JP2009166309A - Inkjet head and method for manufacturing inkjet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet head excellent in assembling accuracy and in assembling easiness, and excellent in adhesiveness of constituent members, and to provide a method for manufacturing the inkjet head. <P>SOLUTION: The inkjet head is characterized in that a connecting electrode 16 for connecting electrically an electrode pulled out of a wall of a pressure room in a substrate 1 of the pressure room having an inlet 141 and an outlet 142 of ink, is formed, and a wiring substrate 3 on which a wiring applying an electric voltage to the connecting electrode 16 is formed is stuck on an end face on the inlet side of the ink of the substrate 1 of the pressure room with an adhesive, and the adhesive is such an adhesive that has both photo-curable properties and heat-curable properties. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet head used for inkjet image recording and a method for manufacturing the inkjet head. More specifically, the inkjet head is improved in assembly accuracy and ease of assembly in an assembly stage of the inkjet head, and excellent in adhesiveness of constituent members. The present invention relates to a head and an ink jet head manufacturing method.

  Liquid ejecting heads that can eject liquid in the form of minute droplets have become widespread, for example, as ink jet heads used in ink jet printers that record images by ejecting ink droplets onto recording paper.

  Such an ink jet head uses a piezoelectric body as a drive element for ejecting liquid, and selectively drives the piezoelectric body corresponding to a plurality of nozzles, so that the liquid from the nozzle is based on the dynamic pressure of each piezoelectric body. It is formed by adhering a plurality of members using an adhesive.

  In addition, an inkjet head that discharges ink in channels arranged in a large number from nozzles is provided with electrodes on a head chip in which channels are formed, and wirings of a wiring board are electrically connected to the electrodes from the drive circuit. The drive signal is applied to the channel via the wiring and electrodes of the wiring board.

  Conventionally, an electrode component such as a head chip and a wiring board are connected by forming an electrode on the head chip and further forming a wiring on the wiring board, and then applying an insulating adhesive between them. They were pressure bonded or connected using an anisotropic conductive film or the like. At this time, each electrode and each wiring are formed by patterning by vapor deposition or etching, or by patterning using a conductive paste and firing.

  Moreover, when electrically connecting an electrode and wiring, it is necessary to ensure conduction | electrical_connection by both contacting reliably. However, the wiring formed by baking the conductive paste after patterning has a slight difference in film thickness for each wiring due to the variation in the degree of shrinkage after baking, which may cause conduction variation between the electrodes. is there. For this reason, normally, when electrically connecting the electrode formed on the electrode component and the wiring formed on the wiring board, a bump is formed in advance on a part of the surface of the wiring, and the electrode and the wiring Is sure to make contact. However, since the electrodes and wiring are in point contact via bumps, in order to ensure the reliability of conduction above a certain level, fine adjustments such as the pressure applied at the time of bonding and the coating thickness of the adhesive are required. It was necessary.

  In particular, in the manufacture of inkjet heads that electrically connect the electrodes formed on the head chip and the wiring of the wiring board, in recent years, the number of channels has become higher and the electrodes and wiring have become increasingly finer. ing. For this reason, it is necessary to pay close attention to ensuring reliable continuity between each electrode and each wiring with high reliability, which has been a factor in increasing manufacturing costs.

  For the above problems, a thermosetting adhesive is used as an adhesive for bonding each constituent member. For example, in the bonding between a wiring board using a thermosetting adhesive and a pressure chamber board, the wiring board is used. Due to the difference in thermal expansion coefficient between the pressure chamber substrate and the pressure chamber substrate, there is a problem that the connection is lost when the adhesive is heat-cured, or the adhesive becomes low viscosity and flows into the flow path during the heating.

  In order to solve the above-mentioned problems when using such a thermosetting adhesive, a bonding method using a photocurable adhesive that cures with light without heating using a photocurable adhesive. It has been known. However, in the bonding method using this photo-curable adhesive, even if the wiring substrate is made transparent and light is irradiated from the substrate side, the adhesive in the shadow of the electrode on the wiring substrate is cured. However, there remain problems such as lowering the adhesive strength when irradiated with light until the solvent resistance is sufficiently high.

  Although it is a problem different from the above, each component is bonded with an adhesive with thermosetting and photo-curing properties, and before it is heat-cured, it is irradiated with light to prevent the adhesive from flowing out. Then, the method etc. which harden | cure the whole by heat processing are proposed.

For example, manufacture of an ink jet head in which a recording element substrate and a support member are fixed by an adhesive composed of an epoxy resin, a silane coupling agent capable of thermally reacting with the epoxy resin, a photo cationic polymerization initiator, and a thermal cationic polymerization initiator A method is disclosed (see Patent Document 1).
However, when these pressure-curing adhesives and photo-curing adhesives are used to bond the pressure chamber substrate and the wiring substrate, especially when the pitch between the electrodes is extremely fine, the heat curing following the photo-curing. Disconnection is likely to occur due to misalignment. Even if there is no problem at the beginning of use of the head, if the use time is prolonged, the electrical connection between the electrode formed on the head chip and the wiring of the wiring board is cut off, and a channel where ink is not ejected is generated.
JP 2007-15238 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an inkjet head excellent in assembly accuracy and ease of assembly, and excellent in adhesiveness of constituent members, and an inkjet head manufacturing method. is there.

  The above object of the present invention is achieved by the following configurations.

