JP2023060997A - Substrate joint body and liquid discharge head - Google Patents

Abstract

To provide a substrate joint body that can suppress a substrate from enlarging in size while securing strength of the substrate.SOLUTION: A substrate joint body 14 comprises a first substrate 1 having a first flow path 8a and a second flow path 8b, and a second substrate 2 jointed to the first substrate 1 through an adhesive 3. The first substrate 1 further has concave parts 12 communicating with the first flow path 8a. When viewed from a direction orthogonal to the first substrate 1, the concave parts 12 are formed in a region 17 between the first flow path 8a and the second flow path 8b, from the first flow path 8a toward the second flow path 8b, where the adhesives 3 are stored in the concave parts 12.SELECTED DRAWING: Figure 2

Description

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

Structures obtained by microfabrication of silicon or the like are widely used in the field of MEMS and functional devices of electric machines. 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 area (hereinafter referred to as an adhesive escape groove or simply an escape groove) into which the adhesive pushed out by joining can enter is provided on the joint surface of a plurality of substrates. . As a result, the adhesive pushed out by joining the substrates enters the escape groove, so that the adhesive is suppressed from overflowing into the flow path or the like.

JP-A-2001-162802

FIG. 7 is a schematic diagram showing a substrate assembly 14 according to a comparative example of the invention. FIG. 7(a) is a plan view showing the first substrate 1, and is a plan view showing the surface to be bonded to the second substrate 2. FIG. FIG. 7(b) is a cross-sectional view taken along the line H-H' of FIG. 7(a). FIG. 7C is a plan view showing the second substrate 2, which is a plan view of the surface opposite to the surface bonded to the first substrate 1. FIG. FIG. 7(d) is a cross-sectional view taken along line I-I' in FIG. 7(c). FIG. 7(e) is a sectional view of a substrate assembly 14 formed by joining the first substrate 1 and the second substrate 2 shown in FIGS. 7(b) and 7(d).

As shown in FIG. 7A, an escape groove 13 is formed between the first flow path 8a and the second flow path 8b formed in the first substrate 1. As shown in FIG. Since the escape groove 13 can hold the adhesive protruding from the bonding surface due to the pressure applied when the first substrate 1 and the second substrate 2 are bonded, the first flow path 8a and the second flow path 8a It is possible to suppress the adhesive from flowing into the flow path 8b.

Since the escape groove 13 is formed by digging the substrate, the strength of the substrate around the escape groove 13 is lowered. Therefore, if the escape groove 13 is formed as shown in FIG. 7, the strength of the first substrate 1 is reduced in the direction in which the escape groove 13 extends (the Y direction). As a method of avoiding this, a method of increasing the distance in the X direction between the first flow path 8a and the escape groove 13 and the distance in the X direction between the second flow path 8b and the escape groove 13 can be considered. When the distance in the X direction between the first flow path 8a or the second flow path 8b and the escape groove 13 is increased, a region in which the substrate is not dug expands around the escape groove 13, thereby improving the strength of the substrate. It is for However, if the distance between each flow path and the escape groove 13 is increased, the first substrate 1 becomes large in the X direction, and the size of the first substrate 1 may be increased.

In view of the above problems, it is an object of the present invention to provide a substrate assembly capable of securing the strength of the substrates while suppressing an increase in the size of the substrates in which escape grooves for adhesive are formed.

In order to solve the above problems, the present invention provides a first substrate having a first flow channel and a second flow channel formed adjacent to the first flow channel; and a second substrate bonded via an adhesive, wherein the first substrate further has a recess communicating with the first flow path, the first substrate When viewed in a direction perpendicular to the substrate, the recess extends from the first flow channel toward the second flow channel in a region between the first flow channel and the second flow channel. and the adhesive is accommodated in the recess.

According to the present invention, it is possible to provide a substrate assembly capable of suppressing an increase in the size of the substrates while ensuring the strength of the substrates in which relief grooves for the adhesive are formed.

FIG. 2 is a perspective view showing a liquid ejection head; Schematic diagram showing a first substrate and a second substrate. Schematic diagram showing a first substrate and a second substrate in a second embodiment. Schematic which shows the 1st board|substrate in other embodiment. Schematic which shows the 1st board|substrate in other embodiment. Schematic which shows the 1st board|substrate in other embodiment. It is a schematic diagram showing a conventional example.

