JP5459182B2 - Liquid discharge head and manufacturing method thereof - Google Patents

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 liquid flow path (pressure chamber) corresponding to the individual electrode changes, and ink is ejected from the ejection port (nozzle opening). The individual electrode is joined to a terminal of a power supply member (FPC (Flexible Printed Circuit)) that applies a driving voltage to the individual electrode via a conductive bump.

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

  By the way, depending on the method of forming the bump, the plane size is likely to be larger than the design value. When the planar size of the bump is excessively enlarged, the active part region is enlarged, and the active part approaches another active part adjacent thereto, so that structural crosstalk (deformation of the active part affects the adjacent active part). Phenomenon) can be prominent.

  Therefore, it is conceivable to reduce the planar size of the bump in order to suppress structural crosstalk. However, in this case, the height of the bump is reduced, the bonding property between the bump and the terminal of the power supply member is deteriorated, and the power supply member is easily peeled off from the bump due to vibration or thermal shock that occurs when the head is used. That is, in this case, the reliability of electrical connection between the individual electrode and the power supply member is lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid discharge head capable of realizing both the suppression of an increase in the planar size of a bump and the securing of reliability of electrical bonding between an individual electrode and a power supply member, and a method for manufacturing the same. That is.

  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 to a discharge port for discharging liquid is formed, a piezoelectric layer, and the liquid flow path on the surface of the piezoelectric layer is provided. Including correspondingly formed individual electrodes and conductive bumps connected to the individual electrodes, a drive voltage is applied to the individual electrodes through the bumps to change the volume of the liquid channel. And the actuator unit fixed to the flow path unit, and the bump is composed of a plurality of portions stacked in an orthogonal direction orthogonal to the surface, and is closest to the surface among the plurality of portions. The first portion is larger in size as viewed from the orthogonal direction and has a higher hardness than the second portion that is farthest from the surface, and a liquid ejection head is provided.

  According to a second aspect of the present invention, a flow path unit manufacturing step of manufacturing a flow path unit in which a liquid flow path leading to a liquid discharge port is formed, a piezoelectric layer, and a surface of the piezoelectric layer are formed. An actuator unit manufacturing step of manufacturing an actuator unit that changes a volume of the corresponding liquid flow path by applying a driving voltage to the individual electrode, and the individual electrode is formed on the surface. An actuator unit manufacturing step including an individual electrode forming step to be formed; and a fixing step of fixing the actuator unit to the channel unit while making the individual electrode correspond to the liquid channel with respect to an orthogonal direction orthogonal to the surface. , After the fixing step, including a first portion closest to the surface and a second portion furthest away from the surface, in the orthogonal direction A bump forming step of forming a conductive bump composed of a plurality of layered portions connected to the individual electrode, the first step of forming the first portion, after the first step, A bump forming step including a second step of forming the second portion with a smaller size and lower hardness than the first portion with a conductive adhesive, and a curing step of curing the portion. A method for manufacturing a liquid discharge head is provided.

  According to the present invention, the bump is composed of a plurality of portions, and the first portion closest to the surface of the piezoelectric layer among the plurality of portions is viewed from the orthogonal direction rather than the second portion farthest from the surface. The size (planar size) is large and the hardness is high. As a result, the height of the entire bump can be secured while suppressing the planar size and obtaining good bondability. In other words, according to the present invention, it is possible to achieve both the suppression of the expansion of the planar size of the bump and the securing of the reliability of the electrical connection between the individual electrode and the power supply member.

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 a channel unit, an actuator unit, and FPC. (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 flowchart which shows the manufacturing method of an inkjet head. (A), (b), (c) is the top view and sectional drawing when a 1st process, a 2nd process, and an FPC fixing 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 pairs of 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 (Flexible Printed Circuit) 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. Inside the reservoir unit 11, an ink flow path including a reservoir 72 that temporarily stores the ink supplied from the cartridge 40 is formed. 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, and is open to the front end surface of the convex portion (that is, the joint 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 transmits data adjusted by the board 64 to the driver IC 57 under the control of the controller 1p (see FIG. 1), and each drive signal generated by the driver IC 57 is transmitted to the actuator IC 57. It transmits to each electrode of the unit 17.

