Flow path member, liquid ejection head

Abstract

To be able to secure rigidity of a base plate, while suppressing an adhesive from flowing into a passage.SOLUTION: A passage member 117 has a first base plate 102 and a second base plate 104, where the first base plate 102 is joined to the second base plate 104 with an adhesive 105. A groove 103 is formed annularly in at least either of a first surface 118 of the first base plate 102 and a second surface 119 of the second base plate 104, and a passage 110 is arranged inside the annularly-formed groove 103, when the first base plate 102 is viewed from a direction which is orthogonal to the first surface 118. The groove 103 has a first portion 103A formed with a first depth and a second portion 103B formed with a second depth smaller than the first depth.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] A recording device that performs recording by ejecting liquid onto a recording medium such as paper has a liquid ejection head equipped with ejection ports for ejecting liquid and energy generating elements that generate energy for ejection. The liquid ejection head further has a flow path member formed with a flow path for supplying liquid to the ejection ports and energy generating elements. The flow path member may be formed by stacking multiple substrates, each having a groove or through-hole that serves as the flow path. When multiple substrates are bonded and stacked with an adhesive, there is a risk that excess adhesive will flow into the flow path and block part of the flow path. Therefore, a method is known in which a groove that can accommodate excess adhesive (hereinafter referred to as an adhesive escape groove or escape groove) is formed on the bonding surfaces of the substrates to prevent the adhesive from flowing into the flow path.

[0003] FIG. 16 is a diagram showing an example in which no relief groove is formed in the substrate. A first substrate 102 and a second substrate 104 are bonded via an adhesive 105. Because no relief groove is formed, excess adhesive 112 flows into the flow path 110. FIG. 17 is a diagram showing an example in which relief groove 103 is formed in the first substrate 102. Because relief groove 103 is formed, excess adhesive is contained in relief groove 103, and the flow of adhesive 112 into the flow path 110 is suppressed compared to the example in FIG. 17. However, the substrate becomes thinner in the portion where the relief groove is formed by the depth of the relief groove, and the rigidity of the substrate decreases. A decrease in the rigidity of the substrate can lead to damage to the substrate.

[0004] Therefore, in Patent Document 1, in order to ensure the rigidity of the substrate, an area where no relief groove is formed (hereinafter referred to as a separation area) is provided. The presence of the separation area prevents the thickness of the substrate in that area from becoming thin, thereby ensuring the rigidity of the substrate. [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 separation portion does not have the effect of containing excess adhesive, so there is a risk that the adhesive will pass through the separation portion and flow into the flow path.

[0007] In view of the above problems, the present invention aims to provide a flow path member having an escape groove that can prevent adhesive from flowing into the flow path while ensuring the rigidity of the substrate, 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 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 joined by an adhesive between the first surface and the second surface thereof, wherein a groove is formed in an annular shape on at least one of the first surface and the second surface thereof, and when the first substrate is viewed from a direction perpendicular to the first surface thereof, the flow path is 、 formed in a ring shape The aforementioned The groove has a first portion formed at a first depth and a second portion formed at a second depth shallower than the first depth. The width of the second portion is smaller than the width of the first portion. It is characterized by: [Effects of the Invention]

[0009] According to the present invention, it is possible to ensure the rigidity of the substrate while suppressing the adhesive from flowing into the flow path. [Brief explanation of the drawings]

[0010] [Figure 1] 2A and 2B are a cross-sectional schematic view of a liquid ejection head and a top view of a first substrate. [Figure 2] Top view of the first substrate [Figure 3] Cross section AA of Figure 2. [Figure 4] Cross section BB in Figure 2. [Figure 5] CC cross section in Figure 2. [Figure 6] 3A to 3C are diagrams showing a process for forming the cross section BB of FIG. 2. [Figure 7] 3A to 3C are diagrams showing a process for forming the cross section BB of FIG. 2. [Figure 8] 2A to 2C are diagrams showing the process of forming an AA cross section. [Figure 9] 2A to 2C are diagrams showing the process of forming an AA cross section. [Figure 10] FIG. 10 is a view showing a relief groove according to a second embodiment. [Figure 11] FIG. 10 is a view showing a relief groove according to a second embodiment. [Figure 12] Cross section AA of Figure 12. [Figure 13] Cross section B-B of Figure 12. [Figure 14] FIG. 10 is a view showing a relief groove according to a third embodiment. [Figure 15] Cross section CC of Figure 13. [Figure 16] FIG. 10 is a diagram showing an example in which no relief groove is formed in the substrate. [Figure 17] 10A and 10B are diagrams showing the effect when a relief groove is formed in a substrate. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail.

