Flow path member and liquid ejection head

Abstract

To provide a passage member which can inhibit a passage formed at a substrate from being clogged by an adhesive, and to provide a liquid discharge head using the passage member.SOLUTION: A passage member 116 has: a first substrate 21 in which a passage 11 is formed from a first surface 111; and a second substrate 22 having a second surface 112. An adhesive 13 is placed in a space between the first surface 111 and the second surface 112 to join the first substrate 21 and the second substrate 22 to each other. When the passage 11 is viewed from a direction orthogonal to the first surface 111, the passage 11 has a polygonal shape including corner parts. The passage 11 has: a first portion 113 located at the first surface side; and a second portion 114 communicating with the first portion 113. An opening area of the second portion 114 is larger than an opening area of the first portion 113, and the adhesive exists at a step surface 33 between the first portion 113 and the second portion 114 and the corner parts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flow path member and a liquid ejection head using the same. [Background technology]

[0002] Patent Document 1 discloses a liquid ejection device that performs recording by ejecting liquid. The liquid ejection device has a liquid ejection head that includes an ejection port that ejects liquid, a flow path for supplying liquid to the ejection port, a piezoelectric element that generates pressure for ejecting the liquid, and a pressure chamber on which the pressure of the piezoelectric element acts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-91272 Summary of the Invention [Problem to be solved by the invention]

[0004] A liquid ejection head such as that disclosed in Patent Document 1 is generally formed by bonding, with an adhesive, a plurality of substrates each having a flow path through which liquid flows.

[0005] However, when bonding multiple substrates with an adhesive, excess adhesive may flow into the flow paths and clog the flow paths, which may cause problems such as an inability to supply liquid to the ejection ports.

[0006] In view of the above-mentioned problems, an object of the present invention is to provide a flow path member that can prevent flow paths formed in a substrate from being blocked by an adhesive, and a liquid ejection head using the same. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a flow path member comprising: a first substrate having a flow path formed from a first surface; and a second substrate having a second surface opposite to the first surface; wherein an adhesive is present between the first surface and the second surface, and the first substrate and the second substrate are joined together; when the flow path is viewed from a direction perpendicular to the first surface, the flow path has a polygonal shape with corners; the flow path has a first portion located on the first surface side and a second portion communicating with the first portion; when the flow path is viewed from a direction perpendicular to the first surface, an opening area of ​​the second portion is larger than an opening area of ​​the first portion; and the adhesive is present at a step surface between the first portion and the second portion and at the corners. and an upper end of the second portion is open in a direction in which the first portion and the second portion communicate with each other. It is characterized by: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a flow path member that can prevent a flow path formed in a substrate from being blocked by an adhesive, and a liquid ejection head using the same. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. [Figure 2] FIG. 3 is a cross-sectional view showing each substrate before bonding. [Figure 3] FIG. 1 is a diagram showing a first embodiment. [Figure 4A] 5A to 5C are diagrams illustrating a manufacturing process of a liquid ejection head. [Figure 4B] 5A to 5C are diagrams illustrating a manufacturing process of a liquid ejection head. [Figure 5] FIG. [Figure 6] FIG. 10 is a diagram showing a third embodiment. [Figure 7] 10A to 10C are diagrams showing manufacturing steps of the third embodiment. [Figure 8] FIG. 10 is a diagram showing a fourth embodiment. [Figure 9] FIG. 10 is a diagram showing a fifth embodiment. [Figure 10]FIG. 10 is a diagram showing a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that, although specific descriptions may be used in the embodiments described below to fully explain the present invention, these are merely examples that are technically preferred and do not particularly limit the scope of the present invention.

[0011] (First embodiment) FIG. 1 is a cross-sectional view of a liquid ejection head 110. FIG. 2(a) is a cross-sectional view of a protection substrate 21 before the substrates shown in FIG. 1 are bonded together. FIG. 2(b) is a cross-sectional view of an actuator substrate 22 before the substrates shown in FIG. 1 are bonded together. FIG. 2(c) is a cross-sectional view of a nozzle substrate (ejection port substrate) 23 before the substrates shown in FIG. 1 are bonded together. As shown in FIG. 1, the liquid ejection head 110 is composed of at least a protection substrate (first substrate) 21, an actuator substrate 22 (second substrate), and a nozzle substrate 23 (third substrate). The flow path member 116 includes a protection substrate (first substrate) 21 and an actuator substrate 22 (second substrate).