(First embodiment)
FIG. 1 is a schematic diagram showing a configuration example of a liquid ejection head 15 according to the first embodiment of the invention. In FIG. 1, a first substrate 1 and a second substrate 2 are bonded together with an adhesive 3 interposed therebetween. FIG. 1A is a top view of the liquid ejection head 15. FIG. FIG. 1(b) is a top view of the bonding surface side of the second substrate 2. FIG. FIG.1(c) is sectional drawing of the AA' cross section of FIG.1(a)(b). In FIG. 1(c), on the surface of the first substrate 1 are provided energy generating elements 5, particularly electrothermal conversion elements and piezoelectric elements for ejecting liquid, and for driving the ejection energy generating elements. Wiring and the like (not shown) may be included. The energy generating element 5 is formed on the first substrate 1 so as to correspond to the position of the ejection port 4 . An ejection port forming member 6 and an electrode 7 are formed on the first substrate 1 .

The liquid passes through the first flow path 8 a formed in the second substrate 2 and the first substrate 1 , is given ejection energy by the energy generating element 5 , and is ejected from the ejection port 4 . Liquid not ejected from the ejection port 4 is recovered from the second flow path 8b. Therefore, the first channel 8a functions as a supply channel for supplying liquid to the ejection port, and the second channel 8b functions as a recovery channel for recovering the liquid from the ejection port. The second flow path 8b is a flow path formed adjacent to the first flow path 8a.

Although silicon is suitable for the material of the first and second substrates, 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. .

Dry etching, wet etching, laser processing, or the like can be used as a method for forming the first flow path 8a and the second flow path 8b penetrating the substrate. Moreover, in order to adjust the height of the flow path in the cross-sectional direction, the member can be thinned by back grinding or polishing by CMP.

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. 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 step of forming the discharge port forming member 6 on the first substrate 1 may be performed before or after bonding the substrates.

FIG. 2(a) is a plan view of the bonding surface, which is the surface of the first substrate 1 opposite to the ejection port 4. FIG. FIG. 2(b) is a cross-sectional view taken along line B-B' in FIG. 2(a). 2(c) is a cross-sectional view taken along line C-C' in FIG. 2(a), and FIG. FIG. 2(e) is a cross-sectional view taken along line DD' of FIG. 2(d). FIG. 2(f) is an enlarged view within the dotted line in FIG. 2(a). FIG. 2(g) is a cross-sectional view taken along line B-B' in FIG. FIG. 2(h) is a cross-sectional view taken along the line C-C' of FIG. 2(a) after the first substrate 1 and the second substrate 2 are bonded via the adhesive 3.

In the present invention, when viewed from a direction perpendicular to the first substrate (when viewed from the plan view shown in FIG. 2(a)), from the first channel 8a toward the second channel 8b A concave portion (an escape groove for the adhesive) 12 is formed at the end. The concave portion 12 functions as an escape groove for the adhesive. The region in which the recess 12 is formed is the region 17 between the first channel 8a and the second channel 8b. With such a configuration, there is an area 16 in which no recesses 12 are formed between the first flow path 8a and the second flow path 8b. Since the region 16 is not formed with a recess, the region 16 has high rigidity, and as a result, the strength necessary for the first substrate 1 can be ensured by the region 16 portion. Therefore, it is not necessary to increase the size of the substrate in order to secure the strength. Therefore, according to the present invention, it is possible to secure the strength of the substrate while suppressing the increase in the size of the substrate.

A general clearance groove as shown in FIG. 7 is formed independently without communicating with the flow path (the first flow path 8a and the second flow path 8b). In this case, if the substrate is heated with air bubbles in the adhesive in the escape groove, the air bubbles in the adhesive may expand and the bonding reliability may deteriorate. On the other hand, according to the present invention, even if air bubbles enter the adhesive, it is possible to Air bubbles can escape into the passage. As a result, deterioration in adhesion reliability can also be suppressed.

Prior to bonding the first substrate 1 and the second substrate 2 together, the first flow path 8a and the second flow path 8b communicate with each other via the recess 12 . However, when the liquid flows inside the first flow path 8a and the second flow path 8b, the liquid is prevented from flowing from the first flow path 8a through the recess 12 into the second flow path 8b. It is preferable to If the liquid flows from the first flow path 8a to the second flow path 8b through the recess 12, for example, a flow rate different from the flow rate assumed in advance flows through the flow path, causing problems. Sometimes. Therefore, after bonding the first substrate 1 and the second substrate 2 together, it is preferable that the first channel 8a and the second channel 8b do not communicate with each other. Therefore, in this embodiment, as shown in FIG. 2(h), it is preferable that the concave portion 12 is filled with an adhesive after bonding the substrates. As a result, the first flow path 8a and the second flow path 8b become independent.

