高功率SiC MESFET和GaN HEMT晶体管的热性能指南

　　高功率SiC MESFET和GaN HEMT晶体管的热性能指南

　　这篇文章的目的是提供一个指南，高功率SiC MESFET和GaN HEMT晶体管的热性能的克里宽禁带半导体设备的用户。它解释说，克里的用途来确定其数据表列出的热阻值方法。如同所有的半导体器件，SiC MOSFET和GaN HEMT器件的可靠性是直接依赖于最大运行通道温度。因此，重要的是要在高度的信心下，确定在特定操作模式下的最大通道温度，特别是在CW和散热量大的产品上。

　　热性能的测定

　　Cree公司采用了双礼貌的方法确定其宽禁带半导体晶体管和MMIC产品的热阻。利用红外（IR）技术和有限元分析（FEA）来产生精确的信道情况下的温度差异，从这一θJC（结到外壳的热阻）可以计算

　　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.