JP2023048840A - Substrate joining body and liquid discharge head - Google Patents

Abstract

To provide a substrate joining body which can suppress protrusion of an adhesive agent to a channel or the like, and can be reduced in size.SOLUTION: A substrate joining body 14 comprises: a first substrate 1 having a first plane 17; and a second substrate 2 having a second plane 18 facing the first plane 17. By arranging an adhesive agent 3 between the first plane 17 and the second plane 18, the first substrate 1 and the second substrate 2 are joined. The first substrate 1 has; a first recess 10 formed from the first plane 17 to a rear face; and a second recess 12 which communicates with the first recess 10 and is formed from the first plane to the rear face. In view from a direction orthogonal to the first plane 17, the second recess 12 is formed at a corner part of the first recess 10, and in the second recess 12, the adhesive agent 3 is arranged.SELECTED DRAWING: Figure 2

Description

The present invention relates to a substrate assembly and a liquid ejection head having the substrate assembly.

Microfabricated structures of silicon are widely used in the field of MEMS and electromechanical functional devices. One example is a liquid ejection head that ejects liquid. As an example of its use, there is a liquid ejection head of a liquid ejection recording system that performs recording by causing ejection droplets to land on a recording medium. The liquid ejection head includes a substrate provided with an energy generating element that generates energy used for ejecting liquid, and an ejection port for ejecting ink supplied from a liquid supply port provided on the substrate. . As an example of a method of manufacturing a liquid ejection head, there is a method of forming by bonding a plurality of substrates with an adhesive. In this case, the liquid ejection head has a substrate assembly in which a plurality of substrates are bonded. Bonding of a plurality of substrates is performed by pressing the substrates together while applying an adhesive. Due to this pressing, the adhesive may protrude from the joint surface and enter, for example, the flow path. If the adhesive enters the flow path, the flow path is filled with the adhesive, which may affect the print quality of the liquid ejection head.

Therefore, Japanese Patent Application Laid-Open No. 2002-100002 proposes a liquid ejection head that suppresses the overflow of an adhesive agent into ejection ports and flow paths that occurs when a plurality of substrates are joined, and improves reliability and ejection characteristics against ink clogging. ing. In this liquid ejection head, an adhesive entry region (hereinafter also referred to as an adhesive escape groove) into which the adhesive pushed out by joining can enter is provided on the joint surfaces of the plurality of substrates. As a result, the adhesive pushed out by joining the substrates enters the adhesive entry region, so that the adhesive is prevented from overflowing into the flow path or the like.

Japanese Patent Application Laid-Open No. 2001-162802

FIG. 6 is a schematic diagram showing in simplified form an example in which relief grooves for the adhesive are formed in the substrate as shown in Patent Document 1. In FIG. FIG. 6(a) is a plan view of the adhesive-applied surface that serves as the bonding surface of the first substrate 1. FIG. FIG. 6(b) is a cross-sectional view taken along line G-G' in FIG. 6(a). FIG. 6C is a plan view showing the back surface of the bonding surface of the second substrate 2 to be bonded to the first substrate 1. FIG. FIG. 6(d) is a cross-sectional view taken along line H-H' in FIG. 6(c).

As shown in FIG. 6(a), if a relief groove 13 is provided in the vicinity of the recess 10 that serves as a flow path for the liquid, the protrusion of the adhesive that occurs when the substrates are joined can be held by the relief groove 13. Accordingly, it is possible to reduce the amount of adhesive protruding into the concave portion 10 .

FIG. 7 is a schematic diagram showing the shape after bonding the first substrate 1 and the second substrate 2 shown in FIG. FIG. 7A is a plan view of the bonding surface side of the first substrate 1 after bonding. FIG. 7B is a plan view of the surface opposite to the bonding surface of the second substrate 2 after bonding. FIG. 7(c) is a cross-sectional view of the substrate assembly 14 in which the first substrate 1 and the second substrate are bonded together, taken along line I-I' in FIG. 7(b).

As shown in FIG. 7, by forming an escape groove 13 near the recess 10, the flow of the adhesive during bonding causes the adhesive to enter the escape groove and reduce the amount of adhesive pushed out into the recess 10. be able to. However, if the area of the escape groove 13 formed in the joint surface is small, the adhesive partly flows not only into the escape groove 13 but also into the concave portion 10 as shown in FIG. 7(c). In order to further suppress the overflow of the adhesive into the concave portion 10, the number of escape grooves 13 to be formed should be increased. However, increasing the number of relief grooves 13 requires a corresponding amount of space in the substrate, making it difficult to reduce the size of the substrate. As a result, it becomes difficult to miniaturize the substrate assembly.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a substrate assembly that can be miniaturized while suppressing the protrusion of an adhesive into a flow path or the like.

