink flow path 3 a is also covered, including the exposed portions of the wiring 31 and the drive electrode 21. Such an insulating film 32 is preferably made of a resin material. Although not shown here, the inner wall of the wiring hole 3b is also covered with the insulating film 32 in the same manner.

  According to such a configuration, since the exposed portion of the wiring 31 is covered by the insulating film 32, peeling of the wiring 31 in the wiring substrate 3 can be prevented. Further, by forming the insulating film 32 with a resin material, the insulating film 32 has elasticity, so that the influence of the thermal expansion of the insulating film 32 can be prevented from affecting the wiring 31 and the peeling of the wiring 31 is further effective. Can be prevented.

«Modification 2 of the first embodiment»
FIG. 9 is a cross-sectional view showing a modification 2 of the first embodiment. In the inkjet head 101b of the modification 2 shown in this figure, at least a part of the wiring 31 'provided on the wiring substrate 3 has a laminated structure. For example, as illustrated, in the wiring 31 ′, the electrode portion 301 provided on the connection surface S3a of the wiring substrate 3 has a stacked structure of the lower layer film 301a and the upper layer film 301b. Similarly, the back surface wiring portion 302 provided on the back surface S3b of the wiring substrate 3 has a laminated structure of the lower layer film 302a and the upper layer film 302b. Further, the inner wall wiring portion 303 provided on the inner wall of the ink flow path 3a has a smaller number of lamination than the electrode portion 301 and the back surface wiring portion 302, and here has a single layer structure. Although not shown here, the inner wall wiring portion 303 provided on the inner wall of the wiring hole 3b also has the same configuration as the inner wall wiring portion 303 provided on the inner wall of the ink flow path 3a.

  In this case, each film constituting the wiring 31 ′ may be a film made of the same constituent material and a different composition, but may be a film made of different constituent materials and a different composition. For example, the contact angle to the ink of each portion of the wiring 31 ′ may be adjusted by making the inner wall wiring portion 303 of the single layer structure made of a different constituent material with respect to the upper layer film 302b of the back surface wiring portion 302. . In this case, the inner wall wiring portion 303 having a single layer structure may be made of the same constituent material formed in the same step as the lower layer film 301a of the electrode portion 301 or the lower layer film 302a of the back surface wiring portion 302.

  According to the configuration of the second modification as described above, the control of the film thickness of each portion of the wiring 31 ′ can be facilitated. Therefore, the variation in the volume in the ink flow path 3a can be further effectively reduced.

Second Embodiment
FIG. 10 is an enlarged cross-sectional view of the main part of the ink jet head according to the second embodiment. The inkjet head 102 of the second embodiment shown in this figure is different from the inkjet head 101 of the first embodiment in the inner wall wiring portion 303-2 provided in the ink flow path 3a in the wiring 31 of the wiring substrate 3. The other configuration is the same as that of the first embodiment including the modification. Therefore, the configuration of the inner wall wiring portion 303-2 will be described here.

  The inner wall wiring portion 303-2 of the wiring 31 is larger in film thickness on the back surface S3b side of the wiring substrate 3 than on the connection surface S3a side of the wiring substrate 3. For example, although the film thickness of the inner wall wiring portion 303-2 is gradually increased from the connection surface S3a side to the back surface S3b side as illustrated, it may be stepwise.

  The film thickness t3 of the inner wall wiring portion 303-2 having such a shape is smaller than the film thickness t1 of the electrode portion 301 and the film thickness t2 of the back surface wiring portion 302, as in the first embodiment. In this case, the film thickness t3 of the inner wall wiring portion 303-2 may be the average film thickness of the film thickness from the connection surface S3a side of the wiring substrate 3 to the back surface S3b side. The inner wall wiring portion 303-2 provided on the inner wall of the wiring hole 3b (not shown here) may be the same as the inner wall wiring portion 303-2 provided in the ink flow path 3a. It is not limited to

<Method of Manufacturing Wiring Board 3>
The formation of the wiring 31 provided with such an inner wall wiring portion 303-2 is, for example, when depositing the wiring material from the back surface S3b, more deposition material is deposited on the back surface S3b of the ink flow path 3a. It is carried out by adjusting the deposition angle to Then, the deposition of the wiring material from the connection surface S3a is performed in a state in which the inside of the ink flow path 3a is closed with a resist pattern. Then, after forming the wiring material film as described above, the wiring material films formed on the connection surface S3a and the back surface S3b are respectively patterned by etching using, for example, a resist pattern as a mask, whereby the wiring 31 is formed. Form.

