Mask Curl Control for OLED Pattern Precision
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Solution Overview
Problem
Existing mask technologies for organic light-emitting display devices face challenges in reducing the shadow phenomenon and side lifting issues due to improper curl values and material compositions, leading to suboptimal pattern formation and display quality.
Innovation Solution
A mask with a body containing nickel and iron, featuring specific welding regions and a pattern region with controlled thickness and curl values, is designed to be attached to a mask frame with a tensile force, optimizing the curl value from 1,000 μm to 4,000 μm before stretching to 0 μm to 400 μm, thereby reducing shadow phenomena and improving pattern precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mask is made with conventional material composition and structure, then the manufacturing process is simple, but shadow phenomenon and side lifting occur due to improper curl values
Solution Approach 1:
The mask body is designed with non-uniform thickness distribution, featuring thicker welding regions at the ends and thinner pattern regions in the middle. This local variation in thickness allows different regions to serve different functions: the thicker welding regions provide structural support and control curl, while the thinner pattern regions enable precise pattern formation, thereby resolving the contradiction between pattern quality and structural simplicity
Solution Approach 2:
The mask employs a composite material composition containing nickel (35-40 wt%) and iron (60-65 wt%), which provides optimized mechanical properties including controlled curl value (1,000-4,000 μm) and appropriate flexibility. This specific composite formulation enables the mask to maintain reliability during deposition while avoiding shadow phenomenon and side lifting, without requiring overly complex structural modifications
2Stability of the object's composition
If the mask thickness is increased to reduce curl, then structural stability improves, but pattern precision deteriorates due to excessive thickness in pattern regions
Solution Approach 1:
The mask implements spatially varying thickness: welding regions have thickness of 6-40 μm (providing stability), while pattern regions have thickness of 6-10 μm (enabling precision). This local differentiation allows the mask to simultaneously achieve structural stability for curl control and manufacturing precision for pattern formation, resolving the contradiction between these two requirements
3Ease of manufacture
If the mask is attached to the mask frame without stretching, then the attachment process is simple, but shadow phenomenon occurs due to high curl value
Solution Approach 1:
The mask is pre-stretched in the length direction (by 0.4-6.0 Kgf tensile force) before attachment to the mask frame. This preliminary stretching action reduces the curl value from 1,000-4,000 μm to 0-400 μm, ensuring that when the mask is attached, it maintains proper contact with the substrate during deposition, thereby preventing shadow phenomenon while keeping the overall process manageable
Data Source
AI summary
A mask and a method of manufacturing a mask assembly, the mask including a body, and the body including one end and another end facing each other in a length direction and having a first surface and a second surface facing each other in a thickness direction; and a pattern region between the one end and the other end, the pattern region including a plurality of pattern holes and a plurality of ribs between the plurality of pattern holes, wherein a curl value of the mask, which is defined as a shortest distance from a plane tangent to a center of the body to the one end or the other end of the body, is 1,000 μm to 4,000 μm.