Thermal modeling and experimental techniques for microwave bipolar devices

Many thermal issues facing the microwave bipolar industry are discussed, and the application of experimental and modeling techniques is demonstrated for real microwave devices. The liquid crystal transition method of thermal measurement is shown to be useful for modern bipolar devices because the method can determine temperatures with excellent spatial resolution. Infrared detection, however, generally does not have the necessary resolution for modern small-geometry devices. An experimental technique for determining thermal resistance from device terminal characteristics is shown to be adequate for some applications and packages. Thermal analysis through the use of an exact solution to a three-dimensional model of the semiconductor die is also presented. The modeling technique compares extremely well with detailed measurements by liquid crystal transition on microwave bipolar devices. The application of experimental and analytical thermal characterization is discussed and shown to be important for problems such as device optimization and reliability predictions.<>