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Potting compounds for PCBA shall be selected according to component stress sensitivity, operating temperature, thermal conductivity requirements, structural strength, potting clearance and rework demands.

Silicone potting compound SIPA 1850 is suitable for modules with wide temperature range, low stress and frequent thermal cycling;

PUR 1650 and PUR 1680 are recommended for control boards requiring flexibility, vibration resistance and gap filling;

EP 1715 and EP 1780 apply to electronic modules demanding robust structural support, temperature resistance and dimensional stability.

Why is PCBA Potting Required?

PCBA potting refers to filling liquid compound between the PCB and housing, which cures to encapsulate printed circuit boards, solder joints and electronic components.

Its core functions include:

Waterproofing and moisture resistance
Electrical insulation
Component fixation
Vibration and shock mitigation
Protection against salt spray and contaminants
Improved local thermal conduction
Reduced risks of high-voltage creepage and discharge

Compared with conformal coating, potting compounds form much thicker layers and deliver more comprehensive protection, yet they bring higher weight, greater exotherm during curing and increased difficulty for rework.

Recommended Silicone Potting Compounds for PCBA

SIPA 1850AB: Thermally Conductive Silicone Potting Compound

SIPA 1850 is a 1:1 two-part thermally conductive silicone potting material. Its mixed viscosity is approximately 3000 cps. Multiple thermal conductivity grades ranging from 0.8 to 4.0 W/m·K are available, with cured hardness of Shore A 55.

Typical Applications:

1、Automotive electronic controllers;

2、OBC, power supply and inductor modules;

3、Photovoltaic inverters;

4、Energy storage electronic modules;

5、PCBAs exposed to frequent thermal cycling;

6、Components sensitive to mechanical stress.

Cured silicone remains elastic, capable of absorbing thermal displacement between PCBs, copper busbars, plastics and metal housings.

Recommended Polyurethane Potting Compounds for PCBA

PUR 1650AB: Low-Hardness Thermally Conductive Polyurethane

PUR 1650 is a 5:1 low-hardness thermally conductive polyurethane potting material. Its mixed viscosity is roughly 600 cps with thermal conductivity of approx. 1 W/m·K.

Typical Applications:

1、PCBAs with complex structures and narrow gaps;

2、Control boards requiring low-stress protection;

3、Sensors and compact electronic modules;

4、Equipment demanding low-temperature flexibility.

PUR 1680AB: Balanced Flexibility & Mechanical Support

PUR 1680 is a 100:16 thermally conductive polyurethane potting compound. Its mixed viscosity is about 4000 cps and thermal conductivity reaches approx. 0.8 W/m·K.

Typical Applications:

1、Automotive controllers;

2、Current sensors;

3、Industrial power boards;

4、Terminal and connector protection;

5、PCBAs requiring flame retardancy, insulation and vibration resistance.

Recommended Epoxy Potting Compounds for PCBA

EP 1715AB: Thermally Conductive & Flame-Retardant Epoxy Potting Compound

EP 1715 is a 100:15 two-part thermally conductive, flame-retardant epoxy potting material featuring low halogen content. Mixed viscosity is approximately 2500 cps, with thermal conductivity of around 0.7 W/m·K.

Typical Applications：

1、Inductors and magnetic components;

2、Industrial power supplies;

3、Control boards requiring reliable structural support;

4、Modules with strict requirements on insulation and dimensional stability.

EP 1780AB: High-Temperature Resistant Epoxy Potting Compound

EP 1780 is a 100:7 two-part epoxy potting compound characterized by outstanding heat resistance and thermal shock resistance. Its mixed viscosity is roughly 23000 cps and cured hardness is Shore D 85.

Typical Applications：

1、High-temperature electronic modules;

2、Magnetic cores, copper busbars and high-power devices;

3、Structures requiring strong mechanical fixation;

4、Industrial equipment subjected to severe thermal shock.

Elaplus PCBA Potting Compound Selection Chart

Grade	Material System	Suitable Scenarios	Key Selection Criteria
SIPA 1850	Silicone	Automotive electronics, power supplies, energy storage, thermal cycling modules	Wide temperature range, low stress, thermal conductivity
PUR 1650	Polyurethane	Sensitive components, narrow gaps, low-temperature applications	Low viscosity, low hardness
PUR 1680	Polyurethane	Controllers, sensors, terminals	Flexibility, vibration resistance, thermal conductivity
EP 1715	Epoxy	Inductors, power supplies, structural support	Thermally conductive, flame retardant, low halogen
EP 1780	Epoxy	High-temperature & thermal shock modules	High hardness, high temperature resistance

Is Softer Potting Compound Always Better for PCBA?

No.

Soft compounds impose lower stress on components and perform well against vibration and thermal cycling, yet they may lack sufficient structural fixation for large-size components.

Rigid epoxy provides strong support and excellent dimensional stability. Nevertheless, overly thick compound layers or mismatched thermal expansion between different components may raise risks of cracking and interfacial delamination.

Selection shall be determined by internal module structure:

Prioritize low-stress materials for assemblies abundant with chips, sensors and fine bonding wires;
Higher structural strength can be adopted for modules with many inductors, copper busbars and magnetic cores;
Increase thermal conductivity requirements for high-heat-generating units;
Avoid fully non-detachable high-hardness potting if future rework is needed.

How to Eliminate Bubbles during PCBA Potting?

Possible bubble causes:

Air entrapment during mixing of Part A and Part B
Excessively high viscosity hindering natural bubble escape
Closed cavities under PCBs and components
Excessively fast potting speed
Moisture contained on substrates
Too rapid temperature rise during curing

Solutions include optimizing mixing process, vacuum degassing, preheating workpieces, segmented potting and adjusting dispensing paths.

Conclusion on PCBA Potting Compound Selection

For PCBAs sensitive to thermal cycling and mechanical stress, SIPA 1850 is recommended for evaluation.

Choose PUR 1650 if low viscosity and flexible gap filling are required.

Select PUR 1680 for balanced flexibility and mechanical support.

EP 1715 or EP 1780 can be assessed when high structural strength, flame retardancy and dimensional stability are required.

FAQ for PCBA Potting Compounds

What is the difference between PCBA potting compound and PCB conformal coating?

Conformal coating forms a thin protective film, while potting compound fills internal space within modules. Potting compounds deliver superior waterproofing, insulation and mechanical protection.