Panasonic R-5735 MEGTRON M: Route Length and Stackup

Establish the exact material pair

Panasonic identifies R-5735 laminate with R-5630 prepreg. The regional material page distinguishes several thermal measurements and lists electrical values with their frequencies. Those are specimen characterization data, not a complete line model for every pressed construction.

Record glass style, resin content and the proposed dielectric separation for each relevant signal layer. A core and a pressed bonding interval can have different design inputs even when they belong to the same material family.

Construction decisions at a glance

Turn the loss budget into a conditional route length

Subtract fixed discontinuity losses and reserved margin from the allowed channel loss. Divide the remainder by a complete routing-loss rate measured or modeled for the proposed geometry. Keep all terms at the same frequency and reference planes.

The example uses 20 dB allowed, 5 dB fixed and 3 dB reserved, leaving 12 dB for routing. At an assumed 1 dB per inch, that corresponds to twelve inches. This is not an R-5735 reach specification and does not check reflections or crosstalk.

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.

Compare with the correct neighboring task

The MEGTRON 4S page addresses thermal history and reliability for another mid-loss construction. Compare exact material data and finished geometries rather than assuming similar application descriptions mean electrical or process equivalence.

For a broader selection, the MEGTRON series comparison considers complete channel benefit alongside commercial scope. It is appropriate when the route-length calculation exposes a real need to change the material class.

Avoid letting a thickness change hide in the model

Changing dielectric thickness alters the line geometry required for controlled impedance. That can change conductor loss and routing density. Recalculate the complete line model when the fabricator proposes a different core or prepreg construction.

Retain copper profile and final trace dimensions with the result. A Df-only estimate cannot establish how much length a real route can support, particularly where roughness, vias and launches contribute materially to the total loss.

Review hybrid structure as a manufacturing decision

A hybrid build can reserve the relevant material for selected layers, but the bonding sequence and dimensional behavior need review. Identify resin boundaries and which return planes support the sensitive channels. Do not approve a mixture from a spreadsheet of isolated properties.

The HIPER V hybrid guide discusses structural standard-loss layers as a separate task. Its use requires a reviewed stackup; it is not a blanket alternative for every layer next to an R-5735 signal.

Bring a bounded question to quotation

Send the longest route, allowed loss, frequency, copper, proposed dielectric intervals, layer count and board dimensions. Identify which requirements are fixed and which construction details remain open. Include quantity and the requested electrical evidence.

Enter only your own allowances in the cost comparison. Keep coupons, testing and qualification effort within the same scope for both options. A useful response explains the manufacturable proposal and its exceptions; the worksheet cannot authenticate material supply or replace first-article verification.

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.