JP2013095088A - Inkjet head, manufacturing method thereof, and inkjet plotter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent significant reduction in piezoelectric property, and to prevent film separation or dielectric breakdown of a piezoelectric body 15a even when the piezoelectric body 15a is in continuous operation, thereby achieving high yield and low cost.SOLUTION: A head substrate 10 and a wiring substrate 20 of an inkjet head 1 are bonded with each other via an adhesive resin layer 30. The head substrate 10 includes: pressure chambers 13a configured to store ink; diaphragms 14; and piezoelectric elements 15. The diaphragm 14 is provided to cover the pressure chamber 13a from the side of the wiring substrate 20, and configured to eject the ink stored in the pressure chamber 13a to the outside by vibration. The piezoelectric element 15 is provided on the side of the wiring substrate 20 with reference to the diaphragm 14, and configured to vibrate the diaphragm 14, and includes at least the piezoelectric body 15a located above the pressure chamber 13a. The adhesive resin layer 30 is formed to cover at least the edge of the piezoelectric body 15a, and to include an opening 30a through which a portion of the piezoelectric element 15 is exposed toward the wiring substrate 20 above the pressure chamber 13a.

Description

  The present invention relates to an ink jet head that discharges ink from a pressure chamber, a manufacturing method thereof, and an ink jet drawing apparatus that performs drawing on a recording material using the ink jet head.

  Ink jet heads that eject ink from a plurality of fine nozzles to form images on various recording media are required to have a higher density of nozzles in order to achieve more accurate and finer image formation. ing.

  Ink jet heads are provided with a common ink flow path for each nozzle row, a pressure chamber for applying discharge pressure to the ink, and an individual flow path for supplying ink from the common flow path to the pressure chamber Are individually provided for a plurality of nozzles. Therefore, if these common flow paths, pressure chambers, and individual flow paths are arranged side by side in the nozzle arrangement direction (for example, the horizontal direction), it is difficult to arrange a plurality of nozzles at high density.

  Therefore, conventionally, the inkjet head main body is a laminated body, that is, a nozzle having a pressure chamber provided above the nozzle and a common ink chamber replacing the common flow path above the pressure chamber. Ink jet heads have been proposed in which nozzles are prevented from spreading in the arrangement direction and nozzles can be arranged at high density (see, for example, Patent Document 1). In this ink jet head, the upper wall of each pressure chamber in the laminate is formed into a thin plate to form a vibration plate, and piezoelectric elements are stacked on the upper surface of the vibration plate so as to correspond to the pressure chambers.

  In such an inkjet head having a laminate, it is necessary to form wirings for supplying power to the piezoelectric elements at high density. However, on the substrate (head substrate) on which each piezoelectric element is installed, in addition to the piezoelectric element itself, a flow path for supplying ink to each pressure chamber has already been arranged. There is not enough room.

  For this reason, in Patent Document 1, a wiring substrate (interposer) on which wirings for supplying power to each piezoelectric element is formed is separately formed, and this is stacked on the head substrate from above each piezoelectric element. By electrically connecting the electrodes (upper electrodes) formed on the piezoelectric element and the respective wirings, the wiring density is increased. In addition, a rib partition made of a photosensitive resin is provided between the wiring board and the head board so as to surround the periphery of the piezoelectric element, thereby forming a predetermined space between the wiring board and the piezoelectric element. The wiring board does not hinder the mechanical displacement of the piezoelectric element. In addition, by forming bumps that protrude toward the head substrate side on the wiring on the wiring substrate side, electrical connection between the wiring on the wiring substrate side and the electrodes of the piezoelectric elements on the head substrate side is made via the bumps. I am trying.

  In addition, the piezoelectric element is vulnerable to moisture in the atmosphere and easily deteriorates due to moisture. For this reason, piezoelectric film peeling or dielectric breakdown is likely to occur during continuous driving. In this regard, in Patent Document 1, by forming a low water-permeable insulating film (SiOx) as a protective film on the surface of the piezoelectric element, moisture enters the inside of the piezoelectric element, resulting in poor reliability (PZT film as a piezoelectric body). (Deterioration of piezoelectric characteristics due to reduction of oxygen in the inside) is prevented. Note that SiOx is formed through processes such as film formation by CVD (Chemical Vapor Deposition), patterning by resist hydrofluoric acid etching, and resist removal by oxygen plasma.

JP 2006-264322 A (refer to claim 1, paragraphs [0043], [0060], FIG. 4-1, etc.)

  However, in the configuration of Patent Document 1, since the entire surface of the piezoelectric element is covered with a protective film, the driving of the piezoelectric body located above the pressure chamber is greatly hindered, and the piezoelectric characteristics of the piezoelectric body are greatly deteriorated. In addition, a vacuum process is required for the formation of a protective film by the CVD method and the resist stripping by oxygen plasma. In such a vacuum process, electrons and ions in the chamber are applied to the surface of the piezoelectric element when a voltage is applied. The collision or charging of the surface of the piezoelectric element causes damage to the delicate piezoelectric element, so that the yield decreases. Furthermore, since the protective film is formed through a plurality of steps of film formation, resist patterning, and resist stripping as described above, the manufacturing cost of the entire inkjet head increases.

  Note that the above problem is that, with respect to the substrate on which the piezoelectric element is formed (referred to as the first substrate), another substrate (referred to as the second substrate) is disposed above and the substrates are bonded. This can occur in the same manner as long as the structure is bonded through the resin layer. That is, the second substrate is not a wiring substrate having wiring for supplying power to the piezoelectric element, but for supplying ink from, for example, an ink chamber provided on the second substrate side to the pressure chamber of the first substrate. Even if it is a substrate on which an ink supply path is formed or a simple substrate having no wiring or ink supply path (in this case, the wiring or ink supply path is formed on the first substrate side) Problems can occur.

