Soldering terminology

Not the same as blow holes that occur in molten solder. Voids are formed between PCB layers in multilayer SMT- boards. When pressure rises considerably faster than temperature during the production of multilayer circuit boards, the resin flow becomes too strong, the thickness of the film spirals out of control and heat resistance is lost. In such a case, the slow rate of temperature increase leads to the formation of bubbles between the layers of the PCB. In order to prevent this from happening, a good timing of the heat and pressure supply is essential.