OLED Shadow Mask with Stress-Balanced Ceramic Membrane
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current shadow mask technologies face challenges in achieving high pixel density for VR/AR applications due to intrinsic shadowing effects caused by the thickness of existing shadow masks, leading to registration and alignment errors, and non-uniformity in deposition patterns, especially when scaling beyond small dimensions.
Innovation Solution
A shadow mask with a ceramic membrane under tensile stress, ranging from 0.2 to 5 microns in thickness, featuring a central membrane region with through-apertures and a multilayer peripheral support to balance tensile stress, maintaining flatness and allowing for large-scale patterning without curvature issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thin ceramic membrane under tensile stress is used to reduce shadowing effects and increase pixel density, then the mask thickness is reduced and pixel density is improved, but the membrane curvature and flatness deteriorate due to intrinsic tensile stress
Solution Approach 1:
The patent applies composite material structure by combining a thin ceramic membrane (for low shadowing and high pixel density) with a stress-balancing support layer (to counteract tensile stress and maintain flatness). This composite structure resolves the contradiction between achieving high pixel density through thin membranes and maintaining membrane flatness against curvature caused by intrinsic tensile stress.
Solution Approach 2:
The patent uses the stress-balancing support layer as a counterweight to the intrinsic tensile stress of the ceramic membrane. The support layer applies compressive stress that balances the tensile stress, preventing membrane curvature and maintaining flatness, thus enabling high pixel density without sacrificing flatness.
2Manufacturing precision
If the shadow mask thickness is reduced to improve pixel density above 1000 ppi, then the shadowing effect is reduced, but the mask mechanical strength and structural stability deteriorate
Solution Approach 1:
The patent creates a composite structure where a thin ceramic membrane (providing high pixel density and low shadowing) is combined with a stress-balancing support layer (providing mechanical strength and structural stability). This composite approach allows the mask to achieve >1000 ppi while maintaining sufficient mechanical strength.
Solution Approach 2:
The patent uses a thin ceramic membrane film that is flexible enough to maintain flatness through stress balancing but thin enough to reduce shadowing effects. The membrane thickness is optimized to be sufficient for mechanical integrity while remaining thin for high pixel density performance.
3Manufacturing precision
If a free-standing silicon nitride membrane is used to reduce mask thickness, then pixel density is increased to above 2000 ppi, but registration and alignment errors increase due to membrane curvature
Solution Approach 1:
The stress-balancing support layer acts as a counterweight to the intrinsic tensile stress of the free-standing silicon nitride membrane, applying compressive stress that balances the tension and prevents curvature. This maintains membrane flatness and eliminates registration and alignment errors, enabling high pixel density (>2000 ppi) with accurate patterning.
Solution Approach 2:
The patent combines a free-standing silicon nitride membrane (enabling high pixel density) with a stress-balancing support layer (maintaining flatness and alignment accuracy). This composite structure resolves the contradiction between achieving >2000 ppi and maintaining registration accuracy by preventing membrane curvature.
4Productivity
If the shadow mask is scaled up in size for larger display fabrication, then production capacity is improved, but membrane curvature and alignment errors scale proportionally
Solution Approach 1:
The stress-balancing support layer provides a scaling-independent solution to membrane curvature by applying counteracting compressive stress. This allows the shadow mask to be scaled up for larger display fabrication without proportionally increasing alignment errors, maintaining productivity while preserving alignment accuracy.
Solution Approach 2:
The composite structure of thin ceramic membrane plus stress-balancing support layer enables scalable shadow masks for large-area displays. The stress-balancing mechanism works effectively at any scale, allowing production capacity to increase while alignment accuracy is maintained through curvature prevention.
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 solution enables improved flatness and mechanical strength, allowing for micron-scale patterning with increased pixel density and larger aperture ratios, reducing shadowing effects and enhancing the scalability of shadow masks for VR/AR displays.
Implementation Method 1
A shadow mask with a ceramic membrane under tensile stress, ranging from 0.2 to 5 microns in thickness
Implementation Method 2
an interlayer under compressive stress positioned above the base layer and attached to a lower surface of the peripheral membrane region. The compressive stress of the interlayer is selected to balance a tensile stress of the ceramic membrane
Implementation Method 3
patterned vapor deposition of an organic light-emitting diode (OLED) material... materials to be patterned are evaporated or sublimed into vapor phase and subsequently deposited onto a substrate through a shadow mask
Data Source
AI summary
A shadow mask for patterned vapor deposition of an organic light-emitting diode (OLED) material includes a ceramic membrane under tensile stress with a plurality of through-apertures forming an aperture array through which a vaporized deposition material can pass. A multilayer peripheral support is attached to a rear surface with a hollow portion beneath the aperture array. A compressively-stressed interlayer balances the tensile stress of the ceramic membrane. A shadow mask module with multiple shadow masks is also provided and includes a rigid carrier having plural windows with a shadow mask positioned in each window. To make the module, shadow mask blanks are affixed to each carrier window followed by etching of apertures and support layers. In this way extremely flat masks with precise aperture patterns are formed.