  The present invention has been made to solve the above-described problems, and its purpose is to protect a part of the piezoelectric element so that the piezoelectric body can be continuously operated while avoiding a significant decrease in piezoelectric characteristics. In this case, the piezoelectric film peeling and dielectric breakdown can be suppressed, and the inkjet head capable of achieving high yield and low cost, the inkjet drawing apparatus including the inkjet head, and the inkjet head It is to provide a manufacturing method.

  In the inkjet head of the present invention, a first substrate and a second substrate for protecting the first substrate are bonded via an adhesive resin layer, and the first substrate receives ink. A pressure chamber to be accommodated, a diaphragm provided so as to cover the pressure chamber from the second substrate side, and discharging ink in the pressure chamber to the outside by vibration; and the second relative to the diaphragm. An inkjet head provided with a piezoelectric element that vibrates the vibration plate, the piezoelectric element having a piezoelectric body positioned at least above the pressure chamber, and the adhesive resin The layer covers at least an edge of the piezoelectric body, and has a portion in which the piezoelectric element is exposed to the second substrate side above the pressure chamber. Yes.

  According to the above configuration, since the adhesive resin layer that bonds the first substrate and the second substrate covers at least the edge of the piezoelectric body, the edge of the piezoelectric body deteriorates by reacting with moisture in the atmosphere. Can be suppressed. Thereby, even when the piezoelectric element is continuously driven so that the ink in the pressure chamber is ejected to the outside by the vibration plate, it is possible to suppress peeling of the piezoelectric body and dielectric breakdown.

  In addition, since the adhesive resin layer has an opening part of the piezoelectric element exposed to the second substrate side above the pressure chamber, the part of the piezoelectric element exposed at the opening is The driving is not hindered by the adhesive resin layer. Thereby, it can suppress that the piezoelectric characteristic of a piezoelectric material falls significantly.

  Furthermore, by adopting a configuration in which the piezoelectric element is protected by using the adhesive resin layer, it becomes possible to protect the piezoelectric element by, for example, heating and curing the adhesive resin layer. A vacuum process for forming a thin film is not necessary. Therefore, after the piezoelectric element is formed, there is no situation in which the delicate piezoelectric element is damaged by the vacuum process, and the manufacturing process is simplified. As a result, it is possible to achieve a high yield and a low cost in manufacturing the inkjet head.

  In the inkjet head according to the aspect of the invention, the first substrate further includes a nozzle serving as an ejection port for ink from the pressure chamber, and includes a plurality of the pressure chambers. It may be provided corresponding to each pressure chamber.

  In this case, in the ink jet head in which each pressure chamber and each nozzle are arranged one-dimensionally or two-dimensionally, the ejection of ink can be controlled by the corresponding piezoelectric body for each pressure chamber.

  In the ink jet head of the present invention, the second substrate may have a wiring for supplying power to the piezoelectric element.

  In this case, since it is not necessary to provide wiring for supplying power to the piezoelectric element on the first substrate, a plurality of pressure chambers are arranged at high density on the first substrate, and corresponding to each pressure chamber. In addition, the piezoelectric body and the nozzle can be arranged with high density. As a result, it is possible to realize an ink jet head that performs high-definition image formation.

  In the ink jet head of the present invention, the second substrate may have an ink supply path serving as a flow path of ink supplied from an ink chamber (which stores ink) to the pressure chamber.

  In this case, since it is not necessary to provide the ink supply path on the first substrate, a plurality of pressure chambers are arranged at high density on the first substrate, and a piezoelectric body and a nozzle are provided corresponding to each pressure chamber. Can be arranged at high density. As a result, it is possible to realize an ink jet head that performs high-definition image formation.

  In the inkjet head of the present invention, the piezoelectric element is located on the second substrate side with respect to the piezoelectric body, a lower electrode located on the opposite side of the second substrate with respect to the piezoelectric body, And an upper electrode formed on the inner side of the formation region of the piezoelectric body, and the adhesive resin layer is provided so as to cover both the edge of the piezoelectric body and the edge of the upper electrode. It is desirable that

  In this configuration, in the region where the upper electrode of the piezoelectric body does not exist, deterioration of the piezoelectric body due to the reaction with the surrounding moisture can be surely suppressed, and between the upper electrode and the lower electrode due to dielectric breakdown of the piezoelectric body. Generation of leakage current can be reliably suppressed.

  In the ink jet head according to the aspect of the invention, it is preferable that the space inside the opening is sealed by the surrounding adhesive resin layer between the first substrate and the second substrate.

  In this case, a gas that does not contain moisture (for example, an inert gas) can be enclosed and confined in the sealed space. Thereby, coupled with the protection of the edge of the piezoelectric body by the adhesive resin layer, the deterioration of the edge of the piezoelectric body due to moisture can be reliably suppressed.

  In the ink jet head of the present invention, it is desirable that the space is filled with an inert gas or dry air.

  Since the inert gas does not contain moisture (water vapor), the piezoelectric body does not deteriorate due to the reaction with the moisture. Further, since the dry air is a remarkably reduced amount of water vapor (water vapor pressure) in the air, it is possible to suppress deterioration of the piezoelectric body due to a reaction with surrounding moisture.

  In the ink jet head of the present invention, the piezoelectric element includes a lower electrode positioned on the opposite side of the piezoelectric substrate from the second substrate, and an upper portion positioned on the second substrate side of the piezoelectric body. The first substrate further includes a first bump that is electrically connected to the upper electrode of the piezoelectric element and protrudes toward the second substrate; The second substrate is electrically connected to the wiring and protrudes toward the first substrate, and further includes a second bump electrically connected to the first bump, It is desirable that the first bump and the second bump are located in a sealed space surrounded by the adhesive resin layer between the first substrate and the second substrate.

