Which silicone is suitable for electronics?

Name: Ameba AG
Address: Stieracker 20, Frick, AG, 5070, CH
Telephone: +41 61 322 42 24

Silicone potting compounds give electronic assemblies lasting protection against moisture, dust, vibration and temperature cycling. They stay elastic over a wide temperature range, insulate electrically and put very little mechanical stress on components – which is why they are the first choice in electronics when assemblies need long-term protection.

Selection criteria

Viscosity: low-viscosity compounds flow into narrow gaps and under components and de-aerate more easily.
Curing system: addition-curing silicones cure without by-products and with virtually no shrinkage – even in closed housings and thick layers. Condensation-curing silicones are less sensitive to contamination.
Hardness: soft compounds and gels relieve sensitive components and solder joints; harder compounds give better mechanical protection.
Transparency: clear compounds allow visual inspection, repair and potting of LEDs and displays.
Special requirements: fire protection (e.g. EN 45545-2 for rail vehicles, UL 94), heat dissipation or UV and weather resistance.

Suitable products

ELASTOSIL RT 601 A/B – clear standard potting compound (9:1) for PCBs, sensors and modules.
ELASTOSIL RT 604 A/B – crystal clear, very low viscosity, soft vulcanizate.
ELASTOSIL RT 607 A/B – higher hardness and very good heat stability.
ELASTOSIL RT 622 A/B – for fire-protection applications in rail vehicles to EN 45545-2.
ELASTOSIL RT 628 A/B – grey, UV and weather resistant for outdoor use.
ELASTOSIL RT 745 A/B – soft, adheres to many substrates without primer.
WACKER SILGEL 612 A/B – very soft, clear silicone gel for particularly sensitive electronics.
ELASTOSIL RT 675 A/B – thermally conductive potting compound for heat-generating components.

Practical tips

Dose the components exactly in the specified mixing ratio and mix thoroughly.
With addition-curing compounds, avoid contact with sulphur, amines, tin compounds and some plasticisers, as they can inhibit curing. If in doubt, run a preliminary test.
For adhesion to metal, glass and plastics use a suitable primer, e.g. Grundierung G790 TF.
For thick layers, de-aerate after mixing to avoid air bubbles.

Questions about choosing a product? Call us on +41 61 322 42 24 (Mon–Fri 08:15–12:00 and 13:30–17:00) or write to info@ameba.ch.