EFFECT OF ZINC CONTENT AND TEMPERATURE ON COPPER SOLDERABILITY WITH Sn-xZn (x = 4.5; 90; 95 wt.%) ALLOYS

The aim of this study was to determine the effect of temperature and Zn content on the solderability of Cu substrates with liquid Sn-xZn alloys (4.5; 90; 95 wt.% Zn). Solderability tests were carried out by the wetting balance test which allows the measurement of wetting force and wetting time and determination of the size of contact angle. The study was performed at two different temperatures applied to each of the examined alloys, i.e. for Sn-4.5Zn at 230 and 250°C, for Sn-90Zn at 400 and 450°C, and for Sn-95Zn at 410 and 450°C. After the solderability tests, structural analysis was performed on sample cross-sections using optical microscopy and scanning electron microscopy coupled with energy dispersive spectroscopy for chemical analysis. It was found that the temperature increase improves the solderability of each of the systems investigated. With process temperature increased to 450°C for alloys with 90 and 95 wt%. Zn, a complete wetting of the tested Cu substrates was obtained (the value of contact angle θ = 0°).

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