The essence of the “three preventions” in electronic processing is to coat a protective film on the protected surface. The protective effect is related to the coating method and coating process. Spraying basically belongs to the protection of the PCBA surface, while dipping can protect the components. Three anti-paint is a kind of specially formulated paint, used to protect circuit boards and related equipment from environmental erosion, thereby improving and prolonging their service life, ensuring the safety and reliability of use.
“Three defenses” process design requirements:
- (1) Protection of components: immersion treatment or potting for transformers, coils, etc.; solid protective film protection for connectors; special treatment for components.
- (2) Coating thickness: The film thickness is between 0.005mm-0.15mm, and the dry film thickness is 25μm-40μm.
- (3) Surface drying: ventilate for 20-30 minutes after coating to dry the surface. You can use it after drying, but avoid collisions during this process.
- (4) Paint curing: It takes 8-16 hours to cure at room temperature.
- (5) Second drying: After the paint is cured, it can be dried twice to ensure the reliability of the product thickness.
- (6) The minimum distance between component coating and non-coating in PCBA is 3mm.
The “three preventions” mainly improve the anti-corrosion level of PCB-covering exposed Cu, isolating corrosive gases and moisture in the air, as long as it can destroy the vulcanization, electromigration, electrochemical corrosion, and chemical corrosion conditions, the goal can be achieved. Coating the three-proof paint can provide various protections for the circuit board: moisture, mildew, dust, insulation, minimize the growth of dendrites, and release stress.
The core of the “three-proof” process: three-proof paint, craftsmanship and paint film thickness. The effect of “three preventions” depends on the thickness of the paint film. The “three defenses” only delay moisture absorption, but cannot completely prevent moisture. If waterproof, dustproof, etc. are required, potting process should be used.