WO2011125886A1

WO2011125886A1 - Inkjet head

Info

Publication number: WO2011125886A1
Application number: PCT/JP2011/058301
Authority: WO
Inventors: 渡辺　英生
Original assignee: コニカミノルタＩｊ株式会社
Priority date: 2010-04-08
Filing date: 2011-03-31
Publication date: 2011-10-13
Also published as: JP2013139083A

Abstract

In the disclosed inkjet head, letting one of a plurality of channel rows furthest to the outside of a head chip be row A and letting the channel row next to row A be row B, a common electrode (15A) connected to drive electrodes (14) in air channels (13) is formed in the channel direction, on a rear surface of the head chip (1), between row A and row B. Furthermore, row-B lead-out electrodes (16B), connected to drive electrodes (14) in row-B ink channels (12), are formed separately and do not contact the common electrode (15A). On the surface where the head chip (1) is joined to a wiring substrate (3), a row-B wiring electrode (36B) that electrically connects to the row-B lead-out electrodes (16B) is formed so as to extend from the area where said row-B wiring electrode (36B) electrically connects to the row-B lead-out electrodes (16B) to an edge of the wiring substrate (3) that extends past the edge of the head chip (1). In a region where the row-B wiring electrode (36B) overlaps the common electrode (15A), at least, the wiring substrate (3) join surface is concave and the row-B wiring electrode (36B) is formed so as to follow said concave surface, preventing the row-B wiring electrode (36B) from contacting the common electrode (15A).

Description

Inkjet head

The present invention relates to an inkjet head, and more specifically, an electrical connection between a drive electrode and a drive circuit of a head chip having a plurality of channel rows in which ink channels that eject ink and air channels that do not eject ink are alternately arranged. The present invention relates to an ink jet head that can be easily connected.

Conventionally, the drive wall is shear-deformed by applying voltage to the drive electrodes formed on both sides of the drive wall that divides the channel, and ink in the channel is ejected from the nozzles using the pressure generated at that time. As a share mode type ink jet head, one having a so-called harmonica type head chip in which an opening of a channel is disposed on each of a front surface and a rear surface is known. In such a share mode type inkjet head, one channel is shared by adjacent channels, and ink cannot be ejected by simultaneously driving adjacent channels. An independent channel type ink jet head is also known in which air channels that do not discharge ink are alternately arranged to enable ink to be discharged simultaneously from adjacent ink channels.

The problem with harmonica-type head chips is how to make electrical connection between the drive electrodes facing each channel and the drive circuit. In order to solve this problem, the present inventor joined a wiring board having a size protruding from the end of the head chip to the rear surface of the head chip, and the end of the wiring board protruding from the end of the head chip. The technique which makes a part a junction part with FPC (flexible printed circuit board) is proposed (patent document 1).

The wiring board has an ink flow path recess having a size covering a channel opened on the rear surface of the head chip, and the surface of the wiring board extends from the outer edge of the ink flow path recess to the end of the wiring board. A wiring electrode is formed over the portion. On the other hand, on the rear surface of the head chip, extraction electrodes that are electrically connected to the drive electrodes in each channel are extracted from each channel to the end of the head chip. By bonding the wiring board to the rear surface of the head chip, each drive electrode can be drawn to the end of the wiring board via the lead electrode and the wiring electrode, thereby facilitating connection with the FPC. Is.

By the way, an inkjet head is required to have a plurality of nozzle rows due to a demand for higher density. For this reason, it is required to produce a head chip having a plurality of channel rows and to electrically connect drive electrodes in each channel of the plurality of channel rows to a drive circuit by FPC. Thus, even in an inkjet head having a plurality of nozzle arrays, by using the above technique, by using a wiring substrate having a wiring electrode corresponding to the leading electrode, the leading electrode is arranged at the end of the rear surface of the head chip. The connection with the FPC can be easily performed at the end of the wiring board.

In particular, in the independent channel type head chip, the ink channel and the air channel are alternately arranged. Therefore, the ink channel of the channel row located inside the two adjacent channel rows is the channel located outside. It is possible to form lead electrodes beyond the air channels in the row to the end of the head chip, and such an ink jet head has already been proposed by the present inventor (Patent Document 2). According to this technique, the drive electrodes of two adjacent channel rows can be drawn out and arranged on the same end side on the rear surface of the head chip, and the same end of the wiring substrate can be obtained by using the wiring substrate. Each electrode corresponding to two channel rows can be drawn out to the part, and if both ends of the wiring board are used, each electrode corresponding to a maximum of four channel rows can be drawn.

At this time, on the rear surface of the head chip, a common electrode (grounding electrode) that is electrically connected to each drive electrode in each air channel has a lead-out direction of the lead-out electrode drawn from each ink channel adjacent to the air channel. Since it is wired in parallel with the channel row on the opposite side, the lead-out electrode drawn out from within each ink channel of the inner channel row is formed up to the end of the head chip so as not to short-circuit with the common electrode of the outer channel row I have to do it. For this reason, in Patent Document 2, a part of the extraction electrode drawn out from each ink channel of the inner channel row is formed on the rear surface of the head chip by a laminate composed of an insulating layer and a metal film layer, and the insulation By wiring so that the layer side is in contact with the common electrode and straddling the common electrode, the lead electrodes of the two channel rows are connected to the same end of the head chip while preventing a short circuit between the lead electrode and the common electrode. Proposes a technique to arrange.

JP 2006-82396 A JP 2008-143167 A

In the method described in Patent Document 2, it is relatively easy to produce a laminate by using a known dry etching technique, but a dry film is attached to the rear surface of the head chip, and unnecessary portions are exposed by exposure and development. In addition to the need to remove the surface, the metal film on the front surface and the lead electrode on the back surface side must be reliably connected, making the production of the laminate complicated and should be solved from the viewpoint of productivity. Has a problem.

