A conformal coating is a 25-200?m (1-8 mils) thick (50?m(1-3 mils) typical) protective membrane (or-coating) that adheres to an assembled PCB by literally 'conforming' to its irregular profile. Electrically insulating with good dielectric resistance, it ensures the operational integrity of the assembly. Its primary function is to protect PCBs used in hostile or harsh operating environments. This includes exposure to moisture, dust, solvents and acid fumes, chemicals and vapours, salt sprays, temperature variations, mechanical vibration, and organic attack (for example from fungus). The particular advantages of conformal coatings can be summarised as follows: 1. Insulating properties allow a reduction in PCB conductor spacing of over 80% 2. Can help eliminate the need for complex, sophisticated enclosures 3. Light weight 4. Completely protect the assembly against chemical and corrosive attack 5. Eliminate potential performance degradation due to environmental hazards 6. Minimise environmental stress on a PCB assembly 7. Inherent flexibility conforms to varied component profiles