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US-20260124832-A1 - SUBSTRATE JOINING METHOD, SUBSTRATE ASSEMBLY, AND INKJET PRINT HEAD

US20260124832A1US 20260124832 A1US20260124832 A1US 20260124832A1US-20260124832-A1

Abstract

A joining method includes the steps of applying a first adhesive in a line shape to a joining area of a first substrate, applying a second adhesive in a broken line shape to the joining area of the first substrate, at a predetermined interval from the first adhesive layer in the line shape, to form multiple second adhesive layers with a gap formed due to the broken line shape, bonding the second substrate to the first substrate with the first adhesive layer and the multiple second adhesive layers and pressure-bonding the second substrate to the first substrate, curing the multiple second adhesive layers between the first substrate and the second substrate pressure-bonded, and curing the first adhesive layer after the multiple second adhesive layers are cured.

Inventors

  • Yu KATANO

Assignees

  • CANON KABUSHIKI KAISHA

Dates

Publication Date
20260507
Application Date
20251029
Priority Date
20241107

Claims (16)

  1. 1 . A joining method comprising the steps of: applying a first adhesive in a line shape to a joining area of a first substrate to form a first adhesive layer; applying a second adhesive in a broken line shape to the joining area of the first substrate, at a predetermined interval from the first adhesive layer in the line shape, to form a plurality of second adhesive layers with a gap formed due to the broken line shape; bonding a second substrate to the first substrate with the first adhesive layer and the plurality of second adhesive layers and pressure-bonding the second substrate to the first substrate; curing the plurality of second adhesive layers between the first substrate and the second substrate pressure-bonded; and curing the first adhesive layer after the plurality of second adhesive layers are cured.
  2. 2 . The joining method according to claim 1 , wherein a length of each of the plurality of second adhesive layers is longer than a length of the gap.
  3. 3 . The joining method according to claim 1 , wherein the plurality of second adhesive layers are arranged along two opposite sides in an outer periphery of the joining area.
  4. 4 . The joining method according to claim 1 , wherein the first substrate is a semiconductor substrate, and the second substrate is a metal substrate.
  5. 5 . The joining method according to claim 1 , wherein the second substrate has an opening, and an inner periphery of the joining area corresponds to an outer periphery of the opening.
  6. 6 . The joining method according to claim 1 , wherein a length of the plurality of second adhesive layers is equal to or longer than two-thirds of a length of a side of the first substrate adjacent to the plurality of second adhesive layers.
  7. 7 . The joining method according to claim 1 , wherein the first adhesive layer is formed of a thermosetting adhesive.
  8. 8 . The joining method according to claim 7 , wherein the plurality of second adhesive layers are formed of a material that cures at a lower temperature than the first adhesive layer.
  9. 9 . An assembly comprising: a first substrate and a second substrate joined together; a first adhesive layer formed of a first adhesive in a line shape between the first substrate and the second substrate; and a plurality of second adhesive layers formed of a second adhesive in a broken line shape and arranged adjacent to the first adhesive layer in the line shape, the plurality of second adhesive layers having a gap due to the broken line shape.
  10. 10 . An inkjet print head comprising: a first substrate and a second substrate joined together; a first adhesive layer formed of a first adhesive in a line shape between the first substrate and the second substrate; a plurality of second adhesive layers formed of a second adhesive in a broken line shape and arranged adjacent to the first adhesive layer in the line shape, the plurality of second adhesive layers having a gap due to the broken line shape; and an ejection chip mounted on the first substrate, covered with the second substrate, and having an ejection nozzle, the ejection nozzle surrounded by an opening of the second substrate, and exposed from the opening.
  11. 11 . The inkjet print head according to claim 10 , wherein a length of the plurality of second adhesive layers is longer than a length of the gap.
  12. 12 . The inkjet print head according to claim 10 , wherein the plurality of second adhesive layers are formed of a material that cures at a lower temperature than the first adhesive layer.
  13. 13 . The inkjet print head according to claim 10 , wherein the plurality of second adhesive layers are arranged along two opposite sides of the first substrate.
  14. 14 . The inkjet print head according to claim 10 , wherein the first substrate is a semiconductor substrate, and the second substrate is a metal substrate.
  15. 15 . The inkjet print head according to claim 10 , wherein a length of the plurality of second adhesive layers is equal to or longer than two-thirds of a length of a side of the first substrate adjacent to the plurality of second adhesive layers.
  16. 16 . The inkjet print head according to claim 10 , wherein the first adhesive layer is formed of a thermosetting adhesive.

