Fine Metal Mask Segmentation for OLED Evaporation Alignment
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Solution Overview
Problem
Fine metal masks used in the display industry for evaporating pixel materials often suffer from alignment errors due to bending or unevenness, leading to misalignment and evaporation errors during the manufacturing of OLED display panels.
Innovation Solution
A mask design featuring a total etching area with vias and clearance areas, where the clearance areas have a through hole and etched grooves, reducing stress concentration and improving alignment accuracy by minimizing creasing and stress gradients, thereby enhancing the precision of the evaporation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mask structure is made rigid to maintain alignment accuracy, then alignment precision is improved, but stress concentration and creasing occur during handling and evaporation
Solution Approach 1:
The mask structure is segmented by introducing clearance areas (stress relief zones) surrounded by etched grooves, which divide the continuous rigid structure into regions that can independently manage stress. This segmentation allows the mask to maintain overall rigidity for alignment accuracy while local regions absorb stress to prevent creasing.
Solution Approach 2:
Different regions of the mask are given different properties: the etching areas maintain high rigidity for precise pattern transfer, while the clearance areas are designed with stress-relief geometry (rounded corners, specific groove patterns) to locally absorb stress. This local differentiation resolves the contradiction between overall rigidity and local stress resistance.
2Area of stationary object
If the mask area is increased to provide sufficient etching workspace, then evaporation coverage is improved, but misalignment and evaporation errors increase due to handling stress
Solution Approach 1:
The large mask area is segmented into multiple working areas separated by clearance areas. This segmentation reduces the continuous span of the mask structure, minimizing stress accumulation across the entire area while maintaining sufficient workspace in each segment for accurate evaporation.
3Strength
If clearance areas are added to reduce stress concentration, then creasing is reduced, but alignment accuracy may be affected by the additional structural complexity
Solution Approach 1:
The clearance areas are designed with specific geometric properties (rounded corners, controlled groove depths and widths) that optimize stress distribution while minimizing impact on alignment. The etched grooves are positioned and dimensioned to relieve stress without creating optical interference or mechanical distortion that would affect alignment accuracy.
Data Source
AI summary
A mask includes a first surface and a second surface opposite to the first surface, and has a total etching area and clearance areas. The mask has vias in the total etching area, and each via communicates the first surface with the second surface. The clearance areas are arranged in the total etching area, and the vias surround each clearance area. Each clearance area further has a through hole therein communicating the first surface with the second surface. Each clearance area is in a shape of a circle or a polygon. When each interior angle of the polygon is less than 120 degrees, the clearance area further comprises a first clearance region and a second clearance region surrounded by the first clearance region, and the mask has a plurality of etched grooves in the first clearance region. The disclosure further provides a manufacturing method of a mask.