JP2012056288A - Liquid ejection head and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress positional deviation and spread of a bump.SOLUTION: An individual electrode 18a and a conductive land 18b are formed on the surface 17a1 of a piezoelectric layer of an actuator unit 17. The land 18b is cylindrical, and is connected to the tip of an extension part 18a2 of the individual electrode 18a. The conductive bump 18d is housed in the hollow space of the land 18b. The land 18b and the terminal of FPC are joined together via the bump 18d, and driving voltage is applied to the individual electrode 18a via the land 18b.

Description

  The present invention relates to a liquid discharge head that discharges liquid such as ink and a method for manufacturing the same.

  In an inkjet head which is an example of a liquid ejection head, a technique for ejecting ink from an ejection port by a piezo method is known. For example, in Patent Document 1, when a driving voltage is applied to an individual electrode formed on the surface of a piezoelectric layer (piezoelectric sheet), an active portion (a portion sandwiched between the individual electrode and another electrode (common electrode) in the piezoelectric layer) Is displaced. As a result, the volume of the pressure chamber facing the individual electrode changes, and ink is ejected from the ejection port (nozzle opening). The individual electrodes are provided with conductive lands (land portions). The land and a terminal of a power supply member (FPC (Flexible Printed Circuit)) are joined through conductive bumps formed on the land.

Japanese Patent Laying-Open No. 2005-305847 (FIG. 8)

  By the way, the bump may be formed with a deviation from a desired position or may be formed larger than a desired size. That is, in plan view, the center of the bump may deviate from the center of the land, or the bump may spread outward from the outer edge of the land. In this case, the volume of the active part increases and the active part approaches the adjacent active part, so that structural crosstalk (a phenomenon in which the deformation of the active part affects the adjacent active part) can be prominent.

  An object of the present invention is to provide a liquid discharge head capable of suppressing the displacement and spread of bumps and a method for manufacturing the same.

  In order to achieve the above object, according to a first aspect of the present invention, a flow path unit in which a liquid flow path reaching a discharge port for discharging liquid through a pressure chamber whose volume changes is formed, a piezoelectric layer, and the piezoelectric layer An individual electrode disposed opposite to the pressure chamber in a direction orthogonal to the surface on the surface of the substrate, and a conductive land connected to the individual electrode and protruding in a direction orthogonal to the surface. An actuator unit that changes the volume of the pressure chamber when a drive voltage is applied to the individual electrode through the land, and is connected to the land at a tip surface of the land and the drive voltage. There is provided a liquid discharge head characterized in that a hole for accommodating a conductive bump supplied with a hole is opened.

  According to a second aspect of the present invention, a flow path unit manufacturing step for manufacturing a flow path unit in which a liquid flow path is formed that reaches a discharge port for discharging liquid through a pressure chamber whose volume changes, a piezoelectric layer, and the piezoelectric layer An electrode formed on the surface of the layer; and a conductive land connected to the individual electrode, and a volume of the pressure chamber is changed by applying a driving voltage to the individual electrode through the land. An actuator unit manufacturing step for manufacturing an actuator unit, the individual electrode forming step for forming the individual electrode on the surface, and the land projecting in a direction orthogonal to the surface and having a hole opened at the tip surface An actuator unit manufacturing process including a land forming process to be performed, and the individual electrode facing the pressure chamber in a direction orthogonal to the surface, A fixing step of fixing the Ju eta unit to the channel unit, and the bump forming step of forming a conductive bump in said bore, characterized by comprising a method of manufacturing a liquid discharge head is provided.

  According to the present invention, the bumps are accommodated in the holes opened in the front end surface of the land, so that the displacement and spread of the bumps can be suppressed.

1 is a schematic side view showing an internal structure of an ink jet printer to which an ink jet head according to an embodiment of the present invention is applied. It is a top view which shows the flow path unit and actuator unit of an inkjet head. FIG. 3 is an enlarged view showing a region III surrounded by an alternate long and short dash line in FIG. 2. FIG. 4 is a partial cross-sectional view taken along line IV-IV in FIG. 3. It is a longitudinal cross-sectional view of an inkjet head. (A) is a fragmentary sectional view of an actuator unit. (B) is a partial top view of an actuator unit. (C) is an enlarged view of a region C surrounded by a dashed line in (a). It is a fragmentary top view of an actuator unit which shows arrangement | positioning of a land and a dummy land. It is a flowchart which shows the manufacturing method of an inkjet head. (A), (b), (c) is the top view and sectional drawing when an individual electrode formation process, a land formation process, and a bump formation process are performed, respectively.

