Etching a substrate: processes – Nongaseous phase etching of substrate – Etching inorganic substrate
Reexamination Certificate
2005-12-29
2009-08-18
Ahmed, Shamim (Department: 1792)
Etching a substrate: processes
Nongaseous phase etching of substrate
Etching inorganic substrate
C216S041000, C216S083000, C216S103000, C216S104000, C134S003000, C148S247000, C427S140000, C427S142000
Reexamination Certificate
active
07575694
ABSTRACT:
A process for chemically stripping a metallic coating on an external surface of a substrate without attacking an internal surface defined by an internal passage within the substrate. Processing steps include depositing within the internal passage a thermally-decomposable wax having a melting temperature above 75° C. so as to mask the internal surface of the substrate, and then treating the substrate with an aqueous solution containing an acid having the formula HxAF6where A is silicon, germanium, titanium, zirconium, aluminum, or gallium, and x has a value of one to six. The aqueous solution is at a temperature below the melting temperature of the wax and substantially removes the metallic coating from the external surface of the substrate, while the wax is substantially unreactive with the aqueous solution and prevents the aqueous solution from contacting the internal surface of the substrate. Thereafter, the substrate is heated to thermally decompose the wax without producing hazardous byproducts.
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Kool Lawrence Bernard
Rutkowski Stephen Francis
Ahmed Shamim
General Electric Company
Hartman Domenica N. S.
Hartman Gary M.
Hartman & Hartman P.C.
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