The Effect of Pb Contamination on the Solidification Behavior of Sn-Bi Solders

Published

January 1, 2001

Author(s)

Kil-Won Moon, William J. Boettinger, Ursula R. Kattner, C A. Handwerker, D J. Lee

Abstract

This paper presents experimental results and theoretical calculations to evaluate the effects of Pb contamination on the solidification behavior of Sn-x mass Bi alloys (x = 5, 10, and 58 mass %). The pasty (mushy) range, the type of solidification path, and the fraction of the ternary eutectic are described. The experimental results are obtained from thermal analysis and quantitative metallography, and the solidification calculations are performed using Lever and Scheil assumptions. The experimental results agree with the Scheil calculations. The freezing range of Pb contaminated Sn-Bi solders is greatly increased due to the formation of a ternary eutectic reaction at 95.3 0.5 C. This increase is a lkely cause of porosity in contaminated solder joints. The results provide an example of an analysis method for use in solder alloys in general.

Citation

Journal of Electronic Materials

Volume

30

Issue

No. 1

Pub Type

Journals

Keywords

cooling curve, lead contamination, pasty range, Sn-Bi-Pb, solder, solidification path, ternary eutectic

Citation

Moon, K. , Boettinger, W. , Kattner, U. , Handwerker, C. and Lee, D. (2001), The Effect of Pb Contamination on the Solidification Behavior of Sn-Bi Solders, Journal of Electronic Materials (Accessed October 8, 2025)