Corrugated Shadow Mask Structure for High-Density OLED Patterning
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Solution Overview
Problem
Existing shadow masks for vapor deposition, such as fine metal masks and silicon nitride masks, face limitations in achieving high-resolution OLED displays due to shadowing effects, mechanical distortion, and alignment issues, particularly in VR/AR applications requiring pixel resolutions beyond 1000 ppi.
Innovation Solution
A corrugated shadow mask with a central membrane region featuring through-apertures at the apexes of corrugations, supported by a peripheral region, which reduces the shadow effect and enhances mechanical strength, allowing for high-resolution patterning and alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a fine metal mask with finite thickness is used, then mechanical strength is improved, but aperture density is limited due to shadowing effect
Solution Approach 1:
The patent transitions from a flat 2D mask structure to a 3D corrugated structure with protruding apexes. This dimensional change allows the aperture exit openings to be positioned closer to the substrate, reducing the shadowing effect and enabling higher aperture density while maintaining mechanical strength through the corrugated geometry.
Solution Approach 2:
The corrugated structure introduces curved surfaces and protruding apexes instead of flat planes. The curved geometry of the corrugations reduces the shadowing effect by changing the angular distribution of vapor flow, allowing vapor to reach aperture regions that would otherwise be shadowed by mask thickness.
2Manufacturing precision
If mask thickness is reduced to increase aperture density, then aperture density is improved, but mechanical strength deteriorates
Solution Approach 1:
The mask membrane is segmented into multiple corrugated sections with protruding apexes rather than a single flat structure. This segmentation allows each corrugation to provide localized mechanical support while maintaining overall mask flexibility and strength, enabling thin membrane design with high aperture density.
Solution Approach 2:
The patent employs composite structure combining thin membrane material with corrugated geometry. The corrugated configuration acts as a structural reinforcement, providing mechanical strength equivalent to thicker flat masks while maintaining the thin profile necessary for high aperture density and reduced shadowing.
3Ease of manufacture
If a flat shadow mask is used, then manufacturing simplicity is improved, but shadowing effect increases
Solution Approach 1:
The flat mask surface is replaced with a corrugated surface featuring curved protruding apexes. This curvature change reduces the shadowing effect by allowing vapor to access aperture regions from multiple angles, minimizing the shadow zones that occur with flat masks.
Solution Approach 2:
The transition from 2D flat surface to 3D corrugated structure with height variations creates protruding apexes that extend toward the substrate. This dimensional addition reduces shadowing by positioning aperture exit openings closer to the deposition surface, allowing vapor to reach areas that would be shadowed in a flat configuration.
4Area of stationary object
If silicon nitride membrane is made larger to cover full display area, then coverage area is improved, but alignment accuracy deteriorates due to curvature
Solution Approach 1:
The large continuous membrane is segmented into multiple corrugated sections with discrete protruding apexes. This segmentation allows each section to be independently positioned and aligned, reducing cumulative alignment errors that would occur in a single large flat membrane while maintaining full display coverage.
Solution Approach 2:
The corrugated structure with protruding apexes provides inherent alignment features that can be precisely positioned relative to the substrate. The curved geometry creates well-defined reference points at the apexes that facilitate accurate alignment over large areas, reducing the curvature-related alignment issues of flat large-area masks.
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
The corrugated shadow mask achieves reduced shadowing, improved mechanical strength, and precise alignment, enabling high-resolution OLED displays with minimized color mixing and increased active pixel area, suitable for VR/AR applications.
Implementation Method 1
a shadow mask for patterned vapor deposition comprises a corrugated membrane... through which a vaporized material can pass
Data Source
AI summary
A corrugated shadow mask for patterned vapor deposition includes a corrugated membrane under tensile stress with a plurality of through-apertures forming an aperture array through which a vaporized deposition material can pass. The through-apertures are at the apexes of the corrugation and project from the membrane surface surrounding the through-apertures. The shadow mask is particularly suited for forming pixel arrays for OLED displays without color mixing from adjacent pixels.