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Thermally Conductive Compounds Do More Than Transfer Heat

May 7, 2014

May 7, 2014 - When engineers select thermally conductive potting compounds, they usually ask how much heat the potting compound can transfer. But it’s equally important to ask how the potting compound transfers heat.

The answer boils down to the effect of thermally conductive fillers. There are dozens of different conductive fillers in use today, and each one interacts differently with the potting compound’s base resin to create a unique profile of mechanical and physical properties.

For example, consider two epoxy compounds that share a base resin and have the same thermal conductivity values. If these compounds rely on different conductive fillers, they can still exhibit substantial differences in viscosity, hardness, chemical resistance, flame resistance, shrink and other key properties. The same goes for compounds based on urethane or silicone.

With these differences in mind, here are a few examples of thermally conductive potting or encapsulation compounds that show the broad scope of property profiles:

  • 50–3150 FR Epoxy combines a thermal conductivity of 2.16 W/m·K with a UL 94 V–0 flame rating. It also offers low shrinkage and outstanding electrical insulation properties.
  • 50–2369 FR Urethane has a thermal conductivity of 1.15 W/m·K. Intended for surface mount applications, it offers a low-stress, low-exotherm cure to protect sensitive components.
  • 50–3185 NC Epoxy has a thermal conductivity of 1.36 W/m·K and also meets NASA’s low outgassing requirements.  Other properties include low thermal expansion and excellent electrical insulation
  • 50–1952 Silicone is a two-component potting and encapsulating compound with a thermal conductivity of 0.87 W/m·K. With a simple 1:1 mix ratio, it can be cured in thick sections.

Given the huge number of possible base resin and filler combinations, you should always ask your adhesives formulator for help in picking a compound that strikes the best balance between thermal conductivity and the other properties you require.

It also pays to try different potting or encapsulating compounds before committing to one. We’ve made it easy to try out different thermally conductive compounds with our free sample program.  If you fill out our online sample request form, our application engineers will evaluate your application and get you the right samples in just three business days.
 

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