JP2007276157A - Liquid droplet delivering head and liquid droplet delivering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet delivering head capable of ensuring a high density wiring region for a wiring pattern on an existing wiring substrate and capable of implementing the wiring pattern at high density, and to provide a liquid droplet delivering apparatus. <P>SOLUTION: The liquid droplet delivering head 1 for delivering a liquid stored as liquid droplets toward a face to be delivered from a plurality of nozzles 12a has a plurality of opening parts 25 for electric joining which connects electrically a bump land part 23b of the wiring pattern 23 with a pressure generating element 13 through a solder bump 21 on a cover layer 24 of the wiring substrate 20. The opening part 25 for electric joining is formed smaller than the bump land part 23b of the wiring pattern 23. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet discharge head and a droplet discharge device, and more particularly, to a droplet discharge head and a droplet discharge device including a droplet discharge head that achieve high density component mounting.

  Conventionally, for example, by driving a plurality of piezoelectric / electrostrictive actuator elements, pressure is applied to the ink stored in the pressure generating chamber, and the liquid is made into fine droplets from the plurality of nozzles toward the ejection surface. 2. Related Art Inkjet recording heads that record information by discharging are known. As this type of recording head, for example, a structure in which a plurality of piezoelectric / electrostrictive actuator elements are arranged in a matrix in order to increase the density of a plurality of nozzles has been proposed (for example, see Patent Document 1).

  The ink jet recording head described in Patent Document 1 is a piezoelectric / electrostrictive actuator element (hereinafter referred to as “piezoelectric element”) having a lattice arrangement structure disposed on a substrate at a pitch corresponding to a pressure generation chamber communicating with a nozzle. And a flexible printed wiring board (hereinafter referred to as “FPC”) having a plurality of wiring patterns joined to individual piezoelectric elements. This piezoelectric element has an actuator area (electrode driving part) for applying pressure to ink stored in the pressure generating chamber and an electric bonding area (electrode pad part) on the same surface. The area for electric bonding of the piezoelectric element is electrically connected to the electric bonding pad (bump land portion) of the FPC wiring pattern via a solder bump. A plurality of wirings routed from the electrical bonding pads of the individual FPCs are arranged adjacent to each other through gaps between desired pads of the individual electrical bonding pads. A coverlay is covered on the wiring pattern of the FPC, and the coverlay has openings that expose the solder bumps formed on the plurality of electrical bonding pads.

In joining the electrical bonding area of the piezoelectric element and the solder bump of the FPC, first, the piezoelectric element and the FPC are opposed to each other. Next, the electric bonding areas of the plurality of piezoelectric elements and the plurality of solder bumps of the FPC are positioned so as to match each other. Next, the plurality of piezoelectric elements and the plurality of solder bumps of the FPC are electrically connected to each other by performing heating, pressurization, or vibration.
Japanese Patent Laid-Open No. 2003-69103 (FIGS. 1 to 5 and the description thereof)

  By the way, in the ink jet recording head described in Patent Document 1, as described above, a cover lay made of an insulating material is coated on the wiring pattern excluding the plurality of FPC pads for electrical bonding. . This cover lay is due to changes over time such as thermal expansion and contraction due to heat release of solder bumps generated when solder bumps are formed on a plurality of electrical bonding pads of FPC, or thermal history of FPC generated after solder bump formation, for example. It serves to prevent short-circuits between a plurality of adjacent solder bumps of the FPC, between the solder bumps of the FPC and the wiring pattern adjacent thereto, and between adjacent wiring patterns.

  On the other hand, in the conventional ink jet recording head having such a configuration, the FPC coverlay fluctuates from the normal position (dimension fluctuation) when the electric bonding area of the piezoelectric element and the solder bump of the FPC are bonded. There is. Even in such a case, it is important to be able to absorb misalignment of the FPC coverlay with respect to the FPC electrical bonding pad. Therefore, in the conventional ink jet recording head, in consideration of the positional deviation amount with respect to the wiring pattern of the coverlay, in addition to the minimum wiring pitch of the FPC wiring pattern, the FPC electrical bonding pad and its pad It is necessary to determine an interval between adjacent wirings.

  In general, in a conventional ink jet recording head, the amount of displacement with respect to the wiring pattern of the FPC coverlay is larger than the minimum wiring pitch of the wiring pattern of the FPC. For this reason, the distance between the FPC electrical bonding pads and the wiring adjacent to the pads greatly depends on the positional deviation amount of the FPC coverlay with respect to the wiring pattern. As a result, the conventional ink jet recording head has an FPC coverlay that exposes the solder bumps rather than the FPC electrical bonding pads (solder bumps) in order to absorb misalignment of the FPC coverlay with respect to the wiring pattern. The size of the opening is set to a larger size, and solder bumps are formed on the entire surface of the electrical bonding pad exposed in the opening (see FIG. 7B).

  However, the permissible area (positional deviation amount) for absorbing the positional deviation of the FPC coverlay with respect to the wiring pattern is a waste space (dead space) on the wiring in which the FPC wiring pattern cannot be formed. It was. As a result, there is a problem that the wiring density is lowered due to the line width and width pitch of the FPC wiring pattern, and it is difficult to achieve high-density mounting of the FPC wiring pattern. In addition, there is a problem that a large recording head having a large number of nozzles or a high-density recording head is a major obstacle to miniaturization and high density.

  In the ink jet recording head described in Patent Document 1, solder bumps are formed on the entire surface of the electrical bonding pads exposed in the openings of the FPC coverlay. No mention is made of absorbing the misalignment.

  The present invention has been made to solve the above-described conventional problems, and it is possible to secure a high-density wiring area of a wiring pattern on an existing wiring board and to realize high-density mounting of the wiring pattern. It is an object of the present invention to provide a liquid droplet discharge head and a liquid droplet discharge apparatus including the liquid droplet discharge head.

