When I first heard the description of the problem, I was tempted to call it underetching, which leaves little freckles of copper all over the PWB, along with rough edges along the traces and an occasional etching spur.
But these are on top of the soldermask, so it looks like the soldermask epoxy was contaminated somehow.
In any case there is always the possibility of these either causing a direct short or contributing to noise crosstalk or potential arcing issues. I would give the fabricator a good a$$kicking. Keep the bad boards and insist he replace the lot, and you can give him back the bad boards when you get the new replacements. Don't give him the bad boards or you will just get them back in a reworked condition.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of stephengregory5849
Sent: Wednesday, January 28, 2009 10:26 AM
To: [log in to unmask]
Subject: Re: [TN] Metal particles on the PCB
Hi Ioan!
Got your pictures finally and have them posted now, they're here:
http://stevezeva.homestead.com/files/Photo_002.jpg
http://stevezeva.homestead.com/files/Photo_004.jpg
I've seen something like this before, and it was caused by overetching which caused plating slivers. Luckily, we found these before we populated the boards. We rejected the boards back to the fab vendor and had them replaced for new ones. We rejected them because of the possibilty that minimum electrical clearances were being violated.
Steve
----- Original Message -----
From: "Ioan Tempea" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, January 27, 2009 1:48 PM
Subject: [TN] Metal particles on the PCB
Dear Technos,
I have these PCB shaving a lot of small, but visible with unaided eye, Au or
Cu particles on them, all over. I have sent Steve a couple of images, but in
the mean time I would like to state my questions.
As per IPC-A-610D, 10.4.2, this is a defect condition. The exceptions at
5.2.6.1 say this would be acceptable if the particles were entrapped in
flux, which is not the case.
Big part of the litter goes away if wiped with alcohol soaked cloth, but not
all. Brushing will not remove the leftovers, which seem to be well attached
to the soldermask, but a solid nail scratching will.
First of all: is this a defect?
Secondly, are there any better methods to clean than what I have tried?
Plasma and other funky methods are not an option and solvent cleaning is
probably not either, since the boards are already populated on one side with
no-clean flux.
Thank you,
Ioan Tempea, ing.
Ingénieur Principal Fabrication / Sr. Manufacturing Engineer
30 ans déjà! - Already 30 years!
950 rue Bergar, Laval, Québec, H7L 5A1
t : 450-967-7100 ext : 244
Mtl : 514-990-5762
f : 450-967-7444
[log in to unmask]
www.digico.cc <http://www.digico.cc/>
P N'imprimer que si nécessaire - Print only if you must
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