Corrosion Behavior of Ag/Sn Galvanic Couple at Applied Potential
In practical application,the selective oxidation of Ag3Sn in Sn-Ag-Cu(SAC)solder will take place to form pure Ag,resulting in the formation of Ag/Sn galvanic couple.As development of elec-tronic devices tends to miniature while high performance,the solder joints decrease in size,the in-be-tween gaps become narrower,these factors lead to the increase in the intensity of the local electric field around solder joints.As a consequence,the corrosion behavior of SAC solder may change.In this paper,the corrosion of Ag/Sn galvanic couple under different applied potentials was studied by open-circuit po-tential and potentiodynamic polarization test and bipolar electrochemistry test.The results show that the OCP of Sn was lower than that of Ag.At high applied potential,Sn suffered severe corrosion while the for-mation of AgCl inhibited the dissolution of Ag;at low applied potential,Sn suffered cathodic corrosion.
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