Evaluations on the Mixing of the Tin-Bismuth Paste with Sn3ag0.5Cu BGA Components in Terms of Peak Temperature, Time Over Melting and Paste Volume
Authors: Jasbir Bath, Shantanu Joshi, Roberto Segura Company: Koki Solder America Inc. Date Published: 9/22/2019
Abstract: Recently there has been an increase in the evaluation of low temperature lead-free soldering materials such as tin-bismuth. One of the concerns in terms of assembly and reliability is the mixing of the low temperature tin-bismuth paste with higher temperature SnAgCu BGA/CSP components at the typical tin-bismuth paste reflow soldering temperatures in the peak reflow soldering range of 170°C to 190°C. The amount of mixing of the tin-bismuth paste (melting point: 138°C) with higher temperature Sn3Ag0.5Cu BGA/CSP components (melting point: 217°C) can have an effect on the reliability of the component. An evaluation was done to understand the affect of tin-bismuth paste mixing with Sn3Ag0.5Cu BGA components in terms of peak temperature (175°C, 190°C), time above melting(60 sec, 90sec) and solder paste volume. The results are presented in terms of cross-sectional and SEM-EDX analysis.
Tin-bismuth, reflow, mixing, peak temperature, time over melting, paste volume