In addition, an organic resin film is generally used for the insulating layer forming the laminate, but the durability against strong solvent ink, acid, and alkali ink is not sufficient, and there is a problem to be solved in terms of such durability. Have.

Furthermore, the organic resin film used for the insulating layer generally has a problem that the coefficient of thermal expansion is high and the dimensional change with respect to humidity and tension is large. Especially when the head chip becomes long (50 mm or more), There is also a problem that joining to the rear surface becomes difficult.

Wiring on the back surface of the wiring substrate (opposite to the bonding surface with the head chip) with respect to the drive electrode of the channel row located inside the adjacent two channel rows by the through electrode penetrating the wiring substrate. However, there is a method of drawing out the electrodes to the end of the wiring board by using both the front and back sides of the wiring board (see FIG. 9 of Patent Document 1). However, forming the through electrode on the wiring board is extremely complicated. Therefore, it is not always desirable from the viewpoint of productivity.

Accordingly, the present invention provides an ink jet head having an independent channel type harmonica type head chip having a plurality of channel rows in which ink channels for ejecting ink and air channels for not ejecting ink are alternately arranged. No short circuit with the common electrode occurs without forming a laminated body on the substrate, and it is not necessary to form a through electrode on the wiring board. With a simple structure, each ink channel in two adjacent channel rows It is an object of the present invention to be able to draw out the drive electrode to the same end on the surface of the wiring board.

Other problems of the present invention will become apparent from the following description.

The above problems are solved by the following inventions.

According to the first aspect of the present invention, drive walls made up of channels and piezoelectric elements are alternately arranged side by side, and openings of the channels are arranged on the front surface and the rear surface, respectively, and drive electrodes are formed on the drive walls facing the channels. A head chip in which a plurality of channel rows in which ink channels for discharging ink and air channels for not discharging ink are alternately arranged are arranged in parallel, and the channel rows are arranged on the rear surface of the head chip. A wiring board bonded so as to protrude from the end of the head chip in the installation direction, and a driving signal is transmitted to the driving electrode via a wiring electrode formed on a bonding surface of the wiring board with the head chip. An inkjet head for applying
Of the plurality of channel rows, when any one of the channel rows located on the outermost side of the head chip is A row and the channel row adjacent to the A row is B row, the air is formed on the rear surface of the head chip. A common electrode conducting to the drive electrode in the channel is formed along the channel row direction between the A row and the B row, and for the B row conducting to the drive electrode in the ink channel of the B row The extraction electrode is formed individually without contacting the common electrode,
A B-row wiring electrode that is electrically connected to the B-row lead electrode is connected to the head chip of the wiring board from the electrical connection portion with the B-row lead electrode on the joint surface of the wiring board with the head chip. The joint surface of the wiring board is a concave portion at least in a region where the wiring electrode for the B row and the common electrode overlap with each other. The B-row wiring electrode is formed along the inner surface of the recess, whereby the B-row wiring electrode and the common electrode are not in contact with each other.

In the invention according to claim 2, on the rear surface of the head chip, the A-row lead-out electrodes that are electrically connected to the drive electrodes in the ink channels in the A-row are individually drawn out to the end of the head chip,
An A-row wiring electrode electrically connected to the A-row lead electrode is connected to the head chip of the wiring board from the electrical connection portion with the A-row lead electrode on the bonding surface of the wiring board with the head chip. 2. The ink jet head according to claim 1, wherein the ink jet head is formed over an end portion of the wiring board protruding from the end portion of the wiring board.

The invention according to claim 3 is the ink jet head according to

claim

1 or 2, wherein the concave portion of the wiring board has an inclined surface as a side wall rising from a bottom surface in the concave portion.

According to a fourth aspect of the present invention, the wiring board is individually provided in a portion corresponding to each ink channel of the head chip so that an ink supply port through which ink can be supplied into the ink channel penetrates the front and back sides. 4. The ink jet head according to claim 1, wherein the ink jet head is formed.

5. The ink jet head according to claim 4, wherein the ink supply port is formed in an inclined shape that gradually expands as it goes to a surface opposite to the joint surface with the head chip. It is.

According to a sixth aspect of the present invention, a common ink chamber for storing ink that is commonly supplied to the ink channel is provided on a surface of the wiring board opposite to the joint surface with the head chip. The inkjet head according to

claim

4 or 5.

The invention according to claim 7 is the ink jet head according to any one of claims 1 to 6, wherein the head chip has four channel rows.

According to the present invention, in the inkjet head including the independent channel type harmonica type head chip having a plurality of channel rows in which the ink channels for ejecting ink and the air channels for not ejecting ink are alternately arranged, the rear surface of the head chip No short circuit with the common electrode occurs without forming a laminated body on the substrate, and it is not necessary to form a through electrode on the wiring board. With a simple structure, each ink channel in two adjacent channel rows The drive electrode can be pulled out to the same end on the surface of the wiring board.

The rear view of the head chip in the ink jet head concerning the present invention Plan view of wiring board 1 and 2 (x)-(x) cross-sectional view 1 and 2 (y)-(y) cross-sectional view The figure explaining the manufacture example of a head chip The figure explaining the manufacture example of a head chip The figure explaining the manufacture example of a head chip The figure explaining the manufacture example of a head chip The figure explaining the manufacture example of a head chip The figure explaining the manufacture example of a head chip The figure explaining the manufacture example of a wiring board The figure explaining the manufacture example of a wiring board The figure explaining the manufacture example of a wiring board The figure explaining the manufacture example of a wiring board The figure explaining the manufacture example of a wiring board Partial enlarged view of the recess The figure which shows the other arrangement pattern of a common electrode The figure which shows the other arrangement pattern of a common electrode Plan view showing another example of wiring board

In the head chip according to the present invention, a plurality of channel rows in which ink channels that discharge ink and air channels that do not discharge ink are alternately arranged are arranged in parallel. The head chip has a drive wall made of a piezoelectric element, and channels and drive walls are alternately arranged in parallel, so that both side walls of each channel are constituted by drive walls. The head chip has channel openings on the front and rear surfaces, and drive electrodes are formed on the surfaces of the drive walls facing the channels.

