Silicones

Advantages

Inherently flame retardant.  High service temperature of 240°C/ 460°F. Tolerant of high humidity.  Stable electrical performance over wide temperature range (-50 °C/-60 °F) to (500 °C/930 °F). Good adhesion to metal. Retains strength at elevated temperatures >200 °C/390 °F better than Epoxy or DAIP.

Disadvantages

Expensive.  Low strength compared to Phenolic, Epoxy and DAIP at 20 °C (70 °F).

Applications

Encapsulation of electronic components. Glass laminates for high performance PCB.  Coatings for abrasion and weather resistance particularly for Polycarbonate.

Typical Properties

Property Value
Density (g/cm3)5 1.5
Surface Hardness RM80
Tensile Strength (MPa) 28
Flexural Modulus (GPa) 3.5
Notched Izod (kJ/m) 0.02
Linear Expansion (/°C x 10-5) 6
Elongation at Break (%) 2
Strain at Yield (%) N/A
Max. Operating Temp. (°C) 240
Water Absorption (%) 0.1
Oxygen Index (%) 40
Flammability UL94 V0
Volume Resistivity (log ohm.cm) 15
Dielectric Strength (MV/m) 15.8
Dissipation Factor1 kHz 0.002
Dielectric Constant 1 kHz 2.9
HDT @ 0.45 MPa (°C) 260+
HDT @ 1.80 MPa (°C) 300
Material Drying hrs @ °C NA
Melting Temp. Range (°C) 60 - 80
Mould Shrinkage (%) 2
Mould Temp. Range (°C) 180 - 200

Source : Abstracted from Plascams

For more information on Plascams please visit The Rubber and Plastics Research Association

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