Electroplating processes and equipment utilizing a foam electrolyte
AssigneeWestern Electric Company, Inc.
InventorsIvan M. Fletcher, Richard H. Meier
Life of this patent
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Abstract
Improved electroplating processes and equipment, in which an inert gas (21) is mixed with a liquid electrolyte (20) to form a foam (23) of the gas plus electrolyte, which foam is then circulated (arrows A) through an electroplating chamber (30) in which anodes (12) and cathode substrates (10) are mounted so as to plate a metal from the foam electrolyte onto the cathodic surfaces of the substrates. Preferably, the gas is nitrogen or argon and the electrolyte may be any of various conventional plating solutions, such as a potassium gold cyanide solution in a specific example of a gold-plating process described in detail. The foam process provides improvements in uniformity of the thickness of the plated metal and in the surface appearance.
Claims13
An improved electroplating process of the type wherein an article to be plated is mounted in an electroplating cell as a cathode, an anode is mounted in the cell in spaced relationship to the cathode to provide therebetween a passage extending in its end-to-end direction transversely of the spacing between such electrodes, a liquid electrolyte is circulated in the cell between the anode and cathode, and a plating potential is applied between anode and cathode so as to plate a metal from the electrolyte onto a surface of the article, wherein the improvement comprises:
- pumping the liquid electrolyte under pressure into a chamber outside the cell while simultaneously injecting into said liquid in said chamber an inert gas under pressure so that the gas mixed with the liquid in the chamber to form therein a a pressurized mixture of such gas plus such liquid constituted by volume of the mixture from about 8% to about 45% of such gas, forcing such liquid-gas mixture by pressure from the mixing chamber and through fluid conducting means to opening means into said cell adjacent to one end of such passage so as to cause through said passage between said anode and cathode a flow of such liquid-gas mixture impelled to so flow by the pressurization thereof, and simultaneously applying said plating potential so that the metal is plated from such mixture in said passage onto said surface of the article.
Improved electroplating apparatus of the type wherein an article to be plated is mounted in an electroplating cell as a cathode, an anode is mounted in the cell in spaced relationship to the cathode to provide therebetween a passage extending in its end-to-end direction transversely of the spacing between such electrodes, a liquid electrolyte is circulated in the cell between the anode and cathode, and a plating potential is applied between anode and cathode so as to plate a metal from the electrolyte onto a surface of the article, wherein the improvement comprises:
- a mixing chamber outside said cell, pump means for pumping under pressure the liquid electrolyte into the chamber, source means of inert gas under pressure, said source means being coupled to said chamber to introduce such pressurized gas thereinto so that the gas is injected into and, mixes therein with, the pumped liquid to form in such chamber a pressurized mixture of such gas plus such liquid constituted by volume of the mixture of from about 8% to about 45% of such gas, and conduit means for conducting such liquid-gas mixture under force from the pressurization thereof from said chamber to opening means into said cell adjacent to one end of said passage so as to cause through said passage between such anode and cathode a flow of such mixture impelled to so flow by the pressurization thereof while such plating potential is being applied and, thereby, plating of metal from such mixture in such passage onto said surface of the article.
Apparatus for electroplating a plurality of flat rectangular substrates, which comprises:
- an electroplating tank for holding a quantity of a liquid electroyte;
- means for suspending the substrates as cathodes vertically in a central region of the tank in a parallel row of substrates to be plated;
- means for suspending a plurality of flat rectangular anodes vertically in the tank adjacent to the substrates so that each substrate surface to be plated is positioned in predetermined spaced relationship to a facing surface of a companion anode;
- a plating chamber mounted in the central region of the tank and having an open topped rectangular U-shaped cross section with a floor and side walls closely surrounding the substrates and anodes;
- and
- means for forming a foam electrolyte consisting a mixture of an inert gas with the liquid electrolyte and for pumping the foam electrolyte into the bottom of the plating chamber in a region located below the anodes and substrates, from which region the foam is forced upwardly through the chamber and through the spaces between the anodes and substrates so as to plate metal from the foam electrolyte into cathodic areas of the surfaces of the substrates when plating potential is applied between the anodes and the substrates, the chamber being arranged so that the used foam electrolyte spills over the upper ends of the chamber walls above the upper portions of the anodes and substrates and overflows into the surface of the liquid electrolyte in the tank, from which point the inert gas escapes and the liquid electrolyte can be recirculated to the system.
Dependencies are inferred from the claim text.