JP2008194985A - Manufacturing method of liquid ejection head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of liquid ejection head capable of preventing poor connection from occurring during wire bonding to a wiring pattern. <P>SOLUTION: In the manufacturing method of liquid ejection head having a flow channel forming substrate where a pressure generating chamber in communication with a nozzle opening for jetting droplets is formed, a piezoelectric element arranged in one face side of the flow channel forming substrate, a bonded substrate bonded to the flow channel forming substrate, and a wiring pattern connected to the piezoelectric element and arranged on the surface of the opposite side of the flow channel forming substrate of the bonding substrate, the wiring pattern 200 is formed by forming a plating metal layer 204 of a predetermined pattern on the surface of the bonding substrate 30 by plating, and the surface of the plating metal layer 204 is flattened by pressing the same by a predetermined pressure by a press member 250. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid ejecting head that ejects liquid, and more particularly, to a method for manufacturing an ink jet recording head that ejects ink as a liquid.

  A typical example of a liquid ejecting head that ejects droplets is an ink jet recording head that ejects ink droplets. As the ink jet recording head, for example, a flow path forming substrate in which a pressure generating chamber communicating with the nozzle opening and a communicating portion communicating with the pressure generating chamber are formed, and formed on one surface side of the flow path forming substrate. And a bonding substrate having a piezoelectric element holding portion bonded to the surface of the flow path forming substrate on the piezoelectric element side and holding the piezoelectric element, and driven on the bonding substrate via a wiring pattern Some ICs are mounted (see, for example, Patent Document 1).

  Further, such a wiring pattern on the bonding substrate is formed by electroless plating a material such as gold (Au).

JP 2004-148813 A

  By forming the wiring pattern by electroless plating in this way, the predetermined thickness can be achieved in a relatively short time. However, in the electroless plating method, since the bonding substrate is immersed in a large amount of plating solution, for example, it is difficult to maintain a constant ion concentration on the bonding substrate surface, and uneven plating, abnormal deposition, etc. on the wiring pattern surface are difficult. There is a problem that it occurs. In addition, when a convex portion is formed on the surface of the wiring pattern due to, for example, abnormal precipitation, for example, when the wiring pattern and the driving IC are wire-bonded, bonding defects on the wiring pattern side are caused. There is a risk that it will occur.

  Conventionally, in order to prevent such bonding failure, the convex portion on the surface of the wiring pattern is mechanically removed with a needle or the like, but there is a problem that the wiring pattern is damaged and defects such as disconnection occur. was there.

  Such a problem exists not only in a method for manufacturing an ink jet recording head that discharges ink, but also in a method for manufacturing another liquid ejecting head that discharges liquid other than ink.

  SUMMARY An advantage of some aspects of the invention is that it provides a method for manufacturing a liquid jet head capable of preventing a connection failure from occurring during wire bonding to a wiring pattern. Objective.

The present invention that solves the above-described problems includes a flow path forming substrate in which a pressure generation chamber communicating with a nozzle opening for ejecting droplets is formed, a piezoelectric element provided on one side of the flow path forming substrate, and the flow A method of manufacturing a liquid jet head, comprising: a bonding substrate bonded to a path forming substrate; and a wiring pattern connected to the piezoelectric element on a surface opposite to the flow path forming substrate of the bonding substrate. The wiring pattern is formed by forming a plating metal layer having a predetermined pattern on the surface of the bonding substrate by plating, and the surface of the plating metal layer is flattened by pressing with a predetermined pressure by a press member. The method of manufacturing a liquid jet head characterized by the above.
In the present invention, the surface of the plated metal layer, that is, the surface of the wiring pattern is flattened satisfactorily. Therefore, for example, by bonding wires, it is possible to connect the wiring to the wiring pattern satisfactorily.

  Here, in this invention, the convex part which consists of the same material as the said plating metal layer formed in the surface of the said plating metal layer is planarized by pressurizing the surface of the said plating metal layer with a press member. Therefore, the wiring pattern (plated metal layer) can be satisfactorily formed even when planarized.