Such a head chip is a so-called harmonica type head chip made of a hexahedron, and by applying a predetermined drive signal to each drive electrode on both sides of the drive wall, the drive wall is deformed into a dogleg shape, A pressure change for ejection is given to the ink supplied to the nozzle, and the ink is ejected as an ink droplet from a nozzle arranged on the front surface of the head chip.

In the present invention, in such a harmonica type head chip, the surface on which the nozzles are arranged and the ink is ejected is defined as “front surface”, and the opposite surface is defined as “rear surface”. Further, the outer surfaces facing each other across the channel row in the head chip are defined as “upper surface” and “lower surface”, respectively.

In such a head chip, when any one of the outermost channel rows among the plurality of channel rows is A row and the channel row adjacent to the A row is B row, it is common to the drive electrodes in the air channel. Is formed along the channel column direction between the A column and the B column.

Here, the common electrode formed between the A row and the B row is electrically connected to at least the driving electrode of the A row air channel of the A row air channel and the B row air channel. I just need it. Therefore, the common electrode may be only the common electrode for the A row that is electrically connected to each of the drive electrodes in the air channel of the A row, or in addition to the common electrode for the A row, the B row A common electrode for the B row that is electrically connected to each of the drive electrodes in the air channel may also be formed between the A row and the B row along the channel row direction. In the former case, the common electrode for the B row that is electrically connected to each of the drive electrodes in the air channel of the B row is formed along the channel row direction on the side opposite to the A row on the rear surface of the head chip. . In the latter case, the common electrode for the A row and the B row may be shared by one common electrode.

On the rear surface of the head chip, B-row lead electrodes that are electrically connected to the drive electrodes in the B-channel ink channels are individually formed. Each lead-out electrode for the B row is electrically connected to the drive electrode facing one of the ink channels in the B row, and extends from there to the channel row side of the A row, and the other end between the A row and the B row. It stops in front of the common electrode without being in contact with the formed common electrode. As a result, the lead electrodes for the B rows are individually arranged between the B rows and the A rows at the same pitch as the B channel ink channels.

On the other hand, the wiring substrate bonded to the rear surface of the head chip is preferably made of a material having a thermal expansion coefficient close to that of the head chip and excellent in dimensional stability. For example, a substrate material such as a glass substrate, a ceramic substrate, or a silicon substrate. Formed by. Its size is such that it projects from the end of the head chip in the direction in which the channel rows are arranged side by side. The overhanging amount is required to have an overhanging amount that can secure at least a connection region with the FPC since the overhanging end portion becomes a connection portion with the FPC. Since the overhang hinders miniaturization, 2-5 mm is appropriate.

On the surface of the wiring substrate (joint surface with the head chip), the B-row wiring electrodes electrically connected to the B-row lead electrodes are arranged at the same pitch as the B-row lead electrodes. To the end of the wiring board protruding from the end of the head chip. The surface of the wiring board is a recess at least in a region where the B-row wiring electrode and the common electrode overlap, and the B-row wiring electrode is formed so as to cross the recess along the inner surface of the recess. Therefore, the B row wiring electrode and the common electrode are configured not to contact each other.

As a result, the drive electrodes in the respective ink channels of the B row are arranged such that the common electrode between the A row and the B row and the channel row of the A row are formed by the B row lead electrode and the B row wiring electrode on the surface of the wiring board. In between, it is pulled out from the end of the head chip on the A row side and extended to the end of the wiring board. For this reason, there is no need to provide a conventional laminate on the rear surface of the head chip, or to provide a through electrode on the wiring board, and there is no short circuit with the common electrode. It is possible to pull out the drive electrode in each ink channel to the same end of the surface of the wiring board.

The concave portion of the wiring board only needs to be formed in a region where at least the B row wiring electrode and the common electrode overlap. Therefore, it can be formed in an arbitrary shape including a region where the B row wiring electrode and the common electrode overlap. For example, the width of the wiring board so as to include a region where the B column wiring electrode and the common electrode overlap. It may be formed in a strip shape having the same width along the direction (the same direction as the channel direction of the head chip channel), or any other shape, or only in the region where the B row wiring electrode and the common electrode overlap. Alternatively, it may be locally formed so as to have the same shape.

When the concave portion is formed in a strip shape so as to include the entire common electrode, the common electrode is accommodated in the concave portion and does not contact the surface of the wiring board, so that the common electrode can be formed thick, thereby The effect of lowering electrical resistance can be obtained. In addition, when an organic insulating protective film (parylene film) for preventing direct contact with water-based ink is formed on the common electrode, even if this organic insulating protective film may expand, There is no interference with the wiring board, and there is no possibility that the wiring board will be lifted.

This recess may be formed to such a depth that the common electrode and the B row wiring electrode along the inner surface of the recess do not come into contact with each other. In addition, it is not necessary to have a depth for forming a space serving as a common ink flow path in each channel. Specifically, it can be 10 to 30 μm. The method of forming the recess is not particularly limited, and in addition to a method of grinding with a dicing saw, in the case of a substrate that can be etched such as a glass substrate or a silicon substrate, it can also be produced by etching. In the case of etching processing, the recess can be formed in an arbitrary shape. In this case, as described above, it is sufficient that a recess is formed at least in a region where the B row wiring electrode and the common electrode overlap.

In addition, the concave portion only needs to have a concave surface on the surface of the wiring board as a result, and the concave portion is not limited to the one formed by digging down from the surface of the wiring substrate. Alternatively, it may be produced by laminating (building up) thin plate-like substrates.

