Effect of Sb Addition on Electromigration in Solder Joints

Abstract

Solder electromigration (EM) is recognized as a potential reliability problem in power modules and high performance processors. Power modules are getting smaller in size and higher in power, which causes the solder joints inside to operate at higher temperatures with higher current densities. The addition of Sb to a Sn-rich solder is known to be an effective way to allow high temperature operation up to 175°C. This study investigates the fundamental EM phenomena of a Cu/Ni-P/Sn-0.7Cu/Ni-P/Cu joint and a Cu/Ni-P/Sn-5Sb-0.7Cu/Ni-P/Cu joint to understand the effect of Sb addition on EM under the condition of 175°C and 50 A/mm². The EM failure occurred at the cathode after disappearance of the initial intermetallic compound (IMC) layer in both cases. The Sb addition can delay the decrease in thickness of the IMC layer; therefore it has the effect of extending the EM lifetime.