# Dielectric Constant, Strength, & Loss Tangent

QDielectricLoss =

Loss Tangent =

Dielectric Loss =

Values presented here are relative dielectric constants (relative permittivities). As indicated by er = 1.00000 for a vacuum, all values are relative to a vacuum.

Multiply by ε0 = 8.8542 x 10-12 F/m (permittivity of free space) to obtain absolute permittivity. Dielectric constant is a measure of the charge retention capacity of a medium.

In general, low dielectric constants (i.e., Polypropylene) result in a "fast" substrate while large dielectric constants (i.e., Alumina) result in a "slow" substrate.

The dielectric loss tangent is defined by the angle between the capacitor's impedance vector and the negative reactive axis, as illustrated in the diagram to the right. It determines the lossiness of the medium. Similar to dielectric constant, low loss tangents result in a "fast" substrate while large loss tangents result in a "slow" substrate.

Beware that the exact values can vary greatly depending on the particular manufacturer's process, so you should seek out data from the manufacturer for critical applications.

The dielectric constant can be calculated using:   ε = Cs / Cv , where Cs is the capacitance with the specimen as the dielectric, and Cv is the capacitance with a vacuum as the dielectric.

The dissipation factor can be calculated using:   D = tan δ = cot θ = 1 / (2π f RpCp) ,  where δ is the loss angle, θ is the phase angle, f is the frequency, Rp is the equivalent parallel resistance, and Cp is the equivalent parallel capacitance.

Note: All values can vary by very large amounts depending on the specific material. Check with the MatWeb.com website for more details. Other resources: Electrical Properties of Insulators, Dielectric Properties of Materials.