<Effect of Second Embodiment>
In the inkjet head 102 according to the second embodiment described above, the film thickness of the inner wall wiring portion 303-2 of the wiring substrate 3 is closer to the back surface S3b of the wiring substrate 3 than the connection surface S3a side of the wiring substrate 3, that is, FIG. And in the common ink chamber 4a shown in FIG. As a result, the heat in the ink flow path 3a, which is generated especially when the ink jet head 102 is driven, can be dissipated to the ink stored in the common ink chamber 4a. Therefore, in addition to the effects of the first embodiment, the heat generation in the ink flow path 3a can be further suppressed small, and the stress generated on the inner wall of the ink flow path 3a can be reduced. As a result, it is possible to more effectively prevent peeling and disconnection of the wiring 31 due to the drive of the inkjet head 102, and it is possible to improve the long-term reliability of the inkjet head 102.

Third Embodiment
FIG. 11 is an enlarged cross-sectional view of the main part of the ink jet head according to the third embodiment. The ink jet head 103 of the third embodiment shown in this figure differs from the ink jet head 101 of the first embodiment in the shape of the ink flow path 3a-3 of the wiring substrate 3, and the other configuration includes the modification. Is the same as the first embodiment. Therefore, the shape of the ink flow path 3a-3 will be described here.

  The ink flow path 3a-3 of the wiring substrate 3 has the smallest opening diameter at the middle position in the depth direction, and the inner wall is all around so that the opening diameter gradually increases toward the connection surface S3a side and the back surface S3b side. Is formed in a tapered shape.

  The film thickness t3 of the inner wall wiring portion 303 formed in the ink flow path 3a-3 of such a shape is smaller than the film thickness t1 of the electrode portion 301 and the film thickness t2 of the back surface wiring portion 302. It is the same as the form. Although not shown here, the shape of the inner wall of the wiring hole 3b is also similar to the shape of the inner wall of the ink flow path 3a-3.

<Method of Manufacturing Wiring Board 3>
The method of manufacturing the wiring board 3 provided with such an ink flow path 3a-3 is, for example, as follows. First, in the substrate material of wiring board 3, a concave portion of a forward tapered shape is formed from connection surface S3a, and a concave portion of a forward taper shape is also formed from the back surface S3b side according to the formation position of this concave portion. The middle part in the longitudinal direction is communicated. The formation of such a forward-tapered recess is performed, for example, by sand blasting. In addition, you may implement formation of a recessed part first. Thereby, the ink flow path 3a-3 having the tapered inner wall facing the connection surface S3a and the back surface S3b so that the opening diameter becomes smallest at the middle position in the depth direction, and the wiring hole 3b not shown here. Form

  Thereafter, vapor deposition of the wiring material from the connection surface S3a and vapor deposition of the wiring material from the back surface S3b are separately performed. Thereby, the wiring material film is formed on the connection surface S3a and the back surface S3b, and the wiring material film having a thickness smaller than that of the connection surface S3a and the back surface S3b is also formed on the inner wall of the ink flow path 3a-3. . The wiring material film may be formed on the inner wall of the ink flow path 3a separately by vapor deposition of the wiring material separately from the other parts. In this case, vapor deposition is performed from both the connection surface S3a and the back surface S3b. To be. This is similarly applied to the wiring holes 3b whose illustration is omitted here.

  Further, after forming the wiring material film as described above, the wiring material films formed on the connection surface S3a and the back surface S3b are respectively patterned by etching using, for example, a resist pattern as a mask, whereby the wiring 31 is formed. Form.

<Effect of Third Embodiment>
In the ink jet head 103 according to the third embodiment described above, the ink flow path 3a-3 of the wiring substrate 3 has an opening diameter gradually increasing from the middle portion in the depth direction toward the connection surface S3a side and the back surface S3b side Thus, the inner wall is formed in a tapered shape over the entire circumference. As a result, when forming the wiring material film on the inner wall of the ink flow path 3a-3 by vapor deposition, control of the film thickness becomes easy, and the film has a thin film thickness t3 compared to the other parts. The inner wall wiring portion 303 with good thickness stability can be obtained.

