Variation of Electrical Characteristics of EMI Shielding Materials Coated with Ceramic Microspheres

This paper deals with the work done for finding suitable EMI shielding materials to avoid EMI problems in Electrical and Electronics applications. It is well known that all the electronic devices emit electromagnetic rays during their operations. In order to have a smooth functioning of these devices Electromagnetic Interference (EMI) shielding materials are being made use of. Microspheres are one of the many valuable components obtained from coal combustion process. They are inert, light weight, hollow spheres of alumino silicates filled with gas having low density. They possess excellent thermal insulation properties. Microspheres when coated with silver, provides significant Radio Frequency attenuation (reduction of RF interference). The electrical properties like surface resistivity, volume resistivity, capacitance and dissipation factor of EMI shielding materials of Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) have been evaluated before and after coating with these silver coated microspheres.
Evolution and advancement in the field of EMI shielding materials, has led to the development of the number of composite materials. The study is a part of ongoing development work at MTD, CPRI Bangalore.