Fiducials

[Dan]

Professor Tom

I heard that every SMT part on my board needs a fiducial!
What is a fiducial and is it necessary for the them to be near each part? Or is one per part anywhere on the board OK?
Thanks for all your help.

Dan

[Tom]

Dan,

Fiducials are a PCB artwork feature that is created in the same process as the conductive pattern and provides a common measurable point for component mounting with resept to a land pattern. Only parts that have a lead pitch of less than 0.625mm require a "Local Fiducial".

If the lead pitch is greater than 0.625mm, then the part does not require a fiducial.

FIDUCIAL SIZE
1mm round etch pad with a 2mm min. solder mask clearance. Used as a bomb-site target for automated assembly equipment alignment tools.

GLOBAL FIDUCIAL LOCATION
Are placed in three corners, generally next to the tooling holes, of a printed circuit board. They are used for assembly equipment alignment tools.

LOCAL FIDUCIAL LOCATION
Are placed in 2 corners of fine pitch quad flat packages or BGA's. They are used for assembly equipment alignment purposes.

[Dan]

Thanks Tom,

Can I build these local fiducials right into my fine pitch components?

Also is there a quick metric to inch converter on this web site?

Thanks again,

Dan

P.S. I've just been on the Innoveda web site. I see that they also have a forum for PowerPCB users. I'll have to check that out. I also see there is going to be a Users Conference...... and you'll be a class instructor. My guess is that seeing as I'm so new to this SMT stuff, I should probably try and get out there and take your class?

Are you a traveling teacher, or just local to the San Diego area?

[Tom]

Dan,

Yes, build the fiducials into your library parts.

Here is the URL to download the Inch to Metric Converter: http://www.pcbstandards.org/downloads/Metric%20Environment/Programs/Convert/

I did not know that Innoveda started a Forum. I think you are referring to the PowerPCB listserver - http://ug.innoveda.com/listserver.htm

I am a professional conference speaker and I will be speaking at the International User Group in April. I'm speaking at our Local User Group (I'm the Chairman) next week on "Defining a CAD Library". We have 90 RSVP's for the one day event.

I do not travel for training any more, but you might want to contact Patrick Colcernian - Patrickman@dls.net . Patrick is one of the best PowerPCB teachers in this country and we co-author many technical papers and articles.