Evaluation of the quality of SMDs according to vacuum vapour phase soldering

In this paper an investigation on vacuum vapour phase soldering processes is presented. The purpose is to identify influencing factors of the solder profile with regard to the quality of the solder joint. For this the vacuum and the temperature profile were systematically varied and the void content, number of solder beads, wetting area and the number of tombstones were measured. An experimental board was designed to represent the effect on chip components, chip carrier and bare die packages in different sizes of each solder profile. Height measurement and X-Ray inspection were applied to gain information about the stand-off and void content. The vacuum pressure and the timing of the pressure variation were found to be the main influencing parameters.