Three proof paint is a specially formulated coating for the protection of circuit boards and their associated equipment from environmental damage. Three proofing lacquer has good resistance to high temperature performance; a layer of transparent protective film after curing, such as in chemical (e.g., fuel, coolant etc.) from damage to circuit vibration, moisture, salt spray, wet and high temperature under the condition of protection. In the circuit board under these conditions may be corrosion, mould growth and short circuit, has superior insulation, moisture-proof, anti leakage, dust-proof, anti-corrosion, anti-aging, anti mildew, loose parts and insulation properties of corona resistance.

Protective paint
Moisture is the most common and destructive factor in the PCB circuit board. Excessive moisture can substantially reduce insulation resistance between conductors, accelerate high speed decomposition, reduce Q values, and corrode conductors. We often see that the metal parts of the PCB circuit boards are made of patina, that is, there is no coating of the three proof paint. The copper metal is combined with water vapor and oxygen to cause the chemical reaction. Coating three - proof paint on printed circuit boards and components can reduce or eliminate the deterioration of electronic products when it may be adversely affected by the operating environment. If the three - proof paint can maintain its function to a satisfactory time, for example, more than the service life of the product, it can be regarded as the purpose of coating.

Three proof paint composition
Acrylic acrylic paint is flexible and provides comprehensive protection. Because it is a single component system, with good adhesion, simple operation, the requirements and conditions of the equipment is not high, convenient construction, high transparency, high brightness, the characteristics of the short operation cycle, so they are easy to use and easy to clean. Some acrylic products to meet military standards, they are dry quickly and not dry, organic solvent available supporting its elimination, so this kind of circuit board conformal coating is one of the most widely use on the market is the most effective product.

Are three poisonous paint poisonous?
Three types of paint is poisonous or not depends on the use of three paint thinner and solvent, if the use of conformal coating of toluene and xylene as diluent, the chemicals are harmful to the human body, if the use of lipids, alcohols and other less harmful. Xylene is moderately toxic and has irritating effects on the eye and upper respiratory tract. It has anesthetic effects on the central nervous system at high concentrations. Although there are many so-called environmental protection three proofing paint on the market, but in actual use, we still need to do a good job of protective measures, wearing gas masks and so on.

There are four kinds of process for the use of three proof paint:
1, brushing - commonly used, can produce smooth coating on the smooth surface of the effect.
2, spray, spray cans use products can be conveniently applied to maintenance and small scale production, suitable for large scale gun production, but the two spraying for the accuracy of the operation requirement is high, and may produce a shadow (not covered with paint three components lower place).
3, automatic dip coating - dip coating ensures full film coverage without causing material waste due to excessive spraying.
4, selective coating - coating accurate and not waste materials, suitable for a large number of film coating, but the coating equipment requirements. The most suitable for large quantities of film coating. Using a set of XYZ programs reduces coverage. When PCB board is painted, there are many connectors which need not be painted. Tape too slowly and tear when there is too much residual glue, can be considered according to the shape, size and position of the connector cover, do a combination, with mounting hole location. Cover the area where no paint is needed.

Operation requirements of three proof paint
1. Clean and dry the board to remove moisture and moisture. The dust, moisture and oil stain on the surface of the object to be painted shall be removed so as to give full play to its protective efficacy. Thorough cleaning ensures that the corrosive residue is completely removed and that the paint is well adhered to the surface of the circuit board. Drying plate conditions: 60 C, 10-20 minutes, in the oven after the removal of hot coating, the effect is better;
2, with brush coating method, brush surface area should be larger than the device to ensure that all cover devices and pads;
3, the brush plate to flat, brush should not dew, brush should be smooth, can not have exposed part of 0.1-0.3mm is appropriate.
4, before brushing and spraying, ensure that the diluted products are fully stirred and placed for 2 hours before brushing or spraying. Use a high quality natural fiber brush and brush gently at room temperature. If the machine is used, the viscosity of the coating should be measured (using a viscosity agent or a flow cup), and the viscosity can be adjusted with a diluent.
5. The circuit board components shall be immersed vertically in the paint lees. Don't immerse the connector. Unless it is carefully covered, the circuit board should be immersed for 1 minutes until the bubble disappears and then slowly take out. A uniform film is formed on the surface of the circuit board. Most coating residues should flow back from the circuit board to the film dipping machine. TFCF has different coating requirements. Circuit boards or components should not be immersed in too fast, so as not to produce excessive bubbles.
6, after the end of the dip coating again use, if the surface has crust phenomenon, remove the epidermis, can continue to use.
7, after brushing, flat on the stent, ready to cure, need to use heating method is coating accelerated curing. If the surface of the coating is uneven or contains bubbles, it should be put in a high temperature furnace for more time at room temperature to allow the solvent to flash out.