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November 2006

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Subject:
From:
Dan Skweres <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dan Skweres <[log in to unmask]>
Date:
Tue, 28 Nov 2006 16:25:34 -0600
Content-Type:
text/plain
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text/plain (145 lines)
Gloria,
If you're referring to pictures of the delam I am describing I do not have any. I know of this by word of mouth. Without implicating any one... It was a good source. Keep in mind certain oxide alternatives not all. And of course you have to keep in mind the application method (dip tanks verses conveyor).
Dan S.
>>> "Gloria Brown" <[log in to unmask]> 11/28/06 04:11PM >>>
Where are those pictures posted?

Gloria Brown
phone 906-932-5970  ext. 26
fax  906-932-9822
[log in to unmask] 


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dan Skweres
Sent: Tuesday, November 28, 2006 3:31 PM
To: [log in to unmask] 
Subject: Re: [TN] More delam

Are you positive it is an FR4 ANSI grade? The reason I ask is that some
fabricators will use a product IS410 when a high temp FR4 material is
requested. I have heard of bonding issues with multi-layer boards, in
particulliar power and ground layers, when the inner layers are treated with
certain alternative oxide coatings. There is something to do with the
incompatibility with the phenolic material and the coatings. 
Dan S.

>>> [log in to unmask] 11/28/06 10:11AM >>>
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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