Scaling of Components for Explicit Modelling of Heat Transfer during Vapour Phase Reflow Soldering

In this paper, heat transfer on different surface mounted components is investigated during vapour phase reflow soldering (VPS), where the heat transfer is based on condensation of the heat transfer medium. It is known, that the filmwise condensation differs considerably from more conventional soldering heat transfer mechanisms; our focus was to extend the board level explicit modelling of heat transfer to the range of surface mounted devices (SMDs). The components chosen for investigation ranged from 1206 size to 5040 on the chip-size SMD package scale. Smaller components were omitted from practical reasons. The temperatures of the components were measured with thermocouples lead into the centre. The Biot-numbers for each components were calculated to validate the possibility of explicit modelling. Heat transfer and resulting temperature profiles were calculated according to different modelling approaches. It was found that for smaller components, the modelling approach does not give acceptable precision, however with increasing component dimensions, acceptable results can be achieved.