I am also adding an annular ring around panel fiducials to protect them during fabrication and
assembly. This is important if the fiducials are a distance away from other copper features
(no venting). I have seen panels with fiducials knocked off during fab or shipping.
Most SMD assembly equipment will have a recommended fiducial in their respective manuals. Some
prefer a diamond, some prefer round. The size is usually in the .040-.060" range with a 2X
clearance around the feature. The association that represents the SMD equipment manufacturers
also has a recommended fiducial.
Watch out for contrasting shades around the fiducial. A trace running to close on an internal
layer may give the optical equipment fits when trying to locate the fiducial.
--
Scott Buscomb, C.I.D.
Techsonic Industries Inc.
PH 770 475-3020 x1032
FX 770 475-4090
[log in to unmask]



Rich Schutz wrote:

> We use  0.060" round fiducials with a 0.140" solder mask clearance located in
> opposite corners of the PCB.  A minimum of 2 fiducials is required. The fiducial
> should be 0.125" from any board edge or panel edge. That distance is  measured
> from the edge of the pad not the center.  Use the 0.140" clearance  ring also
> for distances from all parts, and mounting holes.
>
> Charlene Dwyer <[log in to unmask]> on 01/25/2001 06:01:15 PM
>
> Please respond to "DesignerCouncil E-Mail Forum." <[log in to unmask]>;
>       Please respond to Charlene Dwyer <[log in to unmask]>
>
> To:   [log in to unmask]
> cc:    (bcc: Rich Schutz/perry/apscoinc)
>
> Subject:  [DC] DC IPC Design rules for Fiducial clearances
>
> Hi!  Does anyone know of the standards for board
> fiducials?
>
> The minimum/maximum distance they should be from the
> board edge, panel edge, and the distance they should
> be from a part?  Is there different distances for
> different parts?  Difference for diffent fiducial
> types(round, square, bowtie, ect)
>
> What IPC spec contains this info?
>
> -Charlene Dwyer Lee
> [log in to unmask]
> contractor at Motorola
>
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