What is circuit board conformal coating? what’s the effect?
How to make products durable in harsh environments is also an important topic. How do we protect our precision products from these destructive effects? Initially, electronic devices were protected by a method called potting. This is achieved by enclosing the electronics in a custom plastic enclosure that is open at one end, much like an oddly shaped planter. Then fill it with some non-conductive material like acrylic or silicone. This protects the device from the outside environment, but is time-consuming, bulky, heavy and very expensive. Very few people outside of military or industrial customers can actually use it. As electronic devices become smaller and space, weight, time and cost factors become more important, another reinforcement method has become more common: conformal coating, the standard for conformal coating in general It is coating thickness less than 0.21mm.
Conformal coating is the application of materials to coat the surface of a product to protect electronic components from harsh environments. The most common is for moisture. The industries that routinely use conformal coatings are also expanding, but most notably medical, military, marine, automotive and industrial. Conformal coatings are also often used on certain finished products that are often exposed to water or chemical environments, such as dishwashers, washing machines, or any equipment designed to be outdoors, such as security cameras. In addition to protecting electronics, conformal coatings can be used in cosmetic applications such as adding scratch or oxidation resistance to surfaces (clear coats on cars), adding a glossy or slick feel to casings, adding smudges/fingerprints or even altering The optical properties of the lens.
How to maintain the circuit board?
There are different methods of coating circuit boards, each of which requires different coating materials to achieve. First, you need to determine what the purpose of the coating is. Are you protecting PCBA from weather, various oils, mechanical vibration, mold, etc.? Different materials are used for different purposes, and the chemistry used for the coating defines exactly what the coating can achieve. For example, if you want to protect your PCBA from moisture and salt spray, and want to increase resistance to ESD, parylene would be a good choice. However, if the elements on the PCBA are sensitive to heat or vacuum, parylene is not a good choice because both elements are present during the parylene coating process. Acrylic can’t do much electrical, but it will protect your PCBA from moisture and salt spray. It can also be applied in various ways at room temperature.
Classification and Raw Materials of Conformal Coatings
Acrylics are probably the most commonly used paints today. It is also the cheapest material in use. Its main advantages are cost and ease of handling, but it also has some significant disadvantages. The heat softens it, and it is flammable, meaning it can become brittle under certain conditions and, like some molds, susceptible to chemical damage and biological attack. If rework is required, it can be removed using solvents or heat.
Polyurethane is another common coating. Given its slippery hydrophobic and oleophobic properties, it is an excellent coating material. However, these same properties mean it is less likely to stick to other surfaces, and delamination must be mitigated. Rework requires special solvents to remove.
Silicones have unique properties that make them useful coatings where others are not. It is resistant to high temperatures, biologically and chemically inert, and simultaneously hydrophobic and oleophobic. These properties also mean that it is difficult to combine with other materials, and mitigation measures must be taken to prevent delamination. Its rubbery texture and chemical resistance also meant it had to be removed mechanically for rework.
Epoxy resin is an extremely hard material that also has some unique uses. Its rigidity means it can be used as a mechanical reinforcement, but more interestingly it can be used as a safety device. Combining epoxy with other materials, such as crossbars, creates a rigid structure that will destroy itself and adjacent devices if attempted to mechanically separate it from the PCBA. Epoxies are also heat and chemical resistant. Its hardness and setting time are also disadvantageous as it increases processing time and makes rework almost impossible.
Nanocoatings are an emerging solution. As this technology matures, the properties and functionality of nanocoatings are rapidly evolving. A solvent containing suspended nanoparticles is applied to the plate, and the plate is then air-dried or baked in an oven. The oven also melts the nanoparticles into a glass-like substrate. The ultra-thin nature of nanocoatings means they are susceptible to wear but easy to rework.
Post time: Jun-19-2023