  Next, the configuration of the actuator unit 17 and the FPC 50 will be described with reference to FIG.

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 sheets made of a lead zirconate titanate (PZT) ceramic having ferroelectricity, and have the same thickness.
The piezoelectric layers 17a, 17b, and 17c have the same size and shape when viewed from a direction orthogonal to the surface 17a1 (surface opposite to the piezoelectric layer 17b) of the piezoelectric layer 17a (hereinafter referred to as “plan view”). (Trapezoidal shape defining one actuator unit 17). One actuator unit 17 is arranged across the many pressure chambers 16 included in one pressure chamber group while straddling them, and the piezoelectric layer 17c seals the entire one pressure chamber group.
The piezoelectric layer 17a is polarized in the same direction as the stacking direction of the piezoelectric layers 17a to 17c.

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 and the metal layer 20 are formed over the entire upper surface of the piezoelectric layers 17b and 17c, respectively.
The individual electrode 18a, the common electrode 19, and the metal layer 20 are all made of Au (gold) and have a thickness of about 1 μm.

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 includes a main portion 18a1 and an extending portion 18a2.
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 from one acute angle portion of the main portion 18a1 to the outside of the pressure chamber 16 along the surface 17a1.

Lands 18b and bumps 18d are arranged in this order from the side closer to the surface 17a1 on the tip of the extending part 18a2.
Both the land 18b and the bump 18d do not face the pressure chamber 16 in plan view.

The land 18b has a cylindrical shape with a diameter D3 = approximately 130 μm and a height H3 = approximately 10 μm from the surface 17a1. The land 18b itself has a thickness (height) of about 9 μm, and the height H3 = about 10 μm together with the thickness of the extension 18a2 of about 1 μm.
The land 18b is made of a conductive material (Ag—Pd in this embodiment) such as Ag—Pd (silver palladium), Au (gold), or Ag (silver).

The bump 18d includes a first portion 18d1 and a second portion 18d2 that are stacked in a direction perpendicular to the surface 17a1. The first portion 18d1 and the second portion 18d2 are both hemispherical, but have different sizes.
The first portion 18d1 has a circular shape with a diameter D1 = approximately 160 μm in a plan view, and a height H1 from the surface 17a1 = approximately 30 μm.
The second portion 18d2 has a circular shape with a diameter D2 = approximately 120 μm in plan view, and a height H2 from the surface (upper surface) of the first portion 18d1 = approximately 10 μm. The second portion 18d2 is included in the outer contour of the first portion 18d1 (and the outer contour of the land 18b) in plan view.
Therefore, the bump 18d as a whole has a circular shape with a diameter D1 = approximately 160 μm in a plan view and a height (H1 + H2) from the surface 17a1 = approximately 40 μm.

The first portion 18d1 and the second portion 18d2 are both formed of a conductive adhesive containing Ag (silver) and an epoxy resin (resin component), but the content ratios of the resin components are different from each other. The second portion 18d2 contains more resin components than the first portion 18d1. Assuming that the whole is 100%, Ag = x%, epoxy resin = y% (x + y = 100), for example, the first portion 18d1 has x> 90 and y <10, and the second portion 18d2 has x = 80 to 90, y = 10 or more and 20 or less.
The first portion 18d1 has a higher hardness than the second portion 18d2.

  The common electrode 19 and the metal layer 20 are formed over the entire surface of the piezoelectric layers 17b and 17c, respectively, and function as electrodes common to all the pressure chambers 16 corresponding to one actuator unit 17. 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 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 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 that is formed of a laminate of one layer of active portions and two layers of inactive portions for each pressure chamber 16. Each piezoelectric actuator can be independently deformed.

  The FPC 50 includes a flexible substrate 51 made of an insulating material such as polyimide, wirings 52 and terminals 52d formed on the surface 51a of the substrate 51, and a coating layer 53 formed on the surface 51a.

  On the surface 51a, wirings 52 for the electrodes 18a and 19 of the actuator unit 17 and terminals 52d arranged at the tips of the wirings 52 are formed. Each wiring 52 is connected to the output terminal of the driver IC 57. Each of the terminals 52d is joined to the second portion 18d2 and is electrically connected to the bump 18d.

