Metal Mask Substrate Surface Roughness Control
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Solution Overview
Problem
Metal mask substrates face issues with resist layer adhesion, leading to uneven thickness and peeling, especially when using dry film resists, which affects the accuracy and mechanical strength of the metal masks used in organic electroluminescent devices.
Innovation Solution
A metal mask substrate with a three-dimensional surface roughness of less than or equal to 0.11 μm and 3.17 μm is developed, featuring a surface made of Invar and a polyimide layer, enhancing adhesion between the resist and the substrate, and incorporating through-holes with controlled dimensions to improve etching accuracy and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dry film resist is used to form the resist layer, then the thickness uniformity of the resist layer is improved, but the adhesion between the resist layer and the metal mask substrate deteriorates
Solution Approach 1:
The invention applies different surface roughness characteristics to different regions of the metal mask substrate. Specifically, the obverse surface (where the resist is applied) is maintained with low roughness (Sa≤0.11μm, Sz≤3.17μm) to ensure good adhesion, while the reverse surface may have different characteristics. This localized differentiation resolves the contradiction by optimizing each surface for its specific function.
Solution Approach 2:
The invention changes the surface roughness parameters of the metal mask substrate to resolve the adhesion problem. By controlling the obverse surface roughness within specific ranges (Sa≤0.11μm, Sz≤3.17μm), the substrate provides optimal adhesion for dry film resist while maintaining the thickness uniformity benefits of dry film processing.
2Reliability
If the surface roughness of the metal mask substrate is increased to improve adhesion, then the adhesion between the resist and substrate is improved, but the shape accuracy of the metal mask deteriorates
Solution Approach 1:
The invention differentiates between the functional requirements of different surfaces. The obverse surface is optimized for adhesion with controlled roughness (Sa≤0.11μm, Sz≤3.17μm), while allowing the reverse surface to have different characteristics. This local optimization resolves the contradiction by providing sufficient adhesion without compromising the overall shape accuracy needed for mask functionality.
Solution Approach 2:
The invention creates a composite structure combining the metal mask substrate with the resist layer, where the substrate's controlled surface properties enable optimal bonding. The specific roughness control creates an interface that provides both adhesion and shape fidelity, resolving the contradiction between these two requirements.
Data Source
AI summary
A metal mask substrate includes a metal obverse surface configured such that a resist is placed on the obverse surface. The obverse surface has a three-dimensional surface roughness Sa of less than or equal to 0.11 μm. The obverse surface also has a three-dimensional surface roughness Sz of less than or equal to 3.17 μm.