Printed Circuit Board Cutout for Flexible Wiring Stress Reduction
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Solution Overview
Problem
The stress at connection terminals between flexible wiring substrates and display panels or printed circuit boards in curved electronic devices leads to reliability issues, such as electrical connection failures and peeling off of substrates, due to the rigidity of the printed circuit board and the curvature of the display panel.
Innovation Solution
A structure with a printed circuit board featuring a cutout, such as a V-shaped or semicircle-shaped cutout, between flexible wiring substrates to reduce stress at connection terminals, allowing for flexible deformation and maintaining high reliability of connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the printed circuit board is made flat and rigid to install electronic components, then the ease of manufacture is improved, but the stress at connection terminals increases causing reliability issues
Solution Approach 1:
The printed circuit board is divided into multiple regions with different structural characteristics: a first region with normal thickness for component mounting, and a second region with reduced thickness at connection terminals. This segmentation allows each region to optimize its function while reducing overall stress concentration.
Solution Approach 2:
The printed circuit board exhibits non-uniform thickness distribution, with the second region having smaller thickness than the first region. This local quality variation reduces flexibility and stress at connection terminals specifically, while maintaining the overall rigidity needed for component installation.
2Adaptability or versatility
If the display panel is curved to meet design needs, then the adaptability is improved, but the stress at connection portions increases causing peeling and electrical failures
Solution Approach 1:
The connection portions of the printed circuit board are designed with locally reduced thickness to decrease flexibility specifically at these critical areas. This local modification reduces stress concentration during curving while maintaining the overall adaptability of the display panel to achieve desired curved shapes.
Solution Approach 2:
The printed circuit board is segmented into functional regions with different thickness characteristics, allowing the connection portions to have different mechanical properties than the main body. This enables the board to accommodate curving requirements while protecting connection terminals from excessive stress.
3Volume of moving object
If the printed circuit board is folded to the back of the display panel to minimize device dimensions, then the volume is reduced, but the stress at connection terminals becomes very big causing reliability problems
Solution Approach 1:
The printed circuit board is designed with non-uniform thickness where connection terminals have reduced thickness compared to the main body. This local quality difference reduces the stress concentration at connection portions during folding, enabling compact device configuration while maintaining connection reliability.
4Adaptability or versatility
If the flexible wiring substrate connects curved display panel to flat printed circuit board, then the adaptability is improved, but the stress at connection terminals increases due to rigidity mismatch
Solution Approach 1:
The printed circuit board connection portions have locally reduced thickness to decrease flexibility and reduce stress concentration. This creates a better mechanical match with the flexible wiring substrate at connection points, reducing stress transfer while maintaining the adaptability needed to connect curved and flat components.
Data Source
AI summary
An electronic device comprising: a substrate having a curved surface, a printed circuit board, and plural flexible wiring substrates, each of two of the plural flexible substrates has a terminal portion that is connected to the curved surface, the printed circuit board has a cutout between the two flexible wiring substrates.