Complete guide to Panasonic R-1766 glass epoxy PCB laminate 鈥� specs, Tg, Dk/Df tables, prepreg R-1661 data, applications, and fabrication tips for PCB engineers.
If you’ve spent any time sourcing laminate materials for multi-layer PCB production, you’ve almost certainly come across the Panasonic R-1766 glass epoxy PCB laminate. It sits in a sweet spot that a lot of engineers are looking for 鈥� solid thermal performance, reliable electrical behavior, and broad compatibility with standard FR-4 fabrication processes 鈥� without the cost premium of high-frequency specialty materials like the Megtron series. This guide walks through everything you need to know about R-1766, from raw property data to stackup considerations, with the kind of practical context that actually helps during material selection.
What Is the Panasonic R-1766? An Overview
The R-1766 (designated R-1766(GH) as a laminate) is a general-purpose glass epoxy multi-layer circuit board material manufactured by Panasonic Industry Co., Ltd. through its Electronic Materials Business Division. It is paired with the R-1661(GZ) prepreg for multi-layer construction, and together they form a matched system designed for standard to mid-level demanding PCB applications.
In practical terms, it’s a mid-Tg FR-4-class laminate. It is not a low-loss or ultra-low-Dk specialty material 鈥� that’s what the Panasonic PCB Megtron family is for. The R-1766 is the material you reach for when you need consistent, reliable FR-4-level performance with the confidence of a tier-one supplier behind it.
R-1766 in the Panasonic Portfolio
Panasonic’s electronic materials lineup spans from general-purpose FR-4 equivalents up to ultra-low-loss MEGTRON 8 (Tg 220掳颁, Dk 3.1, Df 0.0012). The R-1766 sits near the general-purpose end of that spectrum 鈥� it’s the everyday workhorse, not the exotic high-performance material. Understanding that positioning helps frame every specification comparison below.
Full Technical Specifications of Panasonic R-1766(GH) Laminate
The table below compiles the official typical values from the Panasonic datasheet (July 2022, No. 22070146). Note that these are typical values, not guaranteed values 鈥� always verify with the full datasheet before locking your design.
Thermal Properties
| Property | Units | Test Method | Condition | Typical Value |
| Glass Transition Temp (Tg) 鈥� DSC | 掳颁 | DSC | As received | 140 |
| Glass Transition Temp (Tg) 鈥� TMA | 掳颁 | TMA | As received | 140 |
| Glass Transition Temp (Tg) 鈥� DMA | 掳颁 | DMA | As received | 150 |
| Thermal Decomposition Temp (Td) | 掳颁 | TGA | As received | 315 |
| T288 (without Cu) | min | IPC TM-650 2.4.24.1 | As received | 5 |
| T288 (with Cu) | min | IPC TM-650 2.4.24.1 | As received | 1 |
| CTE 伪1 鈥� X-axis | ppm/掳颁 | IPC TM-650 2.4.24 | < Tg | 11鈥�13 |
| CTE 伪1 鈥� Y-axis | ppm/掳颁 | IPC TM-650 2.4.24 | < Tg | 13鈥�15 |
| CTE 伪1 鈥� Z-axis | ppm/掳颁 | IPC TM-650 2.4.24 | < Tg | 65 |
| CTE 伪2 鈥� Z-axis | ppm/掳颁 | IPC TM-650 2.4.24 | > Tg | 270 |
The Tg of 140掳颁 (DSC/TMA) is the number to pay attention to most here. If your assembly process involves lead-free reflow 鈥� typically peaking at 260掳颁 鈥� you need to think carefully about how many thermal cycles your board will see and whether the T288 of 5 minutes (no copper) gives you enough headroom. For most standard consumer and industrial applications that go through one or two reflow passes, it’s workable. If you’re dealing with multiple lamination cycles or aggressive rework environments, you’re better served by a higher-Tg material.
