Investigation On Sn-based Solder Alloys For Soldering 1060 Aluminum

Using aluminum instead of copper in manufacturing productions has better economic benefits.However,as soldering aluminium with solder alloys,there are some common problems such as the dissolution of aluminium substrate,poor wettabilities and poor corrosion resistance of the soldering joints and so on.The Sn-Ag and Sn-Ag-Cu system solder alloys are generally used in soldering aluminium,but the prices are high due to the high content of Ag.The Sn-Cu system solder alloys are also applied in soldering aluminium,but no intermetallic compound is formed near the soldering interface,resulting in the poor corrosion resistance of the soldering joints.As for Sn-Zn solder alloys which have been studied in soldering aluminium,the solder alloys have poor oxidation resistance,poor corrosion resistance and the dissolution of aluminium substrate during soldering.1060 aluminium is used as substrate in the tests.The effects of adding Al,Zn and Cu alloying elements to the Sn solder alloys on the dissolution of aluminium substrate,the wettablities,interfacial reaction behavior and the corrosion resistance of soldering joints are mainly studied in this paper.The test results are as follows:Firstly,adding Al alloying element?0.1¹.5wt.%?to Sn solder can reduce the dissolution of aluminium substrate during soldering.With the Al content increasing,the amount of dissolution of aluminium substrate becomes smaller,the corrosion resistance of soldering joints increases in NaCl solution.However,with the Al content increasing in the solder alloys,the melting range increases,the wettabilities decreases,the?-Al phase becomes more and coarsening.Secondly,adding Zn alloying element?1⁴wt.%?to Sn-1.0Al solder alloy can greatly reduce the start melting point temperature and improve the wettabilities on the aluminium substrate.From the microstrure observation,with the Zn content increasing,the Sn-Zn eutectic structure becomes more,the thickness of solid solution layer?Al-Zn-Sn?increases at the interface between solder alloy and aluminium substrate.But with the Zn content increasing,the amount of dissolution of aluminium substrate becomes lager,the corrosion resistance of solder alloys and soldering joints becomes worse in the NaCl solution.Finally,add Cu alloying element?1⁴wt.%?to Sn-1Al-4Zn solder alloys.When the Cu content is within 1.0 wt.%,with the Cu content increasing,the melting range of solder alloy becomes smaller and the wettabilites on aluminium substrate becomes better.But when the Cu content is more than 1.0 wt.%,the melting range increases and the wettabilities decrease with the Cu content increasing.From microstrure observation,when the Cu content reaches 1.5 wt.%,a layer of Al₂Cu intermetallic compound is formed where is about 10 um far from the interface between the solder alloys and the aluminium substrate.With the further increasing of Cu content,the intermetallic compound layer is more continuous.And owing to the intermetallic compound layer hinders the flow of electrons in electrochemical corrosion,the soldering joints have the better corrosion resistance in the NaCl solution with the increasing of Cu content.