Thermal pads are a commonly used thermal interface material. Using it can provide efficient heat dissipation for your device, preventing it from degrading or even damaging due to overheating. This article details how thermal pads work, and knowing this can help you make a better choice.
What Are Thermal Pads
Thermal pads are soft, pre-moulded gaskets made of graphite, ceramic or silicone with thermally conductive fillers, used to fill the gap between the heating element and the heat sink. They typically have high thermal conductivity to enhance thermal efficiency. You can choose them for electronics, automotive control units, telecoms equipment, LED lighting and more.
How Thermal Pads Conduct Heat
Filling Gaps
Component surfaces are very difficult to achieve complete flatness under normal conditions. Thermal pads are usually soft and fill surface unevenness well. It has a double-sided adhesive layer to hold the heating element and heat sink in place. Not only does this make your product more reliable, but it also ensures complete contact and minimizes thermal resistance. The flexibility of thermal pads can also absorb and mitigate noise and strongly affect to a degree, reducing component damage and enhancing the reliability of your product.
Contact Resistance Reduction
If you fit the heating element directly to the heat sink, the surface unevenness will be filled with air. Air with very weak thermal conductivity reduces the efficiency of heat transfer, resulting in a radiator that does not function well. Thermally conductive pads are used to bridge irregular interstitial gaps well at low compression force requirements, replacing air to reduce thermal resistance.
Effective Heat Transfer
When you use your equipment, components running at high speeds generate a lot of heat that collects on the surface of the components. Excessive temperatures can affect the performance of the equipment and the life of the components in the long run. And the thermally conductive pads will quickly absorb this heat and spread it across the entire surface of the gasket. They also provide even heat distribution, effectively preventing localised overheating from harming your device. The heat is then transferred to the heat sink.
Factors Affecting Thermal Pads Work
Thermal Conductivity of Thermal Pads
Thermally conductive gaskets have different thermal conductivities for different models. Install enough thermal conductivity for your equipment to ensure stable operation. If the thermal conductivity is too low, high loads will shorten the service life of the thermally conductive gasket and will not provide good heat dissipation performance. Excessive thermal conductivity will result in excess performance and increased costs.
Material Selection
Common materials for thermally conductive gaskets include silicone, graphite flakes, phase change materials, ceramics and so on. Different materials have different properties, and you should choose the right thermal pads according to different use scenarios.
- Silicone thermal pads: Silicone thermal pads are usually made of materials with high thermal conductivity. It is highly flexible and can fit a variety of complex surfaces. However, its high temperature resistance is general. If you want to use thermal pads at high temperatures, you need to consider carefully.
- Graphite thermal pads: Graphite thermal pads have a very high thermal conductivity and are more resistant to high temperatures, but they are more costly.
- Phase Change Thermal Conductive Pads: Phase change materials transfer heat in solid-liquid transformations, enabling intelligent temperature regulation. You can use it in applications that require more precise temperatures.
- Ceramic thermal conductive pads: Ceramic thermal conductive pads are available in alumina ceramic sheets, aluminium nitride ceramic sheets and so on. They also have a high thermal conductivity and a long service life.
Thickness of Thermal Pads
The thinner the thermal pads, the lower their thermal resistance and the more efficiently they conduct heat. Therefore, you should make sure that the thermal shim is the thinnest possible while ensuring that the shim can completely cover the uneven surface. And you need to choose the right thickness based on the surface characteristics of the component. If the surface is smooth, you can choose a thinner one. But if the surface is very uneven, you must choose a thicker thermal pad.
Clean Surface
Dust, grease and other impurities will increase the thermal resistance and reduce the thermal conductivity of the thermal gasket. Therefore, before installation, you should thoroughly clean both surfaces to ensure they are stain-free. If you are replacing a thermally conductive gasket, you should completely remove the previous interfacing material and clean it with a specialised cleaner to ensure there is no residue.
Operating Temperature of Thermal Pads
Thermally conductive gaskets are usually used at temperatures from about -60 to 200°C. If you use them outside of this temperature range, the performance of the thermally conductive gasket may deteriorate, and if used for a long period of time, it may even be damaged.
Shelf Life of Thermal Pads
Thermally conductive gaskets have a shelf life of up to 24 months from the date of manufacture. Performance will deteriorate beyond the shelf life, so you should use it within the shelf life. And after use, store the remaining shims in their original packaging in a cool, dry environment.
Conclusion
If you are in the process of selecting the right thermal interface material for your project, consider the suitability of thermal pads. GALLOP INNOTEK has 10+ years of experience with profound knowledge of field applications and an insightful background of TlM products. If you need, feel free to contact us to become your partner!
FAQs
Are thermal pads electrically conductive?
Thermal pads are commonly used in electronics and most are designed to be electrically insulating. However, there are also thermal pads that are electrically conductive, such as graphite thermal pads and thermal pads with conductive metal fillers. If you are going to use them in circuits, choose electrically insulating thermal pads to keep circuits safe and equipment reliable.
Can I Reuse the Thermal Pads?
Thermally conductive pads provide long-lasting and consistent performance. If the thermal pads are intact and still have a good bond, you can reuse them. However, it is recommended that you use new thermal pads for optimal heat dissipation.
What applications can I use thermal pads for?
You can use the thermal pads in electronic products (mobile phones, tablets, computers, etc.), automotive electronic control modules, telecommunication equipment, LED lighting and so on. Provide them with good heat dissipation, prolong service life and improve work stability.
