JP2011228606A - Mounting structure of substrate and droplet discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure of a flexible circuit board capable of preventing occurrence of failure in electrical junction, with reliable junction structure available in stable manner.SOLUTION: Relating to a mounting structure of a flexible circuit board, a flexible circuit board 27 is bent along the direction across the extending direction of a wiring 71, and under such state as the wirings 71 of a board banding part 27A positioned closer to a substrate tip end side than the bent point are arranged to face terminals 74 of a flow path formation substrate 22, the flow path formation substrate 22 and the flexible circuit board 27 are bonded together by NCP79. A dimension L1 in the extending direction of a junction part 75 contacting directly to the wiring 71, among the terminals 74 of the flow path formation substrate 22, is smaller than a dimension L2 in the extending direction of the wiring 71 at the substrate bending part 27A of the flexible circuit board 27.

Description

  The present invention relates to a substrate mounting structure and a droplet discharge head including the mounting structure.

  A droplet discharge method (inkjet method) has been proposed as one method for manufacturing a microdevice. This droplet discharge method is a method in which a fluid containing a material for forming a device is formed into droplets and discharged from a droplet discharge head. An ink jet type droplet discharge head includes a driving element such as a piezoelectric element that generates a pressure for discharging a fluid, and a driving signal is supplied to the driving element from an external circuit board. . Therefore, the droplet discharge head has a configuration in which a circuit board is mounted on the head body. For example, Patent Document 1 discloses a general technique for electrically connecting a terminal provided on an upper surface of a semiconductor chip and a terminal on a circuit board using a wire bonding technique. Patent Document 2 discloses a droplet discharge head in which a driving element (piezoelectric element) is connected to a driving device (driver IC) by wire bonding.

  In recent years, when microdevices are manufactured using the droplet discharge method, outer leads are used by using a flexible circuit board in which a wiring pattern that functions as outer leads is formed in order to meet the demand for further miniaturization of microdevices. A method of performing bonding (OLB: Outer Lead Bonding) connection has been proposed. According to this method, electrical connection between the drive element and the drive circuit unit (driver IC) can be performed without causing inconvenience such as an electrical short circuit between the wires (see Patent Document 3 below). ).

JP 2002-9235 A JP 2003-159800 A JP 2000-68989 A

  By the way, as a method of mounting a flexible circuit board on an element substrate on which a driving element such as a piezoelectric element is formed, an anisotropic conductive adhesive (Anisotropic Conductive Paste, Hereinafter, a method of electrical connection via ACP) is known. By using ACP containing fine conductive particles in a resin, each terminal and each wiring can be electrically connected without causing an electrical short circuit between adjacent terminals. However, as the size of the droplet discharge head is reduced and the resolution is increased, the distance between adjacent drive elements is reduced as the distance between adjacent drive elements is reduced. Even if ACP is used, an electrical short circuit occurs between adjacent terminals. There was a risk of occurrence. Therefore, a flexible circuit board mounting method using a non-conductive adhesive (hereinafter abbreviated as NCP) instead of ACP has been studied.

  In the mounting structure using the ACP, conductive particles are interposed between each terminal of the driving element and each wiring of the flexible circuit board, whereas in the mounting structure using the NCP, the terminal of the driving element is flexible. The circuit board wiring is directly crimped to achieve electrical connection, and both are fixed with a resin adhesive. Therefore, in the mounting process, after applying NCP on the terminals of the element substrate, a load is applied using a crimping tool with the flexible circuit board placed thereon, and NCP is applied from the joint surface between each terminal and each wiring. It is necessary to crimp each terminal and each wiring while eliminating them. Thereby, each terminal and each wiring are joined in a direct contact state, and each terminal and each wiring are fixed around the joint surface by the excluded NCP.

  However, in the conventional mounting process, the pressure applied to the bonding surface by the crimping tool may be insufficient, and NCP (insulating resin) tends to remain on the bonding surface, which may cause a bonding failure. Therefore, there is a problem that it is difficult to stably manufacture a product with high reliability of electrical connection, particularly when a flexible circuit board having a fine pattern is mounted.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a substrate mounting structure that can prevent the occurrence of defective electrical bonding and stably obtain a highly reliable bonding structure. To do. It is another object of the present invention to provide a high-quality liquid droplet ejection head by providing such a mounting structure.

  To achieve the above object, the substrate mounting structure of the present invention includes a first substrate having a first surface and a terminal extending on the first surface and extending in a first direction, and the first substrate. A second substrate having an opposing surface facing the surface and extending in the first direction provided between the opposing surface, the first surface and the opposing surface, and the terminal A non-conductive adhesive for adhering the first substrate and the second substrate in a state in which the wiring is opposed and in direct contact with the wiring, and the first portion of the joint portion in direct contact with the wiring in the terminal The length in the direction is shorter than the length in the first direction of the wiring on the facing surface.

  In the conventional mounting structure, the dimension in the extending direction at the joint portion between the terminal and the wiring extending in the predetermined direction is the same, and the terminal and the wiring are joined in a state in which they are in contact with each other in the extending direction. It had been. Therefore, even when a load is applied to the joint using a crimping tool or the like in the mounting process, the pressure is dispersed due to the large joint area between the terminal and the wiring, and a sufficient load may not be applied uniformly to the entire joint surface. there were. In addition, since the joint surface between the terminal and the wiring is large, the NCP insulating resin may not be completely eliminated from the joint surface. Due to these factors, there is a risk of poor bonding.

