Composite Deposition Mask Structure for Warpage Control
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Solution Overview
Problem
Existing deposition masks for organic light-emitting display devices suffer from warpage and deformation, which can lead to misalignment and damage, affecting the deposition process and resulting in defects in the display panel.
Innovation Solution
A deposition mask design incorporating a first composite layer with a balanced ratio of tensile and compressive layers, where the total sum of their characteristic values is maintained within a specific range (0.5 to 1) to minimize warpage, using materials like silicon nitride and silicon oxide, and optionally additional layers to ensure structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deposition mask is used for organic light-emitting display devices, then the deposition process can be performed, but warpage and deformation occur causing misalignment and damage
Solution Approach 1:
The patent applies composite materials by constructing the mask with multiple layers including a support layer, a first composite layer with tensile and compressive layers, and optionally a second composite layer. Each layer is made of specific materials (e.g., silicon nitride, silicon oxide, molybdenum, aluminum, tungsten) with controlled stress characteristics. This multi-material composite structure allows balancing internal stresses to minimize warpage while maintaining structural integrity for reliable deposition.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the stress values and thicknesses of each layer. The characteristic value (stress × thickness) of tensile layers and compressive layers is balanced within specific ranges. By adjusting these parameters, the overall stress distribution is optimized to prevent warpage and deformation, ensuring the mask maintains its shape during the deposition process.
2Ease of manufacture
If the mask structure is simplified, then manufacturing is easier, but warpage control becomes difficult
Solution Approach 1:
The mask is segmented into multiple functional layers: a support layer providing structural foundation, a first composite layer with balanced tensile and compressive layers for stress control, and optionally a second composite layer for additional stability. This segmentation allows each layer to be optimized independently for its specific function while collectively achieving both manufacturability and warpage control.
Solution Approach 2:
By controlling the characteristic values (stress × thickness) of each layer within specific ranges, the patent achieves deformation control without excessive complexity. The balanced ratio between tensile and compressive layer characteristic values provides a practical design guideline that simplifies manufacturing while ensuring shape stability.
3Manufacturing precision
If the mask maintains structural integrity, then deposition precision is improved, but the mask becomes more complex
Solution Approach 1:
The multi-layer composite structure with specific materials (silicon nitride, silicon oxide, molybdenum, aluminum, tungsten) provides the necessary structural integrity for precise deposition. Each material is selected for its specific stress characteristics and mechanical properties, creating a balanced composite system that maintains shape stability without requiring excessive structural complexity.
Solution Approach 2:
By establishing specific ranges for the characteristic values of tensile and compressive layers, the patent defines clear design parameters that ensure deposition precision. This parameter-based approach provides a systematic method to achieve structural integrity while controlling mask complexity through quantifiable design criteria.
Data Source
AI summary
A deposition mask for depositing a pattern on a display panel includes an in-cell area and an out-cell area around the in-cell area, a first composite layer in the in-cell area and the out-cell area, and a support layer on a lower surface of the first composite layer in the out-cell area. The first composite layer includes one or more tensile layers including a tensile material that has a stress greater than 0, and one or more compressive layers including a compressive material that has a stress less than 0. Each layer has a characteristic value measured by multiplying a stress of each layer by a corresponding thickness of each layer. A ratio between a sum of the characteristic values of the one or more tensile layers and a sum of characteristic values of the one or more compressive layers is within a range of about 0.5 to about 1.