It's fine Dave ; you definitely did not leave THAT impression ; that was
the beaut .
True; we have it "easier" here ; without validated process or change we
can not even pull button on P&P .
But with the "inspection" with XR for enviro life ; yes the amount of
solder visible would make me feel good ; but the invisibilities of joint
quality would not make it quite that comfortable , especially for
demanding environments .
One of our fellows here used to make modem cards on FR4 laminate and
uttered one day a remark (not a polite one) on the reject ratio trap he
set on his subjects ( tested cards prior to depaneling with a top 99.xx
yield , and no prizes for guessing he did not get that AFTER depaneling
! [-7%!]) . Fixed by redesigning and resequencing the process .
I personally think the shorts are in the past and not reliability
relevant (apart from "rework" damages) ; opens are the issue nowadays .
Not much to do for XR .

Paul Klasek
http://www.resmed.com
> ----------
> From:         David D Hillman[SMTP:[log in to unmask]]
> Sent:         Saturday, 1 August 1998 4:10
> To:   [log in to unmask]
> Subject:      Re: [TN] Glenbrook x-ray??
>
> 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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