JAck,
But U mentioned that the shorting is across the core (pink core in
x-section).....cleanliness on the core is not the reason for arcing across the core.
Maybe BAD LAMINATE is the problem.
Rush
Accurate Engg Inc.
_www.accueng.com_ (http://www.accueng.com)
In a message dated 11/22/2007 8:29:54 AM Pacific Standard Time,
[log in to unmask] writes:
I don't know what the base material is, but I'll ask on Wednesday.
We have a big meeting scheduled on Wednesday with the middleman
who is "managing" the vendor in Taiwan. Haven't heard from the actual
vendor yet. I don't even have a contact I could call, believe it or not!
I just wanted to be as prepared as I can be for Wednesday, because
this type of discussion is not my cup of tea...
We had a company called Foresite do some analysis, who reported
internal uncleanliness, the middlemen says we never specified anything
about internal cleanliness (believe it or not!) and I was just wondering
if there might be a problem with the core material itself, which would
mean the boards are screwed before they even start, right?
but while I'm thinking about it,
Does IPC have any statements about internal cleanliness?
I will cheerfully supply more details after Wednesday if I'm not bogging
down the list too much...
Jack
On Nov 22, 2007 2:23 AM, arnaud grivon <[log in to unmask]>
wrote:
> Jack,
>
> As others said, PCB manufacturing quality could have been more easily
> suspected if the filamentation originated from a PTH.
> In your case, it looks like you have evidences of copper both in
> pre-preg and inner cores.
> Assuming the base material is the same for pre-pregs and cores, I would
> rather lean towards a material problem.
> ...which makes me come back to my initial question from your previous
> post: what is the base material used for that PCB?
> Best regards,
>
> Arnaud Grivon
>
> Jack Olson a écrit :
> > Sorry to re-start a previous discussion, but I'm still dealing with a
board
> > failure and I'm trying to learn fast.
> >
> > I received a higher-resolution picture of a board problem we are having
> >
> >
http://www.frontdoor.biz/PCBportal/corequestion.jpg<http://www.frontdoor.biz/PCBportal/corequestion.jpg>
> >
> > and if I look at it closely, I can see the dividing line between all ten
> > layers of dielectric.
> >
> > By looking at which way the copper is located from each dividing line, I
can
> > tell which are cores and which are prepreg (because the prepreg layers
will
> > flow "around" the copper features)
> > For example, the thin pinkish layer is a core. Am I on the right track
so
> > far?
> >
> > So, our problem is a 120V end-of-line test frying two out of every
hundred
> > boards right through the pinkish core material with the white streak
through
> > it
> > (3.2 mils, which should handle a few kilovolts at least, right?)
> >
> > So here's the question:
> > Should I be questioning the material quality rather than the bare-board
> > manufacturing process itself?
> >
> > I realize you guys have already been generous with helping me on this,
so I
> > hope I'm not pushing your patience...
> >
> > onward thru the fog,
> > Jack (aka "the new guy")
> >
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