Potting compound is one of the key material used to protect sensitive and critical electronic components from various threats. Potting compounds provide proper protection under harsh environmental conditions while improving mechanical strength and providing better electrical insulation. Electrical potting compounds are widely used in consumer electronics in a variety of industrial sectors, as well as in areas such as aerospace, automotive, and other industries where electronic components dominate.
What is electrical potting compound
Have you ever opened an electronic device (e.g., ballast) and found out that the entire board or casing is covered with some sort of hard epoxy or resin? This is exactly the purpose of electrical potting compound. The potting compound is a liquid resin that is poured over an electronic board or component in order to fully or partially cover it and provide environmental protection properties, such as heat, shock, insulation, color preservation or corrosion. There are different types of compounds and are applied to electronics according to their end application or environment protection considerations, as discussed below.
What are the different types of electrical potting compound
Depending on the type of intended protection, potting compounds can be made from different materials. For example, urethane (or polyurethane) electronic potting has very high temperature resistance that can withstand temperatures of up to one hundred and twenty degrees Celsius, which make them suitable for high temperature resistant circuits such as ballasts or outdoor power supplies.
On the other hand, a silicone electrical potting compound can be used to preserve light colors due to its non-coloring properties due to its ultraviolet light resistance which is appropriate for LED based boards due to the preservation of the light color. However, it is important to consider the drawback from a specific potting compound, since some might produce heat while curing provoking damage to specific integrated circuits or they might only be applied once and cannot be removed once applied.
What is potting compound used for
As stated before, potting compound exchanges air on the electronics covered by the resin and provides insulation from environmental threats, such as heat, corrosion, flame, and even extend shelf life of the “preserved” item.
In electronics, transformers are highly suitable for the use of electrical potting compound, due to their heating properties and the use of insulation from the magnetic and electrical field, making them a safer application when combined.
What is potting compound made of
As presented above, there are three main types of electronic potting, which consist of epoxy resins, silicones and urethane-based (polyurethanes or PU). There are a series of advantages/applications for each potting compound which will be described in detail below. Remember, the compounds are made of chemical components which properties should make them last ages and resistant to harsh environments, hence the usage of proper environment settings and equipment is always advised, especially with resins that emit gases during their curing process.
What is the potting process for PCB
To have a successful potting for PCBs, it is necessary to place the PCB on a specific casing/enclosure (usually a commonly known as potting box) and start filling the case with the potting compound until it fills the required level. The electrical potting compound will require a short amount of time to up to some minuts (depending on its material base) to cure, and after that it might harden or become a protection for the case and board. There are different king of potting boxes, but most of the time non-epoxy reactive plastic casing is utilized due to its price and simplicity on the assembly process.
What is difference between potting and encapsulation
Although it is not necessary to fully cover the PCB on the potting process (depends on the requirement, the electronic potting can be poured over specific components, also known as PCB encapsulation). The concept of encapsulation can be extrapolated to the fact that potting is the combination of having the case with the potting compound without being removed, while encapsulation considers the removal of the resin/board body from the potting box.
What is electronic components potting material
Depending on the material based of the potting compound, the type of application and utilization will vary as already discussed. While epoxy resins have good chemical and thermal resistance, which make them suitable for SMT applications.
As for PU potting compounds, they are suitable for low temperature resistance and thermal cycling environments. Finally, silicone compounds offer great light endurance properties and thermal cycling environments as well.
How long does potting compound last
The potting compound duration is usually measured with the resistance of a specific potting over several thermal cycles, which provoke thermal shock on the resin particles and might produce cracking. While soft or silicone-based resins are way resistant to cycling, some hard or epoxy-based resins can withstand up to 1500 cycles, which could be translated to many years on the field or environment.
How long does potting compound take to dry
Depending on the curation process the applied resin takes, it can go from ten to thirty second for UV based curation resins to ten to fifteen minutes of total curation time on epoxy potting compounds. It is important to consider that some compounds will emit gas or will heat due to the chemical process of curation, hence the necessary precautions and design considerations for a specific curation/resin process should be taken beforehand. The potting compound preparation is also essential and must consider the right combination of resin elements with de dispensing speed and application temperatures.
How do you remove potting compound
Also known as depotting, the process of removing a potting compound varies again from the base material the resin was formed. On hard resins, a chemical attack of acetone with heat might dissolve partially the resin, but as long as have not cured. In the case that the potting compound cured already, physical means might work (e.g., hammering) but not recommended. It is better not to tamper with since the electronics might get destroyed in the process. It might work utilizing heavy and very toxic and carcinogenic materials such as pyrrolidones and organic acids, but the hazardous process makes it unsuitable to be done without a proper environment and setup.
Conclusion
From miniature personal devices to automated industrial installations, electronics are enabling the world to improve the lives of people around the world and develop products and services that need to be properly protected. Potting compounds are used to protect sensitive and critical electronic components from harsh and climatic environments, vibration, corrosive chemicals, dust, contact with heat and fire, etc.
The potting compound is a liquid resin that is poured over an electronic board or component in order to fully or partially cover it and provide environmental protection properties, such as heat, shock, insulation, color preservation or corrosion.
there are three main types of electronic potting, which consist of epoxy resins, silicones and urethane-based (polyurethanes or PU).
Potting compounds provide proper protection under harsh environmental conditions while improving mechanical strength and providing better electrical insulation.