The recess 12 is formed in a region 17 between the first flow path 8a and the second flow path 8b and is formed from the first flow path 8a toward the second flow path 8b. If there is, it does not matter where it is arranged or how many it is arranged. An appropriate number may be arranged in the first channel 8a and the second channel 8b so that excess adhesive does not flow.

The concave portion 12 may be processed at the same time when the first flow path 8a and the second flow path 8b are processed, or may be processed separately. Also, the number of recesses 12 to be arranged is not limited. It is preferable to take into account the amount of the adhesive 3 used for bonding the substrates and adjust accordingly.

(Second embodiment)
A second embodiment will be described. However, portions similar to those of the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted. FIG. 3A is a plan view of the bonding surface of the first substrate 1 opposite to the ejection port 4. FIG. FIG. 3(b) is a cross-sectional view taken along line EE' of FIG. 3(a). 3(c) is a cross-sectional view taken along the line FF' of FIG. 3(a), and FIG. 3(d) is a plan view of the second substrate 2 opposite to the bonding surface. FIG. 3(e) is a cross-sectional view taken along line GG' of FIG. 3(d). FIG. 3(f) is an enlarged view within the dotted line in FIG. 3(a). FIG. 3(g) is a cross-sectional view taken along line EE' of FIG. FIG. 3(h) is a cross-sectional view taken along line FF' of FIG.

This embodiment is characterized in that the recess 12 communicates only with one of the flow paths (the first flow path 8a in the figure). In the first embodiment, the recess 12 communicates with both the first flow path 8a and the second flow path 8b. Therefore, in order to make the first flow path 8a and the second flow path 8b independent flow paths, it was necessary to close the concave portion 12 with an adhesive. However, in this embodiment, since the recess 12 communicates only with the first flow path 8a, the first flow path 8a and the second flow path 8b are formed independently from the beginning. become. Therefore, it is not necessary to cover the concave portion 12 with the adhesive 3, which leads to an improvement in yield.

As described above, in the first embodiment, it was necessary to block the recess 12 with the adhesive 3 in order to make the first flow path 8a and the second flow path 8b independent of each other. Therefore, it is necessary to make the depth of the recess 12 shallow so that the recess 12 is easily filled with the adhesive 3 . Here, the depth of the concave portion 12 means the depth from the surface (main surface) 18 (FIG. 3C) of the first substrate 1 to which the adhesive is applied. On the other hand, in the present embodiment, since the first flow path 8a and the second flow path 8b are independent in advance, it is not necessary to block the concave portion 12 with an adhesive. Therefore, the recess 12 can be formed deep.

As the depth of the concave portion 12 becomes deeper, the accommodation volume of the adhesive 3 becomes larger, and a larger amount of the protruding adhesive can be accommodated. However, forming the concave portion 12 too deeply may reduce the strength of the substrate. Therefore, the depth of the concave portion 12 is preferably 0.5 to 0.9 times the thickness (length in the Z direction) of the first substrate 1 . As a result, it is possible to suppress a decrease in the strength of the substrate while increasing the capacity of the adhesive 3 .

(Other embodiments)
Other embodiments will be described. Descriptions of the same parts as in the above-described embodiment are omitted. FIGS. 4 to 6 are diagrams corresponding to FIG. 2(f), showing a form in which recesses are also formed in the second flow path 8b. A recessed portion (second recessed portion) formed in the second flow path 8 is referred to as a recessed portion 12'. FIG. 4 shows an example in which the recess 12 formed in the first channel 8a and the recess 12' formed in the second channel 8b are symmetrically formed. In FIG. 4, the recess 12 and the recess 12' are symmetrical about the center line of the region 17 as the axis of symmetry. Since the concave portion 12 and the concave portion 12' are formed in line symmetry, it is possible to prevent excessive adhesive from being biased into the concave portion. That is, it becomes possible to evenly distribute excess adhesive. By uniformly distributing the excess adhesive, the thickness of the substrate assembly 14 after bonding the substrates can be made nearly uniform, leading to an improvement in manufacturing accuracy.

