Corrosion resistance and electrochemical migration behavior of InSnBiAgxZn low-melting-point alloy solders

With the ongoing advancements and innovations of electronic device, the demand for low-melting-point solder is rising, especially for flexible printed electronics. The service environments of electronic device are complex and diverse, which have raised concerns regarding long-term service reliability in solder materials. In this work, a novel type of 30In33Sn25Bi4AgxZn low-melting-point alloy solder was proposed. The effects of Zn content on the corrosion resistance and electrochemical migration (ECM) resistance of the alloy system were investigated through electrochemical test and water drop test (WDT). The passivation film on the surface and the amorphous region of InSnBiAg8Zn alloys effectively inhibits the anodic dissolution of Zn atoms, improves the corrosion resistance of the alloy and delays the occurrence of electrochemical migration failure. The microscopic mechanism of ECM was revealed by conducting in-situ observations of the migration process of the alloy solder and analyzing the composition and morphology of the anode alloy and the migration products.