Flow path member and liquid ejection head

Abstract

To provide a passage member which makes deformation, cracks, and damage less likely to occur, and to provide a liquid discharge head using the passage member.SOLUTION: A passage member 13 has: a first substrate 1 in which a passage 3 is formed on a first surface 11; and a second substrate 2 having a second surface 12 facing the first surface 11. An adhesive 4 is applied to a space between the first surface 11 and the second surface 12 to join the first substrate 1 and the second substrate 2 to each other. Multiple recessed parts 5 are formed in at least one of the first surface 11 and the second surface 12. A shape of each of the recessed parts 5 is roughly isotropic when the recessed part 5 is viewed from a direction orthogonal to the first surface 11.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] In recent years, in the manufacture of functional devices such as MEMS (microelectromechanical systems) such as pressure sensors and acceleration sensors, and microfluidic devices, devices consisting of flow path members made by bonding substrates together using adhesives have been produced. MEMS is an abbreviation for Micro Electro Mechanical System. One example is a liquid ejection head that ejects liquid. When a flow path member is applied to a liquid ejection head, it functions as a flow path member for supplying liquid to ejection ports that eject the liquid.

[0003] An example of a liquid ejection head is an inkjet recording head. An inkjet recording head has an energy generating element that provides energy for ejecting ink. In addition, an ejection port member is formed on the surface of a substrate, and the ejection port member has multiple ejection ports formed therein for ejecting ink. Through holes are formed in the substrate as ink flow paths, and ink flows through the through holes from one side of the substrate to the other side. The through holes and the ejection ports are connected, and ink that passes through the through holes is ejected from the ejection ports by the force applied by the energy generating element. Examples of energy generating elements include elements such as heating elements that boil ink by applying electrical current and heating, and elements such as piezoelectric elements that apply pressure to liquid by using volume changes.

[0004] Patent Document 1 discloses a flow path member used in such a liquid ejection head, which is formed by laminating multiple substrates each having holes or grooves that serve as flow paths. The substrates are also formed with recesses (adhesive escape grooves) that prevent the adhesive used when joining the substrates from flowing into the holes or grooves that serve as flow paths. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-47620 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the adhesive relief grooves described in Patent Document 1 are formed with a certain directionality, which causes areas of weak strength in the substrate in the direction of the directionality, and deformation, cracks, or breakage of the substrate or flow path member along the relief grooves may occur during handling during the manufacturing process.

[0007] In view of the above problems, an object of the present invention is to provide a flow path member that is resistant to deformation, cracks, and breakage, and a liquid ejection head using the same. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a flow path member having a first substrate having a flow path opening formed on a first surface thereof, and a second substrate having a second surface opposite to the first surface, wherein the first substrate and the second substrate are bonded together by an adhesive between the first surface and the second surface thereof, wherein a plurality of recesses are formed on at least one of the first surface and the second surface thereof, When the recess is viewed from a direction perpendicular to the first surface, the recess has a shape in which two n-gons (n ​​is an integer greater than or equal to 4) of the same shape are arranged with their centers of gravity overlapped, and only one of the two n-gons is rotated by 90 degrees, or when the recess is viewed from a direction perpendicular to the first surface, the recess has a shape in which two triangles of the same shape are arranged with their centers of gravity overlapped, and only one of the two triangles is rotated by 180 degrees, When the recess is viewed from a direction perpendicular to the first surface, n-gon If the short side of the smallest rectangle that touches the outer edge of is A and the long side is B, the ratio of the short side A to the long side B is 1 / 2≦A / B < 1, When the recess is viewed from a direction perpendicular to the first surface, the ratio of the short side A to the long side B of the smallest rectangle that contacts the outer edge of the triangle is 1 / 2≦A / B<1, where A is the short side and B is the long side. It is characterized by the following. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a flow path member that is resistant to deformation, cracks, and breakage, and a liquid ejection head using the same. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] 1 is a cross-sectional view showing a comparative example of a flow path member; [Figure 4] FIG. [Figure 5] FIG. [Figure 6] Top view of the first surface. [Figure 7] Top view of an isotropic recess. [Figure 8] FIG. 10 is a top view of the first surface according to the second embodiment. [Figure 9] FIG. 10 is a top view of the first surface according to the second embodiment. [Figure 10] FIG. 10 is a top view of the first surface according to the second embodiment. [Figure 11] FIG. 10 is a top view showing microcracks occurring in recesses. [Figure 12] FIG. 10 is a top view of the first surface according to the second embodiment. [Figure 13] FIG. 10 is a top view of the first surface according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification, a case where two substrates are bonded together to form a flow path member is illustrated, but the present invention is not limited to this and can also be applied to a case where multiple substrates are combined.

