SOLDER JOINT STRENGTH ON COPPER SUBSTRATE UNDER THERMAL AGING CONDITION

Abstract

Failure of solder joints has been a serious reliability problem in microelectronic packages. This phenomenon is more prevail in die-attach industry, particularly in power semiconductor whereby the electronic components is often exposed to high operating temperature. The formation and growth of the intermetallic compound (IMC) layer between the solder and the substrate tends to change accordingly to the operating temperature of the solder joint. A thick IMC layer containing coarse intermetallic compounds may adversely affect the mechanical properties and performance of the solder joint. It is often reasoned that the mechanical integrity of the solder joint is degraded by the inherent brittleness of the IMC layer since cracking can readily occur when the joint is mechanically or thermally stressed. In present work, the shear strength of Pb-2.5Ag-2Sn and Sn-25Ag-10Sb solder joints on copper (Cu) substrate, a widely used material as bond pad in electronic packaging industry is studied. The two types of solder used are of lead-based and lead-free solder that are commonly used in automotive application. The use of shear testing is included in the study to evaluate accelerated thermocycling as a method that has commonly been used for reliability assessment and lifetime prediction. Thermal aging accelerates the development of cracks and structural changes that will eventually weaken a solder joint. © 2006-2016 Asian Research Publishing Network (ARPN).