Stretchable Wiring Board with Stopper Layer Against Wiring Breaks
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Solution Overview
Problem
Excessive stretching of substrates in deformable electronic devices leads to breaks in the wiring, which is a common issue in existing technologies.
Innovation Solution
A wiring board design incorporating a stretchable substrate with a stopper layer having higher flexural rigidity than the substrate, which suppresses excessive stretching and includes undulating wiring to manage tension and resistance changes during deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the substrate is stretched to increase the stretch length, then the adaptability of the wiring board is improved, but the wiring may break due to excessive stretching
Solution Approach 1:
The stopper is disposed on the substrate before the wiring is formed, establishing a predetermined stretching limit. This preliminary placement of the stopper prevents the substrate from being stretched beyond a safe length, thereby avoiding wiring breaks while still allowing controlled stretchability for adaptability.
2Reliability
If the stopper is disposed to prevent excessive stretching, then the reliability of the wiring is improved, but the stretch length of the wiring board is limited
Solution Approach 1:
The stopper is disposed at a specific location (adjacent to the first surface or second surface of the substrate) rather than uniformly across the entire substrate. This localized placement provides mechanical support and prevents excessive stretching at critical areas while still allowing the rest of the substrate to maintain its stretchability for necessary adaptability.
3Adaptability or versatility
If the substrate is stretched beyond the second stretch length, then the tension increase rate becomes very high, but this may cause wiring breaks
Solution Approach 1:
The stopper provides preliminary counter-action by physically blocking further stretching of the substrate before the tension becomes excessively high. By preventing the substrate from reaching stretch lengths beyond the second stretch length, the stopper counteracts the harmful high tension that would otherwise develop and cause wiring breaks.
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
The design effectively reduces the risk of wiring breaks by managing tension and resistance changes, ensuring durability and reliability of the wiring board under stretch conditions.
Implementation Method 1
a first substrate having stretchability... While stretch length of the wiring board is being increased in a first direction, electrical resistance of the wiring exhibits a first turning point at a first stretch length and tension applied to the wiring board exhibits a second turning point at a second stretch length
Data Source
Figure 1~2
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Figure 5
AI summary
A wiring board includes a first substrate having stretchability, wiring disposed adjacent to a first surface of the first substrate and extending in a first direction, and a stopper disposed adjacent to the first surface or second surface of the first substrate. While stretch length of the wiring board is being increased in the first direction, electrical resistance of the wiring exhibits a first turning point at a first stretch length and tension applied to the wiring board exhibits a second turning point at a second stretch length smaller than the first stretch length. The first turning point is a point at which an increase in electrical resistance per unit stretch length changes. The second turning point is a point at which an increase in tension per unit stretch length changes.