To suppress thermal deformation of the organic circuit boards during the reflow soldering,a mechanical mixing method was applied to prepare SnBi-SAC/ENIG hybrid solder joints.The effect of soldering temperature on the microstructure and mechanical properties of the solder joints was studied.The results show that the shear strength of the hybrid solder joint at 180 ℃ is about 25 MPa,which can meet the pre-connection strength requirements for the bonding between chip and the substrate.As the soldering temperature increases,the interfacial microstructure of the composite solder joint becomes refined,and there are some small Bi-rich and Ag3 Sn phases dispersing near the interface.When the soldering temperature reaches 250 ℃,the shear strength of the solder joint increases to approximately 55 MPa.This material is suitable for the low-temperature pre-connection,structural reinforcement,and high-temperature reflow process.It has a significant effect on the thermal deformation suppression of the packaging structures.
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