In order to solve the above problems, the present invention has a first substrate having a first surface and a second substrate having a second surface facing the first surface, and In the substrate bonded body in which the first substrate and the second substrate are bonded by an adhesive between the surface and the second surface, the first substrate It has a first concave portion formed from the first surface toward the back surface of the first surface, and a second concave portion communicating with the first concave portion, and is perpendicular to the first surface. When viewed from above, the second recess is formed at a corner of the first recess, and the adhesive is present in the second recess.

According to the present invention, it is possible to provide a substrate assembly that can be miniaturized while suppressing protrusion of an adhesive agent into a flow path or the like.

Schematic diagram showing a liquid ejection head. Schematic diagram showing a first substrate and a second substrate. Schematic diagram after bonding the first substrate and the second substrate. Schematic diagram showing an example of the shape and arrangement of the second recess. Schematic which shows 2nd Embodiment. Schematic diagram showing a conventional example. Schematic diagram showing a conventional example.

(First embodiment)
FIG. 1 is a schematic diagram showing the liquid ejection head 16 according to the first embodiment. FIG. 1 is a diagram showing a state in which a first substrate 1 and a second substrate 2 are overlaid. Therefore, since the substrates have not yet been pressed against each other, the first substrate 1 and the second substrate 2 are not completely bonded. FIG. 1 is a schematic diagram showing a cross-sectional view of the liquid ejection head 16. FIG. In FIG. 1, an energy generating element 5 is formed on the surface of a first substrate 1 to generate energy for ejecting liquid from an ejection port 4 . The energy generating element 5 is formed on the first substrate 1 so as to correspond to the position of the ejection port 4 . As shown in FIG. 1, the adhesive 3 is present between the bonding surface (first surface) 17 of the first substrate 1 and the bonding surface (second surface) 18 of the second substrate 2. , the first substrate 1 and the second substrate 2 are bonded together. The second surface 18 is a surface facing the first surface.

A flow path forming member 6 and a discharge port forming member 7 are formed on the first substrate 1 . The flow path forming member 6 and the ejection port forming member 7 constitute a liquid flow path 15 that communicates with the ejection port 4 . A liquid-repellent layer (not shown) is formed on the surface of the ejection port forming member 7 in order to improve the ejection performance. The liquid channel 15 is formed between the first substrate 1 and the ejection port forming member 7 .

The liquid flows through a second through channel (also referred to as a third recess) 9 formed in the second substrate 2 and a first through channel (also referred to as a first recess) formed in the first substrate 1. ) 10 to the liquid flow path 15 . Then, the liquid is given ejection energy by the energy generating element 5 and is ejected from the ejection port 4 . Dry etching, wet etching, laser processing, and the like can be used as a method for forming the through flow path. Recess 10 is formed from first surface 1 toward back surface 19 of first surface 1 .

Although silicon is suitable for the material of the first substrate 1 and the second substrate 2, silicon carbide, silicon nitride, various glasses such as quartz glass and borosilicate glass, various ceramics such as alumina and gallium arsenide, and resins may also be used. may be used.

As the adhesive 3, a material having high adhesion to the substrate is preferably used. In addition, a material with little inclusion of air bubbles and the like and high applicability is preferable, and a low-viscosity material that makes it easy to reduce the thickness of the adhesive 3 is preferable. Therefore, the material of the adhesive 3 preferably contains any resin selected from the group consisting of epoxy resin, acrylic resin, silicone resin, benzocyclobutene resin, polyamide resin, polyimide resin, and urethane resin.

As a curing method for the adhesive 3, there are a heat curing method and an ultraviolet delayed curing method. In addition, when any of the substrates has ultraviolet transmittance, an ultraviolet curing method can also be used. The bonding of the first substrate 1 and the second substrate 2 is performed by heating the substrates to a predetermined temperature in a bonding apparatus and then applying pressure for a predetermined period of time. These bonding parameters are appropriately set according to the adhesive material. Moreover, it is preferable to perform the bonding in a vacuum because it suppresses air bubbles from entering the bonding portion. In addition, it is preferable that the substrate bonded body is further heated after bonding to sufficiently promote curing. The flow path forming member 6 and the discharge port forming member 7 may be formed before joining on the first substrate, or after joining the first substrate and the second substrate to form the substrate assembly 14. may be formed.

