Inkjet head and method of manufacturing the same

Abstract

An inkjet head (100) comprises: a nozzle plate (20) having a plurality of nozzle holes (21) for ejecting ink; a partition wall (15) that separates a plurality of pressure chambers (155) communicating with each of the plurality of nozzle holes (21); a diaphragm (14) forming one surface of the plurality of pressure chambers (155); and piezoelectric elements (11) each being in contact with the diaphragm (14) on the outside of the plurality of ink chambers. The amount of deviation of the position where the wall surface of the pressure chamber (155) of the partition wall portion (15) is in contact with the diaphragm (14) from a predetermined reference position is not more than 1.0% of the reference width of the plurality of pressure chambers (155).

Description

[Technical field]

[0001] The present invention relates to an inkjet head and a method for manufacturing an inkjet head. [Background technology]

[0002] There are inkjet heads that have many nozzles, each of which ejects ink. The ink is ejected by applying pressure fluctuations to the ink stored in a pressure chamber that communicates with the nozzles. Some inkjet heads are equipped with a piezoelectric element that deforms the wall of the pressure chamber, and eject ink at an amount and speed that corresponds to the amount of deformation by applying a voltage to the piezoelectric element that corresponds to the desired amount of deformation.

[0003] In order to accurately determine the speed and amount of ink to be ejected, each part needs to be formed accurately. Patent Document 1 discloses a technique in which the partitions that separate the multiple pressure chambers and the contact parts of the diaphragm that vibrates in response to the deformation of the piezoelectric element are made of the same main component, and the partitions are formed by electroplating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-045871 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, forming the partition walls by electroplating requires a resist pattern with a very large thickness, which makes it difficult to obtain sufficient precision in the resist pattern, and thus poses the problem that the ink ejection characteristics tend to vary.

[0006] An object of the present invention is to provide an ink-jet head capable of ejecting ink more accurately and stably, and a method for manufacturing the ink-jet head. [Means for solving the problem]

[0007] In order to achieve the above object, the invention described in claim 1 comprises: a nozzle plate having a plurality of nozzle holes for ejecting ink; a partition wall portion separating a plurality of ink chambers each of which communicates with the plurality of nozzle holes; a vibration plate forming one surface of the ink chambers; a piezoelectric element in contact with an outer side of each of the ink chambers of the vibration plate; Equipped with a deviation amount of a position where a wall surface of the ink chamber of the partition portion contacts the vibration plate from a predetermined reference position is 1.0% or less with respect to a reference width of the plurality of ink chambers, the nozzle plate defines a surface of the ink chamber facing the vibration plate, the partition is made of metal; The ink chamber is arranged in a height direction from the nozzle plate side to the vibration plate side. The shape of the cross section perpendicular to the height direction is uniform and the cross section is having a plurality of regions that differ from one another in size or shape; The height of the region closest to the diaphragm is smallest among the plurality of regions. It is an inkjet head.

[0011] Also, claims 2 The invention described is as follows: 1 In the inkjet head described above, The metal includes at least nickel.

[0012] Also, claims 3 The invention described is as follows: 1 or 2 In the inkjet head described above, The partition portion is an electroplated thick film.

[0013] Also, claims 4 The invention described is a first forming step of sequentially forming, on a substrate, a first conductive film, a piezoelectric film, an insulating pattern having openings corresponding to the plurality of ink chambers, and a diaphragm layer including a second conductive film; a second forming step of forming, by plating, a partition wall portion that separates the ink chambers each including the first region and the second region, by defining a first region by a first plating resist pattern inside the opening portion in a plan view seen from a direction perpendicular to the substrate, and defining a second region by a second plating resist pattern in a range including at least a portion of the defined first region; a third forming step of forming piezoelectric elements corresponding to the ink chambers by pattern-etching the first conductive film and the piezoelectric film after removing the substrate; The present invention relates to a method for manufacturing an inkjet head,

[0014] Also, claims 5 The invention described is as follows: 4 In the method for producing an inkjet head according to the present invention, In the second forming step, a first layer of the partition wall is formed around the defined first region, and then a second layer of the partition wall is formed around the defined second region.

[0015] Also, claims 6 The invention described is as follows: 4 In the method for producing an inkjet head according to the present invention, In the second formation step, a negative-type second resist film is formed on a negative-type first resist film to which the range of the first plating resist pattern has been exposed, and an area included in the range of the first plating resist pattern in a planar view is exposed as the range of the second plating resist pattern, and the partition portion is formed in the portion not covered by either the developed first plating resist pattern or the developed second plating resist pattern.