Electrical Properties
| Property | Units | Test Method | Condition | Typical Value |
| Volume Resistivity | 惭惟路肠尘 | IPC TM-650 2.5.17.1 | C-96/35/90 | 1 脳 10鈦� |
| Surface Resistivity | 惭惟 | IPC TM-650 2.5.17.1 | C-96/35/90 | 1 脳 10鈦� |
| Dielectric Constant (Dk) @ 1 MHz | 鈥� | IPC TM-650 2.5.5.9 | C-24/23/50 | 4.6 |
| Dielectric Constant (Dk) @ 1 GHz | 鈥� | IPC TM-650 2.5.5.9 | C-24/23/50 | 4.3 |
| Dissipation Factor (Df) @ 1 MHz | 鈥� | IPC TM-650 2.5.5.9 | C-24/23/50 | 0.014 |
| Dissipation Factor (Df) @ 1 GHz | 鈥� | IPC TM-650 2.5.5.9 | C-24/23/50 | 0.016 |
A Df of 0.014鈥�0.016 puts the R-1766 squarely in standard FR-4 territory. For reference, general-purpose FR-4 from common suppliers typically lands around 0.015 Df. This is not a material for differential pairs running at multi-gigabit speeds or RF traces above a few hundred MHz 鈥� signal loss will become a limiting factor. For standard digital designs at moderate speeds, these numbers are perfectly adequate.
Physical Properties
| Property | Units | Test Method | Condition | Typical Value |
| Water Absorption | % | IPC TM-650 2.6.2.1 | D-24/23 | 0.14 |
| Peel Strength (1 oz) | kN/m | IPC TM-650 2.4.8 | As received | 2.0 |
| Flammability | 鈥� | UL C-48/23/50 | 鈥� | 94V-0 |
Water absorption of 0.14% is quite low and contributes to dimensional stability and resistance to delamination during moisture-sensitive assembly steps. The UL 94V-0 flammability rating is a standard requirement for most product categories and confirms R-1766 passes without question.
Laminate Thickness vs. Dk/Df (R-1766(GH) 鈥� 1 MHz to 1 GHz)
This is the kind of data PCB designers actually need when building a stack-up. The Dk value shifts depending on the prepreg style and thickness:
| Nominal Thickness (mil) | Cloth Style | Resin Content (%) | Dk @ 1 MHz | Dk @ 1 GHz | Df @ 1 MHz | Df @ 1 GHz |
| 2.5 | 1080 | 57 | 4.2 | 3.9 | 0.016 | 0.018 |
| 4 | 2116 | 43 | 4.6 | 4.3 | 0.014 | 0.016 |
| 6 | 1501 | 42 | 4.6 | 4.3 | 0.014 | 0.016 |
| 8 | 7628 | 43 | 4.6 | 4.3 | 0.014 | 0.016 |
| 12 | 1501 | 42 | 4.6 | 4.3 | 0.014 | 0.016 |
| 16 | 7628 | 43 | 4.6 | 4.3 | 0.014 | 0.016 |
| 20 | 7628/2116 | 43 | 4.6 | 4.3 | 0.014 | 0.016 |
| 24 | 7628 | 43 | 4.6 | 4.3 | 0.014 | 0.016 |
Notice that the thin 1080-style prepreg at 2.5 mil comes in with a lower Dk (4.2 at 1 MHz) due to the higher resin content (57%). This matters for controlled-impedance trace calculations 鈥� if you’re mixing prepreg styles in a stack-up, don’t assume a flat Dk across every dielectric layer.
Panasonic R-1661(GZ) Prepreg 鈥� Companion Material
The R-1766 laminate is paired with the R-1661(GZ) prepreg for multi-layer builds. The prepreg data covers a broader range of cloth styles including 1080, 2116, 1501, 1504, and 7628. Resin content ranges from 42% to 70% depending on the cloth, with corresponding Dk values (at 1 GHz) ranging from 3.5 to 4.3.
When designing multi-layer stack-ups using R-1766/R-1661, keep these matched-set properties in your simulation models 鈥� using generic FR-4 Dk values for the prepreg layers will give you inaccurate impedance predictions.
