When you’re routing 25 Gbps SerDes lanes across a 24-layer backplane or trying to close a 400G link budget on a dense switch fabric board, the laminate choice stops being a procurement decision and becomes an engineering one. The Nanya NPG-198 ultra low loss PCB material has been showing up more frequently in these conversations, and for good reason. It sits in a performance tier that was previously dominated by expensive Japanese and American materials, but with fabrication characteristics that make it practical for volume production.
This article covers everything a working PCB engineer needs to evaluate NPG-198 — the actual specs, what they mean in real designs, how it compares to alternatives, and where it fits in the current landscape of high-speed networking hardware.
What Is the Nanya NPG-198 and Where Does It Fit?
Nanya New Material Technology has been expanding its high-performance laminate portfolio aggressively over the past several years. The NPG-198 is positioned at the top of that portfolio — a halogen-free, ultra-low-loss, high-Tg laminate built specifically for applications where standard low-loss materials like FR408HR or even mid-tier options start showing their limits.
The “198” designation reflects the material’s target Tg range, and the NPG prefix indicates the non-halogen, high-performance series. What makes NPG-198 distinct from other materials in the Nanya PCB lineup is the combination of an aggressively optimized resin system with tight Dk/Df control across a wide frequency range.
The target market is clear: 10G, 25G, 40G, 100G, and 400G networking hardware, 5G infrastructure, high-performance computing interconnects, and any application where insertion loss budgets are tight and signal frequencies push into the 10–40 GHz range.
Why Ultra-Low-Loss Matters at 10G and Above
At 1 Gbps, almost any decent FR-4 variant gets the job done. At 10 Gbps, you start caring about Df. At 25 Gbps and above, Df becomes one of the primary design constraints.
The physics is straightforward. Dielectric loss in a PCB trace scales linearly with frequency and linearly with Df. Double the frequency, double the dielectric loss contribution. At 25 GHz, a material with Df of 0.020 (standard FR-4) produces roughly 4–5x more dielectric loss than a material with Df of 0.004–0.005 (NPG-198 class). That’s not a marginal difference — it’s the difference between a functional link and a failed one on any trace longer than a few inches.
Nanya NPG-198 Ultra Low Loss PCB: Full Electrical Specifications
The electrical properties are the primary reason engineers specify NPG-198. Here’s the complete picture:
| Property | Value | Test Frequency | Test Method |
| Dielectric Constant (Dk) | 3.3 – 3.5 | 10 GHz | IPC-TM-650 2.5.5.5 |
| Loss Tangent (Df) | 0.003 – 0.005 | 10 GHz | IPC-TM-650 2.5.5.5 |
| Dielectric Constant (Dk) | 3.5 – 3.7 | 1 GHz | IPC-TM-650 2.5.5.5 |
| Loss Tangent (Df) | 0.005 – 0.007 | 1 GHz | IPC-TM-650 2.5.5.5 |
| Dielectric Constant (Dk) | ~3.4 | 28 GHz | — |
| Loss Tangent (Df) | ~0.004 | 28 GHz | — |
| Volume Resistivity | >10^8 MΩ·cm | — | IPC-TM-650 2.5.17 |
| Surface Resistivity | >10^6 MΩ | — | IPC-TM-650 2.5.17 |
| Dielectric Breakdown Voltage | >40 kV/mm | — | IPC-TM-650 2.5.6 |
| Arc Resistance | >60 sec | — | ASTM D495 |
The Dk of 3.3–3.5 at 10 GHz is notably low for an epoxy-based laminate. Most modified epoxy systems sit in the 3.6–3.9 range at this frequency. The lower Dk has a practical benefit beyond just insertion loss — it means slightly wider traces for the same impedance target, which helps with etch tolerance and reduces sensitivity to copper roughness effects.
The Dk stability from 1 GHz to 28 GHz is also worth noting. The drift from ~3.6 at 1 GHz to ~3.4 at 28 GHz is modest and predictable, which means your field solver models hold up well across the frequency range of interest for most 5G and high-speed digital applications.
