Two tank cleaning process using a contaminated cleaning mixture capable of forming an azeotrope
AssigneeImperial Chemical Industries PLC
InventorsJames William Tipping, Bernard Patrick Whim
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Abstract
Contaminated articles, especially printed circuit boards, are cleaned by immersing them in the sump compartment of a cleaning tank containing a boiling mixture of a halogenated hydrocarbon solvent, especially fluorochlorohydrocarbons containing two or three carbon atoms, having a high concentration of an organic solvent, especially isopropyl alcohol, followed by rinsing them in another boiling mixture containing a lower concentration of the organic solvent but at least equal to the organic solvent concentration of the azeotrope.
Claims42
A method of cleaning a contaminated article which comprises contacting the article with a first contaminated liquid mixture which is heated to at least 30.degree. C., removing contamination from the article and accumulating the removed contamination in the first liquid mixture, said first liquid mixture containing a fluorinated hydrocarbon solvent and an organic auxiliary solvent which together can form an azeotrope and wherein the concentration of the auxiliary solvent in the mixture is greater than that of the azeotrope itself, and subsequently rinsing the article with a second liquid mixture containing the fluorinated hydrocarbon solvent and a proportion of the auxiliary solvent which is lower than that contained in the first liquid mixture but at least equal to the auxiliary solvent concentration of the azeotrope.
Dependencies are inferred from the claim text.