Process and apparatus for electrolytic deposition of metal layers

US5976341A · kind A · utility

Inventors

• Rolf Schumacher · Marly, CH
• Wolfgang Dahms · Berlin, DE
• Reinhard Schneider · Cadolzburg, DE
• Walter Meyer · Sparks, US
• Helga Meyer · Berlin, DE
• Silke Kaftanski · Winkelhaid, DE
• Petra Fromme · Berlin, DE

Key dates

• Filing date: Apr 22, 1996
• Grant date: Nov 2, 1999
• Expiry date: Apr 22, 2016

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S205/92
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A process and apparatus for electrolytically depositing a uniform metal layer onto a workpiece is provided. The workpiece, for example a circuit board, serves as a cathode. The anode is insoluble and dimensionally stable. Both anode and cathode are immersed in a plating solution contained in an electrolytic container. The solution includes (a) ions of the metal to be deposited on the workpiece, (b) an additive substance for controlling physical-mechanical properties of the metal to be deposited, such as brightness, and (c) an electro-chemically reversible redox couple forming oxidizing compounds when contacting the anode. A metal-ion generator is provided, supplying metal parts of the metal to be deposited onto the workpiece; The plating solution is circulated between the container and the ion generator for maintaining a reaction between the oxidizing compounds and the metal parts for forming metal ions. The plating solution is controllably re-circulated into the container so that a low concentration of the oxidizing compounds is present in the plating solution adjacent to the workpiece.