JP3759713B2 - Electrode connection structure of ink jet head and method of manufacturing ink jet head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode connection structure for connecting an electrode of an inkjet head and an external drive circuit, which enables image formation by pressurizing and discharging ink in an ink chamber onto a recording medium, and a method for manufacturing the inkjet head It is about.
[0002]
[Prior art]
As an inkjet head used in an inkjet printer, an electrode is formed on each inner surface of a pair of partition walls sandwiching a grooved ink chamber, and the partition walls are deformed by applying a drive pulse from an external drive circuit to the electrodes. Some of them eject ink in the ink chamber. In such an ink jet head, an electrode formed in the ink chamber is extended outside the ink chamber to form an outdoor electrode for extraction, and the outdoor electrode and an external drive circuit including a driving IC (Integrated Circuit) are electrically connected. To make connections. As a method for connecting an outdoor electrode and an external drive circuit in a conventional inkjet head, as shown in FIGS. 14 to 16, a method using a bonding wire, a method using a TAB (Tape Automated Bonding) lead, and a method using a flexible substrate It has been known.
[0003]
That is, the actuator 100 is disposed on the support 110 together with the driving IC 130. The actuator 100 includes a substrate 103, a cover plate 123, a nozzle plate 125, and an ink chamber electrode 101. The substrate 103 is made of a piezoelectric element, has a plurality of partition walls 127 arranged in a direction perpendicular to the drawing, and has an ink chamber 122 between each partition wall 127. The cover plate 123 has a supply port 124 for supplying ink to each ink chamber 122 and is disposed on the upper surface of the substrate 103. The nozzle plate 125 includes nozzles 126 that eject ink from the ink chambers 122 and is disposed on the front surface of the substrate 103. The ink chamber electrode 101 is formed in a substantially half range on the upper side of the partition wall 127 in each ink chamber 122. The ink chamber electrode 101 is formed so as to extend to the back side of the upper surface of the substrate 103, and the extended portion constitutes an ink chamber electrode 102 for extraction.
[0004]
In the method using the bonding wire, as shown in FIG. 14, the ink outdoor electrode 102 of the actuator 100 and the connection point of the driving IC 130 are electrically connected by the bonding wire 111. The bonding wire 111 is connected from above by using an Al (aluminum) wedge wire bonding technique or an Au (gold) wire bonding technique with respect to the upper surface of the ink outdoor electrode 102 which is a flat surface and the connection point of the driving IC 130. In this state, heating ultrasonic waves are applied in a state where the bonding wire 111 is pressed via metal solid phase diffusion bonding.
[0005]
In the method using the TAB lead, the outer lead 112 of the TAB device is electrically connected to the ink outdoor electrode 102 of the actuator 100 as shown in FIG. In this connection, the outer lead 112 of the TAB device is positioned in parallel with the ink outdoor electrode 102 of the actuator 100, and a lead pressing tool having a heating and pressing mechanism is pressed from above, and the lower surface of the outer lead 112 is pre-plated. It is performed by melting the solder that is present and soldering. Instead of solder, ACF (anisotropic conductive film) or ACP (anisotropic conductive paste) may be used.
[0006]
In the method using the flexible substrate, as shown in FIG. 16, the connection electrode 115 formed on the printed circuit board 114 on which the driving IC 130 is mounted and the ink outdoor electrode 102 of the actuator 100 are electrically connected by the flexible substrate 113. Is done. For this connection, both ends of the flexible substrate 113 are placed on the upper surfaces of the connection electrode 115 and the ink outdoor electrode 102, and solder bonding, ACF or ACP is performed as in the case of using the TAB lead shown in FIG. Is done.
[0007]
Next, a conventional manufacturing method of the actuator constituting the ink jet head will be described with reference to FIG.
[0008]
First, a dry film resist is laminated and cured on the upper surface 103a of the substrate 103 made of a piezoelectric element polarized in the thickness direction (vertical direction in the figure). Thereafter, the upper surface 103a is half-diced from the front surface 103b side to the back surface 103c side using a dicer dicing blade to form an ink chamber 122 sandwiched between the partition walls 127. At this time, the dicing blade is raised at the intermediate portion between the front surface 103b and the back surface 103c of the substrate 103 to form a rounded portion 122a on the back surface side of the ink chamber 122, and only the dry film resist on the top surface 103a is cut to the back surface 103c. Thus, the flat portion 122b is formed.
[0009]
This dicing process is repeatedly performed in a direction parallel to the front surface 103 b and the back surface 103 c of the substrate 103 to form an ink chamber array on the substrate 103. Thereafter, a metal serving as an electrode material such as Al or Cu (copper) is obliquely deposited from above the substrate 103 in the longitudinal direction of the ink chamber 122. By performing this operation from two directions (indicated by arrows in the figure) facing each other across the ink chamber 122, the ink chamber electrodes 101 are formed on the partition walls 127 on both sides of the ink chamber 122.
[0010]
At this time, in the ink chamber 122, the electrode 101 is formed in a range from the upper surface 103 a of the partition wall 127 to about ½ in the thickness direction of the partition wall 127 due to the shadowing effect of the dry film resist and the partition wall 127. In addition, oblique deposition of the electrode material is simultaneously performed on the rounded portion 122a and the flat portion 122b of the ink chamber 122. At this time, the thickness and opening width of the dry film resist are set so that the metal films deposited from the left and right directions overlap at the flat portion 122b. Thereby, in the flat part 122b, the electrode (ink outdoor electrode) 102 is formed on the entire surface of the opening. In the rounded portion 122a, an electrode is formed so as to connect the ink chamber electrode 101 in the ink chamber 122 and the ink chamber outer electrode 102 in the flat portion 122b.
[0011]
Thereafter, the cover plate 123 having the supply port 124 is bonded to the upper surface 103a of the substrate 103 as shown in FIGS. 14 to 16, and the nozzle plate 125 having the nozzle 126 is bonded to the front surface 103b of the substrate 103. The actuator 100 is completed.
[0012]
The actuator 100 formed in this way performs share mode driving by applying potentials of opposite phases to the ink chamber electrodes 101 formed in the ink chambers 122 adjacent to each other with the partition wall 127 interposed therebetween. That is, the partition wall 127 to which opposite polarities are applied to both side surfaces undergoes shear deformation in the shape of “<” or “<” in the boundary between the formation region and the non-formation region of the ink chamber electrode 101. Arise. The volume of the ink chamber 122 changes due to the shear deformation of the partition wall 127, and the ink pressure in the ink chamber 122 changes accordingly, and ink droplets are ejected from the nozzle 126 arranged on the front surface 103b side of the ink chamber 122. The
[0013]
[Problems to be solved by the invention]
However, in the conventional inkjet head configured as described above, the active region that directly contributes to ink ejection in the ink chamber 122 formed in the actuator 100 is the range on the front surface 103b side (nozzle formation side) from the supply port 124. Only. The back surface 103 c side including the supply port 124 is an area for supplying ink into the ink chamber 122, and the round portion 122 a and the flat portion 122 b connect the ink chamber electrodes 101 facing each other in the ink chamber 122 to form one ink. The outdoor electrode 102 is an area for electrically connecting the ink outdoor electrode 102 to an external electrode conducted to the driving IC 130. In such an ink jet head configuration, there is a problem that a portion other than the active region which originally contributes to ink ejection is very large, and the material cost is high, so that an inexpensive ink jet head cannot be manufactured.
