Hi Ioan,
I think the Halo looks like a contaminant and could be a problem. It might be thick mask but my vote says contaminant under the mask.
Why not probe the mask and see if the discolorations is on the surface of the PWB or not.
Best regards,
Paul
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Friday, June 19, 2009 3:49 PM
To: [log in to unmask]
Subject: [TN] PCB problems
Dear Technos,
I have a few questions regarding a funny lot of PCBs we've received. Steve was kind enough to post the pictures, see
http://stevezeva.homestead.com/files/non_uniform_hasl.jpg <http://stevezeva.homestead.com/files/non_uniform_hasl.jpg>
http://stevezeva.homestead.com/files/non_uniform_hasl_1.jpg <http://stevezeva.homestead.com/files/non_uniform_hasl_1.jpg>
http://stevezeva.homestead.com/files/via_halo.jpg <http://stevezeva.homestead.com/files/via_halo.jpg>
http://stevezeva.homestead.com/files/via_halo_detail.jpg <http://stevezeva.homestead.com/files/via_halo_detail.jpg>
Out of the pack of 15 that I have inspected, most of them have some weird halos around all the vias, but no such issue around the component mounting holes. The pictures show the worst board, the rest have it to a lesser extent. What is it? Should this be a reject? Is this anything we should admonish our fab about?
Secondly, the SnPb HASL, is irregular on the pads, which is not out of the ordinary, but on some boards looks like in the pictures. I hesitate calling this de-wetting, since the wetting angles are good. Is it de-wetting? Should we reject the boards? I will paste the worst board I find and reflow it, to get an idea what happens during soldering, but I should also be able to help the incoming inspectors draw a line between good and bad in visual inspection of future lots...
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
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www.digico.cc <http://www.digico.cc/>
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