  In this case, a gas not containing moisture (for example, an inert gas) can be enclosed and confined in a space where the first bump and the second bump are sealed. As a result, the deterioration of the first bump, the second bump, and the connection portion due to the reaction with moisture can be suppressed, and the piezoelectric body is continuously operated by feeding power from the second substrate to the first substrate. However, it is possible to suppress the occurrence of contact failure at the connection portion between the first bump and the second bump, and to improve the reliability of electrical connection.

  In the ink jet head of the present invention, it is desirable that the space is filled with an inert gas or dry air.

  Since the inert gas does not contain moisture (water vapor), the first bump, the second bump, and the connection portion thereof are not deteriorated by the reaction with the moisture. Further, since the dry air is a remarkably reduced amount of water vapor (water vapor pressure) in the air, it is possible to suppress the deterioration of the connection portion due to the reaction with the surrounding water.

  An ink jet drawing apparatus of the present invention includes the above-described ink jet head of the present invention and a stage on which a recording material is placed, and with respect to the recording material on the stage by ink ejected from the ink jet head. It is characterized by drawing.

  In this case, as an ink jet drawing apparatus that performs drawing on a recording material, an apparatus with high reliability (piezoelectric film peeling and dielectric breakdown hardly occur) can be realized.

  The inkjet head manufacturing method of the present invention includes a pressure chamber for storing ink, a vibration plate for ejecting ink in the pressure chamber to the outside by vibration, and a piezoelectric body positioned at least above the pressure chamber, A bonding step of bonding a first substrate including a piezoelectric element that vibrates the vibration plate and a second substrate for protecting the first substrate through an adhesive resin layer; In the bonding step, the adhesive resin layer covers at least an edge of the piezoelectric body, and a part of the piezoelectric element has an opening exposed to the second substrate above the pressure chamber. After the adhesive resin layer is formed by patterning, the first substrate and the second substrate are bonded via the adhesive resin layer.

  In this case, it is possible to obtain the same effect as that of the above-described configuration of the inkjet head of the present invention.

  In the method for manufacturing an inkjet head of the present invention, in the bonding step, the adhesive resin layer is patterned on the second substrate side, and then the first substrate and the second substrate are bonded to the adhesive resin layer. It is desirable to bond via.

  For example, in the technique of patterning and forming the adhesive resin layer on the first substrate side, there is a high possibility of damaging the piezoelectric element of the first substrate and reducing the piezoelectric characteristics during the patterning. However, the adhesive resin layer is formed by patterning on the second substrate side, and the first substrate and the second substrate are bonded via the adhesive resin layer, so that the piezoelectric element is damaged by the formation of the adhesive resin layer. This can be avoided, and the deterioration of the piezoelectric characteristics due to this can be avoided.

  According to the present invention, the adhesive resin layer that bonds the first substrate and the second substrate is used for protecting the piezoelectric element, thereby protecting the piezoelectric element without using a vacuum process (in a process-saving manner). Realizes an ink jet head with high yield, low cost, high reliability (piezoelectric film peeling and dielectric breakdown less likely to occur during continuous driving), and excellent piezoelectric characteristics of the piezoelectric body can do.

1 is a cross-sectional view illustrating a schematic configuration of an inkjet head according to an embodiment of the present invention. It is sectional drawing which expands and shows the principal part of the said inkjet head. It is a top view of the piezoelectric body and upper electrode in the state without the adhesive resin layer of the said inkjet head. (A) And (b) is sectional drawing which shows the manufacturing process of the said inkjet head. It is a top view which shows an example of the patterning shape of the said adhesive resin layer. It is a top view which shows the other example of the patterning shape of the said adhesive resin layer. It is a perspective view which shows the schematic structure of the inkjet drawing apparatus carrying the said inkjet head.

  An embodiment of the present invention will be described below with reference to the drawings.

(Inkjet head)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an ink jet head 1 according to the present embodiment, and FIG. 2 is a cross-sectional view illustrating an enlarged main part of the ink jet head 1. The inkjet head 1 is formed by bonding a head substrate 10 (first substrate) and a wiring substrate 20 (second substrate) through an adhesive resin layer 30 and integrating them. A box-shaped manifold 40 constituting a common ink chamber 41 in which ink is stored is provided on the upper surface of the wiring board 20.

(About the head substrate)
The head substrate 10 is formed from the lower layer side by a nozzle plate 11 formed of a Si (silicon) substrate, an intermediate plate 12 formed of a glass substrate, and Si of a support layer of an SOI (Silicon on Insulator) substrate. It has a pressure chamber plate 13, a diaphragm 14 formed of Si and SiO _{2 as} an active layer of the SOI substrate, and a piezoelectric element 15. On the lower surface of the nozzle plate 11, a nozzle 11a serving as an ink discharge hole in a pressure chamber 13a described later is opened.

  The pressure chamber plate 13 is formed with a plurality of pressure chambers 13a for containing ink for ejection. The nozzle 11a and the piezoelectric element 15 (particularly, a piezoelectric body 15a described later) are provided corresponding to each of the plurality of pressure chambers 13a. The upper wall of the pressure chamber plate 13 is constituted by the vibration plate 14, and the lower wall is constituted by the intermediate plate 12. The intermediate plate 12 is formed with a communication passage 12a through which the inside of the pressure chamber 13a communicates with the nozzle 11a. The vibration plate 14 is provided so as to cover the pressure chamber 13a from the wiring board 20 side, and causes the ink in the pressure chamber 13a to be discharged to the outside through the nozzle 11a by vibration.

