Influence of Low Ti-Element Additions on The Microstructure, Melting Properties and Creep Behavior of Sn-Ag-Cu Lead Free Solders

Amal Mohamed Yassin,Berlent Khalifa,Reda Ismail Afify

doi:10.24297/jap.v14i3.7834

Abstract

Sn-3.5wt.%Ag-0.5wt.%Cu is one of the alloys considered for replacing SnPb solder alloys in electronic ambiance. In the present study, the effect of minor additions of Ti (0.25, 0.5, 1.0 wt.%) on the microstructure, creep and thermal properties of Sn-3.5wt.%Ag-0.5wt.%Cu lead free solder alloy are investigated by means of scanning electron microscopy (SEM), x-ray diffraction (XRD), creep tests and differential scanning calorimetry (DSC) thermal tests. Results showed that the addition of different wt.% of Ti refined the grain size of the solder alloys. The microstructure parameters obtained from x-ray analysis represented by lattice parameters (a,c), axial ratio (c/a), residual strains (?a/a? & ?c/c?), peak height intensities and crystallite size of some crystallographic planes were found to be sensitive to Ti - additions, applied stresses and working temperatures. The morphological studies using SEM showed refinements of Ag3Sn, Cu6Sn5 and Ti2Sn3 (IMCs) in ?-Sn matrix. Thermal analysis showed that Ti - additions slightly affect melting temperature and pastry range. In terms of creep behavior the addition of 1wt.%Ti gave the highest creep resistance with respect to the others, due to fine dispersion of IMCs. The stress exponents (n) and the activation energies (Q) indicated that the dominant creep mechanism is dislocation climb over all temperature ranges

Highlights

The progress of the electronic devices to reduce mobile thickness and size makes the industrial research looks for new Pb-free solders with good properties is an important issue
The adequate work of adding Ti - element on the creep behavior, microstructure, and thermal properties of SnAgCu lead free solder alloy leads to motivate the investigation of Ti addition
The results show that creep resistance increases with Ti-additions except for Sn-3.5 wt.%Ag-0.5 wt.%Cu-0.5 wt.%Ti (S3); this is due to the decrease of the amount of Cu6Sn5 (IMC) and the increase in the eutectic phase Ag3Sn which is confirmed by x-ray diffraction (XRD) [Fig. 1(a)]

Summary

Introduction

The progress of the electronic devices to reduce mobile thickness and size makes the industrial research looks for new Pb-free solders with good properties is an important issue. Chuang et al [21] have been investigated the effect of adding a small amounts of Ti on the microstructure, hardness and stress-strain properties of SnAgCu solder. The adequate work of adding Ti - element on the creep behavior, microstructure, and thermal properties of SnAgCu lead free solder alloy leads to motivate the investigation of Ti addition.

Results

Conclusion