[1] The present invention is a droplet discharge head that discharges a stored liquid as droplets from a plurality of nozzles toward a discharge target surface, the plurality of nozzles, and a plurality of nozzles communicating with the plurality of nozzles A head body having a pressure generating chamber and a plurality of pressure generating elements provided corresponding to the plurality of pressure generating chambers, a base layer, and a bump land electrically connected to a wiring formed on the base layer A plurality of wiring patterns having a portion and a wiring substrate having a cover layer covering the plurality of wiring patterns, wherein the cover layer bumps the bump land portion of the wiring pattern and the pressure generating element. A plurality of openings for electrical connection for electrical connection via the wiring pattern, wherein the openings for electrical connection are formed smaller than the bump land portions of the wiring pattern. In the liquid droplet ejection head according to symptoms.

  According to the above configuration, the bump is provided in the opening for electrical bonding of the cover layer formed smaller than the bump land portion of the wiring pattern of the wiring board. As a result, the interval between the bump land portion of the wiring pattern and the wiring can be shortened, and the wiring area can be formed between the adjacent bump land portions while ensuring the wiring area. A high-density mounting of the wiring pattern of the substrate can be achieved.

[2] In the invention described in [1] above, the bump land portion of the wiring pattern has a bump forming surface having the same size as the opening for electrical connection. Bumps can be formed protrudingly in the electrical bonding opening, and the amount of bump displacement relative to the bump land can be reduced.

[3] In the invention described in [1] above, the bumps are formed by metal plating or solder balls. As bumps for electrically connecting the pressure generating element and the wiring board, various bumps such as metal plating, solder balls, anisotropic conductive films and solder bumps can be used.

[4] In the invention described in [1] above, the pressure generating elements are arranged in a matrix. Coupled with the high density of the plurality of nozzles, the pitch between the plurality of pressure generating elements can be narrowed, and a high-density wiring region can be obtained.

[5] In the invention described in [1] or [4] above, the pressure generating element has a first alignment mark for positioning and corresponds to the first alignment mark on the wiring board. And a second alignment mark. The head body and the wiring board can be bonded together with high accuracy. There is no need to provide a special alignment mark, and the entire droplet discharge head can be reduced in size and size.

[6] In the invention described in [5], the pressure generating element includes a plate-like piezoelectric element and a plate-like extending end portion formed on the piezoelectric element, and the first An alignment mark is formed by the extended end portion. Simultaneously with the formation of the piezoelectric element, the first alignment mark can be integrally formed. As the pressure generating element, for example, a piezoelectric element (lead zirconate titanate) can be used. For example, various pressure generating elements utilizing deformation such as an electrothermal conversion element or a magnetostrictive element can be used. The first alignment mark can be formed in any form such as a cross-shaped notch, slit, or through hole formed at the extended end of the piezoelectric element, for example.

[7] In the invention described in [5] above, the cover layer of the wiring board has an opening window for positioning recognition at a portion corresponding to the pressure generating element, and the second alignment mark is The opening window is formed by the opening window. Simultaneously with the formation of the opening for electrical connection of the cover layer, the second alignment mark can be formed integrally. Inspecting the bonding state between the pressure generating element and the bump of the wiring board while visually confirming the first alignment mark of the pressure generating element or by optical detection through the opening window of the wiring board. Can do.

[8] In the invention described in [7] above, the second alignment mark is formed by an uncut portion of the cover layer remaining in the opening window. Various alignment marks can be easily and accurately formed simultaneously with the formation of the opening for electrical connection of the cover layer.

[9] Further, the present invention is a liquid droplet ejection apparatus including a plurality of liquid droplet ejection heads that eject liquid as liquid droplets from a plurality of nozzles toward an ejection surface by driving a plurality of piezoelectric elements. The droplet discharge head includes a plurality of nozzles, a plurality of pressure generating chambers communicating with the plurality of nozzles, and a plurality of pressure generating elements provided corresponding to the plurality of pressure generating chambers. And a base layer, a plurality of wiring patterns having bump land portions electrically connected to the wiring formed on the base layer, and a wiring substrate having a cover layer covering the plurality of wiring patterns. The cover layer has a plurality of openings for electrical connection for electrically connecting the bump land portion of the wiring pattern and the pressure generating element via bumps, and the electrical connection opening. Parts is in droplet ejection apparatus characterized by comprising is formed smaller than the bump land portion of the wiring pattern.

  The droplet discharge head of the present invention can be suitably used for a droplet discharge device such as a color printer. The droplet discharge device can be easily reduced in size, size, and cost. A droplet discharge device in which a plurality of droplet discharge heads are unitized by a head body having a high-density wiring area is obtained.

  The present invention can obtain a wiring board having a high-density wiring region of a wiring pattern, and can achieve high-density mounting of the wiring pattern of the wiring board, and the liquid droplet discharging head. It is possible to obtain a droplet discharge device including

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

[First Embodiment]
(Configuration of droplet discharge head)
FIG. 1 is a cross-sectional view schematically showing a main part of a droplet discharge head according to a first embodiment of the present invention, and FIG. 2 shows a pressure generating element that is a component of the droplet discharge head. FIG. 3A is a partial plan view schematically showing an example, FIG. 3A is a partial plan view schematically showing an example of the structure of a flexible wiring board that is one component of a droplet discharge head, and FIG. FIG. 4 is a cross-sectional view taken along line III-III in FIG.

  In FIG. 1, reference numeral 1 denotes a droplet discharge head according to the first embodiment. As shown in FIG. 1, the droplet discharge head 1 is configured so that liquids stored in a plurality of pressure generating chambers 11,..., 11 are formed as droplets from a plurality of nozzles 12a,. A head main body 10 for discharging is provided. The head body 10 is provided with a plurality of pressure generating elements 13,..., 13 provided corresponding to the plurality of pressure generating chambers 11. A flexible printed wiring board 20 (hereinafter referred to as “FPC 20”) for applying a voltage is electrically connected to the plurality of pressure generating elements 13 via bumps 21. The head body 10 drives the plurality of pressure generating elements 13 via the FPC 20 to discharge the liquid stored in the plurality of pressure generating chambers 11 as droplets from the plurality of nozzles 12a toward the discharge target surface. It is supposed to be.