Description

BACKGROUND Field of the Technology The present disclosure relates to a substrate joining method, a substrate assembly, and an inkjet print head, and more specifically relates to a technique for bonding substrates together by using temporary fixing with a thermosetting adhesive. Description of the Related Art Japanese Patent Laid-Open No. 2010-82537 (hereinafter referred to as Patent Literature 1) describes a technique for bonding substrates together by using a main adhesive which is thermosetting and has a relatively high adhesive strength and a temporary adhesive which is also thermosetting. In Patent Literature 1, the temporary adhesive is spot-applied to the joining surfaces of the substrates and is cured to temporarily bond the substrates together in a step before the main adhesive is cured. However, in a case where the spot application is used to bond a substrate with low wettability, such as a semiconductor substrate for use in, for example, an inkjet head, to another substrate, it is difficult to control an amount of the adhesive applied, resulting in an unstable amount of the adhesive applied. In addition, even though the adhesive is applied, it is difficult to obtain a desired adhesive strength. In contrast, in a case where an adhesive is applied in a line shape, it is possible to stably control the amount of the adhesive applied, and therefore also to ensure the adhesive strength of the adhesive. However, in a case where a line-shaped main adhesive and the line-shaped temporary adhesive are applied close to each other, an air bubble may be trapped between the two adhesives. Then, in the process of thermally curing the main adhesive, this trapped air bubble expands and generates a leak path passing through the main adhesive, which may cause defects in products manufactured by using the bonded substrates. SUMMARY The disclosure intends to provide a substrate joining method of bonding substrates together without generating a leak path, a substrate assembly, and an inkjet print head. The disclosure relates to a joining method including the steps of applying a first adhesive in a line shape to a joining area of a first substrate, applying a second adhesive in a broken line shape to a joining area of the first substrate, at a predetermined interval from the first adhesive layer in the line shape, to form multiple second adhesive layers with a gap formed due to the broken line shape, bonding a second substrate to the first substrate with the first adhesive layer and the plurality of second adhesive layers and pressure-bonding the second substrate to the first substrate, curing the multiple second adhesive layers between the first substrate and the second substrate pressure-bonded, and curing the first adhesive layer after the multiple second adhesive layers are cured. Features of the present disclosure will become apparent from the following description of embodiments with reference to the attached drawings. The following description of embodiments is described by way of example. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a top view illustrating a state where a temporary adhesive and a main adhesive are applied to a joining surface of a substrate to be joined according to a comparative example; FIG. 1B is a top view illustrating a state where the temporary adhesive and the main adhesive are applied to the joining surface of the substrate to be joined according to the comparative example; FIG. 1C is a top view illustrating a state where the temporary adhesive and the main adhesive are applied to the joining surface of the substrate to be joined according to the comparative example; FIG. 1D is a top view illustrating a state where the temporary adhesive and the main adhesive are applied to the joining surface of the substrate to be joined according to the comparative example; FIG. 1E is a top view illustrating a state where the temporary adhesive and the main adhesive are applied to the joining surface of the substrate to be joined according to the comparative example; FIG. 2A is a cross-sectional view taken alone a line A-A in FIG. 1A; FIG. 2B is a cross-sectional view taken alone a line A-A in FIG. 1B; FIG. 2C is a cross-sectional view taken alone a line A-A in FIG. 1C; FIG. 2D is a cross-sectional view taken alone a line A-A in FIG. 1D; FIG. 2E is a cross-sectional view taken alone a line A-A in FIG. 1E; FIGS. 3A and 3B are plan views illustrating two substrates to be joined and joining areas according to an embodiment; FIG. 4 is a flowchart presenting processing of bonding a first substrate and a second substrate together according to the embodiment; FIG. 5A is a view for explaining application of a main adhesive to a first subtract in step 401 in FIG. 4; FIG. 5B is an enlarged view illustrating a part of the first substrate illustrated in FIG. 5A; FIG. 6A is a view for explaining application of a temporary adhesive to the first substrate in step 402 in FIG. 4; FIG. 6B is an enlarged view illustratin