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

  First, an overall configuration of an ink jet printer 1 to which an ink jet head 10 according to an embodiment of the present invention is applied will be described with reference to FIG.

  The printer 1 has a rectangular parallelepiped casing 1a. A paper discharge unit 31 is provided on the top of the casing 1a. The internal space of the housing 1a can be divided into spaces A, B, and C in order from the top. Spaces A and B are spaces in which a paper transport path that continues to the paper discharge unit 31 is formed. In the space A, the conveyance of the paper P and the recording of the image on the paper P are performed. In the space B, an operation related to paper feeding is performed. In the space C, an ink cartridge 40 as an ink supply source is accommodated.

  In the space A, four inkjet heads 10, a transport unit 21 for transporting the paper P, a guide unit (described later) for guiding the paper P, and the like are arranged. Above the space A, a controller 1p that controls the operation of each part of the printer 1 including these mechanisms and controls the operation of the entire printer 1 is disposed.

  Based on image data supplied from the outside, the controller 1p is configured so that an image is recorded on the paper P. Ink ejection synchronized with the recording preparation operation, the paper P supply / conveyance / discharge operation, and the paper P conveyance Control operation, recovery performance maintenance operation (maintenance operation), etc.

  In addition to a CPU (Central Processing Unit) which is an arithmetic processing unit, the controller 1p includes a ROM (Read Only Memory), a RAM (Random Access Memory: including a nonvolatile RAM), an ASIC (Application Specific Integrated Circuit), an I / F. (Interface), I / O (Input / Output Port) and the like. The ROM stores programs executed by the CPU, various fixed data, and the like. The RAM temporarily stores data (for example, image data) necessary for executing the program. In the ASIC, image data is rewritten and rearranged (signal processing and image processing). The I / F performs data transmission / reception with a host device. I / O inputs / outputs detection signals of various sensors.

  Each head 10 is a line head having a substantially rectangular parallelepiped shape elongated in the main scanning direction. The four heads 10 are arranged at a predetermined pitch in the sub-scanning direction, and are supported by the housing 1a via the head frame 3. The head 10 includes a flow path unit 12, eight actuator units 17 (see FIG. 2), and a reservoir unit 11. During image recording, magenta, cyan, yellow, and black inks are ejected from the lower surfaces (ejection surfaces 10a) of the four heads 10, respectively. A more specific configuration of the head 10 will be described in detail later.

  As shown in FIG. 1, the transport unit 21 includes a belt roller 6, 7 and an endless transport belt 8 wound between both rollers 6, 7, and a nip roller 4 disposed on the outer side of the transport belt 8 and a peeling member. The plate 5 and the platen 9 disposed inside the conveyor belt 8 are included.

  The belt roller 7 is a drive roller, and is rotated by driving a conveyance motor (not shown), and rotates clockwise in FIG. As the belt roller 7 rotates, the conveyor belt 8 travels in the direction of the thick arrow in FIG. The belt roller 6 is a driven roller and rotates clockwise in FIG. 1 as the transport belt 8 travels. The nip roller 4 is disposed to face the belt roller 6 and presses the paper P supplied from the upstream guide portion (described later) against the outer peripheral surface 8 a of the transport belt 8. The peeling plate 5 is disposed so as to face the belt roller 7, and peels the paper P from the outer peripheral surface 8 a and guides it to the downstream guide portion (described later). The platen 9 is disposed to face the four heads 10 and supports the upper loop of the conveyor belt 8 from the inside. Thereby, a predetermined gap suitable for image recording is formed between the outer peripheral surface 8 a and the ejection surface 10 a of the head 10.

  The guide unit includes an upstream guide portion and a downstream guide portion disposed with the transport unit 21 interposed therebetween. The upstream guide portion has two guides 27 a and 27 b and a pair of feed rollers 26. The guide unit connects a paper feeding unit 1 b (described later) and the transport unit 21. The downstream guide portion has two guides 29 a and 29 b and two pairs of feed rollers 28. The guide unit connects the transport unit 21 and the paper discharge unit 31.