FIG. 2 is a schematic diagram showing the first substrate 1 and the second substrate 2 before bonding the first substrate 1 and the second substrate 2 together. 2(a) is a plan view of the bonding surface on the side opposite to the discharge port 4 of the first substrate 1, FIG. 2(b) is a cross-sectional view of the BB' cross section of FIG. c) is an enlarged view within the dotted line in FIG. 2(a). FIG. 2(d) is a plan view of the second substrate 2, and FIG. 2(e) is a sectional view taken along the line C-C' of FIG. 2(d).

A first recess 10 and a second recess 12 are formed in the first substrate 1 from the first surface 17 toward the rear surface 19 of the first surface 17 . The first concave portion 10 functions as a channel through which liquid flows.

The second recess 12 is processed at the same time as the first recess 10 is formed. The space of the second concave portion 12 formed by processing functions as an accommodating portion that holds and accommodates the adhesive protruding from the bonding surface when the substrates are bonded. The second recess 12 communicates with the first recess 10 . When viewed from a direction perpendicular to the first surface 17, the second recess 12 is formed at least one of the corners where the sides of the first recess 10 intersect. Here, the "corner" includes not only corners where sides (line segments) intersect, but also rounded corners (corners R) generated during processing. In other words, deviation from the corner due to processing accuracy is allowed.

By providing the second recesses 12 at the corners of the first recesses 10, the adhesive flows vertically and horizontally. Thereby, it is possible to suppress the adhesive from flowing into the first concave portion 10 . If the second recess 12 were to be formed at a location other than the corner of the first recess 10, the adhesive would flow into the second recess 12 only from either the vertical direction or the horizontal direction. 2, the effect of flowing the adhesive to the concave portion 12 is small. Therefore, in the present invention, the second recesses 12 are formed at the corners of the first recesses 10 in order to hold more excess adhesive in the second recesses 12 .

Since the first recess 10 functions as a channel, it penetrates the first substrate 1 from the first surface 17 toward the second surface. is preferably formed so as not to penetrate the If the second concave portion 12 penetrates the first substrate 1, the adhesive entering the second concave portion 12 may flow toward the flow path forming member 6, which affects the recording quality. This is because there is a possibility that

FIG. 3A is a plan view of a bonding surface (first surface) 17 of the first substrate after bonding the first substrate 1 and the second substrate 2 using the adhesive 3. FIG. be. 3(b) is a cross-sectional view taken along line D-D' in FIG. 3(a), and FIG. 3(c) is a cross-sectional view taken along line EE' in FIG. 3(a).

When the substrates are bonded with an adhesive, the adhesive flows due to pressure during bonding. As shown in FIGS. 3(a) and 3(b), the second recesses 12 are provided at the corners of the first recesses 10, so that the surplus adhesive 3a is concentrated into the second recesses 12 and accommodated. can do. Therefore, it is possible to reduce the protrusion into the first concave portion 10, and it is possible to prevent the first concave portion 10 functioning as a flow path from being partially blocked. If the depth of the second concave portion 12 is 10 μm or more, it functions as an adhesive containing portion, and the deeper the concave portion 12 is, the more the containing volume increases, which is preferable. Further, when the second recess 12 is formed, the area for forming the second recess 12 can be reduced when viewed from the plan view shown in FIG. , the bonding substrate 14 can be miniaturized.

4A to 4J are schematic diagrams showing examples of the shape and arrangement of the second recess 12. FIG. The shape of the second recess 12 does not matter, but it is preferable that the second recess 12 has a shape including at least one vertex (corner) 8 having an angle of 90 degrees or less. This makes it easier for the adhesive to gather at the corner 8 of the second recess. Since the corner 8 of the second recess 12 is located away from the first recess 10 within the second recess 12, collecting the adhesive at the corner 8 of the second recess reduces the first It is possible to further suppress the adhesive from flowing into the recess 10 . Also, as shown in FIG. 4(j), the second recesses may be formed near the center of the first recesses 10 as long as they are formed at least at the corners of the first recesses 10 . However, if the second recess 12 is formed at a place other than the corner of the first recess 10, it becomes difficult to reduce the size of the substrate accordingly. From the standpoint of miniaturization of the substrate, it is preferable that it is formed only in the portion.

When viewed from the top view shown in FIG. 4, the opening area of the second concave portion 12 is preferably 50 μm ² or more. Thereby, the effect of accommodating the adhesive can be enhanced. However, if the second recess communicates with the adjacent first recess, the shape of the first recess itself will change significantly, so the second recess 12 will not contact the adjacent first recess. The opening area (size) and arrangement are preferable.

