Liquid Ejection Head Adhesive System for Thermal Stress Relief
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Solution Overview
Problem
Existing liquid ejection heads face reliability issues due to temperature changes, which can cause stress and potential breakage of wiring in the wiring board, especially when different materials with varying linear expansion coefficients are used.
Innovation Solution
The liquid ejection head employs a multi-adhesive agent system where the wiring board is adhered to the support member and channel member using different adhesive agents with specific Young's moduli, ensuring that the support member is adhered to the channel member with a third adhesive agent having a lower Young's modulus than the first adhesive agent, and the second adhesive agent has a lower Young's modulus than the first and third adhesive agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wiring board is adhered to members with different linear expansion coefficients using a single adhesive agent, then the structure is simple, but stress is applied to the wiring board during temperature changes causing wiring breakage
Solution Approach 1:
The adhesive system is segmented into multiple adhesive agents with different Young's moduli positioned at different locations. The first adhesive agent with higher Young's modulus provides strong bonding where structural support is needed, while the second adhesive agent with lower Young's modulus is positioned to reduce stress on the wiring board during thermal expansion, preventing wiring breakage.
Solution Approach 2:
Different adhesive agents with specific Young's moduli are applied at different locations on the wiring board. The first adhesive agent (higher Young's modulus) is used where strong adhesion is required, while the second adhesive agent (lower Young's modulus) is used in regions where stress reduction is critical for preventing wiring breakage during temperature changes.
2Reliability
If looseness is provided in the wiring board to reduce tension, then wiring breakage is reduced, but control of adhesive agent amount, thickness, and width becomes difficult
Solution Approach 1:
The Young's modulus parameter of the adhesive agents is changed to solve the problem. By selecting adhesive agents with specific Young's modulus values (first adhesive agent with higher modulus, second with lower modulus), the patent achieves both reliable bonding and stress reduction without requiring loose wiring board construction, thereby maintaining manufacturing precision for adhesive amount, thickness, and width.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the reliability of the liquid ejection head against temperature changes by reducing stress on the wiring board, thereby minimizing the risk of wiring breakage.
Implementation Method 1
the wiring board is adhered to the support member by a first adhesive agent, and is adhered to the channel member by a second adhesive agent, the support member is adhered to the channel member by a third adhesive agent whose Young's modulus after curing is lower than the Young's modulus of the first adhesive agent after curing
Implementation Method 2
The members and the wiring board are made of different materials in many cases, and the linear expansion coefficients thereof vary in some cases. Assume a case where the linear expansion coefficients of the wiring board and the members vary. If the wiring board is attempted to be joined to the members with tension applied to the wiring board, a temperature change causes stress to be applied to the wiring board
Implementation Method 3
the support member is adhered to the channel member by a third adhesive agent whose Young's modulus after curing is lower than the Young's modulus of the first adhesive agent after curing
Data Source
AI summary
Provided are a liquid ejection head with high reliability against a temperature change and a manufacturing method of the same. To this end, a wiring board is adhered to a support member by a first adhesive agent, and is adhered to a channel member by a second adhesive agent whose Young's modulus after curing is lower than that of the first adhesive agent. The support member is adhered to the channel member by a third adhesive agent whose Young's modulus after curing is lower than that of the first adhesive agent, and the Young's modulus of the second adhesive agent after curing is lower than those of the first adhesive agent and the third adhesive agent.