  In the present invention, the step of forming the piezoelectric element on one surface side of the flow path forming substrate, the step of bonding the bonding substrate on which the wiring pattern is formed to the flow path forming substrate, and the flow path Forming the pressure generating chamber on the formation substrate, and in the step of bonding the bonding substrate to the flow path formation substrate, the bonding substrate is bonded by pressurizing the bonding substrate toward the flow path formation substrate by a press member. In addition, the surface of the plated metal layer may be flattened. As a result, the surface of the plated metal layer can be satisfactorily flattened and the manufacturing process can be simplified.

  The plated metal layer is preferably made of gold. Thereby, a plating metal layer can be formed comparatively favorable, and the surface can be planarized satisfactorily.

  Further, when a plurality of the bonding substrates are integrally formed on a bonding substrate wafer made of a silicon wafer, when the surface of the plating metal layer is planarized, the bonding substrate is formed on the bonding substrate wafer. It is preferable to pressurize the plating metal layer with a load of 50 to 300 (kgf). By applying a predetermined load in this way, the surface of the plated metal layer can be more reliably flattened while preventing the bonded substrate from cracking.

  A drive circuit for driving the piezoelectric element is mounted on the wiring pattern, and the drive circuit and the wiring pattern are electrically connected by wire bonding. Since the surface of the wiring pattern is flattened as described above, the drive circuit and the wiring pattern can be reliably connected by wire bonding.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
1 is an exploded perspective view of an ink jet recording head manufactured by a manufacturing method according to Embodiment 1 of the present invention, and FIG. 2 is a plan view and a cross-sectional view of FIG.

  As shown in the figure, the flow path forming substrate 10 is a silicon single crystal substrate having a crystal plane orientation of (110) in this embodiment, and an elastic film 50 made of an oxide film is formed on one surface thereof. In the flow path forming substrate 10, a plurality of pressure generating chambers 12 partitioned by a partition wall 11 are arranged in parallel in the width direction.

  Further, an ink supply path 13 and a communication path 14 that are partitioned by a partition wall 11 and communicate with each pressure generation chamber 12 are provided on one end side in the longitudinal direction of the pressure generation chamber 12 of the flow path forming substrate 10. Furthermore, a communication portion 15 that communicates with each communication path 14 is provided outside the communication path 14. The communication portion 15 communicates with a reservoir portion 32 of the bonding substrate 30 to be described later, and constitutes a part of the reservoir 100 serving as a common ink chamber (liquid chamber) for each pressure generating chamber 12.

  Here, the ink supply path 13 is formed to have a narrower cross-sectional area than the pressure generation chamber 12, and the flow path resistance of the ink flowing into the pressure generation chamber 12 from the communication portion 15 is kept constant. . For example, in this embodiment, the ink supply path 13 has a width smaller than the width of the pressure generation chamber 12 by narrowing the flow path on the pressure generation chamber 12 side between the reservoir 100 and each pressure generation chamber 12 in the width direction. It is formed with. In this embodiment, the ink supply path is formed by narrowing the width of the flow path from one side. However, the ink supply path may be formed by narrowing the width of the flow path from both sides. Further, the ink supply path may be formed by narrowing from the thickness direction instead of narrowing the width of the flow path. Each communication path 14 is formed by extending the partition walls 11 on both sides in the width direction of the pressure generating chamber 12 to the communication part 15 side to partition the space between the ink supply path 13 and the communication part 15.

  As a material for the flow path forming substrate 10, a silicon single crystal substrate is used in the present embodiment. However, the material is not limited to this, and glass ceramics, stainless steel, etc. may be used.

  A nozzle plate 20 in which a plurality of nozzle openings 21 are formed is fixed to the opening surface side of the flow path forming substrate 10 by, for example, an adhesive or a heat welding film. The generation chamber 12 communicates with the vicinity of the end opposite to the ink supply path 13. The nozzle plate 20 is made of, for example, glass ceramics, a silicon single crystal substrate, stainless steel, or the like.

