Thermally Conductive Potting Encapsulant and Thermally Grease: What’s the Difference

When selecting thermal interface materials for your products, you will find that thermal grease and thermally conductive potting encapsulants are both paste-like thermal interface materials. They are both used to facilitate more efficient heat dissipation in electronics, industrial equipment, automotive energy systems, and similar applications. Do you find it difficult to distinguish between them and feel perplexed when making a choice? Continue reading, as this article can provide you with more information about them.

What is the Thermally Grease?

Thermal grease (or thermal paste) is a paste-like thermal interface material featured by an extremely low bond line thickness. It comes in types such as silicone-based thermal grease and non-silicone-based thermal grease, which are manufactured by incorporating highly thermally conductive materials into silicone oil or silicone-free polymer-based inorganic oil. It typically has a higher thermal conductivity than thermally conductive potting encapsulants. When applying thermal grease, you need to use it between the heating element and the heat sink to increase the thermal contact area and minimise voids, thereby achieving superior heat dissipation efficiency.

What is the Thermally Conductive Potting Encapsulant?

Thermally conductive potting encapsulants are another type of thermal interface material that aids in achieving higher heat dissipation efficiency, yet they are also used for encapsulating components to function as an environmental sealing option. Unlike thermal grease, they are not applied as an interface material between the heat-generating component and the heat sink. Instead, they are poured into the entire housing containing the heat-generating component. Furthermore, they should be cured at room temperature or under heat with a platinum curing agent, forming a solid protective layer with protective and insulating properties. So if your product is mandatory to meet IP67/68 level of sealing protection and work in the low-to-middle range of powers, thermal pottings are one of your candidate solutions.

Thermally Conductive Potting Encapsulant and Thermally Grease: Function

Function of Thermally Conductive Potting Encapsulant

• Heat Transfer: Thermally conductive potting encapsulant thoroughly fills and makes contact with the area housing the heat-generating components. They efficiently dissipate the heat produced during operation through their high thermal conductivity. This maintains the device’s temperature within its optimal operating range, thereby maximising performance and minimising the risk of damage.
• Bonding: While exhibiting low viscosity in its paste form, thermally conductive potting encapsulant achieves outstanding robust bonding upon full cure. All the electronic components are held together inside the cured compound. In terms of the chemistry of different types of potting options, the silicone and polyurethane pottings are in lower Shore hardness and their inner stress is less while exposed to ever-changing temperature conditions. As for the epoxy version, it exhibits very outstanding bonding strength over the other two categories, but it’s very hard and might cause failures to the components due to its higher CTE (Coefficient of Thermal Expansion), leading to some crack issues in some cases.
• Protection: After curing, thermally conductive potting encapsulant transforms into a high-hardness solid shell (approximately 60-90 Shore OO), delivering superior mechanical strength and sealing performance for your components. On one hand, it shields internal components from vibration, impact, and similar stresses, enhancing operational reliability. On the other hand, it protects against chemical corrosion, dust, moisture, high temperatures, and other hazards, extending your component’s lifespan.
• Insulation: Typically formulated from insulating materials, thermal conductive potting encapsulant enables safe encapsulation of various electronic components without hurt circuit integrity, delivering enhanced safety.
• Recyclability: With the increasing trends and demands of Carbon Emission regulations, the recyclability is becoming more outstanding among different clients and applications. especially for battery packs, like ESS, EV battery packs and many others. With this concern, our polyurethane option could be a perfect match to be aligned with this regulation, as it can be removed from the cured structure with more ease in operation.

Function of Thermally Grease

• Heat Transfer: Thermal grease fills all surface irregularities between heat-generating components and heat sinks, displacing air within voids to maximise thermal transfer efficiency for you. It typically offers higher thermal conductivity and extremely low interfacial thermal resistance of 0.002°C-in2/W compared to thermally conductive potting encapsulant, making it suitable for your applications with high thermal load requirements.
• Insulation: Thermal grease also has excellent insulating properties, enabling safe use within electrical circuits without risk of short circuits. Due to its typical minimal BLT as expected, its insulation will be degraded over time, but thermal potting will remain the same performance with its crosslinked polymer base
• Protection: Benefiting from high elasticity, thermal grease filling the gap between components and housings (or heat sinks) can absorb and cushion vibrations and impacts to a certain extent. However, its protective capabilities fall short of those offered by thermally conductive potting encapsulants.

