Liquid ejection head

Abstract

To provide a liquid discharge head which can inhibit flow of a contact material protruding from a joint surface.SOLUTION: A liquid discharge head 4 has: a first substrate including a structure; and a second substrate joined to the first substrate through an adhesive 40. The first substrate is formed with: a joint surface 24 joined to the second substrate through the adhesive 40; and a non-joint surface 29 which is not joined to the second substrate. A recessed part 32 is formed at an area, which is located between a joint end part 25, i.e. a structure side end part of the joint surface 24, and the structure, of an area of the non-joint surface 29.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head. [Background technology]

[0002] A recording device that discharges liquid to perform recording is equipped with a liquid discharge head that discharges liquid from a discharge port. When a liquid discharge head is formed by bonding multiple substrates with an adhesive, excess adhesive may protrude from the bonded surfaces, resulting in a decrease in yield and a deterioration in device characteristics.

[0003] Therefore, Patent Document 1 presents a method in which a groove (recess) is formed on the bonding surface to which the adhesive is applied, and the excess adhesive that is generated when the substrates are pressed together during bonding can be contained in the recess. By containing the excess adhesive in the recess, it is possible to prevent the adhesive from overflowing from the bonding surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-207072 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, if the adhesive cannot be contained in the recess and spills out from the bonding surface, the recess is formed only on the bonding surface, so the adhesive cannot be prevented from flowing thereafter. Therefore, there is a risk that the spilled adhesive may adhere to structures such as pressure generating elements, affecting the recording quality.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above problems, an object of the present invention is to provide a liquid ejection head capable of suppressing the flow of a contact material that protrudes from a bonding surface. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a liquid ejection head having a first substrate having a structure and a second substrate bonded to the first substrate via an adhesive, wherein the first substrate has a bonding surface bonded to the second substrate via the adhesive and a non-bonding surface not bonded to the second substrate, and a recess is formed in an area of ​​the non-bonding surface between the structure and a bonding end portion, which is the end portion of the bonding surface facing the structure. Effect of the Invention

[0008] According to the present invention, it is possible to provide a liquid ejection head capable of suppressing the flow of the contact material that protrudes from the joining surface. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a liquid ejection head. [Diagram 2] 4A to 4C are diagrams showing a process for bonding each substrate; [Diagram 3] 4A to 4C are diagrams showing a process for bonding each substrate; [Figure 4] FIG. 6 is a schematic view showing a recess according to a second embodiment. [Diagram 5] FIG. 13 is a schematic view showing a recess according to a third embodiment. [Figure 6] FIG. 13 is a schematic view showing a recess according to a third embodiment. [Figure 7] FIG. 13 is a schematic view showing a recess according to a third embodiment. [Figure 8] FIG. 13 is a schematic view showing a recess according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail. In this application, the structure refers to a pressure generating element 21 (FIG. 1), a discharge port 31 (FIG. 1), and a communication port 5 (FIG. 7) described later. In this application, a substrate on which the above-mentioned structure is formed is referred to as a first substrate, and a substrate bonded to the first substrate by an adhesive is referred to as a second substrate. That is, in some cases, the pressure generating substrate 2 described in detail below is regarded as the first substrate and the flow path substrate 1 is regarded as the second substrate, while in other cases, the discharge port substrate 3 is regarded as the first substrate and the pressure generating substrate 2 is regarded as the second substrate.

[0011] (First embodiment) (Liquid ejection head) Fig. 1(a) is a schematic perspective view of a liquid ejection head 4 according to this embodiment. Fig. 1(b) is a cross-sectional view taken along the line AA' in Fig. 1(a). As shown in Fig. 1, the liquid ejection head 4 is mainly composed of a flow path substrate 1, a pressure generating substrate 2, and an ejection port substrate 3, and each substrate is bonded with an adhesive 40 (Fig. 2).

[0012] The flow path substrate 1 is formed of a substrate such as silicon, ceramic, or resin. A through hole is formed in the flow path substrate 1 by dry etching, wet etching, physical processing, or the like, and this through hole becomes a supply flow path 11 for supplying liquid onto the pressure generating element. Furthermore, the flow path substrate 1 is formed with a space (pressure generating chamber 12) in which a pressure generating element 21 that generates pressure for discharging liquid from a discharge port 31 is provided. When the pressure generating element 21 is a piezoelectric element, this space enables the piezoelectric element to be displaced, and liquid is discharged from the discharge port 31 by the pressure caused by the displacement of the piezoelectric element.