[0012] (First embodiment) 1 illustrates two substrates that form a flow path member according to this embodiment. An opening 3 is provided on a first surface 11 of a first substrate 1. Examples of the opening 3 include an opening that penetrates the first substrate 1 in the thickness direction and an opening that does not penetrate the first substrate 1. The opening 3 that penetrates the first substrate 1 becomes a flow path through which ink flows.

[0013] Similarly, openings 3 are provided on the second surface 12 of the second substrate 2 shown in FIG. 1 . The second surface 12 is the surface opposite the first surface 11. The openings 3 formed in the second substrate 2 also function as channels through which ink flows. Here, the openings 3 are exemplified as openings that penetrate the first substrate 1 and the second substrate 2 when the first substrates 1 and 2 are bonded together. The openings 3 in the first substrate 1 and the second substrate 2 are not limited to those shown in the figure, and their size and depth can be set as desired depending on the application. Furthermore, multiple openings 3 in the first substrate 1 and the second substrate 2 may be arranged within the substrate depending on the application, or they may be arranged in any direction. For example, in the case of a liquid ejection head, the penetrating openings among the openings 3 are connected to ejection ports that eject liquid such as ink. This allows them to be used as channels through which liquid such as ink flows or as pressure chambers that apply volumetric changes to liquid using energy-generating elements such as heater elements and piezoelectric elements. Among the openings 3, non-penetrating openings can be used as spaces for forming electrical connection parts and energy generating elements such as heater elements and piezoelectric elements. Furthermore, a plurality of ejection ports are arranged in the substrate, and flow paths, electrical connection parts and energy generating elements can be arranged according to the number and positions of the ejection ports, and openings 3 can be formed arbitrarily in the first substrate 1 and the second substrate 2 accordingly.

[0014] An adhesive 4 is provided on the first substrate 1, and the first substrate 1 and the second substrate 2 are bonded together via the adhesive 4. In other words, the adhesive 4 is provided between the first surface 11 of the first substrate 1 and the second surface 12 of the second substrate 2, bonding the first substrate 1 and the second substrate 2 together to form a flow path member 13. Furthermore, a recess 5 is formed on the first surface 11 of the first substrate 1 near the opening 3. In FIG. 1, the recess 5 is formed on the surface to which the adhesive 4 is applied, but this is not limited thereto. It may be formed on a surface of the substrate where no adhesive is applied, as shown in FIG. 2, or may be formed on both surfaces as necessary. That is, the recess 5 may be formed on at least one of the first surface 11 or the second surface 12. Furthermore, when the first substrate 1 has the opening 3 and the second substrate 2 has the recess 5, it is preferable that the recess 5 of the second substrate 2 be located near the opening 3 of the first substrate 1 after the first substrate 1 and the second substrate 2 are bonded together.

[0015] In this embodiment, the joining of a first substrate 1 and a second substrate 2 is described, but the flow path member of the present invention may be formed from multiple substrates, and a flow path member formed from two or more substrates can also be formed by joining them in the same manner via an adhesive.

[0016] Suitable materials for the first substrate 1 and the second substrate 2 include metals such as stainless steel and nickel, silicon substrates, ceramics such as alumina and zirconium, and glass. There are no particular limitations on the method for forming the openings 3 in the first substrates 1 and 2, but examples include dry etching, wet etching, laser, and sandblasting, depending on the material.