  On the other hand, the elastic film 50 is formed on the surface opposite to the opening surface of the flow path forming substrate 10 as described above. The elastic film 50 is made of an oxide film made of a material different from that of the elastic film 50. An insulator film 55 is formed. Further, a piezoelectric element 300 including a lower electrode film 60, a piezoelectric layer 70 having a thickness of, for example, about 0.5 to 5 μm, and an upper electrode film 80 is formed on the insulator film 55. ing. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80. In general, one of the electrodes of the piezoelectric element 300 is used as a common electrode, and the other electrode is patterned together with the piezoelectric layer 70 for each pressure generating chamber 12 to form individual electrodes. Here, the piezoelectric element 300 and the vibration plate that is displaced by driving the piezoelectric element 300 are collectively referred to as an actuator device. In the above-described example, the elastic film 50, the insulator film 55, and the lower electrode film 60 substantially function as a vibration plate, but only the lower electrode film 60 is provided without providing the elastic film 50 and the insulator film 55. The lower electrode film 60 may be left as a diaphragm. Further, the piezoelectric element 300 itself may substantially serve as a diaphragm. Further, a lead electrode 90 made of, for example, gold (Au) or the like is connected to the upper electrode film 80 of each piezoelectric element 300, and is selectively connected to each piezoelectric element 300 via the lead electrode 90. A voltage is applied to.

  On the flow path forming substrate 10 on which such a piezoelectric element 300 is formed, a bonding substrate 30 having a piezoelectric element holding portion 31 for bonding the piezoelectric element 300 is bonded by, for example, an adhesive layer 35. Note that the space defined by the piezoelectric element holding portion 31 may be sealed or may not be sealed. Further, the bonding substrate 30 is provided with a reservoir portion 32 that constitutes at least a part of the reservoir 100 in which the ink supplied to the plurality of pressure generating chambers 12 is stored. In the present embodiment, the reservoir portion 32 is formed across the bonding substrate 30 in the thickness direction and across the width direction of the pressure generating chamber 12. As described above, the communication portion 15 of the flow path forming substrate 10. The reservoir 100 is configured to be communicated with each other. Note that the communication portion 15 of the flow path forming substrate 10 may be divided into a plurality for each pressure generation chamber 12 and only the reservoir portion 32 may be used as the reservoir. Further, for example, only the pressure generating chamber 12 is provided in the flow path forming substrate 10, and the reservoir (member such as the elastic film 50, the insulator film 55, etc.) interposed between the flow path forming substrate 10 and the bonding substrate 30 is provided with the reservoir. An ink supply path 13 that communicates with each pressure generation chamber 12 may be provided.

  As such a bonding substrate 30, it is preferable to use a material substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10, for example, a glass material, a ceramic material or the like. A silicon single crystal substrate as a material is used.

  Further, the bonding substrate 30 is provided with a through hole 33 that penetrates the bonding substrate 30 in the thickness direction, and the vicinity of the end portion of the lead electrode 90 drawn from each piezoelectric element 300 is in the through hole 33. Exposed. In addition, a wiring pattern 200 including a plurality of wirings is formed on the bonding substrate 30, and a driving circuit 210 for driving the plurality of piezoelectric elements 300, such as a circuit board, is formed on the wiring pattern 200. A semiconductor integrated circuit (IC) or the like is fixed. The drive circuit 210 and the lead electrode 90 are electrically connected by a first connection wiring 220 made of a conductive wire such as a bonding wire extending in the through hole 33. Further, the drive circuit 210 and the wiring pattern 200 are electrically connected by a second connection wiring 230 made of a conductive wire such as a bonding wire. The pattern shape of the wiring pattern 200 is not particularly limited.

  In addition, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the bonding substrate 30. Here, the sealing film 41 is made of an organic material having low rigidity and flexibility, and one surface of the reservoir portion 32 is sealed by the sealing film 41. The fixing plate 42 is made of a hard material such as metal. A region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, and one surface of the reservoir 100 is sealed only with a flexible sealing film 41. ing.

