Flow path member and liquid ejecting head

Abstract

The present application relates to a flow channel member and a liquid ejection head. A flow channel member includes: a first substrate in which a flow channel is formed from a first surface; and a second substrate having a second surface facing the first surface; wherein the first substrate and the second substrate are adhered to each other by an adhesive between the first surface and the second surface; wherein the flow channel is polygonal when viewed from a direction orthogonal to the first surface; wherein the flow channel includes a first portion on the first surface side and a second portion communicating with the first portion; wherein an opening area of the second portion is larger than an opening area of the first portion when viewed from the direction orthogonal to the first surface; and wherein the adhesive is present on a step surface between the first portion and the second portion and at a corner tip of the polygon.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a flow path member and a liquid ejection head. BACKGROUND

[0002] Japanese Patent Application Laid-Open No. 2013-91272 discloses a liquid ejection apparatus that ejects liquid to perform recording. The liquid ejection apparatus includes a liquid ejection head that includes an ejection port that ejects liquid, a flow path that supplies liquid to the ejection port, a piezoelectric element that generates pressure for ejecting liquid, and a pressure chamber on which the pressure generated by the piezoelectric element acts.

[0003] The liquid ejection head disclosed in Japanese Patent Application Laid-Open No. 2013-91272 is generally formed by bonding a plurality of substrates in which flow paths are formed, with an adhesive, through which liquid flows.

[0004] However, when the plurality of substrates are bonded together with the adhesive, there is a possibility that excess adhesive flows into the flow paths and clogs the flow paths. When the flow paths are clogged, problems arise such as liquid failing to be supplied to the ejection port. SUMMARY

[0005] The present disclosure provides a flow path member that can prevent an adhesive from clogging flow paths formed in a substrate, and a liquid ejection head that uses the flow path member.

[0006] According to an aspect of the present disclosure, a flow path member includes: a first substrate in which a flow path is formed from a first surface; and a second substrate having a second surface facing the first surface; wherein the first substrate and the second substrate are bonded to each other by an adhesive between the first surface and the second surface; wherein the flow path is polygonal when viewed from a direction orthogonal to the first surface; wherein the flow path includes a first portion on the first surface side and a second portion communicating with the first portion; wherein an opening area of the second portion is larger than an opening area of the first portion when viewed from the direction orthogonal to the first surface; and wherein the adhesive is present on a step face between the first portion and the second portion and at a vertex of the polygon.

[0007] Other features of the present disclosure will become apparent from the following description of example embodiments with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is a cross-sectional view of a liquid ejection head.

[0009] Figures 2A-2C is a cross-sectional view of individual substrates before being bonded together.

[0010] Figure 3 is a diagram illustrating a first example embodiment.

[0011] Figures 4A-A to 4B-J This is a diagram showing the manufacturing process of a liquid injection head.

[0012] Figures 4B-G to 4B-J This is a diagram showing the manufacturing process of a liquid injection head.

[0013] Figure 5 This is a diagram illustrating a second exemplary embodiment.

[0014] Figure 6 This is a diagram illustrating a third exemplary embodiment.

[0015] Figures 7A to 7C This is a diagram illustrating a manufacturing process according to a third exemplary embodiment.

[0016] Figure 8 This is a diagram illustrating a fourth exemplary embodiment.

[0017] Figure 9A and Figure 9B These are figures illustrating the fifth exemplary embodiment.

[0018] Figure 10 This is a diagram illustrating a sixth exemplary embodiment. Detailed Implementation

[0019] Exemplary embodiments of the present disclosure will now be described with reference to the accompanying drawings. There may be instances where the following description of exemplary embodiments is given in detail to fully explain the present disclosure; however, such description is merely illustrative and not intended to specifically limit the scope of the present disclosure.

[0020] The first exemplary embodiment will now be described. Figure 1 This is a cross-sectional view of the liquid injection head 110. Figure 2A Is Figure 1 The cross-sectional view of the protective substrate 21 before the substrates are bonded together is shown. Figure 2B Is Figure 1 The diagram shows a cross-sectional view of the actuator substrate 22 before the substrates are bonded together. Figure 2C Is Figure 1 The cross-sectional view of the nozzle substrate (ejector substrate) 23 before the substrates are bonded together is shown. Figure 1 As shown, the liquid injection head 110 includes at least a protective substrate 21 (first substrate), an actuator substrate 22 (second substrate), and a nozzle substrate 23 (third substrate). The flow path component 116 includes the protective substrate 21 (first substrate) and the actuator substrate 22 (second substrate).