  On the other hand, according to the mounting structure of the substrate of the present invention, the length in the first direction of the joint portion in direct contact with the wiring among the terminals of the first substrate is the first of the wiring on the opposing surface of the second substrate. Since it is shorter than the length in one direction, even if the size of the facing surface of the second substrate is the same as the conventional one, the junction area between the terminal and the wiring, substantially the junction and the wiring (directly in contact with the wiring) The bonding area is smaller than before. For this reason, even when the same load as before is applied using a crimping tool or the like, the load is concentrated on the joint portion because the joint area is small, and the pressure applied per unit area becomes larger than before. Therefore, the bonding portion and the wiring are sufficiently crimped.

  Furthermore, according to the mounting structure of the present invention, the joint portion on the first substrate side does not face the entire wiring on the second substrate side, and the portion between the first substrate and the second substrate is not present in the portion where the joint portion does not exist. A minute space (gap) corresponding to the thickness of the joint portion is generated between them. As a result, the NCP insulating resin is removed from the bonding surface and remains in this space, and the bonding portion and the wiring are stably fixed. In this manner, it is possible to provide a substrate mounting structure that can prevent the occurrence of defective electrical bonding and stably obtain a highly reliable bonding structure.

In the mounting structure of the present invention, the terminal includes the joint, and a wiring bent portion that is electrically connected to the joint and extends in a second direction intersecting the first direction. You may do it.
According to this configuration, since the wiring bent portion is provided, the length of the joint portion in the first direction is shortened and a space for discharging NCP is formed. Fully obtained. In addition, this configuration can be easily realized only by changing the design of the wiring pattern from the wiring on the first substrate to the terminal.

When the above configuration is adopted, it is preferable that the wiring bent portion extends in a direction obliquely intersecting the first direction.
According to this configuration, a sufficient space between the terminals can be secured, and occurrence of a short circuit between the terminals can be prevented.

Alternatively, in the mounting structure of the present invention, the terminal is provided on the second surface different from the first surface of the first substrate and the bonding portion provided on the first surface of the first substrate. And a relay conducting portion formed in a through hole that penetrates a layer between the first surface and the second surface, and the joint portion and the conductive portion are interposed via the relay conducting portion. Alternatively, an electrically connected configuration may be employed.
According to this configuration, since the conductive portion is provided on the second surface different from the first surface provided with the joint portion, the joint portion is isolated on the first surface. As the dimension in the current direction becomes smaller, a space for discharging NCP is formed, and the functions and effects of the present invention can be sufficiently obtained. In addition, although a wiring multilayer structure is required on the first substrate, the above-mentioned wiring bent portion is not necessary, so that the wiring and the joint can be formed on the same straight line when viewed from the normal direction of the substrate. Wiring routing design becomes easy.

In the mounting structure of the present invention, it is desirable that the joint surface of the joint portion and the joint surface of the wiring are flat surfaces.
According to this configuration, the joint portion and the wiring can be reliably crimped while reducing the dimension of the joint portion in the first direction.

A droplet discharge head according to the present invention includes a terminal provided on a first surface and extending in a first direction, and a drive element that is electrically connected to the terminal and generates a pressure for discharging a droplet. A first substrate formed, a wiring provided on a facing surface facing the first surface and extending in the first direction, and a driving circuit unit electrically connected to the wiring and driving the driving element, Adhering the first substrate and the second substrate in a state of being provided between the provided second substrate and the first surface and the facing surface, the terminal and the wiring being opposed and in direct contact with each other A non-conductive adhesive, and a length of the joint in the terminal in direct contact with the wiring is shorter than a length of the wiring in the first direction on the facing surface. Features.
According to this configuration, since the length in the first direction of the joint portion in direct contact with the wiring is shorter than the length in the first direction of the wiring on the facing surface of the second substrate, the dimension of the facing surface of the second substrate is Even if it is the same as the prior art, the junction area between the terminal and the wiring, and substantially the junction area between the joint and the wiring (which is in direct contact with the wiring) is smaller than the conventional one. For this reason, even when the same load as before is applied using a crimping tool or the like, the load is concentrated on the joint portion because the joint area is small, and the pressure applied per unit area becomes larger than before. Therefore, the bonding portion and the wiring are sufficiently crimped. Thereby, it is possible to realize a high-quality liquid droplet ejection head with high reliability of electrical connection.

  A droplet discharge head according to the present invention includes a drive element for generating a pressure for discharging a droplet, and a plurality of terminals extending in a predetermined extending direction. A second substrate made of a flexible circuit board having a driving circuit section to be driven and a plurality of wirings extending in the same direction as the extending direction is mounted, and each terminal and each wiring are electrically joined. As a result, a droplet discharge head in which the drive element and the drive circuit unit are electrically connected, wherein the second substrate is bent in a direction intersecting the extending direction, The first substrate and the second substrate are non-conductively bonded in a state where the respective wirings of the substrate bent portion, which is closer to the tip of the substrate than the bent portion, and the respective terminals of the first substrate are arranged to face each other. Of the terminals of the first substrate, bonded by a material The extending direction of the dimension of the joint which contacts the wiring and directly, characterized in that the smaller than the extending direction of the dimension of the wiring in the board bent portion of the second substrate.

