Abstract
In this study, the interfacial reactions and mechanical properties of solder joints after multiple reflows were observed to evaluate the applicability of the developed materials for high-temperature soldering for automotive electronic components. The microstructural changes and mechanical properties of Sn-Cu solders regarding Al(Si) addition and the number of reflows were investigated to determine their reliability under high heat and strong vibrations. Using differential scanning calorimetry, the melting points were measured to be approximately 227, 230, and 231 °C for the SC07 solder, SC-0.01Al(Si), and SC-0.03Al(Si), respectively. The cross-sectional analysis results showed that the total intermetallic compounds (IMCs) of the SC-0.03Al(Si) solder grew the least after the as-reflow, as well as after 10 reflows. Electron probe microanalysis and transmission electron microscopy revealed that the Al-Cu and Cu-Al-Sn IMCs were present inside the solders, and their amounts increased with increasing Al(Si) content. In addition, the Cu6Sn5 IMCs inside the solder became more finely distributed with increasing Al(Si) content. The Sn-0.5Cu-0.03Al(Si) solder exhibited the highest shear strength at the beginning and after 10 reflows, and ductile fracturing was observed in all three solders. This study will facilitate the future application of lead-free solders, such as an Sn-Cu-Al(Si) solder, in automotive electrical components.
Highlights
The use of Pb-bearing solders has been restricted due to international environmental regulations, such as legislation for end-of-life vehicles (ELVs) and waste electric and electronic equipment (WEEE) [1,2]
This appears to be because were and 7% higher than those blocked of the SC07 solder
The microstructural changes and mechanical properties of SC07, SC0.01Al(Si), and SC-0.03Al(Si) solders were investigated according to the number of reflows
Summary
The use of Pb-bearing solders has been restricted due to international environmental regulations, such as legislation for end-of-life vehicles (ELVs) and waste electric and electronic equipment (WEEE) [1,2]. Such Pb-bearing solders have been replaced by SnAg-Cu solder in electronic products, for which the usage environment is relatively less severe [3]. Sn-Sb solder can be used at high temperatures owing to its relatively high melting point, but its continuous use Materials 2021, 14, 2367 voids and low wettability caused by the oxidation problem [9]. Sn-Sb solder can be used at high temperatures owing to its relatively high melting point, but its continuous use is unpredictable because thethe harmfulness of Sb hashas yetyet to be verified
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