Define a usable electrical target
State the interface, frequency range, length, impedance requirements, and allowable insertion or return behavior. Specify the reference planes and which transitions the model includes. The electrical design guide separates a geometry target from complete interface validation. A request for ‘high frequency’ alone does not identify a material decision.
Inputs for a low-loss material review
| Decision | Define | Review |
|---|---|---|
| Requirement | Channel limits and operating spectrum | Relevant modeled or measured response |
| Dielectric | Grade and property test context | Consistent simulation assumptions |
| Copper | Foil surface and geometry | Conductor contribution to loss |
| Transitions | Connectors, vias and reference changes | Whole-channel validation |
Keep the property context attached
Compare Dk and Df with method, frequency, conditioning, and construction. Qnity’s AP and LF pages report frequency-specific dielectric values; this is a reason to retain test context, not combine unmatched numbers into a league table. Request data appropriate to the selected grade and model. If a number is typical, do not rewrite it as a guaranteed finished-board acceptance limit.
Evaluate the proposed interconnect
Model the actual copper and reference geometry, then determine which uncertainty justifies a coupon or channel measurement. Compare an LCP alternative only after confirming a reviewable manufacturing construction. Preserve connectors, return-path transitions, and installed routing in the validation scope. Choose the material that resolves the channel requirement with a credible supply and process route.
Before you release the design
- Write the channel budget before selecting a grade.
- Keep every dielectric value's context.
- Include protective and bonding materials.
- State the required verification deliverable.
Watch points
- Low dielectric loss does not guarantee protocol compliance or acceptable connector transitions.
Practical questions
Should the lowest published Df win?
Only if the comparison is relevant and the full channel benefits. Review measurement context, geometry, and the rest of the loss budget.
Does controlled impedance prove low loss?
No. Impedance and loss are related design concerns but require distinct targets and appropriate validation.
Technical references
References support the material or design context. Check the exact grade, part number, document revision and project conditions before release.Updated 27 September 2026 · Technical content policy · Engineering guidance supports project review; the agreed drawing defines the build.