Solar Cell Screen Printing for Wet-On-Wet Conductive Patterns
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Solution Overview
Problem
The existing solar cell manufacturing processes are costly and inefficient due to the need for multiple processing stations and separate curing steps for conductive patterns, which decreases overall yield and increases the footprint and operational costs of processing lines.
Innovation Solution
A method and apparatus for depositing conductive patterns on solar cell substrates using a screen with a varying vertical profile, allowing for the printing of a second conductive pattern onto a still-wet first pattern without contact, followed by joint curing, reducing the number of processing stations and curing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple separate deposition stations are used to deposit different conductive patterns, then each pattern can be deposited with dedicated equipment, but the footprint and cost of the processing line increases
Solution Approach 1:
The patent combines multiple deposition functions into a single screen printing station. The screen is designed with multiple opening patterns that enable deposition of different conductive patterns (fingers, busbars, rear contacts) in one operation, eliminating the need for multiple separate deposition stations and reducing the processing line footprint.
Solution Approach 2:
The screen printing apparatus is designed with universal functionality to deposit various conductive patterns through a single screen. The screen can be configured with different opening patterns for different patterns, and the varying vertical profile allows the same screen to handle wet-on-wet deposition of multiple patterns without requiring separate dedicated equipment for each pattern type.
2Manufacturing precision
If multiple curing stations are used to cure conductive patterns sequentially, then each pattern can be cured independently, but the number of processing stations increases and total yield decreases
Solution Approach 1:
The patent merges multiple curing operations into a single curing station. By enabling wet-on-wet deposition where multiple conductive patterns are deposited on the substrate before curing, the system allows one curing station to cure all patterns simultaneously, reducing the number of processing stations from multiple sequential curing stations to a single curing station, thereby improving total yield.
Solution Approach 2:
The patent performs preliminary deposition of multiple conductive patterns on the substrate while the first pattern is still wet, before curing occurs. This preliminary action of depositing all patterns in sequence on the wet substrate enables subsequent single-step curing of all patterns together, eliminating the need for multiple sequential curing stations.
3Device complexity
If a flat screen is used for printing, then the screen structure is simple, but the screen contacts the wet conductive pattern causing deformation
Solution Approach 1:
The patent introduces asymmetry in the screen structure through a varying vertical profile instead of a flat surface. The screen has high portions and low portions at different heights, creating an asymmetric three-dimensional structure that prevents contact between the screen and the wet conductive pattern during printing, thereby preventing pattern deformation while maintaining reasonable structural complexity.
Solution Approach 2:
The patent transitions from a two-dimensional flat screen to a three-dimensional screen with a varying vertical profile. This dimensional change adds height as a new dimension, allowing the screen to be positioned at different heights (high portions elevated above the wet pattern, low portions near the substrate) to avoid contact with the wet conductive pattern while still enabling material transfer through openings.
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 approach enhances efficiency by allowing wet-on-wet deposition, reducing the need for multiple curing stations and processing steps, thereby decreasing costs and footprint while improving yield and handling robustness of the substrate.
Implementation Method 1
transferring a printing material from the screen to the substrate through the set of openings to print a second conductive pattern on the first side of the substrate
Data Source
AI summary
A method of deposition on a substrate used for the manufacture of a solar cell is provided. The method includes depositing a first conductive pattern on a first side of the substrate. The first conductive pattern is one of a plurality of busbars and a plurality of fingers. The method includes providing a screen over the substrate. The screen includes a set of openings. The screen has a bottom side having a varying vertical profile including low portions and high portions. The method includes transferring a printing material from the screen to the substrate through the set of openings to print a second conductive pattern on the first side of the substrate. The second conductive pattern is the other one of the plurality of busbars and the plurality of fingers. During the printing of the second conductive pattern, the first conductive pattern is substantially wet and the screen is disposed over the substrate in a manner such that the high portions are elevated above the first conductive pattern.