The piezoelectric element 15 is an actuator that is provided on the wiring board 20 side with respect to the diaphragm 14 and vibrates the diaphragm 14. The piezoelectric element 15 is configured by sandwiching a piezoelectric body 15a made of a thin film PZT (Pb (Zr, Ti) O ₃ ) as an actuator body between an upper electrode 15b and a lower electrode 15c. In other words, the piezoelectric element 15 includes a piezoelectric body 15a, a lower electrode 15c located on the opposite side of the wiring board 20 with respect to the piezoelectric body 15a, and an upper electrode 15b located on the wiring board 20 side with respect to the piezoelectric body 15a. Are stacked in this order.

  The lower electrode 15c is formed on the surface of the vibration plate 14, and the piezoelectric body 15a and the upper electrode 15b on the upper surface thereof are individually laminated on the lower electrode 15c so as to correspond to the pressure chamber 13a. Has been. The piezoelectric body 15a is located at least above the pressure chamber 13a (on the wiring board 20 side). In this embodiment, the piezoelectric body 15a extends from above the pressure chamber 13a to above the side wall of the pressure chamber 13a (the pressure chamber 13a and its side wall). It is provided on the lower electrode 15c (so as to straddle the boundary). A gold stud bump 16 (first bump) having a melting point of 1063 ° C. is formed on the upper electrode 15 b so as to protrude toward the wiring substrate 20. The gold stud bump 16 is electrically connected to the upper electrode 15b.

  FIG. 3 is a plan view from the wiring board 20 side of the piezoelectric body 15a and the upper electrode 15b without the adhesive resin layer 30. FIG. As described above, the upper electrode 15b is formed on the piezoelectric body 15a inside the formation area of the piezoelectric body 15a. As a result, the piezoelectric body 15a has a shape in which the periphery (edge) protrudes from the upper electrode 15b. In addition, a region D in the figure shows a region where the piezoelectric element 15 is mainly driven, and the pressure chamber 13a is formed in a shape that is slightly larger than the region D including the formation region of the nozzle 11a. .

(About wiring board)
The wiring board 20 has an upper wiring 23 formed on the upper surface of a substrate body 21 made of a Si substrate via a wiring protective layer 22 made of SiO ₂ . The upper wiring 23 is electrically connected to an FPC (flexible printed circuit board) 25 on which a driving IC 24 is mounted at an end of the wiring board 20 by an ACF (anisotropic conductive film). The upper wiring 23 is covered with a wiring protective layer 26 made of SiO ₂ .

Part of the upper wiring 23, faces the bottom surface of the substrate body 21 via the through hole 21a formed in the substrate main body 21, through the wiring protective layer 22 made of SiO ₂ on the lower surface of the substrate main body 21 The lower wiring 27 formed in this manner is electrically connected. A wiring protective layer 28 made of SiO ₂ is formed on the lower wiring 27, but a part of the lower wiring 27 is exposed through an opening 28 a formed at a position facing the piezoelectric element 15. Yes. Solder bumps 29 (second bumps) that are electrically connected to the lower wiring 27 are formed to protrude toward the head substrate 10 in the lower wiring 27 exposed at the position of the opening 28a. The solder bump 29 and the gold stud bump 16 are electrically connected between the head substrate 10 and the wiring substrate 20.

  The solder bump 29 is made of, for example, Sn—Bi eutectic solder (melting point: 139 ° C.), swells in a hemispherical shape from the surface of the lower wiring 27 toward the piezoelectric element 15, and its front end surface (lower end surface) is spherical. It has become a shape.

  In addition, an ink supply path 21 b is formed in the wiring board 20. The ink supply path 21b is opened on the upper surface of the wiring board 20, and the ink in the common ink chamber 41 can be introduced into the pressure chamber 13a through the opening 26a.

(About adhesive resin layer)
The adhesive resin layer 30 is an adhesive layer for bonding the head substrate 10 and the wiring substrate 20 together. The adhesive resin layer 30 of the present embodiment has a predetermined elastic modulus (for example, 0.1 to 2.5 GPa) in a state before bonding, and is heated to a predetermined curing temperature (for example, 200 ° C.) during bonding. It is a thermosetting adhesive resin layer that exhibits an adhesive function when cured, and is composed of, for example, a thermosetting photosensitive adhesive resin sheet. As such an adhesive resin layer 30, for example, a photosensitive polyimide adhesive sheet manufactured by Toray Industries, Inc., PerMX series (trade name) manufactured by DuPont, or the like can be used.

  The adhesive resin layer 30 is attached in advance to the surface (lower surface) of the wiring protective layer 28 of the wiring substrate 20 in order to ensure a gap corresponding to the thickness of the adhesive resin layer 30 between the head substrate 10 and the wiring substrate 20. Thereafter, it is bonded to the head substrate 10. The adhesive resin layer 30 is patterned into a desired shape by exposure and development after being attached to the wiring substrate 20 and before being laminated with the head substrate 10. The details of the patterning shape of the adhesive resin layer 30 will be described later. By using the above-described photosensitive adhesive resin sheet as the adhesive resin layer 30, unnecessary portions of the adhesive resin layer 30 can be easily removed by exposure and development processes, and a desired pattern layer can be easily formed.

  The adhesive resin layer 30 is previously formed with a through hole 32 penetrating vertically in the same manner by exposure and development. One end (upper end) of the through hole 32 communicates with the ink supply path 21b of the wiring board 20 described above. On the other hand, the other end (lower end) of the through hole 32 has an opening 14 a formed in the vibration plate 14 of the head substrate 10, a through hole 13 b formed in the pressure chamber plate 13, and a communication path formed in the intermediate plate 12. It communicates with the pressure chamber 13a through 12b.