  In such an ink jet recording head of this embodiment, ink is taken in from an ink introduction port connected to an external ink supply means (not shown), and the interior from the reservoir 100 to the nozzle opening 21 is filled with ink, and then the drive circuit 210 is filled. In accordance with the recording signal from, pressure is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generation chamber 12 to bend and deform the piezoelectric element 300, whereby the pressure in each pressure generation chamber 12 is changed. And the ink droplets are ejected from the nozzle openings 21.

  Hereinafter, a method for manufacturing such an ink jet recording head will be described with reference to FIGS. 3, 4, and 7 are cross-sectional views in the longitudinal direction of the pressure generation chamber, and FIGS. 5 and 6 are cross-sectional views in the width direction of the pressure generation chamber.

  A piezoelectric element is formed on one side of a flow path forming substrate wafer 110 which is a silicon wafer and in which a plurality of flow path forming substrates 10 are integrally formed.

  First, as shown in FIG. 3A, a first oxide film that constitutes an elastic film 50 on the surface of a flow path forming substrate wafer 110 that is a silicon wafer and in which a plurality of flow path forming substrates 10 are integrally formed. 51 is formed. Next, as illustrated in FIG. 3B, an insulator film 55, which is a second oxide film made of a material different from the first oxide film 51, is formed on the elastic film 50.

  Next, as shown in FIG. 3C, after forming the lower electrode film 60 on the insulator film 55, the lower electrode film 60 is patterned into a predetermined shape. Next, as shown in FIG. 3D, for example, a piezoelectric layer 70 made of lead zirconate titanate (PZT) or the like and an upper electrode film 80 are formed on the entire surface of the flow path forming substrate wafer 110. Then, the piezoelectric layer 300 and the upper electrode film 80 are patterned in a region facing each pressure generating chamber 12 to form the piezoelectric element 300.

  Next, as shown in FIG. 3E, lead electrodes 90 are formed. Specifically, first, an adhesion layer 91 is formed over the entire surface of the flow path forming substrate wafer 110, and a metal layer 92 is formed on the adhesion layer 91. Then, a mask pattern (not shown) made of, for example, a resist is formed on the metal layer 92, and the metal layer 92 and the adhesion layer 91 are patterned for each piezoelectric element 300 through the mask pattern, thereby leading to the lead electrode. 90 is formed.

  On the other hand, a wiring pattern 200 is formed on a bonding substrate wafer 130 on which a plurality of bonding substrates 30 are integrally formed. Note that the piezoelectric element holding portion 31, the reservoir portion 32, and the through hole 33 are formed in advance in the bonding substrate wafer 130 by, for example, anisotropic etching.

  Specifically, first, as shown in FIG. 4A, an adhesion layer made of nickel chromium (NiCr) and having a thickness of about 20 [nm] is formed on the entire surface of the bonding substrate wafer 130 by, for example, sputtering. 201 and a metal layer 202 made of gold (Au) and having a thickness of about 200 [nm] are formed. Next, as shown in FIG. 4B, the metal layer 202 and the adhesion layer 201 are sequentially patterned by photolithography to form a base metal layer 203 having a predetermined shape. Next, as shown in FIG. 4C, a plated metal layer 204 made of gold (Au) and having a thickness of about 1 mm is formed on the base metal layer 203 (metal layer 202) by, for example, electroless plating. Form. That is, the plated metal layer 204 is formed by depositing gold (Au) on the metal layer 202 to form the wiring pattern 200. At this time, as shown in FIG. 5 which is a BB ′ cross-sectional view of FIG. 4C, gold (Au) is abnormally deposited on the surface of the plated metal layer 204 or gold (Au). The convex part 205 will be formed because a foreign material adheres. In addition, although the same material as the material of the metal layer 202, that is, gold (Au) foreign matter may adhere to the surface of the plated metal layer 204, almost all foreign matter made of a material different from the metal layer 202 adheres. Never do.