Thermally Conductive Potting Encapsulant and Thermally Grease: Composition

Composition of Thermally Conductive Potting Encapsulant

Thermal conductive potting encapsulants are also manufactured by incorporating thermally conductive materials into base polymers, primarily utilising substrates such as silicone, epoxy resin, and polyurethane. Silicone materials offer high elasticity but are unsuitable for projects sensitive to silicone. Epoxy-based compounds have exceptional mechanical strength, bonding strength, and chemical resistance, though they struggle under significant stress. Polyurethane-based compounds are widely used because they combine high viscosity and toughness. All require curing during application and provide excellent protection for your components against damage.

Composition of Thermally Grease

Thermal pastes primarily have silicone-based and non-silicone variants. Silicone-based thermal pastes are made by incorporating highly thermally conductive materials(such as boron nitride, aluminium oxide, diamond fillers, etc.) into silicone compounds, thereby offering you superior flowability and high-temperature resistance. To ensure the safe operation of silicon-sensitive components and avoid harm from silicone oil or vapour migration, non-silicone thermal pastes utilise silicone-free polymers blended with thermal conductive materials. Both of them have exceptional conformability, achieving ultra-thin application thicknesses during use.

Thermally Conductive Potting Encapsulant and Thermally Grease: How to Apply

How to Apply Thermal Grease？

Thermal grease requires you to control the quantity applied based on the shape of the component surface and its contact area with the heat sink, and it cannot be prefabricated by suppliers in advance. Compared to thermal pads and thermal tape that can be directly affixed, its application is more complex. However, it is simpler to use than a thermally conductive potting encapsulant, which requires additional steps such as mixing and curing.

• Clean the Surface: Before applying thermal paste, you should clean the heat sink and component surfaces of old thermal interface materials, dust, water, and other contaminants to prevent them from influencing the filling effect and causing increased thermal resistance.
• Applying Thermal Paste: You may determine the appropriate quantity according to the supplier’s guidance, applying the thermal paste evenly or allowing it to spread naturally. Once applied, press the heat sink onto the thermal paste and remove any excess. For high-volume applications, you will need to procure additional automated dispensing equipment or screen printing equipment to achieve greater application efficiency and quality.

How to Apply Thermal Conductive Potting Encapsulant?

Thermal conductive potting encapsulants are employed to encapsulate components while simultaneously providing thermal conductivity and cooling effects. Their application procedures differ from those of thermal pads, thermal grease, and similar materials, typically being more complex.

• Cleaning: Thermal conductive potting encapsulants also require components to be kept clean and dry to ensure full contact with the encapsulant. You should clean them before use.
• Fixed Components: You must secure components firmly in place by SMT with a reflow process or some fixtures(like screws/clamps) before potting to prevent displacement during the potting process. If your components are not housed within a sealed enclosure, you should prepare a potting cavity of suitable dimensions and secure the components within it before assembly.
• Mixed Thermal Conductive Potting Encapsulant: Unlike thermal grease, thermal conductive potting encapsulant is typically a two-component formulation requiring mixing in the specified ratio according to the manufacturer’s instructions or supplier’s recommendations. For compatible dual-cartridge potting compounds, a static mixer nozzle can combine the two components during dispensing before the material enters the potting cavity. To prevent air ingress into the thermally conductive potting encapsulants—which can compromise thermal dissipation efficiency and mechanical strength—it is advisable to have a vacuum processing to eliminate air bubbles.
• Pouring: Slowly introduce the thermal conductive potting encapsulant into the housing or potting cavity, ensuring complete filling of the interior. For components with complex structures, using degassing equipment will yield superior potting results. Our potting materials exhibit good self-levelling and evaporation after keeping the potting in a static environment for 8-24 hours, varying against specific formulations.
• Curing: The application of thermal conductive potting encapsulant necessitates an additional curing process. Curing can be achieved at ambient temperature or through heating. The use of high-temperature curing has been significantly reduced many times in high-volume production. During curing, you’d better ensure the potted components remain protected from dust, moisture, vibration, and other disruptive factors.

