A STUDY ON MICROSTRUCTURE AND WETTING PROPERTIES OF EUTECTIC SN-PB, SN-ZN AND SN-ZN-BI LEAD-FREE SOLDERS USING WETTING BALANCE INSTRUMENT

R. Mayappan*, A.B. Ismail, Z.A. Ahmad, L.B. Hussain & T. Ariga

  • Ramani Mayappan

Abstract

A STUDY ON MICROSTRUCTURE AND WETTING PROPERTIES OF EUTECTIC SN-PB, SN-ZN AND SN-ZN-BI LEAD-FREE SOLDERS USING WETTING BALANCE INSTRUMENT

Mayappan*, A.B. Ismail1, Z.A. Ahmad1, L.B. Hussain1 & T. Ariga 2

1School of Materials and Minerals Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang, Malaysia

2Department of Material Science, Tokai University, Japan

The microstructure and wetting properties of Sn-40Pb, Sn-9Zn and Sn­8Zn-3Bi solder alloys were investigated. Microstructure of the solders was examined using optical microscope, SEM and EDX. The wetting behaviors of the solder alloys with Cu substrate were studied with wetting balance method at temperature 250°C. The Cu substrate was immersed for 5 mm depth for 5, 10, 20 and 30 seconds. Sn-40Pb solder consists of some Sn-rich phase surrounding the Pb-rich phase in the eutectic matrix. In the case of Sn-9Zn, the system exhibit needle-like structure of Zn-rich phase. For the Sn-8Zn-3Bi system, it has the needle-like structure as well as some Bi segregation towards the surface. For Sn­40Pb and Sn-8Zn-3Bi solder alloys, the wetting force does not improve with increasing dwell time and they have a mean wetting force of 5.5 mN. The Sn-9Zn solder alloy exhibit an increase in wetting force from 5.9 to 6.2 mN for increasing dwell time. On the other hand, the mean wetting time for Sn-82n-3Bi solder is 0.40 seconds compared to 0.52 and 0.53 seconds for Sn-9Zn and Sn-40Pb, respectively. For the flux used, the addition of 3 wt % Bi improves the wetting time but does not improve the wetting force.

'Corresponding author: 6(04)5941010; Fax. 6(04)5941011 E-mail. rasiadi@yahoo.com (Ramani Mayappan)

Published
2015-12-01
Section
Original Research Article