  According to the droplet discharge head of the present invention, among the terminals of the first substrate, the dimension in the extending direction of the joint portion that is in direct contact with the wiring is such that the extending direction of the wiring in the substrate bent portion of the second substrate. Therefore, even if the dimensions of the bent portion of the flexible circuit board are the same as the conventional size, the junction area between the terminal and the wiring, substantially (the direct contact with the wiring) The bonding area is smaller than before. For this reason, even when the same load as before is applied using a crimping tool or the like, the load is concentrated on the joint portion because the joint area is small, and the pressure applied per unit area becomes larger than before. Therefore, the bonding portion and the wiring are sufficiently crimped. Thereby, it is possible to realize a high-quality liquid droplet ejection head with high reliability of electrical connection.

1 is an external perspective view showing a configuration of a droplet discharge head according to a first embodiment of the present invention. It is a disassembled perspective view of a droplet discharge head. It is the perspective view seen from the nozzle opening side in the state where a droplet discharge head was partially broken. It is AA arrow sectional drawing of FIG. It is sectional drawing which expands and shows the principal part of an OLB connection part. It is a top view of a terminal part. It is a top view which shows the state which piled up the flexible circuit board on the terminal part. It is a top view of the terminal part in the mounting structure of the flexible circuit board concerning 2nd Embodiment of this invention. It is a top view which shows the state which piled up the flexible circuit board on the terminal part. It is sectional drawing in the mounting structure of the flexible circuit board based on 3rd Embodiment of this invention. It is a top view of a terminal part. It is a top view which shows the state which piled up the flexible circuit board on the terminal part. It is sectional drawing in the mounting structure of the flexible circuit board which concerns on 4th Embodiment of this invention. It is a top view of a terminal part. It is a top view which shows the state which piled up the flexible circuit board on the terminal part. It is sectional drawing in the mounting structure of the conventional flexible circuit board. It is a top view of a terminal part. It is a top view which shows the state which piled up the flexible circuit board on the terminal part.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

[First Embodiment]
A first embodiment of a mounting structure for a droplet discharge head and a flexible circuit board according to the present invention will be described with reference to FIGS.
FIG. 1 is an external perspective view showing a configuration of a droplet discharge head according to the present embodiment. FIG. 2 is an exploded perspective view of the droplet discharge head. FIG. 3 is a perspective view of the droplet discharge head as viewed from the nozzle opening side in a partially broken state. 4 is a cross-sectional view taken along line AA in FIG. FIG. 5 is an enlarged cross-sectional view showing the connection portion of the flexible circuit board. FIG. 6 is a plan view of the terminal portion of the flow path forming substrate. FIG. 7 is a plan view showing a state in which the flexible circuit board is overlaid on the terminal portion.

As shown in FIGS. 1 to 4, the liquid droplet ejection head 1 ejects functional liquid droplets, and includes a nozzle substrate 21 in which nozzle openings for ejecting liquid droplets are formed, and the nozzle substrate 21. A flow path forming substrate 22 (first substrate) that is provided on the upper surface and forms a flow path through which droplets flow, and a piezoelectric element 23 (driving element: see FIG. 4) provided on the upper surface of the flow path forming substrate 22 is driven. Displaceable diaphragm 24, reservoir forming substrate 25 for forming reservoir 37 (see FIG. 4) provided on the upper surface of diaphragm 24, case member 101 provided on the upper surface side of reservoir forming substrate 25, and 2 The main body 1A includes a pair of flexible circuit boards 27 (second boards) on which two driver ICs 26 (26A, 26B: drive circuit units) are mounted.
In the present embodiment, the droplet discharge head 1 is configured by one substrate 1A. However, the droplet discharge head may be configured by unitizing a plurality of substrates 1A.

    The flexible circuit board 27 electrically connects the driver ICs 26A and 26B to the piezoelectric element 23 described later, and is mounted in a state where the ends are bent so that the active surfaces of the driver ICs 26A and 26B face each other. Has been.

    Case member 101 is made of stainless steel. The case member 101 is used as an attachment member when the droplet discharge head 1 is mounted on a droplet discharge device.

    An opening 102 formed along the Y-axis direction is formed at the center of the case member 101 in the X-axis direction. As shown in FIG. 2, the opening 102 has a size including at least the opening regions of the two openings 60 formed in the reservoir forming substrate 25. Since the flexible circuit board 27 is inserted into the opening 102, a holding region 103 of the driver IC 26 is formed in a predetermined shape at a predetermined position.

As shown in FIG. 3, the nozzle substrate 21 is made of, for example, stainless steel or glass ceramics. The nozzle substrate 21 is a through-hole penetrating the nozzle substrate 21, and a plurality of nozzle openings 31 for discharging functional liquid droplets are formed. ing. A plurality of nozzle openings 31 formed side by side in the Y-axis direction constitute a nozzle opening group 310. In the present embodiment, a total of four nozzle aperture groups 310 are provided, two in the X-axis direction and two in the Y-axis direction.
In FIG. 3, each nozzle opening group 310 is shown as having six nozzle openings 31, but actually, for example, about 720 nozzle openings 31 are formed.

