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While making PCB, I added 8 fiducials (fids) marks so that pick and place machines use these marks as referent points on the PCB to position the surface mount components (Packages) during assembly.

But when I sent same Gerber file to stencil manufacturer, they asked me "do you require fiducials half etched or through cut".

I don't have any idea about half-etched fids. Could someone explain the difference between these two?

All I can found a web link but it does not serve the purpose.

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  • \$\begingroup\$ I've been in PCB design/manufacturing and have no idea what you are talking about. Please explain or add photo's. \$\endgroup\$
    – user125002
    Commented Apr 25, 2017 at 8:48
  • \$\begingroup\$ @JWRM22 I just send my Gerber file for the making stencil & they asked me "Do you require fiducials half etched or through cut?". After searching online what I know till know is the half-etched fiducial is us for the stencil projects, not for PCB it's actually "half-lasered" in recent stencil technology and the usual way to apply fiducials and text on solder mask stencils but a fiducial is an etched mark or drilled hole used for optical positioning during assembly processes. \$\endgroup\$
    – Kapil Singh Rawat
    Commented Apr 25, 2017 at 9:18
  • \$\begingroup\$ If this is a paste mask, I would guess that you would not want through-cut for the fiducials as you don't want solder there. I have been a little unclear on this as well and leave the fiducials on the gerbers for the paste masks with an off-board text note that the fiducials are for position reference only. I hope someone understands the problem and provides a decent answer. \$\endgroup\$
    – Tut
    Commented Apr 25, 2017 at 10:14
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    \$\begingroup\$ I am not familiar with half-etched fiducials, but would guess that this would allow a two-step process of aligning the board fiducials, followed by aligning the stencil half-etched fiducials to the same positions. If you use an EMS (electronics manufacturing service), you should ask them although our EMS handles ordering the stencils (and therefore deals with this issue). \$\endgroup\$
    – Tut
    Commented Apr 25, 2017 at 10:22

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According to Seeed Studio, there are three options for fiducials on SMT stencils. Note what they say about half etched fiducials below:

No fiducial ---- No positioning holes required on the stencil

Etched Though --- Positioning holes that go all the way through the stencil. Useful for manually holding the stencil in a fixture for manual/semi-manual paste application. These should be specified in the files by the customer since exact requirements depend on the customers' own preferences.

Half Etched --- Holes that go half-way through the stencil. These are needed for some fully automated paste applicators. The diameter is typically 1mm and are added to the corners of the stencil by our engineers if not already designed in the files.

SOURCE: http://support.seeedstudio.com/knowledgebase/articles/1156336-what-are-smt-stencil-fiducial-marks

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