Double Printing Screen Stencil for Solar Panel Electrode Tensile Force
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Solution Overview
Problem
The existing double screen stencil printing method for solar cells results in insufficient tensile force of the positive electrode due to insufficient busbar height, leading to unqualified electrodes and increased production costs when attempting to enhance tensile force.
Innovation Solution
A double printing method using a first and second screen stencil, where the first stencil includes equally spaced fingers and bottom electrodes at busbar positions, and the second stencil includes corresponding aligning points to enhance busbar height during secondary printing, improving tensile force without significantly increasing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the busbar height is increased by adjusting screen stencil parameters, then the tensile force of the positive electrode is improved, but the consumption of silver paste increases and production costs go up
Solution Approach 1:
The printing process is divided into two separate screen stencils: the first screen stencil prints only the fingers, and the second screen stencil prints only the busbars. This segmentation allows each stencil to be optimized independently, with the second stencil specifically designed to deposit additional silver paste to increase busbar height and tensile force without unnecessarily increasing overall silver paste consumption.
Solution Approach 2:
The second screen stencil is designed to print busbars with specific local characteristics (higher height and increased silver paste deposition) only where needed, while the first screen stencil handles the fingers with different requirements. This local quality approach ensures that increased silver paste consumption is concentrated only in the busbar regions where tensile force improvement is needed, rather than uniformly across the entire electrode.
2Strength
If the busbar height is increased to ensure tensile force, then the tensile force of the positive electrode is improved, but the production cost increases
Solution Approach 1:
By segmenting the printing process into two specialized stencils, the invention enables precise control over where and how much silver paste is deposited. The second stencil is specifically optimized to increase busbar height only in the critical busbar regions, avoiding wasteful deposition in other areas and thereby controlling production costs while achieving the required tensile force.
Solution Approach 2:
The invention changes the printing parameters by using two different screen stencils with different mesh counts, opening ratios, and design characteristics. The second stencil is specifically designed with parameters optimized for depositing thicker silver paste to increase busbar height, allowing cost-effective achievement of tensile force requirements through parameter optimization rather than blanket increases in material consumption.
3Strength
If silver paste formula is modified to have high tensile force and strong corrosivity, then the tensile force can be improved, but the efficiency of solar cell decreases
Solution Approach 1:
The invention applies local quality by using the second screen stencil to deposit additional silver paste with enhanced tensile force properties specifically in the busbar regions where mechanical strength is critical. This localized application allows the use of modified silver paste formula with stronger corrosivity only where needed for tensile force, while minimizing the impact on overall solar cell efficiency by limiting the modified paste application to busbar areas rather than the entire electrode surface.
Data Source
AI summary
A double printing screen stencil includes a first screen stencil and a second screen stencil. The first screen stencil pattern includes equally spaced fingers. A plurality of bottom electrodes are arranged at the position of the busbar intersecting with the fingers. The first screen stencil pattern further includes at least two aligning points. The second screen stencil pattern includes equally spaced fingers, busbars intersecting with the fingers, aligning points corresponding to the aligning points in the first screen stencil pattern. The fingers are corresponding to those of the first screen stencil and the spacing of the fingers is the same as that of the first screen stencil. When the screen stencil is used in printing, the bottom electrodes are printed at the position of the busbar while the fingers are printed during the primary printing, so as to increase the height of busbar during, the secondary printing.