Deposition Mask With Variable Thickness To Prevent Wrinkles
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Solution Overview
Problem
The existing masks for deposition in organic light emitting diode manufacturing often suffer from wrinkles at the boundary between deposition pattern and peripheral regions, leading to reduced adhesive force with the substrate, resulting in shadow phenomena and thin film deposition defects.
Innovation Solution
A mask design featuring deposition pattern parts with pattern openings, dummy pattern parts with recesses, and fixing parts, where the thickness transitions gradually from deposition pattern to fixing parts, minimizing volume and thickness differences and reducing wrinkle formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a sharp boundary is formed between the deposition pattern part and the outer peripheral region, then the deposition pattern is well-defined, but wrinkles are generated at the boundary portion due to volume difference
Solution Approach 1:
The mask is divided into three distinct regions: deposition pattern part, intermediate pattern part, and outer peripheral region. This segmentation allows each region to have different thickness characteristics, with the intermediate pattern part serving as a transition zone that gradually changes thickness from the deposition pattern part to the outer peripheral region, thereby preventing wrinkles while maintaining pattern definition.
Solution Approach 2:
Different regions of the mask are given different local thickness properties. The deposition pattern part has maximum thickness for precise pattern formation, the intermediate pattern part has gradual thickness transition, and the outer peripheral region has minimum thickness. This local quality differentiation resolves the contradiction between sharp boundary definition and surface uniformity.
2Ease of manufacture
If the mask has uniform thickness throughout, then manufacturing is simplified, but adhesive force between mask and substrate is reduced due to wrinkle formation
Solution Approach 1:
Instead of uniform thickness, the mask employs local quality variation with three distinct thickness regions. The deposition pattern part maintains maximum thickness for reliability, while the outer peripheral region has minimum thickness, and the intermediate pattern part provides gradual transition. This resolves the contradiction by achieving both manufacturability and adhesive force through localized thickness optimization.
Solution Approach 2:
The solution moves from a two-dimensional uniform thickness approach to a three-dimensional variable thickness approach. By introducing thickness as a varying parameter across different regions of the mask, the invention achieves both ease of manufacture and high adhesive force, resolving the contradiction between manufacturing simplicity and reliability.
3Manufacturing precision
If the mask is closely contacted to the substrate, then deposition precision is improved, but shadow phenomenon occurs due to mask lifting from wrinkles
Solution Approach 1:
The mask is segmented into regions with different thickness properties, creating a smooth thickness gradient from the deposition pattern part through the intermediate pattern part to the outer peripheral region. This segmentation eliminates abrupt thickness changes that cause wrinkles, thereby preventing mask lifting and shadow phenomenon while maintaining close contact for precise deposition.
Solution Approach 2:
Instead of trying to eliminate the boundary between deposition pattern and outer peripheral region, the invention inverts the approach by introducing an intermediate pattern part that reverses the thickness gradient direction. This gradual transition prevents the sharp volume difference that causes wrinkles, eliminating shadow phenomenon while preserving deposition precision.
Data Source
AI summary
A mask for deposition includes a plurality of deposition pattern parts arranged spaced apart from each other in a first direction, and a plurality of pattern openings defined in each deposition pattern part; a plurality of dummy pattern parts disposed at opposing sides of the plurality of deposition pattern parts in the first direction, respectively, and a plurality of recesses defined in each dummy pattern part; and a plurality of fixing parts respectively disposed at external sides of outermost dummy pattern parts among the plurality of dummy pattern parts, in the first direction. A maximum thickness of the each dummy pattern part is equal to or larger than a maximum thickness of the each deposition pattern part, and is smaller than a maximum thickness of each fixing part.