Choose a complete laminate system that supports the intended loss budget, thermal history and microvia process. A material trade name is only part of the specification.
What to consider
Record the grade, core and prepreg constructions, glass style, resin content and copper foil. Check compatibility across all lamination stages and assembly exposures. If a substitute is proposed, compare electrical properties, expansion, moisture behavior, processing requirements and the factory’s qualification evidence.
A practical review example
Prepare a material comparison using the same route geometry and frequency. Recalculate impedance and channel loss for each candidate rather than swapping a headline Dk into a fixed trace-width table.
Checks before release
- Define loss and thermal requirements before selecting a grade.
- Confirm stocked constructions with the fabricator.
- Document approved substitutes and the required revalidation.
Connect this decision to fabrication
Use the material selector to organize the initial discussion. Keep proposed values separate from the approved drawing and document the effect of any change on the rest of the construction.
- Identify the exact grade, glass style, resin content and copper foil.
- Compare Dk and Df only with their frequency and test method.
- Confirm the material system is qualified for the proposed via structure.
Technical references
FR408HR material and processing resourcesMEGTRON6 material family and test conditionsRO4000 laminate data and processing resourcesReferences checked 2 October 2026. Manufacturer data describes its stated construction and is not an HDIPCB.org manufacturing commitment.