Bev Christian wrote:
> Steve and other TechNetters,
> We have a what is probably an "upper middle class", off-line, 2D x-ray
> unit.
> It currently sits in our Materials Engineering Lab. We use it during
> qualification of all new board codes containing BGAs. We run a few
> boards
> out of the first lot of boards and then the production guys are off to
> the
> races. It is great for solder balls, shorts and voids, but opens are
> indeed
> a problem.
>
> We also use it for looking for solder balls and metal slivers in other
> work,
> examining bond wires in components, proper mating of male and female
> connectors and other odds and ends.
>
> We also provide these services to other sites so it doesn't sit idle.
> I
> think it would be hard to justify for a small to medium plant's use
> only.
>
> regards,
> Bev Christian
>
> > ----------
> > From: Stephen R. Gregory[SMTP:[log in to unmask]]
> > Sent: Friday, October 02, 1998 2:32 AM
> > To: [log in to unmask]
> > Subject: Re: [TN] : Assy: Xray Utilization
> >
> > In a message dated 10/01/98 6:25:26 PM Pacific Daylight Time,
> LonerLSZ
> > writes:
> >
> > > Steve,
> > > We do a percentage of lot inspection for ISO. If you are
> considering
> > > becoming certified then you will need to do process control which
> will
> > > require a need for inspection. BGA's can only be inspected by
> x-ray so
> > how
> > > else would you do it?
> > >
> > > Linda
> >
> > Hi Linda!
> >
> > How would I do it you ask? Easy, we got this guy workin' for us
> named
> > Clark Kent and he...what?....not buyin' that are ya?...didn't think
> ya
> > would...hehehe.
> >
> > Seriously, my logic is that when you're pumping out production
> boards, you
> > should have your processes dialed-in.
> >
> > Production scenario: You've got your stencil tweeked, paste is just
> the
> > stuff
> > you want, and you know you can print 15 times and then program a
> cleaning
> > cycle to keep the image crisp. You also know that each print takes
> 3-grams
> > of
> > paste, so you'll program a dispense cycle in every 30 prints to keep
> a
> > nice
> > roll of paste in front of the squeegee. You know your placement
> programs
> > are
> > dead on because they came from cad data, you also verified that on
> your
> > first
> > article. Reflow profile was created, plotted, and given a fine
> adjust for
> > the
> > first article, which was followed with the xray inspection. Now
> you're
> > gonna
> > run some revenue.
> >
> > You've got your people doing periodic, random, process checks and
> logging
> > them
> > after solderpaste print, placement, and reflow, and they're doing a
> great
> > job
> > making sure that happens. So you tell me, when should I fire up the
> ol'
> > x-ray
> > machine again? When would I r-e-a-l-l-y need to if what I described
> above
> > was
> > happening? See my point? Things normally don't all of a sudden go
> wacko
> > for
> > three boards and fall back in line again. If you have your process
> set and
> > being monitored, I have a hard time coming up with a good reason to
> > justify x-
> > ray for anything other than initial process set-up and verification.
> If
> > you
> > find something during a production run, in my mind, it's too late.
> What
> > would
> > you do? Stop production and go back and x-ray all the boards that
> were
> > built
> > from the last time a board was
> > x-rayed?
> >
> > Don't get me wrong, I'm not saying what you're doing is a waste, but
> these
> > are
> > things that I've been thinking about trying to really justify the
> expense
> > of a
> > x-ray. Will it really be earning it's keep while every other machine
> is
> > producing something? Food for thought huh?
> >
> > -Steve Gregory-
> >
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Hi!
Just the same with our Nicolet as Bev Chrisian wrote.
It's useful in all those applications and failure analysis.
Gaby
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