Flexible Circuit Board Edge Reinforcement for Crack Resistance
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Solution Overview
Problem
Circuit boards with flexible parts tend to develop cracks, leading to potential disconnection of conductive wires when bent, due to stress concentration and material failure.
Innovation Solution
Incorporating non-conductive metal patterns closer to the outer edges of the flexible parts, which act as dummy patterns and reduce stress concentration, thereby suppressing crack formation and preventing conductive wire disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexible parts are made thinner to increase flexibility, then ease of bending is improved, but crack resistance deteriorates
Solution Approach 1:
The patent applies different properties to different regions of the flexible part by adding non-conductive metal patterns specifically at the outer edge, while keeping the inner region (where conductive wires are located) free of such patterns. This local differentiation allows the outer edge to have enhanced crack resistance without compromising the overall flexibility needed for bending operations.
Solution Approach 2:
The patent converts the harmful stress concentration that normally occurs at the outer edge during bending into a beneficial effect by strategically placing non-conductive metal patterns at these high-stress locations. These patterns act as stress distributors that prevent crack initiation and propagation, thereby transforming the vulnerable outer edge into a protected region that enhances overall durability.
2Ease of operation
If flexible parts are made thinner to improve flexibility, then ease of bending is improved, but reliability deteriorates due to wire disconnection
Solution Approach 1:
The non-conductive metal patterns serve as an intermediary protective layer between the external bending stresses and the conductive wires. By positioning these patterns at the outer edge (closer to the bending surface), they act as a first line of defense that absorbs and distributes stress before it can reach the conductive wires located at the inner edge, thereby protecting the electrical connections from disconnection.
3Strength
If non-conductive metal patterns are added to flexible parts, then crack resistance is improved, but device complexity increases
Solution Approach 1:
Instead of uniformly adding protective structures throughout the flexible part, the patent applies non-conductive metal patterns only at the outer edge where cracks most frequently initiate. This localized approach provides maximum crack resistance with minimal additional complexity, as the protective feature is confined to the specific region where it is most needed rather than being applied universally.
4Strength
If non-conductive metal patterns are placed closer to the outer edge, then crack suppression is improved, but manufacturing precision requirements increase
Solution Approach 1:
The non-conductive metal patterns are formed using standard PCB manufacturing techniques (such as screen printing or photolithography of non-conductive ink) that are already widely available in the industry. By utilizing existing, cost-effective manufacturing processes rather than requiring new precision technologies, the patent achieves the desired pattern placement without significantly increasing manufacturing complexity or cost.
Data Source
AI summary
A circuit board (3) is provided with a first rigid part (11) having a power system electronic component mounted thereon, a second rigid part (12) having a control system electronic component mounted thereon, and a thin flexible part (13) connecting the first and second rigid parts to each other. The flexible part (13) is provided with a plurality of conductive wires (27) conducted with the electronic components of the first and second rigid parts (11, 12). A non-conductive metal pattern (33) that is a dummy pattern is formed along an outer edge (13a) of the flexible part (13). By the non-conductive metal pattern (33), the disconnection of the conductive wires (27) due to cracking is suppressed.