[0014]
Further, it is necessary to extend the ink chamber electrode 101 to the flat portion 122b on the substrate 103 made of a piezoelectric element such as PZT having a high dielectric constant. For this reason, there is a problem that the capacitance of the substrate 103 increases, the drive voltage waveform to be applied when the actuator 100 is driven becomes dull, and high-speed printing by high-speed driving becomes difficult. The dullness of the print drive waveform can be improved by increasing the applied voltage, but the amount of heat generated by driving the actuator 100 increases by increasing the applied voltage, and the viscosity of the ink changes as the temperature of the actuator 100 rises. Therefore, there are a problem that stable and highly accurate printing cannot be performed, a problem that the driving IC 130 capable of applying a high voltage is expensive, and a problem that it is difficult to reduce power consumption.
[0015]
Therefore, by forming a low dielectric film in advance between the piezoelectric element and the ink chamber electrode 101 at a portion other than the active region in the ink chamber electrode 101 of the actuator 100, the capacitance of the substrate 103 in the portion other than the active region. To a level that can be almost ignored. However, an expensive ECR-CVD (Electron Cyclotron Resonance Chemical Vapor Deposition) apparatus is used to form a Si-N film having a low dielectric constant in a low temperature process with respect to PZT having a Curie point of about 200 ° C. Is required, and the manufacturing cost increases, and there is a problem that an inexpensive inkjet head cannot be manufactured.
[0016]
Japanese Patent Laid-Open No. 9-94954 discloses a configuration in which regions for extending the supply port 214a and the ink chamber electrode 213 are not formed in the longitudinal direction of the piezoelectric element, as shown in FIG. ing. In this configuration, ink is supplied to the ink chamber 214 from the supply port 214 a provided at the rear end of the active area of the substrate 210. The ink chamber electrode 213 formed in the ink chamber 214 extends from the ejection hole 212 side to the supply port 214a side, and is formed integrally with the ink chamber outer electrode 215 extending to the rear end portion of the substrate 210. The ink outdoor electrode 215 is electrically connected to the electrode 217 conducted to the driving IC 216.
[0017]
According to this configuration, since there is no portion other than the active region of the actuator 200, the material cost of the piezoelectric element can be reduced, but the problem that the capacitance of the substrate 210 increases remains. In addition, since the ink chamber electrode 213 is bent by 90 ° to the side surface of the actuator 200 to extend the ink chamber electrode 215, in the wafer state, the ink chamber electrode 213 is simultaneously formed by oblique vapor deposition when the ink chamber electrode 213 is formed. The electrode 215 cannot be formed.
[0018]
For this reason, the ink chamber electrode 213 and the ink chamber outer electrode 215 on the side surface of the actuator 200 are formed after the individual actuators 200 are cut out (divided into pieces) from the wafer. However, in order to extend the two ink chamber electrodes 213 facing each other in the ink chamber 214 in a state of being electrically conductive, oblique vapor deposition in at least two directions is further required. In addition, in order to separate the ink outdoor electrode 215 extending to the side surface of the actuator 200 for each ink chamber 214, patterning is performed in advance, or in the case where patterning is not performed, dicing or YAG laser is performed after being drawn out to a solid electrode. An electrode separation step is required. Thus, since the manufacturing process is complicated, there is a problem that productivity is poor, production yield is lowered, and production cost is increased.
[0019]
The lead wiring can also be formed by a plating technique, but there is a problem that the process becomes complicated because a patterning process or an electrode separation process is required as in the vapor deposition technique. In addition, the drawn electrode is also a bent portion drawn from the ink chamber 214 to the side surface of the actuator 200, and is likely to be disconnected in a later process or handling, resulting in poor production yield and environmental reliability. There was a problem.
[0020]
The object of the present invention is to prevent an increase in the substrate area without causing an increase in cost due to the use of expensive manufacturing equipment, the complexity of the manufacturing process, and a decrease in yield due to electrode disconnection, An inkjet head that can prevent a rise in material cost and can prevent high increase in the capacitance of the substrate and can perform high-precision and stable high-speed printing without increasing the amount of heat generated in the actuator. An electrode connection structure and a manufacturing method are provided.
[0021]
[Means for Solving the Problems]
The electrode connection structure of an ink jet head according to the present invention includes an ink chamber electrode electrically connected to an external drive circuit on each inner surface of a pair of partition walls sandwiching a groove-shaped ink chamber, and the ink chamber is formed from the external drive circuit. In an inkjet head that discharges ink in an ink chamber by deforming a partition by applying a drive pulse to an electrode, the substrate includes a substrate having a partition configured by forming a groove for an ink chamber reaching from one side to the other side The end face of the ink chamber electrode located only in the ink chamber groove is exposed at the other end face, and the exposed end face of the ink chamber electrode is electrically connected to the external drive circuit. The ink chamber electrode further includes a conductive layer for connection formed along the inner wall surface of the groove for the ink chamber, and the ink chamber electrode is formed so as to run in contact with the conductive layer for connection in the groove for the ink chamber. The end face of the connecting conductive layer located only inside is exposed at the other end face, and the exposed end face of the connecting conductive layer is electrically connected to the external drive circuit by an adhesive. Yes.
[0022]
The ink chamber electrode is located only in the ink chamber groove, and its end surface is exposed at the other end surface of the substrate. Therefore, the conventional ink chamber electrode was pulled out of the groove for the ink chamber for mounting, but in the present invention, this is not necessary, and almost no part other than the active area of the actuator is required, thus realizing a reduction in material cost. can do. In addition, since the drive frequency can be improved by reducing the capacitance, high-speed printing can be realized, and the drive voltage can be reduced, so that the withstand voltage of the drive IC can be reduced, thereby reducing the cost of the drive IC. In addition, reduction of driving power consumption can be realized.
[0024]
Also, Accordingly, it is possible to electrically connect both of the pair of ink chamber electrodes by simply connecting an external drive circuit to one of the pair of ink chamber electrodes opposed across the ink chamber groove.
[0025]
Preferably, in the electrode connection structure of the ink jet head, the cross-sectional area of the end surface of the ink chamber electrode exposed from the other end surface is 7 × 10. ^-Five mm ² That's it.
[0026]
As a result, an electrode made of ACA (Anisotropic Conductive Adhesive) or NCA (Non-Conductive Adhersive) is used when connecting to the electrode conducted later to the inkjet head driving IC. Sufficient reliability can be obtained in connection.
[0027]
In the electrode connection structure of the ink jet head, preferably, at least one of the ink chamber electrode and the connection conductive layer has a plated metal film on the surface.
[0028]
Since the ink chamber electrode and the conductive layer for connection are used as the electrode for connection to the external drive circuit, it is necessary to ensure a sufficient electrode thickness, and the throughput is slow in forming a metal film by a vacuum process such as vapor deposition or sputtering. Although there was a problem in productivity, only the seed layer for plating was thinly formed by a vacuum process, and by plating to the desired metal film thickness, productivity was improved and the film quality of the metal film itself was uniform. Therefore, the defect of peeling of the metal film, which can reduce the internal stress, is reduced, and an inexpensive, high quality, and highly reliable ink jet head can be realized.
[0029]
Preferably, the electrode connection structure of the ink jet head further includes a filler filling the pair of partition walls on the other end face side of the ink chamber groove. The filler includes any material of conductive resin and insulating resin.