It is preferable that the side wall rising from the bottom surface in the concave portion is an inclined surface. Because of the inclined surface, the angle formed between the side wall and the surface of the wiring board is obtuse at the outer edge of the recess, so that the B-row wiring electrode formed along the inner surface of the recess is the outer edge of the recess. It is possible to avoid the possibility of disconnection at a portion bent along the portion.

In the present invention, the drive electrode in the ink channel of the A column is formed with the A column lead electrode by the same method as the conventional method, and is extended to the end of the wiring substrate by the A column wiring electrode on the surface of the wiring substrate. Can do. In other words, the lead-out electrode for the A column that is electrically connected to the drive electrode in the ink channel of the A column is electrically connected to the drive electrode that faces one of the ink channels in the A column, and is opposite to the channel column side of the B column from there. The head chip extends toward the end of the head chip, and the other end stops at the end on the rear surface of the head chip. As a result, the lead-out electrodes for the A rows are individually arranged at the same pitch as the ink channels in the A row at the end of the rear surface of the head chip. A wiring board in which an A-row wiring electrode electrically connected to the A-row lead electrode protrudes from an end of the head chip on the surface of the wiring board from an electrical connection portion with the A-row lead electrode. It is formed over the end portion.

In the wiring board, ink supply ports that can supply ink into the ink channels may be individually formed in portions corresponding to the ink channels of the head chip so as to penetrate the front and back surfaces. Thereby, ink can be supplied to each ink channel from the back side of the wiring board (the side opposite to the bonding surface with the head chip).

In this case, a common ink chamber for storing ink that is commonly supplied to the ink channels is provided on the surface of the wiring board opposite to the joint surface with the head chip, so that the common ink chamber can be connected via the ink supply port. Ink can be supplied into each ink channel.

The ink supply port is preferably formed in a tapered shape that gradually expands as it goes to the side opposite to the joint surface with the head chip. Thereby, the flow resistance at the time of ink supply from the common ink chamber into each ink channel can be reduced, and smooth ink supply can be realized.

In the case of a head chip having only two channel rows, the present invention uses only one end portion of the wiring substrate that protrudes from one end portion of the head chip, and drives the drive electrodes in the ink channels of each row. Although it can be pulled out, it can also be applied to the case of a head chip having three or more channel rows by utilizing both ends of the wiring board, and in particular, an independent channel type inkjet having four channel rows. An independent channel type ink-jet head that can be easily manufactured with a head, can record images with high density and high definition, and can be easily connected to an FPC can be easily realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 is a rear view of a head chip in an ink jet head according to the present invention, FIG. 2 is a plan view of a wiring board, FIG. 3 is a sectional view taken along line (x)-(x) in FIGS. FIG. 3 is a sectional view taken along line (y)-(y) in FIG.

In the head chip 1, a plurality of channel rows in which drive walls 11 made of piezoelectric elements and

channels

12 or 13 are alternately arranged are arranged in the vertical direction in the figure. Here, each channel row is illustrated as having six channels (three channels 12 and three channels 13), but the number of channels is not limited.

In this head chip 1, the outermost channel row located on the lower side in the figure is the A row, and the inner (upper side) channel row adjacent to the A row channel row is the B row.

It is assumed that the head chip 1 shown in the present embodiment has channel rows arranged in four rows in the vertical direction in the figure, but the head chip 1 having four channel rows is O- Since it has a vertically symmetric shape with the O line as the center, only the two lower channel columns are shown here. Therefore, in the four channel rows, the two outermost channel rows are A rows, and the two innermost channel rows are B rows. In the case of a head chip having only two channel columns, the OO line portion corresponds to the upper end of the head chip.

In each channel row, an ink channel 12 that ejects ink and an air channel 13 that does not eject ink are arranged in parallel every other channel. On the front surface and the rear surface of the head chip 1, the opening

portions

121 and 131 on the front surface side of the

respective channels

12 and 13 and the opening

portions

122 and 132 on the rear surface surface face each other.

Here, in the A row and the B row, the ink channels 12 and the air channels 13 are formed so as to be shifted by one pitch. That is, in FIG. 1, the A-line ink channel 12 and the B-line air channel 13 are arranged on the same vertical line in the figure, and the A-line air channel 13 and the B-line ink channel 12 are on the same vertical line in the figure. It is a relationship to be placed in.

A drive electrode 14 made of a metal film of Ni, Au, Cu, Al, or the like is formed in close contact with the entire inner surface of each channel 12, 13 (including the surface of the drive wall 11 facing the inner surface of the channels 12, 13). ing.

On the rear surface of the head chip 1, one common electrode 15 </ b> A that is electrically connected to the drive electrodes 14 in all the air channels 13 in the A row is arranged in the upper B row in the direction orthogonal to the channel row (the vertical direction in the drawing). Draw out toward the side, and extend between the A row and the B row along the channel row direction (the left-right direction in the drawing). In addition, one common electrode 15B that is electrically connected to the drive electrodes 14 in all the air channels 13 in the B row is formed so as to extend upward in the figure on the opposite side to the A row, and in this portion, the channel row direction (the left and right direction in the drawing) It extends so that.

Further, on the rear surface of the head chip 1, an A-row lead electrode 16A that is electrically connected to the drive electrode 14 in each ink channel 12 of the A row is in a direction opposite to the B-row side, which is the lead-out direction of the common electrode 15A. They are individually drawn out toward the lower end portion 1a in the lower part of the figure, and are arranged in parallel at the same pitch as the ink channels 12 in the A row at the lower end portion 1a.