[0017] A material with high adhesion to the substrate is preferably used as the adhesive 4. A material with high applicability and little air bubble contamination is also preferred, as is a low-viscosity material that allows for easy thinning of the adhesive. The adhesive preferably contains a resin selected from the group consisting of epoxy resin, acrylic resin, silicone resin, benzocyclobutene resin, polyamide resin, polyimide resin, and urethane resin. Examples of curing methods for the adhesive 4 include a thermal curing method and a delayed ultraviolet curing method. If one of the substrates is ultraviolet-transparent, an ultraviolet curing method can also be used.

[0018] Known methods such as spin coating, slit coating, transfer, ink jet printing, and screen printing can be used to form the adhesive on the first substrate 1 and the second substrate 2. If the openings 3 and recesses 5 are already formed when the adhesive 4 is formed, it is preferable to select an adhesive formation method that prevents the adhesive from entering the openings 4 and recesses 5.

[0019] The first substrate 1 and the second substrate 2 are bonded together by attaching the substrates together via the adhesive 4 and applying pressure. The bonding may be performed under atmospheric pressure, or under reduced pressure to prevent the inclusion of air bubbles. If necessary, heating may be performed to reduce the viscosity of the adhesive, making it easier to flow, thereby filling voids during bonding and preventing the inclusion of air bubbles.

[0020] Fig. 3 is a diagram showing a comparative example of the present invention. When bonding a first substrate 1 and a second substrate 2, excess adhesive may overflow into the opening 3, as shown in Fig. 3. Taking a liquid ejection head as an example, if the opening is a flow path through which a liquid such as ink flows, the flow path may become narrow or blocked, impairing the flow of the liquid. Alternatively, if an energy generating element or an electrode for electrical connection is provided within the opening, the adhesive may come into contact with these elements, resulting in a decrease in functionality or a malfunction when making an electrical connection.

[0021] Fig. 4 is a diagram showing the first substrate 1 and second substrate 2 shown in Fig. 1 bonded together. By forming recesses 3 in the substrates, excess adhesive 4 can be guided into recesses 5 as shown in Fig. 4. This makes it possible to prevent adhesive from spilling out 7 into opening 3.

[0022] Next, the recess 5 will be specifically described using a plan view. FIG. 5 is a top view of the recess 5 as viewed from a direction perpendicular to the first surface 11, showing a comparative example. FIG. 6 is a top view of the recess 5 in this embodiment. As shown in FIG. 5, if the recess 5 formed in the substrate is formed with a directionality 8, the strength of the substrate decreases along the directionality 8 of the recess 5, and deformation, cracks, or breakage of the substrate may occur along the directionality 8 of the recess 5 during handling during the manufacturing process.

[0023] Therefore, in the present invention, the recesses 5 are formed so that the planar shape of the recesses 5 is approximately isotropic, as shown in Fig. 6. This makes it possible to prevent the occurrence of locations where the strength of the substrate is reduced in a specific direction, and to prevent deformation, cracks, and breakage of the substrate.

[0024] Next, the shape of the recesses 5 in the present invention will be specifically described. FIG. 7 is a schematic diagram showing a plan view (top view) of the recesses 5. In the present invention, an isotropic recess 5 that minimizes directionality means that the planar shape of each recess 5 does not have an extremely biased shape, as shown in FIG. 5. Specifically, when the smallest rectangle 9 that contacts the planar shape (outer edge) of each recess 5 is drawn as shown in FIG. 7(a), the ratio of the short side A μm to the long side B μm is preferably 1:1≦A:B≦1:2. More preferably, it is 1:1≦A:B≦1:1.5, and even more preferably, it is 1:1≦A:B≦1:1.3. Therefore, in the present invention, "approximately isotropic" means that the ratio of the short side A μm to the long side B μm is 1:1≦A:B≦1:2.

