Relative Dielectric Constants

Er is the substrate or dielectric constant, relative to free space. Following are constants of some common materials:

Material

Dielectric Constant

Air

1.0

Alumina, 99.5%

10

G10/FR4 Epoxy glass

4.8 (varies)

PolyEthylene, DE-3401

2.26

Polyhexamethyleneadipamide (Nylon)

2.9

Polyolefin, irradiated

2.32

Polystyrene

2.53

Polystyrene, cross linked

2.53

Polystyrene, glassed cross linked

2.62

PolyTetraFluoroEthylene (PTFE)

2.10

Polyvinal formal (Formvar)

2.8

PTFE, glass microfiber

2.35

PTFE

2.10

PTFE, woven glass

2.55

PTFE, woven quartz

2.47

Pyrex glass

4.84

Quartz, fused

3.8

RT/Duroid

2.20

RT/Duroid, PTFE ceramic filled

10.5

Water, distilled

77

Note: Foamed materials have lower dielectric constants. These data are approximate; consult manufacturer for critical applications.

See Also:
Loss Tangent

Resistivity