  Next, the head body 10 and the FPC 20 will be specifically described.

(Head body)
As shown in FIG. 2, the head body 10 according to the first embodiment includes a droplet discharge region 16 that contributes to discharging droplets and a dummy region 18 that is not used to discharge droplets. It is divided. The dummy region 18 is formed so as to surround the outermost periphery of the droplet discharge region 16. As shown in FIG. 1, the plurality of nozzles 12 a that eject ink are formed on the nozzle plate 12 corresponding to the pressure generating elements 13. On the nozzle plate 12, a diaphragm 15 provided via a plurality of partition walls 14,..., A plurality of pressure generating chambers 11 partitioned between the nozzle plate 12 and the diaphragm 15, and respective pressures And a plurality of pressure generating elements 13 provided corresponding to the generating chamber 11.

  As shown in FIG. 2, the plurality of pressure generating elements 13 provided corresponding to the pressure generating chambers 11 are arranged in an obliquely inclined matrix form on the diaphragm 15. As shown in FIG. 1, the plurality of nozzles 12 a of the nozzle plate 12 are provided corresponding to the respective pressure generation chambers 11. The pressure generating chamber 11 is provided in communication with the nozzle 12a and an ink tank (not shown).

(Pressure generating element)
As shown in FIG. 1, a plurality of pressure generating elements 13 in the form of an oblique matrix arranged at a predetermined interval on a vibration plate 15 arranged in the droplet discharge region 16 are pressure generation chambers for discharging ink. 11 functions as a pressure generating element that contributes to the application of pressure. As the pressure generating element 13, for example, a pressure generating element using deformation such as a piezoelectric element (lead zirconate titanate), an electrothermal conversion element, or a magnetostrictive element can be used. As shown in FIG. 2, the pressure generating element 13 in the first embodiment is composed of a rectangular flat plate-shaped piezoelectric element 13 having a high density matrix arrangement structure.

  First and second electrode layers (not shown) are formed on the upper and lower surfaces of the piezoelectric element 13, respectively. As shown in FIGS. 1 and 2, the piezoelectric element 13 is functionally divided into an electrode driving unit 13a and an electrode pad unit 13b. As shown in FIG. 1, the electrode driving portion 13a of the piezoelectric element 13 is joined to the position of the vibration plate 15 corresponding to the pressure generating chamber 11, and the lower surface (not shown) of the lower surface is also shown by a conductive adhesive not shown. The diaphragm 15 is electrically connected through two electrode layers. As shown in FIG. 1, the electrode pad portion 13 b of the piezoelectric element 13 is bonded onto the vibration plate 15 corresponding to the partition wall 14 and is electrically connected to the bump 21 of the FPC 20.

  In the droplet discharge head 1 configured as described above, when an electrical signal from a control circuit (not shown) is applied to the electrode pad portion 13b of the piezoelectric element 13 via the FPC 20, the electrode driving portion 13a of the piezoelectric element 13 is The electrode pad portion 13b is deformed in the vertical direction with the fulcrum serving as a fulcrum, and the diaphragm 15 is bent and deformed along with the deformation. Ink from an ink tank (not shown) is supplied to the pressure generation chamber 11. Pressure is generated by changing the volume in the pressure generating chamber 11 and applying pressure to the ink stored in the pressure generating chamber 11 via the diaphragm 15 that is bent and deformed in the vertical direction by the piezoelectric element 13. The ink in the chamber 11 is ejected as droplets from the nozzle 12a toward the ejection surface.

(Dummy pressure generating element)
As shown in FIG. 2, the plurality of dummy pressure generating elements 17,..., 17 are arranged on the diaphragm 15 disposed in the dummy region 18 and are arranged in one row along the outermost periphery of the piezoelectric element 13 having an oblique matrix shape. Are arranged in a rectangular frame. As shown in FIG. 1, the plurality of dummy pressure generating elements 17 function as dummy pressure generating elements that do not contribute to the application of pressure in the pressure generating chamber 11 when ink is ejected without applying a voltage. In the dummy area 18, a dummy nozzle that is not used for discharging droplets and a dummy pressure generating chamber corresponding to the dummy nozzle are arranged. In the illustrated example, the nozzle 15a and the pressure generating chamber 11 are provided on the diaphragm 15, but the present invention is not limited to this. In the present invention, for example, the diaphragm 15 is provided between the nozzle plate 12 and the diaphragm 15 corresponding to the dummy pressure generating element 17 without providing the wiring pattern 23, the nozzle 12 a and the pressure generating chamber 11 in the diaphragm 15. Of course, it is good also as a structure.

  As shown in FIG. 2, the piezoelectric element 13 and the dummy piezoelectric element 17 are arranged on the same plane with the same size, the same shape, and the same pitch. The boundary between the piezoelectric element 13 and the dummy piezoelectric element 17 is set to have the same dimensional spacing as the separation groove between the piezoelectric elements 13. The dummy piezoelectric element 17 has a function of increasing the bonding reliability and mechanical strength when the nozzle plate 12 is bonded to the vibration plate 15, and can reduce the variation in rigidity of the piezoelectric element 13. It is possible to prevent the discharge characteristics from being varied for each nozzle 12a. In addition, it is possible to prevent the influence of side etching that occurs during sandblasting, and it is possible to ensure high dimensional stability in the piezoelectric element 13. In the first embodiment, the dummy piezoelectric element 17 is disposed so as to surround the piezoelectric element 13 that contributes to the pressure application of the pressure generating chamber 11 when ink is ejected. However, the present invention is not limited to this. For example, the piezoelectric elements 13 and the dummy piezoelectric elements 17 may be alternately arranged on the outermost periphery of the droplet discharge region 16.

