Conformal coating process requirements

Conformal coating is a specially formulated coating used to protect circuit boards and their associated equipment from the environment attack, thereby increasing and extending their useful life, ensuring safety and reliability. Have the following operational requirements: 

1. Clean and bake the PCB board, remove dust, moisture and oil so that it can fully exert its protective effect. Thorough cleaning ensures that corrosive residues are completely removed and the conformal coating well adhere to the surface of the board. Drying conditions: 60°C, 10-20 minutes, after the removal in the oven, the hot coating effect is better. 

2. Coating by brushing, the brushing area should be larger than the area occupied by the components to ensure that all the components and pads are covered. 

3. The board should be placed as flat as possible when brushing, there should be no dew after brushing. The brush should be flat and there should be no exposed parts. The thickness should be between 0.1-0.3mm. 

4. Thoroughly stirred the conformal coating and stand for 2 hours before brushing or spraying. Use a high quality natural fiber brush and gently brushing at room temperature. If using machinery, the viscosity of the conformal coating should be measured (using a viscosity agent or flow cup) and the viscosity can be adjusted with a diluent. 

5. The components on the PCB board should be immersed vertically into the paint tank. Do not immerse the connector, unless carefully covered, the board should be immersed for 1 minute until the bubble disappears, then slowly take out. A uniform film layer is formed on the surface of the board. The PCB board or component should not be immersed too fast to avoid excessive air bubbles. 

6. After brushing, placed flat on the bracket and ready for curing. It is necessary to heat up the coating to accelerate the curing. If the surface of the coating is uneven or contains air bubbles, it should be allowed to stand at room temperature for more time to solidify in a high temperature furnace to allow the solvent to flash out.