aaaaaaaaahhh...!
I had the wrong mental picture, sorry!
I couldn't imagine a camera trying to find an empty spot (donut hole)
thanks for responding,
Jack (am I still "the new guy" around here? HA.)
On 10/6/06, Gary Ferrari <[log in to unmask]> wrote:
>
> Heather,
>
> What is happening is that the fiducial is isolated and is attracting
> excessive plating. What the supplier is asking for is to add some
> non-functional copper around the fiducial in order to balance the
> plating. He requests a ring of copper, and we imagine it as a donut. In
> essence, he probably means a large ring of copper for thieving, which
> will probably work.
>
> Gary Ferrari
> FTG Circuits
> Director, Technical Support
> 860-350-9300
>
> Heather Gregg wrote:
> > Some more information has come my way... (these things happen since I'm
> > in the Netherlands and my employer is in Ohio)
> > Apparently there is a dome of SN100 building up on the fid. Machine
> > recognition is failing due to shadows and/or the fid appearing too
> > small. If they crank the lighting level way down it will see most of the
> > fids, but it's not consistent. The supplier has suggested a bull's eye
> > pattern, not a doughnut (my bad, sorry). The supplier says the addition
> > of a copper ring around the fid will solve the plating/leveling
> > problems. To me it sounds like the supplier has processing problems so
> > I'm reluctant to change our fid just for that. What's your opinion now?
> >
> > Thanks for all the responses so far. It's a great help.
> > Hg
> >
> >
> > Jack Olson wrote:
> >
> >> I don't think adjusting the clearance is going to solve her problem,
> >> and that would be an expensive experiment (in time if nothing else)
> >> for no gain. We use silver finish here, so I can't comment on that
> >> except to say there has to be a bazillion boards with her finish
> >> being built successfully, so I suspect the machine itself.
> >>
> >> just a guess, though
> >> Jack
> >>
> >>
> >> On 10/6/06, [log in to unmask] <[log in to unmask]> wrote:
> >>
> >>>
> >>> Jack and Hg,
> >>> I almost hate to disagree, but the equipment will likely work better
> if
> >>> you
> >>> use SMEMA standard fiducials.
> >>> 1mm diameter copper with a minimum of 1mm clearance to anything
> >>> all around.
> >>> No copper, no mask, no nothing within 1mm of the fiducial dot.
> >>> Unfortunately using Sn100 finish does not allow a shiny dot for the
> >>> equipment to find, so you need the minimum clearance to help.
> >>> If you can try a coupon with multiple variations of clearance .5mm,
> 1mm,
> >>> 1.5mm, round, square, etc.
> >>> I am relatively sure you will find the SMEMA standard of 1mm round
> with
> >>> 1mm
> >>> round clearance the best, but the finish may have more effect and
> there
> >>> fore
> >>> need something to help compensate.
> >>> Good luck,
> >>> FNK
> >>>
> >>>
> >>>
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