Void-free encapsulation technique for semiconductor devices using silicone gel

Silicone gel is widely used to encapsulate power electronic circuits. Voids in silicone gel have been pointed out as one of the weakest points in insulation where partial discharges (PDs) may easily occur. Degassing process is generally utilized to eliminate voids, but it depends largely on empirical know-how and it is not foolproof. In this paper, an effective encapsulation technique is discussed quantitatively. The theoretical analysis is also experimentally verified. The measured results were in good agreement with the theory. The proposed encapsulation technique reduced the amplitude and number of PDs.