Investigation of the Sn-0.7 wt.% Cu Solder Reacting with C194, Alloy 25, and C1990 HP Substrates

Abstract

Cu-based alloys are one of the most promising substrates to enhance the performance of lead-frame materials. In the present study, the interfacial reactions in the Sn-0.7 wt.% Cu (SC) lead-free solder reacting with Cu-3.3 wt.% Fe (C194), Cu-2.0 wt.% Be (Alloy 25), and Cu-3.3 wt.% Ti (C1990 HP) were investigated. The material underwent a liquid–solid interface reaction, and the reaction time was 0.5 to a few hours at the reaction temperatures of 240 °C, 255 °C, and 270 °C. The morphology, composition, growth rate, and growth mechanism of the intermetallic compounds (IMCs) formed at the interface were investigated in this study. The results showed that the reaction couples of SC/C194, SC/Alloy 25, and SC/C1990 HP formed IMCs, which were the [(Cu, Fe)6Sn5 and (Cu, Fe)3Sn], [(Cu, Be)3Sn and (Cu, Be)6Sn5], and [Cu6Sn5] phases, respectively. Finally, the IMC growth mechanism for the SC/C194, SC/Alloy 25, and SC/C1990 HP couples displayed reaction control, grain boundary diffusion control, and diffusion control, respectively.

Interfacial reactions in the Sn-9.0 wt.% Zn/Cu-Ti alloy (C1990 HP) couple

“…However, the limited quantity of Ti present in C1990 HP did not induce any alteration in the phase. Additional discoveries indicate that the introduction of a small amount of Ti into Cu to create C1990 HP results in an amplified growth of the IMC and extensive spalling of the Cu 6 Sn 5 phase in the reaction couples of Sn/C1990 HP (Laksono et al , 2019, 2022a, 2022b), Sn-0.7 wt.% Cu/C1990 HP (Laksono et al , 2023) and Sn-3.0 wt.% Ag-0.5 wt.% Cu/C1990 HP (Yen et al , 2019a) during the liquid/solid reaction. The spalling phenomenon was observed to vary with changes in reaction time and temperature.…”

“…Copper (Cu) is commonly used as a metallic coating material in printed circuit boards and is ideal for solder joint bonding due to its superior solderability (Yen et al, 2008;Laurila et al, 2005). To improve the reliability of a solder joint, various alloying elements are added to Cubased substrates to allow interfacial reactions to occur, as seen in our previous studies, such as Cu-Be (Yin et al, 2020b(Yin et al, , 2020cLi et al, 2021), Cu-Fe (Yin et al, 2020a) and Cu-Ti (Laksono et al, 2019;Wang et al, 2021;Laksono et al, 2022aLaksono et al, , 2022b. The addition of Ti to Cu reportedly confers conductive properties and good reliability (Soffa and Laughlin, 2004).…”