  In the space B, the paper feeding unit 1b is arranged. The paper feed unit 1b has a paper feed tray 23 and a paper feed roller 25, and the paper feed tray 23 is detachable from the housing 1a. The paper feed tray 23 is a box that opens upward, and stores a plurality of types of paper P. The paper feed roller 25 feeds the uppermost paper P in the paper feed tray 23 and supplies it to the upstream guide unit.

  As described above, in the spaces A and B, the paper transport path from the paper feed unit 1b to the paper discharge unit 31 via the transport unit 21 is formed. Based on the recording command, the controller 1p drives a paper feed motor (not shown) for the paper feed roller 25, a feed motor (not shown) for the feed roller of each guide section, a conveyance motor, and the like. The paper P sent out from the paper feed tray 23 is supplied to the transport unit 21 by the feed roller 26. When the paper P passes directly below each head 10 in the sub-scanning direction, ink is sequentially ejected from the ejection surface 10a, and a color image is recorded on the paper P. The ink ejection operation is performed based on a detection signal from the paper sensor 32. The paper P is then peeled off by the peeling plate 5 and conveyed upward by the two feed rollers 28. Further, the paper P is discharged from the upper opening 30 to the paper discharge unit 31.

  Here, the sub-scanning direction is a direction parallel to the conveyance direction of the paper P by the conveyance unit 21, and the main scanning direction is a direction parallel to the horizontal plane and orthogonal to the sub-scanning direction.

  In the space C, the ink unit 1c is detachably arranged with respect to the housing 1a. The ink unit 1 c includes a cartridge tray 35 and four cartridges 40 accommodated in the tray 35 side by side. Each cartridge 40 supplies ink to the corresponding head 10 via an ink tube (not shown).

  Next, the configuration of the head 10 will be described in more detail with reference to FIGS. In FIG. 3, the pressure chamber 16 and the aperture 15 which are located below the actuator unit 17 and should be indicated by dotted lines are indicated by solid lines.

  As shown in FIG. 5, the head 10 is a stacked body in which the flow path unit 12, the actuator unit 17, the reservoir unit 11, and the substrate 64 are stacked. Among these, the actuator unit 17, the reservoir unit 11, and the substrate 64 are accommodated in a space formed by the upper surface 12 x of the flow path unit 12 and the cover 65. In the space, an FPC (flat flexible substrate) 50 electrically connects the actuator unit 17 and the substrate 64. A driver IC 57 is mounted on the FPC 50.

  As shown in FIG. 5, the cover 65 includes a top cover 65a and an aluminum side cover 65b. The cover 65 is a box that opens downward, and is fixed to the upper surface 12 x of the flow path unit 12. The driver IC 57 contacts the inner surface of the side cover 65b and is thermally coupled to the cover 65b. In order to ensure the thermal coupling, the driver IC 57 is urged toward the side cover 65b by an elastic member (for example, sponge) 58 fixed to the side surface of the reservoir unit 11.

  The reservoir unit 11 is a laminated body in which four metal plates 11a to 11d are bonded to each other. An ink flow path including an ink reservoir reservoir 72 is formed inside the reservoir unit 11. One end of the ink flow path is connected to the cartridge 40 via a tube or the like, and the other end is connected to the flow path unit 12. As shown in FIG. 5, irregularities are formed on the lower surface of the plate 11d, and a space is formed between the plate 11d and the upper surface 12x by the concave portion. The actuator unit 17 is fixed to the upper surface 12x in the space, leaving a slight gap above the FPC 50. An ink outflow channel 73 is formed in the plate 11d. The flow path 73 is open to the tip surface of the convex portion on the lower surface of the plate 11d (that is, the bonding surface with the upper surface 12x).

  The flow path unit 12 is a laminated body in which nine rectangular metal plates 12a, 12b, 12c, 12d, 12e, 12f, 12g, 12h, and 12i (see FIG. 4) having substantially the same size are bonded to each other. As shown in FIG. 2, an opening 12 y is formed on the upper surface 12 x of the flow path unit 12 and is connected to the opening 73 a of the ink outflow flow path 73. Inside the flow path unit 12, an ink flow path that is connected to the ejection port 14a from the opening 12y is formed. As shown in FIGS. 2, 3, and 4, the ink channel includes a manifold channel 13 having an opening 12y at one end, a sub-manifold channel 13a branched from the manifold channel 13, and a sub-manifold channel. The individual flow path 14 from the outlet 13a to the discharge port 14a through the pressure chamber 16 is included.

