Study On Fabrication Process And Properties Of Sn-Sb Based Composite High Temperature Solder

Third-generation semiconductor material service conditions more severe,interconnect materials in the device also made higher requirements.In order to meet the high-temperature performance of high-performance stability,the inevitable need to use high temperature solder.The crystal structure,lattice constant,thermal expansion coefficient and high temperature stability of interconnect materials and chips seriously affect the reliability of the device.For the third generation semiconductor substrate materials,the commonly used high thermal conductivity ceramic materials are selected,and the ceramic is the highest hardness with the highest hardness in the project of the material,in order to solder the substrate material with high matching,good bonding strength,inevitably need to improve the mechanical properties of solder.Nanomaterials have been applied in all walks of life for their superior physical properties.In order to improve the comprehensive properties of brazing alloys,two kinds of manufacturing processes were used to prepare Sn-5Sb-nano Cu composite solder.One is to prepare Sn-5Sb-nano Cu composite solder paste by mechanical agitation,the other is to prepare Sn-5Sb-nano Cu composite solder sheet by hot pressing sintering process.The microstructure of composite solder under two kinds of technological conditions is analyzed,and its wetting property,shearing property and microhardness are tested and analyzed.The influence of nano Cu particles on their properties is explored.The results show that the Cu6Sn5 compound is formed when the composite solder reaches the Cu-Sn binary alloy eutectic point at the heating temperature of Sn-Cu binary alloy under the solder paste fabrication process.The nucleation sites as a particle were dispersed in the matrix solder,which refined the microstructure of solder joints body solder,and the effect was more pronounced with the addition of nanoparticles.Adding nano-Cu particles makes the wettability of the composite solder decreased,when the amount of 1.0 wt%,the wettability decreased by 13.4%,to a minimum.In the solder paste production process,adding nano-Cu particles can inhibit the growth of the IMC interface,with the increase in the amount of addition,the more significant inhibition,but its morphology basically no effect.This is because the nano-Cu particles have a high surface energy.According to the adsorption theory,the nano-particles are easily adsorbed on the upper surface of the IMC layer,resulting in a decrease in the surface energy of the IMC layer and an increase in the stability of the crystal plane,thus decreasing the IMC growth rate at the interface.The mechanical properties of Sn-5Sb-nano Cu composite solder paste found that the microhardness of solder brazing filler metal first increased and then decreased with the increase of nano-Cu particle content,and the hardness was the highest when the additive amount was 0.1 wt% of 207.3 MPa,while the Sn-5Sb / Cu solder brazing filler metal microhardness of 162.7 Mpa,an increase of 27.4%.When the added amount of 1.0 wt%,only 183.9 Mpa.The shear strength of the solder joint test shows that the shear strength also increases first and then decreases.When the nano Cu content is 0.3 wt%,the shear strength increases by 13.8%.The addition amount of 1.0 wt%,the shear strength decreased significantly,down 5.1%.The analysis shows that the mechanical properties of the solder joints are improved to a certain extent by the addition of nano-particles due to the combination of fine-grain strengthening and dispersion strengthening.Meanwhile,the number of pores in the solder joint increases due to the addition of nano-particles,and the pores develop as stress concentration points and crack growth potential areas,a serious impact on the mechanical properties of solder joints,resulting in a sharp decline in mechanical properties of solder joints.In the sintering process,Sn-5Sb-nano Cu sintering process parameters identified as sintering pressure 20 Mpa,sintering temperature 180 ?,holding time 60 min.After sintering the composite solder sheet microstructure observation,can be observed after sintering still existing inevitable microcracks.In the microstructure of the dispersed compounds,the analysis of the nanoparticles added after sintering complete reaction of Cu-Sn compounds,not in the form of pure metals.The effect of nano-Cu particles on the wettability of Sn-5Sb solder was analyzed under the sintering process.As a result,the wetting angle increased greatly,that is,the solder wettability decreased obviously.The thickness of the IMC at the solder joint interface after welding was measured.It is found that adding the nano-particles has no effect on the IMC thickness at the solder joint interface.The analysis shows that the nano-particles have completely reacted to form Cu-Sn compound after sintering,so that it is difficult to exert the excellent performance of the nano-particles in the welding process.