How to Select the Right Type of Thermally Conductive Silicone

Thermally Conductive Silicones

On this page:

  1. Comparison of Different Types of Thermally Conductive Silicones
  2. Techsil’s Top Three Thermally Conductive Silicones

Thermally conductive silicones are used in electronic devices to dissipate heat away from the component and the surrounding equipment. Modern devices are required to be smaller and more powerful and consequently generate more heat. It is imperative keep these devices cool in order to prolong the life of the equipment, reduce energy consumption and prevent damage to surrounding components.

There are many types of silicone materials available including pastes, cured pads, RTVs, gels, adhesives, gap fillers, phase change materials and greases. The choice will be governed by the application and dispensing method preferred.

 

Comparison of Thermally Conductive Silicones

Silicone Adhesives, RTVs, Pastes and Greases

Silicone thermal interface materials, including adhesives, pastes, and RTVs, are applied in a thin layer of material between the electronic component and its heatsink in order to minimise its thermal resistance. Pastes and greases are non-curing, allowing rework. RTVs and adhesives are used to bond the heat sink to the component while also offering an effective heat transfer medium.

Silicone Thermal Gap Filler Pastes

Used as a liquid dispensed alternative to prefabricated thermal pads. They offer improved thermal dissipation thanks to excellent wet-out compared to rigid pads. As these fillers can be dispensed by automated systems there are used by sectors demanding higher production throughput, thinner bond lines, and reduced mechanical pressure on components and solder joints. As a further advantage any design changes that alter the position or types of components used can be accommodated quickly by changing the shape and volume of thermal material deposited. If automatic dispensing equipment is used, it can be reprogrammed, avoiding any need to reorder gap-filler pads in different sizes or shapes.

Silicone Potting Compounds

Some heat generating circuits benefit from potting or encapsulation in a heatsink enclosure using a thermally conductive silicone potting compound. This has the benefit of providing both heat dissipation and environmental protection all in one.

Prefabricated Silicone Thermal Gap Filler Pads

Silicone thermal gap filler pads can be cut to size and applied by hand. They have a higher thermal resistance when compared with thermal pastes due to the thickness of the gap pad versus the very low thickness achievable with a thermal paste.

Silicone Phase Change Materials

Phase change silicone materials are an effective alternative to thermal greases. The materials change from a solid at specific phase change temperatures and flow to provide a total wet-out of the interface without overflow. The result is a thermal interface comparable to grease.

Techsil’s Top Three Thermally Conductive Silicones

Here are Techsil’s Top Three Thermally Conductive Silicones including a

  • Potting Compound
  • Adhesive
  • Gap Filler Paste

Momentive TIA216G Thermally Conductive Silicone Potting Compound

TIA216G is a 2-component, thermally conductive potting material. Its low viscosity allows the material to conform to intricate shapes of thermal interfaces and contributes to the reduction of contact interference in complex designs. TIM27616 quickly cures to a soft rubber gel with exposure to heat and retains tacky adhesion on its cured surface.

  • Key Features
  • Good thermal conductivity – 1.6 W/mK
  • Low viscosity
  • Fast cure with exposure to heat
  • Room temperature cure possible
  • Easy to use 1:1 mix ratio by weight and volume
  • Repairable
  • Noncorrosive to metal
  • UL 94V-0
  • Temperature range from -40°C to 200°C

Momentive TIA250RZ Thermally Conductive Silicone Adhesive

TIA250RZ is a one-component, heat curable silicone adhesive. This product cures quickly with heat and adheres well to a variety of substrates without the use of a primer. It is used as an adhesive between electronic components and heat sinks

Key Features

  • Good thermal conductivity – 2.2 W/mK
  • Ready to use: one component
  • Low temperature, fast cure
  • Primerless adhesion to many types of substrates

Momentive TIA241GF Liquid-Dispensed Silicone Thermal Pad / Gap Filler

TIA241GF gap filler is a 2-component, soft, thermally conductive silicone material used to dissipate heat from electronic devices. Its non-slumping pasty consistency offers physical stability that can allow improved processing. It can be used as a liquid dispensed alternative to prefabricated thermal pads in a broad array of thermal designs for electronic applications.

Key Features

  • Good thermal conductivity – 4.1 W/mK
  • Fast, low temperature cure
  • Convenient 1:1 mix ratio by weight
  • Retained softness after cure for enhanced stress relief during thermal cycling
  • Excellent slump resistance (stays in place)
  • Repairable
  • Flame retardant: UL94V-0 equivalent
  • Glass bead options available (180 & 250μm) for bond line thickness control

For advice on any of our thermally conductive materials or to request a sample please contact technical@techsil.co.uk

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