Thermally Conductive Silicones - Techsil’s Terrific Trio

Techsil discusses the best thermally conductive materials in the market today, covering silicone adhesives, greases, potting compounds and gap fillers.

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

There are many types of conductive silicone materials available including pastes, cured pads, RTVs, gels, adhesives, gap fillers and greases. Which one engineers choose will be governed by the application and dispensing method preferred.

Techsil talks through the best new products in the market for each type:

Silicone Adhesives, RTVs, Pastes and Greases

These 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.

Consider Momentive TIA250RZ, a one-component, heat curable silicone adhesive with 2.2W/Mk thermal conductivity. It cures quickly with heat and adheres well to a variety of substrates without the use of a primer.

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.

Consider Momentive TIA216G, a 2-component, thermally conductive potting material which, with 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. It quickly cures to a soft rubber gel with exposure to heat and retains tacky adhesion on its cured surface. Non corrosive to metal, UL 94V-) approved and offers a thermal conductivity of 1.6 W/Mk.

Silicone Thermal Gap Filler Pastes

Used as a liquid dispensed alternative to prefabricated thermal pads gap fillers pastes offer an 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.

Consider Momentive TIA241GF, a 2-component, soft, non-slumping thermally conductive silicone paste used to dissipate heat from electronic devices. It offers physical stability that can allow improved processing; has a good thermal conductivity of 4.1W/Mk and is flame retardant.  

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