  The individual flow path 14 is formed for each discharge port 14a, and includes an aperture 15 functioning as a flow path resistance adjusting aperture and a pressure chamber 16 opened to the upper surface 12x, as shown in FIG. As shown in FIG. 3, each of the pressure chambers 16 has a substantially rhombus shape, and is arranged in a matrix on the upper surface 12x, thereby constituting a total of eight pressure chamber groups that occupy a substantially trapezoidal region in plan view. . Similarly to the pressure chambers 16, the discharge ports 14 a are arranged in a matrix on the discharge surface 10 a, thereby constituting a total of eight discharge port groups that occupy a substantially trapezoidal region in plan view. The pressure chamber group and the discharge group correspond individually, and one pressure chamber group overlaps one discharge group in plan view.

  As shown in FIG. 2, the actuator units 17 each have a trapezoidal planar shape, and are arranged in a zigzag pattern in two rows on the upper surface 12x. As shown in FIG. 3, each actuator unit 17 is disposed on a trapezoidal region occupied by a pressure chamber group (discharge port group).

  The FPC 50 is provided for each actuator unit 17 and has wiring and terminals corresponding to the electrodes of the corresponding actuator unit 17. Each wiring is connected to the output terminal of the driver IC 57. Under the control of the controller 1p (see FIG. 1), the FPC 50 transmits data adjusted by the substrate 64 to the driver IC 57, and transmits each drive signal generated by the driver IC 57 to each electrode of the actuator unit 17. The drive signal is selectively applied to each electrode (individual electrode).

  Next, the configuration of the actuator unit 17 will be described with reference to FIGS. 6 and 7.

  As shown in FIG. 6A, the actuator unit 17 has a laminated body of three piezoelectric layers 17a, 17b, and 17c. The piezoelectric layers 17a, 17b, and 17c are all sheet-like members made of a lead zirconate titanate (PZT) ceramic having ferroelectricity. The piezoelectric layer 17a is polarized in the same direction as these stacking directions.

  The piezoelectric layers 17a, 17b, and 17c have the same size and shape (one actuator unit) as viewed from a direction orthogonal to the surface 17a1 (surface opposite to the piezoelectric layer 17b) of the piezoelectric layer 17a (that is, in plan view). 17 has a trapezoidal shape). That is, one actuator unit 17 is arranged across a number of pressure chambers 16 included in one pressure chamber group while straddling them, and the piezoelectric layer 17c includes all the pressure chambers 16 included in one pressure chamber group. It is sealed. In the present embodiment, the piezoelectric layers 17a, 17b, and 17c have substantially the same thickness.

  A large number of individual electrodes 18a are formed on the surface 17a1 at positions facing the pressure chambers 16, respectively. A common electrode 19 and a metal layer 20 are formed between the piezoelectric layer 17a and the lower piezoelectric layer 17b, and between the piezoelectric layer 17b and the lower piezoelectric layer 17c, respectively. No electrode is formed on the lower surface of the piezoelectric layer 17c. The common electrode 19 is formed over the entire top surface of the piezoelectric layer 17b, and the metal layer 20 is also formed over the entire top surface of the piezoelectric layer 17c. These electrodes 18a (excluding lands 18b and bumps 18d described later), the electrodes 19 and the metal layer 20 are both made of Au (gold) and have a thickness of about 1 μm. The metal layer 20 is connected to the common electrode 19 through a through hole at the corner of the trapezoidal actuator unit 17 in plan view. The metal layer 20 functions as a constant potential electrode common to all the pressure chambers 16 corresponding to one actuator unit 17 together with the common electrode 19.

  Similar to the pressure chambers 16, the individual electrodes 18a are arranged in a matrix so as to form a plurality of rows and a plurality of columns. As shown in FIG. 6B, each individual electrode 18a is composed of four parts: a main part 18a1, an extension part 18a2, a land 18b, and a bump 18d. The main portion 18a1 is slightly smaller in size than the pressure chamber 16. The main portion 18a1 is included in the outline of the pressure chamber 16 in a plan view, and has a substantially rhombus shape similar to the pressure chamber 16.

