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August 2001

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Subject:
From:
"Tempea, Ioan" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 21 Aug 2001 09:13:00 -0400
Content-Type:
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Hi,



Since you are talking about a product that was good until not so long ago,
you have to look for what changed. I agree with Justin about the clearance
of the solder mask around the fiducials, it has to comply with SMEMA
Standard 3.1, available at http://www.ipc.org/html/smemastandards.htm. Maybe
this changed in your process, or maybe the specification changed (a new rev
of the artwork). Also, you must make sure that no marking ink is spilled on
the fiducials, especially if the silkscreen asks for markings in the area
neighbouring the fids.

Otherwise, just to keep it weird, maybe the customer lost the old programs
and the programmer cannot find the right light settings again. Or maybe they
have a new, less experienced programmer.

The bottom line is: try to find what changed.

Regards,
Ioan

> -----Original Message-----
> From: Braime, Justin [SMTP:[log in to unmask]]
> Sent: Tuesday, August 21, 2001 8:24 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] P&P can't locate fiducials
>
> Hi Mark,
> The fiducials on HASL boards can sometimes be a HASSLE (grin). The
> flatness
> of the finish is definitely an issue, but probably more so is the contrast
> between the fiducial and the surrounding circuit board. Are you leaving a
> sufficient border around the fiducial that is clear of solder resist?
> There
> is nothing worse than shiny HASL fiducial surrounded by nice shiny solder
> resist!
> I take it that the customer has tried adjusting the gain etc on their fid'
> camera?
>
> Justin
>
> > -----Original Message-----
> > From: Mark Hargreaves [SMTP:[log in to unmask]]
> > Sent: 21 August 2001 04:57
> > To:   [log in to unmask]
> > Subject:      [TN] P&P can't locate fiducials
> >
> > Hi All,
> > We've made boards for a customer for a few years.  They've  been very
> > satisfied with HASL finish.  Last month they started rejecting approx
> 40%
> > of
> > boards received (3 lots) because their P&P camera couldn't locate the
> > fiducials.  The coating looks typical to us (thickness & smoothness).
> > Customer can't see any difference between good & bad boards until
> they're
> > on
> > the P&P machine.  They say they haven't changed equipment, processes or
> > operators.  We say the same.  No HASL hassles from other customers in
> this
> > time period.  We tried reworking by wicking solder from the fiducials.
> > Customer rejected approx. 20% for the same reason.  They also say that
> > boards from another vendor are working fine.
> > Any comments/ ideas?
> >
> >
> > Mark
> >
> >
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