Creep properties of Sn–Sb based lead-free solder alloys

Thermal and mechanical properties of Sn–Zn–Bi lead-free solder alloys

“…and Sn-9Zn-4Bi alloys, respectively. These activation energies are relatively close to that for the pipe-diffusion-controlled creep of tin (35-62 kJ/mol) [27]. Therefore, it can be concluded that this mechanism dominates in the three lead-free solders in the stress and strain rate range investigated.…”

“…However, the addition of small amount of Bi expands slightly the temperature interval of the pasty range (T end − T onset ), which is the difference between the liquidus (T end ) and solidus (T onset ) temperature. 1% Bi addition causes the measured pasty range of Sn-9% Zn to change from 5.3 to 7.2 • C; whereas, the addition of an amount of 4% Bi increases the pasty range to 8.1 • C, which is lower than 11.5 • C for Sn-Pb eutectic [21]. Moon et al [22] have reported that a large pasty range increases the tendency towards porosity and hot tearing due to the effect of alloy shrinkage and differential thermal contraction during solidification.…”

“…where k is a constant with the value of 2.64 for pure tin [21], which is defined as a calibration coefficient that depends on crucible shape, m is the mass of the sample, and A is the area under the endothermic peak. From Table 2, A/m is determined as 72.7, 69.6, and 61.9 J/g for Sn-9Zn, Sn-9Zn-1Bi and Sn-9Zn-4Bi alloys, respectively.…”

“…On the other hand, the elongation of Sn-9Zn-1Bi is higher than that for the other two alloys at high temperature range, but the binary Sn-9Zn solder exhibits much higher elongation than the ternary Sn-Zn-Bi solders at low temperatures. In view of the fact that Sn and Zn have different lattice structures, the nature of interface must be either incoherent or semi-coherent, and there is a good possibility that the interface is a high diffusivity path for Zn or O along the Sn grain boundaries to dominate the oxidation process [27]. Also, the change from SnBi to Bi, which however, reducing the solder joint's ductility, inducing brittle fracture, influencing crack initiation and accelerating the fatigue crack growth kinetics due to de-cohesion of large Bi particles that deteriorates the homogeneity of the mechanical properties.…”

Ternary intermetallic compounds in Au–Sn soldering systems—structure and properties

“…It has been described in the NiAs structure type with lattice parameters of a & 4.32 Å and c & 5.52 Å [13,14]. Moreover, AuSn or its pseudo-binary compounds can be generated if eutectic InSn or SnSb solders are used with an Au coating or an Aucontaining substrate [15][16][17][18]. In addition to the reactions in Au-Sn solder joints, AuSn or its pseudo-binary compounds can be generated if eutectic In-Sn or Sn-Sb solders are used with an Au coating or an Au-containing substrate [15][16][17][18].…”