[0030]
As a result, the conductive wafer or the insulating resin is filled in a predetermined area in the groove for the ink chamber in the subsequent dicing step by dicing, so that the channel wafer is increased in strength and can reduce damage during dicing. The production yield is improved and an inexpensive inkjet head can be realized.
[0031]
In the case of a conductive resin, a pair of ink chamber electrodes in the same ink chamber groove can be electrically connected by a conductive resin, and the conductive resin is used as an electrode for connection to an external drive circuit. Since the cross section can be used, a large connection area can be easily obtained and the connection stability is improved. In addition, in the case of an insulating resin, many additives having a relatively low linear expansion coefficient such as silica filler and alumina filler can be dispersed in the resin additive, making it easy to match the piezoelectric element with a low expansion coefficient. It is possible to prevent damage to the piezoelectric element due to thermal stress and the like, and environmental reliability is improved.
[0032]
Preferably, in the electrode connection structure of the ink jet head, the filler has at least one of an elastic modulus of 10 GPa or less in an environment of 100 ° C. or less and a linear expansion coefficient of 50 ppm / ° C. or less in an environment of 100 ° C. or less. It has these characteristics.
[0033]
Thereby, when the elastic modulus of the filling member is 10 GPa or less, the thermal stress between the piezoelectric element and the filling member can be relaxed by the elastic deformation of the filling material, and when the linear expansion coefficient of the filling material is 50 ppm / ° C. or less. Since the thermal stress which generate | occur | produces can be reduced, the inkjet head excellent in environmental reliability can be provided.
[0034]
In the electrode connection structure of the ink jet head, preferably, each of the ink chamber electrodes formed on each inner surface of the pair of partition walls is electrically connected by a connection conductive layer formed along the inner wall surface of the ink chamber groove. Connected.
[0035]
When each of the ink chamber electrodes formed on each inner surface of the pair of partition walls is not electrically connected by the connecting conductive layer and is electrically separated, it is conducted to the internal drive circuit. When the connection between the electrode and ACA is performed, it is necessary to connect the external electrode connected to the external drive circuit to the end face of each ink chamber electrode. However, if each of the pair of ink chamber electrodes is electrically connected by the conductive layer for connection, in the ACA electrode connection with the external electrode conducted to the external drive circuit, the external electrode of the external drive circuit is not connected. It is sufficient that at least one ACA conductive particle can be connected to the end face of one of the ink chamber electrodes. As a result, the density of the conductive particles in which ACA is dispersed can be reduced, which is advantageous in reducing the ACA material cost and insulative with the ink chamber electrode in the adjacent ink chamber groove, and facilitates a narrow pitch. It is possible to provide an inkjet head that is inexpensive and capable of high-definition printing.
[0036]
The inkjet head manufacturing method of the present invention includes a step of forming a plurality of ink chamber grooves at a predetermined pitch on the upper surface of a piezoelectric channel wafer polarized in the thickness direction; Forming a conductive layer for connection along the inner wall surface of the groove for the ink chamber; Ink chamber electrodes independent from each other are provided on the opposing surfaces of the plurality of ink chamber grooves. Riding while touching the conductive layer for connection Forming the cover wafer, bonding the cover wafer to the upper surface of the channel wafer, and cutting and dividing the bonded channel wafer and cover wafer in a direction crossing the longitudinal direction of the ink chamber groove. ing.
[0037]
Conventionally, the actuator has a large size and a complicated configuration, and the ink chamber electrode is drawn out of the ink chamber groove to the outside of the ink chamber groove for connection to an external drive circuit. On the other hand, according to the manufacturing method of the present invention, the end surface of the ink chamber electrode is exposed at the cut surface by cutting the channel wafer and the cover wafer after forming the ink chamber electrode in the ink chamber groove. Can do. Therefore, it is possible to electrically connect an external drive circuit to the exposed end face without drawing the ink chamber electrode from the ink chamber groove to the outside of the ink chamber groove.
[0038]
Since it is not necessary to draw out the ink chamber electrode outside the groove for the ink chamber in this way, almost no part other than the active area of the actuator is required, and the material cost can be reduced. In addition, since the drive frequency can be improved by reducing the electrostatic capacity, high-speed printing can be realized, and the drive voltage can be reduced, so that the withstand voltage of the drive IC can be reduced. Reduction of drive power consumption can be realized.
[0039]
Further, since it is not necessary to form an actuator having a complicated structure, the process can be simplified.
[0041]
further, As a result, in the connection with the electrode conducted to the external drive circuit to be performed later, by forming the thickness of the separately formed metal film, high mounting reliability can be secured, and at the same time, the electrode thickness can be reduced to the drive electrode. Since it is not necessary to increase the thickness, the throughput in the vacuum process is increased, the productivity is improved, and the driving load of the active area of the inkjet head driven in the share mode is not increased, so that low power consumption can be realized.
[0042]
Preferably, the ink jet head manufacturing method further includes a step of forming a filler so as to fill a predetermined region between the ink chamber electrodes facing each other in each of the plurality of ink chamber grooves. At the position where the filler is cut, the bonded channel wafer and cover wafer are cut.
[0043]
In this way, in the subsequent dicing process, the channel wafer is filled with the filling material made of conductive resin or insulating resin, so that the channel wafer is increased in strength and can reduce damage during dicing, so that the production yield can be reduced. And an inexpensive inkjet head can be realized. In the case of a conductive resin, a plurality of drive electrodes in the same ink chamber can be integrated into one by the conductive resin filling the ink chamber, and the cross section of the conductive resin can also be used as an external circuit connection electrode. Therefore, the connection area can be easily increased, and the connection stability is excellent. In addition, in the case of an insulating resin, since it is possible to disperse many additives having a relatively low linear expansion coefficient such as silica filler and alumina filler in the resin, matching with the linear expansion coefficient of the piezoelectric element is easy. Therefore, it is possible to prevent damage to the piezoelectric element due to thermal stress or the like, and it is possible to provide an ink jet head excellent in environmental reliability.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0045]
(Embodiment 1)
FIG. 1 is an exploded perspective view schematically showing the configuration of the ink jet head according to Embodiment 1 of the present invention. 2 is an end view (a) viewed from the direction of arrow II in FIG. 1, a schematic cross-sectional view along line IIB-IIB in FIG. 2 (a), and along a line IIC-IIC in FIG. 2 (a). It is a schematic sectional drawing (c).
[0046]
Referring to FIGS. 1 and 2, the inkjet head 1 of the present embodiment includes an actuator (substrate) 20, a plurality of actuator driving electrodes 27 and 28, an insulating resin 10, a cover member 30, and a nozzle. It mainly has a plate 25.
[0047]
The actuator 20 is made of a piezoelectric element such as PZT. In the actuator 20, each of the plurality of ink chamber grooves 26 a is formed in an array so as to penetrate from the ejection surface 23 to the rear end surface 21. A partition wall 29 is formed in each region of the actuator 20 sandwiched between the plurality of ink chamber grooves 26a. In the ink chamber groove 26a, two actuator driving electrodes (ink chamber electrodes) 27 and 28 are formed on the inner wall surface of the partition wall 29 in a state of facing each other.