Thermally Conductive Potting Encapsulant and Thermally Grease: Thermal Conductivity

Thermal Conductivity of Thermal Grease

Thermal grease typically has higher thermal conductivity than thermal potting encapsulants (1–8.5 W/m·K). Moreover, owing to its fluidity and extremely low bond line thickness, it minimises contact thermal resistance, delivering superior thermal transfer performance at equivalent thermal conductivity levels. Consequently, it is an appropriate choice for projects with heat dissipation requirements.

Thermal Conductivity of Thermally Conductive Potting Encapsulant

Thermally conductive potting encapsulants primarily serve a protective encapsulation function with additional thermal conductivity. Consequently, their thermal conductivity is typically lower (0.6–4 W/m·K). They are better suited for components with modest heat dissipation requirements but demanding high-strength protection and reinforcement.

Thermally Conductive Potting Encapsulant and Thermally Grease: Maintenance Requirements and Service Life

Maintenance Requirements and Service Life of Thermal Grease

The application and removal of thermal grease are more complex procedures. Over long periods of use, it may cause issues such as oozing, drying out, and attracting dust. Consequently, thermal grease has a relatively short lifespan of approximately 12 months. Beyond this period, its performance deteriorates significantly. Therefore, regular maintenance is required to sustain optimal functionality. This will also require you to undertake more maintenance work on it.

Maintenance Requirements and Service Life of Thermally Conductive Potting Encapsulant

Unlike thermal grease, thermally conductive potting encapsulants permanently bond and cure to components once applied and set. Whilst removal is possible through physical and chemical means (cutting, dissolving, etc.), such operations may damage your components.  Consequently, its application is more complex, yet it eliminates the need for replacement or maintenance. Furthermore, thermally conductive potting encapsulants maintain their effectiveness for approximately 10 to 20 years without degradation. This enables their use in equipment where maintenance is difficult or impossible, delivering exceptional stability.

Thermally Conductive Potting Encapsulant and Thermally Grease: Reusability

Can Thermally Grease be Reused?

Regarding thermal grease, whilst it does not require curing during installation, it will undergo compression. Moreover, thermal grease itself has a relatively short service life. After prolonged use, it dries out and exhibits separation between the thermal filler and base material, leading to a decline in performance. Consequently, thermal grease must not be reused.

Can Thermally Conductive Potting Encapsulant be Reused?

Thermally conductive potting encapsulants cannot be reused. On the one hand, once mixed, these compounds begin to solidify, altering their properties and rendering them unusable for reuse. On the other hand, once applied, thermal potting cannot be removed for reuse. Furthermore, thermal conductive potting encapsulants possess an exceptionally long service life. Therefore, prior to application, it is advisable for you to rigorously verify the intended application scenario and execute the operational procedures meticulously. This approach minimises material wastage and component damage, thereby avoiding additional cost expenditures.

Thermally Conductive Potting Encapsulant and Thermally Grease: Adhesiveness

Adhesiveness of Thermal Grease

Thermal grease is a relatively viscous paste-like material possessing a certain degree of stickiness to achieve better adhesion to component and heat sink surfaces. This also prevents the grease from leaking or dripping during equipment operation and movement. However, this stickiness is insufficient for securing components, and you can remove it quite easily. Consequently, thermal grease is not highly adhesive, making mechanical fasteners such as screws and clamps essential during installation.

Adhesiveness of Thermally Conductive Potting Encapsulant

Thermally conductive potting encapsulants have no tackiness before mixing and curing. Once mixed, they gradually become increasingly viscous. They ultimately achieve a high viscosity, particularly epoxy potting compounds, enabling a permanent bond with components(over 10 years). This permits you to use them in applications susceptible to vibration and impact without the need for additional fastening methods such as screws.

