Flexible Substrate Wiring With Variable Titanium Thickness for Stress Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing flexible substrates face challenges in managing stress uniformly across their surface, particularly when attached to curved surfaces, which can lead to disconnection of electrical elements due to uneven tensile and compressive stresses.
Innovation Solution
The flexible substrate incorporates a wiring layer with a second metal layer, specifically titanium, having different film thicknesses in various areas to adjust stress levels. In areas under tensile stress, the titanium layer is thinner, while in areas under compressive stress, it is thicker, thereby optimizing stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform wiring layer is used across the flexible substrate, then the manufacturing process is simple, but stress distribution becomes uneven causing disconnection of electrical elements
Solution Approach 1:
The patent applies local quality by varying the film thickness of the second metal layer (titanium) in different regions of the wiring layer. Specifically, the second metal layer has a first film thickness in a first area and a second film thickness in a second area, where the second film thickness is greater than the first film thickness. This local variation in thickness compensates for stress distribution differences across the flexible substrate, preventing disconnection of electrical elements while maintaining manufacturing feasibility through a standardized multi-layer deposition process.
2Device complexity
If the second metal layer has uniform thickness, then the wiring layer structure is simple, but stress relaxation is insufficient in high-stress areas
Solution Approach 1:
The patent applies parameter changes by modifying the film thickness parameter of the second metal layer (titanium) across different regions. The second metal layer has a first film thickness in a first area and a second film thickness in a second area, where the second film thickness is greater than the first film thickness. This parameter variation enables effective stress relaxation in high-stress areas while maintaining overall wiring layer functionality, achieving uniform stress distribution without excessive structural complexity.
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 approach effectively relaxes stress in the wiring lines, suppresses disconnection, and ensures uniform stress within the flexible substrate's plane, enhancing its reliability and flexibility.
Implementation Method 1
the second metal layer has a first film thickness in a first area and a second film thickness in a second area, and the second film thickness is greater than the first film thickness... This approach effectively relaxes stress in the wiring lines, suppresses disconnection
Data Source
AI summary
According to one embodiment, a flexible substrate includes a support plate including a first surface, a line portion including a flexible insulating base located on the first surface and a wiring layer disposed on the insulating base, and a protective member covering the line portion, and the wiring layer includes a first metal layer and a second metal layer stacked on the first metal layer, the second metal layer has a first film thickness in a first area and a second film thickness in a second area, and the second film thickness is greater than the first film thickness.