HOW DETAILED DESIGN GUIDELINES CAN IMPROVE SOLDERING QUALITY AND REDUCE COSTS IN SELECTIVE THROUGH-HOLE SOLDERING PROCESSES

摘要

For companies producing electronic equipment it is of existential importance to reduce production costs whilst maintaining a consistently high quality level of the manufactured products. Manual repair soldering that is expensive, time-consuming and cost intensive is unacceptable due to the required quality and the requested reproducibility of the whole manufacturing process. In addition, densely populated multilayer boards and miniaturized, high-pin-count, fine-pitch devices cannot be efficiently repaired with high quality. "Hidden costs", such as productivity rates, operator training and damaged assembly costs have to be taken into consideration as well. Special focus has to be set to lead free applications as manual repair soldering processes can cause enormous thermal problems. The target, therefore, has to be a zero-fault soldering process which particularly applies for soldering of single throughhole components after reflow. An appropriate printed circuit board design is of the utmost importance here. The shape of pads and their distance in relation to each other have to be considered, just like the distance between the individual pins or their length. Moreover, by choosing the correct soldering nozzle, one can avoid soldering faults in an automatic selective soldering process. This particularly applies for typical faults such as solder bridges or solder balls. With many practical examples, this paper gives a detailed explanation of the individual points which should be found in the selective soldering process, with regard to the assembly design and solder nozzle technology.