DDR routing requirements depend on the memory generation, controller, topology and package. Use the device-specific design guidance as the source of constraints.
What to consider
HDI can help fine-pitch escape, but it does not remove timing, impedance and power requirements. Establish byte-lane organization and reference planes before routing. Match the relevant timing paths and account for package contributions when the device documentation requires them.
A practical review example
Before adding tuning, verify the permitted topology, termination placement and reference continuity. A layout can have matched trace lengths yet violate the required topology or channel margin.
Checks before release
- Use the actual controller and memory guidance.
- Keep lane and group constraints distinct.
- Validate the channel and power environment together.
Connect this decision to fabrication
Use the signal routing 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.
- Use edge rate and channel loss, not clock frequency alone.
- Keep a continuous return path at traces, vias and connectors.
- Verify final geometry against the device and interface requirements.
Technical references
HDI design and manufacturing overviewReferences checked 2 October 2026. Manufacturer data describes its stated construction and is not an HDIPCB.org manufacturing commitment.