Thermally conductive silicones from the specialists – Techsil’s terrific trio

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 and so are asking more of the components and materials used inside. Thermally conductive silicones are a great choice for dissipating heat away from the electrical component and the surrounding equipment. Silicones are a very versatile material to consider in general; they bond to different combinations of substrates and offer performance reliability over a wide temperature range in challenging environments. When used for potting, the cured flexibility of silicone provides excellent protection by absorbing mechanical vibration and thermal shock.

As specialists in thermal management, Techsil offer many types of conductive silicone materials to help with many of the challenges faced by engineers today. These include pastes; cured pads; RTVs; gels; adhesives; gap fillers and greases. Techsil, in conjunction with their partners Momentive Performace Materials, are excited to be able to talk through the best new products to hit the market for each type.

 Silicone adhesives, RTVs, pastes and greases

Applied in a thin layer between the electronic component and its heatsink these materials will work to minimise thermal resistance. Pastes and greases are non-curing, allowing rework whereas RTVs and adhesives will bond the heat sink to the component while also offering an effective heat transfer medium.

SilCool™ TIA250RZ is 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.

SilCool TIA216G is 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 they 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.

SilCool™ TIA241GF is 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.

Other thermally conductive options

 Prefabricated silicone thermal gap filler pads, these 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.

Or you could consider silicone phase change materials which work as 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.

We understand every application and every surface is different, this is why at Techsil we like to get involved at the design stage to understand the substrates being used, the heat generated, how to eliminate the air and achieve the best possible BLT (bond line thickness) for our customers. For advice on any of Techsil’s thermally conductive materials or to find out more about the grades Techsil has to offer, contact our Technical Team directly via technical@techsil.co.uk or call 01789 773232.

www.techsil.co.uk

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