In electronics manufacturing and circuit protection, potting compound plays an important role. Especially in PCB circuit board applications, choosing the right sealant can not only improve product reliability, but also effectively protect water vapor, dust, vibration, salt mist, high and low temperature and other complex environments. So, what kind of sealant should you choose for PCB board filling? What is the difference between polyurethane, epoxy resin, and silicone? This article will help you quickly make the right choice!
PCB potting adhesive
1. The core role of PCB sealant
Before the formal introduction of the glue, first clear the main role of sealing glue on the PCB board:
Moisture-proof and waterproof: to prevent moisture and water vapor from penetrating the circuit, to avoid short circuit or oxidation.
Electrical insulation: prevent arc, leakage and other risks, protect the stable work of components.
Heat management: Some sealing adhesives have thermal conductivity to help the components dissipate heat.
Mechanical buffer: Prevents damage to chips and welding points by external shocks or vibrations.
Chemical protection: resistant to corrosive substances such as salt mist, acid alkali, oil pollution.
Different applications for filling glue needs are also different, such as outdoor LED drive power more attention to waterproof UV, industrial power more attention to structural strength and thermal conductivity, these differences determine what kind of glue system to choose.
2, three main filling glue system analysis
- Polyurethane sealant (PUR)
Polyurethane sealant
▶ Features Overview:
Polyurethane sealant is a flexible material system that balances good waterproof, flexibility and adhesion, suitable for circuits that are sensitive to deformation or require a certain amount of flexible buffer protection.
▶ Advantages:
✅ Good soft elasticity, resistant to mechanical shock and thermal expansion stress
✅ High adhesion, suitable for a variety of housing materials (e.g. plastic, metal, fiberglass)
✅ Suitable for room temperature curing, easy construction
✅ Customizable flame retardant grade, thermal conductivity (generally 0.3~0.6 W/m·K)
▶ Typical applications:
Outdoor LED Power Supply, Waterproof Meter, Sensor, Waterproof Connector
Especially suitable for environments with frequent heat expansion and cooling or high humidity
▶ Recommended Products:
PUR 1680 polyurethane sealant
Features: low viscosity, easy to fill, 0.6W thermal conductivity, waterproof grade IP68, high moisture aging resistance, excellent adhesion to plastic / aluminum casing. - Epoxy sealant (EP)
Epoxy sealant
▶ Features Overview:
Epoxy resin sealant with its high mechanical strength, excellent insulation is widely used in PCB board sealing, especially suitable for high reliability, high demanding scenarios, such as automotive electronics, military industrial power supply, communication modules, etc.
▶ Advantages:
✅ High hardness after curing, excellent strength, strong structural stability
✅ Outstanding electrical insulation performance to withstand high voltage and high frequency signals
✅ Chemical corrosion resistance, heat aging resistance, long-term reliability
✅ Increased thermal conductivity (up to 2.0 W/m·K)
▶ Disadvantages to note:
❗ Heat release in the curing process is large, thick layer filling needs to control heat accumulation
❗ More brittle after curing, not suitable for intense vibration environment
▶ Typical applications:
Communication Base Station Board, Automotive ECU Control Module, Power Tool Motherboard, Power Device Package
▶ Recommended Products:
EP 2025 flame retardant epoxy sealant
Features: Flame retardant grade UL94 V-0, high bonding strength, suitable for power circuits or industrial PCB packaging.
EP 1710 High Temperature Epoxy Filling Adhesive
Characteristics: thermal conductivity 1.0W/m·K, high strength, excellent thermal aging, suitable for high-power equipment. - Silicone
Organic silicone sealant
▶ Features Overview:
Silicone sealant with excellent resistance to high and low temperatures and soft buffering properties is the material of choice for extreme environments and sensitive component packaging, especially suitable for outdoor electronics, LED, automotive electronics and sensor applications.
▶ Advantages:
Operates at -60°C to +200°C, some products up to 250°C
Excellent soft elasticity, can buffer thermal expansion and cooling stress
High chemical stability, anti-UV, ozone, moisture
Available in transparent, thermally conductive or flame retardant formulations
▶ Disadvantages to note:
The adhesion is generally less than that of epoxy / polyurethane, but can be improved by coating / dyeing
Cost slightly higher than other systems, suitable for high-end or environmentally demanding products
▶ Typical applications:
LED drive modules, automotive lighting drive boards, outdoor sensors, flexible line protection
▶ Recommended Products:
SIPA 1850 A/B Thermal Conductive Flame Retardant Filling Adhesive
Features: low viscosity, good fluidity, IP67 waterproof, suitable for outdoor products such as LED power supply / meter.
SIPC 1835 A/B Organic Silicone Filling Adhesive
Features: low viscosity, easy machining, high operability, low hardening shrinkage rate, no corrosion, no stress
Choosing sealant, not only the material, but also the choice of reliability
Different PCB application environments determine different requirements for sealant performance. There is no “best” sealant, only the “most suitable” sealant solution.
If your product: Located outdoors, requires strong weather resistance
Pursuit of cost-effective, moderate protection Pursuitof polyurethane sealant
Focus on electrical strength and structural reliability
Welcome to contact us, ELAPLUS can provide you with a full range of electronic sealant products and customized services. Covering a variety of types such as single-component / dual-component, transparent / flame retardant, thermal conductivity / flexibility, widely serving consumer electronics, automotive electronics, industrial control equipment, new energy and other fields.
Tags: pcb sealant · silicone sealant · epoxy sealant · polyurethane sealant