[0016] Also, claims 7 The invention described is as follows: 4 In the method for producing an inkjet head according to the present invention, In the second formation step, a positive type second resist film is formed on a positive type first resist film that has been exposed while leaving the area of ​​the first plating resist pattern, and the second resist film is exposed while leaving an area that includes the area of ​​the first plating resist pattern in a planar view as the area of ​​the second plating resist pattern, and the partition portion is formed in the portion that is not covered by either the developed first plating resist pattern or the developed second plating resist pattern.

[0017] Also, claims 8 The invention described is as follows: 4~7 13. The method for producing an inkjet head according to claim 12, The first plating resist pattern and the second plating resist pattern are formed of a dry film resist. Effect of the Invention

[0018] According to the present invention, it is possible to obtain an effect that ink can be ejected from an ink-jet head more accurately and stably. [Brief description of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view showing a structure of an inkjet head according to an embodiment of the present invention. [Figure 2A] 5A and 5B are diagrams illustrating a boundary portion between a partition portion and a diaphragm. [Figure 2B] 5A and 5B are diagrams illustrating a boundary portion between a partition portion and a diaphragm. [Figure 2C] 5A and 5B are diagrams illustrating a boundary portion between a partition portion and a diaphragm. [Figure 3A] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 3B] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 3C] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 4A] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 4B] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 4C] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 4D] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 5A] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 5B] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 5C] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 5D] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 6A] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 6B] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 6C] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 7A] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 7B] 5A to 5C are cross-sectional views illustrating a manufacturing process of the inkjet head. [Figure 8A] 10 is a cross-sectional view showing a first modified example of a part of the method for manufacturing an inkjet head. [Figure 8B] 10 is a cross-sectional view showing a first modified example of a part of the method for manufacturing an inkjet head. [Figure 8C] 10 is a cross-sectional view showing a first modified example of a part of the method for manufacturing an inkjet head. [Figure 8D] 10 is a cross-sectional view showing a first modified example of a part of the method for manufacturing an inkjet head. [Figure 9A] 10 is a cross-sectional view showing a first modified example of a part of the method for manufacturing an inkjet head. [Figure 9B] 10 is a cross-sectional view showing a first modified example of a part of the method for manufacturing an inkjet head. [Figure 9C]10 is a cross-sectional view showing a first modified example of a part of the method for manufacturing an inkjet head. [Figure 10A] 11 is a cross-sectional view showing a second modified example of a part of the method for manufacturing an inkjet head. FIG. [Figure 10B] 11 is a cross-sectional view showing a second modified example of a part of the method for manufacturing an inkjet head. FIG. [Figure 10C] 11 is a cross-sectional view showing a second modified example of a part of the method for manufacturing an inkjet head. FIG. [Figure 10D] 11 is a cross-sectional view showing a second modified example of a part of the method for manufacturing an inkjet head. FIG. [Figure 11A] 11 is a cross-sectional view showing a second modified example of a part of the method for manufacturing an inkjet head. FIG. [Figure 11B] 11 is a cross-sectional view showing a second modified example of a part of the method for manufacturing an inkjet head. FIG. [Figure 11C] 11 is a cross-sectional view showing a second modified example of a part of the method for manufacturing an inkjet head. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a cross-sectional view showing the structure of an inkjet head 100 according to this embodiment. Although only a portion corresponding to one nozzle hole 21 is shown here, the inkjet head 100 has a plurality of nozzle holes 21, which are arranged at appropriate intervals and in an appropriate arrangement pattern.

[0021] The inkjet head 100 includes a piezoelectric element 11, an insulating pattern 13, a vibration plate 14, a partition portion 15, a protective film 16, a nozzle plate 20, and the like.

[0022] The nozzle plate 20 has nozzle holes 21 for ejecting ink. The material of the nozzle plate 20 is, for example, nickel (Ni), but is not limited to this. For example, the nozzle plate 20 may be SUS, a silicon (Si) substrate, or a silicon on insulator (SOI) substrate.

[0023] The area surrounded by the vibration plate 14, the partition wall portion 15 and the nozzle plate 20 forms a pressure chamber 155 (ink chamber). In the following, in accordance with FIG. 1, the vibration plate 14 is described as the upper surface (one surface) of the pressure chamber 155, the nozzle plate 20 is described as the lower surface of the pressure chamber 155, and the partition wall portion 15 is described as the side surface of the pressure chamber 155. Each pressure chamber 155 communicates with one of the nozzle holes 21 in the nozzle plate 20. In addition, in the direction perpendicular to the cross section of FIG. 1, there is an ink flow path (not shown) which communicates with the pressure chamber 155. The vibration plate 14 vibrates in the vertical direction of FIG. 1, thereby applying a pressure fluctuation to the ink in the pressure chamber 155.

