Panasonic's industry-leading low-loss laminates for high-speed digital design. From 25G Ethernet to 112G PAM4 SerDes, Megtron enables the world's fastest data links.
0.002 (M6) to 0.0015 (M7) vs 0.020 FR-4
Tight tolerance for consistent impedance
Minimizes glass weave skew for diff pairs
Standard fabrication, no special chemistry
Mid-Loss
Low-Loss
Ultra Low-Loss
Extreme Low-Loss
Insertion loss is the critical limiting factor for high-speed channels. Lower Df directly translates to better signal integrity at the receiver. Here's how materials compare at 25 GHz:
| Material | Df | Loss @ 10" | Loss @ 20" | Max Data Rate |
|---|---|---|---|---|
| FR-4 Standard | 0.020 | ~12 dB | ~24 dB | 3 Gbps |
| Mid-Loss (370HR) | 0.010 | ~6 dB | ~12 dB | 10 Gbps |
| Megtron 6 | 0.002 | ~2.5 dB | ~5 dB | 28 Gbps |
| Megtron 7 | 0.0015 | ~2 dB | ~4 dB | 56 Gbps |
* Loss values are approximate at 25 GHz Nyquist for 50 Gbps NRZ. Actual loss depends on trace geometry, copper roughness, and frequency. PAM4 signals are more sensitive to loss than NRZ.
400G/800G Ethernet switches with 56G PAM4 SerDes requiring sub-3dB channel loss.
GPU/TPU interconnects with 112G SerDes for massive data movement between chips.
Long-reach 20"+ channels for blade servers and telecom equipment.
High-frequency test fixtures and probe cards requiring ultra-low loss.
Pair Megtron with HVLP or VLP copper (Rz < 1μm) to minimize skin effect losses. Standard RTF copper negates much of Megtron's advantage above 10 GHz.
Use Megtron for high-speed signal layers only. Power planes and low-speed layers can use high-Tg FR-4 to reduce cost by 30-40%.
For 56G+ PAM4, request spread glass or flat glass prepreg to minimize intra-pair skew from fiber weave effect. Critical for <5ps skew budgets.
Via stubs create resonances that hurt high-frequency performance. Back-drill all high-speed vias to leave <10 mil stub length.
Use IBIS-AMI models and channel simulation (Keysight, Cadence) to verify eye opening before committing to expensive Megtron builds.
For production, specify insertion loss and return loss measurements on test coupons to verify material and fabrication quality.
The general rule: use Megtron 6 when your data rate exceeds 10 Gbps and trace lengths exceed 6 inches. At 25 Gbps NRZ or 56G PAM4, FR-4 losses become unacceptable (>6dB/in at Nyquist). Megtron's lower Df (0.002 vs 0.020) reduces insertion loss by ~80%, keeping eye diagrams open.
Megtron 7 has lower Df (0.0015 vs 0.002), lower Dk (3.3 vs 3.4), and better glass weave construction. M7 is designed for 56G PAM4 and beyond, while M6 handles 25G NRZ comfortably. M7 costs about 30-50% more than M6 and requires tighter manufacturing controls.
Yes, hybrid stackups are standard practice for cost optimization. Use Megtron for high-speed signal layers (typically outer layers and one or two inner layers for critical SerDes) and FR-4 for power/ground planes and low-speed signals. Match Tg values (use High-Tg FR-4) and work with an experienced fab.
Megtron's lower Dk (3.3-3.4 vs 4.0-4.2 for FR-4) means you need narrower traces to achieve the same impedance. For 50Ω on Megtron 6, expect trace widths about 15-20% narrower than FR-4 with the same dielectric height. Use manufacturer-provided Dk values at your operating frequency.
Most advanced PCB fabricators support Megtron. In North America: TTM, Sanmina, Multek. In Asia: Unimicron, AT&S, WUS. For Megtron 7, check with your fab specifically as it requires precise processing. Lead times are longer than FR-4, typically 3-4 weeks for prototypes.