  1. A connection electrode for electrically connecting to an electrode drawn out from the pressure chamber wall in the pressure chamber substrate having an ink inlet and an outlet is formed, and a wiring for applying a voltage to the connection electrode is formed. The printed wiring board is bonded to the end face on the ink inlet side of the pressure chamber substrate with an adhesive, and the adhesive is an adhesive having both photocuring property and thermosetting property and containing conductive fine particles. An inkjet head.

  2. 2. The adhesive having both photocuring property and thermosetting property contains an epoxy monomer as a polymerizable monomer and contains a photopolymerization initiator and a thermal polymerization initiator as a polymerization initiator. Inkjet head.

  3. 3. The inkjet head as described in 1 or 2 above, wherein the support of the wiring board is UV transmissive.

  4). An inkjet head manufacturing method for manufacturing the inkjet head according to any one of 1 to 3, wherein a step of applying an adhesive to a surface of the wiring substrate to be bonded to the pressure chamber substrate, and the pressure chamber substrate Determining the position of and bonding to the wiring board; irradiating light from the surface opposite to the adhesive surface of the wiring board; and photocuring the adhesive; and then subjecting the adhesive to heat treatment. A method of manufacturing an ink jet head, wherein the method is manufactured through a step of thermally curing an adhesive.

  5). An inkjet head manufacturing method for manufacturing the inkjet head according to any one of 1 to 3, wherein a step of applying an adhesive to a surface of the wiring substrate to be bonded to the pressure chamber substrate, and the pressure chamber substrate Determining the position of the wiring board and bonding the wiring board to the wiring board; irradiating light from around the bonding surface of the wiring board; and curing the adhesive; and then subjecting the adhesive to heat treatment. A method for producing an ink jet head, comprising: a step of curing.

  According to the present invention, it was possible to provide an inkjet head excellent in assembly accuracy, electrical connectivity, and ease of assembly, and excellent in adhesion of constituent members, and a method for manufacturing the inkjet head.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventor has formed a connection electrode for electrically connecting to an electrode drawn out from a pressure chamber wall in a pressure chamber substrate having an ink inlet and an outlet. In addition, a wiring board on which a wiring for applying a voltage to the connection electrode is formed is adhered to an end face on the ink inlet side of the pressure chamber substrate by an adhesive, and the adhesive is photocurable and thermosetting. As a result of the present invention, the present inventors have found that an ink jet head characterized by being an adhesive having a combination of the above can be realized with an ink jet head excellent in assembly accuracy and ease of assembly and excellent in adhesion of constituent members.

  Hereinafter, the details of the inkjet head of the present invention will be described.

<Inkjet head>
First, a basic configuration example of the ink jet head of the present invention will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view showing an example of the ink jet head of the present invention, and FIG. 2 is a sectional view thereof. 1 and 2, H is an ink jet head, 1 is a pressure chamber substrate (also referred to as a head chip), 2 is a nozzle plate bonded to the front surface of the head chip 1, and 3 is a wiring substrate bonded to the rear surface of the head chip 1. Reference numeral 4 denotes an FPC bonded to the wiring board 3, and reference numeral 5 denotes an ink manifold bonded to the rear surface of the wiring board 3.

  In the present invention, the surface where ink is ejected from the head chip 1 is defined as “front surface”, and the ink inlet side on the opposite surface is defined as “rear surface”. Further, when the head chip 1 is viewed from the front surface or the rear surface, the outer surfaces positioned above and below the channels arranged in parallel are defined as “upper surface” and “lower surface”, respectively.

  In the head chip 1, drive walls 13 and channels 14 made of piezoelectric elements are alternately arranged in parallel. The shape of the channel 14 is such that both side walls rise substantially perpendicular to the upper and lower surfaces and are parallel to each other. As shown in FIG. 2, an outlet 142 and an inlet 141 of each channel 14 are disposed on the front surface and the rear surface of the head chip 1, respectively, and each channel 14 is sized and shaped in the length direction from the inlet 141 to the outlet 142. Is a straight type with almost no change.

  In the head chip 1, each channel 14 has two channel rows in the upper and lower directions in the drawing. Each channel row is composed of six channels 14, but the number of channels 14 constituting the channel row in the head chip 1 is not limited at all.

  The inkjet head of the present invention is provided in a channel (pressure chamber) 14 constituting the head chip 1 in the head chip 1 manufactured by the method described below in the process of manufacturing the inkjet head H shown in FIG. A connection electrode 16 that is drawn from the drive electrode 15 and electrically connected to the drive electrode 15, and a wiring that is provided on the wiring substrate 3 on the inlet 141 side of the pressure chamber 14 and applies a voltage to the connection electrode 16. The electrode 33 is bonded with an adhesive having both photocurability and thermosetting according to the present invention (hereinafter also referred to as a light / thermosetting adhesive).

  In the method of manufacturing the ink jet head of the present invention, the photo / thermosetting adhesive according to the present invention is applied to the surface of the wiring electrode 33 provided on the wiring substrate 3 to be bonded to the drive electrode 15 of the head chip 1. A step of determining the position of the head chip 1, a step of bonding to the wiring substrate 3 having the wiring electrode 33 coated with an adhesive, and a surface of the ink opposite to the bonding surface of the wiring substrate 3. Through the step of irradiating light from the inlet side 141 to photocur the light / thermosetting adhesive according to the present invention, and then performing the heat treatment to thermally cure the light / thermosetting adhesive It is characterized by manufacturing.

