Active Solder Electrodes for Solar Cells
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Solution Overview
Problem
Conventional solar cell manufacturing processes are costly due to high-cost conductive pastes, require high-temperature sintering that can damage other material layers, and demand precise temperature control for reliable electrode formation, leading to reduced yield and complexity.
Innovation Solution
The use of an active solder with a soldering alloy mixed with a rare earth element, applied at lower temperatures to form electrodes on solar cell substrates without penetrating the anti-reflection layer, simplifying the process and ensuring reliable electrical connection, and optionally enhanced with electroless or electroplating for increased thickness and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature sintering (450-850°C) is used to form electrodes with conductive pastes, then reliable electrical connection is achieved, but other material layers are damaged or malfunctioned and manufacturing yield is reduced
Solution Approach 1:
The patent changes the temperature parameter from high-temperature sintering (450-850°C) to low-temperature processing (below 450°C). The conductive paste is reformulated with a lower melting point composition that enables electrode formation at reduced temperatures, thereby preventing damage to other material layers while maintaining electrical connection reliability
Solution Approach 2:
The patent uses a composite conductive paste material containing metal particles, glass particles, and organic vehicle specifically designed for low-temperature processing. This composite formulation allows the paste to flow and form reliable electrical connections at lower temperatures without requiring harsh sintering conditions that would damage other layers
2Reliability
If high-temperature sintering is used to ensure complete penetration of conductive paste through anti-reflection layer, then electrical contact with diffusion layer is achieved, but process complexity and time consumption increase
Solution Approach 1:
The patent modifies the temperature parameter to be lower (below 450°C) and adjusts the processing time and paste composition accordingly. The reformulated conductive paste has improved flow characteristics at lower temperatures, enabling adequate penetration through the anti-reflection layer without requiring precise high-temperature control, thus reducing process complexity
3Ease of manufacture
If conventional conductive pastes containing glass microparticles and organic solvents are used, then electrode formation is achieved, but solar cell chips are contaminated and additional cleaning is required
Solution Approach 1:
The patent modifies the composition parameters of the conductive paste by reducing or eliminating organic solvents and adjusting glass particle content. This formulation change enables the paste to form electrodes effectively while minimizing contamination, reducing or eliminating the need for additional cleaning steps
Solution Approach 2:
The patent extracts or removes the harmful organic solvent component from the conventional conductive paste formulation. The remaining inorganic components (metal particles, glass particles) are reformulated to provide adequate flow and bonding properties without the contamination issues caused by organic solvents, thereby eliminating the cleaning step
4Reliability
If silver, aluminum, or aluminum-silver conductive pastes are used for electrodes and conductive wires, then electrical conductivity is achieved, but material cost increases to about 10% of total module cost
Solution Approach 1:
The patent employs a composite conductive paste containing a mixture of metal particles (including but not limited to silver, aluminum, or their alloys) combined with glass particles and organic vehicle. This composite formulation achieves the required electrical conductivity through the metal network while the glass and organic components facilitate processing and bonding, thereby maintaining conductivity performance while reducing overall material cost
Solution Approach 2:
The patent applies different metal particle compositions and concentrations in different regions of the conductive paste formulation. By optimizing the local metal content and distribution within the paste, adequate electrical conductivity is achieved in critical areas while reducing overall precious metal content, thus lowering material cost while maintaining performance
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 reduces material costs, simplifies the manufacturing process, enhances the reliability of electrical connections, and increases the yield of solar cell production while maintaining high conversion efficiency.
Implementation Method 1
firstly melting the active solder at a temperature lower than 450° C.
Implementation Method 2
then applying the molten active solder on the solar cell substrate
Implementation Method 3
cooling to solidify the active solder, so as to form an electrode pattern
Implementation Method 4
providing an active solder having at least one type of soldering alloy mixed with 6 wt % or less of at least one type of active component
Data Source
AI summary
Electrodes of a solar cell formed by an active solder and a method therefor are provided. The method includes steps of: providing a solar cell substrate; providing an active solder having at least one type of soldering alloy mixed with 6 wt % or less of at least one type of active component and 0.01-2.0 wt % of at least one type of rare earth element (Re); firstly melting the active solder at a temperature lower than 450° C.; then applying the molten active solder on the solar cell substrate (or firstly applying and then melting); and cooling to solidify the active solder, so as to form an electrode pattern.