  The extending portion 18a2 extends to the outer region of the pressure chamber 16 along the surface 17a1. The extending portion 18a2 is a frame-like portion extending from one acute angle portion of the main portion 18a1, and as shown in FIG. 9A, the tip of the acute angle portion of the main portion 18a1 and the other three sides. It consists of and. Assuming a virtual line A that overlaps a long diagonal and a virtual line B that overlaps a short diagonal with respect to the main portion 18a1, the two sides 18a2x are in symmetrical positions across the virtual line A, and along the virtual line A It extends in a straight line. One side 18a2y is a linear portion parallel to the virtual line B and straddles the virtual line A. On the side opposite to the main portion 18a1 of the two sides 18a2x, one side 18a2y connects the ends of the two sides 18a2x. Through holes 18a2z are defined by these three sides 18a2x, 18a2y and the acute angle portion of the main portion 18a1. In other words, the extending portion 18a2 has the through hole 18a2z in a portion other than the outer edge (sides 18a2x, 18a2y).

  The land 18b is a conductive annular wall, and is disposed on the tip of the extending portion 18a2. As shown in FIG. 6B, the annular wall defines a central hole 18b1 of the land 18b. The entire land 18b does not face the pressure chamber 16 in plan view. The land 18b is formed of Ag—Pd (silver palladium), and has an outer diameter of about 130 μm and a height from the surface 17a1 of about 10 μm. The land 18b has the same height as a whole. Specifically, the thickness of the land 18b in the stacking direction is approximately 10 μm at a portion that does not overlap with the extending portion 18a2, and approximately 9 μm at a portion that overlaps with the extending portion 18a2 (the thickness obtained by subtracting the thickness of the individual electrode 18a from approximately 1 μm). It is).

  The bump 18d is a connection terminal with the FPC 50, and is accommodated in the hole 18b1 of the land 18b as shown in FIG. 6C. The bump 18d is made of Ag (silver) or Ag-Pd (silver palladium), and protrudes in a hemispherical shape from the tip surface of the land 18b. The height of the bump 18d from the surface 17a1 is approximately 40 to 50 μm. The bump 18d is electrically connected to the inner wall surface of the land 18b and the tip of the extended portion 18a2.

  The common electrode 19 and the metal layer 20 are electrodes common to all the pressure chambers 16 corresponding to one actuator unit 17, and are formed over the entire surface of the piezoelectric layers 17b and 17c, respectively. On the surface 17a1, in addition to the land 18b, a land 18c (see FIG. 3) for the common electrode 19 and the metal layer 20 made of the same material as the land 18b and having substantially the same shape and size as the land 18b is formed. The land 18c is disposed in the vicinity of the upper and lower bottoms of the trapezoid on the surface 17a1. The land 18c is connected to the terminal of the FPC 50 via the bump 18d, and is always held at the ground potential.

The piezoelectric layer 17a has an active portion at a portion sandwiched between the electrodes 18a and 19. The active part is displaced in at least one vibration mode (d _{31 in} this embodiment) selected from d ₃₁ , d ₃₃ , and d ₁₅ . The portions of the piezoelectric layers 17b and 17c that face the active portion are inactive portions. That is, the actuator unit 17 includes a unimorph type piezoelectric actuator for each pressure chamber 16. Each piezoelectric actuator is a laminated body of one active part and two inactive parts, and can be deformed independently. The actuator unit 17 applies a drive voltage from the FPC 50 to the individual electrode 18a, thereby changing the volume of the pressure chamber 16 corresponding to the piezoelectric actuator, and applying energy to the ink in the pressure chamber 16.

  In addition to the individual electrodes 18a and lands 18c, many dummy lands 18e are formed on the surface 17a1 at positions separated from the individual electrodes 18a (see FIG. 7). As shown in FIG. 7, the dummy land 18e is arranged at a position symmetrical to the land 18b with respect to one main portion 18a1. As shown in FIG. 7, individual electrodes 18a are alternately arranged at equal intervals along a short diagonal direction to form an electrode row, and a land 18b is sandwiched between two individual electrodes in the adjacent electrode row. Therefore, paying attention to one main portion 18a1, three lands 18b and three dummy lands 18e surround the main portion 18a1. In other words, the main portion 18a1 is arranged at the center of a hexagonal region where the three lands 18b and the three dummy lands 18e each form a vertex. The dummy land 18e is formed of the same material as that of the land 18b and has the same shape and size. However, the dummy land 18e is different from the land 18b in that no bump is disposed in the hole. That is, the dummy land 18e is not connected to the terminal of the FPC 50.

