Spectroscopic studies of the chemical properties of thin metal films on poly(ether imide)

X-ray photoelectron spectroscopy studies were conducted on thin films of copper and nichrome (80:20 Ni:Cr) on neat poly(ether imide) (PEI) substrates. Evaporated copper thin films reacted mildly with PEI and formed metal carbides and oxides at the copper - PEI interface. In contrast, the chromium component of the nichrome alloy reacted strongly with PEI to generate a distribution of chromium oxides, nitrides, and carbides. However, the nickel component of nichrome exhibited little reactivity with the resin. Differences in the reactivities of metal thin films on PEI can be correlated to the heats of formation of the corresponding metal carbides, oxides, and nitrides. This information provides key insights into metals for use as adhesion promoters on printed circuit boards and molded circuits containing PEI.