[0024] The partition wall 15 separates the pressure chambers 155 from each other. Here, the partition wall 15 is a metal, for example, a Ni plating layer. Alternatively, the partition wall 15 may be an alloy of Ni and cobalt (Co), platinum (Pt), iron (Fe), or the like. The partition wall 15 made of these metals is, for example, an electroplated thick film. The partition wall 15 has a shape in which a plurality of (here, two) regions having different sizes or shapes of the pressure chambers 155, i.e., widths in the left-right direction of FIG. 1, overlap each other in the up-down direction (height direction). Here, the first region 1551 on the vibration plate 14 side (upper side) of the pressure chamber 155 is narrow (the gap of the first layer 151 of the partition wall 15 is narrow), and the second region 1552 on the nozzle plate 20 side (lower side) is wide (the gap of the second layer 152 of the partition wall 15 is wide), but is not limited thereto. Furthermore, the thickness of the first layer 151 (closest to the diaphragm 14) in the vertical direction is narrow (the thickness of the first region 1551 is the smallest), and the thickness of the second layer 152 may be determined appropriately according to the necessary thickness of the pressure chamber 155. The shape of the pressure chamber 155 is not particularly limited, and the first layer 151 and the second layer 152 may be cylindrical with the same center position. Alternatively, the pressure chamber 155 may have a shape in which a rectangular column portion is combined between semi-cylinders.

[0025] The vibration plate 14 has a laminated structure including a lower electrode layer 141, an insulating layer 142, and a Ni seed layer 143. The vibration plate 14 is located opposite the nozzle plate 20 with a pressure chamber 155 in between. The lower electrode layer 141 sandwiches the piezoelectric member 112 with the upper electrode 111, and deforms the piezoelectric member 112 according to the potential difference between the two electrodes. The lower electrode layer 141 is a conductive member, and examples of the material include chromium (Cr), titanium (Ti), Ni, iridium (Ir), platinum (Pt), copper (Cu), and gold (Au). The lower electrode layer 141 is a film-like structure that extends in common to the multiple piezoelectric members 112, and is a common electrode to which a common potential is applied.

[0026] The insulating layer 142 is, for example, a Si oxide layer or a resin layer, and electrically separates the lower electrode layer 141 from the partition wall 15. The Ni seed layer 143 serves as an electrode when the partition wall 15 is formed on the diaphragm 14 by electroplating as described below, and is a thin film layer for forming the partition wall 15 while appropriately adhering it.

[0027] The diaphragm 14 deforms and vibrates in response to the deformation of the piezoelectric element 11 (piezoelectric member 112). Since the partition portion 15 has a high rigidity, the vibration of the diaphragm 14 occurs at the edges of the partition portion 15 as nodes.

[0028] The insulating pattern 13 has an opening pattern corresponding to a range including a first region 1551 of the pressure chamber 155 in a plan view seen from above the inkjet head 100 (upper side in FIG. 1) perpendicular to the diaphragm 14 (substrate 50 described below) in a non-vibrating, non-deformed state. The insulating pattern 13 is, for example, a silicon oxide layer (SiO2) or various resin layers.

[0029] The piezoelectric element 11 has an upper electrode 111, a piezoelectric member 112, and a lower electrode layer 141. That is, the lower electrode layer 141 is included in both the piezoelectric element 11 and the diaphragm 14. The piezoelectric element 11 is in contact with the diaphragm 14 (the lower electrode layer 141 is the boundary), that is, the side of the diaphragm 14 opposite to the pressure chamber 155.

[0030] The piezoelectric members 112 deform in response to a voltage applied between the upper electrode 111 and the lower electrode layer 141. An example of the piezoelectric members 112 is PZT (lead zirconate titanate). The piezoelectric members 112 are each located within the opening pattern of the insulating pattern 13 and within a range that is included in the first region 1551 of the pressure chamber 155 in a plan view.

[0031] The upper electrodes 111 are conductive members located in contact with the upper side surfaces of the piezoelectric members 112, and are individual electrodes that apply a voltage to each piezoelectric member 112 individually. The upper electrodes 111 may have a similar shape that is approximately the same as or smaller than the piezoelectric members 112 in a plan view. The upper electrodes 111 are made of, for example, Ir or Pt. The shapes of the piezoelectric members 112 and the upper electrodes 111 may be, for example, disk shapes similar to the shape of the pressure chambers 155 and having the same center position.

[0032] The protective film 16 protects the piezoelectric members 112 and the upper electrode 111 of the inkjet head 100 by embedding therein the regions above the piezoelectric members 112 and between the piezoelectric members 112. The protective film 16 is made of, for example, a resin.

