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66 SMT007 MAGAZINE I JULY 2022 in both damp heat and thermal cycling tests. ese results demonstrate that OM550 HRL1 paste is resistant to oxidation and is resistant to changing weathering conditions. ese results further confirm that the standard tin-lead and lead-free low-temperature-alloy paste can be used for interconnecting IBC cells. e paste can withstand the expansion and compression forces produced during thermal cycling. Conclusion We report low temperature lead-free solder paste for interconnecting IBC cells. We found an acceptable wettability and printability of this paste. e paste shows excellent stability, longer stencil life, and consistent transfer effi- ciency. A seven-zone reflow oven was used for the study to analyze and evaluate solder paste performance. OM-550 paste with 190°C to 210°C peak temperature slow ramp profile and conveyor speed (28 inches/minute) yields reli- able bond strength. Solder joints were strong with peel strength more than 2 N/mm and voiding less than 10%, indicating bonds have better contacts and complete wetting has hap- pened. Paste could be fast reflowed and lami- nated with EVA. e modules assembled using this paste pass thermal cycling and damp heat reliability testing according to IEC 61215. Based on these results we conclude that the solder paste can be used to make IBC cell interconnection and other advanced inter- connection assemblies. SMT007 References 1. "Back-contact solar cells: a review," by E. Van Kerschaver, G. Beau- carne, Prog Photovolt Res Appl. 2006; 14(2):107-123. 2. "Three-dimensional multi-ribbon interconnec- tion for back-contact solar cells," by R. Van Dyck, T. Borgers, J. Govaerts, J. Poortmans, and A.W. Van Vuure, Prog Photovolt Res Appl, 29(5), pp.507-515. 3. "Lead-free low temperature solder pastes for shingling interconnection," by N.S. Pujari, Krithika PM, P. Vishwanath, S. Sarkar, and C. Bilgrien, 37th European Photovoltaic Solar Energy Conference and Exhibition, Lisbon, Portu- gal, 2020, pp. 29-32. 4. "Stencil printing of solder paste for fine-pitch surface mount assembly," by J.R. Morris, and T. Wojcik, IEEE Transactions on components, hybrids, and manufacturing technology, 1991, 14(3), pp.560- 566. Narahari Pujari is senior global technology manager, PV and applied materials, at MacDermid Alpha Electronics Solutions. Krithika PM is a research scientist at MacDermid Alpha Electronics Solutions. Figure 12: Electroluminescence analysis for ECA and OM-550, up to 2,000 hours of damp heat studies.