Analysis of peel and shear forces after temperature cycle tests for electrical conductive adhesives
Soldering of copper ribbons on busbars is the standard process for the series interconnection of solar cells in industrial PV modules. As an alternative interconnection approach electrical conductive adhesives (ECAs) can be used for cell interconnection. ECAs are lead free and can be processed at temperatures below 200°C. However, the higher costs and the lower adhesive forces between interconnector and solar cell compared to established solder-based interconnection prevented a larger market share until now. We present results of 90° peeltests according to DIN EN 61189-2:2006 and shear tests according to DIN EN 1465 for seven commercially available ECAs and a comparison to the electrical performance of corresponding 3-cell modules in the temperature cycle test according to IEC 61215. The results show that all samples pass the temperature cycle test with a loss of power below 5%. The measured peel forces decrease after TC600 whereas the shear forces remain at their initial level.