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Potentiostatic Plating from Electroless Baths

IP.com Disclosure Number: IPCOM000091727D
Original Publication Date: 1968-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hall, DW: AUTHOR [+2]

Abstract

This plating technique is carried out in an electroless bath in the presence of a constant potential provided by a potentiostat. A three-electrode system is utilized. One electrode is the work being plated. The second is a reference electrode, 0.1 Molar, 1 Molar or Saturated Calomel. The third is an inert platinum electrode. The potential is maintained at a value which the work assumes with respect to the reference electrode, rest potential, utilized about 2 to 5 minutes after plating starts. A typical value with respect to a Calomel reference electrode can be anywhere in the range of 650 mv to approx. 1300 mv. The actual value depends on pH, bath composition, plating temperature, complexing agents and the valence state of the metal ions.

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Potentiostatic Plating from Electroless Baths

This plating technique is carried out in an electroless bath in the presence of a constant potential provided by a potentiostat. A three-electrode system is utilized. One electrode is the work being plated. The second is a reference electrode, 0.1 Molar, 1 Molar or Saturated Calomel. The third is an inert platinum electrode. The potential is maintained at a value which the work assumes with respect to the reference electrode, rest potential, utilized about 2 to 5 minutes after plating starts. A typical value with respect to a Calomel reference electrode can be anywhere in the range of 650 mv to approx. 1300 mv. The actual value depends on pH, bath composition, plating temperature, complexing agents and the valence state of the metal ions.

Maintaining a constant potential results in a substantially constant deposited metallic film composition. If, for example, where it is desired to deposit nickel- iron films, the potential applied is preset to a value higher than the rest potential, the deposited film is iron-rich compared to a film which is plated in the absence of the controlled potential. Thus, by controlling the potential, the composition of the film is controlled.

Plating can be initialed by activating the surface of the work with palladium or, where palladium activation is not used, by momentarily increasing the potential as soon as the three-electrode system is placed in the bath or by combining the above-menti...