  As another method for curing the light / thermosetting adhesive according to the present invention, the light / thermosetting adhesive according to the present invention is photocured by irradiating light from around the bonding surface of the wiring board 3. After that, it is also one of the features that it is manufactured through a process of performing heat treatment and thermosetting.

  A specific method for manufacturing the ink jet head will be further described with reference to FIGS.

  FIG. 3 is an exploded perspective view showing an example of the configuration of the inkjet head.

  The head chip 1 is formed by bonding a piezoelectric body 101 having a plurality of grooves and a lid member 102. Drive electrodes 15 indicated by hatching in FIG. 3 are formed on the surface of the groove of the piezoelectric body 101. The drive electrode 15 is preferably covered with a transparent insulating layer for the purpose of preventing corrosion due to ink.

  On the rear surface of the head chip 1, connection electrodes 16 (voltage application electrodes) drawn from the drive electrodes 15 of the pressure chambers 14 are formed. The connection electrode 16 can be formed by vapor deposition or sputtering.

  The nozzle plate is provided with nozzles 21 at positions corresponding to the outlets of the pressure chambers 14 of the head chip 1, and the front surface of the head chip 1 on which the connection electrodes 16 are formed, for example, Bonding is performed using a thermosetting adhesive. Therefore, the inlet and outlet of each pressure chamber 14 and the nozzle 21 are arranged linearly.

  The wiring board 3 is a plate-like member for connecting a wiring for applying a driving voltage from a driving circuit (not shown) to each driving electrode 15 of the head chip 1. The substrate used for the wiring substrate 3 is a substrate made of a ceramic material such as non-polarized PZT, AlN-BN, or AlN, a substrate made of low thermal expansion plastic or glass, or a piezoelectric material used in the head chip 1. A substrate obtained by depolarizing the same substrate material as the substrate material can be used. Preferably, in order to suppress the occurrence of distortion or the like of the head chip 1 due to the difference in thermal expansion coefficient, a material having a difference in thermal expansion coefficient within ± 3 ppm with respect to unpolarized PZT is selected.

  Furthermore, when the light-transmitting material felt by the photopolymerization initiator is irradiated with light from the side opposite to the adhesive surface of the wiring board, curing of a wide area of the adhesive part proceeds before thermosetting, and the positional displacement of the electrode connection part further increases. It is preferable to be suppressed.

  The substrate constituting the wiring substrate 3 is not limited to a single plate, and a plurality of thin plate materials may be laminated to form a desired thickness.

  The wiring board 3 has a larger area than the rear surface of the head chip 1 and extends in a direction (B direction in the figure) orthogonal to the direction in which the pressure chambers 14 of the head chip 1 are arranged (pressure chamber row direction). Each of the protruding ends is a wiring connecting portion 33 for connecting an FPC (not shown). In addition, the wiring board 3 also protrudes greatly in the direction in which the pressure chambers 14 of the head chip 1 are arranged (A direction in the figure).

  An opening 32 is formed through the substantially central portion of the wiring board 3. The opening 32 is formed in such a size that the inlet side of the total pressure chamber 14 facing the rear surface of the head chip 1 can be exposed.

  As a method for forming the opening 32, depending on the substrate material, a method of processing with a dicing saw, a method of processing with an ultrasonic processing machine, a method of molding and firing ceramics before sintering, a method of forming by sand blasting Etc. can be adopted.

  Wiring electrodes 33 (voltage application electrodes) are formed on the surface of the wiring substrate 3 on the bonding surface side with the head chip 1 with the same number and pitch (W1 + W2) as the connection electrodes 16 formed on the rear surface of the head chip 1. Then, it extends from the peripheral edge of the opening 32 to each wiring connection portion 31, 31 and reaches the outer edge of the wiring board 3. The wiring electrode 33 is electrically connected to each wiring formed in the FPC or the like when the FPC or the like is joined, and the driving voltage from the driving circuit is connected to the driving electrode in the pressure chamber 12 via the connection electrode 14. 15 to function as an electrode for applying to 15.

  In addition to the wiring electrodes 33, a positioning pattern 38 for positioning the head chip 1 is formed on the surface of the wiring substrate 3. The positioning pattern 38 is fitted with a positioning pattern 39 formed on the rear surface of the head chip 1 at the time of joining to the head chip 1 and used when positioning the head chip 1.

  In the present invention, as a method of bonding the head chip 1 and the wiring substrate 3 formed in this way, first, the bonding portion (a part of the wiring electrode 33) of the wiring substrate 3 with the head chip 1 is related to the present invention. Apply light / thermosetting adhesive with a dispenser. Next, the wiring electrode 33 of the wiring board 3 and the connection electrode 16 of the head chip 1 shown in FIG. 4 are electrically connected, and the opening 32 is aligned so that all the channels of the head chip 1 are exposed. Then, the head chip 1 and the wiring board 3 are pressure-bonded.

Next, when the wiring board 3 is light transmissive like glass, a high pressure mercury lamp is irradiated from the periphery of the bonding portion of the wiring board 3 at, for example, 5000 mJ / cm ² illuminance. When the wiring board 3 is made of a light-impermeable material, for example, a high pressure mercury lamp is irradiated from the ink outlet side 142 of the head chip under the irradiation condition of 5000 mJ / cm ² . Further, a high pressure mercury lamp is irradiated around the joint where the head chip 1 and the wiring board 3 are joined. After photocuring by such light irradiation, heat treatment is performed by performing heat treatment at a predetermined temperature and time. In this step, since the constituent members are all fixed by photocuring, heat curing can be performed even if the crimping jig is removed.

