Liquid-Retaining Rollers for Uniform Silicon Wafer Coating
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Solution Overview
Problem
Existing roller coating devices for silicon wafers in crystalline silicon solar cells result in non-uniform liquid material distribution due to open ends of the rollers, leading to uneven coating thickness and pressure application, which affects the performance of the final solar cells.
Innovation Solution
Implementing a liquid retaining structure with annular folded edges or recessed grooves and raised rings at the ends of the liquid coating and taking rollers to prevent material leakage and using trapezoidal grooves to measure pressure on the wafer, ensuring uniform coating thickness and pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the liquid taking roller and liquid coating roller have open structures at two ends, then the liquid material can be supplied to the rollers, but the liquid material flows out from the two ends resulting in non-uniform thickness
Solution Approach 1:
The roller surface is segmented into a central coating region and two end regions. The liquid retaining structure (raised rings) divides the roller into functional zones: the central zone receives liquid material, while the end zones are blocked by the raised rings to prevent material loss. This segmentation allows the roller to maintain uniform liquid material distribution across its surface.
Solution Approach 2:
The liquid retaining structure (raised rings) is applied locally at the end regions of the rollers, while the central region remains open for liquid material supply. This local modification creates different functional properties in different zones: the ends are blocked to prevent leakage, while the center remains accessible for material delivery, achieving uniform coating without restricting overall material supply.
2Adaptability or versatility
If the liquid coating roller is made of flexible material, then the roller can adapt to the silicon wafer surface, but the pressure applied cannot be directly measured by a pressure sensor
Solution Approach 1:
The liquid retaining structure (raised rings) serves as an intermediary element that transfers the pressure applied by the flexible liquid coating roller to the rigid liquid taking roller. Since the liquid taking roller has a rigid structure, its pressure can be accurately measured by pressure sensors, thereby indirectly measuring the pressure applied by the flexible roller without requiring direct contact between the sensor and the flexible material.
3Productivity
If the liquid coating roller applies pressure to the silicon wafer, then the coating process works, but the pressure is not uniform due to liquid material distribution issues
Solution Approach 1:
The roller system is segmented into functional zones using the liquid retaining structure. The central zone maintains uniform liquid material distribution, which ensures uniform pressure application during coating. The end zones are blocked by raised rings to prevent material loss, ensuring that the pressure applied across the entire roller surface remains consistent and uniform.
Data Source
AI summary
The present disclosure provides a method for roller-coating a liquid material, including roller-coating the liquid material on a silicon wafer with a liquid coating roller, and controlling a thickness of the liquid material carried on the liquid coating roller with a liquid taking roller, where a liquid retaining structure is provided at two ends of the liquid coating roller and/or two ends of the liquid taking roller, and the liquid retaining structure is configured to prevent the liquid material from flowing out from the two ends of the liquid coating roller and the two ends of the liquid taking roller.