Offset Bonding Pads for Foldable Display Stress Reduction
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Solution Overview
Problem
Display devices face issues with cracks and pad units being lifted off during folding due to the bonding of flexible printed circuits (FPCs), which affects the reliability and durability of the devices.
Innovation Solution
A display device design that includes an input sensing member and a pressure sensing member with strategically positioned bonding pads, where the first offset distance between the pads is greater than zero, and a manufacturing method that involves electrically connecting these pads to reduce stress and prevent cracking and lifting during folding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FPCs are bonded to the display device, then electrical connection is achieved, but cracks and pad unit lifting occur during folding
Solution Approach 1:
The patent introduces a spatial offset between the first bonding pad unit and the second bonding pad unit in the vertical direction (dimensional change). This offset positioning allows the bonding pads to be located at different heights relative to the display panel, creating a stepped bonding structure that reduces stress concentration during folding operations and prevents cracks and pad unit lifting.
2Area of stationary object
If bonding pads are positioned close together, then bonding area is maximized, but stress concentration causes cracking during folding
Solution Approach 1:
The patent divides the bonding structure into two separate bonding pad units (first bonding pad unit and second bonding pad unit) positioned at different locations. This segmentation distributes the bonding area across multiple zones rather than concentrating it in one location, thereby reducing stress concentration at any single point during folding while maintaining adequate total bonding area.
3Reliability
If bonding pads are offset vertically, then stress distribution during folding is improved, but bonding alignment complexity increases
Solution Approach 1:
The patent employs asymmetric positioning of the first bonding pad unit and second bonding pad unit, where the second bonding pad unit is located at a different vertical position (offset distance) relative to the first bonding pad unit. This asymmetric, stepped configuration optimizes stress distribution during folding while providing clear alignment guidelines that actually simplify the bonding process by defining specific positional relationships between components.
Data Source
AI summary
A display device is provided. The display device includes: an input sensing member electrically connected to a first bonding pad unit having a first pad; a pressure sensing member electrically connected to a second bonding pad having a second pad; and a display panel disposed between the input sensing member and the pressure sensing member, wherein the first pad is electrically connected to the second pad, a first offset distance between the first and second pads is greater than zero, and the first offset distance is defined as a spacing distance, on a plane, between a side of the first pad and a side of the second pad when the first and second pads are yet to be electrically connected.