Predicting junction temperature and MTTF for MMIC devices

摘要

The power rating of monolithic microwave integrated circuits (MMIC) is continuously going up. And the life of an MMIC component due to thermal related failure is directly related to the hot spot temperature on the die. Hence, circuit designers need to carefully design the interface between the MMIC component and the ambient to minimize the thermal related failure or increase the mean-time to failure (MTTF) of MMIC devices. In this article, we provide a simple method for thermal design of a printed circuit board (PCB). More accurate calculation requires performing thermal analysis using any of the finite element software such as ANSYS and COSMOS. Thermal resistance is defined as the ratio of temperature rise to the power dissipated and is expressed in ℃/W. Manufacturers of MMIC components provide the thermal resistance from junction to case (θ_(jc)). Figure 1 shows the cross section of an MMIC component, which contributes to heat rise.