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The Advantages of Carbon-Based Thermal Gap Fillers

March 28, 2023
Most gap fillers today use non-electrically conductive fillers. Carbon-filled gap fillers, however, are electrically conductive.

Thermal gap fillers are used to fill air gaps between components in an electronic assembly or electronic system to enhance thermal behavior. These materials are ideal for filling gap openings that result from design restraints that don’t allow for direct contact between the heat source and the cold surface.

Thermal gap fillers are different from thermal greases, which are designed to break down contact resistance, rather than fill gaps. Traditional gap fillers often use ceramic fillers, such as aluminum oxide or boron nitrite, to achieve a desired thermal conductivity. These fillers are typically selected because of their high conductivity and proven performance.

The conductivity of a thermal gap filler depends on how much contact these fillers make with each other to create a thermal network inside the gap-filler pad. Achieving 100% contact is impossible—therefore the goal of a gap-filler manufacturer is to maximize the points of contact to achieve optimal thermal performance. This is accomplished by using fillers of different shape size and types.

Increasing the volume percentage of filler is often the easiest way to increase conductivity but it is often at the expense of compressibility. Finding the right conductivity is not that difficult, but finding a gap filler that will compress without creating too much stress is not. Compressibility is just as important as conductivity. The solution is finding polymer and filler material that can improve the conductivity while still maintaining a low compression. It can be a delicate balance—excess compression can break solder joints, damage modules, and diminish the performance of the product.

What You'll Learn:

  • Carbon Fillers
  • A New Carbon-Fiber Gap Filler
  • Addressing Oil Bleed
  • Maintaining a Clean Production Environment
  • Applications for CF210A

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