On the other hand, in each of the ink channels 12 in the B row, a B row lead electrode 16B that is electrically connected to the internal drive electrode 14 is individually directed toward the A row side on the lower side in the figure, which is opposite to the lead direction of the common electrode 15B. A lead-out is formed, extends to the front of the common electrode 15A of the A row, and is parallel to the ink channel 12 of the B row at the same pitch. Each of the B column lead electrodes 16B has a wide end at the common electrode 15A side.

In the openings 132 on the rear surface side of the air channels 13 in the A row and the B row, flow path regulating members 17 that are lid members for preventing the inflow of ink are individually provided, and the openings of the air channels 13 are provided. The part 132 is completely closed. The flow path regulating member 17 is not essential in the present invention, but can be preferably provided in that it can prevent the ink from flowing into the air channel 13 that does not need to eject ink.

As the flow path regulating member 17, it is preferable to use an organic film that can be patterned by general dry etching, and examples thereof include films made of various resins such as polyimide, liquid crystal polymer, aramid, and polyethylene terephthalate. Among these, a polyimide film having good etching properties is preferable. In order to facilitate dry etching, it is desirable to use a film that is as thin as possible, but it is also preferable to use an aramid film that has high strength and can maintain strength even when thin.

Also, a silicon substrate can be used as an insulating layer that can be dry-etched. However, it is necessary to use a special gas such as CF4 or SF6 for dry etching of silicon, and the apparatus becomes special, so that the cost is generally increased.

Furthermore, a method using a photosensitive dry film can also be employed. By sticking the photosensitive dry film to the rear surface of the head chip 1, exposing with a predetermined mask, and developing, the flow path regulating member 17 having a desired shape can be formed.

The nozzle plate 2 is joined to the front surface of the head chip 1. In the nozzle plate 2, nozzles 21 are opened only at positions corresponding to the ink channels 12 in the A row and the B row. Therefore, the opening 131 on the front side of each air channel 13 that does not eject ink is blocked by the nozzle plate 2.

Next, a manufacturing example of the head chip 1 will be described below with reference to FIGS. 5 and 6. However, the present invention is not limited to this.

First, a piezoelectric element substrate 101 made of polarized PZT or the like is bonded onto one substrate 100 using an epoxy adhesive, and a dry film 102 is attached to the surface of the piezoelectric element substrate 101. (FIG. 5 (a)).

Next, a plurality of parallel grooves 103 are ground from the dry film 102 side using a dicing blade or the like. Each groove 103 extends from one end of the piezoelectric element substrate 101 to the other end and is ground at a constant depth almost reaching the substrate 100 so that the size and shape of the groove 103 are almost the same in the length direction. (FIG. 5B).

Next, an electrode forming metal such as Ni, Au, Cu, or Al is applied by sputtering, vapor deposition, or the like from the side on which the groove 103 is ground, and the remaining upper surface of the dry film 102 and the inner surface of each groove 103 are applied. A metal film 104 is formed (FIG. 5C).

Thereafter, by removing the dry film 102 together with the metal film 104 formed on the surface thereof, a substrate 105 having the metal film 104 formed only on the inner surface of each groove 103 is obtained. Then, two similarly formed substrates 105 are prepared, aligned so that the grooves 103 of each substrate 105 match each other, and bonded using an epoxy adhesive or the like (FIG. 5D). .

Next, two head substrates 106 obtained in this way are prepared, overlapped and bonded, and cut along a direction perpendicular to the length direction of the groove 103, thereby providing a plurality of channel arrays having two channel arrays. One harmonica type head chip 1 is formed at a time. Each groove 103 becomes a

channel

12 or 13, the metal film 104 in each groove 103 becomes a drive electrode 14, and a drive wall 11 becomes between adjacent grooves 103. The width between the cut lines C, C... Determines the drive length (L length) of the ink channels 12 of the

head chips

1, 1... Produced thereby, and is appropriately determined according to this drive length. (FIG. 5 (e)).

Next, a dry film 200 as a mask material is formed on the rear surface of the head chip 1 obtained as described above, and

openings

201A and 201B for forming the

common electrodes

15A and 15B and an A column lead electrode 16A are formed. The opening 202A and the opening 202B for forming the B row extraction electrode 16B are formed by exposure and development (FIG. 6).

Then, from the dry film 200 side, for example, Al is applied as an electrode forming metal by vacuum deposition, and an Al film is selectively formed in each of the

openings

201A, 201B, 202A, 202B. With this Al film,

common electrodes

15A and 15B, an A-row lead electrode 16A, and a B-row lead electrode 16B are formed on the rear surface of the head chip 1, respectively.

In order to ensure the connection of the

common electrodes

15A, 15B, the A-row lead electrode 16A and the B-row lead electrode 16B to the drive electrode 14 in each ink channel 12 and the drive electrode 14 in each air channel 13 The vapor deposition is preferably performed twice while changing the direction. Specifically, it is desirable to carry out from a direction perpendicular to the drawing surface and from 30 degrees up and down. Further, as shown in FIG. 5 (d), in order to ensure the connection between the metal films 104 divided vertically, it is also desirable to perform the evaporation from the direction of 30 degrees to the right or left.

Further, the method for forming the Al film is not limited to vapor deposition, and a general thin film forming method can be employed. Moreover, the method of apply | coating an electrically conductive paste with an inkjet can also be used. In particular, the sputtering method is preferable because the direction of the flying metal particles is random, and the metal film can be formed even inside the channel without changing the direction. After the Al film is formed, the dry film 200 is dissolved and peeled off with a solvent to remove the Al film formed on the dry film 200, and the

common electrode

15A, 15B, A row is formed on the rear surface of the head chip 1. The state shown in FIG. 1 is obtained in which only the extraction electrode 16A and the B-row extraction electrode 16B remain.

Note that it is desirable that the dry film 200 be opened on the entire surface of the

channels

12 and 13 in consideration of workability in the development process and the water washing process of the dry film 200. Opening on the entire surface facilitates removal of the developer and washing water in the

channels

12 and 13.

