Shadow Mask Groove Design for OLED Alignment Accuracy
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Solution Overview
Problem
In organic electro-luminescence (EL) display devices, the difference in rigidity coefficient values between the open and blocking parts of the shadow mask leads to unequal stretching, affecting the accuracy of alignment and resulting in lower yield due to formation of different or missing colors in the organic layer.
Innovation Solution
A mask with a blocking part featuring grooves is used, which has a reduced rigidity coefficient value compared to the traditional design, allowing for uniform stretching and improved alignment accuracy by forming an open part in a hole type and a blocking part with grooves on the metal plate through photo-resist patterning and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional shadow mask with solid blocking part is used, then the mask provides sufficient structural strength, but the difference in rigidity coefficient between open and blocking parts causes unequal stretching and reduces alignment accuracy
Solution Approach 1:
The blocking part is designed with grooves that create local variations in rigidity. Specifically, the grooves are formed at different positions and depths in different regions of the blocking part, allowing each region to have different rigidity characteristics. This local quality adjustment enables the blocking part to stretch uniformly across its entire surface while maintaining sufficient overall structural strength, thereby resolving the contradiction between strength and alignment accuracy.
Solution Approach 2:
The rigidity coefficient of the blocking part is modified by changing its structural parameters - specifically by introducing grooves with varying depths and positions. This parameter change allows the blocking part to achieve uniform rigidity distribution across its surface, enabling equal stretching behavior and improving alignment accuracy while preserving the necessary structural strength for mask operation.
2Stability of the object's composition
If the mask has high rigidity in the blocking part, then the mask maintains structural integrity, but unequal stretching occurs between open and blocking parts leading to color discrepancies in the organic layer
Solution Approach 1:
The blocking part incorporates grooves with locally varied depths and positions to create specific rigidity distributions. This local quality modification allows different regions of the blocking part to have adjusted rigidity characteristics, enabling uniform stretching across the entire mask surface during the organic layer formation process. As a result, the structural integrity is maintained while preventing color discrepancies in the deposited organic layer.
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 uniform rigidity coefficient value across the mask minimizes unequal stretching, enhancing the accuracy of alignment between the mask and substrate, thereby improving the yield and preventing color discrepancies in the organic layer formation.
Implementation Method 1
forming a photo-resist on the metal plate; patterning the photo-resist by using a partial exposing mask to form a photo-resist pattern
Implementation Method 2
etching the metal plate by using the photo-resist pattern as a mask to form the open part and the blocking part
Data Source
AI summary
This invention relates to a mask, a method of fabricating the same, and a method of fabricating organic electro-luminescence device using the same that is capable of minimizing a difference of a rigidity coefficient value of both an open part and a blocking part. The mask includes: an open part formed in a hole type to pass an organic material for forming a first organic layer on a substrate; and a blocking part having a plurality of grooves formed at other areas except for the open part.