[0025] On the other hand, in order to prevent the adhesive from flowing into the opening 3, it is preferable to form multiple recesses 5 so as to surround the outer edge 6 of the opening 3 when viewed from above, as shown in FIG. 6 . However, even if the recesses 5 are formed so as to surround the outer edge 6 of the opening 3, if there are large gaps between adjacent recesses in the direction along the outer edge 6 (hereinafter referred to as the outer edge direction), there is a risk that the adhesive will flow into the opening 3 through the gaps. Therefore, it is preferable to reduce the gaps between the recesses in the outer edge direction. One possible method for reducing the gaps between the recesses is to form the recesses 5 at high density. However, this increases the number of recesses 5 formed, which may result in a decrease in the strength of the substrate. Therefore, it is preferable to increase the A:B ratio of the recesses 5 and form multiple recesses 5 so that the long side B is oriented along the outer edge 6 of the opening 3. This reduces the number of recesses 5 required to reduce the gaps between adjacent recesses in the outer edge direction when the recesses 5 surround the outer edge 6 of the opening 3. This prevents a decrease in the strength of the substrate while preventing the adhesive from flowing into the opening 3. That is, the recess 5 in the present invention preferably has a ratio of 1:1≦A:B. For example, in the case of a circular shape, an elliptical shape can be suitably used.

[0026] Furthermore, as shown in Fig. 7(b), the recess 5 of this embodiment can be applied even if it has a shape in which multiple recesses are rotated and overlapped so that the centers of the multiple recesses coincide, as long as the smallest circumscribing rectangle 9 is within the above-mentioned range when drawn. In this case, it is preferable to adopt a planar shape of each overlapping recess that falls within the scope of the present invention, as shown in Fig. 7(a). Fig. 7(b) shows an example in which two recesses are overlapped.

[0027] When the planar shape of the recess is polygonal, the vertices of the polygon are the cause of stress concentration, so it is preferable that they are formed with curvature. Specifically, the radius of curvature of the vertex is preferably 1 / 4 or more, more preferably 1 / 3 or more, of the length A μm of the short side of the smallest circumscribing rectangle 9. Furthermore, the planar shape is more preferably a circle or an ellipse that satisfies the scope of the present invention than a polygon.

[0028] The recesses 5 can be formed using a general mask to provide control over their shape, depending on the material of the substrate and the method for forming the recesses 5. Furthermore, it is preferable to perform patterning using a photoresist or the like according to the size of the recesses 5 and the processing accuracy required, and then perform processing using dry etching or the like. Furthermore, it is preferable to form the recesses 5 simultaneously with the formation of the openings 3 in the first substrate 1 or the second substrate 2, but they may also be formed separately from the openings 3, and there are no particular limitations on this.

[0029] (Second embodiment) A second embodiment will now be described. FIG. 8 is a top view of the first surface 11 in this embodiment. In FIG. 8, the recesses 5 are regularly arranged (the intervals between each recess are the same). The intervals between the recesses 5 depend on the thickness and material of the substrate and the depth of the recesses 5. However, even if the directionality of the recesses 5 is eliminated, there is a concern that the rigidity will decrease if the recesses 5 are too close together. Furthermore, if the recesses 5 are spaced apart, there is a concern that the number of paths for the adhesive 4 to flow into the openings 3 will increase, resulting in a greater overflow into the openings 3. Therefore, it is preferable that the spacing be at least 1 to 100 μm or more. Furthermore, to further ensure the strength of the substrate, the recesses 5 may be formed into a hexagonal honeycomb structure.

[0030] FIG. 9 shows an example in which the recesses 5 are irregularly arranged so that the spacing between adjacent recesses 5 varies depending on the location. In this case, it is more preferable to offset the positions of adjacent recesses 5 so that the extensions of the sides of adjacent recesses 5 do not completely overlap. Alternatively, as shown in FIG. 10, the recesses 5 may be rotated so that they face in different directions. In other words, the recesses are formed at an angle relative to the other recesses adjacent to them. For example, as shown in FIG. 11, if a minute crack 10 occurs along the side of a recess 5, the cracks may connect on the same side as shown in FIG. 11(a). However, by offsetting the positions of adjacent recesses 5 as shown in FIG. 11(b) or by rotating adjacent recesses 5 as shown in FIG. 11(c), it is possible to make it difficult for the cracks to connect with each other. This prevents cracks from connecting and becoming larger, thereby suppressing a decrease in rigidity and preventing the substrate from breaking or cracking.

