Adhesive bonding and miscellaneous chemical manufacture – Delaminating processes adapted for specified product – Delaminating in preparation for post processing recycling step
Patent
1986-06-18
1987-08-18
Powell, William A.
Adhesive bonding and miscellaneous chemical manufacture
Delaminating processes adapted for specified product
Delaminating in preparation for post processing recycling step
134 3, 134 28, 134 29, 156656, 156664, 156667, 252 793, 252 794, 252 795, C23F 100, B44C 122, C03C 1500, C03C 2506
Patent
active
046875450
ABSTRACT:
A two step process is described for selectively stripping tin or tin-lead alloys from a copper substrate without significant loss of copper from the substrate. In a first step the substrate coated with tin or tin-lead alloy is subjected to the action of a first stripping composition which can be any of those known in the art containing a mixture of an oxidant for the metal or metals of said layer and an acceptor for the cation or cations so oxidized. When the stripping has reached the stage at which a thin film of tin remains on the copper substrate the latter is subjected to the action of a second stripping composition which comprises a mixture of an alkali metal hydroxide and an alkali metal chlorite until the film of tin has been removed and replaced by a film of copper oxide. If desired, the latter can be removed by known means such as treatment with aqueous acid.
The process represents an improvement over known processes in which, in order to remove the last traces of tin from the copper substrate or to remove the film of tin which in some cases is re-deposited from the stripper composition itself, it is necessary to employ stripping conditions so rigorous that significant loss of copper from the substrate takes place.
While the process of the invention is applicable to stripping of tin or tin-lead alloys from copper substrates in a wide variety of contexts, it is of particular application to stripping etch resists from copper substrates after completion of the etching step in formation of a printed circuit board.
REFERENCES:
patent: 2872361 (1959-02-01), Siefen et al.
patent: 4397753 (1983-08-01), Czaja
patent: 4424097 (1984-01-01), Lipka et al.
Letize Raymond A.
Williams Ann S.
MacDermid Incorporated
Powell William A.
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