Gels

Gels are a special class of encapsulants that cure to an extremely soft material. Gels cure in place to form cushioning, self-healing, resilient materials. Cured gels retain much of the stress relief and self-healing qualities of a liquid while providing the dimensional stability of an elastomer. Typically, gels are used to isolate circuits from the harmful effects of moisture and other contaminants and provide electrical insulation for high voltages. However, their primary advantage is to provide the ultimate in stress relief in a cured material in order to protect the circuit and interconnections from thermal and mechanical stresses. Gels are usually applied in thick layers to totally encapsulate higher architectures and in particular high standing wirebonds – often in depths exceeding 80 mils (2 mm).

Another key characteristic of most gels is a naturally tacky surface after cure. This natural adhesion allows gels to gain physical adhesion to most common surfaces without the need for primers. This tacky nature also results in the unique ability to re-heal if the cured gel has been torn or cut. The ability to re-heal also permits the use of test probes directly through the gel for circuit testing.

Dow Corning ® brand dielectric gels are supplied as solventless and typically as low viscosity liquids. Most are designed as two part products with 1:1 mix ratios (parts A and B). Others are formulated as one part products, eliminating the need for mixing. The two part products generally allow for either room temperature or heat accelerated cure. One part products require heat cure. A few specialized one part gels allow for very rapid UV cure.

Elastomeric Encapsulants , which cure to a soft rubber, also are supplied in a wide range of product offerings and are covered in another section.

Dow Corning also supplies a line of Pre-Cured Gel Pads and Parts, which are covered in a separate section.