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Read the chart with its construction basis

The current ITEQ introduction lists Dk 3.7 and Df 0.0070 for IT-958G on the chart's 50% resin-content basis. Retain the corresponding technical document and frequency/method conditions. A headline pair is not a universal value for every core and prepreg construction.

The IT-170GRA2 guide owns a different material comparison. If both are candidates, request their proposed glass, resin and copper constructions rather than ranking them only by a single catalog number.

Material facts and decision boundaries

Explain what dielectric loss leaves out

The worksheet uses a small-loss homogeneous TEM approximation from entered frequency, Dk, Df and path length. It estimates dielectric attenuation only. Conductor resistance, surface roughness, plating effects, vias and connectors are not included.

That boundary matters when a designer compares the result with a measured trace. A large difference does not necessarily invalidate the dielectric data; the measurement may include additional mechanisms and different reference planes. Keep the model and measurement boundaries explicit.

Homogeneous TEM dielectric loss illustration

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 吃瓜tv quotation. You can contact the team without completing it.

Choose input data for the actual layer

Record glass style, resin content, dielectric separation, copper profile and the intended trace geometry. A material can produce different effective electrical behavior in different constructions. Do not use a process-control characterization value as a validated design Dk without checking its intended use.

If the required frequency lies outside the available data, identify that extrapolation as an assumption. A calculator can accept a number without validating it. Preserve the source and uncertainty rather than letting a precise-looking output imply more knowledge than the input supports.

Compare copper and dielectric improvements together

A lower-loss dielectric may reveal copper roughness as a larger part of the remaining attenuation. Changing copper can also affect adhesion, processing and available constructions. Review those tradeoffs with the fabricator and keep the exact proposed foil in the stackup.

For a lower-loss glass-system discussion, IT-988GSE provides a distinct page. Its historical identity must not be confused with current IT-988GLSE. A material-family upgrade is not a guaranteed interface improvement without a compatible full-channel analysis.

Protect legacy electrical requirements during substitution

An older IT-200LK design may contain delay or phase requirements that are not captured by a Df comparison. Recover the original model and decide which dimensions may change before proposing IT-958G as an alternative.

Keep impedance, attenuation and phase as separate review items. A geometry adjustment can recover one target while changing another. Agree how representative test structures or measurements will support the proposed construction.

Prepare a useful low-loss RFQ

Provide the IT-958G designation, operating band, critical routing, copper, layer structure, board dimensions and quantity. Identify the electrical source data and required testing. State any restrictions on material or foil substitutions.

The optional cost worksheet has no material-price feed. Use comparable quoted allowances and include any one-time electrical verification. The output can be attached manually, but it cannot approve the channel or promise stock. The final proposal needs the actual construction and acceptance boundary.

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.