Material Properties
| Property | RT/Duroid 5880 | RO4003C (comparison) |
|---|
| Relative permittivity εr | 2.20 ± 0.02 | 3.55 ± 0.05 |
| Loss tangent tan δ (10 GHz) | 0.0009 | 0.0027 |
| Loss tangent tan δ (77 GHz) | 0.0013 | 0.004 |
| Phase velocity vp | 0.73c | 0.60c |
| Temperature coeff εr | −125 ppm/°C | +40 ppm/°C |
| Material type | PTFE/glass microfiber | Woven glass/hydrocarbon |
| PCB process | Special handling required | Standard FR4 process |
50 Ω Microstrip on RT/Duroid 5880
| H (mm) | W for 50 Ω | εe | λ/4 at 28 GHz | λ/4 at 77 GHz |
|---|
| 0.127 (5 mil) | 0.38 mm | 1.88 | 2.44 mm | 0.89 mm |
| 0.254 (10 mil) | 0.76 mm | 1.89 | 2.44 mm | 0.88 mm |
| 0.508 (20 mil) | 1.52 mm | 1.90 | 2.43 mm | 0.88 mm |
Insertion Loss Advantage at mmWave
| Frequency | RT/Duroid 5880 | RO4003C |
|---|
| 10 GHz (100 mm) | ~0.8 dB | ~1.5 dB |
| 28 GHz (100 mm) | ~2.0 dB | ~4.5 dB |
| 60 GHz (100 mm) | ~4.5 dB | ~12 dB |
| 77 GHz (100 mm) | ~5.5 dB | ~16 dB |
PCB Design Notes for Duroid 5880
- PTFE is soft — requires careful via drilling and controlled-depth routing
- Low εr means wider 50 Ω traces (W/H ≈ 3) — easier fine-pitch pad alignment
- Negative temperature coefficient: as temperature rises, f₀ of resonators shifts up
- Not suitable for high-density digital PCB (soft, low Tg) — use in RF layers of multilayer board
RF View Microstrip Calculator: Enter εr=2.20 for RT/Duroid 5880 to compute 50 Ω trace width, εe, guided wavelength, and quarter-wave lengths at mmWave frequencies. Offline in the Utilities tab.
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