Rip Stop Transition Layer for Flexible Circuit Boards
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Solution Overview
Problem
Wearable electronic devices face reliability challenges due to mechanical stress and strain on components, circuit boards, and interconnects as they are designed to bend, flex, and stretch, leading to potential ripping and cracking of flexible circuit boards and copper conductors.
Innovation Solution
A rip stop material with an open weave interlocking fabric is attached to high stress areas of flexible circuit boards to form a transition layer, minimizing cracking and ripping by distributing stress and providing reinforcement, which can be laminated on top of coverlays or integrated within the circuit board layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the flexible circuit board is made more flexible to allow bending and flexing, then the wearability and adaptability are improved, but the mechanical strength and reliability deteriorate, leading to ripping and cracking
Solution Approach 1:
The patent applies different materials and structures to different regions of the flexible circuit board. Specifically, it uses a multi-layer construction where certain layers provide flexibility while others provide strength, and places support structures at specific high-stress locations rather than uniformly across the entire board.
Solution Approach 2:
The patent employs composite material structures combining multiple layers including flexible substrates, rigid support layers, adhesive layers, and reinforcement materials. This composite approach allows the circuit board to simultaneously achieve flexibility for wearability and structural strength to prevent ripping and cracking.
2Strength
If the flexible circuit board is reinforced to prevent ripping and cracking, then the mechanical strength is improved, but the flexibility and wearability deteriorate
Solution Approach 1:
The patent places reinforcement structures selectively at high-stress areas such as bend zones and connection points rather than making the entire board rigid. This localized reinforcement maintains overall flexibility while providing strength where needed most.
Solution Approach 2:
The patent divides the circuit board into multiple functional layers and segments, allowing different regions to have different properties. The segmented structure enables some parts to be more flexible while others provide reinforcement, resolving the contradiction between overall flexibility and localized strength.
3Ease of manufacture
If the circuit board structure is simplified to reduce manufacturing complexity, then the ease of manufacture is improved, but the ability to withstand mechanical stress deteriorates
Solution Approach 1:
The patent incorporates support structures and reinforcement layers during the initial manufacturing process rather than adding them later. This preliminary integration ensures proper alignment and bonding while maintaining manufacturing efficiency, avoiding complex post-processing steps.
Solution Approach 2:
The patent uses composite material layers that can be manufactured using standard flexible circuit board fabrication processes. The multi-layer structure is built up sequentially using conventional lamination and etching techniques, maintaining ease of manufacture while achieving enhanced stress resistance.
Data Source
AI summary
A rip stop material is attached at a stress area of a flexible circuit board in order to strengthen the flexible circuit board and minimize ripping and cracking in the polyimide and/or the copper conductors of the circuit. A rip stop transition layer is formed and deposited at a location on the flexible circuit in order to minimize, reduce, if not preventing cracking and ripping of the circuit as it is bent and flexed. The rip stop transition layer can be placed at different locations on and within the flexible circuit in order to minimize cracking and ripping as the flexible circuit is bent, flexed and twisted.