OLED Shadow Mask Alignment Using Precision Pins
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Solution Overview
Problem
Existing methods for aligning a shadow mask to an OLED substrate, whether active or passive, face challenges such as high costs for active systems and tolerance stack-up issues in passive systems, which affect precision and efficiency in the fabrication of complex layered structures like OLEDs.
Innovation Solution
A passive alignment method using a shadow mask with spaced alignment openings and precision alignment elements, such as hardened cylindrical pins, that engage with the OLED substrate's edges to achieve precise alignment without the need for an optical alignment system, reducing tolerance stack-up and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active alignment systems using computer vision are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex optical/mechanical active alignment systems with a simplified passive mechanical alignment system. Instead of using computer vision systems and precision motion mechanisms, the invention uses a shadow mask frame with alignment openings that receive precision alignment elements, which directly engage with the substrate to achieve alignment through mechanical constraint alone.
2Productivity
If passive alignment with multiple alignment stages is used, then productivity is improved, but manufacturing precision deteriorates due to tolerance stack-up
Solution Approach 1:
The patent combines the alignment functions for the shadow mask and substrate into a single unified alignment operation. The shadow mask frame and substrate are both aligned to the same set of precision alignment elements simultaneously, eliminating the need for separate alignment stages and preventing tolerance stack-up that would occur with multiple sequential alignment operations.
Solution Approach 2:
The precision alignment elements serve as intermediaries between the shadow mask frame and the substrate. These elements provide a common reference framework that both components align to, ensuring that their relative positioning is determined by a single alignment operation rather than multiple sequential operations, thus preventing tolerance accumulation.
3Device complexity
If passive alignment with conventional alignment features is used, then device complexity is reduced, but manufacturing precision deteriorates due to tolerance stack-up
Solution Approach 1:
The shadow mask frame structure itself provides the alignment functionality through integrated alignment openings. Rather than requiring separate alignment mechanisms or features, the frame is designed with built-in alignment openings that directly receive precision alignment elements, making the alignment system self-contained and eliminating the need for additional complex alignment components.
Data Source
AI summary
A method of aligning an OLED substrate with a shadow mask includes forming a shadow mask with at least three spaced alignment openings, providing a precision alignment element into each of the alignment openings, and positioning the OLED substrate so that the edges of the OLED substrate engage the precision alignment elements and thereby align the shadow mask with the OLED substrate.