Mask Frame Assembly with Howling Sticks for OLED Evaporation
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Solution Overview
Problem
The existing mask frame assemblies for OLED display panels face issues with sagging of fine metal mask plates due to gravity, leading to poor contact with the substrate during evaporation, which results in lateral Mura defects and reduced production yield.
Innovation Solution
A mask frame assembly with a hollow frame and howling sticks that support the fine metal mask plate, where the howling sticks are positioned in the invalid mask area and have a groove deep enough to counteract sagging, ensuring stable positioning and reduced deformation, and the assembly is integrated with a magnetic spacer for precise substrate contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fine metal mask plate is welded on the frame without support structures, then the manufacturing process is simple, but the mask plate sags due to gravity causing poor contact with substrate
Solution Approach 1:
The support structure is segmented into multiple howling sticks distributed across the mask plate, with each stick providing localized support at specific positions. This segmentation allows the mask plate to maintain flatness without requiring a complete rigid backing structure, thus balancing manufacturing simplicity with contact precision.
Solution Approach 2:
The howling sticks act as intermediary support elements between the mask plate and the frame. These sticks provide the necessary mechanical support to counteract gravity-induced sagging, ensuring the mask plate maintains proper contact with the substrate during evaporation without direct welding of the mask plate to the frame.
2Manufacturing precision
If howling sticks are added to support the mask plate, then contact precision with substrate is improved, but the device structure becomes more complex
Solution Approach 1:
Instead of providing uniform support across the entire mask plate, the howling sticks are strategically positioned only at critical locations where sagging occurs. This local quality approach provides necessary support precision while minimizing the overall structural complexity and number of components required.
Solution Approach 2:
The howling sticks provide slightly more support than the minimum theoretical requirement, ensuring adequate contact pressure between the mask plate and substrate. This partial excessive action guarantees precision without requiring a fully rigid or overly complex support structure.
3Area of stationary object
If the mask plate is made larger to cover more area, then the evaporation coverage is improved, but the sagging deformation increases
Solution Approach 1:
The support structure is divided into multiple howling sticks distributed across the larger mask plate area. This segmentation allows each stick to support a specific region, collectively maintaining the overall flatness of the expanded mask plate while providing sufficient evaporation coverage.
Solution Approach 2:
The support problem is solved by adding a vertical dimension consideration - the howling sticks provide upward support force in the vertical dimension to counteract gravity, allowing the mask plate to extend in the horizontal dimension without proportionally increasing sagging deformation.
4Speed
If the mask plate is made thinner to reduce weight, then the response speed is improved, but the structural stability decreases
Solution Approach 1:
The howling sticks serve as intermediary support structures that compensate for the reduced structural stability of thinner mask plates. By providing external support at critical points, the thin mask plate maintains its lightweight advantage and fast response characteristics while achieving the necessary structural stability through the support system.
Data Source
AI summary
A mask frame assembly, including: a hollow frame, which is provided with a hollow area; and a first howling stick, disposed across the hollow area of the hollow frame in a first direction; wherein the mask frame assembly is configured to support a fine metal mask plate which includes a mask pattern area and an invalid mask area surrounding the mask pattern area; in a state of the fine metal mask plate being supported by the mask frame assembly, opposite ends of the fine metal mask plate are fixed on the hollow frame in a second direction; the mask pattern area of the fine metal mask plate is disposed in the hollow area of the hollow frame; and a projection of the first howling stick on the fine metal mask plate is in the invalid mask area. An evaporation device is also disclosed.