Deposition Mask Strength via Composite Plating
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Solution Overview
Problem
Deposition masks used in organic EL display devices face challenges with deformation and breakage during ultrasonic cleaning due to reduced strength and cavitation, especially when trying to increase pixel density and aperture ratio.
Innovation Solution
A deposition mask with a mask body that satisfies specific indentation elastic modulus and yield strength criteria, produced by a plating process with a two-layer structure and through-holes formed by precise electrolytic plating, is designed to maintain strength and prevent deformation during cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the aperture ratio of the deposition mask is increased to improve pixel density, then the manufacturing precision and definition are improved, but the strength of the mask body is reduced making it susceptible to deformation during ultrasonic cleaning
Solution Approach 1:
The deposition mask employs a composite structure consisting of a mask body made from a specific metal plate material combined with a plated layer formed through electrolytic plating. This composite construction allows the mask to achieve high aperture ratios for improved pixel density while the plated layer reinforces the mask body to prevent deformation during ultrasonic cleaning.
Solution Approach 2:
The invention specifies precise parameter ranges for the metal plate material including indentation elastic modulus of 120 GPa or more and yield strength of 800 MPa or more. These parameter changes in material properties enable the mask body to maintain sufficient strength even when the aperture ratio is increased for higher pixel density requirements.
2Manufacturing precision
If the thickness of the deposition mask is decreased to improve pixel density reproduction, then the manufacturing precision is improved, but the mask becomes more susceptible to deformation and breakage during ultrasonic cleaning
Solution Approach 1:
The mask utilizes a composite structure where a thin mask body (5 μm to 50 μm thickness) is combined with a plated layer. This composite design allows the mask to be thin enough for high pixel density reproduction while the plated layer provides reinforcement to prevent deformation and breakage during ultrasonic cleaning, thereby maintaining reliability.
Solution Approach 2:
The invention establishes specific parameter ranges for mask thickness (5 μm to 50 μm) combined with minimum material properties (indentation elastic modulus of 120 GPa, yield strength of 800 MPa). These parameter changes enable the mask to achieve the required thinness for high-definition pixel density reproduction while maintaining sufficient mechanical strength and reliability during cleaning operations.
3Productivity
If ultrasonic cleaning is performed to remove adhering deposition material, then the utilization efficiency is improved, but the mask body deforms due to ultrasonic waves forming recesses
Solution Approach 1:
The plated layer in the composite structure serves as a protective reinforcement on the mask body surface. This composite construction allows the mask to withstand ultrasonic cleaning waves without deforming, enabling repeated cleaning cycles to maintain utilization efficiency while preserving the original mask body shape and through-hole patterns.
Solution Approach 2:
The plated layer acts as a pre-applied protective cushion on the mask body surface before ultrasonic cleaning occurs. This beforehand reinforcement prevents the ultrasonic waves from directly impacting and deforming the mask body, allowing safe and effective cleaning to maintain utilization efficiency without shape degradation.
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 suppresses deformation and breakage during ultrasonic cleaning, enhancing the durability and utilization efficiency of the deposition mask while maintaining high-definition capabilities.
Implementation Method 1
a plating solution is supplied to the gap of the resist pattern to precipitate a metal layer on the base material by an electrolytic plating process
Implementation Method 2
there is a possibility that both faces of the deposition mask are deformed by ultrasonic waves emitted at the time of cleaning
Implementation Method 3
the deposition mask is likely to be broken due to cavitation generated during the ultrasonic cleaning
Data Source
AI summary
A deposition mask includes a mask body and a through-hole provided in the mask body and through which a deposition material passes when the deposition material is deposited on a deposition target substrate. The mask body satisfies y≥950 and y≥23x−1280 when an indentation elastic modulus is x (GPa) and a 0.2% yield strength is y (MPa). When the mask body satisfies these inequalities, the generation of recesses during ultrasonic cleaning of the mask can be suppressed.