Flexible Substrate Bubble-Prevention Layer Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flexible printed circuit boards used in display devices are prone to cracking and breaking due to repeated bending, which reduces their durability and reliability.
Innovation Solution
A flexible substrate with a specific design featuring a circuit layer, a bubble-prevention layer, and a cover layer, where the substrate has varying thicknesses in different regions to manage stress and adhesion, and includes bonding regions and a bending region with a thinner thickness to enhance durability and prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flexible substrate has a uniform thickness throughout, then the manufacturing process is simple, but the substrate is prone to cracking and breaking due to repeated bending
Solution Approach 1:
The flexible substrate employs different thicknesses in different regions: a first thickness in bonding regions for strong adhesion, and a second smaller thickness in the bending region for flexibility and stress reduction. This local differentiation resolves the contradiction by optimizing each region's thickness for its specific function rather than using a uniform thickness throughout the substrate.
2Reliability
If the flexible substrate is made thinner to improve flexibility, then the bending stress is reduced, but the adhesion strength in bonding regions decreases
Solution Approach 1:
The substrate structure applies local quality by specifying that the first thickness in bonding regions is greater than the second thickness in the bending region. This ensures that bonding regions have sufficient thickness for strong adhesion while the bending region has reduced thickness for flexibility and stress management, resolving the contradiction between adhesion strength and bending durability.
3Reliability
If a bubble-prevention layer is added to prevent delamination, then the adhesion between layers is improved, but the manufacturing complexity increases
Solution Approach 1:
A bubble-prevention layer is introduced as an intermediary layer between the cover layer and the circuit layer in the bonding regions. This intermediate layer prevents delamination and bubble formation during bonding, improving layer adhesion while maintaining a relatively simple manufacturing process through standard lamination techniques.
4Strength
If the flexible substrate is made thicker to prevent cracking, then the structural strength is improved, but the bending flexibility and stress management worsen
Solution Approach 1:
The substrate implements local quality by having a first thickness in bonding regions for structural strength and a second smaller thickness in the bending region for flexibility. This spatial differentiation allows the substrate to have sufficient strength where needed while maintaining bending flexibility where required, resolving the contradiction between structural strength and bending flexibility.
Data Source
AI summary
A display device includes a display module configured to display an image, and a flexible substrate including a first bonding region connected to the display module, with the flexible substrate bent such that a portion thereof is disposed under the display module. The flexible substrate may include a circuit layer electrically connecting the display module to a printed circuit board, a cover layer on the circuit layer, and a bubble-prevention layer disposed between the cover layer and the circuit layer and configured to overlap with the first bonding region, wherein the display module includes a non-display region surrounding a display region, the non-display region includes a pad region to which the flexible substrate is connected, and the bubble-prevention layer overlaps the pad region, and the bubble-prevention layer does not overlap the display area.