  The adhesive resin layer 30 is required to have moisture resistance for protecting the piezoelectric body 15a from moisture and adhesiveness for reliably bonding the head substrate 10 and the wiring substrate 20. As the moisture-proof and adhesive resin, acrylic resin, urethane resin, epoxy resin, polyimide resin, novolac resin, and the like can be used. Further, as a method for patterning the adhesive resin layer 30 so as to cover the piezoelectric elements 15 arranged at high density, screen printing, letterpress printing, dispenser coating, IJ (inkjet) coating, photolithography method, etc. Can be used.

(About operation)
Since the gold stud bump 16 on the head substrate 10 side and the solder bump 29 on the wiring substrate 20 side are electrically connected, the drive voltage (drive signal) from the drive IC 24 of the wiring substrate 20 is the upper wiring 23, It is supplied to the upper electrode 15b of the piezoelectric element 15 through the lower wiring 27, the solder bump 29, and the gold stud bump 16 in this order. As described above, when a drive voltage is supplied to the upper electrode 15b with respect to the lower electrode 15c of the piezoelectric element 15, the piezoelectric body 15a is deformed by the piezoelectric effect to vibrate the diaphragm 14. Thereby, a pressure for ejection is applied to the ink in the pressure chamber 13a. Then, the ink in the pressure chamber 13a is ejected as fine droplets from the nozzle 11a through the communication path 12a.

  In the present embodiment, the head substrate 10 includes a plurality of pressure chambers 13a, and the piezoelectric body 15a and the nozzle 11a are provided corresponding to each of the pressure chambers 13a. Accordingly, in the inkjet head 1 in which the pressure chambers 13a and the nozzles 11a are arranged one-dimensionally or two-dimensionally, the ejection of ink can be controlled by the corresponding piezoelectric body 15a for each pressure chamber 13a.

  In the present embodiment, the wiring board 20 has wirings (upper wiring 23 and lower wiring 27) for supplying power to the piezoelectric element 15, and an ink supply path 21b. These are not provided on the head substrate 10. Therefore, the plurality of pressure chambers 13a can be arranged with high density on the head substrate 10, and the piezoelectric bodies 15a and the nozzles 11a can be arranged with high density corresponding to each pressure chamber 13a. . As a result, it is possible to realize the inkjet head 1 that performs high-definition image formation. If at least one of the power supply wiring and the ink supply path 21b is provided on the substrate side facing the head substrate 10, the above effect can be obtained.

(Inkjet head manufacturing method)
Next, a method for manufacturing the above-described inkjet head 1 will be described. 4A and 4B are cross-sectional views illustrating the manufacturing process of the inkjet head 1 of the present embodiment. First, as shown in FIG. 4A, after the head substrate 10 and the wiring substrate 20 are separately manufactured, the adhesive resin layer 30 is patterned and formed in a predetermined shape on the wiring substrate 20 side. The patterning shape of the adhesive resin layer 30 will be described later. Thereafter, as shown in FIG. 4B, the head substrate 10 and the wiring substrate 20 are arranged to face each other so that the bonding surface of the adhesive resin layer 30 faces the head substrate 10 side, and the adhesive resin layer 30 is set to a predetermined position. Both substrates are pressure-bonded by heating to the curing temperature. Thereby, the inkjet head 1 in which the head substrate 10, the wiring substrate 20, and the adhesive resin layer 30 are laminated and integrated is completed.

  As described above, in the bonding process between the head substrate 10 and the wiring substrate 20, the adhesive resin layer 30 is patterned and formed in a predetermined shape, and then the head substrate 10 and the wiring substrate 20 are bonded via the bonding resin layer 30. At this time, if the adhesive resin layer 30 is formed by patterning on the head substrate 10 side and bonded to the wiring substrate 20, there is a high possibility of damaging the piezoelectric element 15 of the head substrate 10 during the patterning formation. It becomes a factor which reduces a characteristic. However, as in the present embodiment, after the adhesive resin layer 30 is formed by patterning on the wiring substrate 20 side, the head substrate 10 and the wiring substrate 20 are bonded via the adhesive resin layer 30, so that the adhesive resin layer 30 The piezoelectric element 15 is not damaged at the time of formation, and the deterioration of the piezoelectric characteristics due to the damage of the piezoelectric element 15 can be avoided.

(About patterning shape of adhesive resin layer)
FIG. 5 is a plan view from the side of the wiring board 20 of the piezoelectric body 15a and the upper electrode 15b in a state where the adhesive resin layer 30 is present, and is a plan view illustrating an example of a patterning shape of the adhesive resin layer 30. In FIG. 5, for convenience, a portion covered with the adhesive resin layer 30 is indicated by hatching. Thus, in the present embodiment, the adhesive resin layer 30 is patterned so as to cover at least the edge of the piezoelectric body 15a and to have a shape having the opening 30a and the opening 30b.

  Here, the opening 30a is an opening for exposing a part of the piezoelectric element 15 (for example, the upper electrode 15b) to the wiring substrate 20 side above the pressure chamber 13a. The opening area of the opening 30a corresponds to the area D (the main driving area of the piezoelectric element 15) shown in FIG. The opening 30 b is an opening for forming a space for accommodating the gold stud bump 16 and the solder bump 29. In particular, in the present embodiment, the adhesive resin layer 30 is provided so as to cover both the edge of the piezoelectric body 15a and the edge of the upper electrode 15b. The adhesive resin layer 30 may be provided so as to cover the nozzle 11a, or may be provided so as to be away from the upper side of the nozzle 11a.