[0048]
Each of the actuator driving electrodes 27 and 28 is formed in the upper half of the partition wall 29 and is made of, for example, a Cu (copper) thin film having a thickness of 0.5 μm. Further, the longitudinal end faces of the actuator driving electrodes 27 and 28 are exposed at the rear end face 21, and the exposed end face has a width of 0.5 μm and a length of 140 μm. The area is 7 × 10 ^-Five mm ² It is. The area of the end face exposed at the rear end face 21 of the actuator driving electrodes 27, 28 is 7 × 10. ^-Five mm ² The above is preferable.
[0049]
The insulating resin 10 contains, for example, silica filler, and is filled in the ink chamber groove 26a so as to close the rear end face 21 side of the ink chamber groove 26a. A portion of the ink chamber groove 26a excluding the actuator driving electrodes 27 and 28 and the insulating resin 10 is an ink chamber 26 that can be filled with ink. The insulating resin 10 prevents ink from flowing out from the ink chamber 26 to the rear end face 21 side. This insulating resin 10 has at least one of the following properties: an elastic modulus in an environment of 100 ° C. or less is 10 GPa or less, and a linear expansion coefficient in an environment of 100 ° C. or less is 50 ppm / ° C. or less. Is preferred.
[0050]
A nozzle plate 25 having minute nozzles 24 is attached to the ink discharge surface 23 of the actuator 20. A cover member 30 is attached to the upper surface of the actuator 20 so that the ink supply port 31 is positioned above the ink chamber 26.
[0051]
In the operation of ejecting ink droplets in the inkjet head 1, first, voltages having the same potential are applied to the two actuator driving electrodes 27 and 28 arranged in the same ink chamber groove 26 a, and the two surfaces of the partition wall 29 are opposed to each other. A voltage having an opposite phase is applied to the two actuator driving electrodes 28 and 27. As a result, the partition wall 29 serves as an actuator that is driven in the shear mode, and the ink pressure in the ink chamber 26 is controlled, thereby ejecting fine ink droplets from the nozzle 24.
[0052]
As shown in FIG. 3, a driving IC 40 is electrically connected to the actuator driving electrodes 27 and 28 of the inkjet head 1 of the present embodiment. Specifically, the outer leads 42 on the TAB tape 41 conducted to the driving IC 40 are electrically connected to both end faces exposed from the rear end faces 21 of the actuator driving electrodes 27 and 28 via the ACF 50. The By this connection, the outer lead 42 is electrically and collectively connected to both the actuator driving electrodes 27 and 28. In this connection, Ni (nickel) conductive particles of the ACF 50 are interposed between the end faces of the actuator driving electrodes 27 and 28 and the outer leads 42. The outer lead 42 can also be mechanically connected to the inkjet head 1 by curing the resin component of the ACF 50.
[0053]
In this connection, the area of each end face exposed from the rear end face 21 of the actuator driving electrodes 27 and 28 is 7 × 10 as described above. ^-Five mm ² Therefore, sufficient connection stability and connection reliability can be ensured.
[0054]
Note that the end face exposed from the rear end face 21 of the actuator driving electrodes 27 and 28 can be separately plated with Au to reduce the connection resistance with the outer lead 42. Heat generation due to the resistance component can be reduced. Similarly, the exposed surface 22 of the actuator drive electrodes 27 and 28 in the upper ink chamber can be electrically connected to an external drive circuit. At this time, the insulating resin 10 may be, for example, a conductive resin containing Ag (silver) filler. In this case, the actuator driving electrodes 27 and 28 in the same ink chamber 26 are electrically connected by the conductive resin 10. Can also be aggregated.
[0055]
In addition, since the conductive particle cross-sectional area of the conductive resin 10 is included as an effective electrode area for connecting the outer leads 42 on the small cut surface, the actuator driving electrodes 27 and 28 can be further reduced in thickness, thereby improving productivity. effective. Further, a material having a small linear expansion coefficient, such as silica filler or carbon particles, may be dispersed in the conductive resin 10, and in this case, the PZT linear expansion coefficient of the material of the actuator 20 can be approached. For this reason, there is an effect of improving the heat stress reliability by matching the linear expansion coefficient of the conductive resin 10 filled in the ink chamber groove 26a and PZT.
[0056]
Next, a method for manufacturing the ink jet head of the above-described embodiment will be described.
[0057]
4 to 6 are views showing the method of manufacturing the ink jet head according to the first embodiment of the present invention in the order of steps, FIGS. 4 and 5 are perspective views, and FIG. 6 is a sectional view.
[0058]
Referring to FIG. 4, first, dry film resist 70 is laminated on one surface of piezoelectric element wafer (channel wafer) 20 polarized in the thickness direction and cured. Thereafter, the channel wafer 20 is half-diced using a dicing blade of a dicer to form the ink chamber groove 26a.
[0059]
After forming a plurality of ink chamber grooves 26a (ink chamber array) in this way, a metal that becomes an electrode material such as Al or Cu is obliquely deposited from a direction perpendicular to the longitudinal direction of the ink chamber grooves 26a. By performing this operation from the left and right directions with respect to the longitudinal direction of the ink chamber groove 26a, the metal electrodes 27 and 28 are formed on the surface of the partition wall 29. The metal electrodes 27, 28 are formed to a depth of about ½ in the depth direction of the ink chamber groove 26 a by the shadowing effect of the dry film resist 70 and each partition wall 29.
[0060]
Thereafter, the dry film resist 70 is lifted off, so that no electrode is formed on the upper surface of the partition wall 29, and electrical separation between the ink chamber grooves 26a can be reliably performed.
[0061]
Referring to FIG. 5, liquid insulating resin 10 is used in an ink chamber with a width of 1 mm using a dispenser or the like in a direction orthogonal to the ink chamber array (that is, a direction orthogonal to the longitudinal direction of ink chamber groove 26a). One character is applied and supplied onto the groove 26a and the partition wall 29. At this time, if the viscosity of the insulating resin 10 is set to 10000 cps or less, the insulating resin 10 is naturally filled in the ink chamber groove 26a. In addition, it has been found that if the viscosity is 1000000 cps or less, the viscosity decreases with increasing temperature in the curing step and is filled before the curing reaction. For this reason, a filler of 1000000 cps or less can be used as the insulating resin 10 substantially.
[0062]
Thereafter, the insulating resin 10 is cured by being left in an oven at 100 ° C. for 1 hour. Alternatively, the resin may be cured on the hot plate. In this case, the active area portion of the actuator 20 is activated by circulating a Peltier element or a coolant so that it can be locally cooled in the hot plate. By performing forced cooling of the area, it is possible to reduce thermal damage to the actuator 20. Further, the insulating resin 10 can be cured at room temperature without performing heat curing.
[0063]
The insulating resin 10 adhering to the partition walls 29 is removed by polishing with 600th and 1200th wrapping films. Thereby, the flatness of the channel wafer 20 and the cover wafer (not shown) can be ensured at the time of wafer bonding performed later, and good wafer bonding can be performed.
[0064]
With reference to FIG. 6, a cover wafer 30 made of a piezoelectric element having a counterbore for the ink supply port 31 is prepared. The cover wafer 30 is a cover member that forms an ink supply port 31 and seals the upper portion of the ink chamber 26 when the ink jet head is configured later. Usually, the cover wafer 30 is made of the same material as that of the piezoelectric element constituting the actuator 20 in order to improve the matching of the thermal expansion coefficient with the actuator 20, but inexpensive alumina ceramics having a relatively close thermal expansion coefficient are used. May be used.