  As the irradiation light source used for photocuring of the adhesive, a light source including an ultraviolet lamp that emits ultraviolet light in a specific wavelength region with stable exposure energy and a filter that transmits ultraviolet light of a specific wavelength is preferable. As the ultraviolet lamp, a mercury lamp, a metal halide lamp, an excimer laser, an ultraviolet laser, a cold cathode tube, a hot cathode tube, a black light, an LED (light emitting diode), and the like are applicable, and in particular, a high pressure that emits ultraviolet light having a wavelength of 365 nm. A mercury lamp is preferred.

  Moreover, as a heat processing method, the heating tool which can be heated by crimping | bonding to an electric oven or an inkjet recording head is preferable, for example, a hot plate, a ribbon heater, etc. are mentioned. In addition, as a means for cooling at least the piezoelectric body portion during the heat treatment, it is preferable to use a means for circulating cold water through the aluminum block for cooling.

  Next, a method for forming the wiring electrode 33 of the wiring board 3 will be further described with reference to the drawings.

  FIG. 5 is a plan view of the wiring board 3 showing a state in which the wiring electrodes 33 are patterned on the surface of the wiring board 3 using a conductive paste. For the patterning of the wiring electrode 33 using such a conductive paste, a screen printing method is suitable because it is easy to achieve both fineness and low cost. In addition, patterning using a dispenser or an ink jet can also be employed.

  The conductive paste used in the present invention generally contains a solvent and a thickener in addition to metal particles and a binder resin as a conductive agent. There is no restriction | limiting in particular as a metal particle, Generally Ag can be used, However, Au, Cu, AgPt, AgPtPd etc. can also be used besides.

  In the present invention, the head chip 1 and the wiring board 3 are formed by patterning the wiring electrode 33 on the surface of the wiring board 3 using the conductive paste in this way, and performing a baking process, as shown in FIG. After applying the photo / thermosetting adhesive according to the present invention having conductivity including a small amount of metal particles to the wiring electrode 33a, the connection electrode 16 of the head chip 1 and each wiring electrode 33 are aligned. Then, they are adhered as they are, and then cured by light irradiation treatment and heat treatment. By this curing process, the head chip 1 and the wiring board 3 are simultaneously bonded and bonded.

  When patterning the wiring electrode 33 using a conductive paste, as shown in FIG. 5, the portion 33a of the wiring electrode 33 to be joined to each connection electrode 16 of the head chip 1 is formed narrower than the other portion 33b. It is preferable to do. As a result, when the head chip 1 and the wiring substrate 3 are brought into close contact with each other, even if the portion 33a joined to the connection electrode 16 is crushed and slightly spreads laterally, an electrical short circuit with the adjacent wiring 33 is prevented. be able to.

  7 and 8 are schematic cross-sectional views showing an example of a method for manufacturing the head chip 1.

  As shown in FIG. 7A, first, two piezoelectric element substrates 13a and 13b are bonded to one base substrate 11 using an epoxy adhesive. As the piezoelectric material used for each of the piezoelectric element substrates 13a and 13b, a known piezoelectric material that is deformed by applying a voltage can be used, and lead zirconate titanate (PZT) is particularly preferable. The two piezoelectric element substrates 13a and 13b are laminated so that their polarization directions (indicated by arrows) are opposite to each other, and are bonded to the substrate 11 using an epoxy adhesive.

  Next, as shown in FIG. 7B, a plurality of parallel grooves are ground using a dicing saw or the like over the two piezoelectric element substrates 13a and 13b. Thereby, the drive wall 13 made of a piezoelectric element whose polarization direction is opposite in the height direction is arranged on the base substrate 11 side by side. Each groove is ground at substantially the same constant depth from one end to the other end of the piezoelectric element substrates 13a and 13b, thereby forming a straight channel 14 whose size and shape are not substantially changed in the length direction. .

  Although not shown, instead of using the base substrate 11, the piezoelectric element substrate 13b is thick, and a plurality of parallel grooves extending from the thin piezoelectric element substrate 13a side to the middle of the thick piezoelectric element substrate 13b are ground. By doing so, the portion of the base substrate 11 may be integrally formed by the piezoelectric element substrate 13b simultaneously with the formation of the drive wall 13 whose polarization direction is opposite in the height direction.

  Next, the drive electrode 15 is formed on the inner surface of each channel 14 thus formed. The metal that forms the drive electrode 15 includes Ni, Co, Cu, Al, and the like. Al and Cu are preferably used from the viewpoint of electrical resistance, but Ni is preferably used from the viewpoint of corrosion, strength, and cost. Alternatively, a laminated structure in which Au is further laminated on Al may be employed.

  Examples of the formation of the drive electrode 15 include a method of forming a metal film by a method using a vacuum apparatus such as a vapor deposition method, a sputtering method, a plating method, or a CVD (chemical vapor reaction method). It is particularly preferable to form by electroless plating. By electroless plating, a uniform and pinhole-free metal coating can be formed. The thickness of the plating film is preferably in the range of 0.5 to 5 μm.

  Next, as shown in FIG. 7C, the drive electrode 15 needs to be independent for each channel 14, so that no metal film is formed on the upper end surface of the drive wall 13. For this reason, for example, by sticking a dry film on the upper end surface of each drive wall 13 in advance or forming a resist and forming a metal film, the side walls of each drive wall 13 and each channel 14 are removed. The drive electrode 15 may be selectively formed on the bottom surface.

