Removal of Oxide Film and Wetting Behavior of Sn9Zn–xSiC Composite Solder on 6061 Aluminum Alloy with Activated Organic Water-Soluble Flux

The effect of Sn9Zn–xSiC composite solder on the wetting and soldering behavior of 6061 aluminum alloys is investigated using a kind of new water-soluble organic flux through optical and electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The oxide film of 6061 aluminum alloys during the soldering process is composed of three-layer structure of different components, which are followed MgAl 2 O 4 , Al 2 O 3 and Al from the outside to the inside. The flux removes the oxide film by the dissolution reaction. A solid solution layer can be developed by undergoing displacement reaction with the Al-rich phase. With the increasement of SiC micron particle content, the spreading area of the composite solders increases firstly and then decreases. When the weight percentage of SiC micro-particles in the composite solder was 0.75%, the spreading area reached the maximum value, which increased by 38.9% compared with Sn9Zn–0.25SiC composite solder. Graphic Abstract