RF long term aging and large signal reliability in 22FDX Wi-Fi Power Amplifier (P A) designs is investigated. Packaged PA operating at 5.4GHz., 3.3V VDD with LDMOS as Common Gate and SLVT as Common Source is stressed under accelerated DC and RF power conditions for +1.5kPOH at TA=25 C. A custom built Power Amplifier Test System (PATS) tool capable of large signal on packaged samples is used for long term stress. Initial RF performance of ~26 dBm., with gain 14~15 is seen before stress. Power sweeps at regular stress intervals were performed to validate PA degradation. Self-heating effect is studied by correlating TA to junction temp TJ using thermal models. Thermal images confirm that higher Pdiss leads to higher TJ. Output power degradation of < 0.5dB is seen at accelerated voltage of 4.2V after + 1.5kPOH which is correlated to voltage swings. Key limiting mechanism for common gate and source devices are identified, demonstrating the viability of CMOS FDSOI technology for 5G applications.