  Next, as shown in FIG. 7D, after the drive electrode 15 is formed in this way, the cover substrate 12 is bonded to the upper end surface of the drive wall 13 using an epoxy adhesive, and one row of channels is formed. A head substrate 10 having a row is produced. For the base substrate 11 and the cover substrate 12, if the same substrate material as the piezoelectric material constituting the drive wall 13 is depolarized and used, the difference in thermal expansion coefficient due to the effect of heating or driving heat at the time of bonding the substrates is caused. Variations in the speed distribution and drive characteristics due to this can be reduced.

  Further, such a head substrate is not limited to the one manufactured as shown in FIG. 7D, but instead of using the base substrate 11, the piezoelectric element substrate is made thick as shown in FIG. Two sets (upper substrate 10a and lower substrate 10b) are prepared by grinding parallel grooves and alternately arranging drive walls 13 and channels 14 and forming drive electrodes 15 on the inner surface of each channel 14. By adhering this so that the drive walls 13 face each other, a head substrate 10A similar to FIG. In this case, it is not necessary to bond the thin piezoelectric element substrate 13a onto the piezoelectric element substrate 13b as shown in FIG. However, in the following, a case of manufacturing using the head substrate 10 of FIG.

  By using two head substrates 10 produced as shown in FIG. 7 (d), overlaying each other's cover substrates 12 as shown in FIG. 9, and bonding them using an epoxy adhesive, After the laminated head substrate 100 having two channel rows on the upper and lower sides is manufactured, the laminated head substrate 100 is cut along a plurality of cut lines C1, C2,... Along the direction orthogonal to the length direction of the channel 14. By cutting, a plurality of harmonica type head chips 1, 1,... Are produced.

  In the head chips 1, 1... Thus manufactured, drive walls 13 and channels 14 made of piezoelectric elements are alternately arranged in each channel row. The shape of the channel 14 is such that both side walls rise substantially vertically from the base substrate 11 of the head chip 1 and are parallel to each other. An outlet 142 and an inlet 141 of each channel 14 are disposed on the front surface and the rear surface of the head chip 1, respectively. Each channel 14 is a straight type whose size and shape are not substantially changed in the length direction from the inlet to the outlet.

  In such a harmonica type head chip 1, each drive electrode 15 is connected to the drive electrode 15 in each channel 14 in order to connect a wiring such as an FPC for applying a drive voltage from the drive circuit from the outside. It is necessary to pull out to the outer surface of the head chip 1. Therefore, next, on the rear surface of the head chip 1, the connection electrode 16 extends from the portion of the drive electrode 15 formed on the bottom surface of the channel 14 (the surface of the base substrate 11 facing the channel 14) to the rear end surface of the base substrate 11. Pull out to form.

  FIG. 10 is an explanatory diagram for explaining an example of a method of drawing out and forming connection electrodes 16 electrically connected to the drive electrodes 15 on the outer surface of the head chip 1.

  As shown in FIG. 10A, the connection electrode 16 includes at least a portion of the drive electrode 15 formed on the surface of the base substrate 11 facing the channel 14 on the rear surface of the head chip 1. By sticking a photosensitive dry film 200 having an opening 201 opened on the upper surface side and the lower surface side of the substrate, and depositing a metal for electrode formation such as Al to produce a metal film in the opening 201 Can be formed.

  In order to smoothly connect the drive electrode 15 and the connection electrode 16 in the channel 14, it is desirable that the deposition is performed at a predetermined angle, rather than making the rear surface of the head chip 1 perpendicular to the deposition direction. Specifically, it is desirable that the vapor deposition direction (the direction in which the metal particles fly) is not perpendicular to the paper surface of FIG. 10A, but is inclined about 30 to 60 degrees from the vertical to the upper side and the lower side.

  Further, the connection electrode 16 may have a laminated structure by a method such as vapor deposition of Au on a metal film of Al. Further, the connection electrode 16 may be formed by sputtering instead of vapor deposition.

  In particular, when the head chip 1 is cut using the head substrate 10A produced as shown in FIG. 8, there is an adhesive between the drive electrode 15 of the upper substrate 10a and the drive electrode 15 of the lower substrate 10b. So it is not electrically connected. For this reason, when forming a metal film in the opening part 201 of the photosensitive dry film 200, it is necessary to connect these two drive electrodes 15 and 15. FIG. When electrode formation is performed by vapor deposition, this can be realized by performing the vapor deposition direction a plurality of times in a predetermined direction or changing the direction of the substrate during vapor deposition. When forming electrodes by sputtering, metal particles fly from various directions, so that the two drive electrodes 15 and 15 can be connected without changing the direction of the substrate.

  Note that the opening 201 is desirably opened over the entire surface of the channel 14 in consideration of workability in the development process and the water washing process of the photosensitive dry film 200. Opening on the entire surface facilitates removal of the developer and washing water in the channel 14.

  Thereafter, when the photosensitive dry film 200 is removed, as shown in FIG. 10B, the connection electrode 16 electrically connected to the drive electrode 15 from each channel 14 is provided on the rear surface of the head chip 1 for each channel 14. Drawn independently.

  The nozzle plate 2 is provided with nozzles 21 at positions corresponding to the respective channels 14 of the head chip 1, and the light / thermosetting epoxy according to the present invention is formed on the front surface of the head chip 1 on which the connection electrodes 16 are formed. It is preferable to join using a system adhesive.