The covering layer 53 is made of an insulating material such as a fluorine-based resin, and is formed on substantially the entire surface 51a (portion excluding each terminal 52d). The covering layer 53 exposes each terminal 52d from the opening 53x on the surface 51a and covers the wiring 52.
The depth Hx of the opening 53x is smaller than the height H2 of the second portion 18d2. In plan view, the opening 53x is smaller than the terminal 52d and larger than the second portion 18d2.

  An adhesive layer 54 is provided between the FPC 50 and the actuator unit 17 so as to fill each opening 53x and surround each bump 18d. The adhesive layer 54 is made of a thermosetting material such as an epoxy resin, and extends from the front end surface (lower surface) of the terminal 52d to the surface 17a1, and mechanically bonds the FPC 50 and the actuator unit 17 together.

The FPC 50 transmits each drive signal generated by the driver IC 57 to each electrode of the actuator unit 17 via the wiring 52, the terminal 52d, and the bump 18d.
The actuator unit 17 changes the volume of the pressure chamber 16 to which the piezoelectric actuator corresponds by applying a driving voltage to the individual electrode 18a. As a result, energy is applied to the ink in the pressure chamber 16, and the ink is ejected from the ejection port 14a.

  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. The plates 12a to 12i may be joined by a method using an epoxy-based adhesive or by a method that does not use an adhesive such as metal joining.

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). After S22, an Ag-Pd paste is printed on the tip of each extension 18a2 to form a land 18b (S23). At the same time, the common electrode 19 and the land 18c for the metal layer 20 are also formed at predetermined positions on the surface 17a1. Each land 18b, 18c 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 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 method of joining the plates 11a to 11d 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. At this time, the actuator unit precursors are arranged in a zigzag pattern in two rows on the upper surface 12x of the flow path unit 12.

After S4, bumps 18d are formed on the lands 18b and 18c (S5).
In S5, first, a paste containing Ag and epoxy resin is applied to the tip (upper surface) of each land 18b, 18c to form a first portion 18d1 (S51: first step, see FIG. 8A). . Then, the 1st part 18d1 is hardened by heating to about 150 degreeC (S51h: 1st hardening process).
Then, a paste containing Ag and an epoxy resin (a paste containing more epoxy resin than the paste used in S51) is applied to the upper surface of each first portion 18d1 to form a second part 18d2 (S52: first Step (see FIG. 8B). At this time, the second portion 18d2 is formed so as to be smaller in size than the first portion 18d1 and included in the outer contour of the first portion 18d1 in plan view. Then, the 2nd part 18d2 is hardened by heating to about 150 degreeC (S52h: 2nd hardening process). The hardness after curing is lower in the second portion 18d2 than in the first portion 18d1.
In the first and second steps (S51, S52) based on the printing method, the first and second portions 18d1, 18d2 are formed using, for example, a mask that covers areas other than the regions of the portions 18d1, 18d2. .
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 fixed to each of the actuator units 17 (S6: FPC fixing step, see FIG. 8C).
In S6, the vicinity of one end of the FPC 50 is disposed on the actuator unit 17 while aligning the terminals 52d and the bumps 18d. Then, the FPC 50 is heated while being pressed against the actuator unit 17 in a state where the second portion 18d2 and the terminal 52d are in contact with each other and the adhesive layer 54 surrounds the periphery of the bump 18d. Harden. The adhesive layer 54 is an epoxy thermosetting resin. In the curing process, the adhesive layer 54 softens and becomes highly fluid, and spreads in the vicinity of the joint between the terminal 52d and the bump 18d. At this time, the adhesive layer 54 has an end on the FPC 50 side covering the vicinity of the opening 53x of the coating layer 53, and an end on the actuator unit 17 side reaches the surface 17a1 beyond the bump 18d. Thereby, the FPC 50 and the actuator unit 17 are mechanically joined, and each terminal 52d and each bump 18d are electrically connected.

  The thermosetting resin for the adhesive layer 54 may be applied on the bumps 18d by a printing method after the second curing step, or filled in the openings 53x of the coating layer 53 of the FPC 50. May be. When the FPC 50 and the actuator unit 17 are joined, the bump 18d penetrates the thermosetting resin layer and comes into contact with the terminal 52d.

