How to Choose the Right Potting Compound for Electronics
Potting compound protects electronics against moisture, vibration and heat build-up. This guide shows how to select by thermal conductivity, hardness and temperature range, and which chemistry (epoxy, polyurethane, silicone) fits your assembly.
View potting compoundsWhat does a potting compound do and when do I need it?
A potting compound fully encapsulates an electronic assembly and cures into a solid or elastic body. It protects against moisture, dust, vibration and mechanical shock while conducting heat away from components. Unlike a thin conformal coating, potting fills the entire enclosure.
The right choice rests on three core values: thermal conductivity for cooling, hardness for mechanical stress, and temperature range for the environment. Chemistry, viscosity and pot life follow from these.
- Moisture and chemical protection for outdoor and industrial environments.
- Heat removal from power components, LED drivers and power supplies.
- Damping of vibration and shock in automotive and rail electronics.
- Tamper protection and potting of sensors or connectors.
Thermal conductivity, hardness and temperature - what matters?
Thermal conductivity is given in watts per metre-kelvin (W/mK). Unfilled compounds sit around 0.2‑0.3 W/mK, while ceramic-filled thermal compounds reach 1‑3 W/mK. The higher the heat input from components, the higher this value should be.
Hardness is measured in Shore A (soft, elastic) or Shore D (hard). Soft silicones around Shore A 30‑50 absorb thermal expansion and vibration, while hard epoxies around Shore D 80 offer maximum mechanical strength. The temperature range must cover both continuous service temperature and short-term peaks.
Epoxy, polyurethane or silicone - which chemistry?
The three common potting systems differ in hardness, temperature resistance and repairability. Epoxy is hard and highly chemical-resistant, polyurethane stays tough and elastic, and silicone covers the widest temperature range while remaining permanently flexible.
- Epoxy: highest strength and chemical resistance, but rigid and hard to rework.
- Polyurethane: good balance of elasticity and protection, sensitive to moisture during cure.
- Silicone: best temperature range and repairability, often high thermal conductivity as a gap filler.
- Keep the mix ratio (A:B) and pot life exact, and pot bubble-free under vacuum.
Frequently asked questions
What thermal conductivity do I need for an LED driver?
For power electronics such as LED drivers, thermally filled compounds of 1‑2 W/mK are common. With high dissipation in a small space, up to 3 W/mK can help lower the junction temperature.
When should I use silicone instead of epoxy?
Silicone suits high or widely varying temperatures (-60 to +200 °C), where permanent elasticity is needed and the assembly may need to stay repairable. Epoxy is chosen for maximum mechanical strength and tamper protection.
What does Shore hardness mean for potting?
Shore A measures soft, elastic compounds, Shore D hard ones. Soft compounds (Shore A 30‑50) damp vibration and stress, hard ones (Shore D 70‑90) offer mechanical protection. The choice depends on the load on the assembly.
Why pot bubble-free under vacuum?
Air inclusions worsen heat conduction and can expand on heating, stressing components. Vacuum degassing or slow potting with low viscosity prevents bubbles.
Looking for the right potting compound?
We advise on thermal conductivity, hardness and chemistry and supply epoxy, PU and silicone potting compounds including dispensing equipment.
Thermally optimised
Compounds up to 3 W/mK for effective heat removal.
Proven protection
Moisture, chemical and vibration protection up to IP68.
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Values for hardness, Tg and CTE documented.
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Specialists help you select the right material.