    The flow path forming substrate 22 is formed of, for example, a rigid silicon single crystal, and the plurality of partition walls 35 are formed by anisotropically etching the silicon single crystal substrate that is the base material of the flow path forming substrate 22. ing. Further, the nozzle substrate 21 is fixed to the lower surface of the flow path forming substrate 22 via, for example, an adhesive or a heat-welded film, while the upper surface (the lower surface side in FIG. 3) of the flow path forming substrate 22 is vibrated. A plate 24 is provided.

    The pressure generation chamber 36 is a portion where the functional liquid discharged from the nozzle opening 31 is disposed. As shown in FIG. 4, the flow path forming substrate 22 having a plurality of partition walls 35, the nozzle substrate 21, and the vibration A space surrounded by the plate 24 is formed. A plurality of pressure generation chambers 36 are formed side by side in the Y-axis direction so as to correspond to the plurality of nozzle openings 31 constituting each of the four nozzle opening groups 310. A plurality of pressure generation chambers 360 is configured by a plurality of pressure generation chambers 36 corresponding to each nozzle opening group 310.

    One end portions of the plurality of pressure generation chambers 36 constituting each pressure generation chamber group 360 are communicated with each other by a communication portion 39 via a supply path 38 constituting a part of the reservoir 37.

    The diaphragm 24 is disposed between the flow path forming substrate 22 and the reservoir forming substrate 25, and is provided on the upper surface of the elastic film 41 and an elastic film 41 provided to cover the upper surface of the flow path forming substrate 22. And a lower electrode film 42. The elastic film 41 is made of, for example, silicon dioxide having a thickness of about 1 to 2 μm, and the lower electrode film 42 is made of, for example, platinum having a thickness of about 0.2 μm. In the present embodiment, the lower electrode film 42 is an electrode shared by the plurality of piezoelectric elements 23.

    The piezoelectric element 23 is a driving element for displacing the diaphragm 24, and includes a piezoelectric film 45 provided on the upper surface of the lower electrode film 42, and an upper electrode film 46 provided on the upper surface of the piezoelectric film 45. And a lead electrode 47 that is a lead-out wiring for the upper electrode film 46.

    The piezoelectric film 45 is made of, for example, a metal oxide having a thickness of about 1 μm. The upper electrode film 46 is made of, for example, platinum having a thickness of about 0.1 μm, and the lead electrode 47 is made of, for example, gold having a thickness of about 0.1 μm. An insulating film (not shown) is provided between the lead electrode 47 and the lower electrode film 42.

    A plurality of piezoelectric elements 23 are provided so as to correspond to each of the plurality of nozzle openings 31 and the pressure generation chamber 36. That is, the piezoelectric element 23 is provided for each nozzle opening 31 (for each pressure generation chamber 36). As described above, the lower electrode film 42 functions as a common electrode for the plurality of piezoelectric elements 23, and the upper electrode film 46 and the lead electrode 47 function as individual electrodes for the plurality of piezoelectric elements 23.

    In addition, a piezoelectric element group 230 is formed by a plurality of piezoelectric elements 23 provided side by side in the Y-axis direction so as to correspond to the nozzle openings 31 constituting the nozzle opening group 310. Here, four piezoelectric element groups 230 are provided corresponding to the nozzle opening groups 310, respectively. Of these four piezoelectric element groups 230, one corresponding to the driver IC 26A is referred to as a piezoelectric element group 230A, and one corresponding to the driver IC 26B is referred to as a piezoelectric element group 230B. The piezoelectric element group 230A and the piezoelectric element group 230B are arranged in parallel while being close to each other.

    The piezoelectric element 23 may include a lower electrode film 42 in addition to the piezoelectric film 45, the upper electrode film 46 and the lead electrode 47. That is, the lower electrode film 42 in the present embodiment may be configured to have both the function as the piezoelectric element 23 and the function as the diaphragm 24. In this embodiment, the diaphragm 24 is constituted by the elastic film 41 and the lower electrode film 42. However, the elastic film 41 may be omitted and only the lower electrode film 42 may have the function of the elastic film 41. .

    Further, the reservoir forming substrate 25 is formed of a rigid body, and it is preferable to use a material substantially the same as the coefficient of thermal expansion of the channel forming substrate 22 such as glass or ceramic material. In this embodiment, the channel forming substrate 22 is used. A silicon single crystal substrate of the same material is used.

    As shown in FIG. 4, reservoir portions 51 corresponding to the respective communicating portions 39 are formed on the reservoir forming substrate 25 so as to extend in the Y-axis direction. The reservoir portion 51 and the communication portion 39 described above constitute a reservoir 37. In addition, the reservoir forming substrate 25 is formed with an introduction path 52 that is connected to the side wall of each communication portion 39 and introduces the functional liquid into each communication portion 39.