[0012] (liquid ejection head) FIG. 1(a) is a schematic cross-sectional view of the liquid ejection head 101 (a cross-sectional view corresponding to the AA cross section shown in FIG. 1(b)). FIG. 1(b) is a top view of the first substrate 102, i.e., a top view as seen from a direction perpendicular to the first surface 118. The flow path member 117 of the liquid ejection head 101 is formed by bonding the first substrate 102 and the second substrate 104 with an adhesive 105. An energy generating element 106 that generates energy for ejecting liquid is formed on the surface of the first substrate 102 on the ejection port 107 side. Examples of the energy generating element include a heating resistor and a piezoelectric element.

[0013] A flow path layer 108 and a discharge port layer 109 are formed on the first substrate 102, and the liquid passes through through holes 110 and 111 formed in the second substrate 104 and the first substrate 102, and is supplied to the flow path layer 108. Then, energy is applied by the energy generating element 106, and the liquid is ejected from the discharge port 107.

[0014] Silicon is suitable as the material for the first substrate 102 and the second substrate 104. Alternatively, silicon carbide, silicon nitride, various types of glass (quartz glass, borosilicate glass, alkali-free glass, soda glass), various types of ceramics (alumina, gallium arsenide, gallium nitride, aluminum nitride), and resin can also be used as the material for the first substrate 102 and the second substrate 104.

[0015] The first substrate 102 and the second substrate 104 have through-holes 110 and 111 formed therein to supply liquid to the flow path layer 108. Methods for forming the through-holes include dry etching and wet etching. Furthermore, in order to adjust the cross-sectional height of the flow path, the members can be thinned by polishing using back-grinding or CMP (Chemical Mechanical Polishing) or by dry etching using a reactive gas. Furthermore, the members can also be thinned by wet etching using a chemical solution such as fluoronitric acid. Methods for forming through-holes include a method in which processing is performed from both sides of the substrate to penetrate the interior of the substrate, a method in which processing is performed from one side to penetrate the opposite surface, and a method in which blind holes are formed on one side and then thinned by the aforementioned back-grinding or CMP to penetrate the opposite surface.

[0016] A material with high adhesion to the substrate is preferably used for the adhesive 105. A material with high applicability and little air bubble contamination is also preferred, as is a low-viscosity material that allows the adhesive 105 to be easily thinned. The adhesive 105 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 105 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.

[0017] An example of a method for applying the adhesive 105 is an adhesive transfer method using a substrate. Specifically, a transfer substrate is prepared, and the adhesive is applied thinly and uniformly onto the transfer substrate by spin coating or slit coating. Thereafter, the adhesive surface of the first substrate 102 is brought into contact with the applied adhesive, thereby transferring the adhesive only to the adhesive surface of the first substrate 102. The size of the transfer substrate is preferably equal to or larger than the size of the first substrate 102. Suitable substrates include silicon, glass, and films such as PET, PEN, and PI. Methods for directly applying the adhesive to the first substrate 102 include screen printing and dispense coating.

[0018] The first substrate 102 and the second substrate 104 are bonded by heating the substrates to a predetermined temperature in a bonding device and then applying pressure for a predetermined time. These bonding parameters are set appropriately depending on the adhesive material. Furthermore, bonding in a vacuum is preferable to prevent air bubbles from entering the bonded area.

[0019] If the adhesive 105 is a thermosetting type, it may be heated in a bonding device until it hardens. Alternatively, the substrate assembly may be removed after bonding and heated separately in an oven or the like to accelerate hardening. If the adhesive 105 is an ultraviolet-delay type, the adhesive 105 is irradiated with a specified amount of ultraviolet light before bonding and then bonded. After bonding, it is preferable to further heat the substrate assembly to sufficiently accelerate hardening. If the adhesive 105 is an ultraviolet-curing type, after bonding the substrates together, it is hardened by irradiating the adhesive 105 with a specified amount of ultraviolet light through a substrate that is ultraviolet-transparent. After bonding, it is preferable to further heat the substrate assembly to sufficiently accelerate hardening.

[0020] The flow path layer 108 and the discharge port layer 109 may contain epoxy resin, acrylic resin, urethane resin, etc. Examples of epoxy resin include bisphenol A type, cresol novolac type, and alicyclic epoxy resin, examples of acrylic resin include polymethyl methacrylate, and examples of urethane resin include polyurethane.

