Effects Of Ag₃Sn Nanoparticles And Sb Element On The Properties Of Sn-3.0Ag-0.5Cu Solder Allo

Electronic packaging technology is widely used in the production and manufacturing of electronic products.As a connecting material,welding materials are used to achieve the assembly of electronic components and printed circuit boards through soldering.As the electronic industry begins to pursue green manufacturing,the requirements for solder have also increased,and the use of Sn-Pb solder has been prohibited.With the enhancement of environmental awareness,Sn-Pb solder is no longer suitable for the electronic industry.However,due to the special composition of Sn-Ag-Cu based lead-free solder,it can form intermetallic compounds such as Ag₃Sn and Cu₆Sn₅,resulting in an increase in the thickness of the IMC layer and a reduction in welding quality.Therefore,in this paper,Sn-3.0Ag-0.5Cu（SAC305）lead-free solder was selected as the substrate,and different amounts of Ag₃Sn nanoparticles were added to it.On this basis,Sb element was added.The effects of Ag₃Sn nanoparticles and Sb element on the microstructure,melting performance,wettability,IMC growth,shear strength,and IMC growth and shear strength of SAC305 solder after aging at 150℃for different times were studied.The research shows that when an appropriate amount of Ag₃Sn nanoparticles is added to SAC305 solder,the effect of grain refinement is achieved because Ag₃Sn nanoparticles provide a new nucleation point for the molten alloy,and the effect of grain refinement is most obvious when the addition amount reaches 0.5 wt.%.With the addition of Ag₃Sn nanoparticles,the melting properties of composite solder alloys have little change,so the relevant processes and equipment for lead-free solder can continue to be used.In terms of wettability testing,with the addition of Ag₃Sn nanoparticles,the wetting time of the composite solder alloy decreases,the wetting force increases,and the wettability increases.This is due to the high surface energy of Ag₃Sn nanoparticles,which reduces the surface energy of the molten solder,improves the fluidity of the molten solder,and thus improves the wettability.In terms of the growth of interfacial IMC,it was found that the addition of Ag₃Sn nanoparticles improved the morphology of the IMC layer,reduced the thickness of the IMC layer,inhibited the excessive growth of the IMC layer,and improved the shear strength.After aging at 150℃,it was found that the addition of Ag₃Sn nanoparticles can effectively inhibit the growth of IMC layers,and after thermal aging,composite solder joints still have high shear strength.Based on various performance tests,it is concluded that the composite solder has the best comprehensive performance when the addition amount of Ag₃Sn nanoparticles is 0.5wt.%.Different amounts of Sb element were added to the Sn-3.0Ag-0.5Cu-0.5Ag₃Sn nanoparticle composite solder.It was found that part of Sb would be solidly dissolved in Sn,and the other part would form Sn Sb intermetallic compounds.In the matrix structure of the composite solder,it was found that due to the increase in heterogeneous nucleation points,the nucleation process of the grains was accelerated,resulting in an increase in the number of small grains,thereby inhibiting the growth of the grains and achieving the effect of refining the grains.Due to the high melting point of the added Sb,the solid solution of Sb in Sn leads to an increase in the melting point of the composite solder,an increase in the melting range,and a decrease in the melting performance.Moreover,the wetting performance will also decrease with the increase in the Sb content,but the overall impact is not significant,and the existing processes and equipment can still be used.Due to the solid solution strengthening of Sb,after reflow soldering,the scallop like IMC layer of the composite solder becomes more dense,making the solder joint more reliable.Moreover,after aging at 150℃,the IMC growth rate is only 3.6985×10^-7μm²/s。Based on the addition of Ag₃Sn nanoparticles,further reduction is achieved.Due to the close relationship between the IMC layer thickness and solder joint reliability,the composite solder achieves higher solder joints.Adding an appropriate amount of Sb element can improve the shear strength of solder joints.When the addition amount reaches 3.0 wt.%,the shear strength reaches the maximum,reaching 41.35 MPa.After aging at 150℃,the strength of each composite solder joint decreases,but the shear strength is better than when Sb element is not added.