Investigating of electrochemical migration on low-ag lead-free solder alloys

Among the conditions of high humidity, elevated temperature, and voltage applied, metals and alloys in electronic components and assemblies can cause insulation failures by forming so called dendrites due to the electrochemical migration (ECM) failure phenomenon. This effect causes short-circuit failures of the electronic circuits, which might lead to catastrophic failure. The ECM behavior of lead-free micro-alloyed low Ag content solder alloys (SAC0307 and SAC0807) were compared with common used SAC305, SAC405 and with the traditionally lead-bearing solder alloys: Sn63Pb37 and Sn62Pb36Ag2 as references. In order to carry out the ECM investigations, water drop (WD) tests were made on standard comb patterns in 1 mMol NaCl and 1 mMol Na₂SO₄ solutions as well. The results have shown that the SAC0807 low Ag content micro-alloyed solder alloy could have a relative weak resistance against ECM.