The printed circuit board components of aviation electronic products are composed of various types of printed circuit boards (PCBs), which are extremely important components of aviation electronic equipment. With the continuous development of aviation electronic equipment, the systematization and complexity of printed circuit board components in aviation electronic products are increasing, and the usage environment is becoming increasingly harsh. Due to the combined interference of internal working environment, external natural environment factors such as humidity, salt spray, and mold, there is a risk of signal transmission abnormalities and functional failure in printed circuit board components. In order to reduce or avoid the impact of environmental factors, it is essential to carry out a three proof process treatment after assembly to achieve characteristics such as moisture resistance, salt spray resistance, and mold resistance, and to improve the environmental adaptability and reliability level of printed circuit board components for aviation electronic products.

When the surface tension of the three proof paint is too high, the wetting ability of the PCB board is hindered, causing the contact angle between the three proof paint and the PCB board surface to increase. The three proof paint applied to the surface will shrink, resulting in uneven film thickness, discontinuous edges, unevenness, and poor coverage. Therefore, improving the substrate surface tension of printed circuit board components in aviation electronic products is the fundamental solution to the problem of three proof paint anti wetting defects.

Plasma cleaning technology

Unlike solids, liquids, and gases, plasmas are composed of high-energy and highly active particles such as electrons and ions, which are highly reactive with the surface of solids. Through plasma cleaning, surface molecular level pollutants can be significantly removed, the surface tension can be significantly increased, and the wetting and bonding abilities can be effectively improved. Therefore, it has an increasingly wide application prospect. In the manufacturing process of aviation electronic and electrical products, this technology is widely used in the production of microwave integrated circuits and the assembly of hybrid microcircuit products. Plasma cleaning can remove pollutants from the internal surface of substrates or mixed microcircuit products, enhance surface activity, and significantly improve product quality and reliability

The principle of plasma cleaning includes two levels: one is that the surface is bombarded by plasma, which can form new chemical structures such as active atomic groups; Secondly, plasma can remove surface impurities and etch the surface to a certain extent, increasing surface roughness and increasing the contact area between the surface and the coating layer, resulting in a significant improvement in interfacial bonding strength.

Plasma cleaning can effectively increase the surface tension in the interface parameters of PCB boards, that is, plasma cleaning can effectively improve its surface tension, achieve cleaning and activation of the surface of PCB boards, and thus effectively enhance the wetting ability of the three proof paint on the surface of PCB boards. Therefore, plasma cleaning can be fully applied as a pre-treatment method for printed circuit board components of aviation electronic products before the three proof coating. And the action scale of plasma cleaning is at the ion level, with a surface influence depth of tens of nanometers, far less than 0.1 μ m, which will not cause damage to the solder mask layer and substrate of printed circuit board components in aviation electronic products.

Figure 1 shows the state of water droplets on the surface of printed circuit board components in aviation electronic products before and after plasma cleaning. After plasma cleaning, water droplets are more easily wetted, and a smaller droplet angle can effectively solve the anti wetting defect of the three proof paint on printed circuit board components in aviation electronic products.

Figure 1 Comparison of droplet angles of printed circuit board components for aviation electronic products before and after plasma cleaning

Plasma cleaning is an effective solution for the anti wetting defects that occur in the three anti coating of printed circuit board components in aviation electronic products. By activating the surface of the PCB board with plasma, its surface tension is increased, wetting properties are enhanced, and there is no impact on the electrical performance and appearance of the printed circuit board components in aviation electronic products.