DFM Analysis

Fiducial Analysis will primarily include:

  • Global Fiducial Summary 

Purpose: To ensure a minimal number of global fiducials for proper alignment of the board inside the assembly mac


  •  Local Fiducial Summary

Purpose: To ensure that fine pitch devices have local fiducials placed in the center of the component, or in two opposite corners, to allow fine alignment of the assembly equipment.


  • Non-Uniform Local Fiducial 

Fiducials should be placed equally distant from a component. If this is not the case, it may indicate a design mistake.


  • Fiducial to Copper 

Purpose: To ensure the area adjacent to fiducials is free of exposed copper which may mislead the optical alignment equipment and cause inaccuracies.


  • Fiducial to Hole

Purpose: To ensure the area adjacent to fiducials is free of holes which may mislead the optical alignment equipment and cause inaccuracies.


  • Close Fiducials 

Purpose: To ensure global fiducials are not too close so as to provide the optical alignment equipment sufficient accuracy to account for shift/rotation errors.


  • Far Fiducials 

Purpose: To ensure global fiducials are not too far apart. This is considered bad design practice.


  • Fiducial Close to Rout 

Purpose: To ensure fiducials are a minimal distance from board edge so as to provide a sufficiently contrasted area for the optical alignment equipment.


  • Fiducial to Like Pad 

Purpose: To detect features, similar in size and shape but are not fiducials, which may possibly confuse the optical system in identifying fiducials.


  • Fiducial to Conveyed Edge 

Purpose: To ensure fiducials maintain a minimal distance from the conveyed edge of the board.


  • Fiducial to Non-Conveyed Edge 

Purpose: To ensure fiducials maintain a minimal distance from the non-conveyed edge of the board.


  • Fiducial to Background 

Purpose: To ensure that fiducials are found on a uniform background - either all copper or all laminate - as required by the optical equipment identifying them.


  • Component Covers Fiducial 

Purpose: To ensure that fiducials are not covered by components and are, therefore, accessible to optical inspection systems. This category applies to global fiducials only.


  • Fiducial to SM 

Purpose: To ensure that each fiducial has a large enough gap between it and the surrounding solder mask to provide reliable recognition by optical alignment equipment.


  • Fiducial to SS (Collapse)

Purpose: To detect silk screen features which may confuse the optical fiducial identification system.


  • Component Cen Fiducial (Collapse)

Purpose: To ensure that fine pitch components, requiring a local fiducial at their center, have it. This is in addition to the board global fiducials.


  • Component Local Fiducial (Collapse)

Purpose: To ensure that fine pitch components, requiring two local fiducials placed in their corners, have them. This is in addition to the board global fiducials.


  • Component Global Fiducial 

Purpose: To ensure that each component has at least one global fiducial close to it. A component, far from any fiducial (e.g. more than 4”), may be statistically vulnerable to placement accuracy errors.