  The wiring board 3 is a plate-like member for connecting a wiring for applying a driving voltage from a driving circuit (not shown) to the driving electrode 15 of the head chip 1. As a material used for the wiring substrate 3, ceramics such as PZT, AlN-BN, and AlN, glass, and plastic having a low thermal expansion coefficient can be used. A light transmissive material is preferable, and glass is more preferable.

  The wiring substrate 3 has a width equal to or larger than that of the head chip 1 in the direction of alignment of the channels 14 and is orthogonal to the direction of alignment of the channels 14 of the head chip 1 (channel row direction) (FIGS. 1 and 2). In the vertical direction of the head chip 1, and protrudes greatly from the upper surface and the lower surface of the head chip 1, and each protruding end serves as a wiring connection portion 33 for connecting the FPCs 4, 4.

  In addition, an opening 32 is formed through substantially at the center of the wiring board 3. The opening 32 is formed to a size that can expose the inlet 141 side of all the channels 14 of the head chip 1. Therefore, as shown in FIG. 11, with the wiring substrate 3 bonded to the rear surface of the head chip 1, the entire driving wall 13, all the channels 14 and all the driving electrodes 15 of the head chip 1 are viewed through the opening 32. Can be done.

  As a method of forming the opening 32, a method of processing with a dicing saw, a method of processing with an ultrasonic processing machine, a method of molding and firing ceramics before sintering, or sand blasting, depending on the substrate material. A method etc. can be adopted.

  Wiring electrodes 33 are formed at the same number and the same pitch as the connection electrodes 16 formed on the rear surface of the head chip 1 on the surface of the wiring substrate 3 on the bonding surface side with the head chip 1. It extends to. The wiring electrode 33 is electrically connected to each wiring 41 formed on the FPC 4 when the FPC 4 is bonded, and the driving voltage supplied from the driving circuit via the wiring 41 of the FPC 4 is supplied to the connecting electrode 16. It functions as an electrode to be applied to the drive electrode 15 in the channel 14 via.

  The wiring electrode 33 is formed by coating the surface of the wiring substrate 3 with a positive resist by a spin coating method, and then exposing and developing the positive resist using a stripe-shaped mask to develop a stripe-shaped positive resist. It can be performed by exposing the surface of the wiring substrate 3 at the same number and pitch as the connection electrodes 16 and forming a metal film on the surface with a metal for electrode formation by vapor deposition or sputtering. As the metal for forming the electrode, the same metal as the connection electrode 16 can be used.

<< Adhesive with both photocuring and thermosetting >>
The adhesive having both photocurability and thermosetting according to the present invention is not particularly limited, but contains an epoxy monomer as a polymerizable monomer, and contains a photopolymerization initiator and a thermal polymerization initiator as a polymerization initiator. It is preferable to be an adhesive.

(Polymerizable monomer)
In general, examples of the photo / thermopolymerizable monomer include a radical polymerizable monomer and a cationic polymerizable monomer. In the present invention, a cationic polymerizable monomer having high resistance to ink and excellent transferability is preferable. Examples of the cationic polymerization type monomer include various known cationic polymerizable monomers, and examples include compounds having an oxetane ring, epoxy compounds, vinyl ether compounds, etc. Among them, it is preferable to use epoxy monomers. .

  As an epoxy compound applicable to the adhesive according to the present invention, any of a monomer of an epoxy group-containing compound and an oligomer thereof can be used. Specific examples include conventionally known aromatic epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. Hereinafter, the epoxy compound means a monomer or an oligomer thereof.

  A preferable aromatic epoxy compound is a di- or polyglycidyl ether produced by the reaction of a polyhydric phenol having at least one aromatic nucleus or an alkylene oxide adduct thereof and epichlorohydrin, for example, bisphenol A or its Examples thereof include di- or polyglycidyl ethers of alkylene oxide adducts, hydrogenated bisphenol A or di- or polyglycidyl ethers of alkylene oxide adducts thereof, and novolak-type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  As the alicyclic epoxy compound, cyclohexene oxide or cyclopentene obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with an appropriate oxidizing agent such as hydrogen peroxide or peracid. Oxide-containing compounds are preferred, and specific examples include the compounds shown below.

  Preferred examples of the aliphatic epoxy compound include di- or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and typical examples thereof include diglycidyl ether of ethylene glycol and diglycidyl ether of propylene glycol. Or polyglycidyl ether of polyhydric alcohol such as diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, glycerin or alkylene oxide adduct thereof, polyethylene glycol or alkylene oxide thereof Diglycidyl ether, poly (alkylene glycol) such as polypropylene glycol or diglycidyl ether of alkylene oxide adducts thereof Include diglycidyl ether of. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  In addition to these compounds, monoglycidyl ethers of aliphatic higher alcohols and monoglycidyl ethers of phenol and cresol, which are monomers having one oxirane ring in the molecule, can also be used.

  In the present invention, the epoxy monomer is preferably an alicyclic epoxy compound, a bisphenol A type epoxy compound, a bisphenol F type epoxy compound or the like, among which an alicyclic epoxy compound is particularly preferable, and among these, 3,4-epoxy Cyclohexylcarboxylic acid-3 ', 4'-epoxycyclohexylmethyl is preferred because it cures quickly in a low temperature environment. In particular, in a head using a piezoelectric body, the curing temperature is preferably 100 ° C. or lower in order not to cause depolarization. Therefore, an alicyclic epoxy monomer having a high curing rate is preferable.

