| One of the valid methods to improve the microstructure and mechanical properties is incorporating foreign reinforcements into the solder matrices to prepare SAC composite solders. Thus, in this paper, SiC whiskers(SiCw) as the reinforcements with different weight fractions(0, 0.01, 0.05 and 0.1 wt.%) were successfully incorporated into Sn-3.0Ag-0.5Cu(SAC305) lead-free solder paste through mechanical mixing method. After that, the prepared SAC-xSiCw composite solders were studied concerning their melting temperature, wettability, microstructures, mechanical properties as well as the growth of interfacial intermetallic compounds(IMCs).After the SiCw addition, the refined eutectic phases and decreased average spacing between IMCs were observed in the solder matrices. With the adding amount of SiCw increasing, the composite solders showed a corresponding improvement in their wettability while an ignorable change was found in melting temperature. Compared with the plain SAC solder, when 0.1 wt.% of SiCw was added, contact angle of the composite solders between Cu substrate was decreased by 11.5% and the microhardness and shear strength could be increased by 30.3% and 11.2%, respectively. Moreover, the fracture morphology of SiCw reinforced composite solders joints exhibited a typical ductile fracture mode while the unreinforced SAC solder showed a relatively brittile fracture morphology. In addition, the SAC composite solder with 0.1 wt.% addition of SiCw was found to have thinner interfacial IMCs than SAC solder during the multi-metling process and isothermal aging process. Meanwhile, the polarity effect in electromigration process was investigated as well with 6 A current and 1.05 × 104 A/cm2 current density, the results shown that the polarity effect of the interface of composite solder joints was improved. |
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