In this study, temperature-humidity-bias (THB) testing and water droplet (WD) testing have been conducted to study electro-chemical migration (ECM) and dendrite formation across features in aerosol jet printed (AJP) conductor patterns. Test specimen design and testing conditions were guided by industrial standards and related research studies. Time-to-failure (TTF) for AJP printed silver patterns is found to be much smaller than that for conventional copper patterns in THB testing, under identical testing conditions. Furthermore, TTF for dendrite growth between neighboring biased conductors at constant temperature and humidity conditions was found to have a non-monotonic dependence on the electric potential gradient. The dendrite density was found to vary significantly with different applied voltage gradients in both THB testing and WD testing. Those observations can help to guide future investigation and life-prediction modeling of AJP printed electronics subjected to combined temperature, humidity, and voltage stresses.