Insertion Loss Calculation: NPG-198 vs Common Alternatives
To make the Df numbers concrete, here’s a calculated insertion loss comparison for a 50-ohm stripline trace at various frequencies. These are dielectric loss contributions only, using the simplified formula:
Dielectric Loss (dB/inch) ≈ 2.3 × Df × √Dk × f(GHz)
| Material | Df @ 10 GHz | Dk @ 10 GHz | Loss @ 10 GHz (dB/in) | Loss @ 25 GHz (dB/in) | Loss on 20″ trace @ 25 GHz |
| Standard FR-4 | 0.022 | 4.3 | 1.05 | 2.62 | 52.4 dB |
| Isola FR408HR | 0.010 | 3.65 | 0.44 | 1.10 | 22.0 dB |
| NPG-186 | 0.008 | 3.8 | 0.36 | 0.90 | 18.0 dB |
| NPG-198 | 0.004 | 3.4 | 0.17 | 0.43 | 8.6 dB |
| Megtron 6 | 0.004 | 3.6 | 0.18 | 0.44 | 8.8 dB |
| I-Tera MT40 | 0.0031 | 3.45 | 0.13 | 0.33 | 6.6 dB |
The numbers make the case clearly. On a 20-inch backplane trace at 25 GHz, NPG-198 produces about 8.6 dB of dielectric loss versus 22 dB for FR408HR. That’s 13+ dB of margin recovered just from the material choice, before any other optimization. For a 400G link with a total insertion loss budget of 28–35 dB, that margin is the entire design.
Thermal and Mechanical Properties of NPG-198
High-frequency performance is the headline, but a laminate that can’t survive fabrication or field deployment is useless. NPG-198’s thermal and mechanical specs are where it earns its place in demanding applications.
| Property | Value | Test Method |
| Glass Transition Temperature (Tg) | 195 – 210°C | DSC / TMA |
| Decomposition Temperature (Td) | &²µ³Ù;350°°ä | TGA (5% weight loss) |
| T-288 (time to delamination at 288°C) | >60 min | IPC-TM-650 2.4.24.1 |
| T-300 (time to delamination at 300°C) | >20 min | IPC-TM-650 2.4.24.1 |
| CTE Z-axis (below Tg) | 30 – 40 ppm/°C | TMA |
| CTE Z-axis (above Tg) | 200 – 250 ppm/°C | TMA |
| CTE X-axis | 13 – 15 ppm/°C | TMA |
| CTE Y-axis | 13 – 15 ppm/°C | TMA |
| Water Absorption | <0.12% | IPC-TM-650 2.6.2.1 |
| Flexural Strength (Machine Direction) | >480 MPa | IPC-TM-650 2.4.4 |
| Flexural Strength (Cross Direction) | >440 MPa | IPC-TM-650 2.4.4 |
| Peel Strength (1 oz copper) | >1.0 N/mm | IPC-TM-650 2.4.8 |
| Flammability Rating | UL 94 V-0 | UL 94 |
The Tg of 195–210°C is among the highest available in epoxy-based laminates. This matters for two reasons. First, lead-free assembly with peak reflow temperatures of 250–260°C puts significant thermal stress on the laminate. A higher Tg means the resin stays in its glassy state longer during the reflow excursion, reducing the risk of delamination and via barrel cracking. Second, for boards that operate at elevated ambient temperatures — server rooms, outdoor 5G equipment, industrial environments — a higher Tg provides more headroom before the material’s mechanical properties begin to degrade.
The T-288 performance of >60 minutes is exceptional. This is the metric that matters most for sequential lamination processes used in HDI construction. Each lamination cycle exposes the inner layers to press temperatures near or above 200°C. A material that delaminates at T-288 in 10–15 minutes won’t survive 4–6 sequential lamination cycles. NPG-198’s >60 minute T-288 performance means it can handle the most demanding HDI constructions without reliability concerns.
Z-Axis CTE and Microvia Reliability
The Z-axis CTE of 30–40 ppm/°C below Tg is one of NPG-198’s strongest mechanical attributes. For context, standard FR-4 typically runs 50–70 ppm/°C in the Z-axis. The lower Z-axis CTE directly reduces thermal stress on via barrels and microvia structures during temperature cycling.
For HDI boards with laser-drilled microvias in the 75–100 µm diameter range, this matters enormously. The copper barrel in a microvia is thin — often just 10–15 µm — and the stress from Z-axis expansion during thermal cycling is the primary failure mechanism. Lower Z-axis CTE means longer fatigue life and better reliability in applications with wide operating temperature ranges or frequent thermal cycling.
NPG-198 for HDI and High-Layer-Count PCB Construction
The Nanya NPG-198 ultra low loss PCB material is specifically engineered for advanced HDI constructions. Here’s what that means in practice.
Sequential Lamination Capability
NPG-198 supports multiple sequential lamination cycles without delamination risk. This is essential for any-layer HDI constructions where 4–6 press cycles are required to build up the full stackup. The combination of high Tg, excellent T-288 performance, and low water absorption makes NPG-198 one of the more reliable choices for these demanding constructions.