 Substance Dielectric Constant(relative to vacuum) DielectricStrength(V/mil) LossTangent Max Temp(°F) ABS (plastic), Molded 2.0 - 3.5 400 - 1350 0.00500 - 0.0190 171 - 228 Air (STP, @900 kHz) 1.00058986 30 - 70 Alumina - 96%                - 99.5% 10.09.6 0.0002 @ 1 GHz0.0002 @ 100 MHz0.0003 @ 10 GHz Aluminum Silicate 5.3 - 5.5 Bakelite 3.7 Bakelite (mica filled) 4.7 325 - 375 Balsa Wood 1.37 @ 1 MHz1.22 @ 3 GHz 0.012 @ 1 MHz0.100 @ 3 GHz Beeswax (yellow) 2.53 @ 1 MHz2.39 @ 3 GHz 0.0092 @ 1 MHz0.0075 @ 3 GHz Beryllium oxide 6.7 0.006 @ 10 GHz Butyl Rubber 2.35 @ 1 MHz2.35 @ 3 GHz 0.001 @ 1 MHz0.0009 @ 3 GHz Carbon Tetrachloride 2.17 @ 1 MHz2.17 @ 3 GHz <0.0004 @ 1 MHz0.0004 @ 3 GHz Diamond 5.5 - 10 Delrin (acetyl resin) 3.7 500 180 Douglas Fir 1.9 @ 1 MHz 0.023 @ 1 MHz Douglas Fir Plywood 1.93 @ 1 MHz1.82 @ 3 GHz 0.026 @ 1 MHz0.027 @ 3 GHz Enamel 5.1 450 Epoxy glass PCB 5.2 700 Ethyl Alcohol (absolute) 24.5 @ 1 MHz6.5 @ 3 GHz 0.09 @ 1 MHz0.25 @ 3 GHz Ethylene Glycol 41 @ 1 MHz12 @ 3 GHz -0.03 @ 1 MHz1 @ 3 GHz Formica XX 4.00 FR-4 (G-10) - low resin                  - high resin 4.94.2 0.008 @ 100 MHz0.008 @ 3 GHz Fused quartz 3.8 0.0002 @ 100 MHz0.00006 @ 3 GHz Fused silica (glass) 3.8 Substance Dielectric Constant(relative to vacuum) DielectricStrength(V/mil) LossTangent Max Temp(°F) Gallium Arsenide (GaAs) 13.1 0.0016 @ 10 GHz Germanium 16 Glass (Corning 7059) 5.75 0.0036 @ 10 GHz Glass (lead silicate) 7 - 14 (Table 2: LS30-LS32) Glass, Crushed / Powdered (Corning 7070) 4.6 0.000600 924 Gutta-percha 2.6 Halowax oil 4.8 High Density Polyethylene (HDPE), Molded 1.0 - 5.0 475 - 3810 0.0000400 - 0.00100 158 - 248 Ice (pure distilled water) 4.15 @ 1 MHz3.2 @ 3 GHz 0.12 @ 1 MHz0.0009 @ 3 GHz Kapton® Type 100            Type 150 3.92.9 74004400 500 Kel-F 2.6 Lexan® 2.96 400 275 Lucite 2.8 Mahogany 2.25 @ 1 MHz1.88 @ 3 GHz 0.025 @ 1 MHz0.025 @ 3 GHz Mica          Mica, Ruby 4.5 - 8.05.4 3800 -5600 Micarta 254 3.4 - 5.4 Mylar® 3.2 7000 250 Neoprene 6 - 9 600 Neoprene rubber 6.26 @ 1 MHz4 @ 3 GHz 0.038 @ 1 MHz0.034 @ 3 GHz Nomex® 800 450 Nylon 3.2 - 5 400 280 Oil (mineral, squibb) 2.7 200 Paper (bond) 3.0 200 Paraffin 2-3 PEEK™ 450G Polymer (@23 °C, 100 MHz) 3.2 ~900 0.003 Phenolica (glass-filled) 5 - 7 Phenolics (cellulose-filled) 4 - 15 0.03 @ 100 MHz Phenolics (mica-filled) 4.7 - 7.5 Plexiglass® 2.2 - 3.4 450 - 990 Polyethylene LDPE/HDPE 2.26 @ 1 MHz2.26 @ 3 GHz 450 - 1200 0.0002 @ 100 MHz0.00031 @ 3 GHz 170 Polyamide 2.5 - 2.6 Polycarbonate, Molded 2.8 - 3.4 380 - 965 0.000660 - 0.0100 239 - 275 Polypropylene 2.2 500 250 Polystyrene 2.5 - 2.6 500 0.0001 @ 100 MHz0.00033 @ 3 GHz Polyvinylchloride (PVC) 3 725 140 Porcelain 5.1 - 5.9 40 -280 Pyrex glass (Corning 7740) 5.1 335 Substance Dielectric Constant(relative to vacuum) DielectricStrength(V/mil) LossTangent Max Temp(°F) Quartz (fused) 4.2 150 - 200 RT/Duroid 5880(go to Rogers) 2.20 Rubber 3.0 - 4.0 150 - 500 170 Ruby 11.3 Silicon 11.7 - 12.9 100 - 700 0.005 @ 1 GHz0.015 @ 10 GHz 300 Silicone oil 2.5 Silicone RTV 3.6 550 Soil (dry sandy) 2.59 @ 1 MHz2.55 @ 3 GHz 0.017 @ 1 MHz0.0062 @ 3 GHz Soil (dry loamy) 2.53 @ 1 MHz2.44 @ 3 GHz 0.018 @ 1 MHz0.0011 @ 3 GHz Steatite 5.3-6.5 Strontium titanate 233 Teflon® (PTFE) 2.0 - 2.1 1000 0.00028 @ 3 GHz 480 Tefzel® (1 kHz - 3 Ghz) 2.6 - 2.3 0.0007 - 0.0119 300 Tenite 2.9 - 4.5 Transformer oil 4.5 Vacuum (free space) 1.00000 Valox® 1560 400 Vaseline 2.16 0.00004 @ 0.1 GHz0.00066 @ 3 GHz Vinyl 2.8 - 4.5 Water (32°F)         (68°F)          (212°F) 88.080.455.3 80 0.04 @ 1 MHz0.157 @ 3 GHz Water (distilled) 76.7 - 78.2 0.005 @ 100 MHz0.157 @ 3 GHz Wood 1.2 - 2.1 0.04 @ 0.1 GHz0.03 @ 3 GHz

Supplemental information provided by website visitor James S. for complex dielectric:

The dielectric constants at the top of [this] page are reminiscent of the propagation constants given by Roald K. Wangsness, Electromagnetic Fields, 2nd Ed., John Wiley & Sons, New York, 1986, p. 383, Eq. (24-42) and (24-43). The sixth equation given on the web page is correct. That equation, as given by P. Hoekstra and A. Delaney in Dielectric properties of soils at UHF and microwave frequencies, J. Geophys. Res., v. 79, 10 Apr 1974, p. 1699, "... is written as

K*(ω) = K'(ω) - iK"(ω) , where

K'(ω) is the dielectric constant and

K"(ω) is the dielectric loss factor.

Hence,

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Note: Thanks to Gareth for correcting the omission of a square root sign in the dielectric equations.

Thanks to Craig B. for correcting the loss tangent for Teflon (0.00028 rather than 0.0028).