Abstract
The surface tension of fluxes and the interface tension between molten Sn and fluxes were measured by the maximum bubble method and the drop weight method, respectively, in the temperature range of 300∼500°. The fluxes used were ZnCl2, SnCl2 and mixtures of ZnCl2 and NH4Cl NaCl, KCl or SnCl2. The results obtained are summarized as follows: (1) The surface tension of SnCl decreased while the surface tension of ZnCl2 increased with rising temperature. (2) The surface tension of mixed fluxes increased as the quantity of the 2nd or the 3rd element added to ZnCl2 increased. (3) The interface tension between Sn and ZnCl2 is expressed by the following equation: σ=730.4−0.564θ; where σ: interface tension, dynes/cm, θ: temperature, °C; (4) In the case of Sn and 2 component fluxes, it may be said that the addition of NH4Cl to ZnCl2 results in a larger decrease of the interface tension than the addition of NaCl, but the addition of SnCl2 shows no effect and the addition of KCl shows a small increase of the interface tension. (5) In the case of Sn and 3 component fluxes, by the addition of the 3rd elements (NaCl, SnCl2) to ZnCl2-NH4Cl, the decreasing effect of the interface tension by the 2nd element (NH4Cl) was lost.
