抄録
The viscosity of molten Pb-Sn solders and ZnCl2-NH4Cl fluxes were investigated in relation to the solderability. The viscosity was measured with a special designed apparatus using the rotation cylinder method. The solderability was evaluated by both the spreading area of the molten solder on a copper plate and the capillary height of the molten solder penetrated into a gap between two parallel copper plates.
Results obtained are summarized as follows:
(1) A clear correlation was not found between the viscosity of the molten solder and the spreading area of the solder on the copper plate.
(2) The viscosity of flux had an effect on the spreadability of the solder in the temperature range of active flux action, and the lower the viscosity, the larger the spreading area.
(3) The viscosity of the molten solder had an effect on the capillary height of the solder, and hence the lower the viscosity, the higher the capillary height.
(4) Any clear correlation was not found between the viscosity of the molten flux and the capillary height of the molten solder.
