Intermetallic Compound (IMC) Analysis by Using Isothermal Aging Testing on Lead Free Solder

Abstract

Lead free solder has been attracting a lot of attention in the recent years due to elimination of the use of lead in the electronic industry. One of the important behaviour of soldering analysis is Intermetallic Compound (IMC) Analysis. This paper focus on IMC analysis for lead free solders. Isothermal aging tests were carried out on the specimens in order to investigate the effects of aging temperature and time on the growth of intermetallic compound of Sn25Ag10Sb (lead-free solder) on Nickel (Ni) Platting Substrate. After reflow, solder joint specimens were put into a thermal oven and isothermally aged at three temperatures of 200, 225 and 250°C for four different time durations of 1, 5, 10 and 15 hours. Samples were analyzed using metallographic techniques with high optical microscope, scanning electron microscopy (SEM), energy dispersive X-ray (EDX). According to EDX analysis, Ni Sn , Ni Sn , Ni Sn and Ni Sn were present in the Intermetallic Compound (IMC) 3 4 3 2 3 4 microstructure. Result for both solders showed that the higher the aging temperature and time, the thicker the IMCs layer grew. Sn25Ag10Sb on Ni interface shows an obvious IMCs layer formed. It was found that the 1/2 formation of IMCs layer was under diffusion-controlled process and its growth can be expressed as X = kt .. The activation energy for the Ni Sn growth in solid state reaction of Sn25Ag10Sb on Ni were estimated to be 3 4 50.733kJ/mol and 42.869kJ/ mol respectively.