    A groove-shaped opening 60 extending in the Y-axis direction is formed at the center of the reservoir forming substrate 25 in the X-axis direction. In the opening 60, a part of the flow path forming substrate 22 is exposed. Sealing portions 61 </ b> A and 61 </ b> B for sealing each piezoelectric element group 230 with the diaphragm 24 are formed in the region outside the opening 60 in the X-axis direction.

Piezoelectric elements that can seal the space in the reservoir forming substrate 25 in a state facing the respective piezoelectric element groups 230 in a state in which a space that does not hinder the driving of the plurality of piezoelectric elements 23 constituting these is secured. A holding part 62 is formed. The piezoelectric element holding part 62 is formed corresponding to each of the sealing parts 61 </ b> A and 61 </ b> B, and has a size that covers each piezoelectric element group 230.
Of the piezoelectric elements 23, at least the piezoelectric film 45 is sealed in the piezoelectric element holding portion 62.

    As described above, the reservoir forming substrate 25 has a function as a sealing member for blocking the piezoelectric element 23 from the external environment and sealing the piezoelectric element 23. By sealing the piezoelectric element 23 with the reservoir forming substrate 25, it is possible to prevent the piezoelectric element 23 from being damaged by an external environment such as moisture.

In addition, among the piezoelectric elements 23 sealed by the sealing portion 61 (piezoelectric element holding portion 62), one end portion of the lead electrode 47 extends to the outside of the sealing portion 61. It is disposed on the exposed flow path forming substrate 22.
A portion of the lead electrode corresponding to an end connected to the flexible circuit board 27 and exposed at the opening 60 of the flow path forming substrate 22 is hereinafter referred to as a “terminal”.

    A compliance substrate 53 is bonded to the upper surface of the reservoir forming substrate 25. The compliance substrate 53 has a sealing film 54 and a fixing plate 55. The sealing film 54 is formed of a material having low rigidity and flexibility, such as a polyphenylene sulfide film having a thickness of about 6 μm. The upper portion of the reservoir 51 is sealed with the sealing film 54.

    The fixing plate 55 is formed of a hard material such as a metal such as stainless steel having a thickness of about 30 μm. A region of the fixed plate 55 corresponding to the reservoir 51 is an opening 56 that is completely removed in the thickness direction. Therefore, the upper part of the reservoir 51 is sealed only by the flexible sealing film 54, and thus is a flexible part 57 that can be deformed by a change in internal pressure. A case member 101 is provided on the compliance substrate 53.

    In addition, the compliance substrate 53 and the case member 101 outside the reservoir unit 51 are provided with a functional liquid introduction port 58 that communicates with the introduction path 52 and supplies the functional liquid to the reservoir unit 51. Normally, when the functional liquid is supplied from the functional liquid introduction port 58 to the reservoir section 51, a pressure change occurs in the reservoir section 51 due to, for example, the flow of the functional liquid when the piezoelectric element 23 is driven or the surrounding heat. However, as described above, since the upper portion of the reservoir portion 51 is the flexible portion 57 sealed only by the sealing film 54, the flexible portion 57 is bent and deformed to absorb the pressure change. Therefore, the inside of the reservoir 51 is maintained at a constant pressure. The other portions are held at a sufficient strength by the fixing plate 55. The case member 101 is provided in a non-contact state with the flexible portion 57 so as not to impair the deformation of the flexible portion 57.

    As shown in FIG. 4, the flexible circuit board 27 is mounted in a state where the connection part 27 </ b> A is inserted into the opening part 102 provided in the case member 101 and the opening part 60 formed in the reservoir forming board 25. Has been.

Hereinafter, the mounting structure of the flexible circuit board of the present embodiment will be described with reference to FIGS.
As shown in FIGS. 5 to 7, the flexible circuit board 27 is formed of a base material 70 and a plurality of wirings 71 formed on one surface of the base material 70. The plurality of wirings 71 are formed so as to be separated from each other at a predetermined interval and to extend in parallel to each other in a predetermined extending direction (first direction). The flexible circuit board 27 is bent in a direction substantially orthogonal to the extending direction of the wiring 71 with the surface on which the plurality of wirings 71 are formed facing outside. Here, the portion of the flexible circuit board 27 that is closer to the tip of the substrate than the bent portion is referred to as a substrate bent portion 27A. In a state in which each wiring 71 of the substrate bent portion 27A and each terminal 74 of the lead electrode 47 on the flow path forming substrate 22 are arranged to face each other, the flow path forming substrate 22 and the flexible circuit board 27 are non-conductive adhesive. 79 (NCP).
In addition, the surface facing the terminal 74 of the substrate bent portion 27A corresponds to the “facing surface” in the claims.