(Dummy piezoelectric element alignment mark)
In the first embodiment, the dummy electrode pad portion 17b of the dummy piezoelectric element 17 serves as a mark for positioning and bonding the FPC 20 at a regular position as shown in FIG. It is configured as an alignment mark. It is preferable that at least two first alignment marks are formed in the dummy region 18.

(FPC)
As shown in FIGS. 3A and 3B, the FPC 20 that applies a voltage to the piezoelectric element 13 through the bumps 21 includes a base layer 22 made of a flexible insulating material, and a base layer 22 on the base layer 22. It has a three-layer structure including a wiring pattern 23 having a circular bump land portion 23b electrically connected to the formed wiring 23a, and a cover layer 24 made of an insulating material covering the wiring pattern 23. As shown in FIGS. 1 and 2, the bump land portion 23b of the wiring pattern 23 is formed corresponding to the electrode pad portion 13b of the piezoelectric element 13 arranged in an oblique matrix. A plurality of wirings 23a routed from the bump land portion 23b of the FPC 20 are arranged adjacent to each other through gaps between desired land portions of the bump land portion 23b, as shown in FIGS. 3 (a) and 3 (b). Has been. On the bump land portion 23b of the wiring pattern 23, as shown in FIG. As the bump 21 for electrically connecting the piezoelectric element 13 and the FPC 20, a hemispherical solder bump 21 having a conductive plating layer on the surface of a conductive core material is used as shown in FIG. 4 (d). can do. As other bumps, for example, various bumps such as a spherical solder ball having a conductive plating layer on the surface of a conductive core material or an anisotropic conductive film can be used.

  As shown in FIGS. 3A and 3B, the cover layer 24 of the FPC 20 formed to protect the wiring 23a has bump land portions 23b of the wiring pattern 23 and electrode pad portions of the piezoelectric element 13. A circular electrical joint opening 25 is formed for electrical connection to 13b via the solder bump 21. The electrical bonding opening 25 has the main features in the first embodiment. In the first embodiment, the electrical bonding opening 25 is an opening for forming a soldering land. A part of the lower bottom portion of the opening has a stepped shape having a circular bump land portion opening outward from the inner peripheral surface. The electrical bonding opening 25 has a circular opening with a smaller diameter than the circular opening of the bump land opening, and is formed with a diameter smaller than the diameter of the bump land 23 b of the wiring pattern 23. The bump land portion 23b has a bump forming surface having the same size as the electrical bonding opening 25.

(FPC alignment mark)
As shown in FIGS. 1 to 3B, the cover layer 24 of the FPC 20 is used for positioning recognition for aligning the dummy piezoelectric element 17 at a position corresponding to the dummy electrode pad portion 17 b of the dummy piezoelectric element 17. The opening window 26 is integrally formed simultaneously with the formation of the opening 25 for electrical connection. The opening window 26 is configured as a second alignment mark (positioning mark). The second alignment mark and the first alignment mark of the dummy piezoelectric element 17 have other main features in the first embodiment. As shown in FIGS. 1 and 2, the positioning recognition opening windows 26 are arranged in the same shape and pitch as the electrical bonding openings 25, and are different in shape and pitch from the dummy electrode pad portions 17. It is arranged with. When the piezoelectric elements 13 having the matrix arrangement structure and the FPC 20 are joined, the first alignment marks of the dummy piezoelectric elements 17 are visually detected or optically detected through the opening window 26 for positioning recognition. On the other hand, the piezoelectric elements 13 and the FPCs 20 having the matrix arrangement structure can be bonded together with high accuracy without accumulating variations in alignment accuracy.

  In the first embodiment, the positioning recognition opening windows 26 are arranged with different shapes and the same pitch as the electrical bonding openings 25 and the dummy electrode pad portions 17b. However, the present invention is not limited to this. Is not to be done. As the positioning recognition opening window portion 26, for example, the positioning recognition opening window portion 26 is arranged with the same shape and the same pitch as the dummy electrode pad portion 17b, or with a different shape and the same pitch as the solder bump 21. can do. Further, the second alignment mark of the FPC 20 can be formed by the uncut portion of the cover layer remaining in the portion corresponding to the dummy electrode pad portion 17b of the cover layer 24.

(FPC manufacturing method)
Below, the manufacturing method of FPC20 is demonstrated, referring FIG. FIG. 4A to FIG. 4E are schematic explanatory views for explaining a manufacturing process of the FPC 20.

  The FPC 20 configured as described above can be manufactured according to a conventional method. In manufacturing the FPC 20, first, the copper-clad base film 22 masked with a circuit pattern forming resist is etched. Next, a desired wiring pattern 23 is formed on the base film 22 by dissolving the copper foil layer of the non-masking portion and removing the copper foil except for the wiring pattern 23 (see FIG. 4A). Next, the surface of the wiring pattern 23 on the base film 22 is covered with a polyimide film and bonded. Thereafter, a predetermined portion of the polyimide film is etched to expose a part of the copper foil corresponding to the bump land portion 23b of the wiring pattern 23 to form a bump forming surface, and for positioning with respect to the piezoelectric element 13 An opening window 26 for positioning recognition, which is a hole as a first alignment mark, is formed (see FIG. 4B). Next, a hemispherical solder bump 21 is formed on the bump formation surface by plating (see FIG. 4C). Thereafter, external processing and inspection of the FPC 20 are performed to obtain the FPC 20 shown in FIG. Although an example is shown in which bumps are formed by plating, bumps are formed by spherical solder balls 21a having a conductive plating layer on the surface of a conductive core material as shown in FIG. 4 (e). Of course, may be formed. The FPC 20 manufactured as described above is connected to the piezoelectric element 13 according to a conventional method.

(Method for manufacturing droplet discharge head)
Hereinafter, a method of manufacturing the droplet discharge head according to the first embodiment configured as described above will be described with reference to FIG. FIG. 5A to FIG. 5C are schematic explanatory diagrams for explaining a method of joining the FPC 20 and the piezoelectric element 13.

