Method of removing deposits of tin, lead or tin/lead alloys from copper substrates and compositions for use therein
Patent 4964920 Issued on October 23, 1990. Estimated Expiration Date: 
December 15, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
December 15, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesTin/tin-lead stripping solutions Stripping solution for tin or tin alloys Composition and method for stripping films from printed circuit boards Patent #: 4713144 InventorsAssigneeApplicationNo. 451054 filed on 12/15/1989US Classes:134/3, Including acidic agent134/41, Metal base work, acid treating252/79.4With organic materialExaminersPrimary: Pal, AsokAssistant: Ojan, Ourmazd S. Attorney, Agent or FirmInternational ClassesC23G 001/02C09K 013/06 AbstractA composition for removing a layer of tin, lead or tin/lead alloy from a copper substrate such as a printed circuit board comprises an aqueous solution of nitric acid and ferric acid and also contains anthranilic acid to inhibit the degree of attack on the copper substrate. A surfactant, such as a mixture of cocoamine and an ethoxylated fatty alcohol or a mixture of a phosphate ester and an ethylene oxide/propylene oxide copolymer, may also be present to improve the brightness of the remaining copper. | |
