Exposure Mask Boundary Patterning for Stitch-Free Display Panels
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Solution Overview
Problem
The manufacturing of large display devices faces limitations due to the size constraints of exposure masks, leading to stitch defects and increased complexity in the divided exposure process, which affects display quality and the reliability of the sealant adhesion between electrodes.
Innovation Solution
An exposure mask design with non-overlapping and boundary portions featuring irregular patterns, allowing for reduced mask shots by overlapping gradual patterns at the edges, thereby simplifying the manufacturing process and improving display quality by minimizing stitch defects and sealant adhesion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large area substrate is exposed with a single mask several times during an exposure process, then the manufacturing of large display devices becomes possible, but stitch defects occur at boundaries between adjacent shots and the manufacturing process complexity increases
Solution Approach 1:
The exposure mask is divided into a non-overlapping portion and boundary portions with irregular patterns. The boundary portions are designed to overlap gradually when multiple masks are arranged, creating a seamless transition that eliminates stitch defects at boundaries between adjacent exposure shots.
Solution Approach 2:
Different portions of the exposure mask have different pattern characteristics. The non-overlapping portion has regular patterns for efficient packing, while the boundary portions have irregular patterns that ensure smooth transitions when masks are overlapped, optimizing each region's function to prevent manufacturing defects.
2Manufacturing precision
If boundary portions with irregular patterns are used in exposure mask design, then stitch defects are minimized and display quality is enhanced, but the exposure mask design complexity increases
Solution Approach 1:
The exposure mask is segmented into distinct functional portions: a non-overlapping portion with regular patterns and boundary portions with irregular patterns. This segmentation allows each portion to be optimized independently, managing design complexity while achieving defect reduction.
Solution Approach 2:
The boundary portions employ asymmetric irregular patterns that differ from the regular patterns in the non-overlapping portion. This asymmetry is intentionally designed to create smooth transitions at mask boundaries, reducing stitch defects while the modular structure keeps the overall design manageable.
3Productivity
If the number of mask shots is reduced by overlapping gradual patterns at edges, then the manufacturing process is simplified and productivity is improved, but the precision of pattern alignment must be maintained
Solution Approach 1:
The boundary portions with irregular patterns are pre-designed into the exposure mask to facilitate overlapping. This preliminary design ensures that when multiple masks are arranged, they naturally align with proper overlap, reducing the need for complex real-time alignment adjustments and simplifying the manufacturing process.
Solution Approach 2:
The pattern parameters are changed at the boundaries of the exposure mask, transitioning from regular patterns in the non-overlapping portion to irregular patterns in the boundary portions. This parameter change enables smooth transitions when masks are overlapped, maintaining alignment precision while allowing reduced mask shots.
4Reliability
If column spacers are optimized in distribution and sealant adhesion is improved, then short circuits between electrodes are prevented and reliability is enhanced, but the manufacturing process complexity increases
Solution Approach 1:
The exposure mask applies different pattern densities and configurations in different regions. Column spacers are distributed according to local requirements, with optimized density in areas prone to short circuits and adjusted patterns near sealant regions. This localized optimization enhances reliability without requiring complex manufacturing processes.
Solution Approach 2:
The irregular patterns in the boundary portions of the exposure mask automatically ensure proper overlap and alignment when multiple masks are used. This self-aligning feature reduces the need for complex alignment procedures and additional manufacturing steps, enhancing reliability while keeping the process relatively simple.
Data Source
AI summary
A display device includes: a display area including a plurality of pixels; a first peripheral area disposed at one side of the display area; and a second peripheral area disposed at the opposite side of the display area, wherein a first column spacer is disposed in the display area, a second column spacer is disposed in the first peripheral area, and a third column spacer is disposed in the second peripheral area. The patterns of an exposure mask utilized in the first peripheral area in which the second column spacer is disposed and the second peripheral area in which the third column spacer is disposed may be different from each other.