If you are selecting or replacing a new thermal interface material for your product to achieve better heat dissipation, you will find that both thermal paste and thermal pads offer excellent solutions, and it is confused to choose between them. However, their characteristics, performance, and applications differ. Selecting the correct thermal interface material can not only extend the product’s lifespan but also reduce additional costs. You can read this article before making an informed choice.
What is Thermal Paste?
Thermal paste(thermal grease) is a viscous, flowable paste-like thermal interface material. There are silicone-based thermal greases and non-silicone thermal greases for you to choose from according to different product requirements. It is typically manufactured from silicone-based compounds or silicone-free polymers with high thermal conductivity materials added. Its fluidity enables it to be pressed to extremely thin bond line thicknesses with minimal stress during application, achieving superior surface filling. This maximizes the thermal contact area, thereby delivering satisfactory heat dissipation performance.
What is the Thermal Pad?
Thermal pads, unlike thermal paste, have no fluidity, and they are solid sheets. Their manufacture involves adding curing agents alongside base materials and thermal fillers. Yet they remain very pliable, and their thickness and shape can be precisely pre-formed and cut to match your product, enabling easier installation between heating elements and enclosures (or heat sinks). A wide variety of thermal pads are available, differing in thermal conductivity, thickness, and material composition, suitable for the majority of applications.
The Difference Between Thermal Paste and Thermal Pads
Thermal Dissipation Performance of Thermal Pad and Thermal Paste
In terms of thermal conductivity, thermal pastes typically offer values between 1~8.5 W/m·K, whereas thermal pads provide a wider range (1~20 W/m·K). High-performance thermal pads available, with graphite thermal pads achieving thermal conductivities up to 1950 W/m·K for ultra-high-load heat dissipation. Although thermal paste generally has lower thermal conductivity than pads, it more effectively displaces air in gaps and achieves lower bond line thickness (BLT) than thermal pads. This minimizes contact thermal resistance, achieving better heat dissipation performance compared to thermal pads with equivalent thermal conductivity.
The Ease of Installation for Thermal Paste and Thermal Pads
Thanks to the supplier’s pre-moulding and precise cutting, thermal pads eliminate numerous steps in the application process, making installation remarkably straightforward. Simply peel off the protective surface layer and stick it onto the component surface. For high-volume production, it lends itself well to automation, achieving satisfactory efficiency. In contrast, thermal paste requires metering and application, making the installation process more complex than thermal pads. Furthermore, for mass production, additional automated dispensing equipment or screen printing apparatus would be necessary.
Maintenance and Service Life of Thermal Pads and Thermal Grease
The lifespan of thermal pads and thermal pastes varies by model and is influenced by the operating environment. The lifespan of thermal pads is approximately 2 to 10 years, allowing it to maintain stability during long use. Thermal paste, however, is more prone to drying out and leaking during use, resulting in degradation, and generally has a service life of approximately 12 months. Once aged, thermal paste becomes ineffective at dissipating heat and requires prompt replacement. Therefore, if you seek reduced maintenance and extended longevity for your products, thermal pads are the better choice.
Repeatability of Thermal Paste and Thermal Pads
Thermal paste becomes compressed and deformed after use, and is prone to drying out and oozing, so it cannot be reused. Thermal pads with adhesive layers are easily deformed and rendered ineffective when peeled off after use, and are not permitted for reuse. For thermal pads without adhesive layers, provided they show no signs of damage, deformation, or other issues, and their heat dissipation performance will still meet your requirements, they may be reused to minimize material wastage. However, if you want superior performance, you’d better not reuse them and use a new thermal pad.
Applications of Thermal Paste and Thermal Pads
Firstly, thermal pads support you get thicknesses ranging from 0.2mm to 20mm, permitting their use in larger component-to-heatsink gaps, whereas thermal paste is better suited for application in smaller gaps(<0.5mm). Secondly, whilst ultra-soft thermal pads exist for superior adhesion to irregular surfaces, thermal paste remains the first choice for highly textured or complex surfaces. Both materials deliver outstanding thermal performance, allowing you to use them in projects with high thermal loads. Additionally, silicone-free thermal pads and silicone-free thermal greases are available for components sensitive to silicone, preventing contamination and damage from silicone oils and vapours.
The Cost of Thermal Paste and Thermal Pads
Thermal pastes and thermal pads of different models vary in price, with higher thermal conductivity sheets commanding a premium. Generally speaking, thermal paste is less expensive than thermal pads. However, due to its shorter lifespan, it requires more frequent replacement, leading to higher operational costs. Furthermore, to enhance the mass production efficiency of thermal paste, you may need to purchase equipment that is more costly than that for thermal pads. Therefore, thermal pads offer greater cost-effectiveness over extended usage periods, while thermal paste remains a highly cost-effective choice.
When can Thermal Paste Replace Thermal Pads?
