Reinforcing Layer Layout for FPC Bending Stress in Displays
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Solution Overview
Problem
The existing display devices face issues with stress concentration and cracking in the bending part of the flexible printed circuit board due to the shortening of the bending part, which leads to dead space and potential damage to conductive lines.
Innovation Solution
A display device design that includes a reinforcing layer between the substrate and a coating layer on the flexible circuit board, with a lower elastic modulus than the coating layer, to support the bending region and reduce stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the bending part of the flexible printed circuit board is shortened to reduce dead space, then the area of dead space is reduced, but stress concentration increases leading to cracking of conductive lines
Solution Approach 1:
A reinforcing layer is introduced as an intermediary component between the flexible printed circuit board and the coating layer in the bending region. This reinforcing layer specifically supports the conductive lines during bending, distributing the stress and preventing crack formation while allowing the bending part to be shortened for reduced dead space.
Solution Approach 2:
The reinforcing layer is selectively applied only to the bending region of the flexible printed circuit board, providing localized reinforcement where stress concentration occurs. This allows the bending part to be shortened without compromising the reliability of conductive lines in the high-stress area, while maintaining overall device compactness.
2Area of stationary object
If the bending part is shortened to reduce dead space, then the area of dead space is reduced, but the stress on the bending part increases
Solution Approach 1:
The reinforcing layer serves as a mediator that distributes and reduces stress concentration in the bending region. By introducing this intermediate structural element, the bending part can be shortened to minimize dead space while the reinforcing layer absorbs and disperses the increased stress, preventing damage to the flexible printed circuit board.
3Reliability
If a reinforcing layer with low elastic modulus is added to support the bending region, then crack resistance is improved, but the device complexity increases
Solution Approach 1:
A reinforcing layer is introduced as an intermediary component between the flexible printed circuit board and the coating layer in the bending region. This reinforcing layer specifically supports the conductive lines during bending, distributing the stress and preventing crack formation while allowing the bending part to be shortened for reduced dead space.
Solution Approach 2:
The reinforcing layer is selectively applied only to the bending region of the flexible printed circuit board, providing localized reinforcement where stress concentration occurs. This allows the bending part to be shortened without compromising the reliability of conductive lines in the high-stress area, while maintaining overall device compactness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The reinforcing layer effectively reduces the risk of cracking in the bending part, minimizes dead space, and protects the conductive lines by absorbing external impacts and facilitating stable bending of the flexible circuit board.
Implementation Method 1
A reinforcing layer is disposed between the first side of the substrate and the coating layer on the lower portion of the flexible circuit board. The reinforcing layer has an elastic modulus that is less than that of the coating layer.
Data Source
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AI summary
A display device includes a substrate (SUB) having a first side (OS1) and a second side opposite to the first side. A plurality of pixels (PXL) is disposed on the substrate. A flexible circuit board (FPC) is connected to the substrate. A driving integrated circuit (D-IC) is disposed on a lower portion of the flexible circuit board. A coating layer (CL) is disposed on the lower portion of the flexible circuit board. The coating layer is spaced apart from the first side of the substrate and at least partially surrounds the driving integrated circuit. A reinforcing layer (SM1) is disposed between the first side of the substrate and the coating layer on the lower portion of the flexible circuit board. The reinforcing layer covers a side of the coating layer that faces the first side of the substrate.