Thermal paste vs. thermal pads

Thermal paste vs. thermal pads

Thermal paste vs. thermal pad

differences from Thermal pads compared to Thermal Compound

Thermal interface materials are undoubtedly a very critical aspect in the design of electronic components. They can very well tell the difference between a working product and a faulty product.

The purpose of thermal pads and thermal grease is to create a preferential heat transfer path between heat-producing components such as integrated circuits (CPUs) and heat spreaders such as a heatsink.

The surface of a CPU or heatsink is never going to be completely flat or even. There will be tiny bumps, gaps, and gaps that allow air to pass through the components.

Since air is not a good conductor of heat, these gaps have a very negative effect on heat transfer.

Therefore, a thermal interface material with high thermal conductivity is needed to fill these gaps and improve thermal conductivity between CPU and heatsink. In our post 8 ready-made thermal management solutions we have described various materials that can be used for heat dissipation. We supply thermal pads with thermal conductivities up to 15 W/mK and thermal compounds with thermal conductivities up to 10 W/mK.

Thermal Compound

Thermal paste or cooling paste is a sticky mass that is applied between the heatsink and the CPU as the most common thermally conductive material. High quality pastes perform best when it comes to dissipating and transferring heat.

Thermal paste sticks for a very long time and is a very good option when it comes to dissipating heat to the heat sink: A layer of thermal paste ensures that the component surface is completely wetted.

Since thermal paste is a viscous liquid, it fills all micro-indentations on the component or on the underside of the heatsink. This achieves a much better heat dissipation to the heat sink.

Unfortunately, the application is often not easy, especially for beginners, and can lead to difficulties. Also, unlike some types of thermal pads, thermal paste is not designed to bridge large gaps.

Thermal pads

Thermal pads are a lot easier to install than thermal paste. The pads are already included with some heat sinks, as they can be attached cleanly and easily and even newcomers have no problems here. Thermally conductive pads are also preferred in industry. Unfortunately, the heat conduction is not always quite as good as that of the thermal paste. However, very small gaps will still remain between the processor and the thermal pad. These small air gaps result in slightly lower thermal conductivity, as air is less thermally conductive.

It is important to remember that thermal pads are a one-time solution. They must be replaced entirely if the heatsink is to be relocated or replaced. In this case, all residues of glue must also be removed, otherwise new bumps and gaps will appear. But thermal paste must also be completely removed and replaced.

Thermal pads vs. thermal paste: durability

From a durability perspective, some designs are expected to last for decades in harsh environments. Using thermal paste to dissipate heat for the heatsink outperforms any pad and is the more robust option in terms of wear resistance. In contrast, a thermal pad becomes brittle over time under repeated thermal cycling, which can disrupt the thermal conduction path between the heatsink and the component

This is simply due to the material used in these products. Thermal paste or thermal grease sticks and solidifies after application. Thermal pads, on the other hand, consist of a spongy material or soft, rubber-like material. Thermal paste is more durable and less expensive. This applies in particular to recurring temperature cycles.

Advantages of thermal pads over thermal paste

  1. No pollution – Applying thermal paste can be a messy process. Using thermal pads is a simple peel and stick application.
  2. Fills larger gaps – Thermal pads are available up to 20mm as opposed to a thin layer of thermal paste.
  3. Easier installation - Thermal pads can be stamped to the exact specifications of the component to ensure a perfect fit - every time.
  4. conformity – Thermal pads conform precisely regardless of the surface to ensure no air leaks through. However, small air pockets may remain.

Common mistakes and how to avoid them

Installing thermal grease and thermal pads is a common problem. So here are some tips to avoid them:

Never use paste and pads together. Just because the two are used together doesn't mean better heat conduction is achieved. The opposite is even the case. Applying thermal paste to the pads reduces the desired effect.

Also should never multiple pads on top of each other to be attached. Placing two or more pads on top of each other between the heat sink and the CPU can damage the processor as heat builds up.

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