Techsil’s top 4 optically clear potting compounds for electronics 05 September 2019

Electronic and LED applications are increasing in variety and complexity which creates new challenges for protective potting compounds. Engineers must ensure that sensitive electronic components can perform in all environments whether it be indoor, underfoot, in the air, at sea, in space or underwater.

Many components benefit from being encapsulated such as sensors, capacitors, resistors and transformers to protect them from mechanical shocks, moisture, chemicals and other environmental factors. Product selection is dependent on a number of factors in addition to colour, such as:

  • Viscosity – can it flow into the housing and around components.
  • Hardness and density when cured – to give maximum protection.
  • Operating temperatures of cured resin.
  • Thermal conductivity.
  • Flame retardancy.

The specifications for encapsulants for potting electronics, LEDs and electrical products are high, with many design engineers looking for products offering brilliant long-term clarity, good protection from environmental factors, along with excellent thermal characteristics.

As adhesive specialists, Techsil has selected a range of four of the best optically clear potting compounds for electronics designed to have, in particular, an excellent refractive index and great UV stability; perfect for potting LED lighting assemblies for maximum light transmission; potting electronic assemblies where component identification is desirable and other products where high transparency and aesthetics are important.

Momentive RTV615 silicone
Momentive RTV615 is a crystal clear, low viscosity, two part silicone potting compound which cures at room temperature to a high strength rubber (44 shore A) with a thermal conductivity of 0.19 W/mK. It is a low viscosity, pourable liquid which remains flexible at low temperatures and up to 204 ⁰C and is used to protect components against shock, vibration and environmental hazards. Available in a variety of pack sizes.

Techsil® PU22985 polyurethane
Techsil® PU29985 is a two part water clear potting polyurethane which cures to form a tough 85 Shore A material with good abrasion and hydrolysis resistance and thermal conductivity of 0.3 W/mK. It offers a good green strength for situations where areas of stress concentration from components might disrupt curing. Developed for potting of luminaires, LEDs, uplights, arrays, tracks and doming applications. Supplied in easy to use twinpacks.

MG Chemicals® 832WC epoxy
MG 832WC is an extremely hard two part water clear potting epoxy that cures to Shore 82D and offers extreme environmental, mechanical and physical protection for PCBs and electronic assemblies. Non yellowing on exposure to UV and high temperatures, it provides excellent electrical insulation, extremely high compressive and tensile strength and a service temperature range of -40 to 140 ⁰C.

Techsil® RTV27905 silicone gel
Techsil® RTV27905 is a soft, adherent, clear two part silicone potting gel. RTV27905 is the softest gel from a wider family of similar silicone gels. It is used to provide protection from vibration and thermal or mechanical shock. Techsil RTV 27905 has excellent dielectric properties and also gives protection from water and many environmental contaminants. This product is flexible down to -55°C, and suitable for use up to +200 ⁰C. Available in several pack sizes.

Claire Aldridge Deputy Editor t: +44 (0) 1727 814 450

Having joined the magazine in 2012, Claire developed her knowledge of the industry through the numerous company visits, exhibitions and conferences she attended both in the UK and abroad.

Claire prides herself on keeping readers well informed and up to date with the latest industry news.