Vapor Deposition Mask Alignment Using Matched Thermal Expansion
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Solution Overview
Problem
In the manufacturing of high-definition organic electroluminescent (EL) display devices, such as those required for smartphones and tablets, the vapor deposition masks face challenges in maintaining accurate alignment and positional accuracy due to differences in thermal expansion coefficients between the mask components and the substrate, leading to misregistration and reduced dimensional accuracy.
Innovation Solution
The use of nickel-containing iron alloys, such as Invar and super Invar materials, for the mask main body, support, and frame, along with alignment marks, ensures that the thermal expansion coefficients match those of the glass substrate, maintaining precise alignment and preventing deformation during high-temperature vapor deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional materials with different thermal expansion coefficients are used for mask components, then manufacturing is easier and cost is lower, but alignment accuracy deteriorates due to misregistration during high-temperature vapor deposition
Solution Approach 1:
The patent changes the thermal expansion parameter of the mask components by selecting nickel-containing iron alloys (Invar, super Invar) with specific compositional ranges. This parameter change ensures that the thermal expansion coefficients of the mask main body, support, and frame match those of the glass substrate, preventing misregistration during high-temperature vapor deposition processes while maintaining manufacturing feasibility
Solution Approach 2:
The patent applies homogeneity by using the same material system (nickel-containing iron alloys) for multiple mask components (mask main body, support, and frame). This ensures uniform thermal expansion characteristics across all mask components and matches the substrate's thermal properties, eliminating differential expansion that would cause alignment errors during heating
2Stability of the object's composition
If the mask structure is reinforced to prevent deformation, then stability improves, but the complexity of manufacturing increases
Solution Approach 1:
The patent changes the material parameter (thermal expansion coefficient) to match between mask components and substrate, which inherently stabilizes the mask structure during thermal processing. By preventing differential expansion, the mask maintains its dimensional stability and prevents deformation without requiring additional reinforcement structures or complex manufacturing procedures
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
This approach enhances the accuracy and stability of the vapor deposition process, ensuring high-definition patterns are achieved without misregistration, thereby improving the quality of the organic EL display devices.
Implementation Method 1
The use of nickel-containing iron alloys, such as Invar and super Invar materials, for the mask main body, support, and frame, along with alignment marks, ensures that the thermal expansion coefficients match those of the glass substrate, maintaining precise alignment and preventing deformation during high-temperature vapor deposition processes
Implementation Method 2
a vapor deposition step of first putting a substrate (an organic EL substrate) for the organic EL display device into a vapor deposition device, then putting a vapor deposition mask into close contact with the organic EL substrate in the vapor deposition device, and finally vapor-depositing an organic material onto the organic EL substrate is conducted
Data Source
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AI summary
A vapor deposition mask includes a mask main body and a support joined to the mask main body. The mask main body has a first alignment mark whereas the support has a second alignment mark. The first alignment mark and the second alignment are provided at such positions as to overlap with each other in plan view, and either one of the alignment marks is larger than the other of the alignment marks.