FIG. 5(a) is a diagram showing a configuration in which the recesses 12 and 12' are formed beyond the center position (center line) of the region 17. FIG. FIG. 5(b) is a modification of FIG. 5(a). By forming the concave portion 12 and the concave portion 12' as shown in FIG. There is a portion that partially overlaps with the recessed portion 12'. As a result, even if excess adhesive flows in the Y-axis direction when the first substrate 1 and the second substrate 2 are joined together, the two recesses 12 and 12′ overlap each other, resulting in a Y-axis. It is possible to suppress the flow of the adhesive in the axial direction.

FIG. 6(a) is a diagram showing a configuration in which the concave portion 12 is tapered. That is, the width of the concave portion becomes smaller as the distance from the channel increases. FIG. 6(b) is a modification of FIG. 6(a). By forming the concave portion 12 with such a shape, it is possible to facilitate the movement of excess adhesive due to joining to the tip side of the concave portion 12 by capillary action. As a result, the excess adhesive can be accommodated at a position farther away from the flow channel, and the overflow of the adhesive into the flow channel can be further suppressed.

(Example 1)
An energy generating element 5 made of TaSiN used for ejecting droplets, 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. is prepared. A silicon substrate was used as the substrate, and was thinned to a thickness of 625 μm by a grinder.

The first substrate 1 is formed with a through hole serving as the first flow path 8a, a through hole serving as the second flow path 8b, and a concave portion 12. As shown in FIG. The dimensions of the through-holes are rectangles of 150 μm×20 mm, and the distance between the through-holes is 100 μm. The dimensions of the recesses were 10 μm×40 μm, and the distance between the recesses was 20 μm. Using this patterned positive resist as a mask, the Bosch process is used to form the half shape of the first flow path 8a. Etching was performed for a predetermined time so that the depth of the first flow path 8a was 450 μm. At this time, the maximum depth from the joint surface was 315 μm.

Next, in the same manner as when the half-shape of the first flow path 8a was formed, a recess 12 was formed by forming a hole of 50 μm in the surface side of the first substrate. A second substrate having channels corresponding to the first substrate 1 was prepared. 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 formed on the transfer base material was brought into contact with the joint surface of the first substrate 1 while applying heat, thereby transferring the adhesive to the first substrate 1 .

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 forming the dry film, exposure and PEB were performed to form a latent image in order to form the flow path formed on the substrate assembly 14 . 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 8a first channel 8b second channel 12 recess 14 substrate assembly

Claims (10)

a first substrate having a first channel and a second channel formed adjacent to the first channel;
a second substrate bonded to the first substrate via an adhesive;
In a substrate assembly having
The first substrate further has a recess communicating with the first channel,
When viewed in a direction orthogonal to the first substrate, the recess is located between the first flow channel and the second flow channel to allow the flow from the first flow channel to the second flow channel. formed towards the road,
A substrate assembly, wherein the recess contains the adhesive. 2. The substrate assembly according to claim 1, wherein said recess communicates only with said first channel. 2. The substrate assembly according to claim 1, wherein said recess communicates with said first channel and said second channel. 4. The depth of the recess from the main surface of the first substrate is 0.5 to 0.9 times the thickness of the first substrate, according to any one of claims 1 to 3. substrate assembly. the second substrate further has a second recess communicating with the second flow path,
When viewed in a direction perpendicular to the first substrate, the second recess extends from the second channel to the second channel in the region between the first channel and the second channel. 1 is formed toward the flow path,
5. The substrate assembly according to any one of claims 1 to 4, wherein said adhesive is accommodated in said second recess. 6. The substrate according to claim 5, wherein the recess and the second recess are formed symmetrically with respect to a center line of a region between the first flow channel and the second flow channel. zygote. 7. The substrate according to claim 5 or 6, wherein said first recess and said second recess are formed over a center line of a region between said first channel and said second channel. zygote. 8. The substrate assembly according to any one of claims 1 to 7, wherein the width of said recess decreases toward said second flow path. 9. The substrate assembly according to any one of claims 1 to 8, wherein the width of said second recess decreases toward said first flow path. an ejection port for ejecting liquid;
a substrate assembly according to any one of claims 1 to 9;
In a liquid ejection head having
the first flow path is a supply flow path that supplies liquid to the ejection port;
The liquid discharge head, wherein the second flow path is a recovery flow path for collecting liquid that has not been discharged from the discharge port.

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