Cobar introduced the low-VOC wave-soldering flux 94-QMB, effective in solving a recurrent problem known as solder-ball formation adjacent to plug-in connectors. A great many boards involve a large plug-in connector, comprised of polymers that have a glass transition (GT) temperature that is actually too low to withstand the temperatures of wave soldering. Consequently, when the assembly passes through the wave, the protruding connector pins are heated up beyond the glass transition temperature of polymer. The material softens and the solder adheres to some extent, but upon exiting the solder wave, the malformed mass of solder that is stuck to the connector pins solidifies into one or more solder balls. Additionally, in the connector-pad area, solder balls are often observed adhering to the solder mask. The flux promotes good wetting and eliminating of solder balls. It contains technology that is based on 25% DI-water, a resin system and a matrix of surfactants. Upon its application by spray fluxer or foamer, the material deposits an ultra-thin film on the board that functions as a thermal blanket as well as a solder repellent barrier that protects the polymers against hot solder. The no-clean flux is compatible with conformal coatings, delivering superb soldering performance and environmental friendliness. In spite of the water content, the product can be considered as a drop-in replacement for most alcohol-based formulations.
Share:
