Abstract: A method for locally applying solder to a set of preselected conductor areas on a printed circuit board without causing thermal damage to adjacent sensitive surface mounted devices and connectors. Before solder is applied, molten solder within a solder reservoir is pumped upwardly through a set of solder wave nozzles so as to clean and preheat the nozzles. The preselected conductor areas on the board are then aligned with the nozzles. At this time, the board is maintained at a height slightly above the nozzles to the extent that the molten solder is prevented from escaping from between the board and the nozzles. A relatively low wave of solder is produced through the nozzles to cause the low wave of solder to contact and preheat the preselected conductor areas on the board. A relatively high wave of solder is then produced through the nozzles to locally solder the preselected conductor areas on the printed circuit board.

Abstract: An apparatus for locally applying solder to a plurality of sets of preselected conductive areas on each printed circuit board to which component leads are joined. The apparatus includes a flux station with flux nozzles, a preheater station, and a wave solder station with solder nozzles, arranged in line to receive and process printed circuit boards. The flux nozzles and the solder nozzles are arranged in a pattern identical to that of the preselected conductive areas on each of the board. A conveyor system is arranged to simultaneously transporting the boards from one station to another.