Mask Assembly Grooves Control Etchant Flow
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Solution Overview
Problem
Existing mask assemblies for thin film deposition in organic light-emitting display apparatuses face challenges in achieving precise deposition of organic layers, leading to potential shadows and uneven etching in display devices due to the flow of etchant into non-display areas.
Innovation Solution
A mask assembly with a frame and a mask featuring specific deposition patterns, including first holes, second holes, and grooves, where the grooves in the dummy outer area prevent etchant flow, ensuring precise etching and reducing shadows by controlling the etchant distribution between active and dummy areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional mask assembly is used for thin film deposition, then the deposition process can be completed, but etchant flows into non-display areas causing uneven etching and shadows in the display device
Solution Approach 1:
The mask is divided into three distinct pattern portions: first pattern portion with holes for active area deposition, second pattern portion with holes for dummy area deposition, and third pattern portion with grooves for dummy outer area. This segmentation allows different etchant control strategies for different areas, preventing etchant flow into non-display areas while maintaining deposition precision.
Solution Approach 2:
Different structural features are applied to different areas of the mask: holes (first and second pattern portions) allow etchant passage for precise etching in active and dummy areas, while grooves (third pattern portion) in the dummy outer area prevent etchant flow. This local differentiation of mask structure properties addresses the etchant flow problem specifically in non-display areas without affecting display area quality.
2Productivity
If etchant is allowed to flow freely during deposition, then the process speed is maintained, but shadows and uneven etching occur in the display device
Solution Approach 1:
The mask pattern is segmented into three portions with different structures (holes and grooves) that control etchant flow at different stages and locations. This allows continuous deposition process while maintaining uniform etching by preventing etchant accumulation in dummy outer area that would cause shadows.
Solution Approach 2:
The grooves in the third pattern portion act as an intermediary structure between the dummy area and dummy outer area, mediating etchant flow to prevent it from reaching non-display areas. This intermediary structure maintains process speed while ensuring uniform etching distribution.
3Ease of manufacture
If the mask structure is simplified, then manufacturing is easier, but precise control of etchant distribution between active and dummy areas cannot be achieved
Solution Approach 1:
The mask is segmented into three pattern portions with distinct functions, allowing systematic control of etchant distribution. While the structure is more complex than a simple mask, each portion serves a specific purpose that can be manufactured using standard processes, balancing manufacturability with precision control.
Solution Approach 2:
Different local structures (holes vs. grooves) are applied to different mask portions based on their specific functions. This localized differentiation enables precise etchant distribution control while using conventional manufacturing techniques appropriate for each structural type.
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 precise formation of organic emission layers on display substrates, reducing shadows and improving the quality and reliability of the display device by maintaining even etching across both display and non-display areas.
Implementation Method 1
mask assembly for thin film deposition... a mask for deposition... organic emission layer which is disposed between the anode and the cathode. The organic emission layer may be formed by using a mask for deposition.
Data Source
AI summary
A mask assembly includes a frame and a mask supported by the frame. The mask includes a plurality of deposition patterns. Each of the plurality of deposition patterns includes a first pattern portion disposed in an active area corresponding to a display area of a display substrate, a second pattern portion disposed in a dummy area corresponding to a non-display area of the display substrate, and a third pattern portion disposed in a dummy outer area also corresponding to the non-display area of the display substrate. The dummy area extends from the active area to the dummy outer area and the dummy outer area extends from the dummy area to an edge of each of the plurality of deposition patterns. The first pattern portion includes a plurality of first holes, the second pattern portion includes a plurality of second holes, and the third pattern portion includes a plurality of grooves.