Flexible Device Stiffness Variation Peel Force Reduction
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Solution Overview
Problem
The challenge in fabricating electronic elements on flexible substrates is the non-uniform stiffness of the devices, leading to varying peel forces required during removal from a rigid carrier, which can cause damage and reduce production yield due to the need for different peel forces across the substrate.
Innovation Solution
A flexible device with distinct areas of varying stiffness, where a flexible substrate with a coarse structure in one area overlaps a rigid element, and a laser beam is used to irradiate the release layer in the stiffer area to reduce adhesion and minimize the required peel force for separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a release layer is used to join the flexible substrate and carrier with low adhesion, then the peel force needed for mechanical stripping is reduced, but the non-uniform stiffness of the device causes different peel forces to be needed in different areas, leading to element damage
Solution Approach 1:
The patent applies local quality by creating a coarse structure only in specific areas of the flexible substrate where rigid elements are located. This coarse structure locally increases surface roughness and modifies the release layer adhesion properties in those specific regions, allowing different peel forces to be applied in different areas without damaging elements. The coarse structure area corresponds to where rigid elements are positioned, enabling selective adhesion modification.
Solution Approach 2:
The patent implements preliminary action by pre-forming the coarse structure on the flexible substrate before the element fabrication and mounting processes. This pre-prepared surface structure ensures that when elements are later mounted on the substrate, they are positioned over areas with modified adhesion properties, so that during subsequent carrier removal, the correct peel force is already in place without needing additional real-time adjustments.
2Ease of manufacture
If mechanical stripping technique is used to separate the flexible substrate from the carrier, then the fabrication process can be completed, but the non-uniform stiffness requires different peel forces in different areas causing damage to elements
Solution Approach 1:
The coarse structure is formed only in specific regions of the flexible substrate corresponding to rigid element locations, creating local variations in surface roughness and adhesion properties. This allows the mechanical stripping process to apply uniform peel force across the entire substrate while the coarse structure areas automatically require less force due to reduced adhesion, preventing element damage in those specific locations.
Solution Approach 2:
The coarse structure acts as an intermediary between the flexible substrate and the release layer in areas where rigid elements are mounted. This intermediate surface modification changes the adhesion characteristics, serving as a mediator that reduces the direct adhesion force between the release layer and substrate in element regions, thereby protecting elements during the mechanical stripping process.
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
This approach allows for the reduction of peel force needed to separate the flexible substrate from the carrier, minimizing damage and enhancing production yield by ensuring consistent and reduced force application across the device.
Implementation Method 1
irradiating a laser beam from the carrier toward the release layer located in the first area, and the irradiation path of the laser beam falls in the first area
Data Source
AI summary
According to embodiments of the disclosure, a flexible device and a fabrication method thereof are provided. The flexible device has a first area and a second area, and the stiffness of a portion of the first area is greater than the stiffness of the second area. The flexible device may include a flexible substrate and a rigid element. The flexible substrate includes a first surface and a second surface opposite to each other. The second surface has a coarse structure. The surface roughness of the second surface is greater in the first area than in the second area. The rigid element is disposed on the first surface of the flexible substrate and located in the first area. The stiffness of the rigid element is greater than the stiffness of the flexible substrate. A projection area of the coarse structure on the flexible substrate overlaps an area of the rigid element.