  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 according to the present embodiment, the bump 18d is composed of a plurality of portions, and the first portion 18d1 closest to the surface 17a1 among the plurality of portions is replaced with the surface 17a1. It is assumed that the size (planar size) seen from the direction orthogonal to the surface 17a1 is larger and the hardness is higher than the second portion 18d2 farthest from the first portion 18d2 (see FIGS. 6A to 6C). As a result, the bump 18d as a whole can be secured to a height sufficient to obtain good bondability while suppressing the planar size. That is, according to the present embodiment, it is possible to realize both of the suppression of the expansion of the planar size of the bump 18d and the securing of the reliability of the electrical connection between the individual electrode 18a and the FPC 50.

In the FPC fixing step (S6), the low hardness second portion 18d2 is easily deformed. At this time, the second portion 18d2 is deformed, so that variations in height among the plurality of bumps 18d are suppressed, and the reliability of electrical connection between the actuator unit 17 and the FPC 50 is improved.
In the FPC fixing step (S6), the second portion 18d2 is deformed, so that the bonding area between the bump 18d and the terminal 52d is increased. Thereby, the joint strength between the actuator unit 17 and the FPC 50 is improved, and the reliability and durability of these electrical joints are increased.
Further, in the FPC fixing step (S6), when the second portion 18d2 is deformed, the pressure applied to the actuator unit 17 is absorbed by the deformation of the second portion 18d2, and the FPC 50 is moved to the actuator unit 17 with a relatively small pressure. Can be fixed to. Therefore, damage such as cracks in the piezoelectric layers 17a to 17c due to application of excessive pressure can be prevented.

  Vibrations and thermal shocks that occur when the head 10 is used are absorbed by the deformation of the low hardness second portion 18d2. Thereby, when the head 10 is used, the FPC 50 is not easily peeled off from the bump 18d, and the reliability and durability of electrical joining between the actuator unit 17 and the FPC 50 are improved.

  When the first portion 18d1 has a low hardness, the first portion 18d1 is easily deformed by pressure applied during the FPC fixing step (S6), vibration or thermal shock when the head 10 is used, and the planar size of the entire bump 18d It is difficult to ensure height accuracy. On the other hand, in the present embodiment, since the first portion 18d1 has a relatively high hardness, it is difficult to be deformed by pressure or the like, and the accuracy of the planar size and height of the entire bump 18d can be improved.

  The plurality of portions 18d1 and 18d2 constituting the bump 18d have a smaller planar size and lower hardness as a portion separated from the surface 17a1 in the direction orthogonal to the surface 17a1. As a result, it is possible to more effectively realize the suppression of the expansion of the planar size and the height of the bump 18d as a whole.

  Of the plurality of portions constituting the bump 18d, a portion excluding the first portion 18d1 (second portion 18d2) has an outer contour of another portion (first portion 18d1) closer to the surface 17a1 than the portion in plan view. It is included (see FIG. 6B). Thereby, it is possible to more effectively realize the suppression of the planar size and the securing of the height of the entire bump 18d.

  The actuator unit 17 includes a conductive land 18b interposed between the individual electrode 18a and the bump 18d and having a height from the surface 17a1 higher than that of the individual electrode 18a. Thereby, formation of bump 18d becomes easy. Further, in the fixing step (S4), the pressurizing jig is brought into contact with the land 18b without contacting the individual electrode 18a or the piezoelectric layer 17a (that is, the land 18b is used as the pressurizing point). it can.

An FPC 50 is used as a power supply member that applies a drive voltage to the individual electrode 18a. The coating layer 53 of the FPC 50 exposes each terminal 52d from the opening 53x. In the second portion 18d2, the height H2 from the surface of another portion (first portion 18d1) on which the second portion 18d2 is stacked is equal to or greater than the depth Hx of the opening 53x (see FIG. 6C).
With the above configuration, the FPC 50 faces the surface of the actuator unit 17 (particularly, the surface of the individual electrode 18a) through a gap in a region other than the connection portion with the bump 18d. Therefore, it is possible to reduce the problem that the FPC 50 impedes the free displacement of each piezoelectric actuator of the actuator unit 17. In addition, with the configuration as described above, the connection between the bump 18d and the terminal 52d is ensured, and the FPC 50 is not easily peeled off from the bump 18d.