  As a result, in addition to the effects of the first embodiment, the film thickness t3 of the inner wall wiring portion 303 can be further reduced, and the long-term reliability of the inkjet head 103 can be further improved. In addition, since variations in volume in the ink flow path 3a can be suppressed more effectively, it is possible to perform image formation with higher accuracy.

Fourth Embodiment
FIG. 12 is an enlarged plan view of the main part of the wiring board in the ink jet head according to the fourth embodiment, and is a view of the wiring board 3 as seen from the connection surface S3a side. FIG. 13 is an enlarged cross-sectional view of the main part of the ink jet head according to the fourth embodiment, and is an AA 'cross section of FIG. 12 and an ink flow provided on the portion B in FIG. It is the figure which expanded one of the path 3a, and its circumference.

  The inkjet head 104 of the fourth embodiment shown in these figures differs from the inkjet head 101 of the first embodiment in the electrodes 31 provided on the wiring substrate 3 and provided on the connection surface S3a of the wiring substrate 3. It is in the configuration of part 301-4. The other configuration is the same as that of the first embodiment including the modification. Therefore, the configuration of the electrode portion 301-4 will be described here.

  The electrode portion 301-4 in the wiring 31 is a portion provided on the connection surface S3a of the wiring substrate 3. The electrode portion 301-4 has a film thickness t1 thicker than the film thickness t3 of the inner wall wiring portion 303, as in the first embodiment, but the film thickness of the portion facing the ink flow path 3a is It has a two-staged film thickness.

  Such an electrode portion 301-4 has a portion patterned in a shape surrounding the ink flow path 3a. Then, the inner diameter of the shape portion surrounding the ink flow path 3a is expanded by one round by thinning the portion facing the ink flow path 3a on the inner peripheral side of the shape portion surrounding the ink flow path 3a. It has a shape. The portion surrounding the wiring hole 3b in the electrode portion 301-4 may have the same configuration, but is not limited to this.

<Method of Manufacturing Wiring Board 3>
FIG. 14 is a manufacturing process diagram of the wiring board of the ink jet head according to the fourth embodiment. Next, according to FIG. 14, a method of manufacturing the wiring board 3 provided with the wiring 31 as described above will be described. In the following, the ink flow path 3a and the wiring hole 3b (not shown) are subjected to the same process, and the ink flow path 3a and the wiring hole 3b are representative of the ink flow path. The steps performed for 3a will be described.

  First, as shown in FIG. 14A, the ink flow path 3 a is formed in the wiring substrate 3. Next, as shown in FIG. 14B, the wiring material film 300 is formed on the connection surface S3a and the back surface S3b of the wiring substrate 3 and the inner wall of the ink flow path 3a. At this time, for example, the wiring material film 300 is formed on the back surface S3b with a thick film thickness t2 by vapor deposition from the back surface S3b side, and the wiring material film 300 is formed on the inner wall of the ink flow path 3a with a small film thickness t3. Membrane. Further, the wiring material film 300 is formed in a thin film thickness on the connection surface S3a by vapor deposition from the connection surface S3a side. In this vapor deposition, the wiring material film 300 is hardly formed on the inner wall of the ink flow path 3a.

  Next, as shown in FIG. 14C, a resist material is formed on the connection surface S3a on which the wiring material film 300 is formed in a state where the ink flow path 3a is embedded, and the resist material film is formed. By performing a lithography process, a resist pattern PR is formed. The resist pattern PR is formed so as to embed the inside of the ink flow path 3a and to cover the periphery of the ink flow path 3a on the connection surface S3a side.

  Thereafter, as shown in FIG. 14D, a wiring material film 300 is additionally formed on the connection surface S3a in a state of covering the resist pattern PR. As a result, the wiring material film 300 on the connection surface S3a has a thick film thickness t1.

