What are the specifications of photovoltaic module solder

Photovoltaic module solder typically consists of tin-lead (Sn-Pb) or tin-silver-lead (Sn-Ag-Pb) alloys, designed for high thermal reliability and electrical conductivity in PV ribbon joints.Common Solder Alloys

1. 60Sn40Pb (SP): A traditional tin-lead solder widely used in PV ribbon joints, offering good wetting and electrical conductivity.
2. 62Sn2Ag36Pb (SAP): A tin-silver-lead solder that improves thermal fatigue resistance and mechanical strength due to the addition of silver, which enhances the microstructure stability under thermal cycling .

Thermal and Mechanical Properties

• Melting Temperature: Typically around 183–190°C for 60Sn40Pb and slightly higher for 62Sn2Ag36Pb due to silver content.
• Thermal Shock Resistance: PV module solder must withstand repeated temperature cycles, commonly tested between −40°C to +105°C, simulating environmental conditions .
• Mechanical Reliability: Solder joints must maintain adhesion to metal fingers and PV cells, resisting cracks and delamination that can lead to hotspots or power loss .

PV Module Solder Joint Design

• Ribbon Size: Standard PV ribbons are approximately 0.25 mm thick and 1.5 mm wide.
• Soldering Process: Ribboned cells are soldered at around 350°C, followed by lamination under vacuum and heat curing to ensure strong electrical and mechanical connections .
• Quality Control: Non-invasive methods like eddy current testing and electroluminescence imaging are used to detect cold solder joints, cracks, or conductivity degradation .

Performance Considerations

• Environmental Durability: Solder must resist thermal cycling, humidity, and UV exposure over the module's lifetime.
• Electrical Conductivity: High conductivity is essential to minimize resistive losses in the PV module.
• Degradation Monitoring: Broken metal fingers and solder microstructure changes are analyzed to predict module longevity and efficiency loss . In summary, PV module solder specifications focus on alloy composition, thermal and mechanical reliability, and long-term electrical performance, with 60Sn40Pb and 62Sn2Ag36Pb being the most common alloys used in crystalline silicon PV modules .