  In joining the electrode pad portion 13b of the piezoelectric element 13 and the solder bump 21 of the FPC 20, first, the piezoelectric element 13 and the FPC 20 are opposed to each other. Next, both the dummy electrode pad portion 17b (first alignment mark) of the dummy piezoelectric element 17 and the opening window portion 26 (second alignment mark) for positioning recognition of the cover layer 24 of the FPC 20 are visually aligned. Automatic alignment is performed using a camera and an image processing apparatus (see FIG. 5A). Next, the plurality of electrode pad portions 13b and the plurality of solder bumps 21 are bonded to each other (see FIG. 5B). Next, by heating, pressurizing, or vibrating, the plurality of solder bumps 21 are melted, and the plurality of electrode pad portions 13b and the plurality of solder bumps 21 are electrically connected to each other (FIG. 5C). reference). Thereafter, the bonding state of the plurality of piezoelectric elements 13 and the plurality of solder bumps 21 of the FPC 20 is visually confirmed through the opening window 26 for positioning recognition of the cover layer 24 of the FPC 20, so that the solder bump 21 of the FPC 20 is surely soldered. Check if it is attached.

  Hereinafter, more specific examples of the present invention will be described together with comparative examples with reference to FIGS. 3B and 6 to 7B. First, the design items described in the examples and comparative examples will be described.

(FPC)
Solder bump diameter ΦB (0.2mm)
Bump land diameter ΦD
Cover joint opening diameter ΦC
Maximum deviation of cover electrical joint opening diameter ΦC '(= ΦC + 0.2mm)
Wiring pattern minimum wiring pitch L (0.028mm)
Wiring pattern installation space S (0.028mm)
Spacing between bump land and wiring pattern Q (minimum 0.028mm)
Spacing dimension between bump lands P (1.530mm)
Number of wiring patterns between bump lands n

[Example]
FIG. 6 is a partial plan view schematically showing an example of the wiring pattern 23 of the FPC 20 according to the first embodiment. In the figure, reference numeral 20 denotes an FPC formed in the opening portion 25 for electrical bonding in which the solder bump 21 has a diameter smaller than the diameter of the bump land portion 23 b of the wiring pattern 23. When the droplet discharge head 1 is obtained by bonding the FPC 20 and the piezoelectric element 13 based on the manufacturing method shown in FIGS. 5A to 5C, the wiring pattern 23 and the solder bump 21 in FIG. The deviation ΔB from the center of the FPC 20 is ± 20 μm, the alignment recognition deviation ΔC of the second alignment mark of the FPC 20 is ± 10 μm, and the deviation of the electrode pad portion 13b of the piezoelectric element 13 from the first alignment mark of the piezoelectric element 13 ΔD was ± 3 μm, the positional recognition deviation ΔE of the first alignment mark of the piezoelectric element 13 was ± 10 μm, and the positional deviation amount ΔF due to bonding / soldering between the piezoelectric element 13 and the FPC 20 was ± 20 μm. As a result, the positional deviation amount ΔA (FIG. 3B) between the wiring pattern 23 and the cover layer 24 can be reduced, and the position of the electrode pad portion 13b of the piezoelectric element 13 and the solder bump 21 of the FPC 20 is reduced. The deviation amount ΔT was ± 63 μm (ΔT = ΔB + ΔC + ΔD + ΔE + ΔF). The number n of the wiring patterns 23 that can be wired between the bump land portions 23b was 16.

[Comparative example]
FIG. 7A is a partial plan view schematically showing the wiring pattern 23 of the FPC 20 of the comparative example, and FIG. 7B is a cross-sectional view taken along the line VII-VII in FIG. . In these drawings, reference numeral 20 indicates an FPC formed in the opening portion 25 for electrical bonding in which the solder bump 21 has a diameter larger than the diameter of the bump land portion 23 b of the wiring pattern 23. In FIGS. 7A and 7B, substantially the same members as those in the above embodiment are given the same member names and symbols.

  When the droplet discharge head 1 was obtained by the manufacturing method shown in FIGS. 5A to 5C similar to that in the above embodiment, the wiring pattern 23 and the cover layer 24 in FIGS. 7A and 7B were obtained. The displacement ΔA is ± 100 μm, the displacement ΔB between the wiring pattern 23 and the center of the solder bump 21 is ± 20 μm, the alignment recognition displacement ΔC of the second alignment mark of the FPC 20 is ± 10 μm, and the electrode pad of the piezoelectric element 13 The deviation ΔD between the first alignment mark of the portion 13b and the piezoelectric element 13 is ± 3 μm, the alignment recognition deviation ΔE of the first alignment mark of the piezoelectric element 13 is ± 10 μm, and the bonding / soldering between the piezoelectric element 13 and the FPC 20 The misregistration amount ΔF due to attachment was ± 20 μm. As a result, the displacement ΔS between the electrode pad portion 13b of the piezoelectric element 13 and the solder bump 21 of the FPC 20 was ± 163 μm (ΔS = ΔA + ΔB + ΔC + ΔD + ΔE + ΔF). The number n of wiring patterns 23 that can be wired between the bump land portions 23b was thirteen.

  As described above, the first embodiment in which the solder bumps 21 are provided in the opening portions 25 for the electrical connection of the cover layer 24, compared with the conventional droplet discharge head structure in which the solder bumps 21 are provided on the entire surface of the bump land portion 23b of the wiring pattern 23. In the droplet discharge head structure according to the embodiment, a sufficient installation area for forming the wiring pattern 23 can be secured between the adjacent bump land portions 23b. For this reason, it becomes possible to increase the number of the wiring patterns 23 of the FPC 20, and it can be understood that the pitch of the piezoelectric elements 13 can be reduced by about 100 μm.

  The above configuration is a configuration showing an example of the liquid droplet ejection head of the first embodiment, and the structure, shape, and constituent members thereof are not limited to the illustrated examples.

