What are Potting Compounds and Their Types?

Within the realm of electronics, potting refers to the manufacturing procedure of filling an electronic assembly with either a solid or gelatinous compound. Potting compounds serve many roles, aiding high voltage assemblies with shock resistance, vibration resistance, mitigation of gaseous phenomena, and protection from moisture, water, and corrosive materials. With the ability to support sensitive components while also protecting the assembly from physical and chemical damage, potting compounds are a crucial part of electronic manufacturing. In this blog, we will discuss some of the most common potting compound types, allowing you to best understand their uses and importance.

While there are a variety of potting compounds that one may use for their particular needs, the most popular are those made from epoxy, silicones, urethanes, and hot melt materials. Epoxy potting compounds in particular are known for their thermal properties, capable of functioning in temperatures ranging from 125°C to 155°C. Such materials are also known for their stability and predictability throughout processing. For their chemical resistance, epoxy potting compounds are well-rounded for most chemicals other than acids.

When using standard rigid epoxies, such compounds are not optimal for high-impact applications unless they have flexibilizers added. As hardened epoxies face the risk of forming small cracks, they also are not as useful for printed circuit boards (PCB) that contain surface mount technologies. Lastly, epoxies should not be used with flexible plastics or those with low surface energy as such compounds are unable to properly wet the plastic.

Silicone potting compounds function at temperatures ranging from  -65°C to 200°C, featuring a Tg of -40°C which makes silicone optimal for SMT assemblies. For their other benefits, silicone potting compounds are capable of providing resistance to solvents, and their construction provides a flexible bond that is capable of being UV cured. Without the use of a primer, silicone potting compounds may face issues with adhesion. Additionally, they are similar to epoxies in the fact that they are unable to properly wet plastics when used with such materials.

Urethane potting compounds operate on a wide range of temperatures, often being suitable for applications with environments that reach upwards of 130°C. Coupled with their various hardness properties and a Tg under -40°C, such potting compounds are well-suitable for PCBs with SMT technology. If increased temperature capabilities are desired, some specialty urethanes are capable of operating at temperatures at 150°C. While urethane potting compounds provide chemical resistance, they are not suitable for full immersion as they will fail. Similar to the aforementioned compound types, urethane is not optimal for use with plastics, regularly being incapable of wetting such materials.

Hot melt potting compounds are fairly simple to use, providing quick setting and efficient gap filling. For maintaining the compound, hot melt materials are easily removable so that a rework may be done. While such materials are not as suitable under high temperatures as compared to other types, they are quite resistant against solvents and are best used for LSE plastics that are typically harder to bond. It is important to know that hot melt potting compounds are quick to set, often only taking around 60 seconds at room temperature.

Due to the various protections and resistances that potting compounds provide, it can be very advantageous to use such materials for the benefit of electronics. At ASAP Aviation Unlimited, we operate as an online distributor of aircraft parts with our unrivaled inventory of new, used, and obsolete items. Take the time to explore our various part and manufacturer catalogs at your leisure, and you may request quotes for your comparisons at any time through the submission of an Instant RFQ form as provided on our website. See why customers choose to steadily rely on ASAP Aviation Unlimited when you initiate the purchasing process with us.


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