Understanding Fiducial Markers on PCBs

January 14, 2021

By Zack Keas

With a better understanding of What is Needed to Quote Your Circuit Board Assembly, I would now like to discuss Fiducial Markers and the advantages they offer to yield the best possible placement of SMT components.

When your custom PCB is fed into our SMT Pick and Place machines for SMT component placement, the first process our SMT Pick and Place machines look for are the three (3) fiducial markers to recognize the X and Y position of the PCB.  Why is that important, because with a known X and Y position baseline, the SMT Pick and Place machines can optimally place the SMT components.

Now that you know more about the importance of fiducial markers, here are recommendations on how to incorporate them into your custom PCB design.

The fiducial marker is made by placing a non-drilled copper layer in a circular shape.  The fiducial marker must be free from solder mask.

The optimum size of a fiducial marker should be between 1.5mm and 3mm. A clearance area similar to the diameter of the marker must be maintained.

The fiducial marker must maintain a distance of 0.3 inches to the edge of the board, excluding the clearance area of the fiducial marker.

While having fiducial markers on the PCB is ideal, if your board is already in production, or if due to regulatory requirements, adding fiducial markers is not possible, SMD can add these fiducial markers to the breakaway PCB border, aka PCB rails.

SMD is happy to answer any questions you have.  Contact US today and we look forward to hearing from you.