A method of producing a multilayer circuit board comprising a core substrate and a plurality of layers of wiring lines on both sides of the core substrate with an insulation layer being interposed therebetween; the layers of wiring lines on both sides being interconnected by conducting members provided on the inside walls of through holes going through the core substrate, and the interposed insulation layer. The method further comprising, wiring lines with an upper layer of wiring lines wherein the conducting member on the inside wall of the through hole and the via are formed in separate steps. The method can provide a multilayer circuit board which can advantageously be used to mount a chip or device thereon having an increased number of electrodes or terminals.

A method of electroplating circuit board substrate having a high density, multi-trace circuit pattern formed on at least one major surface of an insulative substrate, without requiring formation and at least partial removal of a large plurality of electrically conductive tie bars contacting each of the circuit traces for supplying electroplating potential/current, comprises providing the at least one major surface with a single tie bar having at least a pair of laterally extending arms in simultaneous electrical contact with an end of each trace. Portions of the tie bar extension arms are selectively removed after completion of electroplating, e.g., by laser drilling or plasma etching, to electrically separate each of the circuit traces from the tie bar. According to an embodiment of the invention, electroplating is simultaneously performed on a dual-sided substrate including electrically interconnected circuit patterns formed on opposite sides thereof. The invention enjoys particular utility in the fabrication of ball grid array (BGA) semiconductor device packages.

In order to regulate the metal ion concentration in an electrolyte fluid serving to electrolytically deposit metal and additionally containing substances of an electrochemically reversible redox system, it has been known in the art to conduct at least one portion of the electrolyte fluid through one auxiliary cell provided with one insoluble auxiliary anode and at least one auxiliary cathode, a current being conducted between them by applying a voltage. Accordingly, excess quantities of the oxidized substances of the redox system are reduced at the auxiliary cathode, the formation of ions of the metal to be deposited being reduced as a result thereof. Starting from this prior art, the present invention relates to using pieces of the metal to be deposited as an auxiliary cathode.

The invention relates to a method and an apparatus for producing an electrode coating. The fundamental idea of the invention is to regulate in a time-defined manner at any instant during an electrolytic deposition process the concentration of the electrolyte constituents and additives in that in the electrolytic bath are provided additional electrodes, through which specific electrolyte constituents and/or additives can be taken up and/or delivered in time-controlled manner.

A process for copper-plating a wafer which comprises electroplating a semiconductor wafer with an electrode comprising a corrosion-resistant metal substrate and a coat mainly composed of iridium oxide provided on the substrate as an anode and the wafer as a cathode in a solution containing copper ion. The anode is preferably an insoluble electrode comprising a corrosion-resistant metal substrate and a coat mainly composed of iridium oxide and further containing a metal or metal oxide selected from platinum, tantalum, titanium, niobium and oxides of these metals provided on the substrate. A neutral membrane or ion exchange membrane may be interposed between the anode and the cathode as a separating membrane.