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July 1998

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Subject:
From:
David D Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 31 Jul 1998 13:10:18 -0500
Content-Type:
text/plain
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text/plain (98 lines)
Hi TechNet - Your right Steve/Paul, it is not necessary to xray and test
every BGA on every assembly (I didn't mean to leave that impression). A
reasonable sampling in plan in conjunction with good process control as
outlined in JSTD-001 allows for low process cycle time and reasonable
costs. I have seen some examples of where several assembly houses have a
good handle on the placement gauge R&R, inspect their solder paste print
and have tuned in their reflow profile - they do only sample electrical
testing, no xray and are producing quality product. I think the amount of
"inspection" is also part of an assemblers comfort level for the use
environment their product has to live in.

Dave Hillman
Rockwell Collins
[log in to unmask]





"Stephen R. Gregory" <[log in to unmask]> on 07/30/98 06:48:32 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to [log in to unmask]

To:   [log in to unmask]
cc:
Subject:  Re: [TN] Glenbrook x-ray??




In a message dated 98-07-30 19:14:35 EDT, you write:

 [log in to unmask] (Paul Klasek)
 To:    [log in to unmask]

 I concur with David ; have been watching this discussion for some time
 and kept out as I thought perhaps I'm the odd one out in extreme as
 usual ; but since Dave cracked the pot the way it is :
 If the process is out of window to such a degree this kind of machinery
 is needed ; I'd say $ much better spend would be in the process gear ; not
 inspection gear . >>

Hey there Paul!

Well since you and Dave started this, I'm gonna jump on the bandwagon too.
I
asked the question that I'm about to ask on another web forum a while back,
and the reponses were kind of guarded...(it was like they didn't want
anybody
to see them answer with what some may percieve the wrong response). But my
question was; why does it seem that if you want to do BGA, the consensus is
you need to have xray capability?

I know that xray is a tool that will allow you to see things that you
normally
can't see, but is it REALLY necessary? It would seem to me that if you can
make sure that you lay enough paste down, put the part where it's supposed
to
go, and got your oven cranked-up with enough heat, you're in the BGA
business...and you can do all that stuff without an xray machine.

"But you can't see the solder joints dross-breath, that's why you need an
xray
machine.." some may say. But I didn't see everybody getting spooled-up
about
having xray when we started putting decoupling capacitors beneath DRAM
years
ago...can't see those solder joints either. So, is it really necessary?

-Steve Gregory-

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