Effect of Ni addition into the Cu substrate on the interfacial IMC growth during the liquid-state reaction with Sn–58Bi solder

Influences of Ni addition into Cu–xNi alloy on the microstructure evolution and mechanical property of Sn–58Bi/Cu–xNi solder joint

“…Whether for Sn-58Bi/ Cu-1.5Ni system or Sn-58Bi/Cu-5Ni system, only a single (Cu,Ni) 6 Sn 5 was observed at the interface, and there was no Cu 3 Sn phase detected at reflow soldering stage. Similar phenomenon has been reported in the previous study, in which the Cu 3 Sn phase was completely eliminated when 5 or 10 wt% Ni was added to copper substrate regardless of the reaction time [6]. Maeshima et al have explained that the formation of Cu 3 Sn phase was based on the synergistic effect of the diffusion rates between the Cu and Sn atoms, and especially Cu atoms provided by the substrate were the main (2) Cu 6 Sn 5 + 9Cu = 5Cu 3 Sn factor during the liquid-state reaction [37].…”

“…This growth mechanism has been found in some studies, and it could be attributed to the atomic diffusion. It was interesting that at the same reflow soldering stage, the IMC layer became thicker with more Ni addition ranging from 0 to 5 wt%, but significantly decreased in Sn-58Bi/ Cu-10Ni joint system, and the similar result had been found in previous study [6]. Thus, it could be concluded that when 10 wt% Ni was added to the Cu-xNi alloy, the growth rate of the IMC layer would decrease under the influence of the Ni elements.…”

“…Zou et al have explored the influences of small amount of Ag, Al, Sn or Zn addition to Cu substrate on the microstructure evolution of the joint and found that these microelements could not only restrain the interfacial Bi segregation, but also reduce the formation of voids at the interface between the solder and substrate [29]. In our previous study, the Cu-Ni alloying was also found to inhibit the formation of the Cu 3 Sn phase, which could suppress the formations of kirkendall void and Bi segregation in the Sn-58Bi/Cu-xNi joint [6].…”

“…In the past, the tin-lead solder was commonly used due to its good wettability and low melting point [1][2][3][4][5], but due to the consideration of environmental protection, this toxicity solder was forbidden to use by the regulation of hazardous substances (RoHS) and gradually replaced by lead-free solders in modern electronics industries [6][7][8][9][10]. As a kind of conventional lead-free solder, the Sn-58Bi has drawn a great deal of attention in the field of research owing to its excellent properties, such as the relatively low melting point (138 °C), superior creep resistance and high tensile strength [11][12][13][14].…”

Pressure-assisted soldering of copper using porous metal-reinforced Sn58Bi solder

“…At present, Sn-Bi, Sn-Cu, and Sn-Ag-Cu alloys have been used in the packaging industry. Among these alloys, Sn58Bi (SnBi) alloy presents great potentials in low-temperature packaging materials due to its superior solderability, low cost, and melting temperature [6][7][8][9][10][11]. However, the bismuth coarsened during solidification degrades the mechanical property [12][13][14].…”