Potting & Encapsulation Versus Impregnating
Resins
In the electrical and electronics industries, the most
commonly used insulating resins are epoxies, polyesters and polyurethanes.
In general, polyesters provide high thermal stability, epoxies offer
excellent chemical resistance and polyurethanes can be formulated
to provide flexibility at very low temperatures.
The impregnating resins are formulated as single component
(pre-catalyzed) or two-component (resin & catalyst). These resins
are cured with heat and depending on catalyst used, they can be cured
very fast or require a long cure cycle. Important parameters to consider
when formulating impregnating resins, regardless of the chemistry,
are--resin viscosity (for good penetration); cure rate (processing
time and resin retention); electrical, thermal and mechanical properties;
and storage stability especially for the pre-catalyzed products.
Potting and encapsulating resins are used to protect
sensitive components form harsh environments. Because of their sensitive
nature, chemical compatibility, exotherm during cure, and embedment
stress are some of the critical parameters to consider in formulating
these resin systems. Potting and encapsulating resins are typically
two-component (resin and curing agent), room temperature cure systems.
The cure rate can be from 30-60 minutes to 2-4 hours or longer.
For epoxy and polyester systems, in general, the faster
the cure, the higher the exotherm, shrinkage and embedment stress.
There are, however, newer systems available from Dolph which cure
fast without generating high exotherms. The polybutadiene systems
cure without any exotherm.
We can formulate products ranging from flexible (Shore
A:20-25) to rigid (Shore D:78-80) using one of the three classes of
products - epoxy, polyester and polybutadiene.
Our product line covers a broad spectrum of chemistry
and performance to meet the industry's needs. To discuss your present
and future applications contact your Dolph representative or our Customer
Service Department.
