Slit Die Coating Flow Control for Uniform Slurry Films
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Solution Overview
Problem
Existing coating devices prone to slurry separation due to pressure, affecting the quality and uniformity of the coating film, especially when the slurry is returned to the tank for reuse.
Innovation Solution
A coating device with a slit die configuration that includes a first manifold and adjustment units along second flow paths to precisely control the flow distribution of the coating liquid, preventing return to the tank and ensuring uniform film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pressure is applied to the slurry inside the die to maintain coating flow, then the coating film thickness can be controlled, but the slurry separates and quality deteriorates
Solution Approach 1:
The flow path is segmented into multiple second flow paths with individual adjustment units, allowing separate control of coating liquid flow to different regions of the die. This segmentation enables precise flow distribution control without applying excessive pressure to the entire slurry, preventing separation while maintaining coating uniformity.
Solution Approach 2:
Adjustment units are provided at different locations along the second flow paths to locally regulate flow rates. This allows each region of the die to receive the appropriate amount of coating liquid according to its specific requirements, achieving uniform coating thickness without subjecting the slurry to uniform high pressure that would cause separation.
2Productivity
If the slurry is returned to the tank for reuse to improve efficiency, then material utilization increases, but the separated slurry affects coating film quality
Solution Approach 1:
The patent extracts the coating liquid directly from the die without returning it to the tank. By eliminating the return path, separated slurry cannot recontaminate the fresh coating liquid, ensuring consistent coating quality while still achieving efficient material utilization through precise flow control at the point of application.
Solution Approach 2:
The coating liquid is used once and discarded rather than returned for reuse. This approach treats the coating liquid as a single-use resource, eliminating the quality problems associated with returning separated slurry to the tank while maintaining high productivity through optimized flow distribution.
3Manufacturing precision
If multiple adjustment units are added to control flow distribution, then coating uniformity improves, but device complexity increases
Solution Approach 1:
The flow path is divided into multiple second flow paths with adjustment units positioned along them. This segmentation strategy achieves precise flow control by breaking down the complex adjustment task into manageable regional controls, making the system more controllable despite the added components.
Solution Approach 2:
Adjustment units are arranged along the length of the second flow paths rather than only at the end. This spatial arrangement in one dimension (along the flow path) simplifies the overall configuration compared to having multiple complex adjustment mechanisms at a single point, achieving flow distribution control through a linear arrangement of simpler components.
Data Source
AI summary
A coating device comprises a die with a slit that is longer in a width direction and discharges a coating liquid to form a coating film on a substrate, a first flow path that supplies the coating liquid toward the die, a first manifold that is linked to the first flow path and holds the coating liquid that flows in from the first flow path, a plurality of second flow paths that are linked to the first manifold, a second manifold that is linked to the second flow paths and the slit, is longer in the width direction, and holds the coating liquid that flows in from the second flow paths, and an adjustment unit that is provided along at least one of the second flow paths and adjusts a flow of the coating liquid flowing through the at least one of the second flow paths.