A new epoxy resin for G-10 laminates with improved resistance to ambient degradation

The printed circuit industry is aware that dicyandiamide-cured G-10 laminates degrade on storage, often to the point that they lose their ability to withstand exposure to molten solder. This degradation appears to be related to the degree to which the laminate is protected by copper cladding, i.e., the descending order of stability is (1) clad both sides, (2) clad one side, and (3) unclad. This observation, coupled with the fact that good solder dip properties can sometimes be recovered by giving the laminates a heat treatment, suggests that the degradation is due to an outside factor, possibly the absorption of water.