[0021] The actuator substrate 22 is formed of, for example, a silicon substrate and is divided into a plurality of cavities (pressure chambers) 12. A vibrating diaphragm 14 is supported on the surface of the actuator substrate 22.

[0022] The vibrating diaphragm 14 forms the top wall of the cavity 12 and divides the cavity 12.

[0023] A piezoelectric element (pressure generating element) 15 is arranged on the vibrating diaphragm 14, which generates pressure for ejecting liquid from the nozzle.

[0024] The nozzle substrate 23 is bonded to the back side of the actuator substrate 22. The nozzle substrate 23 is formed of, for example, a silicon substrate and is bonded to the back side of the actuator substrate 22. The nozzle substrate 23, together with the actuator substrate 22 and the diaphragm 14, defines the cavity 12. The nozzle substrate 23 includes a liquid jet flow path 16 arranged to overlap with the cavity portion, and a jet nozzle 17 is formed on the bottom surface of the liquid jet flow path 16. The jet nozzle 17 penetrates the nozzle substrate 23 and is located on the opposite side of the cavity 12. Therefore, when the internal volume of each cavity 12 changes, the liquid accumulated in the cavity 12 is ejected through the liquid jet flow path 16 and from the jet nozzle 17.

[0025] The protective substrate 21 is formed of, for example, a silicon substrate. The protective substrate 21 is arranged to cover the piezoelectric element 15 and is bonded to the surface of the actuator substrate 22 by an adhesive 13.

[0026] The protective substrate 21 and the actuator substrate 22 are bonded together using an adhesive 13 disposed between the first surface 111 and the second surface 112. The protective substrate 21 includes recesses 18 on its surface facing the actuator substrate 22. A plurality of piezoelectric elements 15 corresponding to each cavity 12 are accommodated within each recess 18. The recesses 18 serve to protect the piezoelectric elements 15 from liquid influence.

[0027] The flow path 11 formed in the protective substrate 21 (first substrate) includes a first portion 113 and a second portion 114. The first portion 113 is the portion connected to the orifice 115 of the flow path 11 on the actuator substrate 22 side. The second portion 114 is the portion connected to the first portion 113.

[0028] An ink reservoir (not shown) is disposed on a protective substrate 21. A flow path 11 is formed to penetrate the protective substrate 21. The flow path 11 of the protective substrate 21 communicates with a cavity 12 in the actuator substrate 22. Liquid in the ink reservoir flows through the flow path 11 and is supplied to the cavity 12.

[0029] A piezoelectric element 15 is disposed on a vibrating diaphragm 14 to form a piezoelectric actuator. The piezoelectric element 15 includes a lower electrode (not shown) formed on the vibrating diaphragm forming layer and an upper electrode (not shown) formed on the piezoelectric element 15.

[0030] For example, a piezoelectric zirconate titanate (PZT) film formed by sol-gel or sputtering methods can be used for piezoelectric element 15. This piezoelectric element 15 is made of a sintered body of metal oxide crystals.

[0031] A piezoelectric element 15 is formed at a position facing the cavity 12, separated from the diaphragm 14. That is, the piezoelectric element 15 is formed to contact the surface of the diaphragm 14 on the opposite side of the cavity 12. The diaphragm 14 has the property of being able to deform in the direction facing the cavity 12.

[0032] When a driving voltage is applied to the piezoelectric element 15 from a driving integrated circuit (IC) (not shown), the piezoelectric element 15 deforms due to the inverse piezoelectric effect. The diaphragm 14 thus deforms along with the piezoelectric element 15. This causes a change in the internal volume of the cavity 12 and applies pressure to the liquid within the cavity 12. The pressurized liquid flows through the liquid jet path 16 and is ejected as microdroplets from the jet nozzle 17.

