Applying a conformal coating to a PCB (Printed Circuit Board) is often recommended for increased reliability and longevity. Conformal coatings protect PCBs from environmental elements like moisture, dust, chemicals, and temperature fluctuations, minimizing the risk of corrosion and electrical failures. The necessity depends on the PCB's application and the environment it operates in. High-humidity, corrosive, or challenging conditions make conformal coating essential, while in controlled environments, it may be optional. Ultimately, the decision considers the specific requirements of the application and the potential impact of environmental factors on the PCB's performance and lifespan.