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Subject:	Re: ENIG
From:	R Sedlak <[log in to unmask]>
Reply To:	TechNet E-Mail Forum <[log in to unmask]>, R Sedlak <[log in to unmask]>
Date:	Mon, 18 Sep 2006 16:49:18 -0700
Content-Type:	text/plain
Parts/Attachments:	text/plain (49 lines)

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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