For each controlled structure, state the target value and tolerance, single-ended or differential type, signal layer, reference layer or layers, nominal trace width and spacing, copper requirement, material or dielectric assumptions, and coupon or measurement requirements.
Build an impedance table
Use a unique identifier for each structure and apply the same identifier in the layout notes, stack-up, and drawing.
- Target impedance and permitted tolerance
- Single-ended, differential, coplanar, or other structure
- Signal and reference layers
- Nominal line width and differential spacing
- Copper and dielectric assumptions
- Coupon quantity, location, measurement, and report needs
Geometry adjustments need agreement
Manufacturing compensation or a proposed stack-up may require geometry changes. Define whether adjustment is permitted and who can approve it. Testing is not assumed for every order; it should be included in the agreed quotation and fabrication requirements.
Next useful step
Final capability, commercial terms, and project records are confirmed against the actual RFQ and written project documents.