Liquid Ejection Head Adhesive Protrusion Control
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Solution Overview
Problem
In liquid ejection heads, such as inkjet print heads, the adhesive used to join substrates can protrude and affect ejection characteristics by overlapping vibration plates or clogging supply ports, leading to changes in vibration characteristics and obstructed liquid supply.
Innovation Solution
The liquid ejection head is designed with specific curvature radii for the corners of openings in the substrates, controlling the flow and protrusion of the adhesive relative to the structure at joined surfaces, thereby minimizing interference with the vibration film and supply ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If substrates are joined together with adhesive, then the substrates are securely connected, but the adhesive may protrude and affect ejection characteristics
Solution Approach 1:
The patent applies different curvature radius values to different locations of the opening corners. Specifically, first corners have a curvature radius of 5-15 μm while second corners have a curvature radius of 20-30 μm. This local differentiation controls adhesive flow patterns at specific locations, preventing protrusion into critical areas while maintaining secure substrate connection.
Solution Approach 2:
The patent utilizes curved corners with specific radius values instead of sharp or flat corners. The opening corners are designed with controlled curvature radii (5-15 μm for first corners, 20-30 μm for second corners) to manage adhesive flow and prevent protrusion. The curved geometry directs adhesive away from sensitive regions like the vibration plate and supply ports.
2Strength
If adhesive is applied between substrates, then the substrates are joined, but the adhesive may clog supply ports and obstruct liquid supply
Solution Approach 1:
Different curvature radii are assigned to corners based on their proximity to supply ports. Corners closer to supply ports have larger curvature radii (20-30 μm) that prevent adhesive intrusion, while other corners have smaller radii (5-15 μm). This localized differentiation ensures supply port clearance while maintaining bonding strength.
Solution Approach 2:
The opening corners are pre-formed with specific curvature radii before adhesive application. This preliminary geometric configuration guides adhesive flow during the bonding process, proactively preventing clogging of supply ports before the adhesive can obstruct liquid supply pathways.
3Strength
If adhesive overlaps the vibration plate, then the substrates are joined, but the vibration characteristics change
Solution Approach 1:
The patent differentiates corner curvature radii based on their relationship to the vibration plate location. First corners with smaller radii (5-15 μm) are positioned away from the vibration plate, while second corners with larger radii (20-30 μm) provide a buffer zone. This localized geometric control prevents adhesive from reaching the vibration plate, preserving its vibration characteristics while maintaining assembly integrity.
Data Source
AI summary
A liquid ejection head includes a first substrate having a first surface and a second surface opposite the first surface, the first surface having a structure, a second substrate having a second surface facing the first surface of the first substrate, and a third substrate having a first surface facing the second surface of the first substrate. The first, second, and third substrates are joined together by an adhesive. The second surface of the first substrate has an opening located in a region on a rear side of the structure and having corners each having a curvature radius R2. The second surface of the second substrate has an opening in a region facing the structure and having corners each having a curvature radius R1. The curvature radii R1 and R2 satisfy R1<R2.