The bump 18d is formed of a conductive adhesive containing silver and a resin component, and the second portion 18d2 contains more resin component than the first portion 18d1.
Thereby, the hardness of the second portion 18d2 is lower than that of the first portion 18d1 (in other words, the first portion 18d1 is higher in hardness than the second portion 18d2) before and after curing. Therefore, even if the second portion 18d2 is formed before the first portion 18d1 is cured, the first portion 18d1 is not easily deformed by an external pressure or the like, and the planar size is difficult to increase. Therefore, for example, S51h may be omitted, and the first and second portions 18d1 and 18d2 may be simultaneously cured in S52h, which increases the degree of freedom of the process.

In the bump forming step (S5), for each of the plurality of portions 18d1 and 18d2, other portions that are adjacent to the portion in the direction perpendicular to the surface 17a1 after the formation of the portion and that are separated from the surface 17a1 than the portion. A curing step is performed before the formation (in the above-described embodiment, a curing step (S51h) for curing the first portion 18d1 is performed before the second step (S52) for forming the second portion 18d2).
If other portions are formed before curing, the predetermined hardness is not exhibited, but the portion is deformed by pressure or the like, and the planar size is easily enlarged. On the other hand, according to the said structure, since another part is formed after hardening, predetermined | prescribed hardness is exhibited about the said part and it can prevent the expansion of plane size.

In the first step (S51), the first portion 18d1 is formed outside the pressure chamber 16 and at the tip of the extending portion 18a2 in plan view (see FIG. 6B).
For example, when the first portion 18d1 is formed at a position facing the pressure chamber 16 in a plan view, the piezoelectric layers 17a to 17c are likely to be damaged such as cracks by the pressure applied during the FPC fixing step (S6). On the other hand, according to the above configuration, since the point of action of the pressure applied during the FPC fixing step (S6) is outside the pressure chamber 16 in plan view, the piezoelectric layers 17a to 17c are unlikely to be damaged such as cracks.

  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 shape, size, number, etc. of the individual electrode, common electrode, and metal layer are arbitrary.
The individual electrode 18a, 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). Further, the metal layer 20 may be omitted.
The individual electrode may not be configured to include the main portion and the extension portion (for example, the extension portion may be omitted). When the individual electrode includes only the main part, bumps may be formed on the main part. At this time, from the viewpoint of preventing damage due to the applied pressure of the piezoelectric layers 17a to 17c, the bump is formed in a substantially rhombic pressure chamber at a position overlapping the acute angle portion in plan view. At this time, the land is also formed to overlap the acute angle portion of the pressure chamber.

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 an ellipse in addition to a circle, or a polygon such as a triangle. Further, the land is not limited to a columnar shape, and may be a cylindrical shape or the like. The land may not be higher than the individual electrode from the surface of the piezoelectric layer.
The position of the land for the common electrode on the surface of the piezoelectric layer is arbitrary, and the land for the common electrode is not limited to be formed on the surface of the piezoelectric layer (for example, it may be formed on the side surface of the piezoelectric layer).
The actuator unit may not include a land, and the individual electrode and the bump may be directly connected.

