Copper deposition onto polyetherimide: Interface composition and adhesion

Abstract

The chemical composition and adhesion of the interface between copper (applied via an electroless bath or by vacuum evaporation) and polyetherimide substrates are investigated. Electroless copper deposition requires a chemical pretreatment to ensure final adhesion values of 180–220 g/mm, whereas comparable adhesion is obtained for evaporated copper without pretreatment. Both metallization methods require a postdeposition heat treatment to maximize the copper/polyetherimide adhesion. The interface side of the metal deposits are exposed by a substrate dissolution technique and analyzed using x-ray photoelectron spectroscopy. A thin (∼30 Å) insoluble polymer layer remains which is believed to chemically interact with the metal. In addition, interfacial oxidation of the metal deposit increases with the application of the heat treatment. The role of this interfacial chemistry on copper/polyetherimide adhesion is discussed.