Invar Metal Plate Flatness Control for Deposition Mask Transport
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Solution Overview
Problem
The manufacturing of deposition masks for organic EL display devices faces challenges due to material adherence issues during the deposition process, leading to reduced dimensional and positional precision, and the metal plates used for these masks often exhibit corrugation and non-uniform deformation, causing transport failures and reduced throughput.
Innovation Solution
A method of manufacturing metal plates with controlled corrugation by rolling and cutting, ensuring specific steepness degree conditions are met, and using an invar alloy to stabilize the metal plates, which allows for the formation of deposition masks with improved transportability and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the metal plate is reduced to lower the height of the through-hole wall surface, then the deposition material adherence to the wall surface is reduced, but the non-uniformity of deformation during rolling increases, causing corrugation and transport failure
Solution Approach 1:
The patent applies parameter changes by carefully controlling the reduction ratio during the rolling process and specifying the thickness range of the metal plate (0.01mm to 0.1mm). By optimizing these parameters, the patent achieves a balance where the thickness is reduced enough to minimize deposition material adherence to wall surfaces, while maintaining uniform deformation to prevent corrugation and ensure stable transport.
2Length of moving object
If the reduction ratio is increased to obtain thinner metal plate, then the thickness of metal plate is reduced, but the non-uniformity degree of deformation during rolling becomes larger, causing edge wave and middle wave corrugation
Solution Approach 1:
The patent controls the reduction ratio parameter during rolling to achieve the desired thickness while maintaining flatness. It specifies that the reduction ratio should be within a controlled range and employs multiple rolling passes with intermediate annealing to distribute deformation uniformly, preventing edge wave and middle wave corrugation even when producing thin plates.
Solution Approach 2:
The patent applies preliminary action by performing intermediate annealing treatment during the rolling process. This preliminary heat treatment restores the metal's ductility and reduces internal stresses before subsequent rolling passes, enabling uniform deformation and preventing corrugation from developing during the thickness reduction process.
3Manufacturing precision
If the thickness of metal plate is reduced to improve deposition precision, then the height of through-hole wall surface is reduced, but the transport stability of metal plate deteriorates due to corrugation
Solution Approach 1:
The patent optimizes the thickness parameter to a specific range (0.01mm to 0.1mm) that provides sufficient flatness for stable transport while being thin enough to minimize deposition material adherence. This parameter optimization ensures both transport reliability and deposition precision are achieved simultaneously.
Solution Approach 2:
The patent performs preliminary annealing treatment before and during the rolling process to maintain the metal plate's flatness and reduce internal stresses. This preliminary action prevents corrugation from developing, ensuring the plate remains stable during transport even at reduced thicknesses.
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 method enables the production of deposition masks with enhanced stability and precision, reducing material adherence issues and improving the efficiency and throughput of the deposition process, resulting in higher quality organic EL display devices.
Implementation Method 1
rolling a base metal to obtain the metal plate
Implementation Method 2
cutting both ends in a width direction of the metal plate over a predetermined range
Implementation Method 3
through-holes are formed by etching the elongated metal plate that is being transported
Implementation Method 4
a deposition mask is firstly brought into tight contact with a substrate for organic EL display device, and then the substrate and the deposition mask in tight contact therewith are put into a deposition apparatus so as to deposit an organic material
Data Source
AI summary
The object of the present invention is to provide a metal plate having an excellent transportability. A maximum value of a steepness degree at a central area in a width direction of the metal plate is not more than 0.4%. In addition, the maximum value of the steepness degree at the central area is not more than a steepness degree at one end side area, and is not more than a steepness degree at the other end side area. Further, a difference between the maximum value of the steepness degree at the one end side area and the maximum value of the steepness degree at the other end side area is not more than 0.4%.