Design And Property Study On A Sn-Ag-Cu Lead-free Solder Reinforced With Ag-Graphene

Nowadays,with the rapid development of electronic products,the ever-rising demand for miniature,light weight solder joints in electronic packaging has prompted the superfine solder joint has better thermal,mechanical and electrical properties.However,the traditional lead-free solder alloys have been reported to have several drawbacks.Hence,it is imperative to investigate and synthesize the nanocomposite solders.In the present study,the addition of reinforcements into the matrix to improve the performance of the traditional lead-free solder has already become a common method used in this field.Hence,a new-type reinforcement graphene nanosheets(GNSs)decorated by nano-Ag particles(Ag-GNSs)was incorporated into 96.5Sn-3.5Ag-0.5Cu to synthesize composites solders in the study.There are two parts as following:Varying contents of Ag-GNSs and GNSs were resoundingly incorporated into SAC solder using the powder metallurgy route and the performance of the nanocomposite solder was investigated.As the addition of Ag-GNSs increased,the nanocomposite solders prepared by ball milling methods showed the finer intermetallic compounds on the solder matrix and the significant decline of its wetting angles but an unconspicuous change in its melting points.The tensile test results indicated that the UTS of composites were improved but its ductility were decreased.The formation and growth kinetics of the intermetallic compounds(IMC)after soldering and isothermal aging process between composite solder and the substrates were investigated.The results showed that the composite solders reinforced by Ag-GNSs have thinner IMC layer and lower growth rate constant no matter during the soldering or isothermal aging process,which indicated that the addition of Ag-GNSs can efficiently retard the growth of IMC and enhance solder joint’s reliability.Moreover,the QSAC/ 0.05Ag-GNSs has smaller diffusion coefficient 1.59×10-12m2/s as compared to the 1.75×10-12m2/s in the QSAC/0.05 GNSs or 1.82×10-12m2/s in the HSAC/0.05Ag-GNSs,which presented the better reinforcement effect of Ag-GNSs.Besides,the ball milling process can provide more dependable nanocomposite solders.