Electrical Insulation Lifetime of TiO₂/Silicone Gel Nanocomposite in a Needle-plane Electrode

Silicone gel is used for an encapsulating material in power semiconductor modules. However, the voltage endurance of silicone gel is substantially reduced due to the generation of an electrical tree, which refers to a deterioration involving internal cavities that spread similar to trees. In this study, we investigated the electrical insulation lifetime of silicone gel caused by electrical treeing (treeing breakdown lifetime) and the extension of the lifetime due to the addition of TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> nanofillers to the silicone gel. A needle-plane electrode molded by silicone gel nanocomposite or unfilled silicone gel was constructed for evaluating the breakdown caused by electrical treeing. The treeing breakdown lifetimes of silicone gel nanocomposite and unfilled silicone gel were measured when 7 kVrms or and 6 kVrms of AC voltage of 600 Hz was applied. The breakdown tests revealed that silicone gel nanocomposite has a longer lifetime than unfilled silicone gel when the 7 kVrms or and 6 kVrms is applied. These results indicate that the addition of the TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> nanofillers to silicone gel can extend the treeing breakdown lifetime.