NP-170 PCB Material: NPG-170N, D and D(C) Grades Compared

NP-170 is shorthand for Nan Ya Plastics’ Tg 170 °C epoxy laminates, not a grade you can order by that name. Nan Ya’s current catalogue lists three 170 °C families: NPG-170N, NPG-170D (sold as NPG-170DR and NPG-170DTL) and NPG-170D(C). All have a DSC Tg of 170 ± 5 °C, but they differ in decomposition temperature (360–385 °C), thermal-stress time at 288 °C (300 s or 600 s) and dielectric loss, so a drawing that says only “NP-170” leaves the most important choice to the fabricator. Pick the grade from the comparison below and write the full code on the drawing.

Values are Nan Ya’s typical datasheet figures (sheets revised 2025–2026), not guaranteed minimums.

What Is NP-170?

It is a search and purchasing nickname for a Tg 170 laminate from Nan Ya Plastics, one of the large Taiwanese copper-clad laminate makers. Nan Ya’s own Tg and loss product catalogue does not list a product called NP-170; it lists NPG-170N, NPG-170D and NPG-170D(C), and the NPG-170D datasheet splits into NPG-170DR and NPG-170DTL. Each code has its own resin system, datasheet, prepreg list and press cycle.

All three datasheets reference IPC-4101E specification sheets 127 and 128 and UL file E98983. IPC-4101 is the base-material specification for rigid and multilayer boards and covers both laminate and prepreg (IPC-4101E contents). A slash-sheet number tells you the material class; it does not tell you which of the four Nan Ya grades you will receive, which is why the full code matters.

If you are still choosing a temperature class rather than a product, start with our guide to FR-4 Tg grades and come back once Tg 170 is settled; the PCB materials guide compares laminate families more broadly.

How Do the Four NPG-170 Grades Compare?

They share a Tg but not much else. The datasheet values that separate them are:

Sources: Nan Ya datasheets for NPG-170N, NPG-170DR/DTL and NPG-170D(C).

Read the dielectric rows with their test conditions. NPG-170N and DR are reported at 1 GHz; DTL and D(C) are reported at 10 GHz by cavity resonator at a stated resin content (50% and 70%). The D(C) peel figure is measured on a different copper foil type than the others, so a lower number there is not directly comparable. For impedance and loss modeling, ask the fabricator for construction-specific Dk values rather than taking a headline value from the first page.

Which NPG-170 Grade Fits Your Board?

Choose by the requirement that is hardest to meet, not by the Tg, because the Tg is the same for all four.

• Conventional multilayer, standard-loss signals: NPG-170N. Its datasheet describes a halogen-free formulation (no halogen, antimony or red phosphorus) with UL 94 V-0.
• Thick boards, many reflow or rework passes, high aspect-ratio vias: one of the D grades. Doubling the 288 °C thermal-stress time and raising Td by 20–25 °C buys margin where plated holes see the most strain.
• Long or fast digital channels: NPG-170DTL or NPG-170D(C), whose Df of about 0.007–0.008 at 10 GHz sits well below the standard grade.
• Boards where Z-axis expansion drives via reliability: NPG-170D(C), with the lowest published 50–260 °C expansion (2.1%).
• Humid environments or moisture-sensitive builds: NPG-170DR, the only grade with water absorption near 0.1%.

When none of these fits, compare Tg 170 alternatives from other laminate makers on the same test methods. Our comparisons of S1170G and S1000-2M, the IT-170 variants and TU-768 cover the usual candidates.

Does Tg 170 Mean the Board Survives Lead-Free Assembly?

Not by itself. Tg marks where the resin softens; lead-free reflow peaks around 245–260 °C, well above any Tg 170 material, so what matters is how much the board expands above Tg and how long the resin resists decomposition and delamination. That is why Td, Z-axis expansion and the 288 °C thermal-stress time are the numbers to compare.

As an example of how to read the table: a 6-layer, 1.6 mm board with standard holes and two reflow passes is the kind of build a standard Tg 170 grade such as NPG-170N is usually chosen for. A 2.4 mm, 16-layer board with 0.25 mm holes, a planned rework and a second-side reflow is where the D grades’ ≥600 s and higher Td start to matter. Neither figure is a promise of a number of reflow cycles; the finished board still needs coupons and microsections to prove the plated holes.

