MICROSCOPIC AND ELECTROCHEMICAL MONITORING OF THE CATHODIC DEGRADATION OF POLYIMIDE-COATED A1-METALLIZATION

Cathodic degradation of polyimide-coated aluminum metallization on Si substrates has been investigated using electrochemical impedance spect roscopy simultaneously with either light optical or acoustic microscop y. Water uptake by the polyimide can be monitored using the coating ca pacitance and correlates with a change in the polyimide acoustic respo nse. The capacitance of a defect increases with the area degraded by c athodic corrosion due to external cathodic bias.