Electrochemical behaviour of lead-free Sn-0.7Cu-xIn solders alloys in 3.5 wt% NaCl solution

Various electronic equipment has been exposed to a very harsh atmospheric condition that results in corrosion of the solders inside it. The type of corrosion, in most cases, is electrochemical. The lead-free solders are mostly preferred as the solder. Electrochemical corrosion behaviour of lead-free solder Sn-0.7Cu alloys with a variation of indium of x = 0-3 wt% was studied in an air-saturated aqueous solution 3.5 wt% NaCl at room temperature. The potentiodynamic polarization test shows that corrosion resistance improves with In content. The addition of indium refines the microstructure and improve Sn-0.7Cu solder alloys' corrosion resistance by lowering the current density (I-corr), resulting in high resistance of the passive layer formed. XRD analysis shows that the composition of corrosion products also changed with indium content variation, phases such as Sn3O(OH)(2)Cl-2, and oxides and chlorides of Sn were formed. Electrochemical impedance spectroscopy analysis shows that Indium addition changes the behaviour of the electrochemical interface from charge transfer to diffusion control.