[0033] As described above, since the edge of the first layer 151 of the partition portion 15 becomes the node of vibration of the diaphragm 14, if the positional accuracy is low, the resonance frequency changes and accurate vibration is not generated. Therefore, in the manufacturing method of the inkjet head 100 of this embodiment, the edge of the first layer 151 of the partition portion 15 is determined with high accuracy.

[0034] 2A to 2C are diagrams illustrating the boundary portion between the partition portion 15 and the diaphragm 14. FIG. 2A and 2B, when etching is performed so as to leave a thick partition wall 15 on the pressure chamber substrate on the vibration plate 14, the side wall (wall surface) of the pressure chamber 155 of the partition wall 15 does not become a uniform flat surface up to the position (corner) where it contacts the vibration plate 14, and a skirt 1501 occurs due to uncut areas as shown in Fig. 2A, or a bottom narrowing 1502 occurs due to the side wall being cut too much along the bottom surface as shown in Fig. 2B. As a result, both ends of the vibration of the vibration plate 14 are shifted from the designed positions, and the vibration characteristics, i.e., the ink ejection characteristics for each nozzle, are not uniform.

[0035] In the inkjet head 100 of this embodiment, the partition 15 has a two-layer structure as described above (FIG. 2C), and the thickness of each layer, particularly the thickness of the first layer 151 in contact with the diaphragm 14, is made thinner than the overall thickness to improve the shape of the partition 15, particularly the accuracy of the position of the corners. That is, the deviation or variation of the corner position from the originally designed partition position n0 (predetermined reference position) is reduced, and thus the deviation of the distance between the partition positions at both ends from the distance (reference width) between the partition positions n0 at both ends is also reduced.

[0036] Next, a method for manufacturing the inkjet head 100 will be described. As described above, the edge of the first layer 151 of the partition portion 15 becomes the node of vibration of the diaphragm 14, so if the positional accuracy is low, the resonance frequency changes and accurate vibration is not generated. Therefore, in the manufacturing method for the inkjet head 100 of this embodiment, the edge of the first layer 151 of the partition portion 15 is determined with high accuracy.

[0037] 3A to 7B are cross-sectional views showing the manufacturing process of the inkjet head 100 of this embodiment. The cross sections are the same as the cross section of the inkjet head 100 shown in FIG.

[0038] 3A, first, a conductor layer 511 (first conductive film) is formed on a substrate 50, and then a piezoelectric layer 512 (piezoelectric film) is formed on the conductor layer 511. The conductor layer 511 is a portion that becomes the upper electrode 111, and is made of the material of the upper electrode 111, such as Ir or Pt. The piezoelectric layer 512 is a portion that becomes the piezoelectric member 112.

[0039] Next, the insulating pattern 13 is formed on the piezoelectric layer 512 (FIG. 3B). As described above, the insulating pattern 13 is arranged so as to match the position that contains the piezoelectric member 112 that will be formed later by pattern etching the piezoelectric layer 512. The insulating pattern 13 may be obtained by a well-known technique, for example, forming a silicon oxide layer on the piezoelectric layer 512, applying a resist layer, exposing and developing the resist layer to match the opening pattern, and then pattern etching the silicon oxide in the opening portion. Alternatively, the insulating pattern 13 may be obtained by exposing and developing a photosensitive permanent resist to match the opening pattern, and hardening the resist. The edge of the opening may be an inclined surface. This makes it easier to continuously form the lower electrode layer 141, the insulating layer 142, and the Ni seed layer 143 that will be formed later.

[0040] Along the insulating pattern 13 and the surface of the piezoelectric layer 512 in the openings, a lower electrode layer 141 (second conductive film), an insulating layer 142, and a Ni seed layer 143 are formed in this order (FIG. 3C). These three layers constituting the diaphragm 14 (collectively, the diaphragm layer including the second conductive film) may have a continuous layer structure across the positions of the openings of the insulating patterns 13. FIGS. 3A to 3C constitute a first formation step of the manufacturing method of this embodiment.

[0041] A photoresist film 631 is formed on the Ni seed layer 143 of the diaphragm 14. A negative dry film resist having a predetermined thickness is used for the photoresist film 631, and a plurality of sheets may be laminated to obtain a desired thickness according to the height of the first region 1551. A mask pattern 731 is also defined in accordance with the first region 1551 of the pressure chamber 155 (FIG. 4A). The photoresist film 631 is exposed and developed, and the exposed portion is generated as a first plating resist pattern 31 that corresponds to (defines) the first region 1551 (FIG. 4B).

[0042] A first layer 151 of the partition portion 15 is formed in the portion where the first plating resist pattern 31 does not remain (around the first plating resist pattern 31) (FIG. 4C). The first layer 151 is a metal film formed by, for example, electroplating so that the first layer 151 has the same thickness as the first plating resist pattern 31. Thereafter, the first plating resist pattern 31 is removed (FIG. 4D).

