Resin Substrate Tapered Protrusions Moisture Infiltration
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Solution Overview
Problem
Conventional resin substrates face issues with moisture infiltration between the resist film and coverlay film, leading to corrosion of conductor patterns and changes in electrical characteristics, due to the lack of patterning accuracy and flexibility.
Innovation Solution
A resin substrate design featuring a resist film with protruding portions along its outer circumference, which are tapered in shape, allowing the coverlay film to be easily attached and preventing moisture infiltration by sandwiching exposed conductor pattern portions, thereby reducing corrosion and maintaining flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a stretchable coverlay film is attached to the surface of the resin base material to maintain flexibility, then the flexibility of the resin substrate is maintained, but the coverlay film is likely to be deformed or displaced resulting in low patterning accuracy
Solution Approach 1:
The patent uses a flexible coverlay film that can be stretched and deformed to match the contours of the underlying structure, allowing the film to conform to the resin base material while maintaining flexibility. This resolves the contradiction by enabling the film to adapt to shape changes without compromising its ability to provide precise coverage and protection.
2Manufacturing precision
If a resist film with high patterning accuracy is formed on the surface of the resin base material, then the patterning accuracy is improved, but the flexibility of the resin substrate is lowered
Solution Approach 1:
The patent employs a flexible resist film that can be stretched and deformed to match the underlying structure, allowing the film to provide high patterning accuracy while maintaining the flexibility of the resin substrate. This resolves the contradiction by enabling the resist film to conform to shape changes without compromising its patterning precision.
3Adaptability or versatility
If a part of the resist film is covered with the coverlay film to eliminate flexibility decrease, then the flexibility of the resin substrate is maintained, but minute gaps are likely to be formed along the boundary allowing external moisture to infiltrate
Solution Approach 1:
The patent introduces protruding portions with curved surfaces at the boundaries between the resist film and coverlay film. These curved surfaces enable the coverlay film to conform smoothly to the underlying structure, eliminating gaps and preventing moisture infiltration while maintaining the flexibility of the resin substrate. This resolves the contradiction by providing both flexibility and reliable moisture protection.
Data Source
AI summary
A resin substrate includes a resin base material including a first main surface, electrode pads provided on the first main surface, circuit conductor patterns, a resist film, and a coverlay film. The resist film includes, on the outer circumference, a plurality of protruding portions each of which has a tapered shape with a vertex. A portion of the circuit conductor patterns are covered with the resist film, and the coverlay film covers a portion of the resist film including the protruding portions and exposed portions of the circuit conductor patterns. The protruding portions are located at positions sandwiching the exposed portions of the circuit conductor patterns.