Measurement of Space Charge Distribution in Epoxy Resin Package at High Temperature under High DC Stress

Space charge accumulation properties were investigated on epoxy resin under high dc stresses at high temperature. Due to the recent improvement in operable temperature of semiconductors, it is required to develop a new insulating material for semiconductor packaging, which exhibit a high insulation performance even at high temperature under the high electric stress. To estimate the insulation performance, it is said that the space charge accumulation is characteristic one of important factors for the evaluation of the materials. Therefore, in this study, the space charge behavior in epoxy resin, that is widely used as a semiconductor packaging material, is evaluated using PEA (Pulsed Electro Acoustic) method at high temperature under high electric field. While there are many demand to know the insulating properties in epoxy resin at relatively high temperature like more than 100 degrees C the ordinary PEA system was applicable to the measurement at temperature from room temperature to about 80 degrees C. Therefore, we improved the PEA system available to the measurement at 100 degrees C. In this report, two types of epoxy plate samples were used: one is made using an amine type curing agent (EP-A) and another is made using acid anhydride curing agent (EP-NH). As a result, it was found that an obvious amount of space charge accumulation was observed in EP-A, while it was not observed in EP-NH even under the dc stress of more than 100 kV/mm at 100 degrees C.