(Modification of FPC)
FIG. 8A and FIG. 8B show Modification 1 of the FPC 20 according to the first embodiment. FIG. 8A is a partial cross-sectional view of the FPC 20, and FIG. 8B is a partial plan view of the FPC 20.

  In these figures, the point of great difference from the first embodiment is that a positioning recognition opening window 26 is formed as a cross-shaped second alignment mark in a part of the cover layer 24 of the FPC 20. is there. Accordingly, in these drawings, substantially the same members as those in the first embodiment are given the same member names and reference numerals.

  As shown in FIGS. 8 (a) and 8 (b), the opening window 26 for positioning recognition of the FPC 20 has a portion of the cover layer 24 formed simultaneously with the formation of the opening 25 for electrical connection of the cover layer 24. It is composed of a through-hole drilled in a cross shape. The opening window portion 26 has a shape different from that of the dummy electrode pad portion 17b, and is arranged at the same pitch as the opening portion 25 for electrical bonding. By visually observing through the opening window 26, it is possible to inspect the bonding state between the plurality of piezoelectric elements 13 and the plurality of solder bumps 21 of the FPC 20.

  FIG. 9A and FIG. 9B show another modification 2 of the FPC according to the first embodiment. FIG. 9A is a partial cross-sectional view of the FPC, and FIG. 9B is a partial plan view of the FPC. In these figures, the difference from the first modification shown in FIGS. 8 (a) and 8 (b) is that an opening window in which a part of the cover layer 24 of the FPC 20 is perforated in a rectangular shape as a second alignment mark. This is in that a cover layer left in a cross shape is left in the portion 26. Therefore, in these drawings, substantially the same members as those of the first modification are given the same member names and symbols.

  9A and 9B, a cross-shaped uncut portion 24 a that is a second alignment mark is formed in the opening window portion 26 of the cover layer 24. Even in the second modification, whether the solder bumps 21 of the FPC 20 are securely soldered by visual observation through the opening window 26 for positioning recognition of the cover layer 24 of the FPC 20 after the piezoelectric element 13 and the FPC 20 are mounted. It can be inspected. In the second modification, since a through hole larger than the alignment mark of the dummy electrode pad portion 17b is formed corresponding to the pitch of the dummy electrode pad portion 17b, alignment can be performed easily. Further, even before the piezoelectric element 13 and the FPC 20 are mounted, the piezoelectric element 13 and the FPC 20 can be easily aligned.

  In the first embodiment, the positioning recognition opening window 26 different from the electrical bonding opening 25 of the cover layer 24 of the FPC 20 is configured as the second alignment mark. Is not limited to this. In the present invention, for example, the electrical bonding opening 25 can be used as a second alignment mark for aligning with the piezoelectric element 13, for example. By providing the cover layer 24 of the FPC 20 with the opening portion 25 for electrical connection and the opening window portion 26 for positioning recognition, the solder bump 21 of the FPC 20 can be surely mounted before or after mounting the piezoelectric element 13 and the FPC 20. It can be easily inspected whether or not it is soldered.

[Modification of pressure generating element]
FIG. 10A is a partial plan view schematically showing Modification 3 of the pressure generating element according to the first embodiment, and FIG. 10B is a portion taken along the line XB in FIG. 10A. An enlarged view and FIG. 10C are partial enlarged views of the XC line of FIG. 10A. In these figures, the main difference from the first embodiment is that the dummy region 16 that is not used for ejecting the liquid droplets is excluded, and the dummy electrode pad portion 17b of the dummy piezoelectric element 17 has the first feature. The first alignment mark is formed on the extended end portion 13c of the electrode pad portion 13b of the piezoelectric element 13 instead of the configuration for forming the alignment mark. Accordingly, in these drawings, substantially the same members as those in the first embodiment are given the same member names and reference numerals.

  10 (a) and 10 (b), the electrode pad portion 13b of the piezoelectric element 13 is integrally formed with an extended end portion 13c made of a rectangular plate having a cross shape on the same plane. The extended end portion 13c is configured as a first alignment mark (positioning mark) for positioning and joining the FPC 20 to a regular position. As this first alignment mark, as shown in FIGS. 10 (a) and 10 (c), an extended end portion 13d having a cross-shaped notch drilled in a rectangular flat plate material can be used. . Further, as another example of the first alignment mark, for example, an arbitrary form such as a rectangle, a triangle or a circular slit formed in the extended end portion 13d, or a through hole can be used.

  Even in the third modified example, the cover layer 24 of the FPC 20 has the piezoelectric element 13 and the eyes at positions corresponding to the extended end portions 13c and 13d of the piezoelectric element 13, as in the first embodiment. An opening window portion 26 for positioning recognition for alignment is formed integrally with the formation of the opening portion 25 for electrical connection. The opening window 26 has a shape different from or the same as the extended end portions 13c and 13d of the piezoelectric element 13, and is arranged with the same pitch as the center of the extended end portions 13c and 13d. Is preferred. As a result, the first alignment mark of the piezoelectric element 13 is visually confirmed through the opening window 26 of the FPC 20 or is confirmed by optical detection, and the piezoelectric elements 13 and the FPC 20 having the matrix arrangement structure are collectively collected. Thus, the bonding state between the plurality of piezoelectric elements 13 and the plurality of solder bumps 21 of the FPC 20 can be inspected by visual observation through the opening window portion 26.

(Effects of the first embodiment)
According to the first embodiment, the following effects can be obtained.
(A) Since the solder bumps 21 are provided in the electrical bonding openings 25 of the cover layer 24, the distance between the bump land portions 23b of the wiring pattern 23 and the wirings 23a can be shortened. As a result, a high-density wiring pattern 23 can be formed between adjacent bump land portions 23b.
(B) The high density mounting of the head body 10 can be achieved in combination with the fact that a high density wiring region can be obtained while securing the wiring area of the wiring pattern 23.
(C) The head body 10 and the FPC 20 can be bonded together with high accuracy.
(D) The second alignment mark can be integrally formed simultaneously with the formation of the electrical bonding opening 25 of the cover layer 24, and the first alignment mark can be integrally formed simultaneously with the formation of the piezoelectric element 13. Since it can be formed, various alignment marks can be formed easily and accurately.

