RBC-4503 Resin

UL Listed: Yes
, Thermally Conductive, UL Listed
3 hours
Pot Life
Mixed Viscosity (cps)
Thermal Conductivity
(cal/sec/cm2/°C/cm X 10-4)
-65 to 130
Operating Temperature Range (°C)

RBC-4503 is a low viscosity, UL listed epoxy for 94 V-O flame retardency. It is designed for applications where thermal conductivity, excellent electrical insulation, high heat distortion and superior thermal shock properties are required. RBC-4503 can be cured at room temperature or elevated temperature to fit a variety of applications. It can be used as a heat sink for large castings or as an encapsulant for heat generating components.


Mixed Viscosity @ 25oC,cps: 3,300
Mixed Viscosity @ 60oC,cps: 700
Shelf Life, (closed Container @ 25oC): 12 Months


Color: Black
Specific Gravity @ 25oC: 1.48
Hardness, Shore D: 87
Linear Shrinkage, in./in.: 0.003
Moisture Absorption 24 hr. water boil, %: 3.8
Izod Impact Strength, ft. lbs./in. of notch: 0.28
Tensile Strength @ 25oC, psi: 8,100
Compressive Strength @ 25oC, psi: 19,100


Thermal Conductivity, cal/sec/cm2/oC/cm X 10-4: 27.3
Thermal Stability, 1000 Hrs. @ 175oC, % Wt. Loss: 0.35
Coefficient of Thermal Expansion, in./in./oC X 10-6: 27
Heat Distortion Temperature, oC: 53
Operating Temperature Range, oC: -65 to 130


Volume Resistivity @ 25oC, ohm-c: 5×1016
Dielectric Strength, volts/mil:  480
Dielectric Constant @ 25oC, 100 KC: 5.7
Dissipation Factor @ 25oC, 100 KC: 0.018
The above properties are typical of a system cured with Hardener A-122


AB-56: A fast, room temperature curing system with good chemical and thermal properties.
A-122: A resilient, low viscosity system with slightly longer pot life, that exhibits excellent resistance to thermal shock.


Weigh the desired amount of RBC-4503 into a clean container and combine with recommended hardener in the proper ratio as shown below.

Hardener Parts by Weight
per 100 pts. Resin
Pot Life 
100 grams @ 25oC
AB-56 20 15-30 minutes
A-122 13 3 hours

Recommended Cure Schedule:

Hardener Cure @ 25oC Cure @ 65oC Cure @ 100oC  Cure @ 130oC
AB-56 6 hours 10 minutes 
A-122 24 hours 3 hours 2 hours 1 hour