[0043] Thereafter, a photoresist film 632 is formed to fill the portion from which the first plating resist pattern 31 has been removed, and a thickness of which is appropriately determined on the first layer 151, thereby determining a mask pattern 732 that matches the portion corresponding to the second region 1552 of the pressure chamber 155 (FIG. 5A). The opening range of the mask pattern 732 includes (including at least a part of when viewed from above) the opening range of the mask pattern 731. For example, the opening range of the mask pattern 732 is a circle with a large radius and a center position equal to that of the opening range of the mask pattern 731. The photoresist film 632 is exposed and developed, and the exposed portion is generated as a second plating resist pattern 32 that corresponds to (defines) the first region 1551 and the second region 1552 (FIG. 5B).

[0044] A second layer 152 of the partition portion 15 is formed in the portion where the second plating resist pattern 32 does not remain (around the second plating resist pattern 32) (FIG. 5C). The second layer 152 is a thick metal film formed by, for example, electroplating so that the second layer 152 has the same thickness as the second plating resist pattern 32. Here, the second layer 152 is thicker than the first layer 151. Thereafter, the second plating resist pattern 32 is removed (FIG. 5D). The processes in FIGS. 4A to 5D constitute the second formation step of the manufacturing method of this embodiment, and the partition portion 15 is formed.

[0045] The substrate 50 is removed from the above structure (FIG. 6A). From FIG. 6A onwards, the structure is upside down compared to FIG. 5D. The exposed conductive layer 511 is pattern-etched to form the upper electrodes 111 (FIG. 6B). The pattern etching may be performed so that the range of the upper electrodes 111 is included within the first layer portion of the pressure chamber 155. Next, the piezoelectric layer 512 is pattern-etched to form the piezoelectric member 112. As a result, the piezoelectric element 11 is obtained (FIG. 6C). FIGS. 6B and 6C constitute a third formation step of the manufacturing method of this embodiment.

[0046] A protective film 16 is formed so as to completely cover the upper electrode 111, the piezoelectric member 112, and the insulating pattern 13 (FIG. 7A). The nozzle plate 20 is bonded to the second layer 152 of the partition wall portion 15 (FIG. 7B). The nozzle plate 20 may be bonded using an adhesive material, such as a resin-based material. Thereafter, bonding of electrical wiring to the upper electrode 111 and the lower electrode layer 141 as appropriate, and bonding of ink chambers that supply ink to ink flow paths (not shown) may be performed according to conventionally known techniques.

[0047] In the above, first plating resist pattern 31 is removed in FIG. 4D, and then photoresist film 632 is formed, and second layer 152 is formed. However, photoresist film 632 may be formed without removing first plating resist pattern 31, and after second layer 152 is formed, first plating resist pattern 31 and second plating resist pattern 32 may be removed together.

[0048] Figures 8A to 9C are cross-sectional views showing Modification 1 of a part of a method for manufacturing an inkjet head. These Figures 8A to 9C are modifications of the part of Figures 4A to 5D of the above embodiment.

[0049] 8A and 8B are the same as FIGS. 4A and 4B, respectively. After exposing the area of ​​the photoresist film 631 (first resist film) corresponding to the first plating resist pattern 31 by the mask pattern 731, the photoresist film 632 (second resist film) is formed without developing and removing the unexposed portion of the photoresist film 631, and a mask pattern 732a is determined (FIG. 8C). In this case, the opening area of ​​the mask pattern 732a (i.e., the area of ​​the second plating resist pattern 32) is smaller than and included in the exposure area (opening area, i.e., the area of ​​the first plating resist pattern 31) by the mask pattern 731, contrary to the above embodiment. The area of ​​the second plating resist pattern 32a laminated with the first plating resist pattern 31 is exposed (FIG. 8D). The unexposed areas other than the areas of the first plating resist pattern 31 and the second plating resist pattern 32a are developed and removed together (FIG. 9A).

[0050] The first and second layer portions of the partition wall portion 15a are formed together in the portion of the diaphragm 14 (Ni seed layer 143) that is not covered by either the developed first plating resist pattern 31 or the developed second plating resist pattern 32a (FIG. 9B). The first and second plating resist patterns 31 and 32a are removed to obtain the pressure chamber 155a (FIG. 9C).

[0051] 10A to 11C are cross-sectional views showing Modification 2 of a part of a method for manufacturing an inkjet head. Similar to Modification 1, Fig. 10A to Fig. 11C are modifications of the portion of Fig. 4A to Fig. 5D of the above embodiment, and are for the case where a positive photoresist (such as a dry film resist) is used.

