Rick,

0.040" is very good.

However, there's a strong issue related to the design: 0.040" is exactly the
size of the VIAs. If there's any in the field of view, the machine may get
confused (same stands for the PTH and the 0.060" fiducials). We are still
experiencing problems like this because of the high density of our
assemblies and, most of all, because of the machines we are using.

So, the free space around the fiducial is more important than the fiducial
size. Make it as big as possible.

Once again, the impact of the reflectiveness of the solder mask and the fact
that the fiducial is placed over the ground plane (so on dark surface) is
machine dependent. I have no problem with the Fujis, but I have two other
machine types that are extremely sensitive to this.

Regards,   Ioan

> -----Original Message-----
> From: [log in to unmask]
> [SMTP:[log in to unmask]]
> Sent: Thursday, July 01, 1999 8:21 AM
> To:   [log in to unmask]
> Subject:      [TN] FIDUCIAL SURVEY
>
> To all,
>
> What is the recommended size and shape of a fiducial?
> I believe I.P.C. recommends 0.040" round.
>
> What are your thoughts?
>
> Frustrated