Brian,
Thanks!
I know the difference between a volt and an ohm and quite a bit about solderability, but I don't profess to know very much about the inner workings of electrical components.
Bev
--------------------------
Sent from my BlackBerry Wireless Handheld (www.BlackBerry.net)
-----Original Message-----
From: Brian Ellis <[log in to unmask]>
To: TechNet E-Mail Forum. <[log in to unmask]>; Bev Christian <[log in to unmask]>
Sent: Sun Oct 19 03:10:33 2003
Subject: Re: [TN] Question about wetting
Bev
As the components are trimmer capacitors, I don't think ESD would be an
issue. If they were jigged in a metal frame that could be earthed after
they were treated.
There is another point that should be considered: the trimmers may be
lubricated with a conductive grease; this could be removed by water washing.
Brian
Bev Christian wrote:
> 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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