Yes, thank you for the reference, I wasn't aware of it.
I think the key word there is "When specified", because
we were told since we didn't specify internal cleanliness,
the vendor shouldn't be held responsible for it.
I apologize for asking a question about "core quality"
without providing the core material, but I just recently
got the report from our vendor in Taiwan listing what was
used on that batch. The cores were IS400 from Isola.
The other "lessons learned" for me (in case it helps
anyone else out there) was the fact that although the
material breakdown is usually listed in kiloVolts per mil,
the IPC-2221 design guideline paragraph 6.3 instructs us to
use Table 6-1 for voltage requirements, even in the z-axis.
This means that designs we have here with 600v traces
on 6 layers must use a .5mm dielectric. 20 mils
between each one? I've never seen that done...
(IPC-4101 lists 40kV for .5mm, by contrast)
So naturally, the end result is that this problem can be
chalked up as a design flaw, because I should have
used thicker material according to IPC-2221
Thanks again everyone for the help and advice,
Jack
.
On 11/22/07, Sherif Refaat <[log in to unmask]> wrote:
>
> Jack;
>
> IPC-6012 Paragraph 3.10.3 reads "*Cleanliness of Inner Layers after oxide
> treatment prior to lamination* When specified, inner layers *shall *be
> tested per 3.10 and meet the requirements of the procurements
> documentation."
>
> Par. 3.10 calls for solvent extract method to measure cleanliness.
>
> Sherif,
>
> ----- Original Message ----- From: "Jack Olson" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, November 22, 2007 11:28 AM
> Subject: Re: [TN] Core Quality Issue?
>
> 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<http://www.frontdoor.biz/PCBportal/corequestion.jpg%3Chttp://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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