Flex Cable Slit Cover Layer for High-Temperature Delamination
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Solution Overview
Problem
Flexible printed wiring cables face delamination issues due to high temperature conditions during manufacturing and operation, limiting their application in high-temperature environments and requiring restrictive bending radii to prevent buckling and compressive stress.
Innovation Solution
Incorporating slits in the inner cover layer of the flex cable, which are filled with flexible filler material during lamination, reduces compressive stress and allows the cable to bend into desired curves without delamination, even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flex cable is subjected to high temperature conditions during manufacturing or operation, then the cable structure remains intact, but the cover layer delaminates and separates from the rest of the cable
Solution Approach 1:
The inner cover layer is segmented by forming slits that divide it into multiple sections. This segmentation allows the cover layer to accommodate thermal expansion and compression stresses during high-temperature conditions without delaminating, while maintaining overall structural integrity
Solution Approach 2:
The physical structure of the inner cover layer is changed by introducing slits, which modify its mechanical properties. The slits allow the material to expand and contract freely during temperature variations, preventing the build-up of compressive stress that would otherwise cause delamination
2Volume of moving object
If the radius of curvature of the flex cable is reduced to allow tighter bends, then the cable fits into smaller spaces, but the compressive stress in the cover layer increases and causes buckling
Solution Approach 1:
The inner cover layer is divided into segments by slits, which allows each segment to independently accommodate compression during bending. This prevents the accumulation of compressive stress that would otherwise cause buckling, enabling tighter bend radii
Solution Approach 2:
The slits introduce a new dimensional feature (through-thickness openings) that provides relief for in-plane compressive stresses during bending. This allows the cable to achieve tighter bends by managing stress in the thickness dimension rather than relying solely on large bend radii
3Reliability
If slits are formed in the inner cover layer to reduce compressive stress, then the cable can withstand high temperatures and tight bends, but the cover layer material is reduced which may expose internal components
Solution Approach 1:
A filler material is introduced as an intermediary substance that fills the slits in the inner cover layer. This filler material protects the exposed internal components from environmental hazards while allowing the slits to maintain their stress-relief function during high-temperature and bending conditions
Data Source
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AI summary
The present invention relates to flex cables, and more particularly to a temperature tolerant cover layer construction for a flex cable. In one embodiment, a flex cable designed to be bent to a particular curved shape includes one or more slits formed in the inner cover layer, to reduce the amount of material in the cover layer on the inside radius of the curve. By reducing the amount of cover layer material on the inside of the curve, the slits reduce the compressive stress in the cover layer. The slits are formed prior to laminating the flex cable so that upon lamination the flexible filler material below the cover layer fills the slits, providing a compliant, protective layer that bends into the desired curve and protects the active components inside the cable. The slits reduce the compressive stress along the inside cover layer and thereby prevent the cover layer from separating from the rest of the cable when the flex cable is subjected to high temperature conditions.