[0012] The actuator substrate 22 is made of, for example, a silicon substrate, and defines a plurality of cavities (pressure chambers) 12. The actuator substrate 22 supports a vibration membrane 14 on its surface. The vibration membrane 14 forms the ceiling wall of the cavity 12, and defines the cavity 12. A piezoelectric element (pressure generating element) 15 is disposed on the vibration membrane 14, which generates pressure for ejecting liquid from the ejection port.

[0013] A nozzle substrate 23 is bonded to the back surface of the actuator substrate 22. The nozzle substrate 23 is made of, for example, a silicon substrate, and is bonded to the back surface of the actuator substrate 22. Together with the actuator substrate 22 and the vibration membrane 14, it defines a cavity. The nozzle substrate 23 has a liquid ejection flow path 16 that overlaps with the cavity portion, and an ejection port 17 is formed in the bottom surface of the liquid ejection flow path. The ejection port 17 penetrates the nozzle substrate 23 and is located on the opposite side to the cavity 12. Therefore, when a change in the volume of the cavity 12 occurs, the liquid stored in the cavity 12 passes through the liquid ejection flow path 16 and is ejected from the ejection port 17.

[0014] The protective substrate 21 is made of, for example, a silicon substrate. The protective substrate 21 is arranged so as to cover the piezoelectric elements 15, and is bonded to the surface of the actuator substrate 22 via an adhesive 13. The adhesive 13 is located between the first surface 111 and the second surface 112, thereby bonding the protective substrate 21 and the actuator substrate 22. The protective substrate 21 has a recess 18 on the surface facing the surface of the actuator substrate 22. A plurality of piezoelectric elements 15 corresponding to the plurality of cavities 12 are housed in the recess 18. The recess 18 surrounds the piezoelectric elements 15 to protect them from liquids and the like.

[0015] The flow path 11 formed in the protection substrate (first substrate) 21 has a first portion 113 and a second portion 114. The first portion 113 is a portion connected to an opening 115 on the actuator substrate 22 side of the flow path 11. The second portion 114 is a portion connected to the first portion 113.

[0016] An ink tank (not shown) is disposed on the protective substrate 21. A flow path 11 is formed so as to penetrate the protective substrate 21. The flow path 11 in the protective substrate 21 communicates with a cavity 12 in the actuator substrate. Therefore, the liquid in the ink tank passes through the flow path 11 and is supplied to the cavity 12.

[0017] A piezoelectric actuator is formed by disposing a piezoelectric element 15 on the vibration membrane 14. The piezoelectric element 15 includes a lower electrode (not shown) formed on the vibration membrane forming layer, the piezoelectric element 15 formed on the lower electrode, and an upper electrode (not shown) formed on the piezoelectric element.

[0018] For example, a PZT (lead zirconate titanate) film formed by a sol-gel method or a sputtering method can be used as the piezoelectric element 15. Such a piezoelectric element 15 is made of a sintered body of metal oxide crystal.

[0019] Piezoelectric element 15 is formed at a position facing cavity 12 across vibrating membrane 14. In other words, piezoelectric element 15 is formed so as to contact the surface of vibrating membrane 14 on the side opposite cavity 12. Vibrating membrane 14 has the property of being deformable in the direction facing cavity 12.

[0020] When a drive voltage is applied to the piezoelectric element 15 from a drive IC (not shown), the piezoelectric element 15 is deformed due to the inverse piezoelectric effect. This causes the vibration membrane 14 to deform together with the piezoelectric element 15, which in turn causes a change in the volume of the cavity 12 and pressurizes the liquid within the cavity 12. The pressurized liquid passes through the liquid discharge flow path 16 and is discharged from the discharge port 17 as minute droplets.

[0021] FIG. 3 shows a cross-sectional view and a plan view of the protective substrate 21 and the actuator substrate 22 after bonding them with the adhesive 13. As shown in FIG. 3, a recess 18 and a flow path 11 are formed in the protective substrate 21. The protective substrate 21 is configured as an integrated substrate. The connection between the first portion 113 and the second portion 114 of the flow path 11 is a stepped portion, forming a stepped surface 33. When the flow path 11 is viewed from a direction perpendicular to the first surface 111 (in a plan view), the flow path has a polygonal shape with corners. In FIG. 3, it is a rectangle. The opening area of ​​the second portion 114 (large opening 31) is larger than the opening area of ​​the first portion 113 (small opening 32). Therefore, the flow path 11 formed in the protective substrate 21 has a stepped surface 33 midway through the thickness of the protective substrate, where the large opening 31 and the small opening 32 communicate with each other. As a result, the flow channel 11 is formed so that the cross-sectional area increases from the first surface 111 toward the rear surface in a cross-sectional view.

