Jason,

Am I missing something?  If you are fluxing with a water soluble, aren't you violating
your customer's desire to use a no clean.  I would assume that your customer is
concerned about ionic residue since they a specing a no clean.  I would be more
concerned with the approach you are using than I would with just soldering with the
water soluble.  Wouldn't a full solder cycle be less likely to leave ionic
contaminates?  I guess that is a question for a flux guru.

I have only played with OSPs only a little and I don't run nitrogen in any soldering
operations.  The first thing I didn't like about them was the poor spread of the solder
on the first pass.  I could put a spot of paste on a pad and it would not wet much past
the area it was deposited at.  I also thought the wetting angles, though acceptable,
were greater than I am used to seeing.

I believe nitrogen is necessary in all soldering operations in order to be successful
with an OSP.  Anyone - please correct me if I am wrong here.




Jason Smith wrote:

> I am having problems with wave soldering OSP boards.  After the boards have seen
> a heat cycle (reflow), they are impossible to get hole fill on topside without
> first cleaning the boards to remove either oxidation or hardened OSP.  I don't
> know which one I have because I haven't had them analyzed yet.  The flux used to
> wave solder the boards is a very weak customer dictated rosin no clean flux.
> The OSP is Cu106A.  I am not familiar with OSPs.  They won't do HASL either.
> Any insight?  Suggestions?  Assistance?
>
> As it stands now, the process is to flux with high solids water soluble/heat to
> clean the board-->wash off flux-->immediately wave solder with rosin containing
> no clean.  This is not a production process........
>
> Jason Smith
> Process Materials Engineer
> Lexmark Electronics
>
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