  Then, as shown in FIG. 14E, the resist pattern PR is removed to partially remove the wiring material film 300 on the resist pattern PR. As a result, an opening corresponding to the ink flow path 3a is formed in the wiring material film 300 on the connection surface S3a, and this opening has a shape in which the opening diameter is expanded stepwise in the periphery of the ink flow path 3a. Become.

  Thereafter, as shown in FIG. 14F, the wiring material film 300 is patterned on the connection surface S3a and the back surface S3b of the wiring substrate 3 using the resist pattern formed by the lithography process as a mask. Thus, as described above with reference to FIGS. 12 and 13, the wiring 31 having the electrode portion 301-4 is formed.

<Effect of Fourth Embodiment>
In the inkjet head 104 according to the fourth embodiment described above, the electrode portion 301-4 provided on the connection surface S3a of the wiring substrate 3 has a two-stage film thickness in which the film thickness of the portion facing the ink flow path 3a is thin. It is As a result, in the electrode portion 301-4, the thin film thickness portion facing the ink flow path 3a can be used as the storage portion of the conductive adhesive 6 that bonds the wiring substrate 3 and the pressure chamber substrate 2 together. Therefore, while the electrode portion 301-4 provided on the connection surface S3a of the wiring substrate 3 and the individual electrode 21a provided on the connection surface S2a of the pressure chamber substrate 2 are reliably connected by the conductive adhesive 6, the ink It can prevent that the conductive adhesive 6 protrudes inside the communication part of the flow path 3a and the pressure chamber 2a. As a result, it is possible to effectively suppress the variation in the volume of the communicating portion of the ink flow path 3a and the pressure chamber 2a, and it is possible to form an image with higher accuracy.

Reference Signs List 1 nozzle substrate 1a nozzle 2 pressure chamber substrate 2a pressure chamber 21 drive electrode 3 wiring substrate 3a, 3a-3 ink flow path (first through hole)
3b ... Wiring hole (second through hole)
31, 31 '... wiring 31a ... first wiring 31b ... second wiring 301, 301-4 ... electrode part 301a ... lower layer film 301b ... upper layer film 302 ... back surface wiring part 302a ... lower layer film 302b ... upper layer film 303, 303-2 ... Inner wall wiring portion 32 ... Insulating film 4 ... Manifold 4a ... Common ink chamber 100, 101, 101a, 101b, 102, 103, 104 ... Ink jet head 200 ... Image forming device S3a ... Connection surface (wiring board)
S3b ... back side (wiring board)
t1 ... Film thickness of electrode (wiring)
t2 ... Film thickness of back side wiring part (wiring)
t3 ... Film thickness of inner wall wiring section (wiring)
θ 1 ... contact angle (wiring disposed on the inner wall of the first through hole)
θ2 ... Contact angle (wires placed on the back side)

Claims (16)

