Hi Again Pearl!
One more question; is the PCB multi-layered, or is it double sided? It's
hard to tell, but it almost looks double sided to me. I know the guide
that I linked you to doesn't specifically address edge delamination, but
it sort of gives you an idea of how you would go about PCB base material
repair. I kind of look at it as fiberglass repair. Simplistic I know,
but it's kind of like that with a few more complications thrown in.
From the pictures that you sent me, I would say all of the boards in the
pictures are repairable.
http://stevezeva.homestead.com/files/delam5corner_exceedIPC.JPG
http://stevezeva.homestead.com/files/delam7viatracecorner.JPG
http://stevezeva.homestead.com/files/delam12bubble.JPG
The one that I would worry about is the delam7viatracecorner.jpg since
it does go past some vias. But if the board is just double sided, and
those vias are only bringing up a test point, I might repair that one
too.
I know that you probably don't see any real gaps where to shoot some
epoxy in, you will need to get a really small gage needle and force it
in as best you can, then clamp the area down with a small clamp until
the epoxy cures. Another thing to do is make sure that the edges of the
PCB where the delam is is covered with a thin coat of epoxy to seal it
off.
-Steve Gregory-
________________________________
From: pearl petras [mailto:[log in to unmask]]
Sent: Monday, November 06, 2006 2:48 PM
To: TechNet E-Mail Forum; Steve Gregory
Subject: RE: [TN] Delam from separating boards
I don't see anything for edge delam, there.
End use - part of power supply for communications equip.
Some delam goes into traces, some goes fully past vias - the board is
small and densely featured. Many delam areas have components mounted on
the top side of the board. They aren't spread so bad that you can
really see into it to shoot some epoxy easily. I know the vias and/or
internal trace areas are probably unsalvageable, but if it isn't into an
area with an internal trace or via, and there are components over the
area, do you need to rework them, and if so, how?
Steve - could you post a few pics? Just a few examples.
Steve Gregory <[log in to unmask]> wrote:
Hi Pearl!
Just how bad is the delamination? What is the end use of these
boards?
If the delam goes into traces, that may be problematic, but not
the end
of the world. If it's just base board material, that can usually
be
repaired fairly easily. It's just a matter of getting some good
two-part
epoxy (I use Loctite 0151), and patching everything together.
Here's a link for some good guidelines for base board repair:
http://www.circuitrework.com/guides/3-0.shtml
I feel your pain when it comes to re-scoring boards that haven't
been
scored deep enough and have been already built. I've been there
and done
that and even got a tee-shirt. It ain't no fun, but I don't have
to tell
you that. Sometimes you have to do what you gotta do.
I found that when you have to go back and make the score deeper
with an
exacto knife, patience is key. You have to understand that it's
going to
take some time. You need to go over the existing score, scores
and
scores of times (pun intended). It's better to go over the score
with
your knife many times lightly, rather than trying to make deep
cuts,
because it's then when your knife comes out of the score line
and goes
into nearby traces. You also need to go over the score from both
sides
of the board, not just one side.
Good luck!
-Steve Gregory-
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of pearl petras
Sent: Monday, November 06, 2006 11:37 AM
To: [log in to unmask]
Subject: [TN] Delam from separating boards
We had some v-scored boards, with components so close to the
edge that
we could not use a depanelizer to separate them. (I know, I
know, root
cause - no DFM)
On top of that, the V-score done was basically just a lightly
etched
line.
Some enterprising people used some exacto blades to try to score
them
further, and then just applied brute strength...
I have been told that most delam is non-repairable. Is that so?
We
have an extremely high percentage of a build that will need to
be
written off, if so.
If not, any thoughts on where to go for tips and tricks on how
to
repair?
How do you determine what is repairable and what is not?
Switching away from RoHS to other headaches for a bit...
Thanks in advance.
________________________________
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