Touch Sensor Module Supporting Structure for Flexible Circuit Board Protection
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Solution Overview
Problem
Existing touch sensor modules face challenges in maintaining electrical and mechanical reliability, especially when subjected to bending or folding, leading to potential delamination and damage of flexible circuit boards and sensing electrodes.
Innovation Solution
A touch sensor module design incorporating a supporting structure that partially covers the flexible circuit board and touch sensor layer, along with adhesive layers having specific flexural rigidity, to prevent delamination and damage during bending, and an optical layer spaced apart to maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible touch sensor module is bent or folded to achieve flexibility, then adaptability to flexible displays is improved, but delamination and damage of flexible circuit boards and sensing electrodes occur, worsening reliability
Solution Approach 1:
A supporting structure is introduced that extends beyond the boundaries of the touch sensor layer to cover portions of the flexible circuit board. This supporting structure acts as a cushioning element that distributes bending stresses and prevents direct stress concentration on the flexible circuit board and sensing electrodes, thereby preventing delamination and damage while maintaining flexibility
Solution Approach 2:
The touch sensor module employs a composite structure consisting of multiple layers including the touch sensor layer, flexible circuit board, and supporting structure. This composite design combines materials with different mechanical properties to achieve both flexibility and reliability, where the supporting structure provides mechanical reinforcement without compromising the flexible nature of the overall module
2Reliability
If the supporting structure covers the entire touch sensor layer to prevent damage, then reliability is improved, but device complexity increases
Solution Approach 1:
The supporting structure is designed to extend only partially beyond the touch sensor layer boundaries, specifically covering critical areas of the flexible circuit board where stress concentration occurs during bending. This localized approach provides necessary mechanical reinforcement while avoiding unnecessary material usage and structural complexity in non-critical areas
3Strength
If adhesive layers with high flexural rigidity are used to prevent delamination, then strength is improved, but flexibility deteriorates
Solution Approach 1:
The adhesive layers are designed with specific flexural rigidity parameters optimized to balance bonding strength and flexibility. By carefully controlling the mechanical properties of the adhesive layers, the module achieves sufficient bonding strength to prevent delamination while maintaining the overall flexibility needed for flexible display applications
Data Source
AI summary
A touch sensor module according to an embodiment of the present invention includes a touch sensor layer including sensing electrodes and traces branching from the sensing electrodes, a flexible circuit board electrically connected to the traces at one end portion of a top surface of the touch sensor layer, a supporting structure commonly and partially covering the flexible circuit board and the touch sensor layer, and an adhesive layer formed on at least one surface of the touch sensor layer. The adhesive layer has a flexural rigidity in a range from 0.01 to 5 N·nm. Damages and delamination of electrodes and wirings included in the flexible circuit board and the touch sensor layer are prevented by the supporting structure.