  As shown in FIG. 5, the terminal 74 includes a junction 75 formed on an insulating film (not shown) on the upper surface (first surface) of the flow path forming substrate 22, and an insulating film (as shown in FIG. And a wiring bent portion 76 extending in a direction in which the extension line D of the lead electrode 47 (wiring) formed on the first surface is bent in the first surface. The plurality of terminals 74 are formed so as to be spaced apart from each other at a predetermined interval and to extend in parallel to each other in a predetermined extending direction (first direction). The joint portion 75 is a portion that directly contacts the wiring 71 of the flexible circuit board 27 and is a portion that mainly contributes to electrical connection. The wiring bent portion 76 extends in a direction that obliquely intersects the extension line D of the lead electrode 47 (wiring). The angle θ formed by the extension line D of the lead electrode 47 (wiring) and the extending direction E of the wiring bent portion 76 is preferably about 20 ° to 30 °. If the angle is set to such an angle, the interval between the adjacent wiring bent portions 76 can be ensured to be substantially the same as the interval between the adjacent joint portions 75, so that a short circuit between the adjacent wiring bent portions 76 can be prevented. Can be prevented.

  Further, as shown in FIG. 6, the joint portion 75 is formed integrally with the wiring bent portion 76, and at a position deviated from the extension line D of the lead electrode 47 (wiring) (from the extension line D in FIG. 6). Is also located on the lower side. With the above configuration, when the wiring 71 of the flexible circuit board 27 is overlaid on the terminal 74 of the flow path forming substrate 22, the result is as shown in FIG. The portion overlaps the wiring 71, and a part of the wiring bent portion 76 and the extended portion 47 a of the lead electrode 47 (wiring) are not overlapped with the wiring 71.

  FIG. 5 shows a cross-sectional structure in which the central axis of the wiring 71 of the flexible circuit board 27 in FIG. 7 is a cutting line A-A ′. As shown in FIG. 5, the dimension L <b> 1 in the extending direction of the joint portion 75 is smaller than the dimension L <b> 2 in the extending direction of the wiring 71 in the board bending portion 27 </ b> A of the flexible circuit board 27. The dimension L1 is desirably about 1/2 to 2/3 of the dimension L2. When the dimension L1 is smaller than ½ of the dimension L2, the junction area becomes too small, and the reliability of electrical connection is lowered. When the dimension L1 is larger than 2/3 of the dimension L2, the effect of the present invention that improves the pressure-bonding performance by concentrating the load on a small joining area cannot be obtained.

  Further, the joint surface of the joint portion 75 and the joint surface of the wiring 71 are both flat. As a result, the junction 75 and the wiring 71 can be securely bonded to each other after the dimension in the extending direction of the junction 75 is reduced.

Here, it compares with the mounting structure of the conventional flexible circuit board.
FIG. 16 is a cross-sectional view of a conventional mounting structure. FIG. 17 is a plan view of a conventional terminal portion. FIG. 18 is a plan view showing a state in which a flexible circuit board is superimposed on a conventional terminal portion.
As shown in FIG. 17, the conventional terminal portion has a plurality of terminals 110 extending from the lead electrode as they are in parallel to each other. Therefore, when the wiring 71 of the flexible circuit board 27 is overlaid on the terminal 110, the entire terminal 110 overlaps the wiring 71 as shown in FIGS. Further, as shown in FIG. 16, the flow path forming substrate 22 and the flexible circuit substrate 27 are fixed in a state where the NCP 79 remains around the end portion of the flexible circuit substrate 27 and the bent portion.

  In the conventional mounting structure, since the dimension in the extending direction of the joint portion between the terminal 110 and the wiring 71 is the same and the terminal 110 and the wiring 71 are in contact with each other, a crimping tool or the like is used in the mounting process. Even when a load is applied to the joint portion, the joint area between the terminal 110 and the wiring 71 is large, so that the pressure is dispersed, and a sufficient load may not be uniformly applied to the entire joint surface. In addition, since the joint surface between the terminal 110 and the wiring 71 is large, the NCP79 insulating resin may not be completely removed from the joint surface. Due to these factors, there is a risk of poor bonding.

  On the other hand, according to the mounting structure of the flexible circuit board 27 of the present embodiment, the dimension L1 in the extending direction of the joining portion 75 that is in direct contact with the wiring 71 among the terminals 74 is the wiring at the board bent portion 27A. Since the dimension of the bent portion 27A of the flexible circuit board 27 is the same as the conventional size because the dimension is smaller than the dimension L2 in the extending direction of 71, the junction area between the terminal 74 and the wiring 71, substantially the junction. The junction area between 75 and the wiring 71 is smaller than the conventional one. For this reason, even when the same load as before is applied using a crimping tool or the like, the load is concentrated on the joining portion 75 as the joining area is small, and the pressure applied per unit area becomes larger than before. Therefore, the joining portion 75 and the wiring 71 are sufficiently crimped.

  Furthermore, according to the mounting structure of the present embodiment, the joint 75 on the flow path forming substrate 22 side does not face the entire wiring 71 on the flexible circuit board 27 side. A minute space (gap) corresponding to the thickness of the joint 75 (for example, about several μm) is formed between the formation substrate 22 and the flexible circuit board 27. As a result, the insulating resin of NCP 79 is smoothly removed from the bonding surface and remains in this space, and the bonding portion 75 and the wiring 71 are stably fixed. In this way, it is possible to provide a mounting structure for the flexible circuit board 27 that can prevent the occurrence of defective electrical bonding and stably obtain a highly reliable bonding structure. In addition, this configuration can be easily realized only by changing the pattern design from the lead electrode 47 to the terminal 74 on the flow path forming substrate 22.