  Here, the space S1 (see FIG. 2) inside the opening 30a from which a part of the piezoelectric element 15 is exposed is sealed between the head substrate 10 and the wiring substrate 20 by the surrounding adhesive resin layer 30. . The sealed space S1 is filled with dry nitrogen. In addition, the space S2 (see FIG. 2) inside the opening 30b is also sealed between the head substrate 10 and the wiring substrate 20 by the surrounding adhesive resin layer 30, and the sealed space S2 is included in the sealed space S2. Filled with dry nitrogen. Therefore, the gold stud bump 16 and the solder bump 29 described above are located in a sealed space S2 surrounded by the adhesive resin layer 30. In the manufacture of the ink jet head 1 described above, the bonding process between the wiring substrate 20 on which the adhesive resin layer 30 is formed by patterning and the head substrate 10 is performed in a dry nitrogen atmosphere, whereby the inside of the openings 30a and 30b. The sealed spaces S1 and S2 can be filled with dry nitrogen, respectively.

  Since the adhesive resin layer 30 covers the edge of the piezoelectric body 15a as in this embodiment, it is possible to prevent the edge of the piezoelectric body 15a from reacting with moisture in the atmosphere and deteriorating. As a result, even when the piezoelectric element 15 is continuously driven so that the ink in the pressure chamber 13a is ejected to the outside by the vibration plate 14, film peeling and dielectric breakdown of the piezoelectric body 15a can be suppressed.

  Further, since the adhesive resin layer 30 has an opening 30a where a part of the piezoelectric element 15 is exposed to the wiring board 20 above the pressure chamber 13a, the adhesive resin layer 30 is exposed at the opening 30a of the piezoelectric element 15. The driving of the portion is not hindered by the adhesive resin layer 30. As a result, it is possible to suppress a significant decrease in piezoelectric characteristics as in the conventional case where the entire surface of the piezoelectric element is covered with the protective layer.

  Further, since the piezoelectric element 15 can be protected simultaneously with the adhesion between the head substrate 10 and the wiring substrate 20 by heating and curing the adhesive resin layer 30, a conventional thin film for protecting the piezoelectric element is formed. A separate vacuum process is not required. Therefore, after the piezoelectric element 15 is formed, there is no situation that the delicate piezoelectric element 15 is damaged by the vacuum process, and the manufacturing process is simplified. As a result, in manufacturing the inkjet head 1, a high yield and low cost can be realized.

  That is, by using the adhesive resin layer 30 for protecting the piezoelectric element 15, it is possible to realize a configuration for protecting the piezoelectric element 15 in a process that does not use a vacuum process, and to achieve a high yield and low cost. In addition, it is possible to realize a highly reliable ink jet head 1 with excellent piezoelectric characteristics, which is unlikely to cause film peeling or dielectric breakdown of the piezoelectric body 15a during continuous driving.

  Further, since the adhesive resin layer 30 is provided so as to cover both the edge of the piezoelectric body 15a and the edge of the upper electrode 15b, in the region where the upper electrode 15b does not exist in the piezoelectric body 15a, Deterioration of the piezoelectric body 15a due to reaction can be reliably suppressed. As a result, it is possible to reliably suppress the occurrence of leakage current between the upper electrode 15b and the lower electrode 15c due to the dielectric breakdown of the piezoelectric body 15a.

  Further, since the space S1 inside the opening 30a is sealed by the surrounding adhesive resin layer 30, it can be confined by filling the space S1 with dry nitrogen as in this embodiment. Since dry nitrogen is an inert gas that does not contain moisture, the dry nitrogen does not supply moisture to the piezoelectric body 15a to deteriorate the piezoelectric body 15a. Therefore, coupled with the protection of the edge of the piezoelectric body 15a by the adhesive resin layer 30, it is possible to reliably suppress the deterioration of the edge of the piezoelectric body 15a due to moisture.

  Further, since the gold stud bump 16 and the solder bump 29 are located in the sealed space S2 surrounded by the surrounding adhesive resin layer 30, the dry nitrogen is filled in the space S2 as in this embodiment. And can be trapped. As a result, it is possible to suppress the deterioration due to the reaction of the gold stud bumps 16, the solder bumps 29, and the connection portions thereof with moisture, and even if the piezoelectric body 15 a is continuously operated by feeding power from the wiring substrate 20 to the head substrate 10, It is possible to improve the reliability of electrical connection by suppressing the occurrence of contact failure at the connection portion between the gold stud bump 16 and the solder bump 29.

  In this embodiment, dry nitrogen is used as the inert gas filled in the spaces S1 and S2 of the openings 30a and 30b. For example, a rare gas such as argon, helium, or krypton is used as the inert gas. It may be used. Since nitrogen and rare gas are chemically stable gases that do not react with other substances, the piezoelectric body 15a and the connecting portion between the gold stud bump 16 and the solder bump 29 cause some chemical reaction with the filling gas. It will never deteriorate.

  The spaces S1 and S2 may be filled with dry air instead of the inert gas. The dry air is one in which the amount of water vapor (water vapor pressure) in the air is significantly reduced, and the humidity is reduced to 10% or less, preferably 1% or less. In this way, filling the spaces S1 and S2 with dry air can also suppress the deterioration of the piezoelectric body 15a due to the reaction with the surrounding moisture, and the gold stud bump 16 and the solder bump 29 It can suppress that a connection part deteriorates by reaction with the surrounding water | moisture content.

In addition, said dry air can be obtained with the following methods (1)-(3), for example.
(1) Moist air is cooled to condense, and then heated as necessary to obtain dry air.
(2) Dry air is obtained by bringing wet air into contact with a hygroscopic agent to absorb water vapor.
(3) Dry air is obtained by passing wet air through the hollow fiber membrane to separate water vapor.

