Comprehensive database of PCB laminates with electrical properties for impedance calculation.
Best for general purpose, <1 Gbps signals. Most cost-effective.
Suitable for 1-10 Gbps. Good balance of cost and performance.
Required for 10-28 Gbps. Data center and 5G applications.
Essential for 56G+ PAM4. Highest performance, highest cost.
| Material | Category | Dk | Df | Tg (°C) | Max Freq | Cost | HF |
|---|---|---|---|---|---|---|---|
FR-4 Standard Various | Standard | 4.35 | 0.02 | 135 | 1 GHz | $ | |
FR-4 High Tg Various | Standard | 4.3 | 0.018 | 170 | 2 GHz | $ | |
Isola 370HR Isola | Mid-Loss | 4.04 | 0.021 | 180 | 3 GHz | $$ | |
Isola FR408HR Isola | Mid-Loss | 3.68 | 0.0095 | 180 | 10 GHz | $$ | |
Panasonic Megtron 6 Panasonic | Low-Loss | 3.4 | 0.002 | 185 | 28 GHz | $$$ | |
Panasonic Megtron 7 Panasonic | Ultra Low-Loss | 3.3 | 0.0015 | 200 | 56 GHz | $$$$ | |
Rogers RO4350B Rogers | RF/Microwave | 3.48 | 0.0037 | 280 | 10 GHz | $$$ | |
Rogers RO4003C Rogers | RF/Microwave | 3.55 | 0.0027 | 280 | 18 GHz | $$$ | |
Taconic TLY-5 Taconic | RF/Microwave | 2.2 | 0.0009 | 0 | 40 GHz | $$$$ | |
Nelco N4000-13 EP SI Nelco | Low-Loss | 3.7 | 0.008 | 200 | 15 GHz | $$$ | |
EMC EM-890K EMC | Low-Loss | 3.45 | 0.003 | 200 | 20 GHz | $$$ | |
Shengyi S1000-2M Shengyi | Standard | 4.4 | 0.019 | 150 | 1 GHz | $ |
Dk affects signal propagation delay and impedance. Lower Dk means faster signal propagation and typically easier impedance control with wider traces.
Df (loss tangent) determines signal attenuation at high frequencies. Lower Df is critical for high-speed designs where signal integrity matters.
| Data Rate | Recommended Material | Max Df Target | Typical Applications |
|---|---|---|---|
| < 1 Gbps | Standard FR-4 | 0.020 | GPIO, I2C, SPI, UART |
| 1 - 5 Gbps | Mid-Loss (370HR, IS400) | 0.015 | USB 3.0, SATA, PCIe Gen2 |
| 5 - 10 Gbps | Mid/Low-Loss (FR408HR) | 0.010 | 10GbE, PCIe Gen3 |
| 10 - 28 Gbps | Low-Loss (Megtron 6) | 0.005 | 25GbE, PCIe Gen4, DDR5 |
| 28 - 56 Gbps | Ultra Low-Loss (Megtron 7) | 0.002 | 56G PAM4, PCIe Gen5 |
| > 56 Gbps | Ultra Low-Loss / RF | < 0.002 | 112G SerDes, mmWave |
Temperature at which the resin transitions from rigid to soft. Choose based on assembly process.
Temperature at which chemical decomposition begins (5% weight loss). Critical for rework.
Material cost increases significantly with lower loss. Design appropriately for your application.
Higher Dk results in lower impedance for the same geometry. When switching to a lower-Dk material, you'll need narrower traces to maintain the same impedance. Use our calculator to compare.
Dk values in datasheets are typically measured at 1 MHz or 1 GHz. At higher frequencies, Dk generally decreases slightly. Always verify the measurement frequency and consider using frequency-dependent values for accurate high-speed design.
FR-4 and similar materials have woven glass fiber reinforcement. The Dk of glass (~6.2) differs from resin (~3.2), causing localized Dk variations. This can cause skew in differential pairs. Spread glass or filled resin variants mitigate this effect.
Rogers and PTFE-based materials are typically used for RF/microwave applications above 10 GHz, antennas, and when extremely low and stable Dk is required. They offer superior electrical performance but require specialized processing and are significantly more expensive.
Don't over-specify materials. Standard FR-4 works well for most designs. Only use expensive low-loss materials for high-speed lanes that actually need them.
Use low-loss materials only where needed (top/bottom layers with high-speed routing) and standard materials for inner layers to optimize cost.
Not all fabricators stock all materials. Check availability early to avoid delays. Some specialty materials have long lead times.
Request the fabricator's specific Dk/Df values for their material and construction. Datasheet values are typical; actual values may differ.