  These alicyclic epoxy compounds may be produced by any method. For example, Maruzen KK Publishing, 4th Edition Experimental Chemistry Course 20 Organic Synthesis II, 213, 1992, Ed. By Alfred Hasfner, The Chemistry of Heterocyclic Compounds-Small Ring Heterocycles part3, Oxilanes, John & Wiley and Sons, An Interc. 42, 1986, Yoshimura, Adhesion, Vol. 30, No. 7, 42, 1986, Japanese Patent Application Laid-Open No. 11-1000037, Japanese Patent No. 2906245, Japanese Patent No. 2926262, and the like.

(Photopolymerization initiator)
In the present invention, any known photoacid generator can be used as the cationic photopolymerization initiator (photopolymerization initiator) for photopolymerizing the cationic polymerizable monomer. As the photoacid generator, for example, a chemically amplified photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), 187. To page 192).

First, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ salt of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, phosphonium, etc. Secondly, sulfonates that generate sulfonic acid can be mentioned, thirdly, halides that generate hydrogen halide can also be used, and fourthly, iron allene complexes can be mentioned. Examples include hexafluorophosphate, hexafluoroantimonate or pentafluorophenyl borate salt of diallyl iodonium or triallyl sulfonium, Irgacure-261 (manufactured by Ciba Geigy), SP-150, SP-170 (above, Asahi Denka Co., Ltd.) ), PI2074, and UVI-6992 (manufactured by Dow Chemical).

(Thermal polymerization initiator)
In the present invention, the cationic thermal polymerization initiator (photopolymerization initiator) for thermally polymerizing the cationic polymerizable monomer is preferably a compound that generates a cation at a temperature of 10 to 150 ° C. Specific examples include onium salts. Examples of the onium salts include salts of Group Va elements of the periodic table, such as phosphonium salts (for example, triphenylphenacylphosphonium hexafluorophosphate), salts of Group VIa elements, such as sulfonium salts (for example, tetrafluoroborates). Triphenylsulfonium acid, triphenylsulfonium hexafluorophosphate, tris (4-thiomethoxyphenyl) sulfonium hexafluorophosphate, and triphenylsulfonium hexahexafluoroantimonate), salts of Group VIIa elements such as iodonium salts (For example, diphenyliodonium chloride), boron fluoride aniline complex, boron trifluoride monoethylamine complex, trialkylsulfonium antimonate and the like. Among these, an onium salt having an aliphatic hydrocarbon as a substituent is preferable.

  The use of such an aromatic onium salt as a cationic thermal polymerization initiator in the polymerization of an epoxy compound is disclosed in U.S. Pat. Nos. 4,058,401, 4,069,055, and 4,101,513. No. and No. 4,161,478. Further, thermal acid generators such as those described in JP-A No. 2000-10271 and functional materials (May 1995, Vol. 13, No. 5 P. 5 to 11) can also be used.

  Specifically, San-Aid SI-60L (thermal cation generation temperature 90 ° C.), SI-80L (thermal cation generation temperature 110 ° C.), SI-100L (thermal cation generation temperature 120) of San-Aid SI series manufactured by Sanshin Chemical Industry Co., Ltd. ° C), manufactured by Midori Chemical Co., Ltd., NDI105 (thermal cation generation temperature 100 ° C), NB-101 (thermal cation generation temperature 110 ° C), and the like can be used.

  As addition amount of each of these polymerization initiators, it is preferable to add 0.1-30 mass% in solid content of an adhesive agent, More preferably, it is 0.2-10 mass%.

  Examples of the conductive fine particles contained in the adhesive include metal fine particles and non-metallic fine particles coated with metal. Among these, nickel fine particles are preferable in that disconnection hardly occurs.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
An ink jet head having the configuration shown in FIGS. 1, 2, and 3 was produced.

  A conductive paste is formed by screen printing and sintered on the bonding portion of the wiring substrate 3 made of a transparent glass support to the head chip 1 so as to have the structure shown in FIGS. An electrode 33 was formed. The difference between the thermal expansion coefficient of the wiring board and the thermal expansion coefficient of the head chip was 2%. Next, the following adhesive 1 was applied using a dispenser under the condition of a thickness of 5 μm so as to cover the joint portion of the formed wiring board 3 with the head chip.

  Next, the wiring electrode 33 of the wiring board 3 to which the adhesive 1 is applied and the connection electrode 16 of the head chip 1 shown in FIG. 4 are electrically connected, and the openings 32 expose all the channels of the head chip 1. The head chip 1 and the wiring board 3 were pressure-bonded while being aligned as described above.

Next, irradiation was performed for 10 seconds at an illuminance of 2000 mW / cm ² from the wiring substrate 3 toward the ink inlet side 141 using a high-pressure mercury lamp, and then a heat treatment was performed at 100 ° C. for 1 hour. The inkjet head 1 was produced by bonding the wiring substrate 3.

(Composition of adhesive 1)
Celoxide 2021 (alicyclic epoxy resin; manufactured by Daicel UCB) 50 parts Epicoat 807 (bisphenol F type epoxy resin; manufactured by Japan Epoxy Resin)
50 parts Adeka optomer SP-170 (photo cationic polymerization initiator; manufactured by Adeka) 2 parts Adeka Optron CP-77 (thermal cationic polymerization initiator; manufactured by Adeka) 0.4 part A-187 (silane coupling agent; Nippon Unicar) 3 parts Nickel particles (average particle size: 3 μm) 100 parts The inkjet head produced above had no flow of adhesive into the channel. Further, there was no disconnection or short circuit of the electrode.

