OLED Shadow Mask Asymmetric Tapered Openings
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Solution Overview
Problem
Existing OLED panel manufacturing by evaporation faces challenges with large sub-pixel size and low aperture ratio, making it difficult to meet requirements for small-sized, high-resolution OLED panels.
Innovation Solution
A semiconductor integrated manufacturing process is used to create a shadow mask with a grid film layer and recessed semiconductor substrate, where the openings have a greater upper portion width than lower portion width, allowing for precise control of evaporation patterns and reducing shadow effects during the evaporation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metal shadow mask with traditional openings is used for OLED evaporation, then the manufacturing process is simple, but the sub-pixel size is large and the aperture ratio is low
Solution Approach 1:
The patent applies asymmetry by designing openings with different widths at the top and bottom surfaces, creating a tapered structure that allows precise control of sub-pixel dimensions while maximizing the aperture ratio. The asymmetric opening geometry enables the evaporation material to form smaller, more precise sub-pixels compared to traditional symmetric openings.
Solution Approach 2:
The patent transitions from a two-dimensional planar opening structure to a three-dimensional tapered structure by varying the opening width through the thickness of the shadow mask. This dimensional change allows the opening to have different effective widths at different depths, enabling simultaneous optimization of sub-pixel size control and aperture ratio.
2Manufacturing precision
If traditional shadow mask openings are used, then the mask structure is simple, but the positional accuracy of light-emitting units is insufficient
Solution Approach 1:
The asymmetric opening design with different top and bottom widths provides enhanced positional accuracy by creating a unique evaporation pattern that precisely defines the light-emitting unit location. The tapered geometry acts as a self-aligning feature that improves positioning precision without requiring additional alignment mechanisms.
Solution Approach 2:
The patent applies local quality by giving different dimensions to different parts of the same opening structure. The top width and bottom width of each opening are independently optimized to achieve specific positional accuracy requirements for the light-emitting units, allowing localized control of evaporation material deposition.
3Manufacturing precision
If conventional evaporation patterns are used, then the process is straightforward, but the morphology of light-emitting units is poor
Solution Approach 1:
The asymmetric tapered opening structure inherently guides the evaporation material to form light-emitting units with superior morphology. The gradual width change through the mask thickness creates a controlled deposition profile that produces well-defined, uniform light-emitting structures without requiring complex post-processing or additional manufacturing steps.
Solution Approach 2:
The shadow mask is pre-formed with the asymmetric tapered opening structure before the evaporation process. This preliminary structuring of the mask ensures that the evaporation material automatically deposits in the desired pattern, pre-determining the morphology of the light-emitting units and eliminating the need for complex real-time process control.
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 enables the formation of small-sized light-emitting units with improved morphology and increased aperture ratio, enhancing the positional accuracy and brightness of OLED panels.
Implementation Method 1
the gaseous light-emitting material generated by an evaporation source 11 diffusing onto the base plate 12 through a number of openings 15 in the metal shadow mask 13
Implementation Method 2
the gaseous light-emitting material generated by an evaporation source 11
Data Source
AI summary
A shadow mask used for OLED evaporation and a manufacturing method therefor, and an OLED panel manufacturing method. The shadow mask used for OLED evaporation includes: a semiconductor substrate including a front surface and a back surface opposite thereto, a recess penetrating the front surface and the back surface being provided in the semiconductor substrate; and a grid film layer provided on the front surface of the semiconductor substrate. A number of openings arranged in an array are provided in the grid film layer. Each of the openings has an upper portion and a lower portion. A width of the upper portion is greater than a width of the lower portion. The recess exposes the number of openings in the grid film layer and the grid film layer between adjacent openings.