This paper studies the reliability that CMOS FD-SOI can achieved for mmWave Power Amplifier (PA) applications. The technology opportunities and constraints are also shown. To demonstrate the capability of such technology, a highly rugged power-amplifier for the Ka band radio (26.5- 40GHz) applications implemented in a CMOS 22FDX process is presented. By using design techniques together with an optimized supply voltage reduction, the power amplifier achieves an excellent reliability even under the worst mismatch condition (VSWR) of 7:1. These results validate the capability of the technology for highly reliable power amplifier for mmWave 5G applications.