The UL data on all three sheets also sets limits you should not exceed in assembly: a solder limit of 288 °C for 30 s and a maximum operating temperature (MOT) of 130 °C. A board specified for continuous operation above 130 °C needs a material with a higher UL rating, whatever its Tg.

Which Cores and Prepregs Are Available?

NPG-170N cores run from 0.05 to 1.2 mm; NPG-170D and D(C) cores from 0.05 to 1.0 mm. Copper options on all three are H, 1, 2 and 3 oz (17, 35, 70 and 102 µm), on master sheets of 48.8 × 36.6, 40.5 or 42.5 in, with thickness tolerance to IPC-4101E Class C/M.

Prepreg pressed thickness is published per glass style and resin content, which is what a stackup is built from. A few examples from the datasheets:

Two details catch stackups out. Nan Ya does not recommend glass styles coarser than 2116 for NPG-170DR/DTL, so a 7628-based stackup has to change if you move from N to D. And the NPG-170N prepreg table states its pressed thickness at 100% residual copper; the D tables do not state the same condition, so pressed thickness on a sparse signal layer will come out thinner than listed for both.

Prepreg storage is the same for all three: below 5 °C for 180 days, or below 23 °C and 50% RH for 90 days.

How Is NPG-170 Laminated?

With a press cycle that differs by grade, which is another reason not to mix them. The datasheet windows are:

The cure step is the one to watch: NPG-170D(C) needs material temperatures above 200 °C for 90 minutes, which some press lines run as a separate program. The slow cooling rate limits bow and twist, which is worth checking on thin, asymmetric stackups.

After pressing, drilling, desmear and plating parameters come from the fabricator’s own qualification for the glass style and thickness; the laminate datasheet does not set them.

How Should You Specify NP-170 on a Drawing?

With the full grade code, or with measurable minimums if you will accept another maker’s material. Typical fabrication notes:

Ask the fabricator to put the proposed core and prepreg codes, glass styles, resin contents and pressed thicknesses on the stackup it returns with the quote. That one page shows whether you are getting NPG-170N or a D grade, and whether a 7628 layer slipped into a D-grade build. Keep it with the purchase order so a later lot cannot change grade without a new approval.

How Can We Help?

QueenEMS builds rigid multilayer boards from 1 to 40 layers, from 0.2 to 6.0 mm thick, with impedance control to ±5% on high-speed designs. Send the stackup with the Nan Ya grade you have chosen, or the minimum properties you will accept, and our engineers will return the proposed cores, prepregs and pressed thicknesses for you to approve before release. Pricing for the bare boards follows within 2 hours; for builds like this see our multilayer PCB manufacturing page, or upload the files for a free DFM check.

Conclusion

Write the full grade on the drawing, check the stackup the fabricator returns, and do not mix grades in one build. Contact us with your Gerber files, stackup, chosen grade and quantities for a quote.

FAQ

What is NPG-170N? A Nan Ya Plastics glass-epoxy, halogen-free FR-4 laminate with a DSC Tg of 170 ± 5 °C, Td of 360 °C and Dk of 4.1–4.3 at 1 GHz.

What is the difference between NPG-170N and NPG-170D? The D family has a higher Td (380 °C), twice the 288 °C thermal-stress time (≥600 s) and lower dielectric loss, at the cost of a different press cycle and a limit on coarse glass styles.

Is NPG-170D(C) the same as NPG-170D? No. It has its own datasheet, a higher cure temperature (above 200 °C), slightly higher Dk and Df than DTL at 10 GHz, and the lowest published Z-axis expansion of the family.

Is NP-170 halogen-free? NPG-170N is described as halogen-free on its datasheet. Check the declaration for the exact grade you order, since “NP-170” does not identify one.

Can I put “NP-170 or equivalent” on a drawing? You can, but it lets the fabricator choose among four grades with different thermal and electrical properties. Name the grade, or add measurable minimums for Tg, Td, T288 and loss.