Foldable Display Laser Cutting Stress Reduction
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Solution Overview
Problem
Current foldable display devices face challenges in maintaining reliability due to stress and damage during the manufacturing process, which can lead to defects like cracks when repeatedly folded, affecting their durability and performance.
Innovation Solution
A method for manufacturing foldable display devices involves a multi-step laser cutting process using different energy levels and rates to minimize stress on the folding area, with high energy used in non-folding areas and low energy in the folding area, along with a specific pattern of cutting lines to form a closed curve shape, removing the non-effective area and ensuring the folding area is less damaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single high energy laser process is used for cutting the mother substrate, then the cutting efficiency is high, but the folding area suffers from stress and damage leading to cracks
Solution Approach 1:
The laser cutting process is segmented into three distinct processes: a first laser process for non-folding areas, a second laser process for non-folding areas, and a third laser process specifically for the folding area. This segmentation allows each process to be optimized independently - the first and second processes use higher energy for efficiency, while the third process uses lower energy to protect the folding area from stress-induced cracks.
Solution Approach 2:
Different laser energy levels are applied to different regions of the mother substrate. The first and second laser processes use a first energy level for non-folding areas where high cutting efficiency is acceptable, while the third laser process uses a second energy level (lower than the first) specifically for the folding area to minimize stress and prevent damage. This local differentiation of process parameters resolves the contradiction between overall productivity and local reliability.
2Speed
If laser cutting is performed on the folding area with high energy, then the cutting speed is fast, but stress and damage occur leading to defects
Solution Approach 1:
The laser energy parameter is changed based on the location being cut. The first laser process and second laser process use a first energy level for non-folding areas, while the third laser process uses a second energy level that is lower than the first when cutting the folding area. This parameter change reduces the harmful thermal stress and mechanical damage to the folding area while maintaining acceptable cutting speed through the three-process approach.
3Reliability
If multiple laser processes with different energy levels are used, then the reliability of the folding area is improved, but the manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into three laser processes with different energy levels applied to different regions. While this increases process complexity, it resolves the reliability issue by preventing cracks in the folding area. The segmentation allows for targeted protection of the critical folding area while maintaining efficiency in non-critical areas.
Solution Approach 2:
The manufacturing process applies local quality control by using different laser energy levels for different regions. The first and second laser processes use higher energy for non-folding areas, while the third laser process uses lower energy for the folding area. This localized approach improves reliability where needed without uniformly increasing complexity across the entire manufacturing 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 reduces stress and damage to the folding area, minimizing the occurrence of defects such as cracks, thereby enhancing the reliability and durability of the foldable display devices.
Implementation Method 1
performing a first laser process along a first cutting line of the cutting line disposed in the first non-folding area, performing a second laser process along a second cutting line of the cutting line disposed in the second non-folding area, and performing a third laser process along a third cutting line of the cutting line disposed in the folding area
Implementation Method 2
The third laser process may be performed by irradiating a second laser beam having an energy less than that of a first laser beam used in the first laser process
Data Source
AI summary
A method for manufacturing a display device including a display panel having a folding area to be folded along a virtual folding axis and first and second non-folding areas adjacent to both sides of the folding area, and a window disposed on the display panel, the method including preparing a mother substrate having an effective area and a non-effective area divided by a cutting line, performing a first laser process along a first cutting line disposed in the first non-folding area, performing a second laser process along a second cutting line disposed in the second non-folding area, and performing a third laser process along a third cutting line disposed in the folding area, in which one end of the third cutting line overlaps a first end of the first cutting line, and the other end of the third cutting line overlaps a first end of the second cutting line.