  Next, the bonding substrate wafer 130 having the wiring pattern 200 formed on the surface as described above is formed on the flow path forming substrate wafer 110, for example, an epoxy-based adhesive or the like, as shown in FIG. It joins through the adhesive layer 35 which consists of. Specifically, the bonding substrate wafer 130 is placed on the flow path forming substrate wafer 110 via the adhesive layer 35, and is formed on the bonding substrate wafer 130 as shown in FIG. The surface of the wiring pattern 200 is pressed with a predetermined pressure to the flow path forming substrate wafer 110 side by a pressing member 250 made of, for example, a metal plate. Thereby, the bonding substrate wafer 130 is pressure-bonded to the flow path forming substrate wafer 110, and at the same time, the surface of the wiring pattern 200 (plated metal layer 204) is flattened (FIG. 6C).

  Thus, the pressure for pressing the surface of the wiring pattern 200 by the press member 250 may be a pressure that does not break the bonding substrate wafer 130, the flow path forming substrate wafer 110, etc., for example, 50 to 300 [kgf It is preferable to set the pressure to a degree. Thereby, the surface of the wiring pattern 200 (plated metal layer 204) can be satisfactorily flattened, and the bonding substrate wafer 130 and the flow path forming substrate wafer 110 can be bonded well.

  Next, as shown in FIG. 7A, after the flow path forming substrate wafer 110 is thinned to a certain thickness, as shown in FIG. 7B, on the flow path forming substrate wafer 110, for example, A protective film 52 is newly formed and patterned into a predetermined shape. Then, as shown in FIG. 8A, the flow path forming substrate wafer 110 is anisotropically etched (wet etching) using the protective film 52 as a mask, and the pressure generating chamber 12 is applied to the flow path forming substrate wafer 110. The ink supply path 13, the communication path 14, and the communication part 15 are formed. That is, the flow path forming substrate wafer 110 is etched by using an etchant such as an aqueous potassium hydroxide (KOH) solution until the elastic film 50 is exposed. Etc. are formed simultaneously. Further, the elastic film 50 and the insulator film 55 are removed, and the communication part 15 and the reservoir part 32 are communicated.

  Next, as shown in FIG. 8B, the driving circuit 210 is mounted on the wiring pattern 200 formed on the bonding substrate wafer 130, and the driving circuit 210, the lead electrode 90, and the wiring pattern 200 are wire-bonded. Electrically connect with. That is, the drive circuit 210 and the lead electrode 90 are connected by the first connection wiring 220, and the drive circuit 210 and the wiring pattern 200 are connected by the second connection wiring 230.

  At this time, since the surface of the wiring pattern 200 is flattened as described above, the second connection wiring 230 is satisfactorily connected to the wiring pattern 200 without causing bonding failure. Therefore, a highly reliable ink jet recording head can be manufactured without causing a connection failure or the like.

  After that, unnecessary portions of the outer peripheral edge portions of the flow path forming substrate wafer 110 and the bonding substrate wafer 130 are removed by cutting, for example, by dicing. The nozzle plate 20 having the nozzle openings 21 is bonded to the surface of the flow path forming substrate wafer 110 opposite to the bonded substrate wafer 130, and the compliance substrate 40 is bonded to the bonded substrate wafer 130. To do. Then, by dividing the flow path forming substrate wafer 110, the bonding substrate wafer 130 and the like into a single chip size flow path forming substrate 10 as shown in FIG. Is done.

(Other embodiments)
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above. For example, in the above-described embodiment, when the bonding substrate wafer is bonded to the flow path forming substrate wafer, the surface of the wiring pattern formed on the bonding substrate wafer is simultaneously flattened. In addition to the bonding step of bonding the path forming substrate wafer and the bonding substrate wafer, a flattening step of pressing and flattening the surface of the wiring pattern may be performed.

  In this case, the wiring pattern 200 on the bonding substrate 30 connected to the bonding pad on the driving circuit 210 via the second connection wiring 230 is formed in a region not facing the piezoelectric element holding portion 31 of the bonding substrate 30. Is preferred. The ink supply path 13 is preferably formed in a region of the flow path forming substrate 10 facing the wiring pattern 200. By doing in this way, the wiring pattern 200 is an area | region where the board thickness of the joining board | substrate 30 is thick, and the flow path formation board | substrate 10 is also formed in an area | region where rigidity is high. Therefore, even if the pressure to pressurize the wiring pattern 200 is increased, the surface of the wiring pattern 200 can be more reliably flattened without cracking the bonding substrate 30 and the flow path forming substrate 10.