Thermally Conductive Potting Encapsulant and Thermally Grease: Cost

The Thermal Paste Cost

Compared to thermally conductive potting encapsulants, thermal grease incurs higher initial costs. Although only minimal quantities are required per component, their shorter lifespan necessitates frequent replacement. Furthermore, to enhance processing efficiency and achieve consistent quality during high-volume production, additional expenditure is incurred on automated dispensing equipment or screen printing apparatus. Overall, thermal pastes bring you a higher cost.

Thermal Conductive Potting Compound Cost

Although the initial cost of thermally conductive potting encapsulants is lower, installing individual components requires a greater quantity to fill the entire assembly. This may result in higher initial costs than thermal pastes. Furthermore, once cured, it cannot be removed or reworked, leading to extremely high failure costs. However, it offers a longer lifespan and requires no replacement. While room-temperature curing incurs no additional expense, it results in extended lead times. High-temperature curing, meanwhile, requires you to invest more money. Consequently, the overall cost of thermally conductive potting encapsulants remains high.

Thermally Conductive Potting Encapsulant and Thermally Grease: Application

Application of Thermal Grease

If your product demands superior thermal management, thermal grease is an ideal solution. Not only does it have outstanding thermal conductivity, but it also achieves satisfactory adhesion on rough component surfaces, enabling extremely low bond line thicknesses. Thermal grease may be applied between CPUs, GPUs, VRMs, RAM, and heat sinks in electronic devices; within automotive battery management systems and intelligent driving systems; as well as in industrial equipment and domestic appliances.

Application of Thermally Conductive Potting Encapsulant

Thermally conductive potting encapsulants are primarily used in heating elements requiring encapsulation protection. Their insulating properties, along with dustproof, moisture-resistant, shock-absorbing and corrosion-resistant capabilities, provide excellent safeguarding for heating components while offering more efficient heat dissipation. These compounds are suitable for applications demanding enhanced protection without frequent maintenance or replacement, such as outdoor transformers, inverters and automotive battery systems.

Thermally Conductive Potting Encapsulant and Thermally Grease

FAQs

Can Thermally Conductive Potting Encapsulant Replace Thermal Grease?

Thermally conductive potting encapsulants cannot replace thermal grease. On the one hand, thermal grease is used to fill the gap between components and heat sinks, whereas thermally conductive potting encapsulates requires complete encapsulation of components. Their methods of application differ. On the other hand, thermal grease offers higher thermal efficiency, while thermal potting compound possesses lower thermal conductivity.

Can Thermal Grease be Used with Silicon-Sensitive Components?

We offer silicone-free thermal grease for your selection. These do not produce silicone oil or vapour during use, making them safer for silicon-sensitive components.

Does Thermal Grease Offer Protection for Components?

Thermal grease has a degree of resilience, capable of cushioning components against vibration and impact. However, this protective function is not as effective as that provided by thermally conductive potting encapsulants.

How to Extend the Service Life of Thermal Paste？

Firstly, you must select a thermal grease for your application that offers suitable thermal conductivity and complies with relevant standards. Secondly, correct application is crucial to prevent excessive thickness or insufficient coverage. Furthermore, you should operate within the thermal grease’s optimal temperature range and avoid using it in extreme conditions.

Thermally Grease and Thermally Conductive Potting Encapsulant: Which is More Complex to Use?

The application of thermal grease is more complex than that of thermal pads, yet simpler than thermal potting compounds. Thermally conductive potting encapsulants require not only mixing and filling but also a curing process.

Are Thermally Grease and Thermally Conductive Potting Encapsulant Conductive?

Thermal paste and thermally conductive potting encapsulants are typically insulating, allowing them to be safely used in electronic equipment without affecting the circuitry.

Final Thoughts

After reading this, you should now understand the characteristics and applications of thermal grease and thermally conductive potting encapsulants. This information will enable you to make a more informed choice. Should you be seeking a reliable supplier, GALLOP INNOTEK possesses over a decade of experience in manufacturing thermal interface materials. We invite you to contact us for personalised service.