New dielectric gel formulations available

Edited by the Engineeringtalk editorial team Aug 29, 2001

RW Greeff Silicones and Lubricants now has an extended range of Dow Corning dielectric gels for protection of sensitive circuits and components in harsh environments

RW Greeff Silicones and Lubricants, the UK's major distributor of Dow Corning industrial silicone products and high performance industrial chemicals, now has an extended range of Dow Corning dielectric gels for protection of sensitive circuits and components in harsh environments.

The new dielectric silicone gels provide long term, reliable protection of sensitive circuits and components increasingly found in many delicate and demanding electronic applications.

The silicone gels function as durable dielectric insulation, as barriers against environmental contaminants and as stress relieving shock and vibration absorbers over a wide temperature and humidity range.

Two new gels are available, each offering fast room temperature curing, 1:1 mix ratio, low viscosity and primerless adhesion.

Dow Corning 3-4207 type is a two part toughened gel with UL 94 V-1 flammability classification.

Dow Corning 3-4150 type is an extremely soft gel offering two part rapid room temperature/heat curing.

Typical applications include encapsulating, protecting and preserving both macro and microelectronic devices that require dielectric insulation, moisture resistance, vibration damping or high/low temperature resistance.

Both gels offer excellent room temperature adhesion, good dielectric properties and are designed for use with automatic dispensing equipment.

Operating temperature range is from -45 to +150 C.

Typical characteristics of the Dow Corning 3-4207 Dielectric Tough Gel when cured are durometer hardness of 62 Shore 00, tensile strength of 45psi and tear strength of 9.2ppi.

Typical electrical characteristics of this gel, which is translucent green when cured, include dielectric strength of 16.5kV/mm, dielectric constant of 2.85 at 100Hz and 2.86 at 100kHz and volume resistivity of 7.1 x 1013 ohm-cm.

Dow Corning 3-4150 type is a transparent green gel featuring a room temperature cure time of 45/90mins (time to initial non-flow/time to 90% of final value, 80g sample) and accelerated heat cure time of 5.4mins at 135 C.

Electrical characteristics include dielectric strength of 15.1kV/mm, dielectric constant of 2.85 at 100Hz and 100kHz and volume resistivity of 7 x 1015 ohm-cm.

Besides sustaining their physical and electrical properties over a broad range of operating conditions, the new silicone gels are resistant to ozone and UV degradation and offer good chemical stability.

The gels are very soft and cure in place at room temperature to form a cushioning, self-healing resilient gelled material.

Cured gels retain much of the stress relief and self-healing qualities of a liquid while developing the dimensional stability of an elastomer.

A further benefit of the new dielectric gels is the ability to gain access to the protected circuitry in order to make repairs.

Removal of the gel is possible using Dow Corning Ozone Safe (SO) brand fluids.

In addition, if only one circuit component needs to be replaced, a soldering iron can be applied directly through the gel to remove the component.

After work has been completed, the repaired area can be cleaned with a brush or forced air and the opening can be re-filled with additional gel product.

RW Greeff Silicones and Lubricants is one of the UK's leading distributors of high performance industrial chemicals with more than 30 years experience serving the UK industry.

The company is the major distributor for Dow Corning engineering silicones and Molykote speciality lubricants and offers a complementary range of top quality products from other world leading manufacturers.

ISO 9002 accredited, RW Greeff offers a fast, efficient delivery service to all areas of the UK.