Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Patent
1990-10-15
1992-03-17
Valentine, Donald R.
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
20412925, 2041292, 204212, 204228, 204231, 204237, 204238, 204239, 204240, 204252, 204DIG7, C25F 302, C25F 316, C25F 700
Patent
active
050965506
ABSTRACT:
In an electropolishing or electrolytic etching apparatus the anode is separated from the cathode to prevent bubble transport to the anode and to produce a uniform current distribution at the anode by means of a solid nonconducting anode-cathode barrier. The anode extends into the top of the barrier and the cathode is outside the barrier. A virtual cathode hole formed in the bottom of the barrier below the level of the cathode permits current flow while preventing bubble transport. The anode is rotatable and oriented horizontally facing down. An extended anode is formed by mounting the workpiece in a holder which extends the electropolishing or etching area beyond the edge of the workpiece to reduce edge effects at the workpiece. A reference electrode controls cell voltage. Endpoint detection and current shut-off stop polishing. Spatially uniform polishing or etching can be rapidly performed.
REFERENCES:
patent: 3692639 (1972-09-01), Delmousos
patent: 3703458 (1972-11-01), Read et al.
patent: 3849270 (1974-11-01), Takagi et al.
patent: 4073708 (1978-02-01), Hicks, Jr.
patent: 4238310 (1980-12-01), Eckler et al.
patent: 4971676 (1990-11-01), Doue et al.
"Electropolishing of Vertical Copper Cylinders in Phosphoric Acid Under Natural Convention Conditions" by G. H. Sedahmed et al., Surface Technology, 11, pp. 67-71 (1980).
"Electropolishing" article in McGraw-Hill Encyclopedia of Science & Technology, pp. 810-811 (1982).
Bernhardt Anthony F.
Contolini Robert J.
Mayer Steven T.
Carnahan L. E.
Moser William R.
Sartorio Henry P.
The United States of America as represented by the United States
Valentine Donald R.
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