Typical Formulation Ingredients
Ingredient
Parts by weight
Epoxy resin (Epon 826, Momentive)
Alumina (T-60, Aluminum Company of America)
Part B: Converter Portion
Hexahydrophthalic anhydride (Allied Chemical Corp.)
Diethyamino ethanol (S-2 Accelerator, Penwalt Corp.)
Asbestine (3X, International Talc Co. Inc.)
(Source: Momentive Specialty Chemicals)
Typical Properties
Filler content by weight, %
Hardness at 25°C, Shore D
Tensile strength at 23°C, psi
Coefficient of linear thermal expansion, in/in/°C
Volume resistivity, 1 min @ 500 volts, at 23°C, ohm-cm
Dielectric constant at 60 Hz and 23°C
Dissipation factors at 60 Hz and 23°C
Resulting Properties
The formulation above shows a rigid epoxy resin formulation that can be used as either an adhesive or a potting compound. The formulation is often used in the electrical / electronic industry where a low coefficient of linear thermal expansion is required because of the substrate materials also having a low coefficient of expansion.
Hexahydrophthalic anhydride is commonly used to achieve low viscosity which can result in high filler loadings. It also has excellent electrical properties and outdoor weather resistance. The type of filler and high filler content contribute to the low coefficient of linear thermal expansion.