Synergetic role of Ni and GOns to improve the microstructure and mechanical creep rate of Sn-5.0Sb-0.7Cu solder alloy

Abstract

The role of minor additions of Ni and GOns to Sn- 5 wt.% Sb- 0.7 wt.% Cu (SSC-507) has been explored. Findings of scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffractometry (XRD) display the new phases like (Cu,Ni)6Sn5 and the size decrement of β-Sn grains. A slight increase in the melting temperature was observed using differential scanning calorimetry (DSC) analysis due to adding Ni (ΔTm =1.02 oC) and GOns (ΔTm =0.75 oC). Interestingly, 0.1 wt% Ni addition reduced the under-cooling by ~28 %, whenever adding of 0.1 wt% GOns enhanced the under-cooling by ~115 %. The average size of β-Sn grains of SSC-507 plain solder was decreased from ~150 to ~ 70 μm due to adding of Ni and then GOns. The enhanced creep resistance of SSC-Ni-GOns alloy motivated the values of creep fracture and enhanced the stress exponent parameters (n) by ~ 27%. The outcomes of tensile creep examination demonstrate that increasing levels of stress and testing temperatures raise the steady-state creep rates for all tested alloys. The average activation energy (E) for the three solders ranged from ~ 46.5 kJ/mol to ~ 54.3 kJ/mol which close to that of pipe-diffusion mechanism in Sn based solder alloy.

Correlation of microstructure with thermal and tensile creep properties of novel Sn-5Sb-0.5Cu alloy reinforced with Co particles for soldering applications

“…Consequently, the improvement in creep resistance was mostly due to the finer grain size of the β-Sn grains and the more uniform dispersion of the IMC particles. The same dependency was obtained by Mousa et al [33].…”

“…The thermal profiles obtained during heating lead-free SSC solder specimens doped with 2. These values are largish than that for SSC507 solder (7.1 °C) [33], Sn-0.7Cu-0.5Co solder (6.6 °C) [43], and close to 11.5 °C for Sn-Pb eutectic [44]. The observed reduction in the pasty range for 0.25, 0.75, and 1 wt% of Co additions has significant effects on both the performance and reliability of SSC-xCo solders in electronic service as they facilitate rapid soldering, decreased porosity, and the possibility of fillet lifting.…”

“…So, the very small grain size and the more uniform β-Sn phase and newly dispersed IMC particles will be the main reason for creep resistance enhancement when SSC is doped with x wt.% Co. The newly generated phase (Cu,Co) 6 Sn 5 of small quantity (on the expense of Cu 6 Sn 5 phase) accompanied with a slight dimension in the average β-Sn rich phase grain size in SSC-0.25Co alloy (see figures 3(b) and 4(b)) results in little raise in the creep resistance due to the reduction in the surface energy by arranging the orientation relationship between the matrix and precipitates, a matter that provides largish barriers for dislocation motion [33]. The subsequent decrease in creep strains and creep rates with 0.5Co addition indicates that creep resistance of SSC-0.5Co alloy is mainly affected by; the formation of new CoSn 3 phase of small numbers and sizes, the large amount of (Cu,Co) 6 Sn 5 IMC, the formation of nearly uniform & small-sized equiaxed β-phase, and the considerable decreasing of the eutectic structure (see figures 3(b), (c) and 4(b), (c)).…”

“…Additionally, they found that the average activation energies (Q) for the plain and composite solders were 57 and 59 kJ mol −1 , respectively, which are comparable to the pipe-diffusion mechanism in the Sn-based solder matrix. Mousa et al [33] reported that minor additions of Ni into Sn-5 wt%Sb-0.7 wt%Cu (SSC-507) slightly increased melting temperature, reduced the under-cooling by ∼28%, refined the size of β-Sn grains and displayed new phases like (Cu,Ni) 6 Sn 5 . Cobalt element (Co) belongs to the most desirable alloying materials because it improves the mechanical properties of solder and reduces undercooling [34][35][36][37].…”

Evaluation of the microstructure, thermal, and mechanical characteristics of Sn-9Zn reinforced with Ni and ZrO2 nanoparticles via vacuum melting process

“…Nickel's overall importance in soldering is growing, where Ni is utilized as a barrier to diffusion within Cu and Sn in order to avoid and slow the production of Cu 3 Sn and Cu 6 Sn 5 intermetallic phases during soldering or to extend the shelf life of printed circuit boards (PCBs) with solderable tin plated surface finishes [23][24][25]. Interfacial reactions between Sn-Zn solder and Ni were studied by Wang et al [26] They found that the Sn-9wt% Zn/Ni interfacial reactions are controlled by diffusion processes and that Ni 5 Zn 21 is the predominant produced phase for solid-state ageing between 150 °C and 170 °C and liquid-state ageing between 230 °C and 270 °C.…”