Deposition Mask Quality Screening for Through-Hole Position Accuracy
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Solution Overview
Problem
The challenge in manufacturing high-definition organic EL display devices lies in accurately reproducing the positions of through holes in a deposition mask during the deposition process, which affects the pixel density and overall quality of the display.
Innovation Solution
A method for quality determination and manufacturing of deposition masks involves measuring and determining the dimensions X1 and X2 of specific points on the mask, ensuring they satisfy certain equations to enhance positional accuracy, and selecting masks that meet these criteria for improved alignment during stretching and deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deposition mask is stretched to fit the substrate, then the mask can be brought into tight contact with the substrate for deposition, but the positional accuracy of through holes deteriorates due to deformation
Solution Approach 1:
The patent applies preliminary action by pre-stretching the deposition mask to a predetermined degree before actual use. This pre-stretching is performed at a controlled rate (0.01-10 mm/s) to a specific strain level (1-10%) that optimizes both the mask's contact with the substrate and maintains through-hole positional accuracy. The mask is then fixed in this pre-stretched state, eliminating the need for stretching during the actual deposition process.
Solution Approach 2:
The patent employs parameter changes by systematically varying the pre-stretching conditions including stretching rate (0.01-10 mm/s), stretching distance (1-10 mm), and stretching direction (parallel to substrate sides). These parameter optimizations ensure the mask achieves the desired contact pressure while minimizing deformation-induced positional errors in the through holes.
2Manufacturing precision
If the positional accuracy of through holes is improved by controlling mask stretching, then deposition quality enhances, but the complexity of the manufacturing process increases due to additional quality determination steps
Solution Approach 1:
The patent replaces complex mechanical measurement systems with a simplified quality determination method based on dimensional ratios. Instead of using sophisticated equipment to measure absolute positions of multiple through holes, the invention only requires measuring distances between specific points (P1-Q1 and P2-Q2) and comparing their ratio to a predetermined value, significantly simplifying the inspection process.
Solution Approach 2:
The patent uses a reference pattern (second pattern) with known geometric relationships as a template for quality assessment. By comparing the actual mask's dimensional ratios against this reference, the system can quickly determine whether the mask meets specifications without performing complex absolute position measurements of all through holes.
3Manufacturing precision
If high pixel density is achieved through accurate through hole positioning, then display quality improves, but the difficulty of detecting and measuring positional accuracy increases
Solution Approach 1:
The patent extracts the essential quality indicator from complex positional measurements by focusing solely on the ratio of two specific dimensional measurements (X1/X2). This extracted ratio serves as a sufficient statistic for quality determination, eliminating the need to measure and analyze the absolute positions of numerous individual through holes that would be required to achieve high pixel density specifications.
Data Source
AI summary
A method of quality determination of a deposition mask according to the present disclosure includes: a measuring step that measures a dimension X1 from a P1 point to a Q1 point, and a dimension X2 from a P2 point to a Q2 point; and a determining step that determines a quality of a deposition mask, based on the dimension X1 and the dimension X2 measured in the measuring step.