  According to this embodiment, since the flexible circuit board 27 is mounted on the flow path forming substrate 22 using the mounting structure described above, the electrical connection reliability is high, and the high-quality liquid droplet ejection head 1 is provided. Can be realized.

[Second Embodiment]
Hereinafter, the mounting structure of the flexible circuit board of 2nd Embodiment of this invention is demonstrated using FIGS. 8-9.
FIG. 8 is a plan view of the terminal portion of the flow path forming substrate. FIG. 9 is a plan view showing a state in which the flexible circuit board is overlaid on the terminal portion.

  In the first embodiment, as illustrated in FIG. 6, the configuration example in which the terminal 74 extends from one side (the right side in FIG. 6) of the opening 60 of the flow path forming substrate 22 has been described. On the other hand, in this embodiment, as shown in FIG. 8, the terminals 74A and 74B extend from the two opposite sides (the right side and the left side in FIG. 8) of the opening 60 of the flow path forming substrate 22. . Then, as shown in FIG. 9, the wiring 71 of one flexible circuit board 27 is superimposed on the plurality of terminals 74A extending from the right side of FIG. 8 and the plurality of terminals 74B extending from the left side of FIG. And electrical connection is made.

  Also in the present embodiment, as in the first embodiment, the terminals 74A and 74B are composed of a wiring bent portion 76 and a joint portion 75, and the joint portion 75 is separated from the extension line D of the lead electrode 47 (wiring). It is arranged at a position (below the extension line D in FIG. 8).

  Also in the mounting structure of the present embodiment, since the bonding area between the terminals 74A and 74B and the wiring 71 is reduced, the press bonding property between the bonding portion 75 and the wiring 71 and the discharge property of NCP are increased. The same effects as those of the first embodiment can be obtained such that generation can be prevented and a highly reliable joint structure can be stably realized.

[Third Embodiment]
Hereinafter, the mounting structure of the flexible circuit board of 3rd Embodiment of this invention is demonstrated using FIGS. 10-12.
FIG. 10 is a cross-sectional view showing the flexible circuit board mounting structure of the present embodiment. FIG. 11 is a plan view of the terminal portion of the flow path forming substrate. FIG. 12 is a plan view showing a state in which the flexible circuit board is overlaid on the terminal portion.

  In the first and second embodiments, the lead electrode 47 and the joint 75 on the flow path forming substrate 22 are located on the same plane. On the other hand, in the mounting structure of the present embodiment, as shown in FIG. 10, the bonding portion 85 is formed on the insulating film (not shown) on the upper surface (first surface) of the flow path forming substrate 22, An extension 47b (conductive portion) of the lead electrode 47 is formed on a surface (second surface) different from the upper surface of the insulating film (not shown). In addition, a through hole 81 penetrating an arbitrary layer 83 between the first surface and the second surface is formed, and a conductive material is embedded in the through hole 81 to form the relay conduction portion 82. The relay conduction part 82 may be formed integrally with the extension part 47b of the lead electrode 47 or may be formed integrally with the joint part 85 according to the manufacturing process.

  In the case of the present embodiment, since the extended portion 47b of the lead electrode 47 is formed on a surface different from the upper surface of the insulating film, each bonding portion 85 has an isolated form on the upper surface of the insulating film as shown in FIG. Become. With this configuration, the dimension of the bonding portion 85 in the wiring extending direction is smaller than the dimension of the wiring 71 in the extending direction of the wiring 71 in the board bending portion 27 </ b> A of the flexible circuit board 27. Further, the joint portion 85 and the extension portion 47 b of the lead electrode 47 are electrically connected via the relay conduction portion 82.

  There are various possible forms (layers) for forming the extended portion 47b (conductive portion) of the lead electrode 47. For example, in FIG. 4, a through-hole penetrating the insulating film (not shown), the lower electrode film 42, and the elastic film 41 may be formed and disposed on the lower layer side of the elastic film 41. Furthermore, in addition to the above layers, a through-hole penetrating the flow path forming substrate 22 may be formed and disposed on the lower surface side of the flow path forming substrate 22.

  Also in the mounting structure of the present embodiment, since the bonding area between the bonding portion 85 and the wiring 71 is reduced, the bonding property between the bonding portion 85 and the wiring 71 and the NCP discharge performance are increased. The same effects as those of the first and second embodiments can be obtained, such that a highly reliable joint structure can be stably realized. In the case of this embodiment, since the wiring bent portion as in the first and second embodiments is not necessary, the wiring and the joint can be formed on the same straight line when viewed from the normal direction of the substrate. Wiring routing design becomes easy.

[Fourth Embodiment]
Hereinafter, the mounting structure of the flexible circuit board of 4th Embodiment of this invention is demonstrated using FIGS.
FIG. 13 is a cross-sectional view showing the flexible circuit board mounting structure of the present embodiment. FIG. 14 is a plan view of the terminal portion of the flow path forming substrate. FIG. 15 is a plan view showing a state in which the flexible circuit board is overlaid on the terminal portion.

