Abstract: A method and apparatus for transporting work to be processed through a series of work processing stations by moving the work along a path extending past the stations to successive positions along the path opposite the stations, respectively, and at each position extending and retracting the work into and from the respective station for processing of the work therein. The present best mode practice and embodiment of the invention are designed to coat or plate the conductors and thru-holes of printed circuit boards with solder by mounting the circuit boards in rack-like work holders, transporting the work holders in succession from an infeed station to an outfeed station along a path extending over a series of tanks containing liquid baths of acid, rinse solution, flux, solder/oil and final wash, respectively, and extending and retracting each work holder downwardly into and upwardly from each tank to successively clean, rinse, flux, solder coat and wash the circuit boards.

Abstract: Printed circuit boards that may contain through-holes, conductors, connectors, etc. are soldered by covering such boards with liquid solder. During such a process, excess or undesirable solder is typically residual on the surface of such boards, and, more specifically, within the through-holes. By the present system, the printed circuit boards are placed in contact with liquid flux, then with liquid solder and are then removed from contact with the liquid solder and passed between two heat transfer medium spray elements which are fully immersed within the heat transfer medium. Said spray elements direct generally opposing laminar flows, enhanced by a Venturi effect, onto such board thereby sweeping off the undesired solder, clearing the holes, and leaving an optimum thickness solder layer where appropriate. The excess solder removed is collected within the system reservoir to be returned to the solder tank for reuse. A final rinse is provided to remove heat transfer medium from the printed circuit board.