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Solder Joint Analysis of Tin-Lead and Bismuth Based Lead Free PV Ribbons in High Throughput Manufacturing
N.S. Pujari, J. Sundaramurthy, S. Sarkar, E. Poh, C. Bilgrien
Solar Cell, Soldering, Solder Joints
New Materials and Concepts for Photovoltaic Devices
Subtopic: New Materials and Concepts for Cells and Modules
Event: 35th European Photovoltaic Solar Energy Conference and Exhibition
Session: 1CV.4.83
210 - 214
ISBN: 3-936338-50-7
Paper DOI: 10.4229/35thEUPVSEC20182018-1CV.4.83
0,00 EUR
Document(s): paper


PV module manufacturers increasingly require higher throughput production lines with higher degrees of automation and flexibility. Establishing an electrical connection between solar cells in a module not only defines the final shape and output power of the solar panel, depending on the strategy applied it but also strongly impacts yield and throughput of the entire module factory. There are not too many reports on solder joint analysis in high manufacturing scenario. This paper analyses solder joints and factors affecting solder joints in high throughput manufacturing. Paper also report performance of new lead free solder, EcoSolâ„¢ along with standard tin lead ribbon in an automated tabbing machine. We found that under identical conditions, the solder joints in lead and lead free ribbons were comparable and peel strength of >2.5 N/mm on front and back side of the cell obtained. DOE results reveal that the cell metallization play an important role in determining quality of solder joints. Grade A PERC cells yielded higher peel strength compared to p-type c-Si cells due to the smooth surface topology. Similarly, flux having good wetting time performed better. Ribbon alignment was identified as one of the major causes of the weak solder joints. Due to decreased ribbon and bus bar size, this problem might occur frequently. Microscopic investigation yielded, absence of IMC (intermetallic compound) in either of the ribbons due to rapid production speed. Only diffusion of tin into silver matrix was observed. This, however, does not have any effect on peel strength and cohesive failure was evident from fracture surface analysis.