Pressure-Sensitive Adhesive Sheet With Metal Core For Magnetic Disk Drive
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Solution Overview
Problem
Pressure-sensitive adhesive sheets used in magnetic disk drives often develop wrinkles when attached, compromising the air tightness and allowing foreign substances like moisture and siloxane compounds to enter the drive, necessitating frequent replacement.
Innovation Solution
A pressure-sensitive adhesive sheet with a base comprising a metal layer sandwiched between two plastic film layers, where the metal layer has a thickness of 2 μm to 15 μm and the total thickness of the plastic film layers is within 25 μm to 70 μm, with a thickness ratio of 1.5 to 7.0, reducing wrinkle formation and enhancing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure-sensitive adhesive sheet is attached to seal the gap between the base member and cover, then air tightness is improved, but wrinkles form on the adhesive sheet compromising the seal
Solution Approach 1:
The base is constructed as a composite material consisting of a metal layer sandwiched between two plastic film layers. This composite structure combines the rigidity and barrier properties of metal with the flexibility and adhesion properties of plastic films, enabling the adhesive sheet to maintain flatness while conforming to surfaces and forming reliable seals without wrinkles.
Solution Approach 2:
The thickness of the metal layer is controlled within a specific range (2-15 μm) and the total thickness of plastic film layers is optimized (25-70 μm). By precisely controlling these dimensional parameters, the base achieves an optimal balance between rigidity (to prevent wrinkles) and flexibility (to conform to surfaces), resolving the contradiction between maintaining flatness and adapting to uneven surfaces.
2Strength
If the metal layer thickness is increased to improve rigidity, then wrinkle formation is reduced, but the adhesive sheet becomes too rigid to conform to uneven surfaces
Solution Approach 1:
The composite structure of metal layer between plastic film layers creates a synergistic effect where the metal provides rigidity and the plastic films provide flexibility. This allows the adhesive sheet to simultaneously achieve sufficient rigidity to prevent wrinkles while maintaining the ability to conform to uneven surfaces through the flexible plastic film layers.
Solution Approach 2:
By optimizing the metal layer thickness to 2-15 μm (not too thin to lose rigidity, not too thick to become overly rigid) and controlling the total plastic film thickness to 25-70 μm, the adhesive sheet achieves the optimal balance between rigidity and flexibility, enabling it to conform to uneven surfaces without forming wrinkles.
3Adaptability or versatility
If the adhesive sheet is made thinner to improve conformability, then followability to uneven surfaces is improved, but the sheet loses rigidity and wrinkles form
Solution Approach 1:
The composite structure allows the adhesive sheet to be thin overall while maintaining rigidity through the metal layer. The plastic film layers provide the necessary flexibility for conformability, while the metal core prevents excessive bending that would cause wrinkles, enabling the sheet to be both thin and rigid simultaneously.
Solution Approach 2:
By controlling the metal layer thickness to at least 2 μm and the total plastic film thickness to 25-70 μm, the adhesive sheet achieves sufficient rigidity to prevent wrinkles while maintaining thin overall dimensions for good conformability to uneven surfaces.
4Ease of manufacture
If a single-layer adhesive sheet is used to simplify the structure, then manufacturing is easier, but the sheet develops wrinkles and fails to maintain air tightness
Solution Approach 1:
The composite structure of metal layer between plastic film layers is manufactured as an integrated base unit, combining multiple materials with complementary properties. This composite construction prevents wrinkle formation and maintains air tightness while being produced through established lamination and bonding processes, achieving reliability without excessive manufacturing complexity.
Data Source
AI summary
A pressure-sensitive adhesive sheet according to the present invention includes a base including a metal layer, a first plastic film layer A, and a second plastic film layer B and a pressure-sensitive adhesive layer on a surface of the second plastic film B. The metal layer is positioned between the first plastic film layer A and the second plastic film layer B. The metal layer has a thickness of 2 μm to 15 μm. A total of a thickness Ta of the first plastic film layer A and a thickness Tb of the second plastic film layer B is within a range of 25 μm to 70 μm.