  Further, when a planarization step is performed separately from the bonding step, the planarization step may be performed before the bonding substrate wafer is bonded to the flow path forming substrate wafer or after the bonding. May be. In any case, the planarization process may be performed before mounting the drive circuit on the wiring pattern.

  In the above-described embodiment, an ink jet recording head has been described as an example of a liquid ejecting head. However, the present invention is widely intended for all liquid ejecting heads and ejects liquids other than ink. Of course, the present invention can also be applied to a method of manufacturing a liquid jet head. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

FIG. 3 is an exploded perspective view of the recording head according to the first embodiment. 2A and 2B are a plan view and a cross-sectional view of the recording head according to the first embodiment. 5 is a cross-sectional view showing a manufacturing process according to Embodiment 1. FIG. 5 is a cross-sectional view showing a manufacturing process according to Embodiment 1. FIG. It is sectional drawing which shows the surface state of a wiring pattern typically. 5 is a cross-sectional view showing a manufacturing process according to Embodiment 1. FIG. 5 is a cross-sectional view showing a manufacturing process according to Embodiment 1. FIG. 5 is a cross-sectional view showing a manufacturing process according to Embodiment 1. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 12 Pressure generation chamber, 13 Ink supply path, 14 Communication path, 15 Communication part, 20 Nozzle plate, 21 Nozzle opening, 30 Bonding board, 31 Piezoelectric element holding part, 32 Reservoir part, 40 Compliance board, 50 elastic film, 55 insulator film, 60 lower electrode film, 70 piezoelectric layer, 80 upper electrode film, 90 lead electrode, 91 adhesion layer, 92 metal layer, 95 discontinuous metal layer, 100 reservoir, 110 flow path forming substrate Wafer, 130 bonding substrate wafer, 200 wiring pattern, 210 drive circuit, 220 first connection wiring, 230 second connection wiring, 250 press member, 300 piezoelectric element

Claims (6)

A flow path forming substrate in which a pressure generation chamber communicating with a nozzle opening for ejecting liquid droplets is formed, a piezoelectric element provided on one surface side of the flow path forming substrate, and a bonding substrate bonded to the flow path forming substrate And a manufacturing method of a liquid ejecting head provided with a wiring pattern connected to the piezoelectric element on a surface of the bonding substrate opposite to the flow path forming substrate,
The wiring pattern is formed by forming a plating metal layer having a predetermined pattern by plating on the surface of the bonding substrate, and the surface of the plating metal layer is flattened by pressurizing with a press member with a predetermined pressure. A method for manufacturing a liquid jet head.   The convex part which consists of the same material as the said plating metal layer formed in the surface of the said plating metal layer is planarized by pressurizing the surface of the said plating metal layer with a press member. Manufacturing method of the liquid jet head of the present invention. Forming the piezoelectric element on one surface side of the flow path forming substrate, bonding the bonding substrate on which the wiring pattern is formed to the flow path forming substrate, and generating the pressure on the flow path forming substrate. Forming a chamber,
In the step of bonding the bonding substrate to the flow path forming substrate, the bonding substrate is bonded to the flow path forming substrate side by pressing with a press member, and the surface of the plated metal layer is flattened. The method of manufacturing a liquid jet head according to claim 1.   The method of manufacturing a liquid jet head according to claim 1, wherein the plated metal layer is made of gold.   When the bonding substrate is integrally formed on a bonding substrate wafer made of a silicon wafer and the surface of the plating metal layer is flattened, the plating metal layer formed on the bonding substrate wafer is 50 The method of manufacturing a liquid jet head according to claim 1, wherein pressurization is performed with a load of ˜300 (kgf).   6. A driving circuit for driving the piezoelectric element is mounted on the wiring pattern, and the driving circuit and the wiring pattern are electrically connected by wire bonding. A method for manufacturing a liquid jet head according to claim 1.

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