Abstract: Silicone gel materials are used as packaging material for IGBT devices. Under the operating conditions, the devices are subjected to a repetitive on-off voltage which corresponds to the wide spectrum, and the device loss will cause temperature rise. In order to accurately analyze the internal electric field characteristics of the devices, the dielectric properties of silicone gel in a wide temperature range were studied by frequency domain dielectric spectroscopy. The broadband dielectric spectroscopy of silicone gel at different temperatures was achieved by using interdigital electrodes. Then the Cole-Cole dielectric model was adopted to fit the experimental data, and the influence of temperature on the characteristic parameters of the Cole-Cole model was analyzed. The results showed that frequency and temperature have a great influence on the dielectric properties of silicone gel in the frequency domain. At low frequency and high temperature, the real and imaginary parts of the complex permittivity of silicone gel materials increase significantly. In the Cole-Cole dielectric model, the relationship between DC conductivity σ₀, space charge polarization intensity Δε₁ and the temperature are governed by the Arrhenius equation, and the thermal activation energy is 0.233 eV and 0.691 eV, respectively. The relaxation time τ₁ and τ₂ are different at low temperature and increase obviously at high temperature. The recognition of dielectric properties of silicone gel materials for semiconductor device encapsulation can provide basic data support for internal electric field analysis and insulation design of devices.

Key words: silicone gel, broadband dielectric properties, temperature, Cole-Cole model, characteristic parameter