Dave;
Can you plate ENIG on top of soldermask residue? If you can, would the
board pass final inspection or bare board electrical test? We use White tin
and a flying probe tester. I think both of these processes would register a
Fail if we didn't have clean copper to plate white tin on.
Jac Kroeker
At 08:20 AM 03/11/2002 -0600, you wrote:
>Hi Moonman! One potential source of contamination would be a soldermask
>residue remaining on the pads after the soldermask application (due to a
>fabrication oops) prior to the application of the ENIG. Depending on your
>ability to get a reasonable sample, you can use FTIR analysis to determine
>if soldermask residue is remaining on the nonwetted pads. Good Luck.
>
>Dave Hillman
>Rockwell Collins
>[log in to unmask]
>
>
>
>
>
>Earl Moon <[log in to unmask]>@ipc.org> on 03/11/2002 05:57:13 AM
>
>Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
> to Earl Moon <[log in to unmask]>
>
>Sent by: TechNet <[log in to unmask]>
>
>
>To: [log in to unmask]
>cc:
>
>Subject: Re: [TN] ENIG AND NON WETTING
>
>
>Daan,
>
>As always, I appreciate your input. To clarify, the boards were freshly
>received from a major international supplier. I instructed our assembly
>house (the same major international supplier - how about that for strategic
>planning as the same boards, in volume will be, guess what, assembled by
>the
>same major international supplier in another location) to reflow and wave
>solder the solder samples. The supplier wave soldered the side in which I
>had little interest. It was the SMT side, with all the little bastard TI
>CSP's that held the most interest for obvious reasons or that should have
>been obvious to all as it's all I've been yacking about for two months to
>you all and all prospective suppliers.
>
>I got the wave results last week with the non wetting as I described. The
>wave solder process was "normal" to the major international assembly
>operation with flux type, flux application, conveyor speed, wave types,
>wave
>height, preheat temps, solder temp, and all the other stuff we all know and
>love about wave soldering and its process management requirements.
>
>The board showed, clearly, non wetting on some bottom side SMT pads, at
>about 50% non wetted. It also showed, clarly through hole pads about 50%,
>by
>quantity, non wetted with some obviously adhacent.
>
>My question, again, is what in the ENIG, over bare copper after SM
>application, is possibly affecting this type solderability. It's a mystery
>worth more investigation.
>
>Again, thanks Daan and I hope I clarified.
>
>Earl
>
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========================================================
Omni Graphics Ltd. 2 - 12760 Bathgate Way, Richmond BC, Canada V6V 1Z4
Tel 604-276-9717 Fax 604-276-2514
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