US 2007/0184208 A1Published application

Process for preparing metal coatings from liquid solutions utilizing cold plasma

AssigneeAMT Holdings, Inc.

InventorsAshok Sharma, Stephen Conover

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Abstract

A method for depositing metals, metal blends and alloys onto substrate surfaces, including microporous substrates utilizing a plasma operation undertaken at room temperature. In the process, a liquid solution of a monomer or comonomer precursor having a metallic component is utilized to wet the surface of the substrate, with the solvent portion thereafter being removed to leave the substrate surface coated with a dry deposit. The coated substrate is then introduced into a plasma reaction chamber with RF energy being applied across spaced electrodes to create a plasma glow along with the introduction of a plasma supporting gas. The substrate is exposed to the plasma glow for conversion of the precursor to dissociated form to create a deposit consisting essentially of the metallic component in elemental form as a cohesive film on the substrate surface. Preferred metals include such noble metals as platinum, gold and silver, as well as other metals. Preferred precursors include platinum hexafluoro-acetylacetonate, (trimethyl) methylcyclopentadienyl platinum, dimethyl (acetylacetonate) gold, and trimethyl phosphine (hexafluoroacetyl acetonate) silver.

The method of preparing continuous thin metallic films upon porous substrate surfaces which includes the steps of:

(a) selecting a porous substrate having open voids exposed to a surface of said porous substrate, said open voids having a minimum diameter of at least 2.5 angstroms and a minimum depth that is greater than the respective minimum diameter;
(b) selecting a precursor selected from the group consisting of a monomer, a comonomer, and combinations thereof, said precursor having one or more metallic components and dissolving said precursor in a liquid solvent to create a mixture of said precursor in solution;
(c) wetting said surface of said porous substrate with said precursor solution to coat said porous substrate;
(d) removing said liquid solvent from said precursor solution through removal of solvent from said surface to provide a substantially solvent-free residue of said precursor on said porous substrate;
(e) providing a plasma reaction chamber with a pair of spaced apart electrodes therewithin or other suitable mechanism for producing the plasma glow and with said reaction chamber having a configuration for supporting a plasma glow therewithin and for receiving said precursor coated porous substrate;
(f) introducing said precursor coated porous substrate into said reaction chamber;
(g) evacuating the atmosphere from within said reaction chamber and applying RF energy across said electrodes to initiate a plasma glow zone and maintaining said plasma glow with said application of RF energy while simultaneously introducing a plasma supporting gas to said plasma reaction chamber;
and
(h) said plasma glow converting said precursor to dissociated form through separation of said one or more metallic components from said precursor to form a deposit consisting essentially of said one or more metallic components in elemental form as a cohesive film on the surface of said substrate, the combination of the cohesive film on said porous substrate forming a coated substrate media, said coated substrate media allowing fluid transport into and out from said open voids.

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Abstract

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