[0033] Figure 3 A cross-sectional view and a top view are shown of the protective substrate 21 and the actuator substrate 22, which are bonded together using adhesive 13. Figure 3 As shown, the recess 18 and the flow path 11 are formed in the protective substrate 21. The protective substrate 21 is formed from a single substrate. A step (stepped portion) is formed at the connection between the first portion 113 and the second portion 114 of the flow path 11, thereby forming a stepped surface 33 between them. When the flow path 11 is viewed from a direction orthogonal to the first surface 111 (i.e., in a top view), the flow path 11 appears as a polygon with corners. Figure 3 In this configuration, the flow path 11 is quadrilateral. The orifice area of ​​the second portion 114 (large orifice portion 31) is larger than the orifice area of ​​the first portion 113 (small orifice portion 32). Therefore, the flow path 11 formed in the protective substrate 21 has a stepped surface 33 in the middle of the flow path 11 in the thickness direction of the protective substrate 21, and the large orifice portion 31 and the small orifice portion 32 are interconnected through the stepped surface. With this configuration, the flow path 11 is formed such that the cross-sectional area of ​​the flow path increases from the first surface 111 toward the back surface in a cross-sectional view.

[0034] By utilizing the corners in the flow path 11, the adhesive 19 will easily climb along the corners due to capillary action, and the position of the adhesive 19 climbing can be easily controlled. If the flow path 11 has, for example, an approximately circular shape without corners, the adhesive 19 will climb along the entire circumference. As a result, when viewed in a top view, the adhesive 19 may block the orifice of the flow path 11. Conversely, in a flow path 11 with corners, the adhesive 19 preferentially flows along the corners rather than along the entire circumference of the flow path 11, and flows towards the step surface 33 formed in the step portion. Therefore, it is possible to prevent the adhesive 19 from blocking the flow path 11. This configuration allows a certain amount of adhesive 19 to remain on the step surface 33, thereby preventing the adhesive 19 from climbing above the step surface 33 and blocking the flow path 11. Therefore, excess adhesive remains at the corners and on the step surface 33, thereby preventing it from blocking the flow path 11.

[0035] In this exemplary embodiment, the thickness of the protective substrate 21 is 100 μm to 600 μm. Figure 3 As shown in the cross-sectional view, the length of the small orifice 32 in the flow path 11 in the left-right direction is 50 μm to 100 μm, and the length of the large orifice 31 in the left-right direction is 80 μm to 150 μm. The relationship that the orifice area of ​​the large orifice 31 is greater than the orifice area of ​​the small orifice 32 is maintained and will not be reversed.

[0036] Next, refer to Figures 4A-A to 4B-J To describe the manufacturing method of the liquid injection head 110. Figures 4A-A to 4B-J This is a schematic diagram of each manufacturing process. The manufacturing method of the liquid injection head 110 mainly includes the process of forming a protective substrate 21, the process of forming an actuator substrate 22, the process of forming a nozzle substrate 23, and the process of bonding the substrates together. The manufacturing method according to this exemplary embodiment is intended to prevent adhesive creep when the protective substrate 21 and the actuator substrate 22 are bonded together, but it is also applicable to other bonding processes besides this bonding.

[0037] First, such as Figure 4A-A As shown, a protective substrate 21 (silicon substrate) with a thickness of 400 μm is prepared; an etching mask 41 is formed on the surface of the protective substrate 21 opposite to the surface to which the actuator substrate 22 is bonded, and the etching mask 41 has orifices in the area where the flow path 11 is to be formed. A phenolic resist is used for the etching mask 41. The etching mask 41 is formed by exposure and development.

[0038] like Figure 4A-BAs shown, a silicon (Si) dry etching is performed using this mask to form a large aperture 31 of the flow path 11 in the middle portion of the thickness direction of the protective substrate 21. The etching depth is set to 300 μm, and an etching method called the Bosch process is used, in which sulfur hexafluoride (SF6) gas is used in the etching step and octafluorocyclobutane (C4F8) gas is used in the coating step. However, the large aperture 31 can also be formed by methods other than the Bosch process.

[0039] Subsequently, the etched mask 41 is removed. (As follows) Figure 4A-C As shown, an etching mask 42 is formed on the surface of the protective substrate 21 that is bonded to the actuator substrate 22. A phenolic positive photoresist is used to form the etching mask 42. The etching mask 42 is formed by exposure and development.