[0013] The pressure-generating substrate 2 is formed of a substrate such as silicon, ceramic, or resin. The pressure-generating substrate 2 is provided with a pressure-generating element 21, electrodes connected to the pressure-generating element 21, a circuit (not shown) for selectively supplying power to a specific electrode, and the like. The pressure-generating element 21 is made of polycrystalline ceramic such as lead zirconate titanate (PZT) to which piezoelectricity has been imparted, a resistance heating element made of an inorganic thin film, or the like. A liquid chamber 22 is formed which communicates with the supply flow path 11 of the flow path substrate 1 and is adjacent to the pressure-generating element 21.

[0014] The ejection port substrate 3 is formed of a substrate such as silicon, ceramic, or resin. The ejection port substrate 3 is also formed with an ejection port 31 for ejecting liquid. The ejection port 31 communicates with the liquid chamber 22, and the pressure generated by the pressure generating element 21 is transmitted to the liquid chamber 22, causing the liquid to be ejected from the ejection port 31.

[0015] The adhesives used to bond the substrates together include epoxy resins, organic silicon materials, metal pastes, etc., either alone or in combination, and the material is selected taking into consideration adhesive strength, durability when in contact with liquid, etc. These adhesives are applied to the bonding surfaces of the substrates, and the substrates are chemically or physically bonded together by applying energy such as heat or pressing.

[0016] When multiple substrates are bonded together to create a liquid ejection head, the order in which the substrates are bonded and the surfaces to which adhesive is applied can be freely determined as long as the layering relationship of the three substrates is appropriate. That is, the pressure-generating substrate 2 is bonded between the flow path substrate 1 and the ejection port substrate 3.

[0017] (Bonding of substrates) The process of bonding each substrate will be described with reference to FIG. 2 and FIG. 3. FIG. 2(a) is a schematic diagram of a state where an adhesive is applied to the surface of the flow path substrate 1 facing the pressure-generating substrate 2. FIG. 2(b) is a schematic diagram of the flow path substrate 1 and the pressure-generating substrate 2 bonded from the state shown in FIG. 2(a). FIG. 2(c) is an enlarged view of region B shown in FIG. 2(b). FIG. 3(a) is a schematic diagram of a state where an adhesive is applied to the surface of the pressure-generating substrate 2 facing the ejection port substrate 3 in the state where the flow path substrate 1 and the pressure-generating substrate 2 are bonded. FIG. 3(b) is a schematic diagram of the state where the ejection port substrate 3 is bonded to the pressure-generating substrate 2 from the state shown in FIG. 3(a). FIG. 3(c) is an enlarged view of region C shown in FIG. 3(b).

[0018] As shown in FIG. 2(a), an adhesive 40 is applied to a surface (bonding surface) 24 of the flow path substrate 1 on the pressure-generating substrate 2 side, which is bonded to the pressure-generating substrate 2. A recess 23 is formed in advance on a non-bonding surface 29 of the pressure-generating substrate 2, which is a surface that is not bonded to the flow path substrate 1. Next, the flow path substrate 1 and the pressure-generating substrate 2 are bonded by hot pressing (FIG. 2(b)). The thickness of the adhesive at the substrate interface after bonding, i.e., the bonding surface 24, is typically several μm or less, depending on the bonding conditions, and excess adhesive 41 overflows from a bonding end 25 where the bonding surface 24 terminates, and spreads wet on the pressure-generating substrate. Here, the bonding end 25 refers to the end of the bonding surface 24 on the structure side. A pressure-generating element 21 (also called a structure) is present on the pressure-generating substrate beyond the bonding end 25. A recess 23 is formed on the pressure-generating substrate 2 between the bonding end 25 and the pressure-generating element 21. The surface tension of the adhesive acts at the edge 26 of the joining end of the recess 23, preventing the excess adhesive 41 from moving beyond. This makes it possible to prevent the excess adhesive 41 from coming into contact with the pressure-generating element 21. As a result, it is possible to prevent the adhesive that has overflowed from the joining end 25 from adhering to the pressure-generating element 21 from affecting the recording quality. In FIG. 2, the pressure-generating substrate 2 corresponds to the first substrate, and the flow path substrate 1 corresponds to the second substrate.

