I think a clue here to my reply to Dan is his statement that they are all on
the same net which is a very significant comment.
Dan do you have ANY gold on that net (or any "dark brown" pads that might
have been gold before they dissolved into the copper?
John
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of R Sedlak
Sent: Monday, September 18, 2006 4:49 PM
To: [log in to unmask]
Subject: Re: [TN] ENIG
Dan:
The ENIG process is pretty severe, with extended times in very hot (>180 F)
baths, loaded with chelates. These baths could be "cleaning" the pads for
you. Remember this, the first step in the ENIG process is key (the
catalyst) and if the catalyst does not deposit, it is game over for the rest
of the process.
As mentioned in another reply, residual Tin might be the issue, but also
incomplete development of soldermask, with essentially invisible residues
remaining, could also be the cause.
Can you pre-identify probable problem pads, and test?
I may also be able to assist with a band-aid type step, which would overcome
incomplete developing issues.
Rudy Sedlak
RD Chemical Company
Dan Skweres <[log in to unmask]> wrote: We have, at times, had an outside
plating service have difficulties with plating of ENIG on our bare boards.
The interesting anomaly we have encountered is lack of plating on certain
pads. They tell us there is something on the surface of the pads but when
they return the panels to us we micro etch (copper looks beautiful) and all
pads look similar in appearance. We even took a panel and coated immersion
white tin with out problems. This tells me that there isn't any thing on the
surface of the copper. There is one thing I did leave out. The pads that
aren't taking ENIG all happen to be in the same net. Has anyone encountered
this? It's almost like there is a charge being created in certain nets not
allowing the ion exchange to happen. Could it be entrapped chemistry within
vias? Any help and/or direction would be greatly appreciated.
Thanks,
Dan Skweres
Engineering Manager
Bartlett Manufacturing
Phone:847-639-2102 Ext.#230
Fax:847-639-8838
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