[0040] Subsequently, using etching mask 42 as a mask, the protective substrate 21 is etched by silicon dry etching to form a small aperture 32 and connect it with a large aperture 31, thereby forming a flow path 11 in the protective substrate, such as... Figure 4A-C As shown. The etching conditions at this point employed a method known as the Bosch process, which uses etching and coating steps.

[0041] Along with forming the small aperture 32, a recess 18 is also formed to accommodate the vibrating diaphragm 14 and the piezoelectric element portion subsequently formed on the surface of the actuator substrate 22. The depth of the recess 18 is 100 μm to 120 μm.

[0042] Afterwards, the etching mask 42 is removed, forming the protective substrate 21, as shown below. Figure 4A-D As shown.

[0043] On the other hand, the process for fabricating the actuator substrate 22 is as follows. First, as... Figure 4A-E As shown, an actuator substrate 22 (silicon substrate) with a thickness of 600 μm is fabricated, and a vibration film forming layer is formed on the surface of the actuator substrate 22. The vibration film forming layer is formed by, for example, plasma chemical vapor deposition (CVD).

[0044] Subsequently, a hydrogen barrier film (not shown), a lower electrode (not shown), a piezoelectric film, and an upper electrode (not shown) are sequentially formed on the vibrating film forming layer. The lower and upper electrodes are formed, for example, by sputtering. The piezoelectric film is formed by a sol-gel method, but can also be formed by sputtering. This forms the piezoelectric element 15. An interlayer film and a wiring layer are formed to enable the actuator unit to be driven, and the actuator substrate 22 is formed in this manner.

[0045] Subsequently, multiple films on the actuator substrate 22 are etched to form a liquid supply path 44 that penetrates the piezoelectric film and the electrode.

[0046] Subsequently, as Figure 4A-F As shown, an adhesive with a thickness of 1.0 μm to 2.0 μm is applied to the surface of the actuator substrate 22 facing the protective substrate 21, and the actuator substrate 22 and the protective substrate 21 are bonded together in such a way that the flow path 11 and the liquid supply path 44 correspond to each other in position. As an adhesive application method, the adhesive is spin-coated onto a dry film and then transferred onto the protective substrate 21. However, the adhesive application method is not limited to this; alternatively, screen printing or photolithographic patterning can be performed using a photosensitive adhesive.

[0047] The adhesive thickness should preferably be sufficient to eliminate voids during bonding, with a thickness of 1.0 μm or more, preferably 2.0 μm, and more preferably 5.0 μm or more. Increasing the adhesive thickness will increase the amount of adhesive that climbs along the through-holes of the protective substrate 21 during bonding; however, the portion of adhesive climbing along the through-holes is trapped at the step between the small aperture 32 and the large aperture 31. Using through-holes with corners allows for control of the adhesive climb position and facilitates the trapping of adhesive climb.

[0048] Therefore, the adhesive that climbs along the corner flows to the step surface 33 formed in the step portion, thereby preventing the adhesive from blocking the flow path 11.

[0049] Subsequently, as Figure 4B-G As shown, the actuator substrate 22 is thinned by grinding from its back side. Then, as... Figure 4B-H As shown, a photoresist mask is formed on the back side, and a cavity 12 is formed by dry etching.

[0050] Subsequently, as Figure 4B-I As shown, nozzle substrate 23 is fabricated. After forming liquid jet flow path 16 in nozzle substrate 23, actuator substrate 22 and nozzle substrate 23 are bonded together, and then jet orifice 17 is formed. Then, as shown... Figure 4B-J As shown, the nozzle substrate 23 is bonded to the back of the actuator substrate 22 to cover the cavity 12 in the actuator substrate 22.

[0051] Through the above-described processes, a liquid injection head 110 according to this exemplary embodiment is manufactured.

