Electronic potting glue is a protective glue used for potting electronic components, power supplies, and electronic products. After use, it can provide the best internal stress requirements for electronic devices, ensure that components will not affect each other, and avoid components. Direct exposure to the air can prevent the components from being corroded by the environment, improve the service life of the components, or achieve waterproof, dustproof, and thermal conductivity.

There are usually three kinds of materials for electronic potting glue: epoxy resin, silicone and polyurethane. The electronic potting glue suitable for different components will be different, so how to choose the potting material that needs to be selected?

The following points can be considered:

1. The temperature that needs to be endured after potting (if the temperature is around 100 °C, then epoxy resin and polyurethane can be used, and silicone can withstand high and low temperature of -60 °C ~ 200 °C)
2. Resistance to cold and heat changes (silicon is the best, followed by polyurethane, epoxy resin is the worst)
3. Thermal conductivity (both epoxy resin and silicone have good thermal conductivity, polyurethane is the worst)
4. Electrical and insulating properties (silicon is the best, followed by polyurethane, epoxy resin is the worst)

There are other considerations, such as the internal stress of the components, outdoor use or indoor use, stress conditions, whether flame retardant is required, color requirements, and manual or automatic potting, etc.

The material for making electronic potting glue is usually silicone, because silicone has better resistance to high and low temperature and thermal shock resistance, can withstand thermal shock between -60 °C and 200 °C, and has very strong thermal conductivity. The electrical insulation performance and the corona resistance are better than similar epoxy resin or polyurethane potting compounds.

Both epoxy resin and silicone potting compound have excellent electrical insulation properties after curing, and can be used interchangeably in some occasions, but the two types of potting materials have their own advantages and disadvantages.

Epoxy resin: It has excellent electrical insulation properties at room temperature, and has a low temperature resistance range. It can only work normally at -30°C to 120°C. It has good thermal conductivity and heat dissipation performance, but has poor outdoor UV resistance. The anti-aging performance is poor, the hardness is high, the heat and cold resistance is poor, and the moisture resistance is generally excellent.

Silicone: It has excellent electrical insulation performance at room temperature, high temperature resistance, can work normally at -60 ℃ ~ 200 ℃, has excellent moisture resistance, anti-cold and heat alternating performance, outdoor UV resistance and anti-aging ability , After curing, it is mostly soft and has excellent thermal conductivity and heat dissipation performance.

One-component epoxy encapsulant and two-component epoxy encapsulant with high hardness and strong shear strength. The disadvantage is that the temperature resistance is relatively poor, and the electrical performance is not good. A type of electronic potting glue made of silicone potting glue and silicone rubber includes one-component silicone potting glue and two-component silicone potting glue. Silicone potting compounds are generally soft and elastic. General mechanical strength, good electrical performance, no yellowing, high thermal conductivity, good temperature resistance. Inorganic potting compounds are resistant to high temperatures, generally reaching 500°C-1200°C. Resistant to organic media, the disadvantage is that the hardness is small, the shrinkage rate is large, and it is easy to crack. Polyurethane encapsulant has good bonding performance, insulation performance, small shrinkage rate, and general medium resistance.

Potting compounds do not have common characteristics. In some industries, potting compounds with relatively good performance are required, but the above-mentioned products do not meet the needs of the products. Therefore, the improvement and modification of the potting compound is a better development direction, that is, the use of epoxy or polyurethane to modify the silicone to improve the physical properties on the basis of good electrical properties and good weather resistance.