Ultrasonic-assisted soldering of aluminium and copper with Sn–Zn–Bi–Ag solder

Abstract

The effects of ultrasonic-assisted soldering parameters on the interfacial microstructural evolution and shear strength of designed Al/Sn–9.77Zn–11.36Bi–1.46Ag/Cu solder joints were investigated. The ultrasonic-assisted soldering process promoted the dissolution of Al substrate and roughed Al/solder interface, which improved the pinning effect of Sn–9.77Zn–11.36Bi–1.46Ag on Al substrate. With an increasing ultrasonic soldering temperature, time and power, more Al atoms dissolved from Al substrate and migrated across solder to the opposite Cu substrate to form Al-rich (Zn) solid solutions. Consequently, Al_4.2Cu_3.2Zn_0.7 formed between ϵ-AgZn₃ and Cu₅Zn₈ layers at Cu substrate, resulting in thinner Cu₅Zn₈ and higher shear strength of solder joints. The highest shear strength of solder joints (38.6 MPa) was achieved after ultrasonic-assisted soldering at 300°C for 10 s under 9 W.

KEYWORDS:

• Dissimilar metal joining
• ultrasonic-assisted soldering
• aluminium and copper
• interfacial intermetallic compound
• Sn–Zn–Bi–Ag solder

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is supported by the National Natural Science Foundation of China under [Grant numbers U1837208 and 51671046], and the Fundamental Research Funds for the Central Universities under [Grant number DUT20LAB122].