Deposition Mask Assembly Layout for Wave Deformation Control
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Solution Overview
Problem
Large masks used in deposition processes for display devices are prone to deformation, leading to insufficient adherence to the substrate and reduced deposition process reliability due to wave deformation or wrinkling.
Innovation Solution
A mask design with a center part and terminal parts featuring clamp grooves and dummy openings, where the dummy openings are aligned with clamp grooves and have a smaller radius, reducing stress and preventing wave deformation during the deposition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mask size is increased to cover larger substrate areas, then the deposition process can be more efficient, but the mask becomes prone to wave deformation and insufficient adhesion to the substrate
Solution Approach 1:
The mask is divided into multiple terminal parts (first terminal part, second terminal part, third terminal part, fourth terminal part) spaced apart from each other with the center part in between. This segmentation reduces the continuous span of the mask, thereby reducing wave deformation while maintaining large coverage area for efficient deposition.
Solution Approach 2:
Dummy openings are specifically positioned in the terminal parts where stress concentration occurs during adhesion. The dummy openings have different characteristics (circular shape, specific radius) compared to the deposition openings in the center part, providing localized stress relief where needed most while preserving the functional deposition areas.
2Productivity
If the mask size is increased to cover larger substrate areas, then more pixels can be deposited in one process, but the mask experiences wave deformation leading to reduced manufacturing precision
Solution Approach 1:
By dividing the mask into separated terminal parts with spacing between them, the overall mask structure is less prone to wave deformation. This maintains the precision of the deposition pattern while allowing larger substrate coverage through the distributed terminal parts and center part configuration.
Solution Approach 2:
The dummy openings in the terminal parts are specifically designed to prevent wave deformation at the edges where it occurs most frequently. This localized stress management ensures that the deposition pattern accuracy is maintained across the entire substrate area covered by the mask.
3Reliability
If dummy openings are added to the terminal parts to reduce wave deformation, then mask adhesion stability improves, but the mask structure becomes more complex
Solution Approach 1:
Rather than adding complex structural elements throughout the entire mask, dummy openings are strategically placed only in the terminal parts where stress concentration occurs. This minimal modification approach improves adhesion stability while adding the least possible complexity to the overall mask structure.
Data Source
AI summary
A mask includes a center part extending in a first direction and including a cell region in which deposition openings are defined, and terminal parts spaced apart from each other in the first direction with the center part therebetween, where a dummy opening having a circular shape is defined in each of the terminal parts. A clamp groove partially recessed in a direction of the center part from an end of the terminal part is defined in each of the terminal parts, the clamp groove and the dummy opening are aligned with each other in the first direction, and a radius of the dummy opening may be smaller than or equal to a half of a width of the clamp groove in a second direction crossing the first direction.