The following is a technique for analyzing the area underneath a GaAs integrated circuit or discrete device which may aid in failure analysis. This procedure has been used in the past by the microelectronics community, and it is reviewed here for GaAs monolithic microwave integrated circuits (MMICs) and discrete devices. Because it is a destructive method, we use it in our lab after all other testing is completed. The substrate thickness of the GaAs is ∼4 mils (25 μm).