Flexible Printed Circuit Layering for Corrosion-Resistant Bending
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Solution Overview
Problem
Flexible printed circuits (FPCs) used in display devices tend to bounce, warp, and tear when bent, and their connection regions are prone to corrosion and structural failures due to inadequate protection and design.
Innovation Solution
A flexible printed circuit design with a substrate, conductive layers, and protective layers that include partial coverage and strategic openings to enhance flexibility, reduce bounce, and protect conductive layers from corrosion, featuring a layered structure with specific overlapping and uncovered regions to manage stress and improve bending performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the FPC structure is made more protective and robust, then reliability is improved, but flexibility and bending performance deteriorate
Solution Approach 1:
The patent applies different protective measures to different regions of the FPC. The connection region receives partial coverage from the first protective layer and additional coverage from the second protective layer, while the body region has different protective configurations. This localized approach provides enhanced protection where needed (connection regions prone to corrosion) while maintaining flexibility in other areas.
Solution Approach 2:
The protective system is divided into multiple layers: a first protective layer extending from the body region to the connection region, and a second protective layer covering additional areas including parts of the connection region and first bonding region. This segmentation allows each layer to be optimized for specific functions - the first layer provides basic protection and flexibility, while the second layer adds enhanced protection to critical areas.
2Reliability
If multiple protective layers are added to protect conductive layers, then corrosion resistance is improved, but the number of film layers increases causing more stress concentrations
Solution Approach 1:
Instead of uniformly adding protective layers across the entire FPC, the patent applies protective layers locally to specific regions. The first protective layer covers the connection region partially, and the second protective layer covers additional areas including parts of the connection region and first bonding region. This localized approach provides corrosion protection where conductive layers are most vulnerable while minimizing the total number of layers and associated stress concentrations.
3Reliability
If the FPC is designed with full coverage protective layers, then protection is improved, but flexibility and bending performance deteriorate
Solution Approach 1:
The patent implements partial coverage rather than full coverage. The first protective layer extends from the body region to the connection region but does not cover the entire connection region. The second protective layer covers additional areas including parts of the connection region and first bonding region. This partial coverage strategy provides necessary protection while leaving certain areas more flexible for bending operations.
Solution Approach 2:
The protective coverage is segmented into multiple non-contiguous regions. The first protective layer covers a first region including the connection region, while the second protective layer covers a second region including parts of the connection region and first bonding region. This segmentation allows flexibility to be maintained in areas not covered by protective layers while providing protection where required.
Data Source
AI summary
A flexible printed circuit includes a substrate, a first conductive layer, and a first protective layer. The substrate has a body region, a first bonding region, and a connection region located between the body region and the first bonding region. The first conductive layer is located on a first side of the substrate, and extends from the body region to the first bonding region via the connection region. The first protective layer is located on a side of the first conductive layer away from the substrate, and extends from the body region to the connection region. The first protective layer partially covers the connection region.