[Second Embodiment]
(Color printer configuration)
FIG. 11 is a configuration diagram of a color printer to which the liquid droplet ejection apparatus according to the second embodiment of the present invention is applied. In FIG. 11, reference numeral 100 indicates a color printer according to the second embodiment. The color printer 100 has a substantially box-shaped casing 101. A paper feed tray 50 that accommodates the paper P is disposed in the lower portion of the housing 101, and a paper discharge tray 31 that ejects the recorded paper P is disposed in the upper portion of the housing 101. Further, the color printer 100 passes along main conveyance paths 31a to 31e from the paper tray 20 via the recording position 102 to the paper discharge tray 31 and a reverse conveyance path 32 from the paper discharge tray 31 side to the recording position 102 side. Conveying means 30 for conveying the paper P is provided.

  At the recording position 102, a plurality of droplet discharge heads 1 shown in FIG. 1 are arranged in parallel to form a droplet discharge head unit, and the four droplet discharge head units are arranged in yellow (Y), magenta (M), As a droplet discharge head unit 41 (41Y, 41M, 41C, 41K) that discharges ink droplets of each color of cyan (C) and black (K), the droplet discharge head array is configured by arranging in the paper P transport direction. ing.

  The color printer 100 includes a charging roll 43 as an adsorbing unit that adsorbs the paper P, a platen 44 disposed to face the liquid droplet ejection head units 41Y, 41M, 41C, and 41K via the endless belt 35, and liquid droplets. The maintenance unit 45 disposed in the vicinity of the discharge head units 41Y, 41M, 41C, and 41K and each part of the color printer 100 are controlled, and the droplet discharge head units 41Y, 41M, 41C, and 41K are controlled based on image signals. A control unit (not shown) that records a color image on the paper P by applying a driving voltage to the piezoelectric element 8 of the liquid droplet discharge head 1 to discharge the ink droplets from the nozzles 2a.

  The droplet discharge head units 41 </ b> Y, 41 </ b> M, 41 </ b> C, and 41 </ b> K have an effective print area that is equal to or larger than the width of the paper P. In the illustrated example, the piezoelectric method is used as a method for ejecting droplets. However, the method is not limited to the illustrated example, and a widely used method such as a thermal method can be used as appropriate.

  Above the droplet discharge head units 41Y, 41M, 41C, and 41K, ink tanks 42Y, 42M, 42C, and 42K that store ink of colors corresponding to the droplet discharge head units 41Y, 41M, 41C, and 41K are arranged. ing. Each ink tank 42Y, 42M, 42C, 42K is configured such that ink is supplied to each droplet discharge head 1 via a pipe (not shown). As the ink stored in the ink tanks 42Y, 42M, 42C, and 42K, various commonly used inks such as water-based, oil-based, and solvent-based inks can be appropriately used.

  The conveying means 30 is arranged in each part of the pick-up roll 33 that takes out the paper P one by one from the paper feed tray 50 and supplies it to the main conveying path 31a, the main conveying paths 31a, 31b, 31d, 31e, and the reverse conveying path 32. A plurality of transport rolls 34 that transport the paper P, an endless belt 35 that is provided at the recording position 102 and transports the paper P in the direction of the paper discharge tray 31, a drive roll 36 on which the endless belt 35 is stretched, and a follower A roll 37 and a drive motor (not shown) for driving the transport roll 34 and the drive roll 36 are provided.

(Color printer operation)
Next, the operation of the color printer 100 will be described. The transport unit 30 drives the pickup roll 33 and the transport roll 34 under the control of the control unit, takes out the paper P from the paper feed tray 50, and transports the paper P along the main transport paths 31a and 31b. When the paper P reaches the vicinity of the endless belt 35, electric charge is applied to the paper P by the electrostatic attraction force of the charging roll 43, and the paper P is attracted to the endless belt 35.

  The endless belt 35 is rotated by the drive of the drive roll 36, and when the paper P is conveyed to the recording position 102, a color image is recorded by the droplet discharge head units 41Y, 41M, 41C, 41K.

  That is, the liquid pool (not shown) of the droplet discharge head 1 shown in FIG. 1 is filled with the ink supplied from the ink tanks 42Y, 42M, 42C, and 42K, and the ink from the liquid pool passes through the supply holes and the supply paths. Is supplied to the pressure generation chamber 11, and ink is stored in the pressure generation chamber 11. When the control unit selectively applies a drive voltage to the plurality of piezoelectric elements 13 based on the image signal, the diaphragm 15 bends as the piezoelectric elements 13 are deformed. As a result, the volume in the pressure generating chamber 11 changes, and the ink stored in the pressure generating chamber 11 is ejected as ink droplets from the nozzles 12a onto the paper P through the communication holes, and an image is recorded on the paper P. . On the paper P, Y, M, C, and K images are sequentially overwritten, and a color image is recorded.

  The paper P on which the color image is recorded is discharged to the paper discharge tray 31 by the transport means 30 via the main transport path 31d.

  When the duplex recording mode is set, the paper P once discharged to the paper discharge tray 31 returns to the main transport path 31e again, passes through the reverse transport path 32, and again passes through the main transport path 31b. Then, the color image is recorded on the surface opposite to the surface of the paper P recorded last time by the droplet discharge head units 41Y, 41M, 41C, and 41K.

(Effect of the second embodiment)
According to the second embodiment described above, the following effects can be obtained.
(A) Since the droplet discharge head 1 is miniaturized, it is possible to achieve compactness and cost reduction.
(B) A color printer 100 in which a plurality of droplet discharge heads 1 are unitized by the head body 10 having a high-density wiring area can be obtained.

