The Conformal Coating was initially only applied to printed circuit boards in the high-tech field (automotive industry, aerospace, and aviation). Due to the increasing use of electronic devices in daily life, consumers are also paying more attention to the quality and reliability of products. The use of Conformal Coating can effectively improve product quality for manufacturers, so it is now widely used in civil and commercial applications.
1.The function of the Conformal Coating:
Three proof painting has good resistance to high and low temperatures. After curing, it forms a transparent protective film, which has superior insulation, moisture resistance, leakage resistance, shock resistance, dust prevention, corrosion resistance, aging resistance, corona resistance, and other properties. In real-world environments such as chemistry, vibration, high dust, salt spray, humidity, and high temperature, circuit boards may experience corrosion, softening, deformation, mold, and other issues, leading to circuit failures. The Conformal Coating is applied to the surface of the circuit board to form a protective film (three proof refers to moisture resistance, salt spray resistance, and mold resistance). In situations such as chemical substances (such as fuel, coolant, etc.), vibration, moisture, salt spray, humidity, and high temperature, circuit boards without the use of three proof paint may be corroded, mold growth, and short circuits may occur, leading to circuit failures. The use of three proof paint can protect the circuit from damage, improve the reliability of the circuit board, increase its safety factor, and ensure its service life. In addition, as the three proof paint can prevent leakage, it allows for higher power and closer spacing between printed boards, thus meeting the purpose of component miniaturization.
2. Process requirements for brushing and applying three proof painting:
1. Before brushing, the dust, moisture, and rosin on the surface of the PCBA Board must be removed to ensure that the three proof paint adheres well to the surface of the circuit board.
2. After the first piece of the product is completed, make a three proof paint spraying fixture according to the document requirements, and focus on confirming that the non coating parts of the components need to be covered with protective covers for protection. When the protective cover fails to provide coverage and protection, high-temperature adhesive tape should be used to stick it on for protection.
3. Put the PCBA into the fixture and cover it with a cover plate, then place it into the three proof paint coating machine and set the limit. Edit the program online based on various SOP parameters.
4. The recommended thickness for brushing is between 0.1 and 0.3mm. If a thicker coating is desired, it can be obtained by applying two thinner layers (the second layer must be allowed to be applied only after the first layer has completely dried).
5. After brushing, place the PCBA into a UV curing furnace to heat and accelerate the curing process.
3.Quality requirements for three proof painting:
1. The surface of the PCB should not have paint flow, dripping, or semi wetting.
2. The three proof painting layer should be flat, bright, and uniform in thickness, protecting the surface of solder pads, adhesive components, or conductors.
3. The surface of the painting layer should not have orange peel, bubbles, pinholes, or ripples.
4. Components that do not require protection cannot be painted with three proof painting.
5. The printed circuit board after the three proof painting should be clean and tidy, without any damage to components.
6. There are no defects or foreign objects such as dirt, fingerprints, ripples, shrinkage holes, dust, etc. on the board and components, and there is no powdering or peeling phenomenon.
The above is an introduction to the coating requirements and applications of the three proof painting. With the development of technology, more and more products have chosen to use the three proof painting, which has many main functions, such as superior insulation, moisture resistance, anti leakage, shock resistance, dust prevention, corrosion resistance, anti-aging, and corona resistance. Especially for military, automotive, aviation and other products and quality assurance. So, while applying the three proof painting to the product, it is necessary to carry out the operation according to the customer’s standards and requirements.
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