Space charge observation in aramid/epoxy insulations under DC electric fields

With the progress of printed circuit technology, the reliability of bulk insulation has become important, as well as that of surface insulation, particularly in multilayer boards and embedded boards. We observed the space charge behavior of various insulating materials used in printed circuit boards, and found that internal charges move in aramid/epoxy specimens under dc electric fields. The electric field near the surface of the specimen, therefore, was increased to have more than twice the strength of the average applied field. The space charge profile was influenced by the internal structure, and its formation was accelerated by the increase of temperature. Since the space charge profile affects the internal electric field distribution, the internal charge behavior should be examined with respect to the design of the insulation of a printed circuit board.