High speed plating of flat planar workpieces

Abstract

An overhead monorail transports racks, in which individual generally flat planar workpieces are suspended, along a path which may provide for several discrete processes in the production line of the circuit boards, and which path includes horizontal linear portion defined in a receptacle adapted to contain an electrolytic solution through which solution the racks and workpieces move between opposed insoluble electrode grills. A pressure manifold is provided at the bottom of the electroplating tank and upstanding nozzle defining towers are adapted to spray electrolyte from immediately behind the above mentioned insoluble electrode grills to continuously impinge upon the surfaces of the circuit board as the boards pass downstream through the tank. Metal to be plated is stored in receptacles behind the pressure manifold nozzle defining towers and the workpiece racks and anode baskets are coupled to a primary source of electrical power such as a rectifier. The workpiece racks and both of the insoluble anode grills are connected to a secondary or auxiliary power source to permit varying the outputs of both rectifiers independently of one another to achieve optimum current densities along the path of movement for these workpieces.