  Next, a method for manufacturing the head 10 will be described with reference to FIG.

  First, the flow path unit 12 and the actuator unit 17 excluding the bump 18d (hereinafter referred to as “actuator unit precursor”. However, in FIG. 7, for convenience of explanation, S2 is referred to as “actuator unit preparation”. And the reservoir unit 11 are manufactured separately (S1, S2, S3). These steps S1, S2, and S3 are performed independently, and either step may be performed first or in parallel.

  In S1, through holes are respectively formed in nine metal plates, and plates 12a to 12i are prepared. And these flow paths 12 are produced by laminating | stacking and bonding these plates 12a-12i mutually aligning. Bonding is performed by a method using an epoxy adhesive, but may be performed by a method that does not use an adhesive, such as metal bonding.

In S2, eight actuator unit precursors are produced.
First, three piezoelectric ceramic green sheets to be used as the piezoelectric layers 17a, 17b, and 17c are prepared. Of these, Au paste is screen-printed on the pattern of the common electrode 19 and the metal layer 20 on two green sheets (which will be the piezoelectric layers 17b and 17c), respectively. Then, a green sheet for the piezoelectric layer 17b is placed under the green sheet for the piezoelectric layer 17a without printing so as to sandwich the common electrode pattern of Au, and a green sheet for the piezoelectric layer 17c is sandwiched under the metal layer pattern of Au. Repeat. The laminate thus obtained is degreased and fired in the same manner as known ceramics. At this time, the three green sheets become the piezoelectric layers 17a, 17b, and 17c, and the Au paste becomes the common electrode 19 and the metal layer 20 (S21). After S21, Au paste is screen-printed on the surface 17a1 in the pattern of the individual electrodes 18a. And the said Au paste is baked and the main part 18a1 and the extension part 18a2 are formed in the surface 17a1 (S22: refer Fig.9 (a)). After S22, Ag-Pd paste is printed on the tip of each extension 18a2 to form a cylindrical land 18b protruding in a direction perpendicular to the surface 17a1 (S23: see FIG. 9B). At the same time, the common electrode 19, the land 18c for the metal layer 20, and the dummy land 18e are also formed at predetermined positions on the surface 17a1. Each land 18b, 18c, 18e is fired at a predetermined temperature. In this way, an actuator unit precursor is produced.

  In S3, through holes and recesses are respectively formed in the four metal plates, and the metal plates 11a to 11d are prepared. Then, the reservoir unit 11 is manufactured by laminating and joining these plates 11a to 11d while aligning each other. The joining method is the same as that of the flow path unit 12.

  Next, the eight actuator unit precursors fabricated in S2 are fixed to the flow path unit 12 fabricated in S1 while the main portion 18a1 faces the pressure chamber 16 in plan view (S4). Fixing is performed via an epoxy adhesive.

  After S4, a bump 18d is formed by applying a paste of Ag or Ag-Pd in the hole 18b1 of each land 18b, 18c (S5: see FIG. 9C). At this time, the bump 18d is formed using, for example, a mask that covers a region other than the region of the hole 18b1. In this way, the bump 18d is formed on the actuator unit precursor, whereby the actuator unit 17 is completed.

  After S5, the FPC 50 is connected to each actuator unit 17 (S6). Many terminals are formed near one end of the FPC 50. At this time, the vicinity of one end of the FPC 50 is placed on the actuator unit 17 and pressed, and the terminals and the corresponding bumps 18d are joined. At this time, the FPC 50 is opposed to the surface 17a1 through a gap of approximately 50 μm, except for the joint portion between each terminal and the lands 18b and 18c. Thereby, free deformation of each piezoelectric actuator of the actuator unit 17 is ensured.

