Liquid Ejection Head Cover Member Adhesion Design
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Solution Overview
Problem
Conventional liquid ejection heads face issues with interface delamination between the substrate and cover member due to thin cover members, leading to reduced adhesion and potential ink color mixing, especially when multiple flow paths communicate with each other.
Innovation Solution
A liquid ejection head design featuring a cover member with partitioning members and slits that allow for improved adhesion between the substrate and adhesive member, reducing the likelihood of interface delamination and ink color mixing by creating a cover member opening for the adhesive to contact the substrate, thereby enhancing the structural integrity and preventing flow path communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the cover member is made thin to reduce flow resistance at communication holes, then the flow resistance is reduced, but the adhesion between substrate and cover member is lowered
Solution Approach 1:
The cover member is segmented into a thin film portion (for low flow resistance) and a protruding portion extending toward the adhesive member (for enhanced adhesion). This segmentation allows each region to fulfill its specific function optimally.
Solution Approach 2:
The adhesion enhancement is achieved by extending the cover member in the thickness dimension (z-direction) to form a protruding portion that reaches the adhesive member, adding a vertical dimension to the adhesion interface without increasing the planar area.
2Reliability
If the adhesive member layer thickness is increased to improve adhesion, then the adhesion is improved, but the substrate thickness increases and placement precision is lowered
Solution Approach 1:
The protruding portion of the cover member is designed in advance to extend into the adhesive member layer, providing a mechanical interlocking structure that compensates for adhesive layer thickness variations and prevents delamination without requiring excessive adhesive thickness.
3Loss of energy
If the cover member is made thin to reduce flow resistance, then the flow resistance is reduced, but physical stress and deflection increase causing interface delamination
Solution Approach 1:
The cover member is divided into a thin film region (for low flow resistance) and a reinforced protruding portion (for stress resistance). The protruding portion acts as a structural reinforcement that withstands physical stress and deflection forces.
Solution Approach 2:
The cover member structure combines a thin film material (for low flow resistance) with a protruding reinforcement structure (for mechanical strength), creating a composite structure that exhibits both low flow resistance and high stress resistance.
Data Source
AI summary
A liquid ejection head includes a recording element substrate having a substrate provided with a plurality of flow paths for liquid to be ejected on a recording material by a recording element and a cover member that is provided with a plurality of communication holes in communication with the plurality of flow paths and that is joined to the substrate, a liquid supply member supplying the liquid to the plurality of flow paths through the plurality of communication holes of the cover member, and an adhesive member adhering the cover member and the liquid supply member. At least a part of an abutment region of the cover member in abutment against the substrate and apart from a region provided with the plurality of communication holes has a cover member opening for contacting the adhesive member and the substrate to each other.