IGBT器件封装用有机硅凝胶宽频介电特性与温度影响

有机硅凝胶材料作为IGBT器件封装用绝缘材料，在器件的运行工况下，器件承受着重复性导通关断电压，对应频谱宽，且器件损耗将引起温度升高。为了能够准确分析器件内部电场特性，运用频域介电谱技术对有机硅凝胶在宽频、宽温度范围内的介电特性进行研究，利用叉指电极，实现对有机硅凝胶在不同温度下的宽频介电谱测试。采用Cole-Cole介电模型对实验数据进行拟合，并分析温度对Cole-Cole模型特征参量的影响规律。研究结果表明：频率和温度对有机硅凝胶的介电特性均有较大影响，在低频高温下，有机硅凝胶材料相对复介电常数的实部、虚部都显著增加。在所提取的Cole-Cole介电模型的特征参量中，直流电导率σ₀及特征参量Δε₁与温度之间的关系都满足Arrhenius方程，热活化能分别为0.233 eV与0.691 eV；弛豫时间τ₁和τ₂随温度的变化规律有所不同，但在高温时都明显增加。对半导体器件封装用有机硅凝胶材料介电特性的认知可以为器件内部电场分析和绝缘设计提供基础数据支撑。

Broadband Dielectric Properties and Temperature Effects of Silicone Gel for IGBT Device Encapsulation

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.