  After S6, the reservoir unit 11 produced in S3 is fixed to the flow path unit 12 (S7). Thereafter, a step of electrically connecting the FPC 50 and the substrate 64 via the connector 64a, a step of assembling the side cover 65b and the top cover 65a so as to surround the reservoir unit 11 and the actuator unit 17 with the flow path unit 12 and the like. After that, the head 10 is completed.

  As described above, according to the head 10 and the manufacturing method thereof of the present embodiment, the bump 18d is accommodated in the hole 18b1 opened in the front end surface of the land 18b, thereby suppressing the displacement and spread of the bump 18d. Can do. As a result, uniform and reduced structural crosstalk is achieved.

  In addition, since the hole 18b1 is formed in the land 18b itself, it is not necessary to additionally provide another member in which the hole is formed, and the simplification of the configuration and the ease of manufacture are realized.

  A side wall (cylindrical side wall) defining the hole 18b1 of the land 18b surrounds the bump 18d over the entire circumference. As a result, the bump 18d is prevented from leaking out of the hole 18b1, and the spread of the bump 18d can be more reliably suppressed.

  The hole 18b1 penetrates to the bottom surface of the land 18b. That is, the land 18b is cylindrical. Thereby, the land 18b can be formed easily. Further, the bump 18d can be more securely accommodated in the hole 18b1 than in the case where the hole 18b1 does not penetrate to the bottom surface of the land 18b.

  The extending portion 18a2 has a through hole 18a2z in a portion other than the outer edge thereof. Thereby, the area of the extending portion 18a2 can be reduced, and the structural crosstalk can be more effectively suppressed.

  Since the dummy lands 18e having the same shape and size as the lands 18b are provided, the lands 18b and 18e have the same height. When the actuator unit 17 is fixed to the flow path unit 12, the individual lands 18b and 18e are individually connected via the lands 18b and 18e. A uniform pressure can be applied around the electrode 18a. Since the thickness of the adhesive is uniform regardless of location, the deformation performance of each piezoelectric actuator is also uniform. Further, the actuator unit 17 itself is hardly damaged.

  The bump 18d is not accommodated in the hole of the dummy land 18e. If the bump 18d is accommodated in the hole of the dummy land 18e, the wiring of the FPC 50 may be damaged when the land 18b and the terminal of the FPC 50 are joined. According to this embodiment, this problem is reduced. be able to.

  The height of the bump 18d from the surface 17a1 is equal to or higher than the height of the land 18b from the surface 17a1 (see FIG. 6C). Thereby, the land 18b and the terminal can be easily and reliably bonded via the bump 18d.

  When a crack reaching the common electrode 19 or the metal layer 20 is formed on the surface 17a1, if a bump 18d is disposed on the crack due to displacement or spread, a migration phenomenon (metal ions constituting the bump 18d) Due to the movement of the electrode 18a along the electric field), the individual electrode 18a and the common electrode 19 or the metal layer 20 may be short-circuited. This phenomenon is likely to occur when the bump 18d is made of a material containing Ag as in the present embodiment. However, according to the present embodiment, even when the bump 18d is made of a material containing Ag, the bump 18d is accommodated in the hole 18b1, so that the positional displacement and the spread of the bump 18d are suppressed. Can be prevented.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims.

The piezoelectric layer is not limited to extending over a plurality of pressure chambers, and may be provided individually for each pressure chamber.
The number of piezoelectric layers included in the actuator unit is arbitrary.

The land may be made of any conductive material other than Ag—Pd.
The shape and size of the land are arbitrary. For example, the planar shape may be a circle or a polygon such as an ellipse or a triangle. Further, the height of the land from the surface of the piezoelectric layer may not be uniform as a whole, and may be higher than the height of the bump.
The land may be disposed at a position facing the pressure chamber.
As long as the hole opens at the tip end surface of the land, the hole does not have to penetrate to the bottom surface of the land. That is, the land does not have to be cylindrical. For example, a recess that forms a hole may be formed on the tip surface of the columnar land. Further, the side wall defining the land hole may not surround the bump all around (for example, a part of the side wall is notched or the side wall has a semicircular arc shape in plan view). Good).
The position on the surface of the land for the common electrode is arbitrary, and the land for the common electrode is not limited to being formed on the surface. Moreover, the hole which accommodates a bump does not need to open in the front end surface of the land for common electrodes.

