Experimental investigations on the vapor phase soldering process

Vapor phase soldering (VPS) has been investigated to improve the knowledge about the vapor generation, expansion and condensation processes. Measuring methods for the investigations have been developed and applied. In an experimental VPS system the following parameters have been studied during the heating up and cooling down processes: the temperature distribution in the vessel by measurements using Pt thermistors of ladder arrangement; the temperature distribution in and the heating efficiency of the vapor blanket as function of height by varying the vertical position of the sample with temperature sensors on it; the height of the vapor blanket by a special fiber optic probe; the height of the vapor blanket by applying a floating polymer pillow as vapor level indicator; and the status of the vapor/mist/rain phases by optical inspection of light scattering. The experimental investigations show that the high proportion of the vapor condensates in the upper part of the vessel on the level of the cooling spiral, therefore the vapor is rather in mist phase full with falling down droplets of the condensed fluid, which has a determining effect on the heating efficiency of the medium.