Silicones and Electronics
Long-term, reliable protection of sensitive circuits and components is becoming more important in many of today’s delicate and demanding electronic applications. Silicones 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. In addition to sustaining their physical and electrical properties over a broad range of operating conditions, silicones are resistant to ozone and ultraviolet degradation, have good chemical stability and are available in a variety of useful forms as conformal coatings, encapsulants and adhesives. Dow’s broad range of general purpose and specialty products offers you a choice of materials for your application needs.

Dow silicone encapsulants are supplied as two-part liquid component kits comprised of:
Mix Ratio Components (by weight or volume) (as supplied)
1:1 Part A/Part B
10:1 Base/Curing agent
When liquid components are thoroughly mixed, the mixture cures to a flexible elastomer, which is suited for the protection of electrical/electronic applications.

Dow silicone encapsulants cure without exotherm at a constant rate regardless of sectional thickness or degree of confinement.

Dow silicone elastomers require no post cure and can be placed in service immediately following the completion of the cure schedule with an operating temperature range of -45 to 200 °C (-49 to 392 °F). Select materials have been classified by Underwriters Laboratories and/or meet military specifications.

Standard silicone encapsulants require a surface treatment with a primer in addition to good cleaning for adhesion while primerless silicone encapsulants require only good cleaning.

Gels are a special class of encapsulants that cure to an extremely soft material. They are used to provide high levels of stress relief to sensitive circuitry. Gels perform many important functions in electronics. Their major job is to protect electronic assemblies and components from adverse environments by:

• Functioning as dielectric insulation
• Protecting the circuit from moisture and other contaminants
• Relieving mechanical and thermal stress on components

Dow offers a line of standard gels, a line of low-temperature gels for applications requiring low-temperature performance. A line of toughened gels for use where chemical adhesion and dimensional stability are required, and a line of specialty gels for applications requiring low extractables, ultra-violet (UV) cure, or resistance to solvents and fuels. In addition, Dow offers custom gels that can be quickly tailored to meet specific application needs for properties such as color, viscosity, hardness, and cure rate.

Ensuring that electronics products function as they are designed to is just one piece of the materials solution Henkel delivers. Protecting printed circuit boards and electronic assemblies from thermal cycling and adverse environmental conditions is the other critical component for product durability and reliability. Under the leading Hysol® and Stycast™ brands, Henkel offers several PCB protection products to minimize external product stress and maximize performance. Our portfolio of conformal coatings keeps moisture, humidity and other adverse conditions from deteriorating printed circuit boards used in harsh marine, automotive, aerospace and consumer electronics applications. Henkel also strives to keep environmental consciousness at the forefront of all our product development efforts, which is why we have moved toward solvent-free, low-VOC materials and processes.

Henkel’s potting and encapsulation compounds protect PCBs and electrical devices by enhancing mechanical strength, offering electrical insulation, and protecting against vibration and shock.

Selecting the best catalyst
A catalyst determines many of the final properties of a STYCAST system. It's selection is as important as that of the resin as it has a significant influence on final cured hardness, mixed viscosity, temperature capabilities and physical properties.

Understanding viscosity
Viscosity is the measure of the internal resistance of friction when a material moves against itself. It is typically measured using a rotating spindle instrument (viscometer). The amount of force required to turn the spindle (torque) at a selected speed (rpm) is measured. A simple calculation converts this internal resistance to viscosity. Thicker materials equates to higher torque values, hence, higher viscosities.