FPCB Buffer Layer Layout to Prevent Display Adhesive Press Marks
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Solution Overview
Problem
The bent portion of the flexible printed circuit board in display devices increases in thickness, pressing the adhesive layer between the display panel and the cover window, making the pressed portion visible and potentially causing damage.
Innovation Solution
A buffer layer is positioned between the display panel and the flexible printed circuit board, specifically at the bent portion of the tail part, to alleviate pressure and prevent the adhesive layer from being visibly depressed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the flexible printed circuit board is bent to prevent interference with other components, then space utilization is improved, but the bent portion increases in thickness and presses the adhesive layer making it visible and potentially causing damage
Solution Approach 1:
A buffer layer is introduced as an intermediary component between the flexible printed circuit board and the adhesive layer. This buffer layer absorbs and distributes the pressure generated by the bent portion of the FPCB, preventing direct transmission of stress to the adhesive layer. The buffer layer acts as a mediator that decouples the harmful mechanical stress from the adhesive joint while maintaining the necessary spatial configuration.
Solution Approach 2:
The buffer layer is positioned in advance at the location where the FPCB will be bent, providing pre-positioned cushioning protection. By placing the buffer layer beforehand at the critical stress concentration point, the design anticipates and prevents adhesive layer damage before the bending stress is applied during device assembly or operation.
2Strength
If the bent portion of the flexible printed circuit board presses the adhesive layer, then the FPCB maintains structural integrity, but the pressed portion of the adhesive layer becomes visible through the cover window
Solution Approach 1:
The buffer layer serves as a visual and mechanical intermediary that prevents the transmission of surface deformation from the FPCB bend to the adhesive layer. By absorbing the dimensional changes in the bent FPCB, the buffer layer maintains the flatness of the adhesive layer surface, ensuring optical uniformity through the cover window while preserving FPCB structural integrity.
3Reliability
If a buffer layer is added between the display panel and the flexible printed circuit board, then pressure on the adhesive layer is relieved, but device complexity increases
Solution Approach 1:
The buffer layer is implemented as a thin film structure that provides substantial pressure distribution and adhesive protection without adding significant bulk or complexity. This thin film approach maintains the compactness of the device while delivering the necessary mechanical cushioning function, minimizing the impact on overall device complexity despite the additional layer.
Data Source
AI summary
A display device includes a display panel including a pad area, a flexible printed circuit board connected to the display panel, and a buffer layer disposed between the display panel and the flexible printed circuit board. The flexible printed circuit board includes a body part on which components are arranged, a pressing part disposed along an edge of the body part and bonded to the pad area, and a tail part extending from the body part, and the tail part overlaps the buffer layer.