How to perform thermal characterization measurements with RF drive, using Accel-RF hardware coupled with an infrared camera measurement system
It is a common practice when performing reliability testing on an RF semiconductor product to maintain a constant channel temperature over the course of the test. This type of measurement is useful in predicting product lifetimes and durability in the field. By running a device at an elevated channel temperature, it is possible to extrapolate the expected lifetime of the product at normal operating conditions. In recent years, the industry has moved towards the conclusion that in order to get a truly accurate representation of the durability of the part, these operating conditions should include RF drive.
One issue with using data collected at a certain channel temperature to qualify a product is that calculating a precise and accurate channel temperature is extremely difficult and there is no universally accepted method for doing so. The channel temperature is dependent on the amount of power dissipated in the device, the temperature of the device baseplate, and the thermal resistance of the part. The first two variables are easily determined as they can be measured empirically, but calculating an accurate thermal resistance is more difficult. A common industry-standard method for obtaining the thermal resistance is using a QFI infrared microscope to measure the channel temperature.
If the device operational Lifetest is going to include RF drive during the test, it makes sense for the thermal characterization measurements to take place with RF drive as well.
View our app note on Thermal Imaging Measurement Services for a description of how an Accel-RF Smart Fixture can be used with an infrared camera measurement system to fully characterize the thermal profile of devices under RF drive. Included are details of the test setup and hardware required, and analysis of results that were measured.