Robert Bruce Calhoun

US Patent:

58837620, Mar 16, 1999

Filed:

Mar 13, 1997

Appl. No.:

8/818472

Inventors:

Robert B. Calhoun - Cambridge MA
Earl C. Johns - Northboro MA

International Classification:

G11B 5127

US Classification:

360113

Abstract:

An electroplating apparatus and method reduces oxidation of thermodynamically unstable and oxidizable ionic species in an electroplating solution to deposit complex magnetic alloys onto substrates. In one embodiment, the electroplating apparatus comprises an electroplating cell in which oxidation of oxidizable anions and cations is reduced. The cell comprises (i) an anode compartment comprising an anode and anolyte solution; and (ii) a cathode compartment comprising a cathode and catholyte solution containing oxidizable plating anions. A cation-selective semi-permeable membrane separates the anode and cathode compartments. An electrical power supply is used to maintain a voltage across the anode and cathode. Upon application of the voltage to the anode and cathode, transport of the oxidizable plating anions, and to a lesser degree cations, to the anode is substantially blocked by the cation-selective semi-permeable membrane, thereby reducing oxidation of the oxidizable anions and cations at the anode. The concentration of the anolyte and catholyte solutions can be tailored, and an inert gas can be maintained above the solution surface in the cell, to further reduce oxidation of the oxidizable plating ions in the cell.