PCB mixtures are resistant to acids, bases, oxidation, hydrolysis, and temperature change. PCBs do not easily break down or degrade, which made them attractive for industries. Being heavier than water it will sink to the bottom of waterways and remain there for milennia until it is stirred up by civil works or bottom feeding animals or flood events. Consequently once polychlorinated biphenyls enter the natural environment in soil and waterways it does not break down. It is a chlorine compound that was formulated to be very stable and long lasting. PCB in any form does not occur in nature as a natural organic compound, ie 100% of all PCB in existence is man made. And for good reason: The ethical dilemma of managing contaminated assets is always a cost versus health and safety of an invisible yet known and highly dangerous carcinogen.
#PCB CONTAMINATION SERIES#
Single-part compounds are cured by thermal or by UV exposure. Epoxy is normally available as a two-component thermosetting mixture. It is easy to apply, but can damage the circuit when being removed. Epoxy (Type ER):Įpoxy offers excellent performance as a conformal coating in harsh environments. Spot repairability (by thermal or soldering iron means) is not recommended as it will result in the emission of toxic gasses (isocyanate). Polyurethane (UR) conformal coating is easy to apply but difficult to remove. Polyurethane (UR) coatings offer excellent protection against the effects of chemicals, humidity, and abrasion. This is the most used conformal coating for PCBs. The acrylic conformal coating is applied by using a hand brush, sprayed, or dipping the board in an acrylic resin coating. Acrylic Conformal Coating:Īcrylic Resins(AR) are preformed acrylic polymers that are dissolved in a solvent and used to coat a PCB surface. Protecting a PCB is important, but the selection of appropriate material is essential. The selection of a particular coating is based on the application of PCB and electronics requirements. They are acrylic, epoxy, urethane, silicone, and paraxylylene.
The thickness of the conformal coating usually varies from 3-8 mil (0.075-0.2 mm).īased on the chemical composition, the conformal coatings are classified into five types. They also provide durable insulation to help reduce thermal and mechanical stress on the components.Ĭonformal coatings are an important part of printed circuit boards and are used in a wide range of industries including aerospace, automotive, military, marine, lighting, consumer electronics and industrial.
A conformal coating ensures the protection against PCB against these types of environmental contaminants and conditions.īy providing protection from contaminants and environmental factors, the conformal coatings prevent corrosion of conductors, solder joints and short circuits. The performance of a PCB can be impacted by many external or environmental factors like moisture, extreme temperature, salt sprays, and chemicals. A conformal coating is a polymeric thin film applied over a PCB surface to protect the board and its components from corrosion and environmental contaminants.