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.