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. The immersion tin composition may also be prepared from a two component system which eliminates or substantially retards the formation of H.sub.2 S in the presence of sulfur containing components.