The polyimide/metal interface was studied by cyclic voltammetry, doubl
e-step chronoamperometry, and electron paramagnetic resonance (EPR) sp
ectroscopy. Experimental results indicated that a zone or a layer of m
etal carboxylate was formed between active metal (such as Al, Ti, or C
r) and PI, but for less active metal such as copper, bonding of copper
(I) ion, and PI radical anion occurred. This PI radical was observed
by EPR spectroscopy. Mixed potential theory has been used here to expl
ain the equilibrium potential of PI-coated metal interfaces.