A new technique for screening and measuring channel temperature in RF and microwave hybrid circuits

An alternative method for the measurement and screening of the operating channel temperature of a semiconductor device is presented. The specific application described is for screening microwave hybrid circuits using high-power gallium arsenide FETs; however, some wider applications are clearly possible using the technique. The major advantage of this technique over conventional methods is that 100% screening of die attach integrity can be performed on completed hybrid assemblies without any internal modification or rewiring. Most of the equipment required is the same as that already available for evaluating the standard RF parameters of the device. Another advantage of the technique is that devices can be screened under RF conditions, a significant benefit for higher-power class-A-type amplifier circuits. Results so far indicate that the resolution of the system is quite adequate to get good noise-free data on devices operating under normal (rather than artificially stressed) bias conditions