Optical Silicon vs. PFA

Optical silicon and PFA belong to fundamentally different material chemistries. Optical silicon is a ceramic material, while PFA is polymeric. Therefore, their performance will be even more dissimilar than would be suggested by the difference in properties. There are 12 material properties with values for both materials. Properties with values for just one material (20, in this case) are not shown.

For each property being compared, the top bar is optical silicon and the bottom bar is PFA.

Optical Silicon (Si)Perfluoroalkoxy (PFA)

Metric UnitsUS Customary Units

Mechanical Properties

Tensile Strength: Ultimate (UTS), MPa		110
Tensile Strength: Ultimate (UTS), MPa		30

Thermal Properties

Maximum Temperature: Mechanical, °C		1350
Maximum Temperature: Mechanical, °C		260

Melting Onset (Solidus), °C		1560
Melting Onset (Solidus), °C		300

Specific Heat Capacity, J/kg-K		700
Specific Heat Capacity, J/kg-K		1000

Thermal Conductivity, W/m-K		150
Thermal Conductivity, W/m-K		0.25

Thermal Expansion, µm/m-K		3.0
Thermal Expansion, µm/m-K		120

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz		12
Dielectric Constant (Relative Permittivity) At 1 MHz		2.6

Otherwise Unclassified Properties

Density, g/cm³		2.3
Density, g/cm³		2.2

Refractive Index		3.5
Refractive Index		1.4

Common Calculations

Strength to Weight: Axial, points		13
Strength to Weight: Axial, points		3.9

Strength to Weight: Bending, points		22
Strength to Weight: Bending, points		10

Thermal Diffusivity, mm²/s		93
Thermal Diffusivity, mm²/s		0.12