PCB Fiducials: Plan Alignment Before Assembly

Fiducials are reference features used by assembly equipment to locate the board. Treat them as part of the manufacturing interface rather than decorative dots added at the end of layout. Their usefulness depends on where they are, whether the equipment can see them and how the panel will be handled.

Distinguish board and panel references

A reference on a panel rail and a reference on an individual circuit serve different registration needs. Eurocircuits' assembly guidance discusses both panel and individual-board fiducials. The required arrangement should be agreed with your assembler for the actual process; copying another supplier's dimensions does not establish an accepted DIYIPCB setup.

If the fabricator will create the panel, state whether fiducials and tooling features are included in that proposal. Do not assume a panel drawing supplied by one team includes everything another team's equipment expects.

Check visibility after assembly planning

Review the proposed marks against component bodies, connectors, rails and clamping areas. Show the assembly side and identify anything that may obstruct recognition. A mark that is visible in CAD may be covered by a component overhang or inaccessible in the selected handling arrangement.

Avoid using an ordinary signal pad as an undocumented substitute. Provide an explicit reference feature and the clear surrounding area requested by the assembler. Keep solder-mask and legend artwork from creating an unintended appearance around the mark.

Ask for the requirements before layout freeze

• Request the preferred size, shape and clear-area rules.
• Confirm the number and placement required on each assembled side.
• Identify any fine-pitch region needing additional local review.
• Agree panel rails, orientation and tooling features together.
• Check whether the stencil registration method has related requirements.

Keep the manufacturing package synchronized

For example, if panel rails are widened after the stencil has been ordered, the registration arrangement may no longer match. Issue the updated panel drawing to fabrication, assembly and stencil preparation at the same time. Label the approved revision and remove superseded files from the active release.

Before approving the build, inspect the full panel view with the populated-component outlines enabled. Confirm that the assembler can identify the reference features without guessing. Preserve that approved setup for repeat orders and revisit it when board shape, component placement or panel orientation changes.

Technical reference: Eurocircuits: assembly fiducials. Supplier-specific process limits in the reference are not DIYIPCB manufacturing commitments.