How do conformal coatings work?
Sensitive electronic components are exposed to numerous risks: excessive moisture, electrostatic discharge, and UV radiation. To increase the durability of components, manufacturers use PCB conformal coating. To put it simple this is nothing else than the application of a special conformal coating. What is this process and what are the benefits of specialized PCB coating?
What is a conformal shell?
It is a thin polymer layer applied to components located on a PCB board. The purpose of such a coating is to protect components better against atmospheric phenomena and corrosion. Conformal coating requires that the coating be adapted to the specifics of the equipment. Wrong selection will not provide adequate protection, and will increase the risk of shortcomings. Therefore, those responsible for conformal coating should have extensive experience and specialist knowledge.
How are conformal shells formed?
The key to success is creating a coating tailored to the specific types of tiles. Consider the humidity, the temperatures at which the components will operate, as well as the complete structure of the PCB. Varnishing of plates allows you to protect components against a huge number of risk factors. We will mention here mainly: dust, vibrations, grease, chemicals, dirt, high temperatures, shocks, electrostatic discharges, UV radiation.
Conformal coatings are based on resins. The most commonly used resins are acrylic, epoxy and polyurethane. Less often, however, we will meet silicone, parylene layers and coatings made of fluoropolymer. Certain resins differ in terms of their resistance to individual risk factors, and also have an assigned maximum temperature threshold. Most resins can handle temperatures ranging from 120 to 150 degrees. In the case of components operating at higher temperatures, silicone coatings can be used.
How is PCB varnishing done?
The protective properties of the conformal coating depend largely on the method of application. Painting may be done manually. Then, an important factor is, of course, adequate training of the person responsible for conformal coating. The most effective, however, are the fully automated processes performed by the device. Although the cost of such equipment is quite high, in the long run, it means lower production costs because we eliminate the possibility of error occurrence and we use less coating.
PCBs can be painted in two ways. The first is the spray method, which allows you to evenly distribute the resin, but involves a lot of material loss. The second technique is to dip the tiles into the resin. Here, in turn, unevenness and stains may appear. The shortcomings of both of these methods can be eliminated thanks to automatic painting carried out by a specialized device.