Thanks folks,
I am really impressed by the quantity, and quality of course, of the answers I get!
I agree that it looks like Cu diffusion due to Ni problems, but it seems the Ni is there, see top layer on the last 3 images. Looks rather rough though. Unfortunately did not ask for thickness measurements.
Now, reliability wise, is there anything wrong, even if I'm having Cu diffusion? I mean all components are properly soldered and Cu oxide is stable, does not aggravate with time. Also, since the oxidized places are to be probed in ICT, all should be OK still, since Cu oxide is conductive.
Is there any worry?
Thanks again,
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
T | 450.967.7100 ext.244
E | [log in to unmask] <mailto:[log in to unmask]>
W | www.digico.cc <http://www.digico.cc/>
N'imprimer que si nécessaire - Print only if you must
De : Ioan Tempea
Envoyé : October-24-11 7:54 AM
À : 'TechNet E-Mail Forum'; [log in to unmask]
Objet : RE: Discoloration on plated over vias
Hello,
Forgotten an important thing, I'm talking about ENIG finished boards. The process uses water soluble flux and aqueous wash, no saponifier. The Ni layer is there and no Cu diffusion could be detected.
I'm digesting the answers that came in over the week-end, but I would appreciate even more replies.
Could unwashed flux generate this aspect? I've seen unwashed boards in the past, but the pads were green and not red!
Thank you all,
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
T | 450.967.7100 ext.244
E | [log in to unmask] <mailto:[log in to unmask]>
W | www.digico.cc <http://www.digico.cc/>
N'imprimer que si nécessaire - Print only if you must
De : Ioan Tempea [mailto:[log in to unmask]]
Envoyé : October-21-11 4:26 PM
À : [log in to unmask]
Objet : [SMART] Discoloration on plated over vias
Dear Technos and Smarts,
I got this issue, see http://ipc-technet.groupsite.com/gallery/21662
So 6 layer, 2oz Cu per layer PCB, epoxy filled vias and plated over. After assembly we see 4-5 vias having reddish stains, on most boards. Had it analyzed, no trouble with via integrity, no cracks in cover plating, no migration of fluids from inside out. FTIR does not detect any surface contamination.
Au plating thickness stands at 2.09 micro inches.
Nothing special detected in the stains, so the lab concluded what we see is an optical effect due to a certain roughness of the Cu. The logical conclusion is no issue, cosmetic defect.
However, our end customer, high reliability, want to know what the stains are and want absolute confirmation that long term reliability is not affected. Also, we've been warned that no such issues will be tolerated on future lots.
My questions to your infinite knowledge is: have you seen this before? How can I convince the customer everything is OK? What is the root cause and how can I get rid of the issue?
Many thanks,
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
T | 450.967.7100 ext.244
E | [log in to unmask] <mailto:[log in to unmask]>
W | www.digico.cc <http://www.digico.cc/>
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