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US 4,715,894 AGranted
Use of immersion tin and tin alloys as a bonding medium for multilayer circuits
AssigneeTechno Instruments Investments 1983 Ltd.
InventorsAbraham M. Holtzman, Joseph Relis
Life of this patent
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Abstract
A novel immersion tin composition is disclosed containing both thiourea compounds and urea compounds. A method for improving the adhesion of printed circuit boards to one another in a multilayer board and for minimizing or eliminating smear in a multilayer board is also disclosed comprising coating the metal layers of the individual circuit boards with an immersion tin coating prior to laminating them to form a multilayer board.
Claims16
An immersion metal composition comprising:
- (a) a thiourea compound
- (b) a urea compound
- (c) a metal salt
- said metal salt being selected from the group of salts based on the Group IVA metals including tin, Group VIII metals, Group IB metals, Group IIB metals and Group IIIA metals, said urea compound and thiourea compound each being present in an amount sufficient to enable said compositon to function as an immersion composition.
1 more element
Dependencies are inferred from the claim text.