After these decades, I believe that for everyone, especially the electronics company, the circuit board conformal coating is no longer strange, it is not a fast-moving consumer goods, but it is widely used in various electronic products in our lives, but There are Conformal Coating on the circuit board. I have to say that there are still many details that you may not know.
As consumers pay more and more attention to the quality and reliability of products, the electronic products are more intelligent and lighter, and higher requirements are imposed on the processing technology of PCBA. Further deterioration of the ecological environment, dust, corrosion of PCBA. In the past, the conformal coating used only in high-grade products such as military products have gradually expanded to ordinary household appliances, small household appliances, LED lamps and other products. In addition, the rise of emerging industries, the charging of electric vehicles, and the widespread use of drones have further expanded the use of conformal coating. At present, the application of conformal coating on PCBA has become a major trend.
The conformal coating also expose some problems during use, either due to the process or due to the nature of the product itself. Rayming Science and Technology Engineer Hugo, discuss some common problems with everyone.
1. Is it necessary to use conformal coating for all circuit boards?
Answer: Yes, its application can directly increase the protection effect of the circuit board, and the effect is also the fastest. Compared with the bare board, the life of the circuit board of the spray-proof board conformal coating can be extended by about 30%.
2. Is the circuit board conformal coating only moisture-proof, salt-proof and mildew-proof?
Answer: Of course not. moisture proof, salt spray and mildew resistance are just some of the properties of the conformal coating. The protective layer formed after the fixed line can isolate all external materials from the circuit board, that is, the circuit board conformal coating. A series of features such as shock, insulation and dust.
3. Some circuit boards conformal coating have a certain smell, is it poisonous?
Answer: In general, solvent-based conformal coating have a certain pungent odor. They are friendly to the human body and environment within a certain concentration range. Therefore, enterprises must carefully check the MSDS safety instructions during the use process and pay attention to air circulation.
At present, the solvent-free conformal coating is odorless and volatile, but it is more suitable for the brushing process.
7 problems to be noticed on the circuit board conformal coating
The circuit board conformal coating has anti-moisture, anti-salt, anti-static and other three anti-effects, but also has resistance to thermal shock, aging, radiation, ozone corrosion, vibration, flexibility, adhesion and other properties. However, when using the circuit board conformal coating, I must pay attention to a few problems, which can make the conformal coating effect better.
1. Clean and bake the board to remove moisture and water. The dust, moisture and oil on the surface of the object to be coated must be removed first so that it can fully exert its protective effect. Thorough cleaning ensures that corrosive residues are completely removed and the conformal coating adhere well to the surface of the board. Drying conditions: 60 ° C, 10-20 minutes, after being taken out in an oven, hot coated;
2. Apply by brushing method, the brushing area should be larger than the area occupied by the device to ensure that all the devices and pads are covered;
3. When the brush is applied as flat as possible, there should be no dew after brushing, the brush should be flat, and there should be no exposed parts, between 0.1-0.3mm.
4. Before brushing and spraying, ensure that the diluted product is thoroughly stirred and allowed to stand for 2 hours before brushing or spraying. Use a high quality natural fiber brush and gently apply a dip coating at room temperature. If using machinery, the viscosity of the coating should be measured (using a viscosity agent or flow cup) and the viscosity can be adjusted with a diluent.
5. The prototype pcb board assembly should be immersed vertically into the paint slag. 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. Most of the paint residue should flow back from the board to the dipper. TFCF has different coating requirements. The board or component should not be immersed too fast to avoid excessive air bubbles.
6. When using again after dip coating, if there is skin on the surface, remove the epidermis and continue to use.
7. After brushing, lay it on the bracket and prepare to cure. It is necessary to use heating to accelerate the curing of the coating. 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. Three anti-paint is also called PCB electronic circuit board protection oil, coated oil, moisture-proof paint, three anti-coating, waterproof glue, insulating paint, anti-corrosive paint, anti-salt spray paint, dust paint, protective paint, drape paint, three conformal coating glue and so on.
We often see that the metal part of the PCB circuit board is made of patina or is not coated with conformal coating metal copper and steam, oxygen and its chemical reaction.