Define what repeat means

Freeze the accepted stack, via architecture, material policy, artwork revision, finish, impedance requirements, and inspection plan. Identify which characteristics require design-owner approval before changing. This is especially important when a supplier proposes an apparently equivalent material or a different route through the fabrication process.

Keep manufacturing questions and their resolutions with the released package. A note accepted in an email during the prototype should not disappear when purchasing places the repeat order using only a board part number.

Make acceptance executable

State the applicable specification and revision, product class where relevant, sampling agreement, and records to provide. Distinguish the test method from its pass/fail requirement: a method explains how a measurement is made, while the purchase agreement and applicable specification establish what is acceptable.

IPC's document revision table is useful for checking document identity. Do not use a remembered revision or an informal claim of 'IPC compliance' as a substitute for the requirements actually agreed for this product.

Watch changes that can hide in a repeat order

Imagine a controller that has passed qualification on one stack. A later order changes dielectric construction to fit available inventory. Unchanged finished thickness is not proof that the electrical and mechanical behavior remains equivalent. Review the affected requirements and the evidence needed before accepting that change.

  • Identify material and stack revisions on order records.
  • Retain lot identity for received boards and assembled units.
  • Review deviations and rework dispositions before release.
  • Use failure feedback to update the risk-based inspection plan.

Transfer knowledge between teams

The design, purchasing, quality, and assembly teams need the same baseline. Provide a compact production handoff listing critical features, accepted substitutions, required reports, handling requirements, and escalation contacts. This prevents the highest-risk assumptions from being understood only by the engineer who managed the prototype.

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 a certificate of conformity replace test records?

It serves a different purpose. Define which supporting measurements or reports the product requires and how they are associated with the delivered lot.

Must every material substitution trigger full qualification?

Not necessarily. Use a documented impact assessment to determine the scope of review and verification appropriate to the actual change.

References & further reading

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