fiducial marks

Fiducial marks is the reference features on PCBs or panels used by assembly equipment to establish accurate coordinate registration - they anchor machine alignment and compensate for real-world board variation.

What Is Fiducial marks?

• Definition: Fiducials are high-contrast geometric marks recognized by placement and inspection vision systems.
• Types: Global fiducials align the board, while local fiducials improve region-specific placement accuracy.
• Placement Rules: Location, clearance, and solder-mask design affect detection reliability.
• Process Usage: Used by printers, pick-and-place machines, and AOI platforms.

Why Fiducial marks Matters

• Registration Accuracy: Reliable fiducials are essential for precise print and placement alignment.
• Yield: Poor fiducial design can produce systematic offsets and broad lot failures.
• Fine-Pitch Support: Dense designs require strong local registration to avoid bridge defects.
• Changeover Stability: Consistent fiducial strategy reduces setup errors across products.
• Automation Reliability: Good fiducials reduce vision false detections and cycle interruptions.

How It Is Used in Practice

• Design Standard: Use uniform fiducial shape, copper finish, and keep-out across product families.
• Panelization: Place fiducials to support both panel-level and unit-level machine alignment.
• DFM Review: Audit fiducial visibility and solder-mask clearance before PCB release.

Fiducial marks is a foundational reference system for high-accuracy electronics assembly - fiducial marks should be treated as critical process features, not optional board artwork details.