The effect of multiple reflow on intermetallic layer of Sn- 4.0AgCu/Cu by using microwave and reflow soldering

Soldering method is a general trend in demand that can be used to analyse different process parameter and their relationship in faster and easier way. Different soldering methods will influence the growth of intermetallic layer. This study investigates the effect of multiple reflow on intermetallic layer of Sn-4.0Ag-0.5Cu with diameter 700 μm solder size and Cu substrate by using microwave soldering. As comparison, reflow soldering was conducted. The material characteristic was characterised by using optical microscope, emission scanning (SEM) and energy dispersive X-ray analysis (EDX). The results revealed that only Cu6Sn5 intermetallic compound (IMC) was formed on solder joint. Meanwhile, Cu3Sn layer was detected after second and third reflow. The results also indicated that the soldering method could influence the IMC growth, where the microwave soldering produced a thinner IMC layer than reflow soldering. Besides, the morphology of IMC was observed as smaller circle bumps and scallop shapes. Moreover, the grain sizes of IMC for reflow soldering presented a larger, denser and rounder compared to microwave soldering.