Ultrasonic-assisted soldering of SiC ceramic and aluminum alloy with a commercial inactive Sn3.0Ag0.5Cu solder

Abstract

Achieving the joining of SiC ceramic and Al alloy will be potential for the broad application of high-power IGBT packages. This work proposes a novel strategy of using the commercial Sn3.0Ag0.5Cu inactive solder to achieve an active bonding between SiC ceramics and 6063Al alloy. The ultrasound promotes the intensive dissolution of Al into the solder, resulting in the solder being activated and the interfacial reaction between the SiC ceramic and solder triggered by the acoustic cavitation effect. At a shorter ultrasonic action, The dissolution of Al-based metal by the Sn3.0Ag0.5Cu solder was low, and the Al/solder interface became uneven and precipitated fine Ag3Al2 and Al2Cu compounds in the solder. While the amount of Al dissolved by the Sn3.0Ag0.5Cu solder increased sharply, obvious notches were found at the Al/solder interface, and a large amount of α-Al precipitates in the solder under a longer ultrasonic duration (>10 s). The SiC/solder interface evolved from partial bonding to full metallurgical bonding with the prolongation of ultrasonic actions. The shear strength of the obtained SiC and 6063Al joints reached 35 MPa at the ultrasonic time of 40 s. The amorphous Al2O3 mixed with γ-Al2O3 grains was formed in the SiC/solder interface and 6063Al/solder interface. Based on the effect of acoustics cavitation and thermodynamics, the formation mechanism of the interfacial reaction layer was discussed in detail.