[0052] The second exemplary embodiment will now be described. Parts similar to those in the first exemplary embodiment are indicated by the same reference numerals or symbols, and their descriptions are omitted. The description mainly focuses on the differences from the first exemplary embodiment. Figure 5 A cross-sectional view and a top view of the protective substrate 21 according to this exemplary embodiment are shown. In this exemplary embodiment, as... Figure 5As shown, the large opening 31 of the flow path 11 in the protective substrate 21 is circular in the top view. This structure allows the adhesive to climb along the corner of the small opening 32, retains excess adhesive at the stepped surface 33 of the large opening 31, and also prevents the adhesive from climbing further away from the stepped surface 33 along the flow path 11. The circular large opening 31 does not provide corners where the adhesive can easily climb, thus preventing the adhesive from climbing further.

[0053] A third exemplary embodiment will now be described. Parts similar to those in the first exemplary embodiment are indicated by the same reference numerals or symbols, and their descriptions are omitted. The description mainly focuses on the differences from the first exemplary embodiment. Figure 6 A cross-sectional view and a top view of the protective substrate 21 according to this exemplary embodiment are shown. In this exemplary embodiment, a protrusion 51 protruding toward the large opening portion 31 (second portion) is arranged on the stepped surface 33 formed in the protective substrate 21. According to this exemplary embodiment, since the protrusion 51 is present at the end point where the adhesive climbs along the corner, the adhesive exceeding the protrusion 51 is easily captured at the stepped surface 33. Although there is a possibility that the adhesive may move due to heat or other factors after bonding, the adhesive captured between the protrusion 51 and the stepped surface 33 will not move further, thereby further preventing blockage of the flow path 11.

[0054] Figures 7A to 7C A method for manufacturing the protrusion 51 is shown. The small orifice 32 and the large orifice 31 of the flow path 11 in the protective substrate 21 are formed in reverse order. That is, the large orifice 31 is formed after the small orifice 32 is formed and communicates with the small orifice 32, and the protrusion 51 is formed. Figure 7A and Figure 7B As shown, the small aperture 32 is machined to a depth of approximately 100 μm, and then a large aperture 31 is machined from the opposite surface side to communicate with the small aperture 31, thus forming a shape as shown. Figure 7C The protrusion 51 shown.

[0055] The fourth exemplary embodiment will now be described. Parts similar to those in the first exemplary embodiment are indicated by the same reference numerals or symbols, and their descriptions are omitted. The description mainly focuses on the differences from the first exemplary embodiment. Figure 8 A cross-sectional view and a top view of the protective substrate 21 according to this exemplary embodiment are shown. This exemplary embodiment is characterized by: Figure 8As shown, a plurality of small apertures 32 are formed in the protective substrate 21, and a large aperture 31 communicates with the plurality of small apertures 32. By employing a structure in which a large aperture 31 communicates with the plurality of small apertures 32, the stepped surface 33 has a large area for the adhesive that climbs along the small apertures 32 to be trapped, thereby further preventing the adhesive from clogging the flow path 11. Both the large aperture 31 and the small apertures 32 are formed by silicon reactive ion etching.

[0056] The fifth exemplary embodiment will now be described. Parts similar to those in the first exemplary embodiment are indicated by the same reference numerals or symbols, and their descriptions are omitted. The description mainly focuses on the differences from the first exemplary embodiment. Figure 9A and Figure 9B Both cross-sectional and top views of the protective substrate 21 according to this exemplary embodiment are shown. In this exemplary embodiment, the large aperture 31 of the flow path 11 is formed in the protective substrate 21 by anisotropic wet etching of silicon. Tetramethylammonium hydroxide (TMAH) is used as the etching solution for anisotropic wet etching of silicon, but alkaline solutions such as potassium hydroxide (KOH) can also be used. Figure 9A The case of using a (100) substrate as a silicon substrate is shown. Figure 9B The case using a (110) substrate is shown. Figure 9A and Figure 9B In the two substrates shown, although their shapes differ from each other, both form a large aperture 31 and then form multiple small apertures 32 on the opposite surface to connect the large aperture 31 with each of the small apertures 32. The small apertures 32 are formed by Si reactive ion etching.

[0057] When using a (100) substrate, the concern is the increased area in the planar direction and the larger size of the device chip, but the advantage is the lower substrate cost. Furthermore, the orifice area of ​​the large aperture portion 31 increases towards the back of the first surface 111, thus reducing flow resistance and facilitating ink supply. On the other hand, when using a (110) substrate, the concern is the high substrate cost, but the advantage is that small-sized device chips can be manufactured because the (110) substrate can be used along... Figure 9B The cross-sectional direction shown is formed perpendicularly. By forming the large aperture 31 using anisotropic wet etching as in the fourth exemplary embodiment, it is possible to configure the stepped surface 33 to have a large area for the adhesive to be trapped as it climbs up the corner of the small aperture 32 and the flow path 11 is not easily blocked.

