摘要
Low-temperature solders have gained increasing attention in modern electronic packaging for their potential to reduce reflow temperatures and minimize thermal warpage during assembly. This study investigates the interfacial reactions and microstructural evolution of Ag–In intermetallic compounds (IMCs) using a thin-Ag/thick-In dual-layer structure under isothermal reflow at 160 °C, 170 °C, and 190 °C. A distinct AgIn2 IMC layer formed rapidly within 1 min of reflow. After longer reflow, AgIn2 gradually decomposed to Ag9In4 at 170 °C and 190 °C, while the microstructure remained stable without phase transformation at 160 °C. At higher temperatures, the Ag under-bump metallization (UBM) was rapidly consumed, leading to pronounced spalling of AgIn2 IMCs at the interface. These results reveal the highly reactive nature of the Ag/In couple and elucidate its phase transformation behavior under liquid-assisted conditions. The demonstrated low-temperature reflow capability of the Ag–In system offers promising potential for reducing process temperature, warpage, and energy consumption in advanced packaging, thereby supporting key Sustainable Development Goals (SDGs) and broader sustainability initiatives.
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•Ag–In structure was performed to investigate interfacial reaction during reflow.•The growth IMCs were identified as AgIn2 phase before 8 min reaction.•AgIn2 transformed to Ag9In4 after 10 min at 170 °C and 190 °C.•Rapid Ag UBM consumption was observed at 170 °C and 190 °C.