[0019] Next, as shown in FIG. 3(a), the discharge port substrate 3 to which the recess 23 is bonded in advance is prepared. An adhesive 40 is applied to the surface of the pressure generating substrate 2 on the discharge port substrate 3 side. At this time, the recess 23 is formed in advance on the discharge port substrate 3 beside the discharge port 31. Then, the discharge port substrate 3 is bonded to form the liquid discharge head 4. As in FIG. 2, when the excess adhesive 41 overflows from the bonding end 25 and spreads wet on the discharge port substrate, the adhesive 41 may adhere to the discharge port 31 (also called a structure). Therefore, as described above, by forming the recess 23 on the discharge port substrate 3, the surface tension of the adhesive acts on the step part of the recess 23, and it is possible to suppress the overflowing adhesive from flowing beyond. This makes it possible to prevent the excess adhesive 41 from blocking the discharge port 31, and therefore the influence on the recording quality can be suppressed. In addition, as an effect of restricting the movement of the overflow to the vicinity of the discharge port, the volume change of the liquid chamber near the discharge port 31 is suppressed, and there is also an effect of reducing the influence on the discharge amount characteristics. In FIG. 3, the ejection port substrate 3 corresponds to the first substrate, and the pressure generating substrate 2 corresponds to the second substrate.

[0020] In addition, even if the adhesive overflows and exceeds the step of the recess, the adhesive is contained within the recess, which has the effect of preventing the adhesive from adhering to the structure.

[0021] Second Embodiment The second embodiment will be described with reference to FIG. 4. The same reference numerals are used for the same parts as in the first embodiment, and the description will be omitted. This embodiment is characterized by the shape of the recess for suppressing the flow of the adhesive. The following description will be given using the recess 23 formed in the pressure generating substrate 2, but the same can be applied to the recess formed in the ejection port substrate 3. FIG. 4(a) is a schematic diagram showing the flow path substrate 1 and the pressure generating substrate 2 in this embodiment. FIG. 4(b) is an enlarged view of the region D shown in FIG. 4(a). In the following description, the formation angle θ of the recess 23 refers to the angle between the side wall 6 of the recess 23 and the main surface 7 of the substrate, that is, the angle θ shown in FIG. 4(b).

[0022] As shown in FIG. 4(b), it is preferable that the forming angle θ of the recess 23 is less than 90 degrees. If the adhesive overflows a lot, the adhesive overflows due to surface tension at the edge 26 of the recess 23, and when this comes into contact with the inner wall of the recess 23, the damming effect is lost and the adhesive flows into the inside of the recess 23. The smaller the forming angle θ of the recess 23, the less likely the overflow will come into contact with the inner wall, and the easier it is to maintain the damming effect. More preferably, the forming angle θ of the recess 23 is 70 degrees or less, and even more preferably 50 degrees or less. However, if the forming angle θ of the recess 23 is too small, the formation of the recess becomes complicated, so the forming angle θ of the recess 23 is preferably 30 degrees or more.

[0023] (Third embodiment) The third embodiment will be described with reference to Figs. 5, 6 and 7. The same reference numerals are used for the same parts as in the first embodiment, and the description will be omitted. This embodiment is characterized by the position where the recess 23 is formed and the dimensions of the recess 23. Fig. 5(a) is a schematic diagram showing a flow path substrate 1 and a pressure generating substrate 2 in this embodiment. Fig. 5(b) is an enlarged view of region E shown in Fig. 5(a).

[0024] It is preferable to form the recess 23 at a position as far away from the pressure generating element 21 as possible. This is because, when the pressure generating element 21 is a PZT (piezoelectric element), the grooved recess 23 is more likely to be subjected to the stress of vibration due to the PZT, and the resonance frequency may change, and the closer the recess 23 is to the PZT, the more likely the vibration state may be affected. As shown in FIG. 5, the influence can be reduced by arranging the recess 23 in a range where there is as little influence as possible, for example, so that it is located closer to the joint end 25 than the intermediate position 27 between the joint end 25 and the end 33 of the pressure generating element 21 on the joint end 25 side. More preferably, when the area between the joint end 25 and the end 33 of the pressure generating element 21 is divided into three equal parts, it is preferable to form the recess 23 in the area closest to the joint end 25 among the three equal parts.

[0025] For the same reason, it is preferable to keep the width 28 of the recess 23 at or below a width 30 that is less than half the distance between the joint end 25 and the pressure generating element 21, to minimize the effect on the device characteristics. By reducing the width 28 of the recess 23, it is possible to minimize the decrease in strength around the recess 23. Note that the width 28 of the recess 23 refers to the length of the short side of the long and short sides of the recess 23 (see FIG. 8).

