Epoxy Resin Chemistry

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Epoxy resins are widely used in the electronics industry because of their superior electrical and mechanical qualities, as well as their ability to withstand chemicals and high temperatures. Their use protects electrical components from dust, moisture, and short circuits, and because typical epoxy resins have a higher thermal conductivity than air, they dissipate heat from components more efficiently, extending service life.

Today, a large variety of epoxy-based resin systems are accessible, each with its own set of characteristics. Epoxy resins have a slow cure time, however employing amines, amine modified polymers, or polyamides as hardeners, a variety of cure speeds and cured characteristics can be achieved. While the reaction might be extremely quick, it can also be extremely exothermic, posing the risk of a runaway reaction.

This can be addressed by changing the hardener’s chemistry or employing fillers that absorb heat from the reaction and can also act as a flame retardant. It’s worth noting that the temperature at which a resin is cured affects not only the speed with which it cures, but also the quality of the cured resin. As a result, it’s a good idea to run several tests before committing to a given cure rate.

Many resins, particularly epoxies, have changed market requirements as a result of the increased use of electric vehicles. The numerous performance parameters required for vehicle components are constantly expanding and improving, as e-mobility is a rapidly changing and evolving market. Electrolube is at the forefront of offering solutions to suit the requirements of the automotive electronics industry because resins are used in many spots on a vehicle, from sensors and displays to the motors themselves.

It’s nearly a given that each new design generation of components will shrink in size while increasing in power. In general, more power means more heat is emitted, which is why there is a push to create new resins with better higher temperature operating ranges, which is important for both continuous and short-term operating temperatures. Increased thermal conductivity of resins is also required, allowing for better heat dissipation from electrical components.

Electrolube’s epoxy resin portfolio comprises a selection of transparent, white, and black single- and two-part formulations with a variety of beneficial attributes for potting, sealing, and dipping, such as superior electrical and thermal characteristics, flame retardancy, and chemical and fuel resistance.

The Chemistry of Polyurethane Resins

Epoxy resins cure to form a hard, rigid encapsulation, whereas polyurethane resins cure to form an elastomeric or rubbery encapsulation, which is especially beneficial if the circuit to be potted contains fragile components. Polyurethane resins, like epoxy resins, offer chemical, dust, and moisture resistance, as well as excellent electrical insulation and adherence to most metal and plastic substrates. Polyurethanes, unlike their epoxy equivalents, have a lower exotherm during cure, even in the quicker curing systems.

. It is crucial to note, however, that cured polyurethane resins should not be exposed to temperatures above 130°C in continuous use.

In comparison to epoxies, polyurethane resins are widely employed in a variety of applications, where their inherent flexibility decreases the amount of stress given to components. This allows for the easy potting of components with thin or weak legs.

A variety of polyurethane resins are also thixotropic, which means that their viscosity is low during mixing but rapidly increases once poured, allowing for precise resin placement and preventing the resin from flowing through any small holes on the PCB.

LEDs have been the default lighting choice for the majority of applications due to an exponential increase in their use over the last few years. LEDs, on the other hand, require some kind of protection, depending on the environment in which they are used. Polyurethane resins that are optically clear have become a popular solution for protecting LEDs in harsh situations.

These resins have been specifically designed with a completely aliphatic polymer backbone to provide the best UV yellowing resistance. Designers are increasingly considering the use of resins not just to give a level of protection for lighting units, but also to improve aesthetics. The LEDs might appear as individual light sources or as a solid bar of light, depending on the resin used.

As previously stated, most polyurethane resins have a maximum operating temperature of 130°C; however, with careful formulation, this maximum temperature limit can be increased to 150°C while maintaining the same flexibility and chemical resistance as a polyurethane.

Electrolube’s polyurethane resins are available in white, black, blue, clear straw, hazy/cloudy, and optically clear formulations, and offer a variety of properties to meet the needs of high-temperature environments as well as those exposed to chemical contamination, mechanical stress or shock, and moisture ingress, just like the epoxy range.

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