What is the best thermal pad for different applications?

Thermal pads and glues are often used to attach heatsinks to components, especially in computers. Liquid metal thermal interfaces can be more conductive than thermal pads but they usually need a special high-end soldering gun for application. They also require more surface preparation, such as removing the oxide layer on aluminum using flux paste (hehe) or sandblasting. 

They also take longer to apply which makes it harder to replace the heatsink later on. Other types of thermal interfaces are phase change materials, graphite pastes, and ceramic/metal-filled pads, etc. Pads are cheaper, easier to use but less efficient.

Here are some common properties for different applications you should keep in mind:

Note: Thermal conductivity is given a thickness of 1mm, if you have a different thickness then the thermal conductivity will change but it’s unlikely to be drastic.

This table was compiled mostly from manufacturer specifications and may not be complete. Googling around for datasheets will usually give you more information about what type of pad to use.

Application Thermal Conductivity (W/m-K) at 1mm thickness

Heatsink attaching thermal pads

Aluminum oxide on aluminum surface: 0.2-0.3

  • Ceramic: 30-50
  • Copper: 400
  • Graphite: 6,000-8,000
  • Lead: 25
  • Silver: 420

Thermal adhesive (glue) is also available to attach heatsinks to components.

Aluminum oxide on aluminum surface: 0 –

  • Ceramic: 50-90
  • Copper: 400-1,100
  • Graphite/carbon paste: 6,000-8,000

Silver-filled silicone adhesive is used in most consumer electronics for attaching heatsinks to CPUs and GPUs. The thermal conductivity can vary depending on the manufacturer, size, and how it is applied.

Aluminum oxide on the aluminum surface: 0.2-0.3

  • Ceramic: 50-150
  • Copper: 400
  • Graphite/carbon paste: 6,000-8,000

Silver-filled silicone adhesive is used in most consumer electronics for attaching heatsinks to CPUs and GPUs.

Plastic: 0.5

Phase change materials (PCMs) are a type of thermal interface that changes phase from solid to liquid when heated, absorbing or releasing heat in the process. They can be used to control the temperature of electronic components. The most common type is paraffin wax which has a thermal conductivity of about 0.5 W/m-K.

Silicone: 2.5

Thermal pad is cheaper and easier to use but less efficient than most other thermal interfaces. If you’re looking for a cheap option and don’t need the best performance, thermal pads might be a good choice for you.

Aluminum oxide on aluminum surface: 0.2-0.3

  • Ceramic: 30-50
  • Copper: 400
  • Graphite/carbon paste: 6,000-8,000

Silver-filled silicone adhesive is used in most consumer electronics for attaching heatsinks to CPUs and GPUs.

  • Polyimide film (Kapton) : 1
  • Mylar: 2

Polyimide film is a type of thermal insulation with thermal conductivity of 1 W/m-K. It is often used to insulate the backside of a PCB from the component it is attached to, preventing the component from heating up the PCB.

Mylar is a type of thermal insulation with thermal conductivity of 2 W/m-K. It is often used to prevent components from heating up the PCB.

  • Ceramic: 30-50
  • Copper: 400
  • Graphite/carbon paste: 6,000-8,000

Silver-filled silicone adhesive is used in most consumer electronics for attaching heatsinks to CPUs and GPUs.

Aluminum oxide on aluminum surface: 0 – 0.2

  • Ceramic: 50-150
  • Copper: 400-1,100
  • Graphite/carbon paste: 6,000-8,000

Aluminum oxide is a type of thermal insulation with thermal conductivity of 0 W/m-K. It is often used to insulate the backside of a PCB from the component it is attached to, preventing the component from heating up the PCB.

Aluminum oxide on an aluminum surface: 0 –

  • Ceramic 50-90
  • Graphite/carbon paste 6,000-8,000

Silver-filled silicone adhesive is used in most consumer electronics for attaching heatsinks to CPUs and GPUs.

  • Paraffin wax: 0.5
  • Silicone: 2.5

Phase change materials (PCMs) are a type of thermal interface that changes phase from solid to liquid when heated, absorbing or releasing heat in the process. They can be used to control the temperature of electronic components. The most common type is paraffin wax which has a thermal conductivity of about 0.5 W/m-K.

Thermal pads are cheaper and easier to use but less efficient than most other thermal interfaces. If you’re looking for a cheap option and don’t need the best performance, thermal pads might be a good choice for you.

Conclusion:

Thermal pads are cheaper and easier to use but less efficient than most other thermal interfaces. If you’re looking for a cheap option and don’t need the best performance, thermal pads might be a good choice for you.

Leave a Comment