The bump may include a resin other than an epoxy resin as a resin component. Moreover, if the magnitude relationship of hardness is satisfy | filled, it is not limited to the 2nd part containing more resin components than a 1st part.
The bump is not limited to being formed of a conductive adhesive containing silver and a resin component, and may be formed of any conductive material (for example, Au).
Each part and the entire shape of the bump are arbitrary, and may be columnar. Further, the planar shape of each part and the entire bump may be, for example, a circle, an ellipse, or a polygon such as a triangle.
The position of the bump is not particularly limited, and may be a position facing the pressure chamber (particularly, an acute angle portion of the pressure chamber) in plan view.
The bump may further include not only the first and second portions but also one or more other portions interposed therebetween (that is, the bump may be composed of three or more portions). In the case of the portion, it is preferable that the portion separated from the surface of the piezoelectric layer has a smaller planar size and lower hardness. However, the portion interposed between the first portion and the second portion may have the same plane size and hardness as the first portion or the second portion, or may have a larger plane size and hardness than the first portion. May be. The parts other than the first part other than the first part may not be included in the outer contour of another part adjacent to the part and closer to the surface of the piezoelectric layer than the part in plan view.
The bump forming step (S5) may be performed before the fixing step (S4). Further, for example, the fixing step (S4) may be performed after the first portion is formed and cured and before the second portion is formed (between S51h and S52). In this case, the first portion receives pressure from the pressing jig in S4, but is difficult to deform due to high hardness.
In the bump forming step (S5), the plurality of portions are not limited to being sequentially cured from the first portion, and the plurality of portions may be cured at a time.

  In the bump forming step, the first portion 18d1 and the second portion 18d2 are subjected to curing treatment (heat treatment at 150 ° C.) in the first and second steps, but the second portion is at least in the second step. 18d2 may be in a semi-cured state (a state of insufficient curing). The hardness of the second portion 18d2 increases as the resin component cures. Therefore, the second portion 18d2 is stopped by a heat treatment of, for example, 70 ° C. to 80 ° C., and is in a semi-cured state that does not break the form during application. Then, when the adhesive layer 54 is cured, the second portion 18d2 that has been semi-cured may be cured. According to this configuration, the applied pressure can be lowered at the time of joining with the FPC 50, which contributes to preventing the actuator unit 17 from being damaged.

In the above-described embodiment, the opening 53x having the depth Hx smaller than the height H2 of the second portion 18d2 is provided in the FPC 50 as the power supply member (that is, H2> Hx), but H2 = Hx. May be. Alternatively, H2 <Hx may be satisfied. In particular, in the case of H2 <Hx, from the viewpoint of realizing reliable electrical connection between the second portion 18d2 and the terminal 52d, each portion in the range where the total thickness of some portions including the second portion is larger than Hx. Preferably has a size smaller than the opening 53x in plan view. Further, the covering layer 53 may be omitted.
A member other than the flat flexible substrate may be applied as the power supply member.

  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 12x top surface (one surface of channel unit)
14a Discharge port 16 Pressure chamber (liquid flow path)
17 Actuator unit 17a, 17b Piezoelectric layer 17a1 Surface of piezoelectric layer 18a Individual electrode 18a1 Main part 18a2 Extension part 18b Land 18d Bump 18d1 First part 18d2 Second part 50 FPC (feeding member, flat flexible substrate)
51 Substrate 52 Wiring 52d Terminal 53 Covering layer 53x Opening

Claims (16)