[0021] The formation method involves laminating a dry film resist, which is a film substrate coated with a photocurable resin, onto the first substrate 102. The dry film resist is then exposed and developed to pattern the flow path layer 108. Next, the discharge port layer 109 is similarly patterned using the dry film resist. Finally, the unexposed portions are developed en bloc to form the flow path layer 108 and the discharge port layer 109. When using a dry film resist, it is preferable to add a resin binder to the resin layer to increase its rigidity. A resin binder is a resin with a higher molecular weight than the base resin (such as the epoxy resin described above). It is added to increase the weight-average molecular weight of the resin layer to improve the cohesive strength and softening point of the film. Increasing the rigidity of the resin layer makes it easier to transfer the resin layer onto a through-hole (liquid supply port) in the substrate.

[0022] It is also possible to form the flow path layer 108 and the discharge port layer 109 before the through-holes are formed in the first substrate 102. In this case, a resin layer can be formed directly on the first substrate 102 by spin coating, and then the flow path layer 108 and the discharge port layer 109 can be formed.

[0023] Furthermore, the timing for forming the flow path layer 108 and the ejection port layer 109 may be either before or after the first substrate 102 and the second substrate 104 are bonded together.

[0024] (First embodiment) In this embodiment, as shown in FIG. 1, a groove (relief groove) 103 that prevents the adhesive from spilling into the flow path is formed on the first surface 118 of the first substrate 102. The relief groove 103 may also be formed on the second surface 119 of the second substrate 104. The second surface 119 is the surface of the second substrate 104 that faces the first surface 118. The relief groove 103 may also be formed on both the first surface 118 and the second surface 119. Therefore, it is sufficient that the relief groove 103 is formed on at least one of the first surface 118 or the second surface 119. As shown in FIG. 1(b), a plurality of flow paths 110 are formed on the first surface 118. The relief groove 103 is formed continuously in a ring shape so as to surround the flow path 110. In other words, when the first substrate 102 is viewed from a direction perpendicular to the first surface 118, the flow path 110 is disposed inside the groove 103 formed in an annular shape. The shape of the flow path 110 is rectangular. The relief groove has portions of different depths. That is, the relief groove 103 has a first portion 103A formed at a first depth and a second portion 103B formed at a second depth shallower than the first depth. The first portion 103A with a deeper relief groove can accommodate more adhesive, while the second portion 103B with a shallower relief groove can suppress a decrease in substrate rigidity. The depth of the relief groove refers to the depth from the first surface 118 when the relief groove 103 is formed on the first surface 118. When the relief groove 103 is formed on the second surface 119, the depth refers to the depth from the second surface 119.

[0025] Furthermore, because second portion 103B of the shallow relief groove and first portion 103A of the deep relief groove are continuously connected, when the amount of adhesive that cannot be contained in second portion 103B of the shallow relief groove flows in, the adhesive flows from second portion 103B to first portion 103A. Therefore, the presence of shallow second portion 103B does not reduce the ability of the relief groove as a whole to receive excess adhesive.

[0026] The clearance groove of this embodiment can ensure the strength of the substrate more than clearance grooves formed at a uniform depth everywhere, because the boundary between the first portion 103A and the second portion 103B has a stepped shape, which increases the strength against external stress.

[0027] 2 shows a top view of the first substrate 102. The channels 110 of the first substrate are arranged at a narrow pitch, and if the adhesive between the channels is allowed to protrude, the relief grooves 103 are desirably arranged along the outer edge of the channel group.

[0028] FIG. 3 shows the AA cross section of FIG. 2, FIG. 4 shows the BB cross section of FIG. 2, and FIG. 5 shows the CC cross section of FIG. 2. The process for forming the AA cross section of FIG. 2 is shown in FIGS. 8 and 9, and the process for forming the BB cross section of FIG. 2 is shown in FIGS. 6 and 7. To form the relief groove 103, an exposure mask 113 having a half-tone portion 115 is used in the process of forming a mask resist 114 on the first substrate 102 as shown in FIG. 6. The half-tone portion 115 is used in a position corresponding to the opening of the relief groove 103. A semi-transparent film is provided in the half-tone portion, which is half-exposed, leaving the resist film. In addition to half-tone masks, there is also a gray-tone mask, which creates a half-exposed state using slits below the exposure resolution.

[0029] After patterning the mask resist, the flow path is formed by dry etching. The remaining film is thinned by dry etching until the substrate surface is exposed, at which point etching of the substrate begins. In other words, the part exposed to the halftone part can form a shallower groove than the other normally exposed parts.

[0030] The depth of the relief groove can be adjusted by adjusting the initial film thickness of the mask resist, the transmittance of the semi-transparent film of the halftone mask, or the like.

[0031] The relief groove 103 formed as described above has portions with different depths within one continuous relief groove. The shallow relief groove portion 103B leaves a large amount of substrate in the cross-sectional direction of the substrate, and can provide higher rigidity than relief grooves in which all portions are formed deep.