(Second embodiment)
A second embodiment will be described. However, portions similar to those of the first embodiment are denoted by similar reference numerals, and descriptions thereof are omitted. FIG. 5(a) is a plan view of the second substrate 2 showing the case where the second substrate 2 is provided with the fourth concave portion 11. FIG. FIG. 5(b) is a cross-sectional view of the EE' cross section of FIG. 5(a), and FIG. 5(c) is a cross-sectional view of the EE' cross section of the substrate assembly after bonding.

As shown in FIG. 5, by forming recesses (fourth recesses) 11 not only in the first substrate 1 but also in the second substrate 2, the adhesive enters the first recesses 10. can be further suppressed. In addition, it is possible to prevent the adhesive from entering the third concave portion 9 . The fourth concave portion 11 also preferably has a vertex (corner) of 90 degrees or less. As a result, the adhesive can be more collected at the apex of the fourth recess, and the flow of the adhesive to the third recess 9 can be further suppressed. Moreover, it is preferable that the fourth recess 11 is also formed only at the corner of the third recess 9 .

FIG. 5D is a top view of the second substrate 2 showing a case where the fourth recess 11 does not penetrate the second substrate 2. FIG. FIG. 5(e) is a cross-sectional view taken along the line FF' of FIG. 5(d), and FIG. 5(f) is a cross-sectional view taken along the FF' cross section of the substrate assembly after bonding. It is preferable that the fourth recess 11 does not penetrate the second substrate 2 . If the fourth recess 11 penetrates the second substrate 2 , the adhesive will flow through the fourth recess 11 to the opposite side. Therefore, it is preferable that the fourth recess 11 does not penetrate the second substrate 2 in order to retain the adhesive in the fourth recess 11 .

Furthermore, since the surface on the opposite side of the bonding surface has only the opening of the third concave portion 9, it is possible to secure a sufficient bonding area for the mounting adhesive even when used as the mounting surface, thereby ensuring close contact. A decrease in reliability can be suppressed.

A first substrate 1 is provided with an energy generating element 5 made of TaSiN, an electric circuit (not shown) for driving the energy generating element 5, and an electric connection portion (not shown) electrically connected to the electric connection substrate. prepare. The substrate consisted of silicon and was thinned by a grinder to a substrate thickness of 625 μm.

A first through channel (first recess) having a second recess 12 formed at a corner is formed in the first substrate 1 . Patterning was performed using a positive resist and a photolithographic technique in the pattern of the first concave portions as shown in FIG. 2(a). The dimension of the first recess 10 is a rectangle with a width of 150 μm and a length of 20 mm. The shape of the second recess 12 was a square of 10 μm, and the second recess 12 was formed so that the center of the second recess 12 coincided with the corner of the first recess 10 . A second recess 12 is formed at each corner of the first recess 10 . That is, four are formed in the form shown in FIG. 2 (only two second recesses 12 are shown in FIG. 2). The opening area of the formed second concave portion 12 was 75 μm ² . Using the patterned positive resist as a mask, the Bosch process is used to form the half shape of the first concave portion 10 . Etching was performed for a predetermined time so that the depth of the first concave portion 10 from the bonding surface was 450 μm. At this time, the maximum depth from the bonding surface of the second recess 12 was 315 μm. Next, only the first concave portion 10 was etched to form the first concave portion 10 so as to penetrate the first substrate 1 .

A silicon substrate having a thickness of 300 μm was prepared as the second substrate, and a second through flow path was formed in the same manner as the formation of the first substrate.

Next, a substrate for adhesive transfer was prepared, and a benzocyclobutene solution as an adhesive was spin-coated to a thickness of 3 μm. A PET film was used as a substrate for transfer. In addition, in order to volatilize the solvent after coating, baking treatment was performed at 100° C. for 5 minutes. The adhesive was transferred to the first substrate 1 by bringing the adhesive formed on the transfer base material into contact with the bonding surface (second concave portion forming surface) of the first substrate 1 while applying heat.

Next, using a bonding alignment device, the first substrate 1 and the second substrate 2 were aligned and heated in a vacuum for bonding. Bonding was performed at a degree of vacuum of 100 Pa or less and a temperature of 150°C. After the bonding was completed and cooled, the assembly was removed from the device and heat treated at 250° C. for 1 hour in an oven in a nitrogen atmosphere to cure the adhesive.

