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The introduction about Fiducial Mark on PCB

2019-05-14


People all know that when we get the PCB boards from the PCB factory, we need to mount the components. Nowadays the components are mounted by assembly machine (SMT). The Fiducial Mark point will be used in SMT process.

What is the Fiducial Marks?

The Fiducial Mark, also called the reference point, provides a reference point for the placement of all components in the placement process. Therefore, Fiducial Mark points are critical to SMT production.

The classification and function of Fiducial Mark.

Individual board MARK, which needs to be used when mounting an individual PCB, it’s on the PCB board;

Panel board MARK, need to be used when mounting a panel of PCBs, generally it’s on break-away of panel;

Partial area MARK, used to improve the accuracy of mounting certain components, such as QFP, BGA and other packages;

The design specification of Fiducial Mark

All SMT boards must have a Fiducial Mark, and the relevant SPEC of the Mark point is as follows:

1. Shape
Mark points are marked as solid circles.

2. Composition
A complete MARK point includes: marker points/feature points and open areas.

3. Location
The Mark points are located relative to each other on the diagonal of the circuit board and are separated as far as possible, preferably at the longest diagonal position. Therefore, MARK points must appear in pairs.

4. Size
The minimum diameter of Mark points is typically 1.0 mm and the maximum diameter is typically 3.0 mm.




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