Inclined Mask Sheet for Display Deposition Shadow Reduction
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Solution Overview
Problem
Current mask manufacturing processes face challenges in achieving high process yield, reliability, and precision, particularly in the deposition of thin film layers for display panels, leading to increased manufacturing costs and defects due to shadow formation and thermal expansion issues.
Innovation Solution
A mask design featuring a mask sheet with inclined surfaces and a matching frame, made from an alloy like iron-nickel with a low coefficient of thermal expansion, which reduces shadow formation and enhances precision by ensuring the deposition material is deposited efficiently over the target substrate, minimizing dead space and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional mask with a flat surface is used, then the manufacturing process is simple, but shadow formation occurs during deposition leading to dead space and reduced precision
Solution Approach 1:
The mask sheet incorporates an inclined surface (second surface) that is angled relative to the first surface, creating a non-flat geometry. This curved/angled design allows deposition material to reach the target substrate more effectively, reducing shadow formation and dead space while improving deposition precision without excessive complexity
Solution Approach 2:
The mask transitions from a conventional two-dimensional flat structure to a three-dimensional structure with an inclined surface. This dimensional change enables the mask to control deposition material flow in multiple directions, reducing shadow effects and improving precision by utilizing spatial geometry
2Reliability
If a mask sheet with high coefficient of thermal expansion is used, then the mask is easier to manufacture, but thermal expansion causes reliability issues during deposition
Solution Approach 1:
The mask sheet is made from an alloy of iron and nickel specifically selected to have a low coefficient of thermal expansion. This material parameter change ensures thermal stability during the deposition process, preventing dimensional changes that would compromise reliability, while the alloy formulation allows for standard manufacturing processes
3Productivity
If the mask sheet thickness is increased, then the mask frame support is improved, but shadow formation increases reducing deposition efficiency
Solution Approach 1:
The inclined surface design allows the mask sheet to maintain adequate thickness for structural support while the angled geometry prevents the formation of large shadow areas. The inclination angle optimizes the balance between maintaining mask sheet strength and minimizing shadow formation to improve deposition efficiency
4Manufacturing precision
If the first portion thickness is reduced, then shadow formation is minimized, but the mask sheet structural integrity is compromised
Solution Approach 1:
The mask sheet employs local quality variation where the first portion has a reduced thickness optimized for minimizing shadow formation and improving open area precision, while the overall mask sheet maintains sufficient structural integrity through the alloy material properties and the inclined surface geometry that distributes mechanical stresses
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 proposed mask design improves manufacturing efficiency, reduces costs, and enhances the precision of thin film deposition, resulting in higher-quality display panels with reduced dead space and defects, while maintaining thermal stability across varying temperatures.
Implementation Method 1
reduced dead space caused by a shadow
Implementation Method 2
mask sheet with inclined surfaces and a matching frame, made from an alloy like iron-nickel with a low coefficient of thermal expansion
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A mask includes a mask sheet provided with a plurality of open areas defined therein in a plan view and a mask frame which supports the mask sheet. The mask sheet includes a first portion including a first surface, where the first surface is configured to be in contact with a target substrate, and a second portion disposed on the first portion, extending from a top of the first portion in a first direction and including a second surface defining the open area. The second surface is an inclined surface inclined downward with respect to the first direction, and the first direction is parallel to a plane in which the first surface is included.