[0022] When the flow path 11 has corners, the adhesive 19 tends to creep up from the corners due to capillary action, making it easier to control the position where the adhesive creeps up. If there are no corners, for example, in a shape close to a circle, the adhesive creeps up all around, which may block the opening of the flow path 11 when viewed in a plan view. In contrast, if the flow path 11 has corners, the adhesive flows preferentially around the corners rather than all around the flow path, and then flows into the step surface 33 formed in the step portion, thereby preventing the flow path from being blocked. Because a certain amount of adhesive can be retained on the step surface 33, further creeping up of the adhesive beyond the step surface can be prevented, preventing the flow path from being blocked. Therefore, excess adhesive remains at the corners and the step surface, preventing it from blocking the flow path.

[0023] In this embodiment, the thickness of the protective substrate 21 is 100 μm to 600 μm. In addition, when viewed in the cross-sectional view of Fig. 3, the left-right length of the small opening of the flow channel 11 is 50 μm to 100 μm, and the left-right length of the large opening is 80 μm to 150 μm. However, the relationship that the opening area of ​​the large opening is greater than the opening area of ​​the small opening is maintained and is not reversed.

[0024] Next, a method for manufacturing a liquid ejection head according to this embodiment will be described with reference to Figures 4A(a) to 4B(j). Figure 4 is a schematic diagram of each manufacturing process. The method for manufacturing a liquid ejection head is broadly divided into a process for forming a protection substrate 21, a process for forming an actuator substrate 22, a process for forming a nozzle substrate 23, and a process for bonding these together. This embodiment aims to prevent the adhesive from creeping up when bonding the protection substrate 21 and the actuator substrate 22, but it can also be applied to other bonding processes.

[0025] 4A(a), a protection substrate (silicon substrate) having a thickness of 400 μm was prepared, and an etching mask 41 having an opening in the region where the flow channel 11 was to be formed was formed on the surface opposite to the surface to be bonded to the actuator substrate 22. The etching mask was formed by exposing and developing a novolac-based photoresist.

[0026] 4A(b), this mask was used to dry-etch Si to form a large opening 31 of the flow channel 11 partway through the thickness of the protective substrate 21. The etching depth was set to 300 μm, and an etching technique known as the Bosch process was used, which uses SF gas for the etching step and CF gas for the coating step. However, it is also possible to form the opening using methods other than the Bosch process.

[0027] Next, the etching mask 41 was removed, and as shown in Fig. 4A(c), an etching mask 42 was provided on the surface of the protection substrate 4 that was to be bonded to the actuator substrate. The etching mask 42 was formed by first using a novolac-based positive resist, and then by exposing and developing it.

[0028] Next, as shown in Fig. 4A(c), using the etching mask 42 as a mask, the protective substrate 21 was etched by Si dry etching to form small openings 32, which were connected to the large openings to form the flow paths 11. The etching conditions used in this case were a technique known as the Bosch process, which uses an etching step and a coating step. At the same time as forming the small opening 32, a recess 18 was also formed to accommodate the vibration membrane and piezoelectric element portion that would later be formed on the surface of the actuator substrate. The depth was increased from 100 μm to 120 μm.

[0029] Thereafter, the resist mask 42 was removed, and the protective substrate 21 was formed as shown in FIG. 4A(d).

[0030] On the other hand, the preparation process for the actuator substrate 22 is as follows. First, as shown in Fig. 4A(e), a 600 μm thick actuator substrate (silicon substrate) is prepared, and a vibration film formation layer is formed on the surface of the actuator substrate. The vibration film formation layer is formed by, for example, plasma CVD.

[0031] Next, a hydrogen barrier film (not shown), a lower electrode (not shown), a piezoelectric film, and an upper electrode (not shown) are formed in this order on the vibration film formation layer. The lower electrode and upper electrode are formed by, for example, a sputtering method, and the piezoelectric film is formed by a sol-gel method, but may also be formed by a sputtering method. In this way, the piezoelectric element 15 is formed. An actuator substrate is formed by forming an interlayer film and a wiring layer so that the actuator section can be driven.

[0032] Next, the multiple films on the actuator substrate were etched to form liquid supply paths 44 that penetrated the piezoelectric films and electrodes.