Bumps may be accommodated in the holes of the dummy lands.
The shape and size of the dummy land may not be the same as the land for the individual electrode.
Dummy lands may not be formed on the surface of the piezoelectric layer.

The shape, size, number, etc. of the individual electrodes and common electrodes are also arbitrary.
The number of through holes in the extension is not limited to 1, and may be 2 or more. The extending part may not have a through hole.

  In this embodiment, no conductive bump is disposed in the hole of the dummy land 18e, but a bump 18d may be disposed as in the lands 18b and 18c. At this time, the height of the bump from the surface 17a1 may be the same in each land 18b, 18c, 18e. By so doing, when the FPC 50 is fixed to the actuator unit 17, an equal pressure is applied around the individual electrodes 18a in the actuator unit 17 via the bumps. Thereby, concentration of pressure is relieved and damage to the actuator unit 17 can be suppressed.

The bump may be made of any conductive material (for example, Au) other than Ag or Ag—Pd.
The bump forming step (S5) may be performed after or before the fixing step (S4).
The common electrode 19 and the metal layer 20 may be made of any conductive material other than Au (for example, Ag or Ag—Pd).

  The liquid discharge head according to the present invention is not limited to a printer, and can be applied to a liquid discharge apparatus such as a facsimile or a copier. Further, the number of liquid discharge heads applied to the liquid discharge apparatus is not limited to four, and may be one or more. The liquid discharge head is not limited to the line type, and may be a serial type. Furthermore, the liquid discharge head according to the present invention may discharge a liquid other than ink.

1 Inkjet printer 10 Inkjet head (liquid ejection head)
12 Channel unit 14 Individual channel (liquid channel)
14a Discharge port 16 Pressure chamber 17 Actuator unit 17a, 17b Piezoelectric layer 17a1 Surface of piezoelectric layer 18a Individual electrode 18a1 Main part 18a2 Extension part 18a2z Through-hole 18b Land 18b1 hole 18d Bump 18e Dummy land

Claims (8)

A flow path unit in which a liquid flow path leading to a discharge port for discharging liquid through a pressure chamber whose volume changes is formed;
A piezoelectric layer, an individual electrode disposed on the surface of the piezoelectric layer facing the pressure chamber in a direction orthogonal to the surface, and connected to the individual electrode and protruding in a direction orthogonal to the surface An actuator unit that includes a conductive land, and changes a volume of the pressure chamber by applying a driving voltage to the individual electrode through the land.
The liquid discharge head according to claim 1, wherein a hole for accommodating a conductive bump that is bonded to the land and to which the driving voltage is supplied is opened at a front end surface of the land.   The liquid discharge head according to claim 1, wherein a side wall defining the hole of the land surrounds the bump all around.   The liquid discharge head according to claim 1, wherein the hole penetrates to a bottom surface of the land. The individual electrode has a main part facing the pressure chamber in a direction orthogonal to the surface, and an extension part extending from the main part along the surface and having the land formed thereon,
4. The liquid ejection head according to claim 1, wherein the extending portion has a through hole in a portion other than an outer edge thereof. 5.   5. The dummy land having the same shape and size as the land and not applied with the driving voltage is formed at a position separated from the individual electrode and the land on the surface. The liquid discharge head according to claim 1.   The liquid ejection head according to claim 5, wherein the bump is not accommodated in the hole of the dummy land.   The liquid ejection head according to claim 1, wherein a height of the bump from the surface is equal to or higher than a height of the land from the surface. A flow path unit production step for producing a flow path unit in which a liquid flow path is formed to reach a discharge port for discharging liquid through a pressure chamber whose volume changes;
The pressure chamber includes a piezoelectric layer, individual electrodes formed on the surface of the piezoelectric layer, and conductive lands connected to the individual electrodes, and a driving voltage is applied to the individual electrodes through the lands. An actuator unit manufacturing process for manufacturing an actuator unit that changes the volume of the individual electrode, the individual electrode forming process for forming the individual electrode on the surface, and a hole that protrudes in a direction orthogonal to the surface and that opens at the tip An actuator unit manufacturing step including a land forming step of forming the land,
A fixing step of fixing the actuator unit to the flow path unit while making the individual electrode face the pressure chamber in a direction orthogonal to the surface;
A bump forming step of forming a conductive bump in the hole;
A method of manufacturing a liquid discharge head, comprising:

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