OLED Deposition Mask Surface Control for 500 PPI Pixel Patterning
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Solution Overview
Problem
Current deposition masks face challenges in achieving high-resolution patterns above 500 PPI due to surface roughness deviations in the longitudinal and lateral directions, leading to non-uniform hole diameters and adhesion issues, which result in deposition failures and positional inaccuracies during OLED pixel deposition.
Innovation Solution
A metallic deposition mask with controlled surface roughness and inclination angles, where the metal plate's surface is treated to have uniform roughness in all directions, ensuring consistent adhesion and rigidity, and featuring a unique through-hole design with large and small surface holes to secure precise pattern deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional mask with planar surface and right-angled corners is used for OLED pixel deposition, then the mask structure is simple and easy to manufacture, but the deposited metal layers exhibit poor uniformity and rough surfaces due to line-of-sight deposition limitations
Solution Approach 1:
The mask surface is designed with a specific curvature radius (R1 for first surface, R2 for second surface) to enable angled deposition of metal layers. This curved geometry allows metal atoms to deposit at various angles across the substrate, improving layer uniformity and reducing surface roughness compared to conventional planar masks with right-angled corners
2Manufacturing precision
If multiple deposition processes are performed sequentially for different metal layers, then each layer can be deposited with controlled parameters, but the total deposition time and process complexity increase significantly
Solution Approach 1:
The mask design enables simultaneous deposition of multiple metal layers (EMIL, EML, ETL) in a single deposition process. The curved surfaces and apertures are positioned and sized to allow different metal materials to deposit at different locations and angles during one deposition run, eliminating the need for multiple sequential deposition processes
3Manufacturing precision
If the mask aperture size is reduced to achieve finer pixel patterns, then the OLED resolution improves, but the deposited metal layer becomes thinner and more prone to discontinuities
Solution Approach 1:
The mask design incorporates different aperture sizes (first aperture and second aperture with different dimensions) and positions them at specific locations on the curved mask surface. This allows optimization of aperture size for each metal layer deposition, ensuring sufficient metal accumulation and continuous layer formation even for fine pixel patterns, while maintaining high resolution
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 uniform and precise deposition of high-resolution OLED pixel patterns, minimizing deposition failures and ensuring accurate positioning, thereby improving the efficiency and consistency of the deposition process.
Implementation Method 1
Metal layers are deposited on a substrate using a line-of-sight deposition method such as vacuum evaporation or sputtering
Data Source
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AI summary
A metallic material deposition mask for OLED pixel deposition according to an embodiment of the present invention includes a deposition region for forming a deposition pattern and a non-deposition region other than the deposition region. The deposition region includes a plurality of effective portions spaced apart in the longitudinal direction and non-effective portions other than the effective portions. The effective portions include: a plurality of small-area holes formed on one surface; a plurality of large-area holes formed on the reverse surface on the opposite side to the one surface; through-holes through which the small-area holes and large-area holes communicate; and island parts between the plurality of through-holes, wherein the through-holes have a dimeter of no greater than 33 um, the distance between the centers of two neighboring through-holes among the through-holes is no greater than 48 um, which corresponds to a resolution of 500 PPI, the inclination angle of the large-area holes with respect to the reverse surface is 40 degrees to 55 degrees, the average center-line average surface roughness of the non-deposition region in the longitudinal direction and average center-line average surface roughness of the non-deposition region in the widthwise direction are 0.1 um to 0.3 um, the average 10-point average surface roughness (Rz) of the non-deposition region in the longitudinal direction and average 10-point average surface roughness of the non-deposition region in the widthwise direction are 0.5 um to 2.0 um, the deviation of the average center-line average surface roughness value in the longitudinal direction with respect to the average center-line average surface roughness in the widthwise direction is less than 50%, and the deviation of the average 10-point average surface roughness value in the longitudinal direction with respect to the average 10-point average surface roughness in the widthwise direction is less than 50%.