Determination and characterization of lead free solder alloys

Abstract

In recent years the development of lead free solders has emerged as one of the key issues in the electronic industries .So far eutectic or near eutectic Sn – Pb alloys have been widely used due to their low melting temperature and good wettability. Sn – Zn solder alloys have been considered as one of the most attractive lead free system that can replace toxic Sn – Pb solder without increasing the soldering temperature. However there are some drawbacks in Sn – Zn lead free system such as poor oxidation resistance, wettability and embrittlement behavior. In order to overcome these drawbacks and to further enhance the properties of Sn- Zn solder a small amount of alloying elements like Bi (Bismuth), Ag (Silver), Al (Aluminium), Cu (Copper), In (Indium), Chromium (Cr), Antimony (Sb), Nickel (Ni), Ge (Germanium) were added. This work aims to investigate the effect of Bi (Bismuth) addition on the microstructure, thermal and mechanical properties of Sn – Zn lead free system. The microstructure of all the solder alloys was investigated using a Scanning electron microscope (SEM). The composition of the solder alloys was determined using Energy dispersive X- ray spectroscopy (EDX). Differential scanning calorimetry (DSC) was done to find out the melting temperature of the alloys. Phase analysis for the alloys was done using X- ray diffraction. Tensile test was performed to find out the mechanical properties of the alloys.