Brian,
Nortel tried this in the nineties and had electrostatic damage problems.
Bev
-----Original Message-----
From: Brian Ellis [mailto:[log in to unmask]]
Sent: October 18, 2003 3:06 AM
To: [log in to unmask]
Subject: Re: [TN] Question about wetting
If the parts are not hermetic (i.e., may absorb water and not be able to
get it out again), then there is no reliable solution to your problem.
OTOH, if you're sure you can get the water out again without any
internal damage having been caused, then any of the described methods
may be used.
However, there is another possibility which may just work while on
reels, a reductive plasma. The obvious one would be hydrogen or a
mixture of hydrogen and a hydrofluorocarbon, but I have no idea of
anyone who could do this safely -- maybe the plasma machine makers could
advise you. Obviously, you would require to do tests to make sure that
the components (or reels) were not damaged.
Brian
John Foster wrote:
> One big problem we have is that the parts are not hermetic. In fact we are
> looking at a alternate part because of this. I am going to look into the
> mechanism of oxidation.
>
> Thanks for all of the ideas so far.
>
> John
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Bev Christian
> Sent: Friday, October 17, 2003 11:42 AM
> To: [log in to unmask]
> Subject: Re: [TN] Question about wetting
>
>
> John,
> Are they non-solderable because the tin has oxidized, the tin has been
> consumed as tin/nickel intermetallic that has then oxidized or the tin was
> so porous the nickel has oxidized? Also are the parts hermetic? If they
> are hermetic and you are sure they are just surface tin oxidized, throw them
> in some dilute EDTA, wash with DI water, IPA and then retape. If it
> anything else you would have to use acid to dissolve off whatever layers are
> there and then immediately re-tin.
>
> Then there is an electrochemical way to strip off the bad layers called
> ROSA. But this assumes they are either hermetic or can be fixtured to just
> immerse the leads. I wouldn't want that job! And Dave Hillman's ROSA
> unit is not up and running at this time. EMPF's??
>
> regards,
> Bev Christian
> Research in Motion
>
> -----Original Message-----
> From: John Foster [mailto:[log in to unmask]]
> Sent: October 17, 2003 2:14 PM
> To: [log in to unmask]
> Subject: [TN] Question about wetting
>
>
> I have a large inventory of trim capacitors that have exceeded the
> manufacturers shelf
> life by 2 years. Solderability testing has revealed inadequate wetting. The
> parts are on
> tape and reel. The plating is a thin layer of tin over nickel. We believe we
> have a oxidation problem. Does anyone have any ideas AT ALL on how we can
> recover these
> parts. The part has gone obsolete I have 86,000 of these things that I
> really really need to use.
>
> Any help would be appreciated
>
> Thanks
> John Foster
>
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