[0065]
The wafer 20 on which the ink chamber array is formed and the cover wafer 30 are bonded with a commercially available adhesive. At this time, alignment is performed so that the portion filled with the insulating resin 10 comes to the center portion of the spot facing portion for the ink supply port 31 of the cover wafer 30. Thereafter, the channel wafer 20 and the cover wafer 30 are separated by a dicing blade of a dicer at a spot facing portion for the ink supply port 31 and a filling portion of the insulating resin 10 at a dicing line indicated by a broken line in the drawing. It is cut (divided into small pieces).
[0066]
At this time, the insulating resin 10 and the electrodes 27 and 28 are exposed on the cut surface, and the electrode pressing load is applied to the entire surface of the external circuit electrode in electrical connection with the external circuit conducted to the driving IC connected later. It is possible to prevent the external circuit electrode from being damaged due to local concentration of the pressing force.
[0067]
The insulating resin 10 is made of an epoxy resin in which a silica filler is dispersed, and the linear expansion coefficient is adjusted to 50 ppm / ° C. Therefore, in the actuator 20 made of a normal epoxy resin containing no filler, an epoxy resin in which the silica filler used in the present embodiment is dispersed, compared to the case where a resin crack occurred early in the temperature cycle test. Then, it is excellent in connection reliability with the actuator.
[0068]
In the present embodiment, the actuator drive electrodes 27 and 28 are located only in the ink chamber groove 26 a, and their end surfaces are exposed at the rear end surface 21 of the substrate 20. Therefore, the actuator driving electrode has been drawn out of the groove for the ink chamber for mounting in the past, but this is not necessary in this embodiment, and almost no part other than the active area of the actuator is required, reducing the material cost. Can be realized. In addition, since the drive frequency can be improved by reducing the capacitance, high-speed printing can be realized, and the drive voltage can be reduced, so that the withstand voltage of the drive IC can be reduced, thereby reducing the cost of the drive IC. In addition, reduction of driving power consumption can be realized.
[0069]
The cross-sectional area of each end face of the actuator driving electrodes 27 and 28 exposed from the rear end face 21 is 7 × 10. ^-Five mm ² That's it. Thereby, sufficient reliability can be obtained in the electrode connection by ACA or NCA when connecting to the electrode conducted to the inkjet head driving IC to be performed later.
[0070]
Each of the actuator driving electrodes 27 and 28 has a plated metal film on the surface. Since the actuator drive electrodes 27 and 28 are used as connection electrodes to an external drive circuit, it is necessary to secure a sufficient electrode thickness. In the case of forming a metal film by a vacuum process such as vapor deposition or sputtering, throughput is slow and production is performed. There was a problem with sex. However, by forming only the plating seed layer by a thin vacuum process and forming it to the desired metal film thickness by plating, productivity can be improved, the film quality of the metal film itself is uniform, and internal stress can be reduced. The defect of peeling of the metal film is reduced, and an ink jet head that is inexpensive, has high quality stability, and high reliability can be realized.
[0071]
In addition, the filler 10 includes any one of a conductive resin and an insulating resin. As a result, since the conductive resin or the insulating resin is filled in a predetermined region in the ink chamber groove 26a in the fragmentation step by dicing performed later, the channel wafer is increased in strength and can reduce damage during dicing. As a result, the production yield is improved and an inexpensive inkjet head can be realized.
[0072]
In the case of a conductive resin, a pair of actuator drive electrodes 27 and 28 in the same ink chamber groove 26a can be electrically connected by a conductive resin and connected to an external drive circuit. As the cross section of the conductive resin can be used, the connection area can be easily increased, and the connection stability is improved. In addition, in the case of an insulating resin, many additives having a relatively low linear expansion coefficient such as silica filler and alumina filler can be dispersed in the resin additive, making it easy to match the piezoelectric element with a low expansion coefficient. It is possible to prevent damage to the piezoelectric element due to thermal stress and the like, and environmental reliability is improved.
[0073]
Further, the filler 10 has at least one of the properties that the elastic modulus in an environment of 100 ° C. or less is 10 GPa or less and the linear expansion coefficient in an environment of 100 ° C. or less is 50 ppm / ° C. or less. Thereby, when the elastic modulus of the filler 10 is 10 GPa or less, the thermal stress between the piezoelectric element and the filler can be relaxed by elastic deformation of the filler 10, and the linear expansion coefficient of the filler 10 is 50 ppm / ° C. Since the generated thermal stress can be reduced in the following cases, an ink jet head excellent in environmental reliability can be provided.
[0074]
Further, in the manufacturing method of the present embodiment, it is not necessary to form the actuator 20 having a complicated structure, so that the process can be simplified.
[0075]
Further, the filling material 10 is formed so as to fill a predetermined region between the actuator driving electrodes 27 and 28 facing each other in each of the plurality of ink chamber grooves 26a, and bonding is performed at a position where the filling material 10 is cut. The subsequent channel wafer 20 and cover wafer 30 are cut.
[0076]
In this way, in the subsequent dicing step by dicing, since the filling material 10 made of conductive resin or insulating resin is filled in the ink chamber groove 26a, the channel wafer 20 is increased in strength and damaged during dicing. Can be reduced, the production yield can be improved, and an inexpensive inkjet head can be realized.
[0077]
(Embodiment 2)
FIG. 7 is an exploded perspective view schematically showing the configuration of the ink jet head according to Embodiment 2 of the present invention. 8 is an end view (a) viewed from the direction of arrow VIII in FIG. 7, a schematic sectional view along line VIIIB-VIIIB in FIG. 8A, and a line VIIIC-VIIIC in FIG. 8A. It is a schematic sectional drawing (c).
[0078]
7 and 8, the configuration of the ink jet head of the present embodiment is different from the configuration of the first embodiment in that a metal film (conductive layer for connection) 80 is added. The metal film 80 is formed along the inner wall surface of the ink chamber groove 26 a, and is formed so that the end surface is exposed on the rear end surface 21 of the actuator 20. Each of the actuator driving electrodes 27 and 28 is formed so as to run in contact with the metal film 80 in the ink chamber groove 26a, and its end face is also exposed from the rear end face 21a.
[0079]
The actuator driving electrodes 27 and 28 are made of, for example, Al having a thickness of 0.1 μm. The metal film 80 conducted to the actuator driving electrodes 27 and 28 is formed of a 1 μm thick Ni electroless plating layer and flash after a Cr (chromium) adhesion layer and a Cu seed layer are formed by sputtering in the ink chamber groove 26a. It has a configuration in which an Au plating layer is formed. Since the metal film 80 is formed on the entire inner wall portion of the ink chamber groove 26a having a thickness of about 1 μm, a depth of 280 μm, and a width of 40 μm, the end face exposed at the rear end face 21 is exposed. Has a cross-sectional area of about 60 × 10 ^-Five mm ² It is.
[0080]
In addition, since it is substantially the same as the structure of Embodiment 1 mentioned above about the structure other than this, the same code | symbol is attached | subjected about the same member and the description is abbreviate | omitted.
[0081]
In the ink jet head according to the present embodiment, on one end of the actuator driving electrodes 27 and 28 and the end face exposed from the rear end face 21 of the metal film 80, the TAB tape 41 is connected to the driving IC 40 as shown in FIG. The outer leads 42 are directly connected. In this connection, the NCF 51 is interposed between the TAB tape 41 or the outer lead 42 and the actuator 20 and cured, whereby the both can be mechanically connected.
