高功率SiC MESFET和GaN HEMT晶體管的熱性能指南

　　這篇文章的目的是提供一個指南，高功率SiC MESFET和GaN HEMT晶體管的熱性能的克里寬禁帶半導體設備的用戶。它解釋說，克里的用途來確定其數據表列出的熱阻值方法。如同所有的半導體器件，SiC MOSFET和GaN HEMT器件的可靠性是直接依賴于最大運行通道溫度。因此，重要的是要在高度的信心下，確定在特定操作模式下的最大通道溫度，特別是在CW和散熱量大的產品上。

　　熱性能的測定

　　Cree公司采用了雙禮貌的方法確定其寬禁帶半導體晶體管和MMIC產品的熱阻。利用紅外（IR）技術和有限元分析（FEA）來產生精確的信道情況下的溫度差異，從這一θJC（結到外殼的熱阻）可以計算

　　IR microscopy is performed using a Quantum Focus Instruments’ Infrascope II IR microscope at 5x magnification （see Figure 1）。 A device under test （DUT） is placed into a suitable test fixture for IR measurement. The test fixture is placed on top of a temperature-controlled heatsink. In order to gain visible access to the die surface， all DUTs must have their lids or plastic encapsulant removed prior to IR imaging. Dependent on the package type， the DUT is either bolted down or soldered into the fixture. For devices that are bolted down， a thin layer of thermal grease is applied to the bottom of the package to ensure that the least amount of contact resistance exists between the package and the fixture. Thermal grease is also used at the interface between the fixture and the heatsink. The fixtures used for IR imaging are modified such that a thermocouple can be placed under the backside of the package to monitor the package case temperature （see Figure 2）。 All IR imaging is performed with the heatsink temperature set to 75°C. A minimum of eight to ten devices from multiple lots are IR scanned to produce a significant amount of data points， which can then be correlated to FEA models.