[0026] FIG. 6(a) shows an example of a recess 23 formed in the ejection port substrate 3. FIG. 6(b) shows an enlarged view of the region F shown in FIG. 6(a). The deeper the recess 23, the better, in consideration of the case where the rise caused by the surface tension of the adhesive collapses and the adhesive spreads inside the recess. On the other hand, the shallower the recess, the better, in consideration of the mechanical strength around the recess and the effect on the device characteristics described above. In consideration of these, the depth 36 of the recess 23 (depth from the bonding surface 24) is preferably 0.01 times or more and 0.80 times or less with respect to the thickness 35 of the substrate on which the recess is formed. Furthermore, it is more preferable that the depth 36 of the recess 23 is 0.01 times or more and 0.50 times or less, in terms of the mechanical strength around the recess, etc.

[0027] FIG. 7(a) shows an example in which a recess 23 is formed between the supply flow path 11 and the joint surface 24. FIG. 7(b) shows an enlarged view of the region G shown in FIG. 7(a). As shown in FIG. 7, when the supply flow path 11 and the liquid chamber 22 communicate with each other through a communication port 5 (also called a structure) having a diameter smaller than the flow path diameter of the supply flow path 11, even if the amount of excess adhesive 41 is small, if the communication port 5 is partially blocked, the flow resistance of the liquid increases, which is not preferable. Therefore, in this embodiment, as shown in FIG. 7, a recess 23 is formed between the joint end 25 and the communication port 5. By forming such a recess 23, it is possible to prevent the excess adhesive 41 from blocking the communication port 5.

[0028] (Fourth embodiment) The fourth embodiment will be described with reference to FIG. 8. The same reference numerals are used for the same parts as in the first embodiment, and the description will be omitted. This embodiment is characterized by the region where the recess 23 is formed. FIG. 8(a) is a plan view of the flow path substrate 1 and the pressure generating substrate 2 in a bonded state, as viewed from the pressure generating substrate side. FIGS. 8(b) to (d) are enlarged views of the region H shown in FIG. 8(a). Note that, as an example, FIG. 8 illustrates a form in which the recess 23 is formed between the pressure generating element 21 and the bonding end 25, but this embodiment is not limited to this. That is, the same applies to the case where the recess 23 is formed between the discharge port 31 and the bonding end 25, as shown in FIG. 3(c).

[0029] As shown in Figures 8(b) to (d), the planar arrangement of the recesses 23 may be any arrangement in the region between the joining end portion 25 and the pressure-generating element 21. Therefore, as shown in Figure 8(b), the recesses 23 may be formed continuously so as to surround the periphery of the pressure-generating element 21, or as shown in Figure 8(c), the recesses 23 may be formed intermittently. Alternatively, as shown in Figure 8(d), a plurality of recesses 23 may be formed so as to surround the periphery of the pressure-generating element 21. EXAMPLES

[0030] The liquid ejection head 4 was fabricated by bonding a flow path substrate 1, a pressure generating substrate 2, and an ejection port substrate 3. The flow path substrate 1 is provided with a supply flow path 11 with an opening size of 100 μm×100 μm on a silicon substrate with a thickness of 500 μm, and a pressure generating chamber 12 with a size of 150 μm×2000 μm and a depth of 100 μm. The pressure generating substrate 2 is provided with a PZT element made of lead zirconate titanate with a size of 100 μm×1900 μm on the silicon substrate together with electrodes and a driving circuit. The pressure generating substrate 2 is also provided with a liquid chamber 22 with a size of 150 μm×2500 μm and a depth of 100 μm, and a recess with a width of 10 μm is formed so as to surround the periphery of the PZT element. The ejection port substrate 3 is provided with an ejection port 31 with a diameter of 20 μm on silicon with a thickness of 10 μm. These three substrates were bonded together with a thermosetting adhesive whose main component was benzocyclobutene resin containing silicon. When the ejection port 31 of the liquid ejection head was observed, no clogging due to excess adhesive was found.

[0031] For comparison, a liquid ejection head was produced in which the pressure-generating substrate 2 and the ejection port substrate 3 did not have recesses 23 formed, but the other structures were made with the same dimensions. As a result, blockage of the ejection port 31 due to overflow of adhesive occurred at a rate of 0.5%. [Explanation of symbols]

[0032] 2,3 First board 2,3 Second board 4. Liquid ejection head 23 Recess 24 Joint surface 29 Non-bonded surface 25 Joint end 40 Adhesive

Claims

1. a first substrate having a structure; a second substrate bonded to the first substrate via an adhesive; In a liquid ejection head having a bonding region bonded to a second substrate via the adhesive and a non-bonding region not bonded to the second substrate are formed on a first surface of the first substrate, a recess is formed in a region between a joining end portion, which is an end portion of the joining region on the structure side, and the structure, in the non-joining region; The liquid ejection head is characterized in that the recess is formed closer to the joint end than a midpoint between the joint end and an end of the structure on the joint end side.

