Measurement of the internal space charge behavior for the study of the electrostatic phenomena

Most polymer dielectric materials can store surface charges, which may accumulate and cause an electrostatic discharge (ESD). This phenomenum has become a serious problem because the electromagnetic noise associated with an ESD damages electronic circuits in various kinds of apparatus. The accumulation of surface charge on a polymer dielectric material is conventionally prevented by using surface-active agents or conductive fillers to reduce the surface resistivity, thus enabling the charge on the polymer to leak away. New anti-ESD polymers, on the other hand, contains polymer solid electrolytes and prevent ESD even though their resistivity is high. Since these polymers have charges in them originally, the measurement of their space charge distribution should be helpful in describing their features. We therefore measured the space charge distribution inside some polymer films by using the newly developed pulsed electroacoustic method and showed that a poly(vinyl chloride) film initially has internal charge and generates an electric field by itself. We found that three kinds of anti-ESD materials using different polymer solid-electrolytes can produce the internal space charge electric fields under DC voltage application, thereby compensating the external electric field. These results suggest that space charge measurement is useful in fundamental research of ESD