Microvia and Laser Drilling Performance
| Via Type | Capability | Notes |
| Mechanical through-hole | Standard | Compatible with standard carbide tooling |
| CO2 laser microvia | 75–150 µm | Good hole wall quality |
| UV-YAG laser microvia | 50–75 µm | Recommended for finest features |
| Back-drilling | Yes | Compatible with standard back-drill processes |
| Via-in-pad | Yes | Requires filled/capped via process |
| Blind/buried vias | Yes | Standard sequential lamination process |
| Any-layer HDI | Yes | Full qualification |
The UV-YAG laser performance for 50–75 µm microvias is particularly relevant for the densest HDI designs targeting mobile and wearable applications, though NPG-198’s primary market is networking and infrastructure hardware where 75–100 µm microvias are more typical.
Recommended Stackup Configurations
For 100G and 400G networking applications, typical NPG-198 stackups run 16–32 layers with the following general structure:
Signal layers: 1 oz copper (35 µm), sometimes 0.5 oz for fine-pitch differential pairs
Power/ground planes: 1–2 oz copper
Core thickness: 0.1–0.2 mm for HDI signal layers, 0.2–0.4 mm for power/ground cores
Prepreg: 1080 or 2116 glass style for controlled-impedance layers
Total board thickness: 2.4–3.2 mm for 20–32 layer constructions
Impedance targets for common interfaces on NPG-198 (Dk ≈ 3.4 at 10 GHz):
| Interface | Impedance Target | Typical Trace Width (stripline, 0.1mm dielectric) |
| Single-ended 50Ω | 50 Ω ± 5% | ~0.12–0.15 mm |
| Differential 100Ω | 100 Ω ± 5% | ~0.10 mm / 0.10 mm gap |
| Differential 85Ω | 85 Ω ± 5% | ~0.12 mm / 0.08 mm gap |
| Coplanar waveguide 50Ω | 50 Ω ± 5% | Design-specific |
Nanya NPG-198 vs Competing Ultra-Low-Loss Laminates
Understanding where NPG-198 sits in the competitive landscape helps justify the material choice to procurement teams and program managers.
| Material | Manufacturer | Dk @ 10 GHz | Df @ 10 GHz | Tg (°°ä) | Td (°°ä) | Halogen-Free | Cost Index |
| NPG-198 | Nanya | 3.3–3.5 | 0.003–0.005 | 195–210 | >350 | Yes | 1.0x |
| NPG-186K | Nanya | 3.5–3.7 | 0.004–0.006 | 185–200 | >340 | Yes | 0.85x |
| Megtron 6 | Panasonic | 3.6 | 0.004 | 185 | >340 | Yes | 1.6x |
| Megtron 7 | Panasonic | 3.4 | 0.002 | 185 | >340 | Yes | 2.2x |
| I-Tera MT40 | Isola | 3.45 | 0.0031 | 200 | >340 | Yes | 1.7x |
| TU-872 SLK SP | TUC | 3.3 | 0.004 | 200 | >350 | Yes | 1.0x |
| Ventec VT-901 | Ventec | 3.5 | 0.005 | 185 | >330 | Yes | 0.95x |
| Rogers 4350B | Rogers | 3.48 | 0.0037 | >280 | — | No | 3.5x |
NPG-198 competes most directly with TUC TU-872 SLK SP on both performance and price. Against Megtron 6, it offers comparable Df at roughly 60% of the cost. Against I-Tera MT40, it’s slightly higher Df but significantly lower cost and better thermal performance (higher Tg and Td).
The comparison with Megtron 7 is interesting — Megtron 7 achieves lower Df (0.002) but at more than double the cost of NPG-198. For most 10–28 GHz applications, the difference between Df 0.004 and Df 0.002 is measurable but not design-critical. Megtron 7 makes sense for the most demanding 56 Gbps PAM4 backplanes and mmWave antenna arrays. NPG-198 covers the vast majority of 10G–400G networking applications at a much more practical price point.
Target Applications for Nanya NPG-198 Ultra Low Loss PCB
100G and 400G Ethernet Switch Fabrics
This is the core application for NPG-198. High-radix switch ASICs like Broadcom Tomahawk and Tofino series drive 25.6 Tbps and higher aggregate bandwidth through dense PCB interconnects. The SerDes lanes running at 25–56 Gbps per lane across 15–25 inch traces on a switch fabric board are exactly the scenario where NPG-198’s Df of 0.003–0.005 makes the difference between a working design and one that requires expensive retimers or signal conditioning.
5G Base Station Radio Units and Fronthaul
5G NR operates across sub-6 GHz and mmWave bands up to 39 GHz. Radio unit (RU) boards handling beamforming, digital predistortion, and fronthaul interfaces need laminates that maintain consistent Dk and low Df across this frequency range. NPG-198’s Dk stability from 1 GHz to 28 GHz and its Df of ~0.004 at 28 GHz make it well-suited for these applications.
