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

摘要

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.