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Identify the R-5775 designation before selecting a value

Panasonic MEGTRON 6 is a material family, while an R-5775 designation identifies a laminate product within that family. The suffix is part of the specification. A design note that only says MEGTRON 6 can leave important construction details unresolved, especially when the electrical model, approved stackup and purchasing description were prepared by different people.

Panasonic's published family information distinguishes R-5775(N) using low-Dk glass from R-5775(K) and R-5775(G) using normal glass. The corresponding prepreg designations are in the R-5670 family. These names describe different product roles and variants; they should not be treated as interchangeable text labels. Confirm the exact current designation, construction and source document with the fabricator before releasing the material requirement.

This page focuses on reading an R-5775 data record and carrying its conditions into an engineering request. For a broader manufacturing discussion, use the MEGTRON 6 PCB page. For the manufacturer-wide material context, see Panasonic PCB materials. The worksheet below records a selected value and its conditions. It does not select a production stackup, guarantee stock or replace a field solver and the fabricator's approved construction.

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Read a property together with its test conditions

A dielectric constant without a frequency, method and specimen description is an incomplete engineering record. The value may be useful for identifying a material family, but it should not automatically become the design Dk used for an impedance or loss model. Different measurements and constructions can answer different questions. Preserve the information needed to understand which question a particular number answers.

For a dated example, Panasonic's January 2024 circuit-board-materials catalogue lists typical R-5775(N) and R-5775(K)/(G) properties on the MEGTRON 6 page. At 13 GHz, the table gives Dk values of 3.34 and 3.62 respectively, using a balanced-type circular disk resonator method with C-24/23/50 conditioning and a stated 0.75 mm sample. These are source-specific typical values, not guaranteed production values or universal impedance-design inputs.

Record the document date and exact table or row beside the value. If a later source uses another frequency or specimen, do not silently overwrite one number with the other. Ask which data the fabricator uses for the proposed construction and why. This habit is particularly useful when a schematic note, simulation project and purchase specification have been maintained independently and may contain different generations of the material data.

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Separate laminate, prepreg and the finished dielectric

A laminate core and a prepreg layer have different roles in a multilayer construction. The core provides a defined cured material and copper structure, while prepreg participates in bonding and becomes part of the finished dielectric after processing. A nominal material-family match does not, by itself, define the pressed separation between conductors in the completed board.

Specify the core construction, prepreg selection, copper distribution and intended finished stackup with the fabricator. Resin content, glass style, ply count and processing conditions influence how a proposed construction is implemented. The fabricator needs to review the combination rather than simply accept a total board thickness and infer every internal spacing. A finished thickness requirement also has tolerances that should be distinguished from the nominal values in an early design drawing.

When the board uses a hybrid construction, identify which signal layers depend on the low-loss material and which layers serve other purposes. Do not copy one Dk value into every dielectric region merely because one part of the stackup contains R-5775. The PCB material guide can help organize the selection discussion. The final release should retain an agreed layer-by-layer construction and a clear process for approving any material change.

Connect the material record to impedance and loss design

Controlled impedance depends on geometry as well as dielectric properties. Trace width, conductor thickness, reference-plane spacing and the actual cross-section all matter. A material designation alone cannot determine a manufacturable trace width. The PCB impedance guide explains the wider relationship between preliminary calculations and a fabrication stackup that must be confirmed for the project.

Transmission loss also includes more than the laminate's dissipation factor. Conductor characteristics, copper roughness, routing geometry, transitions, connectors and the measurement arrangement can affect the result. A material comparison should keep those conditions coherent. A generic percentage improvement copied from a different transmission-line structure does not establish the improvement in your channel.

Use the data-record worksheet to preserve the selected laminate suffix, Dk, frequency, method and specimen description. Its output is a review note, not an impedance calculation. If the value is a typical datasheet value, the result explicitly asks for a fabricator-agreed design basis. If you already have an agreed design value, record the associated stackup document and revision. This makes the next engineering conversation more precise without pretending that a browser worksheet can validate the entire high-speed channel.