The mask material is not limited to a dry film, and a metal mask may be used.

In the case where the flow path regulating member 17 is provided, a film for a flow path regulating member having a size that covers the entire rear surface of the head chip 1 or each channel row is adhered, and this corresponds to the flow path regulating member 17. After masking the area, the rear surface of the head chip 1 is dry-etched to remove unnecessary films. Specific means for dry etching can be appropriately selected according to the resin used for the flow path regulating member 17. For example, when a polyimide film is used, dry etching can be performed using oxygen plasma.

For etching, wet etching can be used, but generally wet etching is acidic or alkaline, and there is a possibility of damaging the drive electrode 14, so dry etching is preferable. In addition, even if adhesive oozes out when the film is bonded, unnecessary adhesive can be decomposed and removed at the same time when dry etching is performed. The problem of covering up is also solved.

On the other hand, the wiring board 3 has such a size that it protrudes from at least the end portion on the upper surface side and the end portion 1a on the lower surface side of the rear surface of the head chip 1. The surface of the wiring substrate 3 that is a bonding surface with the head chip 1 includes the common electrode 15A so as not to contact the common electrode 15A disposed between the A row and the B row, and the lead for the A row A strip-shaped recess 31 is formed in a portion corresponding to a region not including the electrode 16A and the lead electrode 16B for the B row so as to extend along the channel row direction.

Similarly, on the surface of the wiring board 3, a strip-shaped recess 32 is formed over the region including the

openings

122 and 132 on the rear surface side of each channel of the channel row of the B row so as to follow the channel row of the B row. Is formed. The recess 32 can be produced by the same method as the recess 31. The concave portion 32 is a concave portion for accommodating the flow path regulating member 17 provided in the air channel 13 in the B row, and is not essential in the present invention when the flow path regulating member 17 is not provided.

The surface of the wiring board 3 is formed with the

recesses

31 and 32 as described above, so that the regions of the

recesses

31 and 32 and a planar region having the same height that is relatively convex with respect to the

recesses

31 and 32 are formed. 33, 34, and 35.

In the flat region 33 located on the most end side, A-row wiring electrodes 36A are formed at the same pitch as the A-row lead electrodes 16A formed on the rear surface of the head chip 1. The A-row wiring electrode 36A crosses the planar region 33 from the edge 331 in contact with the recess 31 on the planar region 33 to the lower end 3a of the wiring substrate 3 protruding from the end 1a of the head chip 1. Wired. In the A-row wiring electrode 36A, the vicinity of the edge 331 is an electrical connection portion with the A-row lead electrode 16A.

In addition, the B-row wiring electrodes 36B are formed at the same pitch as the B-row lead electrodes 16B formed on the rear surface of the head chip 1 over the flat area 34, the recess 31 and the flat area 33. The B-row wiring electrode 36B crosses the flat region 34 from a portion close to the edge 341 in contact with the concave portion 32 on the flat region 34, crosses the concave portion 31 along the inner surface of the concave portion 31, and Wiring is performed from the end portion 1a of the head chip 1 to the lower end portion 3a of the wiring substrate 3 so as to cross the plane region 33, and is arranged alternately with the A-row wiring electrodes 36A. In the B-row wiring electrode 36B, a portion on the plane region 34 is an electrical connection portion with the B-row lead electrode 16B.

The B-row wiring electrode 36B is three-dimensionally wired by crossing the concave portion 31 along the inner surface of the concave portion 31, and therefore, at two

edge portions

331 and 342 on the surface side of the concave portion 31 (see FIG. 2). It is formed so as to be bent outwardly. In such a bent portion, there is a concern that disconnection may occur due to the metal film partially thinned. For this reason, as shown in FIG. 8, the side wall 31b rising from the bottom surface 31a of the recess 31 gradually increases as it goes to the surface so that there is no risk of disconnection of the metal film at the

edge portions

331 and 342. By doing so, the angle formed by the side wall 31b and the surface 3b of the wiring board 3 at the

edge portions

331 and 342 is made obtuse. In order to make the side wall 31b an inclined surface, when the recess 31 is dug down, it can be performed by appropriately adjusting processing conditions such as grinding with a dicing saw, sand blasting, and etching. In addition, when building up in a region other than the recess 31, the edge of the substrate to be stacked on the recess side may be tapered in advance.

In the present embodiment, the common wiring electrode 37 is formed on the flat region 35 located in the center so as to correspond to the common electrode 15B formed on the rear surface of the head chip 1. The common wiring electrode 37 is not essential in the present invention, but when the wiring substrate 3 is bonded to the rear surface of the head chip 1, the common wiring electrode 37 is electrically connected to the common electrode 15B, whereby the electric resistance of the common electrode 15B is obtained. It can be preferably provided because of the effect of reducing.

The back surface of the wiring board 3 (the surface opposite to the bonding surface with the head chip 1) has a predetermined depth along the channel row at a position corresponding to each channel row of the A row and the B row of the head chip 1.

Concave grooves

38A and 38B are formed (see FIGS. 3 and 4). The concave groove 38A corresponding to the A row is located on the opposite surface side of the concave portion 31 on the surface of the wiring board 3, and the concave groove 38B corresponding to the B row is the opposite surface side of the concave portion 32 on the surface of the wiring substrate 3. Is located.

These

concave grooves

38A and 38B are not limited to those formed by digging down from the back surface of the wiring board 3 as in the case of the

concave parts

31 and 32. The substrate may be formed by laminating (building up). In the present embodiment, each of the

concave grooves

38A and 38B is formed in an inclined shape that gradually expands toward the back surface side and becomes wider in a direction (vertical direction in the figure) perpendicular to the channel row.