  Also in the mounting structure of the present embodiment, as in the third embodiment, as shown in FIG. 13, the extended portion 47c (conductive portion) of the lead electrode 47 is a surface (second surface) different from the upper surface of the insulating film (not shown). ) Is formed on. In addition, a through hole 91 that penetrates the layer 83 between the first surface and the second surface is formed, and a conductive material is embedded in the through hole 91 to form the relay conduction portion 92. With this configuration, the dimension of the bonding portion 95 in the wiring extending direction is smaller than the dimension of the wiring 71 in the extending direction of the wiring 71 in the board bending portion 27A of the flexible circuit board 27, and the bonding portion 95 and the lead electrode 47 are extended. The part 47 c is electrically connected via the relay conduction part 92.

  In the case of this embodiment, the formation position of the relay conduction | electrical_connection part 92 differs from 3rd Embodiment. That is, in the third embodiment, the relay conducting portion 82 is formed in the joining region of the joining portion 85 to which the wiring 71 of the flexible circuit board 27 is joined. On the other hand, in the mounting structure of the present embodiment, as shown in FIG. 13, the relay conducting portion 92 is outside the joining region of the joining portion 95 to which the wiring 71 of the flexible circuit board 27 is joined, It arrange | positions on the outer side of the bending part 27A.

  Also in the mounting structure of the present embodiment, since the bonding area between the bonding portion 95 and the wiring 71 is reduced, the press bonding property between the bonding portion 95 and the wiring 71 and the NCP discharge property are increased. The same effects as those of the first to third embodiments can be obtained, which can be prevented and a highly reliable joint structure can be realized stably. In addition, since the wiring 71 and the joint portion 95 can be formed on the same straight line, the same effect as that of the third embodiment can be obtained in that the wiring design is facilitated.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. The mounting structure of the flexible circuit board in the above embodiment and the specific configuration of each part of the droplet discharge head using this mounting structure are not limited to the above embodiment, and can be changed as appropriate.

  DESCRIPTION OF SYMBOLS 1 ... Droplet discharge head, 22 ... Channel formation board | substrate (1st board | substrate), 23 ... Piezoelectric element (drive element), 26, 26A, 26B ... Driver IC (drive circuit part), 27 ... Flexible circuit board (2nd) Substrate), 71 ... wiring, 74, 74A, 74B ... terminal, 75, 85, 95 ... junction, 76 ... wiring bent part, 79 ... non-conductive adhesive, 81, 91 ... through hole, 82, 92 ... Relay conduction part.

Claims (7)

A first substrate having a first surface and a terminal extending in the first direction provided on the first surface;
A second substrate having a facing surface facing the first surface and having a wiring extending in the first direction provided on the facing surface;
A non-conductive adhesive that is provided between the first surface and the facing surface, and that bonds the first substrate and the second substrate in a state where the terminal and the wiring face each other in direct contact with each other; With
The board mounting structure according to claim 1, wherein a length in the first direction of the joint portion in direct contact with the wiring in the terminal is shorter than a length in the first direction of the wiring on the facing surface.   The said terminal is provided with the said junction part, and the wiring bending part extended in the 2nd direction electrically connected with the said junction part and crossing the said 1st direction. PCB mounting structure.   The board mounting structure according to claim 2, wherein the wiring bent portion extends in a direction obliquely intersecting the first direction. The terminal includes the joint provided on the first surface of the first substrate, the conductive portion provided on a second surface different from the first surface of the first substrate, the first surface, and the A relay conduction part formed in a through hole penetrating the layer between the second surface,
The board mounting structure according to claim 1, wherein the joint portion and the conductive portion are electrically connected via the relay conducting portion.   5. The substrate mounting structure according to claim 1, wherein a bonding surface of the bonding portion and a bonding surface of the wiring are flat surfaces. 6. A first substrate provided with a terminal provided on the first surface and extending in a first direction; and a driving element that is electrically connected to the terminal and generates a pressure for discharging a droplet;
A second substrate provided with a wiring provided on a facing surface facing the first surface and extending in the first direction; and a drive circuit unit electrically connected to the wiring and driving the drive element; ,
A non-conductive adhesive that is provided between the first surface and the facing surface, and that bonds the first substrate and the second substrate in a state where the terminal and the wiring face each other in direct contact with each other; With
The droplet discharge head according to claim 1, wherein a length in the first direction of the joint portion in direct contact with the wiring in the terminal is shorter than a length in the first direction of the wiring in the facing surface. A drive circuit section for driving the drive element on a first substrate having a drive element for generating a pressure for discharging droplets and a plurality of terminals extending in a predetermined extending direction; A second substrate made of a flexible circuit board provided with a plurality of wirings extending in the same direction as the current direction, and each of the terminals and each of the wirings are electrically connected to each other so that the driving element and the wiring A droplet discharge head electrically connected to the drive circuit unit,
The second substrate is bent in a direction intersecting with the extending direction, and the wirings of the substrate bent portion and the terminals of the first substrate, which are closer to the front end side of the substrate than the bent portion of the second substrate, In a state of being opposed to each other, the first substrate and the second substrate are bonded by a non-conductive adhesive,
Among the terminals of the first substrate, the dimension in the extending direction of the joint portion that is in direct contact with the wiring is larger than the dimension in the extending direction of the wiring in the substrate bent portion of the second substrate. A droplet discharge head characterized by being small.

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