Do not use Tg as a continuous operating rating

Glass-transition measurements describe a material response under a specified method; they are not a universal maximum operating temperature for the finished electronic assembly. A Tg value should remain associated with its measurement method. Differences between DSC and DMA values are not a reason to choose whichever number is larger and use it as a service-temperature limit.

Thermal design and reliability review also involve expansion, thermal exposure, moisture, the via structure, the lamination sequence and the assembly process. A demanding reflow or rework profile cannot be approved solely by checking that a catalogue Tg appears higher than a selected temperature. Likewise, a material-family thermal property does not establish that every board construction using that family has passed a particular reliability test.

State the assembly and service conditions that the project requires, then ask for the relevant material and construction evidence. The high Tg PCB guide provides a separate explanation of thermal-property terms and test methods. Keep that thermal discussion connected to the actual stackup rather than treating high-speed electrical performance and thermal reliability as interchangeable reasons to select a laminate.

Specify the construction before estimating its cost

For an R-5775 project, useful cost questions concern the exact grade, available core and prepreg constructions, copper requirements, layer arrangement, quantity and manufacturing operations. Board area alone cannot establish a reliable quotation. A proposed stackup may also require discussion of panel utilization, material procurement and any special via or sequential-lamination requirements.

Do not use a generic FR-4 multiplier as if it were a current R-5775 market price. If you have supplier-provided allowances, identify their date, quantity basis and scope. A planning calculation can organize those inputs, but it cannot confirm stock or replace a reviewed quotation. For a family-level planning worksheet, use the MEGTRON 6 engineering and budget tools and retain their stated assumptions.

For a formal request, send the released fabrication data and the agreed or proposed stackup, identify the exact material designation and state any permitted alternatives. If substitutions are prohibited, make that explicit. If alternatives are open for discussion, describe the electrical and thermal requirements that must be preserved. The PCB manufacturing service provides the return route to the commercial fabrication discussion without making this model-reference page a duplicate service hub.

A useful engineering handoff example

Suppose a designer has selected a published Dk value for a preliminary stripline model but the purchasing note only says MEGTRON 6. Before requesting manufacture, the engineer should identify the exact source row, laminate suffix and model frequency. The fabricator then reviews a proposed construction and supplies or agrees the relevant design basis. The result is an explicit stackup record, not merely a matching brand name on two documents.

If the selected catalogue row concerns one specimen while the proposed core uses another construction, that difference should be visible in the review. It may lead to a revised model or a different material choice, but it should not be hidden by rounding the numbers until they look similar. The goal is traceable assumptions: a later engineer should be able to understand why a particular Dk was used and which construction it represented.

The worksheet can record that context and produce a downloadable note. It cannot detect whether the entered source description is accurate. Do not type a placeholder and treat the resulting record as evidence. Keep the original document reference, the fabricator's response and any agreed stackup revision with the design release. This is particularly valuable when the board moves from prototype validation to repeat production or to another approved manufacturing arrangement.

Questions to settle before a material quotation

Is R-5775 the same as R-5670? No: the published family designations distinguish laminate from prepreg. Is every MEGTRON 6 variant interchangeable? No; identify the suffix and construction and obtain the appropriate engineering approval. Can the catalogue Dk be used directly in a model? It may be an initial reference, but the design basis must be appropriate to the construction, frequency and modeling method.

Does a material datasheet establish 吃瓜tv's current stock or a guaranteed lead time? No. Those are project-specific commercial questions. Does this page reproduce the complete Panasonic specification? No. It gives a dated example and a method for reading the current official documents. The original source and the agreed fabrication specification remain the appropriate references for release decisions.

To obtain a useful response, contact 吃瓜tv with the exact material designation, board revision, layer arrangement, quantity and the unresolved engineering question. Include the source document or stackup reference you are working from. You can request help before the construction is finalized, provided provisional inputs are clearly marked. That turns a broad request for MEGTRON 6 into a technical conversation about the board that actually needs to be manufactured.