A flow path unit in which a liquid flow path leading to a discharge port for discharging liquid is formed;
A piezoelectric layer, an individual electrode formed on the surface of the piezoelectric layer corresponding to the liquid flow path, and a conductive bump connected to the individual electrode, and a driving voltage is applied to the individual electrode via the bump. An actuator unit fixed to the flow path unit that changes the volume of the liquid flow path when applied, and
The bump is composed of a plurality of portions stacked in an orthogonal direction orthogonal to the surface,
Of the plurality of portions, the first portion closest to the surface is larger in size as viewed from the orthogonal direction and has a higher hardness than the second portion most distant from the surface, Liquid discharge head.   2. The liquid ejection head according to claim 1, wherein the plurality of portions are smaller in size and lower in hardness as viewed from the orthogonal direction as the portion is separated from the surface with respect to the orthogonal direction.   The part excluding the first part is included in an outer contour of another part adjacent to the part and closer to the surface than the part when viewed from the orthogonal direction. Item 3. The liquid discharge head according to Item 2.   The liquid ejection head according to claim 1, wherein the plurality of portions includes the first portion and the second portion.   5. The actuator unit according to claim 1, wherein the actuator unit includes a conductive land interposed between the individual electrode and the bump and having a height higher than the surface of the individual electrode. The liquid discharge head according to claim 1. A flat flexible substrate fixed to the actuator unit and applying a driving voltage to the individual electrodes;
The flat flexible substrate includes a flexible substrate, terminals formed on the surface of the substrate, electrically connected to the bumps, wirings connected to the terminals, and the terminals exposed from the openings on the surface of the substrate. And an insulating coating layer covering the wiring,
The second portion connected to the terminal has a height from a surface of another portion where the second portion is laminated, which is equal to or greater than a depth of the opening in the orthogonal direction. The liquid discharge head according to any one of 1 to 5. The bump is formed of a conductive adhesive containing silver and a resin component,
The liquid ejection head according to claim 1, wherein the second portion contains more resin component than the first portion. A flow path unit manufacturing step of manufacturing a flow path unit in which a liquid flow path leading to a discharge port for discharging liquid is formed;
Actuator unit for producing an actuator unit including a piezoelectric layer and an individual electrode formed on the surface of the piezoelectric layer, and changing a volume of the corresponding liquid flow path when a driving voltage is applied to the individual electrode An actuator unit manufacturing step, including an individual electrode forming step of forming the individual electrode on the surface,
A fixing step of fixing the actuator unit to the flow channel unit while making the individual electrode correspond to the liquid flow channel with respect to an orthogonal direction orthogonal to the surface;
After the fixing step, conductive bumps composed of a plurality of parts stacked in the orthogonal direction including a first part closest to the surface and a second part farthest from the surface are formed on the individual electrodes. A bump forming step connected to the first portion, the first step forming the first portion, and after the first step, the size viewed from the orthogonal direction is smaller and the hardness is lower than the first portion A second step of forming the second portion with a conductive adhesive, and a bump forming step including a curing step of curing the portion;
A method of manufacturing a liquid discharge head, comprising:   In the bump forming step, for each of the plurality of portions, after the formation of the portion, and before the formation of another portion adjacent to the portion with respect to the orthogonal direction and separated from the surface than the portion, the curing step. The manufacturing method according to claim 8, wherein:   In the bump forming step, the plurality of portions are formed such that a portion separated from the surface in the orthogonal direction has a smaller size and a lower hardness as viewed from the orthogonal direction. The manufacturing method of Claim 8 or 9.   In the bump forming step, the part excluding the first part is included in an outer contour of another part adjacent to the part and closer to the surface than the part when viewed from the orthogonal direction. The manufacturing method according to claim 8, wherein the manufacturing method is formed.   12. The manufacturing method according to claim 8, wherein in the bump formation step, the plurality of portions including the first portion and the second portion are formed. The actuator unit manufacturing step includes a land forming step of forming a conductive land connected to the individual electrode and having a height higher than the surface than the individual electrode,
The manufacturing method according to claim 8, wherein, in the first step, the first portion is formed at a tip of the land in the orthogonal direction. A flexible substrate; a terminal formed on the surface of the substrate; a wiring connected to the terminal; and an insulating coating layer that exposes the terminal from the opening on the surface of the substrate and covers the wiring. A substrate-fixing step of fixing the flat flexible substrate to the actuator unit so that the terminal is electrically connected to the bump;
In the second step, the second portion connected to the terminal has a height from the surface of another portion where the second portion is laminated so as to be equal to or greater than the depth of the opening in the orthogonal direction. It forms, The manufacturing method as described in any one of Claims 8-13 characterized by the above-mentioned. In the flow path unit manufacturing step, as a part of the liquid flow path, a pressure chamber opened on one surface of the flow path unit and connected to the discharge port is formed,
In the individual electrode forming step, the individual electrode includes a main portion having a shape similar to the pressure chamber as viewed from the orthogonal direction, and an extending portion extending from the main portion to the outside of the pressure chamber. Form the
In the fixing step, the actuator unit is fixed to the one surface of the flow path unit so that the main part is included in the pressure chamber when viewed from the orthogonal direction,
In the first step, the first portion is formed outside the pressure chamber and at the tip of the extension portion when viewed from the orthogonal direction. The manufacturing method according to one item. In the first step of the bump forming step, the first portion of the bump is formed with a conductive adhesive containing silver and a resin component,
The said 2nd part is formed in the said 2nd process with the said conductive adhesive containing more said resin components than the said 1st part, The any one of Claims 8-15 characterized by the above-mentioned. Manufacturing method.

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