[0082]
At this time, the area of the end face of the metal film 80 is 60 × 10 6. ^-Five mm ² Therefore, sufficient connection stability and connection reliability can be ensured. Also, the electrode end surface of the ink chamber upper portion 22 can be electrically connected to an external circuit in the same manner as described above. At this time, the insulating resin 10 may be, for example, a conductive resin containing an Ag filler. In this case, the conductive resin cross-sectional area of the conductive resin is also included as an electrode area effective for outer lead connection at the small cut surface. Therefore, there is an effect of further improving connection stability and connection reliability.
[0083]
Next, a method for manufacturing the ink jet head of the present embodiment will be described.
10 to 13 are views showing the method of manufacturing the ink jet head according to the second embodiment of the present invention in the order of steps, FIGS. 10 and 13 are sectional views, and FIGS. 11 and 12 are perspective views. .
[0084]
Referring to FIG. 10, as in the first embodiment, first, a dry film resist 70 is laminated on one surface of a piezoelectric element wafer (channel wafer) 20 polarized in the thickness direction and cured. Thereafter, the channel wafer 20 is half-diced using a dicing blade of a dicer to form the ink chamber groove 26a.
[0085]
After forming a plurality of ink chamber grooves 26a (ink chamber array) in this way, a metal mask 82 having an opening corresponding to the rear end portion of the ink chamber grooves 26a is disposed, and a Cr adhesion layer is formed by sputtering. Is formed on the opening portion of the metal mask 82 with a thickness of 0.05 μm and a Cu seed layer with a thickness of 0.05 μm.
[0086]
Next, an electroless Ni plating (not shown) is formed with a thickness of 1 μm, and a flash Au plating is formed with a thickness of 0.05 μm on the portion where the Cu seed layer is attached.
[0087]
Referring to FIG. 11, an Al electrode is obliquely deposited with a thickness of 0.1 μm from the direction perpendicular to the longitudinal direction of ink chamber groove 26a. By performing this operation from the left and right directions with respect to the longitudinal direction of the ink chamber groove 26a, the metal electrodes 27 and 28 are formed on the surface of the partition wall 29. Due to the shadowing effect of the dry film resist 70 and the partition walls 29, the metal electrodes 27 and 28 are formed to about ½ of the depth direction of the ink chamber groove 26 a.
[0088]
Thereafter, the dry film resist 70 is lifted off, so that no electrode is formed on the upper surface of the partition wall 29, and electrical separation between the ink chamber grooves 26a can be reliably performed.
[0089]
Referring to FIG. 12, the ink chamber groove having a width of 1 mm using a dispenser or the like with liquid insulating resin 10 in a direction orthogonal to the ink chamber array (that is, a direction orthogonal to the longitudinal direction of ink chamber groove 26a). One letter is applied onto 26a and partition wall 29. At this time, if the viscosity of the insulating resin 10 is set to 10000 cps or less, the insulating resin 10 is naturally filled in the ink chamber groove 26a.
[0090]
Thereafter, the insulating resin 10 is cured by being left in an oven at 100 ° C. for 1 hour. The insulating resin 10 adhering to the partition walls 29 is removed by polishing with 600th and 1200th wrapping films. Thereby, the flatness of the channel wafer 20 and the cover wafer (not shown) can be ensured at the time of wafer bonding performed later, and good wafer bonding can be performed.
[0091]
Referring to FIG. 13, a cover wafer 30 made of a piezoelectric element having a counterbore for the ink supply port 31 is prepared. The cover wafer 30 is a cover member that forms an ink supply port 31 and seals the upper portion of the ink chamber 26 when the ink jet head is configured later. Usually, the cover wafer 30 is made of the same material as that of the piezoelectric element constituting the actuator 20 in order to improve the matching of the thermal expansion coefficient with the actuator 20, but inexpensive alumina ceramics having a relatively close thermal expansion coefficient are used. May be used.
[0092]
The wafer 20 on which the ink chamber array is formed and the cover wafer 30 are bonded with a commercially available adhesive. At this time, alignment is performed so that the portion filled with the insulating resin 10 comes to the center portion of the spot facing portion for the ink supply port 31 of the cover wafer 30, and both are bonded together as in the first embodiment. Thereafter, the channel wafer 20 and the cover wafer are separated by a dicing blade of a dicer at a spot facing portion for the ink supply port 31 and a filling portion of the insulating resin 10 in the dicing line indicated by a broken line in FIG. 30 is divided and cut, and is divided into individual actuators to complete the actuators.
[0093]
At this time, the end surfaces of the actuator driving electrodes 27 and 28 made of, for example, Al, and the end surface of the metal film 80 made of Au / Ni / Cu / Cr electrically connected thereto are exposed at the cut surface. For connection with a lead conducted to the driving IC to be performed later, each end face of the metal film 80 and the actuator driving electrodes 27 and 28 is configured as an external circuit connecting electrode. The load can be received over the entire cut surface of the actuator, and it is possible to prevent the external circuit electrode from being damaged due to local concentration of the pressing force.
[0094]
The insulating resin 10 is made of an epoxy resin in which silica filler is dispersed, and the elastic modulus is adjusted to 10 GPa. Therefore, the insulating resin 10 is interposed between the insulating resin filled in the ink chamber and the piezoelectric element. Since the generated thermal stress can be relaxed by elastic deformation of the insulating resin, the connection reliability is excellent.
[0095]
In the present embodiment, the same effect as in the first embodiment described above can be obtained.
In the present embodiment, the metal film 80 is electrically connected to the actuator driving electrodes 27 and 28. Thus, the external drive circuit is simply connected to one of the pair of actuator drive electrodes 27 and 28 facing each other across the ink chamber groove 26a, so that both of the pair of actuator drive electrodes 27 and 28 are electrically connected. It becomes possible to connect to.
[0096]
At least one of the actuator driving electrodes 27 and 28 and the metal film 80 has a plated metal film on the surface. Since the actuator driving electrodes 27 and 28 and the metal film 80 are used as electrodes for connection to an external driving circuit, it is necessary to ensure a sufficient electrode thickness, and throughput is required in forming a metal film by a vacuum process such as vapor deposition or sputtering. However, the productivity was improved by forming only the seed layer for plating thinly by a vacuum process and forming it to the desired metal film thickness by plating. The defect of the metal film peeling that can reduce the internal stress with uniform film quality is reduced, and an inkjet head that is inexpensive, has high quality stability, and high reliability can be realized.
[0097]
In addition, each of the actuator driving electrodes 27 and 28 formed on each inner surface of the pair of partition walls 29 is electrically connected by a metal film 80 formed along the inner wall surface of the ink chamber groove 26a. Yes. When the actuator driving electrodes 27 and 28 formed on the inner side surfaces of the pair of partition walls 29 are not electrically connected by the metal film 80 and are electrically separated, the internal drive When an ACA connection is made with an electrode that is conductive to the circuit, it is necessary to connect the external electrode that is conductive to the external drive circuit to the end faces of the actuator drive electrodes 27 and 28.