  The droplet discharge head and the droplet discharge device according to the present invention are not limited to the above embodiments and modifications, and various design changes can be made without departing from the spirit of the invention. is there. In each of the above embodiments and modifications, the flexible printed wiring board is used for connecting the piezoelectric element to the electrode layer. However, for example, a multilayer board may be used.

  The droplet ejection head and the droplet ejection apparatus of the present invention are required to form high-definition image information patterns by ejecting droplets, for example, an ink jet on a polymer film or a glass surface. Electrical and electronic industries, such as ejecting ink using a method to form display color filters, solder paste onto a substrate to form bumps for component mounting, and circuit board wiring It is effectively used in various fields such as the medical field for producing biochips for inspecting the reaction with a sample by discharging a reaction reagent onto a glass substrate or the like.

FIG. 2 is a cross-sectional view of main parts schematically showing main parts of the droplet discharge head according to the first embodiment of the present invention. It is a partial top view which shows roughly an example of the pressure generating element which is one structural component of a droplet discharge head. (A) is a partial plan view schematically showing an example of the structure of a wiring board that is one component of a droplet discharge head, and (b) is a cross-sectional view taken along line III-III in FIG. is there. (A)-(e) is explanatory drawing which shows the manufacturing process of a wiring board typically. (A)-(c) is explanatory drawing which shows typically the joining method of a wiring board and a pressure generation element. It is a fragmentary top view which shows typically the Example of the wiring pattern of the wiring board in 1st Embodiment. (A) is a partial top view which shows schematically the wiring pattern 23 of FPC20 of a comparative example, (b) is arrow sectional drawing of the VII-VII line of Fig.7 (a). (A) is a fragmentary sectional view which shows typically the modification 1 of the wiring board concerning 1st Embodiment, (b) is a partial top view of a wiring board. (A) is a fragmentary sectional view which shows typically the modification 2 of the wiring board concerning 1st Embodiment, (b) is a partial top view of a wiring board. (A) is the fragmentary top view which shows typically the modification 3 of the pressure generating element concerning 1st Embodiment, (b) is the elements on larger scale of the arrow XB line of FIG. 10 (a), ( c) is a partially enlarged view taken along line XC in FIG. It is a block diagram of the color printer which is the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Droplet discharge head 10 Head main body 11 Pressure generation chamber 12 Nozzle plate 12a Nozzle 13 Pressure generation element 13a Electrode drive part 13b Electrode pad part 13c, 13d Extension end part 14 Partition 15 Diaphragm 16 Droplet discharge area 17 Dummy piezoelectric element 17a Dummy electrode drive part 17b Dummy electrode pad part 18 Dummy area 20 Flexible printed circuit board (FPC)
21 Solder bump 21a Solder ball 22 Base layer 23 Wiring pattern 23a Wiring 23b Bump land 24 Cover layer 24a Uncut portion 25 Opening portion for electric connection 26 Opening window portion 30 Transport means 31 Paper discharge trays 31a to 31e Main transport path 32 Reverse Conveying path 33 Pickup roll 34 Conveying roll 35 Endless belt 36 Drive roll 37 Followed rolls 41Y, 41M, 41C, 41K Droplet discharge head units 42Y, 42M, 42C, 42K Ink tank 43 Charging roll 44 Platen 45 Maintenance unit 50 Paper feed tray 100 Color Printer 101 Case 102 Recording Position P Paper

Claims (9)

A liquid droplet ejection head for ejecting stored liquid as liquid droplets from a plurality of nozzles toward an ejection surface,
A head body having the plurality of nozzles, a plurality of pressure generating chambers communicating with the plurality of nozzles, and a plurality of pressure generating elements provided corresponding to the plurality of pressure generating chambers;
A base layer, a plurality of wiring patterns having bump land portions electrically connected to the wiring formed on the base layer, and a wiring board having a cover layer covering the plurality of wiring patterns,
The cover layer has a plurality of electrical bonding openings for electrically connecting the bump land portion of the wiring pattern and the pressure generating element via bumps,
The droplet discharge head, wherein the opening for electrical bonding is formed smaller than the bump land portion of the wiring pattern.   The droplet discharge head according to claim 1, wherein the bump land portion of the wiring pattern has a bump forming surface having the same size as the opening for electrical connection.   2. The droplet discharge head according to claim 1, wherein the bumps are formed by metal plating or solder balls.   The droplet discharge head according to claim 1, wherein the pressure generating elements are arranged in a matrix.   The pressure generating element has a first alignment mark for positioning, and has a second alignment mark at a position corresponding to the first alignment mark on the wiring board. 5. A droplet discharge head according to 1 or 4.   The pressure generating element has a plate-like piezoelectric element and a plate-like extension end formed on the piezoelectric element, and the first alignment mark is formed by the extension end. The droplet discharge head according to claim 5.   The cover layer of the wiring board has an opening window for positioning recognition at a portion corresponding to the pressure generating element, and the second alignment mark is formed by the opening window. The droplet discharge head according to claim 5.   8. The liquid droplet ejection head according to claim 7, wherein the second alignment mark is formed by an uncut portion of the cover layer remaining in the opening window portion. A liquid droplet ejection apparatus including a plurality of liquid droplet ejection heads that eject liquid as liquid droplets from a plurality of nozzles toward a surface to be ejected by driving a plurality of piezoelectric elements,
The droplet discharge head is
A head body having the plurality of nozzles, a plurality of pressure generating chambers communicating with the plurality of nozzles, and a plurality of pressure generating elements provided corresponding to the plurality of pressure generating chambers;
A base layer, a plurality of wiring patterns having bump land portions electrically connected to the wiring formed on the base layer, and a wiring board having a cover layer covering the plurality of wiring patterns,
The cover layer has a plurality of electrical bonding openings for electrically connecting the bump land portion of the wiring pattern and the pressure generating element via bumps,
The droplet discharge device, wherein the opening for electrical bonding is formed smaller than the bump land portion of the wiring pattern.

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