Non-Contact Edge Coating for Solar Cells Using UV Curing
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Solution Overview
Problem
Conventional edge coating methods for solar cell substrates are costly due to the use of thermal ink and large drying ovens, and they can cause stress and reliability issues with direct mechanical contact and exposure to high temperatures, affecting previous processing steps.
Innovation Solution
A non-contact edge coating apparatus that uses a roller with a recessed groove to apply coating material to the edge of the solar cell substrate without physical contact, employing hot melt ink or UV curable plating resist, and a control system to maintain a consistent distance and rotate the substrate for uniform coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal ink and large drying ovens are used for edge coating, then coating can be applied to the substrate edge, but capital investment costs increase and the process occupies large space
Solution Approach 1:
The patent replaces the thermal oven curing system with a UV LED curing system. Instead of using thermal energy to dry and cure the coating material, the invention uses UV LED light sources that emit specific wavelengths to initiate photopolymerization of UV-curable edge coat materials. This substitution eliminates the need for large, expensive drying ovens while maintaining effective coating curing, directly addressing the capital investment and footprint issues.
Solution Approach 2:
The patent changes the curing parameter from thermal energy (heat) to optical energy (UV light). By switching from thermal ink requiring high-temperature oven drying to UV curable plating resist that cures under UV LED illumination, the system achieves the same coating function with dramatically reduced equipment requirements and capital investment.
2Ease of manufacture
If direct mechanical contact with the substrate is used for coating application, then coating material can be applied to the edge, but stress is applied to the substrate causing reliability issues
Solution Approach 1:
The patent introduces an air bearing as an intermediary between the coating applicator and the substrate. The air bearing creates a thin film of air that allows the applicator to maintain precise proximity to the substrate edge without direct mechanical contact. This intermediary layer enables coating material application while eliminating stress and potential damage to the fragile substrate, particularly important for thin solar cell wafers.
3Reliability
If thermal oven is used for curing coating material, then coating can be cured effectively, but materials deposited on wafer surface in previous processing steps are affected by exposure to oven temperature
Solution Approach 1:
The patent substitutes thermal curing with UV LED optical curing. Instead of exposing the entire wafer and previously deposited materials to high oven temperatures, UV LED lights are directed specifically at the edge coating area. This localized optical curing achieves effective coating hardening while leaving previously deposited materials on the wafer surface unaffected by excessive heat exposure.
Solution Approach 2:
The patent applies curing energy locally only where needed. UV LED light sources are positioned to illuminate specifically the edge coating region, providing localized curing without subjecting the entire wafer or previously processed areas to high temperatures. This selective application of curing energy protects temperature-sensitive materials while ensuring effective edge coat curing.
4Productivity
If conventional contact roller method is used for edge coating, then coating material can be applied to the substrate edge, but the process lacks precision and reliability
Solution Approach 1:
The patent incorporates feedback control through sensors that detect the position and orientation of the substrate edge in real-time. The system uses this feedback information to dynamically adjust the position of the UV LED light sources and coating applicator, maintaining optimal alignment and distance from the substrate edge. This closed-loop control system ensures high precision coating application while maintaining efficient production rates.
Solution Approach 2:
The patent replaces mechanical contact-based coating application with a non-contact UV LED curing system. Instead of relying on physical roller contact that can vary in pressure and alignment, the system uses precisely positioned UV LED arrays that can be accurately controlled and adjusted, achieving superior coating precision while maintaining high productivity through automated positioning systems.
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
This method reduces capital investment costs, minimizes stress on the substrate, and improves reliability by avoiding direct contact and high-temperature curing, allowing for efficient and precise edge coating of solar cell substrates with various coating materials.
Implementation Method 1
UV curable plating resist
Data Source
AI summary
A non-contact edge coating apparatus includes an applicator for applying a coating material on an edge of a solar cell substrate and a control system configured to drive the applicator. The control system may drive the applicator along an axis to maintain a distance with an edge of the substrate as the substrate is rotated to have the edge coated with a coating material. The applicator may include a recessed portion into which the edge of the substrate is received for edge coating. For example, the applicator may be a roller with a groove. Coating material may be introduced into the groove for application onto the edge of the substrate. A variety of coating materials may be employed with the apparatus including hot melt ink and UV curable plating resist.