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November 2006

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Subject:
From:
Ian Hanna <[log in to unmask]>
Reply To:
Date:
Tue, 28 Nov 2006 11:36:22 -0500
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You sure that isn't the soldermask blistering?

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of pearl petras
Sent: Tuesday, November 28, 2006 11:12 AM
To: [log in to unmask]
Subject: Re: [TN] More delam

Answers:
  -FR4, 10 layer, .062" thick
  -No bake.  two manufacturers used, only one has done this.
  -We train and try to get assemblers to keep the temps down, but you
know assemblers...  :-)
  -I don't think the temps were overly high, either.  Not leadfree.
  -digital/RF applications, below 1GHz.

  I guess I want to know which option you would choose:
  -Scrap - expensive parts, customers crying for finished product
  -Try to fix (still unsure if possible, also see questions on
IPC-A-600)
  -Thermal stress them and if delam is stable, just let them continue,
  -Or just let them go (I didn't see anything, did you see anything?)

  Thanks.

stephengregory5849 <[log in to unmask]> wrote:
  Mornin' Pearl & Everybody!

Pearl, I got your pictures posted.
MAN, that's some strange delamination! What are the boards made of? FR4?
Polyimide? Do you bake the boards before assembly? What temperatures are
your soldering irons set at when you do your soldering? It doesn't look
like
they've been overtemped since I don't see any brown or "toasty" looking
laminate.

Hard to tell how deep the delamination goes...this looks kinda strange
to
me. I don't know if I'd trust these fabs or not. What's the application
if
you can share that?

-Steve-
----- Original Message -----
From: "pearl petras"
To:
Sent: Monday, November 27, 2006 10:02 AM
Subject: [TN] More delam


> Arggghh,
> More delamination. Looks like poor quality PCB's - a simple quick test
> adjustment to a component seems to be causing a lot of boards to 'pop'
in
> the same area. As well, others are popping in the area of a
> hand-installed edge connector, when they start to solder the center
pin.
> Even just tinning the pad does it sometimes.
> What would you do with boards like this?
> Would you try to fix it? How?
> Would you scrap it? There are some very expensive IC's on this board.
> Do you think it may go deeper than one layer?
> It is a 10 layer PCB
> IPC-A-600 states:
> -The imperfection does not reduce the space between conductive
patterns
> below the minimum conductor spacing. (OK - minimum conductor spacing
for
> low voltage is ~0.1mm)
> -The blister or delamination does not span more than 25% of the
distance
> between adjacent conductive patterns. (What does this mean? adj
patterns
> on the same layer as the delam? or do you consider 3-D, if the
conductive
> patterns are on a different layer but the bubble spans underneath
them?)
> -There is no propagation as a result of thermal testing that
replicates
> the manufacturing process. (would you try more hand-soldering, or
would
> you try a reflow process, how would you mimic it?)
>
>
>
> Steve, could I trouble you to post another few pics?
>
> Thanks all.


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