Next, a negative photosensitive resin dissolved in a PGMEA solvent is spin-coated on a PET film, dried at 100° C. in an oven to form a dry film, and transferred to the surface of the first substrate 1 where the energy generating elements are formed. and peeled off the PET film. After the formation of the dry film, the liquid flow path 15 was exposed and PEB to form a latent image. Subsequently, a dry film was laminated in the same manner, and the ejection port 4 was subjected to exposure and PEB, and the liquid flow path and the ejection port were collectively developed to produce a liquid ejection head.

REFERENCE SIGNS LIST 1 first substrate 2 second substrate 3 adhesive 10 first recess 12 second recess 14 substrate assembly 17 first surface 18 second surface

Claims (16)

a first substrate having a first surface;
a second substrate having a second surface facing the first surface;
has
In a substrate assembly in which the first substrate and the second substrate are bonded by an adhesive between the first surface and the second surface,
The first substrate has a first concave portion formed from the first surface toward the back surface of the first surface, and a first concave portion communicating with the first concave portion and extending from the first surface to the first concave portion. a second recess formed toward the back surface of the surface,
When viewed from a direction orthogonal to the first surface, the second recess is formed at a corner of the first recess,
A substrate assembly, wherein the adhesive is accommodated in the second recess. 2. The substrate assembly according to claim 1, wherein said second recess is formed only at a corner of said first recess when viewed from a direction perpendicular to said first surface. The first recess penetrates the first substrate,
3. The substrate assembly according to claim 1, wherein said second recess does not penetrate said first substrate. 4. The substrate assembly according to any one of claims 1 to 3, wherein said second recess has a vertex of 90 degrees or less. The second substrate includes: a third recess that communicates with the first recess and is formed from the second surface toward the back surface of the second surface; a fourth recess formed from the second surface toward the back surface of the second surface;
When viewed from a direction orthogonal to the second surface, the fourth recess is formed at a corner of the third recess,
5. The substrate assembly according to claim 1, wherein said fourth recess contains said adhesive. 6. The substrate assembly according to claim 5, wherein said fourth recess is formed only at a corner of said third recess when viewed from a direction perpendicular to said second surface. the third recess penetrates the second substrate,
7. The substrate assembly according to claim 5, wherein said fourth recess does not penetrate said second substrate. 8. The substrate assembly according to any one of claims 5 to 7, wherein said fourth recess has a vertex of 90 degrees or less. an ejection port for ejecting liquid;
an energy generating element that generates energy for ejecting liquid from the ejection port;
a first substrate having a first surface;
a second substrate having a second surface facing the first surface;
has
In a liquid ejection head in which the first substrate and the second substrate are bonded by an adhesive between the first surface and the second surface,
The energy generating element is formed on the back surface of the first surface of the first substrate,
The first substrate has a first concave portion formed from the first surface toward the back surface of the first surface, and a first concave portion communicating with the first concave portion and extending from the first surface to the first concave portion. a second recess formed toward the back surface of the surface,
the first recess is a flow path through which the liquid supplied to the ejection port flows;
the second substrate has a third recess that communicates with the first recess and is formed from the second surface toward the back surface of the second surface;
the third recess is a channel through which the liquid supplied to the first recess flows;
When viewed from a direction orthogonal to the first surface, the second recess is formed at a corner of the first recess,
The liquid ejection head, wherein the adhesive is accommodated in the second concave portion. 10. The liquid ejection head according to claim 9, wherein the second recesses are formed only at corners of the first recesses when viewed from a direction perpendicular to the first surface. The first recess penetrates the first substrate,
11. The liquid ejection head according to claim 9, wherein said second recess does not penetrate said first substrate. 12. The liquid ejection head according to any one of claims 9 to 11, wherein the second recess has a vertex of 90 degrees or less. the second substrate further has a fourth recess that communicates with the third recess and is formed from the second surface toward the back surface of the second surface;
When viewed from a direction orthogonal to the second surface, the fourth recess is formed at a corner of the third recess,
13. The liquid ejection head according to any one of claims 9 to 12, wherein the adhesive is accommodated in the fourth recess. 14. The liquid ejection head according to claim 13, wherein said fourth recess is formed only at a corner of said third recess when viewed from a direction perpendicular to said second surface. the third recess penetrates the second substrate,
15. The liquid ejection head according to claim 13, wherein said fourth recess does not penetrate said second substrate. 16. The substrate assembly according to any one of claims 13 to 15, wherein said fourth recess has a vertex of 90 degrees or less.

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