[0052] A positive photoresist film 631b (first resist film) is formed, and then a mask pattern 731b is defined so as to cover the position of first plating resist pattern 31 (FIG. 10A). Exposure is performed leaving the portion covered by mask pattern 731b (the range of first plating resist pattern 31), so that the range other than first plating resist pattern 31 can be removed by development (FIG. 10B).

[0053] A photoresist film 632b (second resist film) is further formed on the exposed photoresist film 631b, and a mask pattern 732b is defined so as to cover the position of the second plating resist pattern 32b (FIG. 10C). In this case, the area covered by the mask pattern 732b is wider than the area covered by the mask pattern 731b and includes it. The areas covered by the mask patterns 731b and 732b may be concentric in plan view. By performing exposure while leaving the portion covered by the mask pattern 732b (the area of ​​the second plating resist pattern 32b), the area other than the second plating resist pattern 32b can be removed by development (FIG. 10D).

[0054] The first plating resist pattern 31 and the second plating resist pattern 32b are developed together, and the photoresist films 631b, 632b in the exposed portions are removed (FIG. 11A). The first layer portion and the second layer portion of the partition wall portion 15b are formed together in the portion of the diaphragm 14 (Ni seed layer 143) that is not covered by either the first plating resist pattern 31 or the second plating resist pattern 32b (FIG. 11B). The first plating resist pattern 31 and the second plating resist pattern 32b are removed, and the pressure chamber 155b is formed (FIG. 11C).

[0055] In both of the above-described embodiment and modified examples, the first plating resist pattern 31 is formed thinner than before, improving the accuracy of the shape at the corners between the side walls of the pressure chambers 155, 155a, 155b of the partition portions 15, 15a, 15b and the diaphragm 14. The degree of improvement in accuracy depends on the thickness of the first plating resist pattern 31, but for example, for multiple pressure chambers 155, the deviation in width (circle diameter) of the first region 1551 at the position where the first layer 151 contacts the diaphragm 14 can be reduced to 1.0% or less with respect to the average value (reference width) of the widths (circle diameters) of the first regions 1551.

[0056] As described above, the inkjet head 100 of this embodiment comprises a nozzle plate 20 having a plurality of nozzle holes 21 for ejecting ink, a partition portion 15 separating a plurality of pressure chambers 155 each communicating with the plurality of nozzle holes 21, a vibration plate 14 forming one side of the plurality of pressure chambers 155, and piezoelectric elements 11 each in contact with the outside of the plurality of pressure chambers 155 of the vibration plate 14. The amount of deviation of the position where the side wall of the pressure chamber 155 of the partition portion 15 comes into contact with the vibration plate 14 from the designed reference position is 1.0% or less with respect to the reference width of the multiple pressure chambers 155. In this way, by reducing the variation in the position where the side wall of the partition portion 15 and the vibration plate 14 come into contact and more precisely fixing both ends (nodes) of the vibration of the vibration plate 14, the ink ejection characteristics can be more precisely stabilized in the inkjet head 100, and ink can be ejected at the desired ink volume and speed. Particularly in an inkjet head having many nozzles, the variation in the structure of all the nozzles is reduced, and the characteristics of each nozzle become closer to uniform, so that the occurrence of nozzles with large variations that have initial ejection problems is suppressed, and the effort of adjusting the drive for each nozzle can also be simplified.

[0057] Further, the nozzle plate 20 forms a surface of the pressure chamber 155 facing the vibration plate 14, and the pressure chamber 155 has a plurality of regions different from each other in size or shape (here, width), i.e., a first region 1551 and a second region 1552, which overlap in the height direction from the nozzle plate 20 side to the vibration plate 14 side. This allows the height of the first region 1551 including the portion where the pressure chamber 155 and the vibration plate 14 contact each other to be smaller than before, thereby improving the accuracy of photolithography and allowing the first region 1551 to be formed with higher accuracy.

[0058] In addition, the height of first region 1551 closest to diaphragm 14 is smallest among first region 1551 and second region 1552. That is, by making the height of first region 1551 in contact with diaphragm 14 smaller, the precision of photolithography can be further improved to form first region 1551 with an accurate shape, and the vibration of diaphragm 14 can be accurately determined.

[0059] Moreover, the partition wall 15 is made of metal. Generally, metal has high rigidity, so it functions appropriately as a vibration node of the diaphragm 14.

[0060] The metal includes at least nickel, which has high rigidity and is stable against ink, and can therefore be suitably used as the partition wall 15.

[0061] The partition 15 is an electroplated thick film. That is, since a metal such as Ni is stably and firmly bonded to the Ni seed layer 143, the strength of the structure can be stably maintained. Also, there is no need to worry about peeling of the adhesive, insufficient filling, or overflow, and the nodes of the diaphragm 14 can be determined with high precision.

