Electrical characterization of epoxy-based molding compounds for next generation HV ICs in presence of moisture

The effects of moisture on the electrical properties of epoxy molding compounds containing high quantities of silica filler microparticles have been investigated by means of dielectric spectroscopy, steady-state conductivity and pulsed electro-acoustic space charge measurements. It has been shown that the presence of water at the filler/epoxy interfacial areas affects the low-frequency dielectric response of the materials and significantly increases their electrical conductivity, especially at higher temperatures. In addition, in presence of moisture, space charge measurements have shown the accumulation of heterocharges which significantly increase the electric field at the electrodes. These aspects are of primary importance, as the electrical properties of the encapsulation materials strongly influence the space charge distribution in high voltage devices.