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MEGTRON 6 is a series, not one universal stackup

MEGTRON 6 PCB fabrication starts with the exact material designation and construction. 鈥淢EGTRON6, low loss鈥� leaves open the glass type, laminate and prepreg pairing, copper surface and electrical data used for design. These choices influence the channel model and the procurement request. Use the series name to identify the family, then specify what will actually be laminated into your board.

This page concentrates on the MEGTRON6 variants and their use in a project. The broader MEGTRON PCB family guide handles discovery across families; Panasonic PCB materials also covers non-MEGTRON construction routes. Keeping these decisions separate makes it easier to locate the right evidence without comparing an entire catalogue every time a drawing changes.

A board intended for a fast interface needs an agreed channel budget and verification plan. Material selection is one part of that work. Do not infer a supported data rate, maximum trace length or acceptable eye opening from a Df headline alone. Geometry, transitions, connectors and operating conditions must remain part of the review.

Read the suffix and test conditions together

identifies R-5775(N)/R-5670(N) with low-Dk glass, and K/G variants with normal glass. It separately lists R/S variants using buried-resistor copper foil. Those designations should remain visible in the material record; do not silently transfer ordinary laminate values to a resistor-foil construction.

The supplier describes these as typical, not guaranteed values, for a 0.75 mm specimen; the associated foil reference is H-VLP. This is a compact identification table, not the full procurement specification. Preserve the underlying document when comparing another grade or thickness.

The , dated April 2022, provides thickness, cloth and resin-content entries rather than one Dk for every construction. That is the level of information a stackup review needs. For example, changing core thickness can also change the reinforcement and resin fraction. Ask which row or qualified design model supports the proposed structure.

A useful first calculation: dielectric-only loss

For a uniform, nonmagnetic, low-loss TEM transmission line, dielectric attenuation can be approximated as loss in dB = 8.686 脳 蟺 脳 f 脳 鈭毼祌 脳 tan未 脳 L / c, with frequency in hertz and length in metres. It is useful for checking scale and sensitivity. It is not a complete simulation of a routed PCB channel.

Take a synthetic example at 10 GHz, relative permittivity 3.5, loss tangent 0.004 and length 100 mm. The dielectric-only contribution is approximately 0.68 dB. Doubling length doubles that contribution in this model. If the board allocation is 3 dB, the remaining arithmetic allowance must still cover conductor and transition effects that have not been counted elsewhere. It is not a measured 2.32 dB system margin.

The formula assumes the field is filled by one uniform dielectric. Microstrip has field in more than one medium, so applying bulk Dk and Df directly would overstate what the model knows. Mixed dielectrics, dispersion and anisotropy also need more careful treatment. The worksheet withholds its simple result for a microstrip or mixed-material selection and directs the task to a geometry-aware model.

Explore frequency, loss tangent and routed length

Enter values applicable at the chosen frequency and record their source. The example is intentionally synthetic: it does not claim to be a guaranteed MEGTRON6 construction. A numerical result does not authenticate the data entered. If Df was measured under a different method or condition, resolve that difference before treating candidates as comparable.

Use the output to ask better questions: is dielectric loss likely to consume most of the allocation; does reducing length materially change the choice; which omitted loss contributor needs evidence next? Do not multiply the dielectric-only result by an arbitrary safety factor and call it total insertion loss. A channel model and suitable verification must address the actual stackup and transitions.

Keep the copper surface in the channel model

The conductor is not electrically smooth just because the dielectric has a low loss tangent. Foil type, treatment face, roughness metric and finished conductor geometry affect the model. Identify which copper interface is represented by a roughness measurement. Values labeled Ra, Rq and Rz cannot be substituted for each other without a supported conversion and measurement context.

The RF copper foil roughness guide separates skin-depth scale from a validated loss model. Use it when the next decision concerns foil rather than laminate family. Copper procurement, bond requirements and circuit loss should be reviewed together; selecting the smallest number in a roughness table does not by itself qualify the full construction.

For external layers, include the relevant surface finish and solder-mask conditions in the electrical model. For inner layers, confirm the bonding interface and treatment assumptions. Ask the fabricator whether the proposed foil and core combination can actually be purchased and processed for the build quantity. An attractive catalogue combination is not useful if it is not the one that will be built.

Translate the chosen grade into routing geometry

Provide the signal and reference-plane assignment before fixing trace dimensions. State target impedance, the layer carrying each controlled structure, copper convention and whether the dielectric spacing may be adjusted. Different constructions within a material family can require different dimensions to obtain the same impedance. The approved output should be a finished stackup tied to the design revision.

Review holes and layer transitions at the same time. A low-loss horizontal route can still have an unfavorable vertical transition. Identify via spans, unused barrel length, return paths and any back-drill requirement. Keep those features in the loss and reliability discussions rather than treating them as late manufacturing notes. The PCB impedance page provides a more detailed geometry-oriented starting point.

Mixed constructions need an explicit compatibility review. Do not assume that assigning MEGTRON6 to selected high-speed layers and another material elsewhere is automatically process-compatible or electrically homogeneous. Document the local dielectric environment of each critical net and the lamination sequence proposed by the fabricator. Cost optimization should follow the qualified construction, not precede it.

Tg, assembly exposure and declarations answer different questions

Tg identifies a transition measured by a specified method. It does not mean continuous service at that temperature, nor does it directly state how many reflow cycles an arbitrary board can tolerate. A time-to-delamination test and a product assembly profile also have different specimens and acceptance questions. Record the planned thermal history and the evidence needed for the actual board thickness and via structure.

MEGTRON6 branding also spans distinct product developments. If halogen content matters, name the exact grade and require the applicable declaration. Do not copy a statement for a halogen-free product onto a conventional R-5775 order because both descriptions contain 鈥淢EGTRON6.鈥� The halogen-free material evidence guide helps separate composition statements from broader product obligations.

Budget the build and the evidence

MEGTRON6 project cost depends on the grade and foil combination, core availability, minimum purchasing quantity, panel utilization, number of process steps and verification scope. A prototype with a demanding coupon plan may carry a different cost structure from a repeat board using already approved construction. Ask which allowances are one-time and which vary with delivered quantity.

Use your quoted or internal amounts in this planning worksheet. The material field is incremental to the fabrication allowance; set it to zero if that cost is already included. Record whether electrical coupons, measurement, documentation and nonrecurring engineering are covered. The calculator is uncalibrated and does not turn the loss model into a price. Engineering changes must prompt a separate budget review.

Make verification part of the enquiry

Send the fabrication files, stackup, complete material callout, quantity and controlled-impedance table. For channel-loss requirements, also state frequency range, reference planes, test structure, de-embedding expectations and acceptance limits. If the requirements are still under development, identify the engineering decision you want the response to support. A supplier cannot infer the correct electrical acceptance from 鈥渉igh speed鈥� alone.

Keep the approved coupon and board constructions connected. A result obtained on a different dielectric thickness or foil surface may not represent the production route you intended to validate. Document any permitted material substitution and its revalidation trigger. Archive the final source revision, proposed stackup and agreed exceptions with the manufacturing release so a later repeat order has a clear baseline.

For a request already anchored to an exact conventional designation, the existing R-5775 reference page remains a related grade lookup. Reconcile any historical data there against the current supplier document before release. This series page does not create a second grade identifier or automatically replace that URL.

Common MEGTRON 6 decisions