Clad Mask Support Structure for Thermal Deformation Control
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Solution Overview
Problem
The deformation of mask support structures due to thermal expansion issues leads to reduced deposition reliability in the formation of emission layers in display devices, affecting the accuracy and consistency of pixel formation.
Innovation Solution
A mask assembly with a frame, support portions, and a mask, where the support portions are designed as a clad structure with a central layer and outer layers having different thermal expansion coefficients, and the support portions are arranged in a specific pattern to minimize shape deformation and enhance deposition reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple support structure is used for the mask, then the device complexity is reduced, but the support portion deforms due to thermal expansion, reducing deposition reliability
Solution Approach 1:
The support portion is constructed as a composite structure with a central layer and two outer layers made of different materials. The central layer has a first thermal expansion coefficient, while the outer layers have a second thermal expansion coefficient that is smaller than the first. This composite material approach allows the support portion to maintain dimensional stability during thermal cycles while avoiding the need for complex active compensation mechanisms.
Solution Approach 2:
The invention changes the thermal expansion parameter by selecting materials with specific thermal expansion coefficients for the central and outer layers. The central layer uses a material with a higher thermal expansion coefficient (such as Invar), while the outer layers use materials with lower thermal expansion coefficients. This parameter selection enables the support structure to accommodate thermal expansion differently across layers, preventing overall deformation.
2Shape
If a single-material support portion is used, then the manufacturing process is simplified, but thermal expansion causes shape deformation
Solution Approach 1:
The support portion employs a composite structure consisting of a central layer and two outer layers made of different materials with different thermal expansion coefficients. This composite construction inherently provides shape stability during thermal cycles, as the differential expansion between layers creates internal stresses that counteract overall deformation, eliminating the need for complex shape compensation design.
Solution Approach 2:
The support portion is segmented into multiple functional layers: a central layer and two outer layers. Each layer serves a specific function - the central layer provides structural support and magnetic properties, while the outer layers provide thermal stability. This segmentation allows each layer to be optimized for its specific function while working together to achieve overall shape stability.
3Reliability
If the outer layers have the same thermal expansion coefficient as the central layer, then the manufacturing is easier, but thermal expansion deformation occurs
Solution Approach 1:
The support portion is constructed as a composite structure with a central layer and two outer layers made of different materials. The central layer has a first thermal expansion coefficient, while the outer layers have a second thermal expansion coefficient that is smaller than the first. This composite material approach allows the support portion to maintain dimensional stability during thermal cycles while avoiding the need for complex active compensation mechanisms.
Solution Approach 2:
The invention explicitly utilizes thermal expansion principles by selecting materials with different thermal expansion coefficients for different layers. The outer layers have a smaller thermal expansion coefficient than the central layer, causing them to expand less during heating. This differential expansion creates internal stress distribution that prevents overall shape deformation of the support portion, directly addressing the thermal expansion issue.
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 effectively reduces shape deformation of the support portions, thereby improving the deposition reliability and consistency of the emission layer formation, ensuring better pixel formation accuracy and device performance.
Implementation Method 1
a thermal expansion coefficient of the central layer may be different from a thermal expansion coefficient of the first outer layer
Data Source
AI summary
A mask assembly includes a frame in which an opening is defined, a support portion on the frame and overlapping with the opening, and a mask on the support portion and covering at least a portion of the opening. The support portion may include a central layer, a first outer layer on a first surface of the central layer, and a second outer layer on a second surface of the central layer, the second surface being opposite to the first surface.