  FIG. 6 is a plan view showing another example of the patterning shape of the adhesive resin layer 30. As shown in the figure, the adhesive resin layer 30 is formed by patterning so as to cover the edge of the piezoelectric body 15a and the openings 30a and 30b communicate with each other through the opening 30c inside the region where the piezoelectric body 15a is formed. May be. Even in this case, a part of the piezoelectric element 15 (for example, the upper electrode 15b) is exposed to the wiring substrate 20 side through the opening 30a above the pressure chamber 13a, and the exposed portion of the piezoelectric element 15 is driven. Is not inhibited by the adhesive resin layer 30. Therefore, even in this case, it is possible to suppress a significant decrease in piezoelectric characteristics as compared with the conventional case where the entire surface of the piezoelectric element is covered with a protective layer.

(Substrate facing the head substrate)
In the present embodiment, the configuration in which the head substrate 10 and the wiring substrate 20 are bonded by the adhesive resin layer 30 has been described. However, the substrate bonded to the head substrate 10 may not be a substrate having wiring. That is, as long as it is a substrate for protecting the head substrate 10, for example, it may be a substrate that does not have wiring and has an ink supply path 21 b to the pressure chamber 13 a (in this case, wiring is on the head substrate 10 side). It may be a simple protective substrate having neither wiring nor ink supply path (in this case, wiring and ink supply path are formed on the head substrate 10 side). Even if these substrates are used as the second substrate and bonded to the head substrate 10 as the first substrate via the adhesive resin layer 30, the adhesive resin layer 30 is used as long as the adhesive resin layer 30 is used. Thus, the patterning shape of the present embodiment described above can be applied, and thereby, an effect of suppressing deterioration due to moisture of the piezoelectric body 15a on the head substrate 10 side can be obtained.

(Supplement about the head substrate)
Next, an example of each material constituting the head substrate 10 used in this embodiment will be described. The constituent materials are not limited to the following materials.

  The piezoelectric element 15 sandwiches a piezoelectric body 15a (a thin film PZT formed by sputtering), an upper electrode 15b in which Ti / Au is laminated in this order, and titanium oxide (hereinafter referred to as Ti oxide) / Pt. The lower electrode 15c laminated in order is formed by sputtering, and each is formed by patterning using a photolithographic method. The thickness of each layer is as follows (from the pressure chamber 13a side): Ti oxide: 20 nm, Pt: 100 nm, PZT: 5 μm, Ti: 20 nm, Au: 300 nm.

Ti oxide is a film for improving the adhesion between the underlying SiO ₂ and the upper Pt. The thickness of the Ti oxide is preferably about 5 nm to 40 nm. If it is too thin, the adhesion will be poor, and if it is too thick, the crystallinity of the upper Pt will be poor. Here, Ti oxide is used, but Ti may be used instead of Ti oxide.

  Pt has a role as an electrode for applying a voltage to the piezoelectric body 15a and a role as an orientation control film for improving the crystallinity of PZT constituting the piezoelectric body 15a. If the electrode (Pt) is thick, it is preferable in terms of resistance, but if it is too thick, the smoothness of the surface deteriorates and the crystal state of PZT formed thereon deteriorates. It is preferable that Pt has a <111> orientation with respect to the substrate surface. At this time, PZT tends to have a <100> orientation.

  The thickness of PZT is preferably about 2 μm to 10 μm. If it is too thin, a sufficient amount of displacement cannot be obtained, and if it is too thick, the film tends to be damaged. PZT is preferably in the <100> orientation. In this case, good piezoelectric characteristics are exhibited.

  The upper electrode 15b has a Ti / Au layer structure, and Ti has a role as an adhesive layer for improving the adhesion between Au and PZT. The Au bump (gold stud bump 16) formed on a part of the upper electrode 15b has a role of conducting with the circuit board (wiring board 20).

  In this embodiment, the SOI substrate is used to form the piezoelectric element 15 and perform the processing by the photolithography method. However, the body plate may be formed by processing a silicon wafer. Further, the pressure chamber plate 13 and the intermediate plate 12 and the intermediate plate 12 and the nozzle plate 11 are bonded to each other by anodic bonding because silicon and glass are bonded.

(Inkjet drawing device)
Next, an inkjet drawing apparatus 50 equipped with the inkjet head 1 having the above-described configuration will be described.

  FIG. 7 is a perspective view showing a schematic configuration of the ink jet drawing apparatus 50. The ink jet drawing apparatus 50 includes an ink jet head 1 for performing ink jet drawing and a base 51. On the base 51, a stage 52, a θ rotation mechanism 53, a Y movement mechanism 54, and an X movement mechanism 55 are provided. The X direction and the Y direction are directions orthogonal to each other on the horizontal plane, and the rotation direction in the XY plane is the θ direction. A direction orthogonal to the X direction and the Y direction is taken as a Z direction.

  The stage 52 is a surface plate having a rectangular shape in plan view provided on an X movement mechanism 55 extending in the X direction via a θ rotation mechanism 53, and the upper surface thereof is a horizontal surface on which the recording material W is placed. The mounting surface is disposed such that the mounting surface is at a predetermined height with respect to the nozzle surface of the inkjet head 1. The θ rotation mechanism 53 rotates the stage 52 in the θ direction while maintaining parallel to the nozzle surface of the inkjet head 1. The Y moving mechanism 54 linearly moves the stage 52, the θ rotating mechanism 53, and the X moving mechanism 55 together in the Y direction. The X movement mechanism 55 linearly moves both the stage 52 and the θ rotation mechanism 53 in the X direction.