[0032] To ensure board rigidity, it is desirable to set the depth of the relief groove so that the ratio H2 / H1 is 1 / 2 or less, where H1 is the depth of the first portion 103A and H2 is the depth of the second portion 103B. In other words, the second depth, which is the depth of the second portion 103B, is less than half the first depth, which is the depth of the first portion 103A. While a shallow relief groove's ability to accommodate excess adhesive decreases, because deep relief grooves are formed continuously, adhesive that cannot be accommodated in the shallower relief grooves flows to deeper portions, and the overall capacity of the relief grooves is not reduced. Furthermore, in this embodiment, the bottom of the relief groove is formed parallel to the joining surfaces (first surface, second surface) as shown in FIG. 5. Forming the relief grooves parallel maximizes the volume of the relief groove.

[0033] (Second embodiment) A second embodiment will be described with reference to FIGS. 10 to 13. In the second embodiment, the depth of the relief groove 103 is changed by changing the width of the relief groove. When the relief groove is formed by dry etching, the etching rate during processing changes depending on the opening width of the mask resist. When the opening width is narrow, the etching rate is lower than when the opening width is wide. This is called the microloading effect.

[0034] As shown in FIG. 10, when the clearance groove has narrow portions 103B and wide portions 103A, the clearance groove depth is shallower in the narrow portions than in the wide portions, as shown in the AA cross section in FIG. 12 and the BB cross section in FIG. 13. Furthermore, since the corners of the flow channel 110 shown in FIG. 10 are prone to stress concentration and breakage when force is applied to the substrate, the clearance groove in the area surrounded by the extension lines of the wall surfaces at the corner where the flow channel walls intersect is shallow. In other words, the portion of the clearance groove in the area surrounded by the extension lines of the two sides constituting the corner of the flow channel 110 and the outer edge of the first surface is the shallow second portion. This ensures rigidity in the cross-sectional direction of the substrate and makes it less likely to break even when force is applied to the substrate. Furthermore, to avoid stress concentration at the corners of the clearance groove, it may be rounded as shown in FIG. 11.

[0035] (Third embodiment 3) A third embodiment will be described with reference to Figures 14 and 15. In this third embodiment, a silicon substrate with a (110) crystal orientation is used as the substrate 101. The substrate 101 is wet-etched using a strong alkaline solution, such as TMAH or KOH, to form a flow path. Figure 15 shows a CC cross section of Figure 14. When a (110) substrate is used, a slope made of a (111) plane is formed on the side of the relief groove, resulting in shallow and deep portions. In other words, the bottom of the first portion 103A is parallel to the first surface 118, while the bottom of the second portion 103B is a slope that is inclined relative to the first surface 118. In this way, the slope connecting the portions with different depths also has the effect of making it easier for excess adhesive that has entered the shallow portion to flow into the deep relief groove. [Example]

[0036] Example 1 A first substrate 102 is prepared, on which are formed energy generating elements 106 made of TaSiN and used to eject droplets as shown in Fig. 1, an electric circuit (not shown) that drives the energy generating elements 106, and an electric connection part (not shown) that is electrically connected to an electric connection board. The substrate is made of silicon, and is thinned to a thickness of 625 µm using a grinding device.

[0037] A flow path 110 and an escape groove 103 are formed on the first substrate 102. As shown in FIG. 6, a mask resist 114 was formed on the first substrate 102 by spin coating using a positive resist. The film thickness was set to 8 μm. Next, the mask resist 114 was patterned using photolithography. An exposure mask 113 was used in this process, with a halftone portion 115 provided in a portion corresponding to the escape groove. The halftone portion 115 forms a semi-transparent film so that the transmittance is 40% compared to the transparent portion. After exposure, the mask resist was developed with a developer containing TMAH to form the desired opening pattern. After development, the mask resist film thickness in the exposed halftone portion was 3.2 μm.

[0038] Next, the Bosch process was used to form the flow channel 110 in the first substrate 102. The flow channel 102 and the clearance groove 103 were simultaneously processed so that the depth of the flow channel 110 was 450 μm. The etching rate for silicon was 7 μm / min, and the processing time was 65 minutes. The etching rate for the mask resist was 0.08 μm / min, so 40 minutes after the start of etching, the mask resist 114 disappeared, and etching of the shallow clearance groove portion 113B began. As a result, the depth of the flow channel 110 was 450 μm, the deep clearance groove 113A was 400 μm, and the shallow clearance groove 113B was 150 μm. After peeling and cleaning the mask resist 114, the flow channel was formed from the energy generating element formation surface using a similar process, and the clearance groove formation surface was penetrated into the formed flow channel.

