Stretchable Wiring Board Narrow Overlap Reduces Resistance
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Solution Overview
Problem
Conventional stretchable wiring boards experience printing bleedings and increased wiring resistance due to high in-plane rigidity when insulating layers are used, which can lead to non-uniform stretching and potential short-circuits when attached to a living body.
Innovation Solution
A stretchable wiring board design featuring a stretchable substrate with a first stretchable wiring and a second stretchable wiring, where the second wiring has a narrower width portion overlapping the first wiring, reducing in-plane rigidity and minimizing printing bleedings, and a device with an adhesive patch for living bodies incorporating this board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two separate insulating layers are provided on the wiring board to suppress printing bleedings, then printing precision is improved, but in-plane rigidity increases causing stress concentration during stretching
Solution Approach 1:
The patent applies different properties to different regions: the insulating layers are provided only in regions where wirings do not overlap, while overlapping regions maintain low rigidity for uniform stretching. This local differentiation resolves the contradiction by providing printing precision where needed without compromising overall stretchability.
Solution Approach 2:
The insulating layers are segmented to be provided only in non-overlapping regions rather than covering the entire wiring board. This segmentation allows the board to maintain printing precision in critical areas while preserving stretchability in overlapping regions where uniform deformation is essential.
2Adaptability or versatility
If the wiring board is stretched to follow living body movements, then adaptability is improved, but stress concentrates on rigid regions causing non-uniform stretching and increased wiring resistance
Solution Approach 1:
Different regions of the wiring board are given different mechanical properties: non-overlapping regions have high rigidity for printing precision, while overlapping regions have low rigidity for uniform stretching. This ensures that when the board is stretched to follow living body movements, stress is distributed evenly without concentrating on rigid regions, maintaining wiring resistance stability.
3Manufacturing precision
If the width of the second wiring is reduced in the overlapping region, then printing bleedings are suppressed, but in-plane rigidity is reduced affecting structural integrity
Solution Approach 1:
The second wiring is designed with local quality variation: its width is reduced only in the overlapping region with the first wiring to suppress printing bleedings, while maintaining full width in non-overlapping regions to preserve structural integrity. This localized dimension adjustment resolves the contradiction between printing precision and structural strength.
Data Source
AI summary
A stretchable wiring board that includes: a stretchable substrate; a first stretchable wiring extending in a length direction on a main surface side of the stretchable substrate; and a second stretchable wiring extending in the length direction on the main surface side of the stretchable substrate, the second stretchable wiring having a first portion with a first region overlapping on top of the first stretchable wiring on an end portion side of the first stretchable wiring, and a width of the first portion of the second stretchable wiring in a width direction orthogonal to the length direction is smaller than a width of the first stretchable wiring.