[0033] Next, as shown in FIG. 4A(f), an adhesive was applied to the opposing surface of the protective substrate 21 to a thickness of 1.0 μm to 2.0 μm, and the actuator substrate 22 and the protective substrate 21 were bonded together so that the flow path 11 and the liquid supply path 44 were aligned. The adhesive was applied by spin-coating the adhesive onto a dry film and then transferring it to the protective substrate 21. However, the adhesive application method is not limited to this, and screen printing or photolithography patterning using a photosensitive adhesive may also be used.

[0034] The adhesive is preferably thick to eliminate voids during bonding, and is set to a thickness of 1.0 μm or more, preferably 2.0 μm, and more preferably 5.0 μm or more. By increasing the thickness of the adhesive, the amount of adhesive creeping up into the through-holes of the protective substrate increases when bonded, but it is possible to capture the adhesive creeping up at the step where the small opening changes to the large opening. Furthermore, by providing corners in the shape of the through-hole, it is possible to control the position of the adhesive creeping up, making it easier to capture it.

[0035] As a result, the adhesive creeping up from the corners flows into the step surface formed in the step portion, and thus blocking of the flow path can be suppressed.

[0036] 4B(g), the actuator substrate was thinned by grinding from the rear surface, after which a resist mask was formed on the rear surface, and a cavity 12 was formed by dry etching.

[0037] Next, as shown in Fig. 4B(i), a nozzle substrate 23 was prepared. After forming a liquid ejection flow path 16 in the nozzle substrate 23, the actuator substrate and the nozzle substrate were bonded together, and then an ejection port 17 was formed. Thereafter, as shown in Fig. 4B(j), the nozzle substrate 23 was bonded to the back surface of the actuator substrate 22 so as to cover the cavity 12 of the actuator substrate 22.

[0038] Through the above steps, the liquid ejection head 110 of this embodiment was manufactured.

[0039] (Second embodiment) A second embodiment will be described. Note that similar parts to those in the first embodiment are designated by similar reference numerals, and their description will be omitted. Differences from the first embodiment will be mainly described. FIG. 5 shows a cross-sectional view and a plan view of a protective substrate 21 in this embodiment. In this embodiment, as shown in FIG. 5, the large opening 31 of the flow path 11 in the protective substrate has a circular shape in plan view. This allows the adhesive to creep up from the corners of the small openings 32, retaining excess adhesive on the stepped surface 33 of the large opening, and preventing the adhesive from creeping up further from the stepped surface 33. When the large opening 31 has a circular shape in plan view, the large opening 31 does not have corners where the adhesive is likely to creep up, and therefore further creeping up of the adhesive can be prevented.

[0040] (Third embodiment) A third embodiment will be described. Note that similar parts to those in the first embodiment are assigned similar reference numerals, and their description will be omitted. The following description will focus on differences from the first embodiment. FIG. 6 is a cross-sectional view and a plan view of the protective substrate 21 in this embodiment. In this embodiment, a protrusion 51 that protrudes toward the large opening 31 (second portion) is provided on the stepped surface formed on the protective substrate 21. With this embodiment, the adhesive creeps up from the corner and reaches the pointed portion 51, making it easier for the adhesive that exceeds the pointed portion 51 to be captured by the stepped surface. Although it is possible that the adhesive may move due to the influence of heat or the like after bonding, the adhesive captured between the pointed portion 51 and the stepped surface does not move any further, thereby further suppressing blockage of the flow path.

[0041] 7(a) to 7(c) show a manufacturing method of the pointed portion 51. The order of processing the small openings 32 and the large openings 31 of the flow path 11 in the protective substrate 21 is reversed, that is, the small openings are formed first, and then the large openings are formed and connected to form the pointed portion 51. As shown in FIG. 7, after processing the small openings 32 to a depth of about 100 μm, the large openings 31 are processed from the opposite surface to connect them, making it possible to form the pointed portion 51 as shown in FIG. 7(c).

[0042] (Fourth embodiment) A fourth embodiment will be described. Note that similar parts to those in the first embodiment are designated by similar reference numerals, and their description will be omitted. Differences from the first embodiment will be mainly described. Figure 8 shows a cross-sectional view and a plan view of a protective substrate 21 in this embodiment. As shown in Figure 8, this embodiment is characterized in that a plurality of small openings 32 are formed in the protective substrate 21, and one large opening 31 communicates with a plurality of small openings 32. By forming the large opening 31 so that it communicates with a plurality of small openings, the step surface 33 becomes a wide area after the adhesive creeps up from the small openings. This further suppresses blockage of the flow path. The large opening and the small opening were each formed by reactive ion etching of silicon.