2. the liquid ejection head includes an ejection port substrate having an ejection port for ejecting liquid, a pressure generation substrate having a pressure generation element for generating pressure for ejecting liquid from the ejection port, and a flow path substrate having a flow path for supplying liquid onto the pressure generation element, the first substrate is the pressure generating substrate, the second substrate is the flow path substrate, The liquid ejection head according to claim 1 , wherein the structure is the pressure generating element.

3. the liquid ejection head includes an ejection port substrate having an ejection port for ejecting liquid, a pressure generation substrate having a pressure generation element for generating pressure for ejecting liquid from the ejection port, and a flow path substrate having a flow path for supplying liquid onto the pressure generation element, the first substrate is the ejection port substrate, the second substrate is the pressure generating substrate, The liquid ejection head according to claim 1 , wherein the structure is the ejection port.

4. the liquid ejection head includes an ejection port substrate having an ejection port for ejecting liquid, a pressure generation substrate having a pressure generation element for generating pressure for ejecting liquid from the ejection port, and a flow path substrate having a flow path for supplying liquid onto the pressure generation element, a communication port having a diameter smaller than a flow path diameter of the flow path is formed in the pressure generating substrate, the flow channel of the flow channel substrate is connected to the communication port of the pressure generation substrate, the first substrate is the pressure generating substrate, the second substrate is the flow path substrate, The liquid ejection head according to claim 1 , wherein the structure is the communication hole.

5. 5. The liquid ejection head according to claim 1, wherein the recess is formed at an angle of less than 90 degrees.

6. A first substrate having a structure; a second substrate bonded to the first substrate via an adhesive; In a liquid ejection head having a bonding region bonded to a second substrate via the adhesive and a non-bonding region not bonded to the second substrate are formed on a first surface of the first substrate, a recess is formed in a region between a joining end portion, which is an end portion of the joining region on the structure side, and the structure, in the non-joining region; A liquid ejection head, wherein the recess is formed at an angle of less than 90 degrees.

7. 7. The liquid ejection head according to claim 1, wherein the recess is formed at an angle of 70 degrees or less.

8. 8. The liquid ejection head according to claim 1, wherein the recess is formed at an angle of 50 degrees or less.

9. 9. The liquid ejection head according to claim 1, wherein the recess is formed at an angle of 30 degrees or more.

10. A liquid ejection head as described in any one of claims 1 to 9, wherein the recess is formed within the area closest to the joint end among the three equal parts when the area between the joint end and the end of the structure on the joint end side is divided into three equal parts.

11. A first substrate having a structure; a second substrate bonded to the first substrate via an adhesive; In a liquid ejection head having a bonding region bonded to a second substrate via the adhesive and a non-bonding region not bonded to the second substrate are formed on a first surface of the first substrate, a recess is formed in a region between a joining end portion, which is an end portion of the joining region on the structure side, and the structure, in the non-joining region; A liquid ejection head in which the recess is formed within the area closest to the joint end among the three equal parts when the area between the joint end and the end of the structure on the joint end side is divided into three equal parts.

12. 12. The liquid ejection head according to claim 1, wherein a width of the recess is equal to or less than half the distance between the joint end and the structure.

13. A liquid ejection head according to any one of claims 1 to 12, wherein the depth of the recess from the bonding region on the first surface is 0.01 times or more and 0.80 times or less the thickness of the first substrate in which the recess is formed.

14. A liquid ejection head according to any one of claims 1 to 13, wherein the depth of the recess from the bonding region on the first surface is 0.01 times or more and 0.50 times or less the thickness of the first substrate in which the recess is formed.

15. The liquid ejection head according to claim 9 , wherein, when the first substrate and the second substrate are viewed in plan view, the recess is formed so as to continuously surround the periphery of the structure.

16. The liquid ejection head according to claim 9 , wherein, when the first substrate and the second substrate are viewed in plan view, the recess is formed so as to discontinuously surround the periphery of the structure.

17. The liquid ejection head according to claim 9 , wherein a plurality of the recesses are formed surrounding the periphery of the structure when the first substrate and the second substrate are viewed in plan view.

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