Start with a trustworthy reference

Provide an agreed netlist and final artwork revision. If the electrical reference is generated from the same incorrect fabrication data being checked, the test may confirm that the board matches the mistake. Clarify the intended data comparison and how discrepancies are resolved.

Identify intentional connections, isolated copper, net ties, and features that might confuse automatic extraction. A reviewed exception list is more useful than silently accepting every reported mismatch as a test-system nuisance.

Keep test purposes separate

IPC-9252 is a requirements document for electrical testing of unpopulated printed boards. Its existence does not mean a simple continuity result qualifies impedance or thermal endurance. The purchase specification should identify the applicable scope and requirements rather than relying on the standard number alone.

For controlled impedance, state the structures and targets to verify. For an interconnect stress evaluation, define the representative structure, exposure, measurements, and failure criteria. These may require separate vehicles or records.

Match access to the chosen method

An illustrative dense module has few accessible finished-board pads, yet contains several buried connections. Review test accessibility while the layout can still change. Ask how each required net is contacted or otherwise covered, and how fixtures or test programming are kept aligned with revisions.

  • Identify nets and structures excluded from routine test coverage.
  • Define the required continuity and isolation acceptance levels.
  • Record the board identity and tested revision.
  • Agree how retest, repair, and anomalous results are documented.

Interpret a pass within its limits

A passed test demonstrates compliance with its particular conditions and coverage. It does not establish that an unmeasured characteristic is acceptable. Retain that distinction in incoming inspection and failure analysis: a board can pass one check and still warrant investigation when assembly or service reveals a different problem.

DESIGN NOTE / SCHEMATIC

Adjacent-layer access, one connection at a time

Signal copper

Dielectric · geometry + material

Reference copper

Core or build-up dielectric

Signal copper

Illustrative only. Copper thickness, dielectric construction and via spans require a reviewed stackup.

Common questions

Does continuity testing verify impedance?

No. Connectivity and transmission-line behavior are different measurements. Specify impedance verification when the design requires it.

Are buried vias untestable?

Their connectivity can be covered through accessible endpoints or representative test structures, depending on the design and method. Review actual coverage rather than assuming it.

References & further reading

Method & assumptions · General design guidance. Validate the proposed construction and acceptance criteria for your project.