[0062] In addition, the manufacturing method of the inkjet head 100 of this embodiment includes a first formation step of sequentially forming on a substrate 50 a conductive layer 511, a piezoelectric layer 512, an insulating pattern 13 having openings corresponding to the multiple pressure chambers 155, and a vibration plate 14 including a lower electrode layer 141; a second formation step of defining a first region 1551 inside the opening of the insulating pattern 13 using a first plating resist pattern 31 in a plan view seen from a direction perpendicular to the substrate 50, and defining a second region 1552 using a second plating resist pattern 32 in an area including at least a portion of the defined first region 1551, thereby forming a partition portion 15 by plating to separate the multiple pressure chambers 155 including each of the first region 1551 and the second region 1552; and a third formation step of removing the substrate 50 and then pattern-etching the conductive layer 511 and the piezoelectric layer 512 to form piezoelectric elements 11 corresponding to the multiple pressure chambers 155. In this way, partition portion 15 is formed by stacking two layers on diaphragm 14 by plating, which improves the photolithographic precision of each layer, particularly first layer 151, and also enables the formation of partition portion 15, particularly the joint portion with diaphragm 14, with a stable and precise shape according to the precise photolithography.

[0063] In the second formation step, the first layer 151 of the partition portion 15 is formed around the defined first region 1551, and then the second layer 152 of the partition portion 15 is formed around the defined second region 1552. In this way, by repeating the formation of a similar partition twice, it is possible to easily and simply obtain a partition portion 15 with higher accuracy. This allows the vibration plate 14 to vibrate with smaller variation, thereby enabling stable ink ejection.

[0064] Furthermore, in the manufacturing method of Modification 1, in the second formation step, a negative photoresist film 632 is formed on the negative photoresist film 631 to which the range of first plating resist pattern 31 has been exposed, and the range contained in the range of first plating resist pattern 31 in plan view is exposed as the range of second plating resist pattern 32a, and partition wall portion 15 is formed in the portion not covered by either the developed first plating resist pattern 31 or second plating resist pattern 32a. In this way, even if the development processes are carried out in one go, partition wall portion 15 with good accuracy similar to that described above can be obtained.

[0065] Furthermore, in the manufacturing method of variant example 2, in the second formation step, a positive photoresist film 632b is formed on the positive photoresist film 631b that has been exposed leaving the area of ​​first plating resist pattern 31, and the photoresist film 632b is exposed leaving the area that includes the area of ​​first plating resist pattern 31 in a planar view as the area of ​​second plating resist pattern 32b, and partition portion 15b is formed in the portion that is not covered by either the developed first plating resist pattern 31 or second plating resist pattern 32b. In this way, even when a positive photoresist is used, the development processes can be carried out all at once as in the first modification, reducing the amount of work required, and a highly accurate partition wall portion 15b can be obtained.

[0066] The first plating resist pattern 31 and the second plating resist pattern 32 are formed of a dry film resist. By forming the resist pattern using a thin film resist in this manner, it is possible to form a resist pattern with good positional accuracy and to form the partition wall portion 15 accordingly, thereby reducing the variation in the vibration characteristics of the diaphragm 14 and enabling stable ink ejection.

[0067] The present invention is not limited to the above-described embodiment, but may be modified in various ways. For example, in the above embodiment, the first region 1551 is described as being thinner than the second region 1552, but the present invention is not limited to this.

[0068] In the above embodiment, the pressure chamber 155 is described as being divided into the first region 1551 and the second region 1552 having different widths, but this is not limited to this. The pressure chamber 155 may be divided into three or more regions having different widths as long as the shape does not adversely affect the ejection of ink.

[0069] Furthermore, if the pressure chamber 155 has a structure in which the height thereof is sufficiently small, it is not necessary to divide it into regions of two or more widths.

[0070] In the above embodiment, the central positions of the regions are set to be the same in plan view, but this is not limited to the above. The central positions may be shifted, and the positional relationship may not be such that the narrower region is contained within the wider region in plan view. Alternatively, two regions of the same size may be stacked.

[0071] In the above embodiment, each region of the pressure chamber 155 is described as being cylindrical or a shape combining a semi-cylinder and a rectangular column, but may be other shapes, such as a rectangular column shape, a shape with at least a part of the corners of the rectangular column shape rounded, or an ellipse. Alternatively, the partition wall 15 of the pressure chamber 155 may be an inclined truncated cone shape. In the case of a truncated cone shape, the reference width of the part in contact with the vibration plate 14 may be a design width determined by the part in contact with the vibration plate 14 according to the inclination of the partition wall 15. In the case of a shape that is not point-symmetric, such as a rectangular column or an ellipse, the reference width may be different depending on the direction, or the reference width may be fixed to the average value of the design width in each direction. In addition, in practical use, the average position of the side wall of the first layer 1551 may be set as a reference position, and the amount of protrusion of the skirt and the amount of depression of the bottom narrowing relative to this reference position may be evaluated as the amount of deviation.

