Study On Microalloying Of Sn0.3Ag0.7Cu Series Solder Alloy And Its Preparation Technology Of Micro Powder

Surface mount technology(SMT)is a comprehensive engineering science and technology in the electronic assembly field.All of the electronic hardware assembly take the SMT as the core technology in the world.The SMT process has higher requirements on the performnce of welding materials.The research on green lead-free materials,improving the reliability of solder joints and reducing the cost of materials is still in progress.In this paper,the effect of rare earth Ce on the microstructure,physical properties and reliability of solder joints of low Ag content Sn0.3Ag0.7Cu alloy is studied.It is hoped that the alloy with the best performance is obtained.The effect of atomization pressure on the properties of Sn0.3Ag0.7Cu0.05Ce powder and the effect of rare earth Ce on the properties of Sn0.3Ag0.7Cu series alloy powder were studied by means of supersonic gas atomization.The optimum process and the addition amount of rare earth Ce were obtained.And we obtained the best process conditions and the best Ce addition amount.We had achieved the following findings:(1)The microstructure of Sn0.3Ag0.7Cu series alloy was refined.The growth of solder/Cu interface IMC was suppressed effectively,the solder spreading rate,hardness,shear strength of alloy are increased with the addition of rare earth Ce.The optimum addition amount of rare earth Ce was in the range of 0.05 to 0.07wt.%(2)The solder/Cu interface IMC thickness increasing gradually,the morphology of IMC changing from hackly facture to wavy and lamellar,the shear strength decreasing gradually when the aging time increased at 150 ? isothermal aging.And the fracture form of the solder joint changed from ductile fracture of the microporous polymerization to the cleavage fracture.The addition of rare earth Ce could effectively inhibit the growth of IMC layer during the aging process.(3)In the atomization pressure range of 0.4-0.7MPa,Sn0.3Ag0.7Cu0.05Ce powder was prepared.When increased the atomization pressure,the effective atomization rate increasing,the median diameter of the powder decreasing,the particle size distribution range becoming narrow,and its sphericity improving.When the atomization pressure reached to 0.8MPa,the effective atomization rate decreasing,and the powder performance deteriorating.The optimum atomization pressure was 0.7 MPa in this experiment.(4)The addition of rare earth Ce effect on the performance of atomized Sn0.3Ag0.7CuxCe(x=0,0.05,0.10,0.15)solder powder.With the addition amount of the rare earth Ce increasing,the effective atomization rate of the powder was improved,the median diameter of the powder was reduced,the particle size distribution was narrowed,and the sphericity was improved.The best addition amount of rare earth Ce was 0.10wt.%.