[0058] The sixth exemplary embodiment will now be described. Parts similar to those in the first exemplary embodiment are indicated by the same reference numerals or symbols, and their descriptions are omitted. The description mainly focuses on the differences from the first exemplary embodiment. Figure 10A cross-sectional view and a top view of the protective substrate 21 according to this exemplary embodiment are shown. In this exemplary embodiment, as... Figure 10 As shown, multiple ( ) are formed in flow path 11. Figure 10 (There are two) Step surface 33.

[0059] The formation of multiple stepped surfaces 33 means that there are multiple portions for the adhesive to be captured as it climbs along the corners. This configuration can further prevent the adhesive from clogging the flow path 11.

[0060] This disclosure provides a flow path component that prevents adhesive from clogging the flow path formed in the substrate; and this disclosure also provides a liquid jetting head using the flow path component.

[0061] While this disclosure has been described with reference to exemplary embodiments, it should be understood that this disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims should be given the broadest interpretation to cover all variations and equivalent structures and functions.

Claims

1. A flow path component, comprising: A first substrate, wherein a flow path is formed from a first surface; and The second substrate has a second surface facing the first surface. The first substrate and the second substrate are bonded together using an adhesive between the first and second surfaces. When viewed from a direction orthogonal to the first surface, the flow path appears as a polygon with corners. The flow path includes a first portion on the first surface side and a second portion on the back side opposite to the first surface side, which communicates with the first portion. When viewed from a direction orthogonal to the first surface, the orifice area of ​​the second part is larger than that of the first part, thus the flow path is formed such that the cross-sectional area of ​​the flow path increases from the first surface toward the back surface in the cross-sectional view. The adhesive is present on the step surface between the first and second parts and at the corners of the polygon.

2. The flow path component according to claim 1, wherein, When the flow path is viewed from a direction orthogonal to the first surface, the second part appears circular.

3. The flow path component according to claim 1, wherein, A protrusion is formed on the step surface that faces the second part.

4. The flow path component according to claim 1, in, Multiple first portions are formed in the first substrate. The plurality of first parts are connected to a second part.

5. The flow path component according to claim 1, wherein, The area of ​​the orifice in the second part increases towards the back of the first surface.

6. The flow path component according to claim 1, wherein, It forms a multi-step surface.

7. The flow path component according to claim 1, wherein, When the flow path is viewed from a direction orthogonal to the first surface and from the side of the first surface, the flow path appears as a polygon.

8. A liquid injection head, comprising: A jet nozzle substrate, including a jet nozzle configured for jetting liquid; and Flow path components, including flow paths configured for supplying liquid to the injection nozzle, The flow path components include: A first substrate, wherein a flow path is formed from a first surface; and The second substrate has a second surface facing the first surface. The flow path component is formed by bonding the first substrate and the second substrate together with an adhesive between the first and second surfaces. When viewed from a direction orthogonal to the first surface, the flow path appears as a polygon with corners. The flow path includes a first portion on the first surface side and a second portion on the back side opposite to the first surface side, which communicates with the first portion. When viewed from a direction orthogonal to the first surface, the orifice area of ​​the second part is larger than that of the first part, thus the flow path is formed such that the cross-sectional area of ​​the flow path increases from the first surface toward the back surface in the cross-sectional view. The adhesive is present on the step surface between the first and second parts and at the corners of the polygon.

9. The liquid injection head according to claim 8, in, The second substrate also includes a piezoelectric element configured to generate pressure for jetting liquid. The first substrate also includes a recess surrounding the piezoelectric element.

10. The liquid injection head according to claim 8, wherein, The nozzle substrate is bonded to the second substrate using an adhesive.

11. The liquid injection head according to claim 8, wherein, When the flow path is viewed from a direction orthogonal to the first surface and from the side of the first surface, the flow path appears as a polygon.

Images