Dielectric gels are a specialist type of encapsulant with the unique capacity to remain as a soft and flexible material post-curing. Available as one or two part materials, this product group meets the needs of most applications and process situations, and can be considered for use on actuators.
As a solvent-less material, dielectric gels are typically low-viscosity liquids. Although available as one or two-part gels, two-part products are the most commonly designed and are distributed with a 1:1 mix ratio in the form of parts A and B, allowing for either a room temperature or a heat accelerated cure. Those that are formulated as one-parts create ease and convenience for the user, as the need for mixing is eliminated. However, they do require a heat cure. Advancements have found that a few specialised one-part gels now allow for a very rapid UV cure.
One of the most impressive characteristics of dielectric gels is the product’s ability to re-heal, if it becomes broken or cut. “As such, dielectric gels are an incredibly resilient material and provide cushioning, while also offering the dimensional stability of an elastomer,” states Tom Harrison, technical sales manager, Dow Corning, a leading manufacturer of these gels. “The reason behind dielectric gels ability to re-heal is their natural tacky surface, which forms post-cure. This surface will adhere to most common substrates without the assistance of a primer.”
STRESS RELIEF
Key features of dielectric gels include: temperature resistance, low modulus – good dampening properties, low viscosity, tacky adhesion at room temperature and high dielectric strength (>18kV/mm). This is guaranteed to create reliability, as well as several key typical benefits, including: under the hood usage, thermal and mechanical stress protection and an easy flow around components, which will prevent formation of thermally induced voids.
“Dielectric gels have excellent stress relief properties, similar to those of a liquid,” adds Harrison. “For this reason, this specialist material is commonly used on electronic circuits to isolate the circuit from the harmful effects of contaminants. Dielectric gels not only provide electrical insulation for high voltages, they also provide the electronic circuit stress relief and protection from thermal and mechanical stresses.”
There are many applications where the choice of a dielectric gel are said to be advantageous. This could be in the form of a material application from conventional insulators to applications where dielectric properties are controlled for active device architectures. In addition, these can include: sensor potting, ECU potting, power module potting, rectifiers, semiconductors, transducers, capacitors, transformers and for the use with cable joints. “Dielectric gels are a truly resilient material type that can cater to a great number of complex applications,” states Harrison.