What are fiducial marks or non-fading marks on a printed circuit board?
Editorial Team - PCB Directory
Jan 15, 2020
Fiducial marks are recognition marks, created in the form of small pads on the PCB board to act as reference points for PCB Stencil alignment and for automated component placement by Pick and Place machines. During the PCB Assembly process these points are used by automated machines to ensure correct positioning of the board. These points are also measurable and act as a frame of reference during SMT component placement.
When an operator loads the PCB board for printing or component placement, the machine identifies the fiducial marks on the PCB and uses image recognition to match the exact location. This way, the automatic machine aligns itself based on the fiducial marks.
The addition of fiducial marks is a part of PCB circuit artwork. It means that the PCB circuit pattern and fiducial marks should be etched at the same step. The desired base material of the fiducial mark should be copper protected by an anti-oxidation coating. The fiducial locations are added to the stencil and pick & drop data file.
It is always recommended to create three fiducial marks on the PCB since it helps the automated machine to identify whether the board is loaded in the right direction or not. Two fiducial marks are also acceptable.
Types of Fiducial marks:
There are two types of fiducial marks available based on their location on the PCB board:
Key Guidelines for creating fiducial marks on a PCB:
While adding the fiducial marks, the following points should be considered:
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