[0031] 12 and 13 are diagrams showing modified examples of this embodiment. As shown in Fig. 12, recesses 5 of different sizes may be arranged as needed. Also, as shown in Fig. 13, recesses 5 of different shapes may be arranged. For example, by making the recesses 5 smaller and arranging them more closely near the opening 3 or by changing the shape, it is possible to prevent a decrease in rigidity and prevent breakage or cracking.

[0032] Up to this point, the embodiments of the recess 5 according to the present invention have been described, but they are not limited to the contents shown in the drawings, and each of them can be combined as necessary. [Explanation of symbols]

[0033] 1 First board 2 Second board 3 Opening (flow path) 4. Adhesive 5 recess 11 First Side 12 Second Side 13 Flow path components

Claims

1. a first substrate having a first surface on which an opening of a flow channel is formed; 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 an adhesive between the first surface and the second surface, a plurality of recesses are formed on at least one of the first surface and the second surface; When the recess is viewed from a direction perpendicular to the first surface, the recess has a shape in which two identical n-gons (n ​​is an integer greater than or equal to 4) are arranged with their centers of gravity overlapped, and only one of the two n-gons is rotated 90 degrees, or when the recess is viewed from a direction perpendicular to the first surface, the recess has a shape obtained by rotating only one of two triangles of the same shape by 180 degrees from a state in which the centers of gravity of the two triangles are overlapped, When the recess is viewed from a direction perpendicular to the first surface, the ratio of the short side A to the long side B of the smallest rectangle that contacts the outer edge of the n-gon is: 1 / 2≦A / B<1 and When the recess is viewed from a direction perpendicular to the first surface, the ratio of the short side A to the long side B of the smallest rectangle that is in contact with the outer edge of the triangle is: 1 / 2≦A / B<1 A flow path member characterized by:

2. a first substrate having a first surface on which an opening of a flow channel is formed; 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 an adhesive between the first surface and the second surface, a plurality of recesses are formed on at least one of the first surface and the second surface; When the recess is viewed from a direction perpendicular to the first surface, the ratio of the short side A to the long side B of the smallest rectangle that contacts the outer edge of the recess is: 1 / 2≦A / B≦1 and The flow path member is characterized in that the recessed portion has a hexagonal shape.

3. The ratio of the short side A to the long side B is 1 / 1.5≦A / B<1 The flow path member according to claim 1 or 2, wherein

4. The ratio of the short side A to the long side B is 1 / 1.3≦A / B<1 The flow path member according to claim 1 or 2, wherein

5. 5. The flow path member according to claim 1, wherein the recess is formed so that the long side B is oriented along an outer edge of the opening.

6. 6. The flow path member according to claim 1, wherein when the recess is viewed from a direction perpendicular to the first surface, the radius of curvature of the apex of the recess is 1 / 4 or more of the length of the short side A.

7. The flow path member according to claim 6 , wherein the radius of curvature is equal to or greater than one-third of the length of the short side A.

8. A flow path member described in any one of claims 1 to 7, wherein the shortest distance between two recesses that are arranged closest to each other among the plurality of recesses is 1 to 100 μm.

9. The flow path member according to claim 1 , wherein the recesses are all arranged at the same intervals.

10. The flow path member according to claim 1 , wherein the recesses are arranged at different intervals depending on the location.

11. 11. The flow path member according to claim 1, wherein when the recess is viewed from a direction perpendicular to the first surface, none of the sides of the recess is positioned on the same straight line as any of the sides of other recesses adjacent to the recess.

12. The flow path member according to claim 11 , wherein when the recess is viewed from a direction perpendicular to the first surface, the recess is formed at an angle with respect to other recesses adjacent to the recess.

13. The flow path member according to claim 1 , wherein the plurality of recesses include recesses of different sizes when the recesses are viewed from a direction perpendicular to the first surface.

14. The flow path member according to claim 1 , wherein the plurality of recesses include recesses having different shapes when the recesses are viewed from a direction perpendicular to the first surface.

15. a discharge port for discharging a liquid; A flow path member according to any one of claims 1 to 14; and The liquid ejection head is characterized in that the flow path of the flow path member is a flow path for supplying liquid to the ejection port.

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