Shengyi Synamic 8G PCB: High-Speed Material and Loss Budget

Start with exact identity and source method

The cited official 8G product page presents headline Dk/Df of 3.66/0.0032 at 10 GHz and Tg of 200°C by DMA. Obtain the controlled technical sheet and construction-specific method context before carrying those values into a released design model.

A DMA Tg must not be compared as though it were the same measurement as a DSC value. Likewise, a headline loss tangent is not complete insertion loss. Preserve the supplier revision, glass/resin construction and copper choice rather than assuming every 8G stackup has the same electrical behavior.

Source-qualified material review

Allocate the losses that do not scale with route length

Connectors, vias, packages and other transitions consume part of a channel budget. Their treatment depends on where the reference planes are placed. A planning model should not count a package twice or omit a connector merely because it appears outside the PCB outline.

Reserve any engineering margin explicitly. Do not hide it inside an unexplained routing-loss rate. This makes it possible to see whether a design problem is driven by the route, a transition or the chosen uncertainty allowance.

Calculate the remaining uniform routing length

The worksheet subtracts fixed losses and margin from the allowed total, then divides the remainder by the entered complete routing attenuation. With 20 dB total, 5 dB fixed, 3 dB margin and 1 dB/in, the arithmetic length limit is 12 inches. This is a hypothetical example, not an 8G material rating.

If the remaining allocation is negative, changing route length cannot solve that particular budget. Revisit the fixed allocation, interface assumptions or architecture. A zero routing-loss input is rejected because it would produce an undefined or misleading length result.

Keep a route budget separate from channel qualification

The scalar calculation is an early planning aid. Real channels have frequency-dependent insertion and return loss, crosstalk and signal-processing assumptions. A route shorter than the calculated limit can still fail another requirement.

Use simulation and appropriate measurements for the released construction. Keep the source of the complete attenuation rate visible: measured coupon, validated model or a labeled preliminary assumption. A Df number alone does not supply that rate.

Compare neighboring materials without losing construction control

The Synamic 6N guide explains method-dependent material data, and the 6GX channel worksheet evaluates a budget at a specified route length. These are useful adjacent tasks, but neither authorizes replacing 8G without a reviewed comparison.

If an RF laminate such as the one discussed in the S7136 process guide is proposed, reassess electrical and manufacturing compatibility. Keep foil, dielectric thickness, thermal exposures and qualification requirements in the comparison instead of ranking materials by a single loss-class label.

Routing length from remaining loss allocation

Optional cost comparison from your own allowances

Use a quotation or a clearly labeled internal assumption for each input. Keep the quantity, construction and inspection scope the same when comparing alternatives. This uncalibrated planning model adds entered values; it contains no current market rates and does not issue a RAYPCB quotation. You can contact the team without completing it.

Build the RFQ around the limiting requirement

Send the exact 8G callout, proposed stackup, routing constraints, impedance targets, relevant frequency range, quantity and board dimensions. State whether the material is mandatory or an alternative can be assessed. Include the requested evidence and the approval owner for changes.

The cost worksheet uses only the allowances supplied by the visitor. Compare the same quantity, test scope and construction when evaluating proposals. The final manufacturing response should identify open electrical assumptions and the proposed verification route, rather than promising a data rate from the material name.

Tie the exact grade to an electrical construction

State the channel reference planes, frequency range, routing length, copper construction, transitions and interface assumptions together. A laminate loss-tangent value is one input to that system. It is not a complete insertion-loss measurement or a guarantee that a data rate will work.

Use comparable measurement or modeling conditions when screening alternatives. Material changes can require geometry changes to preserve impedance, and copper roughness can alter the result independently of the resin system. Keep the proposed stackup and the channel analysis synchronized through fabrication review.

For procurement, identify the properties that are fixed and the alternatives that can be evaluated. Request evidence at the relevant construction and frequency rather than a broad low-loss label. Compare total delivered scope and validation effort alongside material price. A shorter or better-routed channel may change the tradeoff more than replacing a material name alone.

A useful design-data record retains both the material value and the reason it was selected. State whether the value is supplier characterization, a construction-specific design input, a measured coupon extraction or an early assumption. These sources are not interchangeable. Keep frequency, method and specimen information visible when a comparison uses more than one document.

The tool on this page starts empty because a plausible default can otherwise be mistaken for a verified grade profile. Use the example to understand the units, then replace it with project inputs. A result with many decimal places does not imply that the material or routing-loss input is known to that precision.

For a high-speed design, plan how the model will be checked. Reference planes, coupon geometry, fixtures and the acceptance boundary determine what a measurement means. A coupon that characterizes one line construction does not automatically qualify every route or transition on the board.

Keep the commercial comparison aligned with the engineering one. Quantity, copper, layer structure, test deliverables and qualification effort should be comparable. A lower material allowance can be irrelevant if the proposed construction cannot meet the channel requirement, while a premium grade may be unnecessary if the actual route already has sufficient validated margin.