Panasonic PCB Material Part Number Guide: How to Decode R-Series Part Numbers

When you’re designing high-speed backplanes or high-reliability automotive modules, the choice of substrate is often the difference between a functional prototype and a $50,000 pile of scrap. Panasonic’s R-series materials have become the industry gold standard, but for many engineers, the part numbers can feel like a cryptic language.

In this guide, we will strip away the mystery. As an engineer who has spent years staring at stackups, I can tell you that understanding the “R-number” logic is the fastest way to navigate the Panasonic catalog and ensure your design hits its signal integrity and thermal targets.

The Logic of the Panasonic R-Series Part Number Guide

Panasonic’s naming convention is actually quite structured once you see the pattern. Most part numbers are 4-digit codes preceded by “R-“. These digits aren’t random; they often categorize the material by resin type, speed, and application.

Understanding the Core Numbering Scheme

The first two digits generally identify the material family or series. For example:

R-1xxx Series: Typically represents standard and high-reliability FR-4 materials (e.g., R-1755V).

R-5xxx Series: Dedicated to high-speed, low-loss materials, primarily the MEGTRON and XPEDION lines (e.g., R-5775, R-5515).

R-Fxxx Series: Indicates flexible materials under the FELIOS brand (e.g., R-F775).

Laminate vs. Prepreg: The “10-Digit” Difference

One of the most common points of confusion is the relationship between the laminate (the core) and the prepreg (the bonding sheet). In many Panasonic families, there is a specific offset in the part numbers:

Material Type	Digit Pattern	Example (MEGTRON 6)	Example (Automotive)
Laminate (Core)	R-5x7x / R-1x5x	R-5775	R-1755V
Prepreg (B-Stage)	R-5x2x / R-1x0x	R-5620	R-1650V

As a rule of thumb for MEGTRON, if the second digit is a 7, it’s usually the laminate; if it’s a 6, it’s the prepreg. For standard FR-4, a 7 often indicates laminate while a 6 indicates prepreg.

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Decoding the Most Popular R-Series Materials

Let’s look at the “Rockstars” of the Panasonic lineup. If you can decode these, you can handle almost anything in their portfolio.

1. The MEGTRON Family (R-57xx)

The MEGTRON series is the backbone of the AI and networking world. The numbers here correlate directly with the “generation” of the material.

R-5725 (MEGTRON 4): The legacy low-loss choice for PCIe Gen 3.

R-5775 (MEGTRON 6): The industry workhorse for 28Gbps and 56G PAM4.

R-5785 (MEGTRON 7): The ultra-low loss standard for 112G PAM4.

R-5795 (MEGTRON 8): The bleeding edge for 224Gbps and AI clusters.

2. The High-Reliability Series (R-17xx)

Designed for automotive and industrial use where thermal cycling is the primary concern.

R-1755V (HIPER V): High-Tg material with excellent CAF resistance and Z-axis stability.

R-1755M: A “Mid-Tg” version of the HIPER series, optimized for cost and reliability in automotive sensors.

3. The RF Specialist (XPEDION)

R-5515 (XPEDION 1): Unlike MEGTRON, which is digital-focused, XPEDION is an RF material designed for 77GHz radar and 5G antennas. Its number breaks the MEGTRON pattern to distinguish its phase-stability properties.

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Suffixes and Identifiers: The Hidden Details

Sometimes you will see letters in parentheses after the part number. These are critical for your fabricator to know.

(N): Often denotes “Low Dk Glass Cloth.” Essential for reducing skew in high-speed differential pairs.

(G) or (GH): Usually indicates “Green” (Halogen-Free) variants.

(V): High-reliability automotive designation (seen in R-1755V).

(X): Sometimes used for “Next Generation” or modified versions of an existing part number (e.g., R-5515X).

Laminate and Prepreg Comparison Table

Series	Laminate Part #	Prepreg Part #	Typical Application
MEGTRON 4	R-5725	R-5620	Mid-speed servers, PCIe 3.0
MEGTRON 6	R-5775	R-5670	25G-56G Networking, Switches
MEGTRON 7	R-5785	R-5680	112G PAM4, Core Routers
MEGTRON 8	R-5795	R-5690	224G, AI Accelerators
HIPER V	R-1755V	R-1650V	Automotive ECUs, Industrial
Standard FR-4	R-1766	R-1661	General Multi-layer, Appliances

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Design Engineer’s Strategy: How to Select and Specify

When I’m specifying a Panasonic PCB on a fabrication drawing, I don’t just write “R-5775.” That’s a recipe for a call from the board house asking for clarification.

1. Specify the Full Package

Always list both the laminate and the matching prepreg. For MEGTRON 6, your note should read: “Base Material: Panasonic MEGTRON 6 (Laminate R-5775, Prepreg R-5670).” This ensures the resin systems are perfectly matched during the lamination cycle.

2. Copper Foil Matters

Panasonic materials are often paired with specific copper foils like H-VLP (Hyper Very Low Profile) or VLP. You should include the copper type in your notes, especially for R-5785 (MEGTRON 7) and above, as the signal travels on the copper “skin” at those frequencies.

3. Glass Style

If you are worried about “Fiber Weave Effect” (skew), make sure to specify the glass style (e.g., 1067, 1078, 1080). For high-speed layers, request Spread Glass versions of the prepreg.

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Useful Resources for Part Number Verification

To stay updated, I recommend these databases:

Panasonic Industry Electronic Materials Portal: The ultimate source for technical datasheets and the most current R-series part numbers. Panasonic Technical Data.

UL Product iQ: Search for Panasonic’s UL File (E41429) to see which part numbers are registered for flammability and safety.

Signal Integrity Journal: Excellent for whitepapers on why you might choose R-5785 over R-5775 for 112G designs.

IPC-4101 Standards: Panasonic materials are mapped to IPC slash sheets (e.g., R-1755V meets /126 and /97).

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Frequently Asked Questions (FAQs)

1. Is R-1755 the same as MEGTRON?

No. R-1755 (HIPER V) is a high-reliability glass epoxy material intended for automotive and industrial use. MEGTRON (R-57xx) is a polyphenylene ether (PPE) resin material intended for high-speed digital communications.

2. Why does the prepreg part number differ from the laminate?

Prepreg (R-16xx or R-56xx) is an uncured “B-Stage” resin sheet, while Laminate (R-17xx or R-57xx) is a fully cured core with copper. They have different part numbers because they are different physical products, even though they share the same resin chemistry.

3. What does the “R-” actually stand for?

While not officially stated, in the industry “R” is often associated with “Resin” or simply acts as the standard prefix for Panasonic’s rigid laminate portfolio.

4. Can I use R-1566 prepreg with R-1755V laminate?

Generally, no. You should never mix different resin systems in a stackup unless you have performed a hybrid lamination study. Stick to the matched pairs (e.g., R-1755V with R-1650V) to ensure the CTE and lamination temperatures are compatible.

5. How do I know if a part number is Halogen-Free?

Typically, Panasonic’s halogen-free materials have distinct part numbers (like R-1566 or R-5375). Always check the “Halogen-free” section of the Panasonic product finder to confirm.

Summary for the Engineering Review

Decoding the Panasonic R-series PCB part number guide is about seeing the relationship between the material “generation” and its physical form (laminate vs. prepreg).

R-5xxx is your high-speed lane (MEGTRON).

R-1xxx is your reliability lane (HIPER/FR-4).

Laminate ends in 5 or 7; Prepreg ends in 0 or 1.

By specifying the correct R-number on your fabrication drawings, you remove ambiguity, improve yields, and ensure your hardware survives the environment it was designed for.