Flexible Substrate Wiring Layout for Bending Stress Relief
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Solution Overview
Problem
Flexible substrates with electrical elements face damage from stress caused by bending or stretching, particularly in wiring lines, which existing measures like honeycomb-shaped openings and meandering wiring do not adequately address.
Innovation Solution
The flexible substrate design includes meandering scanning and signal lines covered by inorganic insulating films that cover their side edges, acting as stress relaxation layers, reducing strain and breakage risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wiring lines are made straight and continuous for simple structure, then ease of manufacture is improved, but reliability deteriorates due to stress concentration during bending and stretching
Solution Approach 1:
The inorganic insulating film is divided into multiple segments along the wiring line, with gaps between segments. This segmentation allows the film to flex and accommodate stress during bending and stretching, preventing crack propagation while maintaining electrical insulation where needed.
Solution Approach 2:
The inorganic insulating film is designed with dynamic characteristics through its segmented structure, allowing it to adapt its configuration during substrate deformation. The gaps enable the film to expand and contract dynamically, maintaining integrity under stress while providing insulation during normal operation.
2Reliability
If honeycomb-shaped openings are provided in the base to reduce stress, then reliability is improved, but device complexity increases
Solution Approach 1:
Instead of modifying the entire base structure with honeycomb openings, the inorganic insulating film is locally modified with gaps only at specific positions along the wiring lines. This localized approach reduces stress concentration where needed while maintaining the integrity and simplicity of the overall base structure.
3Reliability
If wiring is shaped in a meandering manner to reduce stress, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The inorganic insulating film is segmented into multiple sections with gaps between them. This segmentation allows the film to accommodate stress and deformation without requiring the wiring itself to follow complex meandering paths, thereby maintaining simpler wiring geometry while still achieving stress reduction and improved reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces strain and stress on wiring lines, minimizing the risk of breakage and enhancing the durability of flexible substrates under elongation.
Implementation Method 1
a first inorganic insulating film covering the scanning lines and a second inorganic insulating film covering the signal lines, and the first inorganic insulating film is formed into a strip shape which overlaps the first strip portions, the second inorganic insulating film is formed into a strip shape which overlaps the second strip portions
Data Source
AI summary
According to one embodiment, a flexible substrate including an insulating base including first and second strip portions, and island-shaped portions, electrical elements, scanning lines, signal lines, a first inorganic insulating film covering the scanning lines, and a second inorganic insulating film covering the signal lines, each of the scanning lines includes a first side edge and a second side edge, the first inorganic insulating film covers the first side edge and the second side edge, each of the signal lines includes a third side edge and a fourth side edge, and the second inorganic insulating film covers the third side edge and the fourth side edge.