Where R-1766 Fits: Target Applications
The Panasonic R-1766 glass epoxy PCB material is explicitly classified as a general-purpose multi-layer material. That label covers a wider range of boards than you might think:
Consumer Electronics 鈥� 吃瓜tv appliances, audio/video equipment, white goods. The combination of UL 94V-0 flammability, solid insulation properties, and cost-effective FR-4-class processing makes R-1766 suitable for high-volume consumer product PCBs where cost per square meter matters.
Industrial Control Boards 鈥� PLCs, motor drivers, power supply controllers, and similar industrial products operating in moderate temperature environments (well below 140掳颁 ambient). The low CTE in X/Y axes (11鈥�15 ppm/掳颁) helps with dimensional stability during thermal cycling.
ICT Infrastructure 鈥� Network switches, routers, and server backplanes running standard digital signaling. If your design doesn’t push past 1鈥�2 Gbps per channel, R-1766 can serve you well. Above that range, consider upgrading to the Megtron 4 or Megtron 6 family.
Automotive Support Electronics 鈥� Not for under-hood or direct powertrain applications (Tg of 140掳颁 is too low), but suitable for body electronics, cabin control modules, and infotainment boards where the thermal environment is manageable.
LED and Display Boards 鈥� Light control PCBs and driver boards for mid-range LED systems.
How R-1766 Compares to Other Materials
R-1766 vs. Standard Generic FR-4
| Parameter | Panasonic R-1766 | Generic FR-4 (typical) |
| Tg (DSC) | 140掳颁 | 130鈥�140掳颁 |
| Td | 315掳颁 | ~300掳颁 |
| Dk @ 1 GHz | 4.3 | 4.3鈥�4.8 |
| Df @ 1 GHz | 0.016 | 0.015鈥�0.022 |
| Water Absorption | 0.14% | 0.10鈥�0.20% |
| Source Quality | Panasonic tier-1 | Varies widely |
| Datasheet Depth | Extensive (multi-GHz data) | Often minimal |
The headline spec values are similar, but the consistency and supply chain reliability of a Panasonic material over generic FR-4 is a real-world differentiator for production engineers. Panasonic also publishes frequency-resolved Dk/Df data up to 10 GHz 鈥� something generic FR-4 suppliers rarely provide.
R-1766 vs. Panasonic R-1755V (Higher-Tg FR-4)
| Parameter | R-1766(GH) | R-1755V |
| Tg (DSC) | 140掳颁 | 173掳颁 |
| Td | 315掳颁 | 350掳颁 |
| Dk @ 1 GHz | 4.3 | 4.4 |
| Df @ 1 GHz | 0.016 | 0.016 |
| Target Use | General-purpose | High-reliability, lead-free heavy |
If your assembly involves aggressive lead-free processing, multiple reflow passes, or a higher operating temperature ceiling, R-1755V is the next step up within Panasonic’s FR-4-class lineup.
R-1766 vs. Panasonic Megtron 4 (Low-Loss)
| Parameter | R-1766(GH) | Megtron 4 |
| Tg | 140掳颁 | 176掳颁 |
| Dk @ 1 GHz | 4.3 | 3.8 |
| Df @ 1 GHz | 0.016 | 0.005 |
| Td | 315掳颁 | 360掳颁 |
| Cost | Lower | Higher |
| Target Use | General-purpose | High-speed digital |
The Df difference (0.016 vs. 0.005) is where these two materials diverge sharply. At 10 Gbps and above, Megtron 4 is the correct choice. R-1766 is not a low-loss material.
Fabrication and Processing Considerations
Lead-Free Compatibility
The R-1766 is compatible with lead-free soldering processes, though its Tg of 140掳颁 means the headroom above the peak reflow temperature (~260掳颁) is limited. The material’s Td of 315掳颁 and T288 of 5 minutes (without copper) give some buffer, but you should count your reflow passes carefully. Two full lead-free reflow cycles are generally considered the practical limit for Tg-140 materials.
Drilling and Routing
Being an FR-4-class glass-epoxy material, the R-1766 drills and routes with standard carbide tooling and conventional spindle speeds. No exotic process modifications are required 鈥� it integrates into a standard FR-4 production flow.
