Electrical characteristics of an ACF bond as a function oftemperature and humidity aging

摘要

A commercial Hitachi anisotropic conducting film (ACF) was used toform the electrical interconnection between aluminum pads on a glassplate substrate, and electrolysis tin coated copper pads on a polyimideflexible circuit. These interconnections were aged over 1,400 hours at85° C and 79% relative humidity. Throughout the thermal aging perioda variety of electrical properties were measured. Electrical resistanceof the ACF bonds was monitored in situ providing a continuous record ofthe resistance increase toward failure. The specimens were periodicallybrought back to ambient and dried out to monitor the resistance recoveryand how other electrical properties were affected due to aging. Acontinuous resistance monitoring during the temperature ramp providedthe temperature coefficient of resistance as a function of aging. Theother electrical properties measured at ambient conditions were thevoltage coefficient of resistance, both at low currents and at highcurrents, where self-heating occurred, the magnitude of 1/f noise, andthe thermopower. As will be explained, each of these electricalproperties provides an independent measurement of criticalinterconnection parameters