Rough Component and Heat Sink Surfaces
You are already know that thermal paste offers superior adhesion to uneven surfaces compared to thermal pads. Therefore, when selecting thermal interface materials for components and heat sinks with significant surface irregularities, thermal paste can serve as an excellent alternative to thermal pads. This also delivers enhanced thermal performance.
Smaller Component and Heat Sink Clearances
Should your component have surface height variations with substantial clearance between it and the heat sink (or enclosure), a thicker thermal pad proves more suitable. Substituting thermal paste not only complicates application but also introduces increased thermal resistance. Where minimal clearance exists between your component and heat sink, coupled with numerous minute irregularities, replacing the thermal pad with thermal paste is highly advisable. This approach maximizes thermal contact area while minimizing overall thickness.
Products Requiring Frequent Maintenance
Thermal paste is well-suited for products requiring frequent maintenance, as it also necessitates regular servicing to maintain performance. Given that thermal paste retains its efficacy for approximately 12 months, its use in hermetically sealed products where disassembly is not permitted can significantly shorten the product’s lifespan. Replacement may result in component damage and incur additional repair and replacement costs. Therefore, thermal paste may be employed as an alternative to thermal pads in products requiring frequent maintenance.
How to Select the Right Thermal Paste for Your Application
Choosing the Right Type of Thermal Paste
Silicone-based thermal pastes, low-volatility thermal pastes, and non-silicone thermal pastes are available. Silicone-based thermal pastes may generate silicone vapour or oil during use, potentially contaminating components. Non-silicone thermal pastes do not use silicone, but have lower thermal conductivity. Low-volatility thermal pastes, though also using silicone-based materials, produce less contamination and offer higher thermal conductivity than non-silicone variants. You may select the appropriate type according to your requirements to achieve more stable performance.
Select Thermal Paste with the Appropriate Thermal Conductivity
You may select thermal interface materials with thermal conductivities ranging from 1 to 8.5 W/m·K. Excessively low thermal conductivity may result in inadequate heat dissipation, hindering effective temperature control. While a very high thermal conductivity may increase costs. Should you be uncertain regarding the thermal conductivity required for your product, you may contact suppliers to arrange professional thermal simulation testing for precise measurements. Additionally, to select more specialised materials and achieve more stable performance, you may also consider thermal resistance and thermal impedance. Their values should likewise be restricted within a certain range.
Select Based on the Using Environment
Firstly, consider insulation and conductivity requirements. Most thermal pastes are insulating to safeguard circuits within equipment, preventing risks such as short circuits. Should you require it, conductive thermal pastes are available for more specialized applications. Secondly, different thermal pastes must be used within right temperature ranges to ensure extended service life. You’d better use them in temperatures of -50 to 200°C, with some high-temperature thermal greases capable of withstanding temperatures up to 220°C.
FAQs
What are the Applications of Thermal Pads and Thermal Paste?
You can use them in electronic devices (such as cameras, computers, and mobile phones), automobiles (battery systems, intelligent driving modules, etc.), industrial equipment (industrial robots, sensors, etc.), and household appliances.
Are There Alternative Thermal Interface Materials to Thermal Pad?
Sure, options include thermal paste, thermal gel, thermal tape, and thermal potting compound. Each has different advantages, allowing you to compare and select accordingly.
Is Thermal Paste Adhesive?
Thermal paste has adhesive properties to ensure better adhesion to components, casings, and heat sink surfaces. However, this adhesive strength is not robust and cannot provide a secure fixation. Should you require higher adhesive strength, thermal adhesives, thermal gels, or thermal potting compounds may be more suitable.
Can Thermal Pads and Thermal Paste be Used Together?
You must not use both thermal paste and thermal pads on a single component, as this will result in high thermal resistance and consequently reduce heat dissipation performance. However, you may use different types and grades of thermal paste or heat pads for various heating elements.
Can Thermal Pads Reduce Vibration?
Thermal pads possess flexibility, making them to effectively resist impact and vibration when used in automotive components. This reduces the stress experienced by the components, thereby enhancing the product’s safety. They can also absorb a degree of noise, resulting in lower noise levels.
Thermal Paste and Thermal Pads: Which is Better?
They are both excellent thermal interface materials, and the quality of the product depends on your requirements. For rough surfaces and small gaps, thermal paste is preferable. Thermal pads offer longer service life and require less maintenance, making them a good choice for smoother surfaces.
May I Cut the Thermal Pad?
You may trim the thermal pad to get the appropriate shape and size for your application, but you must not alter its thickness. Should the thickness prove unsuitable, you will need to purchase a new thermal pad of the correct thickness.
Final Thoughts
You can determine whether your product requires thermal grease instead of thermal pads. A prudent choice not only improves product reliability but also minimises cost losses. As an experienced TIMs supplier, GALLOP INNOTEK provides high-quality thermal grease, thermal pads, and other thermal interface materials. We also offer personalized guidance – please feel free to contact us.