[0098]
However, if each of the pair of actuator driving electrodes 27 and 28 is electrically connected by the metal film 80, in the electrode connection in the ACA with the external electrode conducted to the external driving circuit, the external driving circuit It is only necessary that the external electrode can be connected to the end face of one of the actuator driving electrodes 27 and 28 by at least one ACA conductive particle. As a result, the density of conductive particles in which ACA is dispersed can be reduced, which is advantageous for reducing the cost of ACA material and insulating the actuator driving electrodes 27 and 28 in the adjacent ink chamber groove 26a. Therefore, it is possible to provide an ink jet head that can be easily manufactured and that can be printed at low cost and with high definition.
[0099]
Further, the manufacturing method according to the present embodiment includes a step of forming the metal film 80 along the inner wall surface of the ink chamber groove 26a, and the actuator driving electrodes 27 and 28 are formed so as to be in contact with the metal film 80. The Thereby, in the connection with the electrode conducted to the external drive circuit to be performed later, by forming the metal film separately formed thick, high mounting reliability can be secured and at the same time, the actuator drive electrodes 27 and 28 can be secured. Since it is not necessary to increase the electrode thickness, the throughput in the vacuum process is increased, the productivity is improved, and the drive load on the active area of the inkjet head driven in the share mode is not increased, resulting in low power consumption. it can.
[0100]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0101]
【The invention's effect】
In the ink jet head electrode connection structure of the present invention, it is not necessary to pull out the ink chamber electrode out of the groove for the ink chamber as in the conventional case, and almost no part other than the active area of the actuator is required, thereby realizing reduction in material cost. Can do. In addition, since the drive frequency can be improved by reducing the capacitance, high-speed printing can be realized, and the drive voltage can be reduced, so that the withstand voltage of the drive IC can be reduced, thereby reducing the cost of the drive IC. In addition, reduction of driving power consumption can be realized.
[0102]
In the electrode connection structure of the above inkjet head The And a connecting conductive layer electrically connected to the ink chamber electrode. The end face of the connection conductive layer located only in the ink chamber groove is exposed at the other end face, and is electrically connected to the external drive circuit at the exposed end face of the connection conductive layer. Accordingly, it is possible to electrically connect both of the pair of ink chamber electrodes by simply connecting an external drive circuit to one of the pair of ink chamber electrodes opposed across the ink chamber groove.
[0103]
Preferably, in the electrode connection structure of the ink jet head, the cross-sectional area of the end surface of the ink chamber electrode exposed from the other end surface is 7 × 10. ^-Five mm ² That's it. Thereby, sufficient reliability can be obtained in the electrode connection by ACA or NCA when connecting to the electrode conducted to the inkjet head driving IC to be performed later.
[0104]
In the electrode connection structure of the ink jet head, preferably, at least one of the ink chamber electrode and the connection conductive layer has a plated metal film on the surface. Since the ink chamber electrode and the conductive layer for connection are used as the electrode for connection to the external drive circuit, it is necessary to ensure a sufficient electrode thickness, and the throughput is slow in forming a metal film by a vacuum process such as vapor deposition or sputtering. Although there was a problem in productivity, only the seed layer for plating was thinly formed by a vacuum process, and by plating to the desired metal film thickness, productivity was improved and the film quality of the metal film itself was uniform. Therefore, the defect of peeling of the metal film, which can reduce the internal stress, is reduced, and an inexpensive, high quality, and highly reliable ink jet head can be realized.
[0105]
Preferably, the electrode connection structure of the ink jet head further includes a filler filling the pair of partition walls on the other end face side of the ink chamber groove. The filler includes any material of conductive resin and insulating resin. As a result, the conductive wafer or the insulating resin is filled in a predetermined area in the groove for the ink chamber in the subsequent dicing step by dicing, so that the channel wafer is increased in strength and can reduce damage during dicing. The production yield is improved and an inexpensive inkjet head can be realized.
[0106]
In the case of a conductive resin, a pair of ink chamber electrodes in the same ink chamber groove can be electrically connected by a conductive resin, and the conductive resin is used as an electrode for connection to an external drive circuit. Since the cross section can be used, a large connection area can be easily obtained and the connection stability is improved. In addition, in the case of an insulating resin, many additives having a relatively low linear expansion coefficient such as silica filler and alumina filler can be dispersed in the resin additive, making it easy to match the piezoelectric element with a low expansion coefficient. It is possible to prevent damage to the piezoelectric element due to thermal stress and the like, and environmental reliability is improved.
[0107]
Preferably, in the electrode connection structure of the ink jet head, the filler has at least one of an elastic modulus of 10 GPa or less in an environment of 100 ° C. or less and a linear expansion coefficient of 50 ppm / ° C. or less in an environment of 100 ° C. or less. It has these characteristics. Thereby, when the elastic modulus of the filling member is 10 GPa or less, the thermal stress between the piezoelectric element and the filling member can be relaxed by the elastic deformation of the filling material, and when the linear expansion coefficient of the filling material is 50 ppm / ° C. or less. Since the thermal stress which generate | occur | produces can be reduced, the inkjet head excellent in environmental reliability can be provided.
[0108]
In the electrode connection structure of the ink jet head, preferably, each of the ink chamber electrodes formed on each inner surface of the pair of partition walls is electrically connected by a connection conductive layer formed along the inner wall surface of the ink chamber groove. Connected. When each of the ink chamber electrodes formed on each inner surface of the pair of partition walls is not electrically connected by the connecting conductive layer and is electrically separated, it is conducted to the internal drive circuit. When the connection between the electrode and ACA is performed, it is necessary to connect the external electrode connected to the external drive circuit to the end face of each ink chamber electrode. However, if each of the pair of ink chamber electrodes is electrically connected by the conductive layer for connection, in the ACA electrode connection with the external electrode conducted to the external drive circuit, the external electrode of the external drive circuit is not connected. It is sufficient that at least one ACA conductive particle can be connected to the end face of one of the ink chamber electrodes. As a result, the density of the conductive particles in which ACA is dispersed can be reduced, which is advantageous in reducing the ACA material cost and insulative with the ink chamber electrode in the adjacent ink chamber groove, and facilitates a narrow pitch. It is possible to provide an inkjet head that is inexpensive and capable of high-definition printing.
[0109]
According to the method of manufacturing an ink jet head of the present invention, the end surface of the ink chamber electrode can be exposed at the cut surface by cutting the channel wafer and the cover wafer after forming the ink chamber electrode in the ink chamber groove. it can. Therefore, it is possible to electrically connect an external drive circuit to the exposed end face without drawing the ink chamber electrode from the ink chamber groove to the outside of the ink chamber groove.
[0110]
Since it is not necessary to draw out the ink chamber electrode outside the groove for the ink chamber in this way, almost no part other than the active area of the actuator is required, and the material cost can be reduced. In addition, since the drive frequency can be improved by reducing the electrostatic capacity, high-speed printing can be realized, and the drive voltage can be reduced, so that the withstand voltage of the drive IC can be reduced. Reduction of drive power consumption can be realized.
[0111]
Further, since it is not necessary to form an actuator having a complicated structure, the process can be simplified.
[0112]
In the manufacturing method of the ink jet head described above The And a step of forming a connection conductive layer along the inner wall surface of the ink chamber groove. An ink chamber electrode is formed so as to be in contact with the connecting conductive layer. As a result, in the connection with the electrode conducted to the external drive circuit to be performed later, by forming the thickness of the separately formed metal film, high mounting reliability can be secured, and at the same time, the electrode thickness can be reduced to the drive electrode. Since it is not necessary to increase the thickness, the throughput in the vacuum process is increased and the productivity is improved. And The drive load on the active area of the inkjet head driven in the share mode does not increase, and low power consumption can be realized.