  As a result of continuous emission for one month using the solvent pigment ink using the ink jet head 1 produced as described above, there was no nozzle shortage, and the adhesion part between the head chip 1 and the wiring board 3 was visually observed. As a result, no peeling of the bonded portion was observed.

Example 2
In the production of the inkjet head 1 described in Example 1, light irradiation for 10 seconds at an illuminance of 2000 mW / cm ² was performed around the joint between the head chip 1 and the wiring board 3 including the ink inlet side 141. Similarly, the inkjet head 2 was manufactured, and the continuous emission for one month was performed using the solvent pigment ink. As a result, there was no nozzle shortage, and the adhesion between the head chip 1 and the wiring board 3 was visually observed. As a result, no peeling of the bonded portion was observed.

Comparative Example 1
In the preparation of the adhesive 1 described in Example 1, the addition amount of Adeka Optron CP-77 (Thermal Cationic Polymerization Initiator; manufactured by Adeka) except for Adekaoptomer SP-170 (Photo Cationic Polymerization Initiator; manufactured by Adeka) Adhesive 2 was prepared in the same manner except that was changed to 2.4 parts.

  In the production of the inkjet head 1 described in Example 1, the inkjet head 3 was produced in the same manner except that the adhesive 2 was used in place of the adhesive 1, but channel clogging due to the adhesive was observed. As a result of continuous emission for one month using the solvent pigment ink, the occurrence of nozzle defects was observed in other channels, and the adhesion portion between the head chip 1 and the wiring board 3 was visually observed. There was a deviation between the wiring connection portion 33 of the wiring board.

Comparative Example 2
In the preparation of the adhesive 1 described in Example 1, except for Adeka Optron CP-77 (thermal cationic polymerization initiator; manufactured by Adeka), an addition amount of Adeka optomer SP-170 (photo cationic polymerization initiator; manufactured by Adeka) Adhesive 3 was prepared in the same manner except that was changed to 2.4 parts.

  In the production of the inkjet head 1 described in Example 1, the inkjet head 4 was produced in the same manner except that the adhesive 3 was used in place of the adhesive 1, and the ink was continuously used for one month using the solvent pigment ink. As a result of the emission, the occurrence of a missing nozzle was observed. As a result of visual observation of the bonded portion between the head chip 1 and the wiring substrate 3, peeling was observed at the bonded portion.

It is a disassembled perspective view which shows an example of the inkjet head of this invention. It is sectional drawing which shows an example of the inkjet head of this invention. It is a disassembled perspective view which shows an example of a structure of an inkjet head. It is a rear view which shows an example of the rear surface of the head chip of the inkjet head of this invention. It is a top view of the wiring board which shows the state which patterned the wiring electrode using the electrically conductive paste on the wiring board surface. It is a top view which shows an example of a mode that an adhesive agent is distribute | arranged to a wiring board. It is a schematic sectional drawing which shows an example of the method of producing a head chip. It is a schematic sectional drawing which shows another example of the method of producing a head chip. It is a figure which shows an example of the method of producing a head chip from one head substrate. It is a schematic sectional drawing which shows an example of the formation method of a connection electrode. It is a rear view which shows an example of the state which joined the wiring board to the head chip.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Head chip 10, 10A Head board 11 Base board 12 Cover board 13 Drive wall 13a, 13b Piezoelectric element board 14 Channel 141 Channel inlet 142 Channel outlet 15 Drive electrode 16 Connection electrode 2 Nozzle plate 21 Nozzle 3 Wiring board 31 Wiring connection Part 32 Opening 33 Wiring electrode 4 FPC
41 Wiring 5 Ink manifold H Inkjet head

Claims (5)

A connection electrode for electrically connecting to an electrode drawn out from the pressure chamber wall in the pressure chamber substrate having an ink inlet and an outlet is formed, and a wiring for applying a voltage to the connection electrode is formed. The printed wiring board is bonded to the end face on the ink inlet side of the pressure chamber substrate with an adhesive, and the adhesive is an adhesive having both photocuring property and thermosetting property and containing conductive fine particles. An inkjet head. The adhesive having both photocurability and thermosetting contains an epoxy monomer as a polymerizable monomer, and contains a photopolymerization initiator and a thermal polymerization initiator as a polymerization initiator. The inkjet head as described. The inkjet head according to claim 1, wherein the support of the wiring board is UV transmissive. An inkjet head manufacturing method for manufacturing the inkjet head according to claim 1, wherein an adhesive is applied to a surface of the wiring substrate to be bonded to the pressure chamber substrate, and the pressure chamber A step of determining the position of the substrate and bonding to the wiring substrate; a step of irradiating light from a surface opposite to the bonding surface of the wiring substrate; A method for producing an ink jet head, comprising: producing the adhesive through a step of thermosetting. An inkjet head manufacturing method for manufacturing the inkjet head according to claim 1, wherein an adhesive is applied to a surface of the wiring substrate to be bonded to the pressure chamber substrate, and the pressure chamber A step of determining the position of the substrate and bonding to the wiring substrate; a step of irradiating light from the periphery of the bonding surface of the wiring substrate to photo-cure the adhesive; and then subjecting the adhesive to heat treatment. A method of manufacturing an ink jet head, wherein the method is manufactured through a thermosetting step.

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