Uneven Adhesive Sheet Structure for Lower Pickup Force
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Solution Overview
Problem
Existing pressure sensitive adhesive sheets often require excessive force to release objects, particularly fragile items like semiconductor elements, risking breakage during removal.
Innovation Solution
The adhesive sheet features a pressure sensitive adhesion layer with unevenness, characterized by a concave portion and convex portions, adhering to a specific thickness ratio (0.25<S/H<4.75), which reduces the pickup force required for object release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a pressure sensitive adhesive sheet uses a uniform thickness adhesive layer, then the adhesive strength is high, but the release force becomes excessive causing damage to fragile objects
Solution Approach 1:
The adhesive layer is designed with non-uniform thickness, creating local variations where convex portions provide stronger adhesion and concave portions provide weaker adhesion. This local quality variation allows the adhesive sheet to maintain overall adhesive strength while creating specific release points that reduce force on fragile objects during removal
2Strength
If the adhesive layer thickness is increased, then the adhesive strength increases, but the pickup force required for release increases excessively
Solution Approach 1:
By creating local thickness variations with convex portions (higher thickness) and concave portions (lower thickness), the adhesive sheet achieves regions of different adhesive strength. The concave portions act as stress relief zones that reduce the overall pickup force required for release while the convex portions maintain sufficient adhesive strength for secure bonding
3Reliability
If a groove is provided on the adhesive layer surface to remove air bubbles, then bonding quality improves, but the adhesive strength is reduced
Solution Approach 1:
The invention creates local thickness variations that serve dual functions: the convex portions maintain adhesive strength while the concave portions naturally trap and manage air bubbles during bonding. This approach improves bonding quality through better air bubble management while preserving adhesive strength through the convex portion structure
Solution Approach 2:
Instead of modifying the surface topology with grooves (2D surface feature), the invention modifies the thickness dimension (3D volume feature) of the adhesive layer. This dimensional approach allows air bubble management and adhesive strength optimization to occur simultaneously within the volume of the adhesive layer rather than competing at the surface level
Data Source
AI summary
A pressure sensitive adhesive sheet includes a base material and a pressure sensitive adhesion layer having unevenness on the layer surface. The pressure sensitive adhesion layer includes an underlying base constituted by a part from a concave portion where, in the thickness direction of the pressure sensitive adhesion layer, a thickness of the pressure sensitive adhesion layer is smallest, to a face on the opposite side of the surface with the unevenness, and a convex portion provided on the underlying base. The pressure sensitive adhesion layer satisfies Relational Expression (1) given below.0.25<S/H<4.75Relational Expression (1)(In Relational Expression (1), S represents a thickness of the underlying base, and H represents a height of the convex portion.)