[0043] (Fifth embodiment) A fifth embodiment will be described. Note that similar parts to those in the first embodiment are designated by similar reference numerals and will not be described again. Differences from the first embodiment will be mainly described. Figure 9 shows a cross-sectional view and a plan view of a protective substrate 21 in this embodiment. In this embodiment, the large openings of the flow channels in the protective substrate were formed by anisotropic wet etching of silicon. While TMAH was used as the etching solution, an alkaline solution such as KOH may also be used. Figure 9(a) shows the case where a silicon substrate (100) was used. Figure 9(b) shows the case where a silicon substrate (110) was used. Although the shapes are different in Figures 9(a) and 9(b), in both cases, a large opening was first formed, and then small openings were formed on the opposite side to connect multiple openings. The small openings were formed using reactive ion etching of Si.

[0044] When a (100) substrate is used, the area in the planar direction increases, resulting in a larger device chip. However, the cost of the substrate is low. Furthermore, the opening area of ​​the large opening increases toward the back surface of the first surface 111, reducing flow resistance and facilitating ink supply. Conversely, when a (110) substrate is used, the cost of the substrate is high. However, the cross-sectional surface can be formed vertically as shown in Figure 9(b), resulting in a smaller device chip. By forming the large opening using anisotropic wet etching as in Example 4, the step surface after the adhesive creeps up from the corner of the small opening is wide, resulting in a configuration that is less likely to become clogged.

[0045] (Sixth embodiment) A sixth embodiment will now be described. Note that the same parts as those in the first embodiment are given the same reference numerals, and a description thereof will be omitted. The following description will focus on the differences from the first embodiment. FIG. 10 is a cross-sectional view and a plan view of the protective substrate 21 in this embodiment. In this embodiment, as shown in FIG. 10, a plurality of step surfaces 33 are formed in the flow path (two in FIG. 10). By forming a plurality of step surfaces 33, there are a plurality of locations where the adhesive that creeps up can be captured. This makes it possible to further prevent the adhesive from clogging the flow path. [Explanation of symbols]

[0046] 11 Flow path 13 Adhesive 21 First substrate 111 First Side 112 Second Side 113 First Part 114 Second Part 116 Flow path components

Claims

1. a first substrate having a flow path formed on a first surface thereof; a second substrate having a second surface opposite to the first surface; and In a flow path member formed by bonding the first substrate and the second substrate together by providing an adhesive between the first surface and the second surface, When the flow path is viewed from a direction perpendicular to the first surface, the flow path has a polygonal shape having corners, the flow path has a first portion located on the first surface side and a second portion communicating with the first portion, When the flow path is viewed from a direction perpendicular to the first surface, an opening area of ​​the second portion is larger than an opening area of ​​the first portion, the adhesive is present on a step surface between the first portion and the second portion and on the corner portion, A flow path member, characterized in that an upper end of the second portion is open in a direction in which the first portion and the second portion communicate with each other.

2. The flow path member according to claim 1 , wherein the second portion has a circular shape when the flow path is viewed from a direction perpendicular to the first surface.

3. The flow path member according to claim 1 or 2, wherein the step surface is formed with a protruding portion that protrudes toward the second portion.

4. a plurality of the first portions are formed on the first substrate, The flow path member according to claim 1 , wherein the plurality of first portions communicate with one of the second portions.

5. The flow path member according to claim 1 , wherein the opening area of ​​the second portion increases toward the back surface of the first surface.

6. The flow path member according to claim 1 , wherein a plurality of the step surfaces are formed.

7. The second substrate further has a pressure generating element that generates pressure for discharging liquid, 7. The flow path member according to claim 1, wherein the first substrate further has a recess surrounding the pressure generating element.

8. a discharge port substrate having a discharge port for discharging a liquid; A flow path member according to any one of claims 1 to 6; In a liquid ejection head having the flow path formed in the first substrate of the flow path member is a flow path for supplying liquid to the ejection port, the second substrate further includes a pressure generating element that generates pressure for ejecting liquid; The liquid ejection head is characterized in that the first substrate further has a recess surrounding the pressure generating element.

9. The liquid ejection head according to claim 8 , wherein the ejection port substrate is bonded to the second substrate via an adhesive.

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