[0113]
Preferably, the ink jet head manufacturing method further includes a step of forming a filler so as to fill a predetermined region between the ink chamber electrodes facing each other in each of the plurality of ink chamber grooves. At the position where the filler is cut, the bonded channel wafer and cover wafer are cut. In this way, in the subsequent dicing process, the channel wafer is filled with the filling material made of conductive resin or insulating resin, so that the channel wafer is increased in strength and can reduce damage during dicing, so that the production yield can be reduced. And an inexpensive inkjet head can be realized. In the case of a conductive resin, a plurality of drive electrodes in the same ink chamber can be integrated into one by the conductive resin filling the ink chamber, and the cross section of the conductive resin can also be used as an external circuit connection electrode. Therefore, the connection area can be easily increased, and the connection stability is excellent. In addition, in the case of an insulating resin, since it is possible to disperse many additives having a relatively low linear expansion coefficient such as silica filler and alumina filler in the resin, matching with the linear expansion coefficient of the piezoelectric element is easy. Therefore, it is possible to prevent damage to the piezoelectric element due to thermal stress or the like, and it is possible to provide an ink jet head excellent in environmental reliability.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view schematically showing a configuration of an ink jet head according to Embodiment 1 of the present invention.
2A is an end view as viewed from the direction of arrow II in FIG. 1, FIG. 2B is a schematic cross-sectional view taken along the line IIB-IIB in FIG. 1A, and FIG. It is a schematic sectional drawing which follows the IIC-IIC line.
3 is a diagram showing a state in which an external drive circuit is connected to the inkjet head of FIG. 2, wherein (a) corresponds to an end view seen from the II direction of FIG. 1, and (b) is IIIB of (a). It is a schematic sectional drawing in alignment with -IIIB, (c) is a schematic sectional drawing in alignment with the IIIC-IIIC line of (a).
4 is a schematic perspective view showing a first step of the method of manufacturing the ink jet head according to the first embodiment of the present invention. FIG.
FIG. 5 is a schematic perspective view showing a second step of the method of manufacturing the inkjet head in the first embodiment of the invention.
6 is a schematic cross-sectional view showing a third step of the method of manufacturing the ink jet head according to the first embodiment of the present invention. FIG.
FIG. 7 is an exploded perspective view schematically showing a configuration of an ink jet head according to a second embodiment of the present invention.
8A is an end view as viewed from the direction of arrow VIII in FIG. 7, FIG. 8B is a schematic cross-sectional view taken along line VIIIB-VIIIB in FIG. 7A, and FIG. It is a schematic sectional drawing in alignment with a VIIIC-VIIIC line.
9 is a diagram illustrating a state in which an external drive circuit is connected to the inkjet head of FIG. 8, wherein (a) corresponds to an end view as viewed from the VIII direction of FIG. 7, and (b) is an IXB of (a). It is a schematic sectional drawing in alignment with -IXB line, (c) is a schematic sectional drawing in alignment with the IXC-IXC line of (a).
FIG. 10 is a schematic cross-sectional view showing a first step of a method of manufacturing an ink jet head according to Embodiment 2 of the present invention.
FIG. 11 is a schematic perspective view showing a second step of the method of manufacturing the ink jet head in the second embodiment of the present invention.
FIG. 12 is a schematic perspective view showing a third step of the method of manufacturing the ink jet head in the second embodiment of the present invention.
FIG. 13 is a schematic cross-sectional view showing a fourth step of the method of manufacturing an ink jet head in the second embodiment of the present invention.
FIG. 14 is a side sectional view showing a first example of an electrode connection structure of a conventional ink jet head.
FIG. 15 is a side cross-sectional view showing a second example of an electrode connection structure of a conventional inkjet head.
FIG. 16 is a side sectional view showing a third example of an electrode connection structure of a conventional inkjet head.
FIG. 17 is a perspective view showing a main part of a conventional method for manufacturing an inkjet head.
FIG. 18 is a side sectional view showing a fourth example of an electrode connection structure of a conventional inkjet head.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inkjet head, 10 Insulating resin, 20 Actuator, 24 nozzle hole, 25 Nozzle plate, 26 Ink chamber, 27, 28 Electrode, 29 partition, 30 Cover plate, 31 Ink supply part, 40 Drive IC (external drive circuit) 41 TAB tape, 42 Outer leads.

Claims (8)

An ink chamber electrode electrically connected to an external drive circuit is formed on each inner surface of a pair of partition walls sandwiching the groove-shaped ink chamber, and a drive pulse is applied from the external drive circuit to the ink chamber electrode. In an inkjet head that discharges ink in the ink chamber by deforming the partition,
A substrate having the partition wall formed by forming a groove for an ink chamber reaching from the one side surface to the other side surface;
An end surface of the ink chamber electrode located only in the ink chamber groove is exposed at the other end surface, and the exposed end surface of the ink chamber electrode is electrically connected to the external drive circuit ,
A connection conductive layer formed along the inner wall surface of the ink chamber groove;
The ink chamber electrode is formed so as to run up in contact with the connection conductive layer in the ink chamber groove,
An end face of the connection conductive layer located only in the ink chamber groove is exposed at the other end face, and the exposed end face of the connection conductive layer is electrically connected to the external drive circuit by an adhesive. It is characterized in that is, the electrode connection structure of the ink jet head. ^2. The electrode connection structure of an ink jet head according to claim 1, wherein a cross-sectional area of an end face of the ink chamber electrode exposed from the other end face is 7 × 10 ⁻⁵ mm ² or more. The electrode connection structure for an ink jet head according to claim 1, wherein at least one of the ink chamber electrode and the connection conductive layer has a plated metal film on a surface thereof . A filler for filling so as to close the space between the pair of partition walls on the other end face side of the ink chamber groove;
The filler is characterized by comprising any of the material of the conductive resin and insulating resin, the electrode connection structure of the ink jet head according to any one of claims 1-3. The filler has an elastic modulus of 10 GPa or less in an environment of 100 ° C. or less and a linear expansion coefficient in an environment of 100 ° C. or less of 50 ppm / ° C. or less. The electrode connection structure of the inkjet head according to claim 4 . Each of the ink chamber electrodes formed on each inner surface of the pair of partition walls is electrically connected by the connecting conductive layer formed along the inner wall surface of the ink chamber groove. The electrode connection structure of an ink jet head according to claim 1 , wherein Forming a plurality of ink chamber grooves at a predetermined pitch on the upper surface of a piezoelectric channel wafer polarized in the thickness direction;
Forming a conductive layer for connection along the inner wall surface of the ink chamber groove;
Forming the ink chamber electrodes independent of each other on each of the opposing surfaces of the plurality of ink chamber grooves so as to run on the connection conductive layer ;
Adhering a cover wafer to the upper surface of the channel wafer;
A method of manufacturing an inkjet head, comprising: a step of cutting and dividing the channel wafer and the cover wafer after the bonding in a direction intersecting with a longitudinal direction of the ink chamber groove. Forming a filler so as to fill a predetermined region between the ink chamber electrodes facing each other in each of the plurality of ink chamber grooves,
Wherein in a position to cut the filler, the said channel wafer after bonding and wherein the cover wafer and wherein Rukoto is cut, a manufacturing method of an ink jet head according to claim 7.

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