Stycast 5952-1

Stycast 5952-1 is a thermally conductive, two-component, silicone encapsulant specifically formulated for the protection of heat-generating electronic devices. It combines high thermal conductivity with excellent electrical insulation, making it a premier choice for potting transformers, rectifiers, thyristors, and power supplies. Its non-corrosive nature and ability to cure rapidly in thick sections allow it to be used as a reliable casting material, as well as in the production of thermal pads and heat sinks.

In its uncured state, the system consists of a red resin (Part A) and a white hardener (Part B) that are mixed at a simple 1:1 ratio. The mixed material has a viscosity of 30,000 mPa·s and a density of 2.05 g/cm³, providing a pourable consistency that fills complex cavities effectively. It offers a 100-minute pot life at 100°C, though power mixing and vacuum evacuation are highly recommended to ensure a homogeneous, void-free mixture. Because this is an addition-cure silicone, care must be taken to avoid contact with contaminants like sulphur, nitrogen-containing materials, or heavy metal salts, which can inhibit the cure.
The primary cure is achieved in 1 hour at 100°C, though it will be handleable after 24 hours at room temperature. For applications demanding the highest thermal stability, a post-cure of 2 hours at 175°C is advised to reach optimum properties. Once fully cured, Stycast 5952-1 exhibits a Shore A hardness of 75 and a thermal conductivity of 0.8 W/(m-K). It maintains its integrity under mechanical stress with an elongation of 45% and a tensile strength of 580 psi.

Electrically, the cured material is a high-grade insulator with a volume resistivity of 1×10¹⁴ ohm-cm and a dielectric strength of 17 kV/mm. It maintains a low dielectric constant of 5.0 at 1 MHz, ensuring minimal signal interference in power-sensitive components. While the silicone provides moderate tear strength and good elongation, the use of Primer S 11NC is suggested when bonding to non-silicone substrates to maximise adhesion and safeguard against potential surface inhibition.