Sequential Lamination
While the R-1766 supports standard multi-layer lamination processes, engineers considering sequential lamination (for via-in-pad designs or blind/buried via stacks) should carefully evaluate the cumulative thermal exposure. Each lamination cycle adds thermal stress on the dielectric, and the limited T288 of the R-1766 means you typically shouldn’t exceed two lamination cycles without detailed verification.
Panasonic’s Process Guidelines
Panasonic publishes a dedicated Process Guidelines document (covering R-1766/R-1661 among others) that outlines recommended lamination parameters including temperature ramp rates, press cycle durations, and cooling protocols. Consulting that document before finalizing your fabrication spec is strongly recommended.
Useful Resources for R-1766 Engineers
| Resource | Description | Link |
| Official Panasonic R-1766 Datasheet (2022) | Latest IPC-format datasheet with full electrical and thermal data | |
| Panasonic Electronic Materials Product Page | Product listing and download center | |
| IPC TM-650 Test Methods | Reference standard for thermal and electrical property testing | |
| PCB Directory 鈥� R-1766 Listing | Third-party specs and supplier contacts | |
| Panasonic Circuit Board Materials Overview | Full portfolio context |
Frequently Asked Questions About Panasonic R-1766
Is Panasonic R-1766 a true FR-4 material?
Yes, the R-1766 is a glass-fiber-reinforced epoxy laminate classified as an FR-4-grade material. It achieves UL 94V-0 flammability rating and meets the general electrical and mechanical requirements associated with the FR-4 designation. It is not a specialty low-loss or high-frequency material 鈥� it is Panasonic’s general-purpose offering in the glass epoxy multi-layer category.
What is the Tg of the R-1766 and why does it matter?
The R-1766 has a Tg of 140掳颁 as measured by DSC and TMA, and 150掳颁 by DMA. The glass transition temperature defines the point at which the laminate transitions from a rigid, glassy state to a softer, rubbery state 鈥� above Tg, the Z-axis CTE increases dramatically (from 65 ppm/掳颁 to 270 ppm/掳颁), which puts stress on plated-through holes and vias. For lead-free assembly with peak temperatures around 260掳颁, the 140掳颁 Tg is workable for a limited number of reflow passes but is not the highest-Tg option available in the Panasonic range.
Can R-1766 be used for controlled impedance designs?
Yes, with care. The Dk values from the datasheet (4.3鈥�4.6 depending on prepreg style and frequency) are consistent enough for controlled impedance work, provided your simulation tool and fabricator are using the correct thickness- and frequency-specific Dk inputs. Avoid using a single flat Dk value across all layers if you’re mixing prepreg cloth styles.
What prepreg is used with R-1766 in multi-layer construction?
The standard companion prepreg is the R-1661(GZ). Panasonic publishes matched Dk/Df data for both the laminate and prepreg as part of the same datasheet package, which simplifies stack-up modeling. The two materials are processed under the same lamination guidelines.
How does R-1766 compare to other Panasonic materials for cost and performance?
R-1766 is positioned as a cost-effective general-purpose laminate. It is less expensive than higher-Tg Panasonic materials (like R-1755V) and significantly less expensive than the Megtron family. If your application needs Df below 0.010 or Tg above 150掳颁, you’ll need to step up to a more specialized Panasonic material 鈥� but for mainstream multilayer PCB production, R-1766 delivers reliable performance at competitive cost.
Final Engineer’s Perspective
The R-1766 is not a glamorous material 鈥� it doesn’t have the headline specs of Megtron 6 or MEGTRON 8. But that’s not what it’s trying to be. For the tens of thousands of multilayer boards that go through standard production lines every week 鈥� consumer products, industrial controls, mid-range networking gear 鈥� you want a material that processes cleanly, measures consistently, and is backed by detailed, credible datasheets. The Panasonic R-1766 glass epoxy PCB material checks all of those boxes. Know its Tg limits, don’t push it into high-speed signal applications it wasn’t designed for, and it will serve your design reliably.