Base material for flexible printed circuits - with conductive layer bonded by nonflammable polyurethane adhesive

摘要

Base material for flexible printed circuits, consisting of an insulating carrier to which a conductive layer (e.g. copper foil) is bonded using a two-part adhesive contg. (A) 120 pts. polyurethane, (B) 1-200 pts. Sb2O3 and (C) 1-300 pts. organic halogenated flame retardant, with diluent and hardener. Amts. of (A+B) is >=100 pts. Thickness of the adhesive layer is >=20% of that of the carrier. The adhesive layer is non-flammable, and gives good bonding which conforms to the prescribed solder test. Pref. (A) is a reaction product. from a diisocyanate and an aromatic polyester or polyether, contg. excess NCO gps. Pref. quantities are 120 pts. (A), 70 pts. Sb2O3 and 120pts. (C). Thickness of the adhesive layer is e.g. 25% that of the carrier, suitable carrier materials being polyester, polyethylene terephthalate, polyhydantoin or polycarbonate.