Under CopyrightGüldali, DeryaDeryaGüldaliDe Rose, AngelaAngelaDe RoseOeser, SabineSabineOeserKraft, AchimAchimKraftTetzlaff, UlrichUlrichTetzlaff2024-11-142024-11-142023Note-ID: 00008B7Ehttps://publica.fraunhofer.de/handle/publica/478916https://doi.org/10.24406/h-47891610.4229/EUPVSEC2023/3AV.1.410.24406/h-478916The temperature sensitivity of new solar cell technologies forces to use solder alloys with lower melting temperatures for interconnection [1].Our study explores the dynamics of intermetallic phase growth and microhardness in Sn42Bi58 solder joints applied to low-temperature silver metallization on silicon heterojunction (SHJ) solar cells. Through rigorous experimentation and analysis, a comprehension of the influence of these factors on the mechanical and material properties of the solder joint is achieved. Microstructural changes in Sn42Bi58 solder compared to conventional tin-lead solder are investigated through microscopy of cross sections, revealing enlarged intermetallic particles and phase boundary growth. These changes, attributed to lower homologous temperature of the low-melting solder, are expected to negatively impact the mechanical strength of the solder joint. For the intermetallic phase Ag3Sn simulations predict a potential layer thickness of 20 µm after 25 years SHJ module operation. Our results show that the Ag3Sn phase has a significant impact to the microhardness. Following the aging process, the nano hardness of the low temperature Ag metallization experiences a twofold increase, shifting from 660 ± 53 N/mm² to 1367 ± 411 N/mm². This strengthening is primarily attributed to the prevailing influence of the Ag3Sn intermetallic phase.eninterconnectionintermetallic compoundsLead-free solderinglong-term stabilitymicrohardnessconference paper