ENIG, and not oily after reflow.
Dean, no bag, I had torched it before reflow.
Unfortunately there does not seem to be an easy solution to this. I guess I'll sleep over it through the week-end.
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
T | 450.967.7100 ext.244
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De : [log in to unmask] [mailto:[log in to unmask]]
Envoyé : May-07-10 12:17 PM
À : TechNet E-Mail Forum; Ioan Tempea
Objet : Re: [TN] Wrinkling of conformal coating
Ioan,
Was the board by any chance fused tin-lead or HASL coated? If a solder mask is not processed according to the mask vendor's guidelines, especially in relation to UV exposure and thermal bakes, then the solder mask can absorb things like fusing fluids or HASL fluxes that then get sealed in by the heat of fusion or by contacting molten metal. You can sometimes see these coming out when you again expose the board to reflow conditions. This is often why I run "heated controls" when I am doing an ionic cleanliness witch hunt. If the bare board residue levels are relatively close to the heated controls, then the mask is probably good. If they are wildly different, then you have a potentially bad mask problem.
What did the board look like visually when it came out of reflow. Did it appear oily?
Doug Pauls
Ioan Tempea <[log in to unmask]>
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05/07/2010 11:07 AM
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Re: [TN] Wrinkling of conformal coating
In case you guys thought you got away by talking about alien espresso machines, I have one more question.
Took a bare board from stores and stuck it into the reflow oven. I have noticed smoke coming out from the tunnel while the PCB was in. Not huge or thick, but just enough smoke to notice it. Could this mean anything regarding the board, like not cured something, poor FR-4 or else?
Thanks,
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
T | 450.967.7100 ext.244
E | [log in to unmask]
W | www.digico.cc
N'imprimer que si nécessaire - Print only if you must
Dear Technos,
Back to orange peeling, this time concerning conformal coating, please see
http://ipc-technet.groupsite.com/galleries/photo/124230
The coating is applied with an Asymtek Century machine and is a Conap 1170
acrylic.
· The board is left curing in ambient temperature, no
acceleration. Starting with an even coating, in about 20-30 minutes the
liquid seems to move towards a certain area (no rippling at this moment).
After another 10-15 minutes the rippling effect sets in.
· We thought that due to the almost 2 minutes lag between the
coating of the first and last image, the drying of the coating layer is
not even and the one side curing first pulls on the liquid at the other
end. So we've cut the panel in 2, accelerated the machine, the problem is
still there.
· The boards are laid as flat as possible, maybe not perfectly
horizontal, but not worse than others with the same coating, that do not
show any issue
· Just to make it more difficult: grabbed a non-populated panel
from the stores, coated it, placed on the same flat surface, and guess
what: no issues.
The PCB has Taiyo PSR 4000 MP soldermask.
So I would need your guidance in clarifying where is this coming from and
how to fix it.
Thank you,
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
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