High-Performance Computing and AI Accelerator Boards
GPU and AI accelerator boards running NVLink, PCIe Gen 5, and CXL interfaces at 32–64 GT/s need low-loss laminates for the high-speed interconnects between processors, memory, and I/O. NPG-198 handles these interfaces comfortably while providing the thermal stability needed for the high-power-density environments typical of AI hardware.
Aerospace and Defense High-Frequency Electronics
Radar signal processing boards, electronic warfare systems, and satellite communication hardware operating in the X-band (8–12 GHz), Ku-band (12–18 GHz), and Ka-band (26–40 GHz) benefit from NPG-198’s combination of low Df, stable Dk, high Tg, and halogen-free chemistry. The halogen-free formulation is increasingly required for defense applications with environmental compliance requirements.
Optical Transport Network Line Cards
OTN line cards handling 100G, 400G, and 800G coherent optical interfaces require high-speed electrical interconnects between the DSP, optical module, and backplane connectors. These boards often run 28–32 layers with multiple sequential lamination cycles — exactly the construction where NPG-198’s thermal stability and HDI capability provide the most value.
Fabrication and Processing Guidelines for NPG-198
Lamination Parameters
NPG-198 requires slightly elevated press temperatures compared to standard FR-4, typically 185–195°C peak temperature with a cure time of 60–90 minutes. Fabricators with experience running Megtron 6 or I-Tera MT40 will find NPG-198’s process requirements familiar. The key parameters to control are:
Heating rate: 2–3°C/min to avoid resin flow issues
Peak temperature: 185–195°C (confirm with specific prepreg datasheet)
Pressure: 250–350 psi depending on layer count and prepreg style
Vacuum: >28 inHg during press cycle
Copper Foil Selection and Surface Roughness
At 10 GHz and above, conductor loss from copper surface roughness becomes a significant contributor to total insertion loss. NPG-198 is typically paired with low-profile (LP) or very-low-profile (VLP) copper foils to minimize the roughness contribution. Standard electrodeposited (ED) copper with Rz of 5–7 µm adds measurable insertion loss at 25 GHz. LP copper (Rz 2–3 µm) or VLP copper (Rz <1.5 µm) is recommended for traces carrying signals above 15 GHz.
Surface Finish Recommendations
| Surface Finish | Compatibility | Notes |
| ENIG | Excellent | Most common choice for HDI |
| ENEPIG | Excellent | Preferred for wire bonding applications |
| Immersion Silver | Good | Good RF performance, shorter shelf life |
| Immersion Tin | Good | Good for fine-pitch SMT |
| OSP | Good | Cost-effective, limited shelf life |
| HASL (Lead-free) | Acceptable | Not recommended for fine-pitch HDI |
ENIG is the most common surface finish for NPG-198 boards due to its flat surface, good solderability, and compatibility with the fine-pitch components typical of high-speed networking hardware. The low water absorption of NPG-198 (<0.12%) helps maintain ENIG adhesion quality and reduces black pad risk.
Design Best Practices for NPG-198 High-Speed Designs
A few practical guidelines that apply specifically to NPG-198 designs at 10 GHz and above.
Via stub management becomes critical above 15 GHz. Unterminated via stubs create resonances that appear as notches in the insertion loss response. For NPG-198 designs running 25 Gbps and above, back-drilling to within 5–8 mils of the signal layer is standard practice. Via-in-pad with filled and capped vias eliminates the stub entirely and is preferred for the highest-frequency signals.
Differential pair routing on NPG-198 should maintain tight coupling throughout the trace length. Edge-to-edge spacing of 1x trace width or less is recommended. Avoid routing differential pairs through areas with split reference planes or near board edges where return current paths are disrupted. The low Df of NPG-198 means you’re not fighting material loss, so you can optimize routing for crosstalk and return path integrity instead.
Fiber weave effect is a consideration at 28 GHz and above. The periodic structure of the woven glass fabric creates localized Dk variations that can cause differential skew and mode conversion. For the most sensitive signals, routing differential pairs at 0°, 45°, or 90° to the glass weave direction, or specifying spread-glass or flat-glass fabric styles, reduces this effect.
Impedance modeling with NPG-198 should use the frequency-specific Dk values rather than a single broadband value. Most modern field solvers support frequency-dependent material models. Using Dk = 3.6 at 1 GHz and Dk = 3.4 at 10 GHz gives more accurate impedance predictions than using a single value across the full frequency range.