The

concave grooves

38A and 38B do not penetrate the surface of the wiring substrate 3, but ink can be supplied into the ink channels 12 in the A and B rows on the bottom surfaces of the

concave grooves

38A and 38B. Ink supply ports 39 </ b> A and 39 </ b> B are individually formed at positions corresponding to only the ink channels 12. Accordingly, the wiring board 3 penetrates the front and back only at the portions of the

ink supply ports

39A and 39B in the

concave grooves

38A and 38B. The size of each

ink supply port

39A, 39B is at least as large as the opening 122 on the rear surface side of each ink channel 12. Since each

concave groove

38A, 38B is inclined so that the width in the direction orthogonal to the channel row becomes wider toward the back surface side, the flow resistance of the ink supplied from the back surface side of the wiring board 3 is reduced. Ink supply can be performed smoothly.

The

concave grooves

38A and 38B are not limited to being formed in a strip shape along the channel row, and may be formed individually at positions corresponding to only the ink channels 12.

Next, a manufacturing example of such a wiring board 3 will be described below with reference to FIG. 7, but the present invention is not limited to this. FIG. 7 shows a cross section taken along line (x)-(x) in FIG. For this reason, the B row wiring electrode 36B is not shown.

First, a substrate 300 having a predetermined thickness for a wiring board is prepared, and recesses 31 and 32 are formed on the surface to be the surface of the wiring board 3 later (FIG. 7A). Here, a glass substrate having a thickness of 0.7 mm is used as the substrate 300, and the

recesses

31 and 32 each having a depth of 20 μm are ground by a dicing saw. In addition, the

recesses

31 and 32 may be processed by removing the resist only in the portions that become the

recesses

31 and 32 by a resist process, and melting the glass by etching or excavating by sandblasting.

Next, a dry film is formed on the surface of the substrate 300, and after removing the dry film at portions corresponding to the A-row wiring electrode 36A, the B-row wiring electrode 36B, and the common wiring electrode 37 by exposure and development, a vapor deposition method is performed. To form a metal film such as Al having a thickness of 2 μm. Thereafter, the remaining dry film is removed to form the A-row wiring electrode 36A, the B-row wiring electrode 36B, and the common wiring electrode 37 made of a metal film deposited on the surface of the substrate 300 (FIG. 7B). ).

Next,

dry films

401 and 402 are formed on both the front and back surfaces of the substrate 300, and the portions corresponding to the

ink supply ports

39A and 39B of the dry film 401 on the front surface side and the concave grooves of the dry film 402 on the back surface side are exposed and developed. The portions corresponding to 38A and 38B are removed, and then sandblasting is performed from the back surface side of the substrate 300, and the

concave grooves

38A and 38B are spotted at a predetermined depth (FIG. 7C).

Further, sand blasting is also performed from the surface side of the substrate 300, and

ink supply ports

39A and 39B penetrating through the bottom surfaces of the

concave grooves

38A and 38B are individually formed (FIG. 7D).

Finally, the

dry films

401 and 402 are removed to obtain the wiring board 3 (FIG. 7E).

The wiring board 3 manufactured in this way has the surface in contact with the rear surface of the head chip 1, the A column wiring electrode 36A is electrically connected to the A column lead electrode 16A, and the B column wiring electrode 36B. Are aligned so as to be electrically connected to the B-row lead electrode 16B, and are joined by an adhesive, an anisotropic conductive film, or the like. As a result, the drive electrode 14 in each channel 12 of the A column of the head chip 1 is pulled out to the lower end portion 3a of the wiring board 3 via the A column extraction electrode 16A and the A column wiring electrode 36A, and B The drive electrode 14 in each channel 12 of the column is not short-circuited with the common electrode 15A disposed between the A column and the B column via the B column extraction electrode 16B and the B column wiring electrode 36B. Similarly, it is pulled out to the lower end 3a of the wiring board 3 so as to straddle the common electrode 15A. Further, the

ink supply ports

39A and 39B of the wiring board 3 are arranged corresponding to the ink channels 12 of the head chip 1, respectively.

The FPC 4 is connected to the end portions (upper end portion and lower end portion 3a) of the wiring board 3 with respect to the A-row wiring electrode 36A and the B-row wiring electrode 36B exposed therethrough, and the FPC 4 is not connected via the FPC 4. Electrical connection with the illustrated drive circuit is achieved.

A box-shaped manifold 5 is joined to the back surface of the wiring board 3 so as to cover all the

concave grooves

38A and 38B. The inside of the manifold 5 is a common ink chamber 51 in which ink is stored, and the ink in the common ink chamber 51 passes through the

concave grooves

38A and 38B and the

ink supply ports

39A and 39B of the wiring board 3 to each ink channel 12. Supplied in.

FIG. 9 shows another example of the arrangement pattern of the common electrodes formed on the rear surface of the head chip 1. The ink jet head according to the present invention can also be applied to such a common electrode arrangement pattern.

In FIG. 9A, in addition to the common electrode 15A drawn from each air channel 13 in the A row between the A row and the B row, the common electrode 15B drawn from each air channel 13 in the B row is the same. And both are in parallel. In this case, the B-row lead electrode 16B is formed from the corresponding ink channel 12 to the front of the common electrode 15B. In this embodiment, the wiring substrate 3 does not contact any of the

common electrodes

15A and 15B in the region of the recess 31 (the region indicated by the broken line in the figure). Therefore, the B-row wiring formed on the wiring substrate 3 The electrode 36B is not short-circuited with any of these

common electrodes

15A and 15B.

On the other hand, in FIG. 9B, only one common electrode 15 drawn from both of the air channels 13 in the A row and the air channels 13 in the B row is provided between the A row and the B row. And extending in the channel row direction. Also in this case, the B-row lead electrode 16B is formed from the corresponding ink channel 12 to the front of the common electrode 15. Also in this aspect, the wiring board 3 does not contact the common electrode 15 in the region of the recess 31 (the region indicated by the broken line in the figure). Therefore, the B row wiring electrode 36B formed on the wiring substrate 3 is There is no short circuit with the common electrode 15.

