The difference between epoxy resin, silicone, and polyurethane sealant and the working principle of electronic sealant

Sealing adhesive is mainly used for bonding, sealing, potting, and coating protection of electronic components. In terms of materials, there are currently three most commonly used types, namely epoxy resin sealant, silicone resin sealant, and polyurethane sealant.

　　Epoxy resin sealantIt is generally composed of epoxy resin, curing agent, and filler, and can be cured at room temperature or medium temperature. Advantages: Strong adhesion, high hardness, corrosion resistance, good insulation performance, easy operation during use, and curing is generally only affected by temperature. Disadvantages: Poor resistance to alternating cold and heat, easy to crack after being subjected to cold and heat shock, high hardness and brittleness of the solidified gel, and easy to strain electronic components.

Organic silicone sealant is mainly composed of organic silicone resin, curing agent, and filler. Advantages: high and low temperature resistance, strong aging resistance, good weather resistance, good impact resistance, can be used in a wide temperature range, has excellent electrical performance, non corrosive to electronic components, easy to repair, can be cured at room temperature or heating, good self foaming, easy to use, and has excellent waterproof and seismic capacity. Disadvantage: Additive formed organic silicone generally has poor adhesion. Scope of application: Suitable for encapsulating various electronic components that work in harsh environments.

The main components of polyurethane sealant are polyphenylene diisocyanate and polyether polyol, which crosslink and solidify under the action of a catalyst to form a high polymer. The bonding performance of polyurethane sealant is second only to epoxy sealant, but its hardness can be changed by adjusting the content of diisocyanate and polyether polyol, with a wide range of choices. Advantages: Excellent low-temperature resistance, good adhesion, easy control of curing time, and relatively affordable price. Disadvantages: Poor high temperature resistance, prone to foaming during curing, generally requiring machine sealing, not suitable for manual sealing.

With the vigorous development of the electronics industry, people pay more attention to the stability of products and have more stringent requirements for the weather resistance of electronic products. Therefore, more and more electronic products need to be sealed. Sealed electronic products can enhance their waterproof, seismic, and heat dissipation capabilities, protect them from natural environmental erosion, and extend their service life.

　　Electronic sealing adhesiveIt is a liquid adhesive poured onto electronic components, which can provide excellent heat dissipation and flame retardant performance for electronic components, and effectively improve the seismic and moisture resistance of electronic components, ensuring their stability in use.

So what performance requirements does an electronic potting adhesive suitable for electronic components need to meet?

1. Strong electrical insulation capability, which can effectively improve the insulation between internal components and circuits after encapsulation;

2. It has hydrophobic properties and can improve the moisture resistance of electronic components after encapsulation;

3. Having excellent thermal conductivity, it can effectively improve the heat dissipation capacity of electronic products after encapsulation;

4. Has excellent weather resistance and salt spray resistance, ensuring that electronic components are not corroded by natural environments;

5. Colloids have no corrosive effect on electronic components;

6. The solidified colloid will not undergo deformation even after mechanical processing;

7. Strong resistance to cold and hot changes, even when subjected to cold and hot changes between -60 ℃ and 200 ℃, the colloid can still maintain elasticity and not crack;

8. It can be cured at room temperature or by heating.