[0072] In the above embodiment, the partition portion 15 is formed on the Ni seed layer 143 by electroplating, but this is not limiting. The partition portion 15 may be formed by other plating methods such as electroless plating. In addition, the specific configurations, contents and procedures of the processing operations, etc. shown in the above embodiments can be modified as appropriate without departing from the spirit of the present invention. The scope of the present invention includes the scope of the invention described in the claims and its equivalents. [Industrial Applicability]

[0073] The present invention can be utilized in an ink-jet head and a method for manufacturing an ink-jet head. [Explanation of symbols]

[0074] 11 Piezoelectric element 111 Upper electrode 112 Piezoelectric components 13 Insulation Pattern 14 Diaphragm 141 Lower electrode layer 142 Insulating layer 143 Ni seed layer 15, 15a, 15b bulkhead 151 1st layer 152 2nd layer 155, 155a, 155b Pressure chamber 1501 Hem pull 1502 Bottom Constriction 1551 First area 1552 Second area 16 Protective film 20 Nozzle plate 21 Nozzle hole 31, 32, 32a, 32b Resist patterns 50 Substrates 100 Inkjet head 511 Conductive layer 512 Piezoelectric layer 631, 631b, 632, 632b Photoresist film 731, 731b, 732, 732a, 732b mask patterns

Claims

1. a nozzle plate having a plurality of nozzle holes for ejecting ink; a partition wall portion separating a plurality of ink chambers each of which communicates with the plurality of nozzle holes; a vibration plate forming one surface of the ink chambers; a piezoelectric element in contact with an outer side of each of the ink chambers of the vibration plate; Equipped with a deviation amount of a position where a wall surface of the ink chamber of the partition portion contacts the vibration plate from a predetermined reference position is 1.0% or less with respect to a reference width of the plurality of ink chambers, the nozzle plate defines a surface of the ink chamber facing the vibration plate, the partition wall is made of metal, the ink chamber has a plurality of regions in a height direction from the nozzle plate side to the vibration plate side, the regions having a uniform shape in a cross section perpendicular to the height direction and different sizes or shapes in the cross section, The height of the region closest to the diaphragm is the smallest among the plurality of regions. Inkjet head.

2. 2. The ink jet head according to claim 1, wherein the metal includes at least nickel.

3. 3. The ink jet head according to claim 1, wherein the partition wall is an electroplated thick film.

4. a first forming step of sequentially forming, on a substrate, a first conductive film, a piezoelectric film, an insulating pattern having openings corresponding to the plurality of ink chambers, and a diaphragm layer including a second conductive film; a second forming step of defining a first region inside the opening portion by a first plating resist pattern in a plan view seen from a direction perpendicular to the substrate, and defining a second region by a second plating resist pattern in a range including at least a portion of the defined first region, thereby forming a partition wall portion that separates the plurality of ink chambers including each of the first region and the second region by plating; a third forming step of forming piezoelectric elements corresponding to the plurality of ink chambers by pattern-etching the first conductive film and the piezoelectric film after removing the substrate; A method for manufacturing an inkjet head, comprising:

5. In the second forming step, a first layer of the partition wall is formed around the defined first region.

5. The method of claim 4, further comprising the steps of: forming a second layer of the partition wall around the defined second region after forming the first layer.

6. 5. The method for manufacturing an inkjet head according to claim 4, wherein in the second formation step, a negative type second resist film is formed on a negative type first resist film to which an area of ​​the first plating resist pattern has been exposed, an area included in the area of ​​the first plating resist pattern in a planar view is exposed as the area of ​​the second plating resist pattern, and the partition portion is formed in a portion not covered by either the developed first plating resist pattern or the developed second plating resist pattern.

7. 5. The method for manufacturing an inkjet head according to claim 4, wherein in the second formation step, a positive type second resist film is formed on a positive type first resist film that has been exposed while leaving an area of ​​the first plating resist pattern, and the second resist film is exposed while leaving an area that includes the area of ​​the first plating resist pattern in a planar view as the area of ​​the second plating resist pattern, and the partition portion is formed in a portion that is not covered by either the developed first plating resist pattern or the developed second plating resist pattern.

8. The method for manufacturing an inkjet head according to any one of claims 4 to 7, wherein the first plating resist pattern and the second plating resist pattern are formed from a dry film resist.

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