A nozzle substrate on which a plurality of nozzles are formed;
A pressure chamber substrate in which pressure chambers communicating with the respective nozzles are formed;
A drive electrode provided in the pressure chamber;
A wiring substrate having a first through hole and a second through hole and provided on the pressure chamber substrate on the side opposite to the nozzle substrate;
The wiring substrate is connected to the drive electrode at a connection surface directed to the pressure chamber substrate side, drawn to the back surface to the connection surface via the first through hole, and further via the second through hole. And a wire disposed in a state of being drawn out to the connection surface,
The film thickness of the part arrange | positioned at the inner wall of a said 1st through-hole and a said 2nd through-hole is thinner than the film thickness of the part arrange | positioned on the said connection surface and the said back surface. A manifold having a common ink chamber is provided on the back surface of the wiring substrate,
The first through hole constitutes an ink flow path communicating with the common ink chamber of the manifold and the pressure chamber of the pressure chamber substrate,
The inkjet head according to claim 1, wherein a film thickness of a portion of the wiring disposed on an inner wall of the first through hole is formed thicker on the common ink chamber side than on the pressure chamber substrate side. The first through hole and the second through hole are formed in a forward tapered shape toward the connection surface and the back surface of the wiring substrate such that the opening diameter is smallest at an intermediate position in the depth direction. An ink jet head according to claim 1. A manifold having a common ink chamber is provided on the back surface of the wiring substrate,
The first through hole forms an ink flow path communicating with the common ink chamber of the manifold and the pressure chamber of the pressure chamber substrate, and is disposed at a position where the wiring substrate is bonded to the pressure chamber substrate.
The ink jet head according to any one of claims 1 to 3, wherein a film thickness of a portion of the wiring facing the first through hole on the back surface of the wiring substrate is thinner than a film thickness of another portion. The inkjet according to any one of claims 1 to 4, wherein an insulating film is provided on the back surface of the wiring substrate and the inner wall of the first through hole and the second through hole in a state of covering the wiring. head. The inkjet head according to claim 5, wherein the insulating film is made of a resin. A manifold having a common ink chamber is provided on the back surface of the wiring substrate,
The first through hole constitutes an ink flow path communicating with the common ink chamber of the manifold and the pressure chamber of the pressure chamber substrate,
The contact angle with respect to the ink of the part arrange | positioned at the inner wall of a said 1st through-hole of the said wiring is smaller than the contact angle with respect to the ink of the part arrange | positioned at the said back surface. The inkjet head of description. In the wiring, a constituent material of a portion disposed on an inner wall of the first through hole and the second through hole is different from a constituent material of a portion disposed on the connection surface and the back surface. The inkjet head in any one of -7. The wiring has a laminated structure of a plurality of layers on the connection surface and the back surface of the wiring substrate, and the number of layers smaller than the connection surface and the back surface on the inner wall of the first through hole and the second through hole The ink jet head according to any one of claims 1 to 8, wherein A plurality of pressure chambers of the pressure chamber substrate are provided penetrating through the pressure chamber substrates in a state of being individually communicated with the respective nozzles,
The driving electrode is provided on the inner wall of each pressure chamber in a state of sandwiching a partition between two pressure chambers of the pressure chambers, and constitutes a piezoelectric element.
The ink jet head according to any one of claims 1 to 9, wherein the piezoelectric elements and the pressure chambers are alternately arranged on the pressure chamber substrate. The method of manufacturing an ink jet head according to any one of claims 1 to 10, wherein
Forming the first through hole and the second through hole in the wiring substrate;
Forming a wiring material film on the connection surface of the wiring substrate;
Forming a wiring material film on the back surface of the wiring substrate;
Patterning the wiring material film formed on the connection surface;
Patterning the wiring material film formed on the back surface,
In at least one of the step of forming the wiring material film on the connection surface and the step of forming the wiring material film on the back surface, the inner wall of the first through hole and the inner wall of the second through hole And forming a wiring material film having a film thickness thinner than the wiring material film on the connection surface and the back surface. In the step of forming a wiring material film on the back surface of the wiring substrate,
By forming a wiring material film on the inner wall of the first through hole together with the rear surface by film formation from the rear surface side, the thickness of the rear surface on the inner wall of the first through hole is on the connection surface side The method for manufacturing an ink jet head according to claim 11, wherein the wiring material film is thicker than the film thickness of the film. In the step of forming the first through hole and the second through hole in the wiring substrate,
The first through hole having a forward tapered inner wall directed to the connection surface and the back surface such that the opening diameter becomes smallest at an intermediate position in the depth direction by processing from the connection surface side and the back surface side The method for manufacturing an ink jet head according to claim 11, wherein the second through hole is formed. In both steps of forming a wiring material film on the connection surface of the wiring substrate and forming a wiring material film on the back surface of the wiring substrate, the inner wall of the first through hole and the second penetration The method for manufacturing an ink jet head according to claim 13, wherein the wiring material film is formed on the inner wall of the hole. In the step of forming a wiring material film on the connection surface of the wiring substrate,
Forming a wiring material film on the entire surface of the connection surface of the wiring substrate in which the first through hole and the second through hole are formed;
Then, a resist pattern is formed filling the first through hole from the connection surface side and covering the periphery of the first through hole,
A wiring material film is formed again on the entire surface of the connection surface in a state of covering the resist pattern and the wiring material film,
Thereafter, the resist pattern is removed to selectively remove the portion of the wiring material film covering the resist pattern, whereby the thickness of the portion facing the first through hole is thinner than that of the periphery. The method for manufacturing an ink jet head according to claim 11, wherein the film formation is performed on a connection surface of the wiring substrate. An image forming apparatus comprising the ink jet head according to any one of claims 1 to 10.

Images