Investigations on Vapor Phase Soldering Process in an Experimental Soldering Station

摘要

Vapor phase soldering (VPS) has been investigated to improve the knowledge about vapor generation, progression and condensation processes. VPS is an emerging reflow method for electronic assemblies, in terms of efficiency and quality. An experimental VPS station was developed for measurements and investigations with applying components and solders of various materials. The flexibility of the system allows custom heat profiling and temperature control. New measuring methods for the investigations have been developed and applied. In the experimental VPS system the following parameters have been studied during the heating up and cooling down processes: the vertical temperature distribution in the tank using Pt500 sensor ladder arrangement combined with data logging; the time and power required to set stationary temperatures inside the tank; the height of the vapor blanket by a custom built fiber optic probe; the height of the vapor blanket by applying a floating polymer pillow as vapor level indicator; the status of the vapor/mist/rain phases by basic optical inspection of light scattering; 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 experimental investigations show that high proportion of the vapor condensates in the space on the level of the cooling tube in the upper part of the tank, therefore the vapor is rather in mist phase with falling drops of the condensed fluid, which has an effect on the heating efficiency of the medium.