a printed circuit board assembly employing a solder vent hole adjacent solder filled interconnect vias connecting to a conductive pallet , is disclosed . the solder vent hole allows gases to escape from an otherwise sealed cavity during solder reflow , relieving positive pressure and thereby allowing solder to flow into it . by providing an escape path for trapped air and gases generated during solder paste reflow , the out - gassing pressure and weight of the molten solder is sufficient to allow the solder paste to flow into the cavity .