In the above embodiment, the air channel 13 is closed by the flow path regulating member 17. However, when such a flow path regulating member 17 is not provided, the air channel 13 is interposed between the depths of the

recesses

31 and 32 and the rear surface of the head chip 1. By appropriately setting the application thickness of the intervening adhesive, the opening 132 on the rear surface side of the air channel 13 can be closed by the adhesive. According to this, the trouble of providing the flow path regulating member 17 is not required, and the ink jet head can be provided with low cost and high reliability. In addition, since no organic film is used, it is possible to inject strong solvent, acid, and alkali inks, thereby widening the range of ink selection.

The

recesses

31 and 32 of the wiring board 3 illustrated above were counterbored by grinding with a dicing saw. On the other hand, according to etching or sandblasting, it is possible to carry out counterbore processing in an arbitrary shape. FIG. 10 shows an example in which the recess 310 is formed by etching in a region where the B-row wiring electrode 36 </ b> B overlaps the common electrode of the head chip 1 on the surface of the wiring substrate 3.

That is, the recess 310 is only in a region where the B row wiring electrode 36B overlaps with the common electrode 15A arranged between the A row and the B row on the rear surface of the head chip 1 as shown in FIGS. Each is formed locally. Accordingly, each recess 310 is individually arranged on the surface of the wiring board 3 so as to correspond to each B row wiring electrode 36B. Each B-row wiring electrode 36B is formed along the inner surface of the corresponding recess 310 so as to traverse the recess 310 in the vertical direction in the figure, so that it does not contact the common electrode 15A and short-circuits each other. There is no.

In the case of the wiring board 3 having such a recess 310, the opening 132 on the rear surface side of the air channel 13 is made of an adhesive for bonding the head chip 1 and the wiring board 3 regardless of the flow path forming member 17. It is easy to close. In this case, a counterbore corresponding to the recess 32 is not necessary.

In the above embodiment, each of the ink channels 12 and the air channels 13 is formed by shifting one pitch in the A row and the B row. This embodiment has an advantage that the B row wiring electrode 36B of the wiring board 3 can be linearly routed over the air channel 13 of the A row as shown in FIG. The pitch of the channel between the B rows is not limited to such a pitch, and may be various pitches.

1: Head chip 1a: Lower end 11: Drive wall 12: Ink channel 121: Front side opening 122: Rear side opening 13: Air channel 131: Front side opening 132: Rear side opening 14:

Drive electrode

15, 15A, 15B: Common electrode 16A: A row extraction electrode 16B: B row extraction electrode 17: Flow path regulating member 2: Nozzle plate 21: Nozzle 3: Wiring board 3a: Lower end 3b: Surface 31 32, 310: Recessed portion 31a: Bottom surface 31b:

Side wall

33, 34, 35: Planar region 36A: A row wiring electrode 36B: B row wiring electrode 37:

Common wiring electrode

38A, 38B:

Concave groove

39A, 39B: Ink supply Mouth 4: FPC
5: Ink manifold 51: Common ink chamber

Claims

Drive walls made up of channels and piezoelectric elements are alternately arranged side by side, and openings of the channels are arranged on the front and rear surfaces, respectively, and drive electrodes are formed on the drive walls facing the channels to discharge ink. A head chip in which a plurality of channel rows in which ink channels and air channels that do not discharge ink are alternately arranged are arranged in parallel, and an end of the head chip in the direction in which the channel rows are arranged on the rear surface of the head chip An inkjet head that applies a drive signal to the drive electrode via a wiring electrode formed on a bonding surface of the wiring substrate to the head chip. ,
Of the plurality of channel rows, when any one of the channel rows located on the outermost side of the head chip is A row and the channel row adjacent to the A row is B row, the air is formed on the rear surface of the head chip. A common electrode conducting to the drive electrode in the channel is formed along the channel row direction between the A row and the B row, and for the B row conducting to the drive electrode in the ink channel of the B row The extraction electrode is formed individually without contacting the common electrode,
A B-row wiring electrode that is electrically connected to the B-row lead electrode is connected to the head chip of the wiring board from the electrical connection portion with the B-row lead electrode on the joint surface of the wiring board with the head chip. The joint surface of the wiring board is a concave portion at least in a region where the wiring electrode for the B row and the common electrode overlap with each other. The B-row wiring electrode is formed along the inner surface of the recess so that the B-row wiring electrode and the common electrode are not in contact with each other.
On the rear surface of the head chip, a row A lead-out electrode electrically connected to the drive electrode in the ink channel of row A is individually drawn out to the end of the head chip,
An A-row wiring electrode electrically connected to the A-row lead electrode is connected to the head chip of the wiring board from the electrical connection portion with the A-row lead electrode on the bonding surface of the wiring board with the head chip. 2. The ink jet head according to claim 1, wherein the ink jet head is formed over an end portion of the wiring board protruding from the end portion of the wiring board.
3. The ink jet head according to claim 1, wherein the concave portion of the wiring board has an inclined surface as a side wall rising from a bottom surface in the concave portion.
The wiring board is individually formed in a portion corresponding to each ink channel of the head chip so that an ink supply port through which ink can be supplied into the ink channel penetrates in the front and back sides. The inkjet head according to claim 1, 2 or 3.
5. The ink jet head according to claim 4, wherein the ink supply port is formed in an inclined shape that gradually expands as it goes to the surface opposite to the joint surface with the head chip.
6. The common ink chamber for storing ink that is commonly supplied to the ink channels is provided on a surface of the wiring board opposite to the joint surface with the head chip. Inkjet head.
The ink-jet head according to any one of claims 1 to 6, wherein the head chip has four channel rows.