  The ink jet head 1 is arranged so that its nozzle surface is on the bottom surface of the gantry 56 installed in the X direction near the end on the base 51 via the slider 57, the Z moving mechanism 58 and the θ rotating mechanism 59. Attached and disposed so as to face the surface of the recording material W on the stage 52 disposed below.

  In the above configuration, the inkjet head 1 reciprocates in the X direction when the slider 57 slides along the gantry 56, and moves up and down in the Z direction together with the θ rotation mechanism 59 by the Z moving mechanism 58. Further, the θ rotation mechanism 59 rotates in the θ direction about the Z direction.

  On the other hand, the stage 52 on which the recording material W is placed is linearly moved in the X direction together with the θ rotation mechanism 53 by the X movement mechanism 55. Further, the X moving mechanism 55 linearly moves in the Y direction together with the θ rotating mechanism 53 by the Y moving mechanism 54. Furthermore, the stage 52 is rotationally moved in the θ direction about the Z direction by the θ rotation mechanism 53. As a result, the recording material W on the stage 52 moves in the X and Y directions and rotates in the θ direction.

  In this way, the inkjet head 1 and the stage 52 are relatively moved, and ejection of droplets (ink) from the inkjet head 1 is controlled based on predetermined ejection pattern data according to each position information at that time. Then, desired drawing can be performed on the recording material W by landing on the surface of the recording material W on the stage 52.

  By using the inkjet head 1 as described above, it is possible to realize a highly reliable inkjet drawing apparatus 50 in which piezoelectric film peeling and dielectric breakdown are unlikely to occur.

  The ink jet head of the present invention can be used in an ink jet drawing apparatus.

1 Inkjet head 10 Head substrate (first substrate)
11a Nozzle 13a Pressure chamber 14 Diaphragm 15 Piezoelectric element 15a Piezoelectric body 15b Upper electrode 15c Lower electrode 16 Gold stud bump (first bump)
20 Wiring board (second board)
21b Ink supply path 23 Upper wiring (wiring)
27 Lower wiring (wiring)
29 Solder bump (second bump)
30 Adhesive resin layer 30a Opening 30b Opening 41 Common ink chamber (ink chamber)
50 Inkjet drawing device 52 Stage S1 space S2 space W Recording material

Claims (12)

A first substrate and a second substrate for protecting the first substrate are bonded via an adhesive resin layer;
The first substrate is
A pressure chamber containing ink;
A vibration plate provided so as to cover the pressure chamber from the second substrate side, and for ejecting ink in the pressure chamber to the outside by vibration;
An inkjet head provided on the second substrate side with respect to the diaphragm, and comprising a piezoelectric element that vibrates the diaphragm;
The piezoelectric element has a piezoelectric body positioned at least above the pressure chamber,
The adhesive resin layer covers at least an edge of the piezoelectric body, and is formed to have an opening that exposes a part of the piezoelectric element to the second substrate side above the pressure chamber. An inkjet head characterized by the above. The first substrate further includes a nozzle serving as an ejection port for ink from the pressure chamber, and includes a plurality of the pressure chambers.
The inkjet head according to claim 1, wherein the piezoelectric body and the nozzle are provided corresponding to each pressure chamber.   The inkjet head according to claim 2, wherein the second substrate has wiring for supplying power to the piezoelectric element.   The inkjet head according to claim 2, wherein the second substrate has an ink supply path serving as a flow path for ink supplied from an ink chamber to the pressure chamber. The piezoelectric element is located on a side opposite to the second substrate with respect to the piezoelectric body, and is located on the second substrate side with respect to the piezoelectric body, and the piezoelectric body is formed. An upper electrode formed inside the region,
The inkjet head according to any one of claims 1 to 4, wherein the adhesive resin layer is provided so as to cover both an edge of the piezoelectric body and an edge of the upper electrode.   6. The space inside the opening is sealed between the first substrate and the second substrate by the surrounding adhesive resin layer. 6. The inkjet head as described.   The inkjet head according to claim 6, wherein the space is filled with an inert gas or dry air. The piezoelectric element has a lower electrode located on the opposite side of the piezoelectric body from the second substrate, and an upper electrode located on the second substrate side of the piezoelectric body. ,
The first substrate further includes a first bump that is electrically connected to the upper electrode of the piezoelectric element and protrudes toward the second substrate;
The second substrate further includes a second bump electrically connected to the wiring and protruding toward the first substrate, and electrically connected to the first bump.
The first bump and the second bump are located in a sealed space surrounded by the adhesive resin layer between the first substrate and the second substrate. The inkjet head according to claim 3.   The inkjet head according to claim 8, wherein the space is filled with an inert gas or dry air. An ink jet head according to any one of claims 1 to 9;
A stage on which a recording material is placed,
An ink jet drawing apparatus that performs drawing on the recording material on the stage with ink ejected from the ink jet head. A pressure chamber containing ink, a vibration plate for ejecting ink in the pressure chamber to the outside by vibration, and a piezoelectric element including at least a piezoelectric body located above the pressure chamber and vibrating the vibration plate A first substrate comprising:
An adhesion step of adhering a second substrate for protecting the first substrate via an adhesive resin layer;
In the bonding step, the adhesive resin layer covers at least an edge of the piezoelectric body, and a part of the piezoelectric element has an opening exposed to the second substrate side above the pressure chamber. A method of manufacturing an ink-jet head, comprising: patterning and forming the adhesive resin layer; and bonding the first substrate and the second substrate through the adhesive resin layer.   The bonding step is characterized in that, after the adhesive resin layer is patterned and formed on the second substrate side, the first substrate and the second substrate are bonded via the adhesive resin layer. Item 12. A method for manufacturing an inkjet head according to Item 11.

Images