[0039] A 300 μm silicon substrate was prepared as the second substrate 104, and a protective tape was attached to the surface opposite to the etching surface. Etching was performed from one side until the substrate was penetrated, forming a flow path.

[0040] Next, a substrate for adhesive transfer was prepared. Benzocyclobutene solution was spin-coated to a thickness of 3 μm as the adhesive. PET film was used as the substrate for transfer. After coating, a baking treatment was performed at 100°C for 5 minutes to volatilize the solvent. The adhesive formed on the substrate for transfer was transferred to the first substrate 102 by contacting it with the bonding surface (surface with the relief groove) of the first substrate 102 while applying heat.

[0041] Next, the first substrate 102 and the second substrate 104 were aligned using a bonding alignment device and heated in a vacuum to bond them together. Bonding was performed at a vacuum level of 100 Pa or less and a temperature of 150°C. After bonding was completed and cooling was performed, the substrate was removed from the device and subjected to heat treatment at 250°C for 1 hour in an oven in a nitrogen atmosphere to harden the adhesive.

[0042] Next, a negative photosensitive resin dissolved in PGMEA solvent was spin-coated onto the PET film and dried at 100°C in an oven to form a dry film, which was then transferred to the energy generating element-forming surface of the first substrate 102, and the PET film was peeled off. After the dry film was formed, the flow path was exposed and PEB was performed to create a latent image. Next, a dry film was laminated in the same way, and the nozzle was exposed and PEB was performed to develop the flow path and nozzle together, completing the liquid ejection head.

[0043] Example 2 In the second embodiment, the width of the relief groove is changed, and the depth is changed by forming the groove by dry etching.

[0044] Specifically, the width of deep relief groove 103A is set to 100 μm, and the width of shallow relief groove 103B is set to 10 μm, as shown in Fig. 10. As a result, when etching was performed using the Bosch process to form flow channel 110 with a target depth of 450 μm, deep relief groove 103A was formed to a depth of 430 μm, and shallow relief groove 103B was formed to a depth of 80 μm.

[0045] Example 3 In Example 3, a silicon substrate with a (110) surface orientation is used as the first substrate, and an escape groove 103 is formed by wet etching using an alkaline etching solution, thereby changing the depth of the escape groove depending on the (111) surface formed within the escape groove.

[0046] TMAH was used as the alkaline etching solution, and etching was performed at a temperature of 80° C. A CC cross section of the relief groove 103 is shown in Figure 18. A slope was formed in the relief groove on the (111) plane 116, and shallow relief groove 103B and deep relief groove 103A were formed continuously. [Explanation of symbols]

[0047] 102 first substrate 103 Groove (relief groove) 103A First Part 103B Second Part 104 Second substrate 105 Adhesive 118 First Side 119 Second Side

Claims

1. a first substrate having a flow path formed on a first surface; a second substrate having a second surface opposite to the first surface; and In a flow path member in which the first substrate and the second substrate are joined by an adhesive between the first surface and the second surface, a groove is formed in an annular shape on at least one of the first surface and the second surface; When the first substrate is viewed from a direction perpendicular to the first surface, the flow path is disposed inside the groove formed in an annular shape, The groove has a first portion formed at a first depth and a second portion formed at a second depth shallower than the first depth, A flow path member, wherein the width of the second portion is smaller than the width of the first portion.

2. The flow path member according to claim 1 , wherein the second depth is equal to or less than half of the first depth.

3. The flow path member according to claim 1 or 2, wherein the bottoms of the first portion and the second portion are parallel to the first surface or the second surface.

4. a bottom of the first portion is parallel to the first surface or the second surface; The flow path member according to claim 1 or 2, wherein a bottom of the second portion is an inclined surface inclined with respect to the first surface or the second surface.

5. a plurality of the flow channels are formed on the first surface, The flow path member according to claim 1 , wherein the plurality of flow paths are arranged inside the groove when the first substrate is viewed from a direction perpendicular to the first surface.

6. 6. A flow path member according to claim 1, wherein when the first substrate is viewed from a direction perpendicular to the first surface, the shape of the flow path is rectangular, and the portion of the groove existing within an area surrounded by the extension lines of two sides constituting a corner of the flow path and the outer edge of the first surface is the second portion.

7. a discharge port for discharging a liquid; an energy generating element that generates energy for ejecting liquid from the ejection port; A flow path member according to any one of claims 1 to 6; In a liquid ejection head having The liquid ejection head is characterized in that the flow path member is a member for supplying liquid to the ejection port.

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