Stress Relief Cuts for 3D Flexible Electronics
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Solution Overview
Problem
Forming spherical arrays of image sensors or displays is complex due to manufacturing, addressing, and image processing challenges, and bending substrates can lead to stress concentrations and cracking, especially at small curvatures.
Innovation Solution
The use of stress relief features such as circular, extended, and cubic wedge cuts in the substrate to increase the radius of curvature and reduce mechanical stress, allowing the substrate to be bent into three-dimensional shapes like spheres without cracking, by strategically cutting and removing material to maintain structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the substrate is bent into a spherical shape to achieve wide field of view, then the field of view is improved, but stress concentrations occur at points with very small curvatures causing cracking in the overlying films
Solution Approach 1:
The substrate is divided into multiple segments by cutting it into pieces. These segments are then reassembled into a spherical configuration, allowing the substrate to achieve the desired curved shape without experiencing excessive stress concentrations that would cause cracking in a continuous bent substrate.
Solution Approach 2:
The substrate transitions from a two-dimensional flat plane to a three-dimensional spherical structure through cutting and reassembly. This dimensional transformation enables the substrate to achieve wide field of view coverage while distributing mechanical stresses across multiple flat segments rather than concentrating them along a continuous curved surface.
2Ease of manufacture
If cuts are made in the substrate to allow bending into three-dimensional shapes, then the ability to form curved structures is improved, but stress concentrations occur at cut points causing cracking
Solution Approach 1:
The cutting pattern is designed with varying local characteristics - cuts are made closer together in regions requiring tighter curvature and farther apart in regions requiring gentler curvature. This non-uniform cutting pattern optimizes the distribution of stress relief while maintaining the ability to form the desired three-dimensional shape without causing cracking.
Data Source
AI summary
A method of forming a three-dimensional electronic device includes forming at least one electronic device on a two-dimensional, flexible substrate, the electronic device being formed according to a three-dimensional structure, cutting the two-dimensional, flexible substrate, the cuts being located to allow the two-dimensional substrate to be shaped, the cuts having at least one stress relief feature, and shaping the two-dimensional, flexible substrate to form the three-dimensional structure, the stress relief features arranged to alleviate stress in the three-dimensional structure. A method of forming a three-dimensional electronic device includes forming at least one electronic device on a two-dimensional, flexible substrate, the electronic device being formed according to a three-dimensional structure, cutting the two-dimensional, flexible substrate, the cuts being arranged to as to increase a radius of curvature to meet a stress relief parameter when the substrate is shaped, and shaping the two-dimensional, flexible substrate to form the three-dimensional structure.