[time-nuts] HP 5370B low frequency modulation

[John Day]

See:

http://journals.cambridge.org/download.php?file=%2FMAM%2FMAM11_S02%2FS1431927605504483a.pdf&code=7eb044ef7101eff8a8274c4fdfabca59

and

http://www.tkb-4u.com/articles/soldering/sgons/sgons.php

There is also at least one US patent deals with using pure tin 
instead of gold for solderability. The problems are also well known 
to anyone working with flip-chip bonding where gold bumps have been 
used. Both tin and gold have been known to grow crystalline whiskers, 
one microscopy journal carried a paper a couple of years ago from 
Sandia Lab on the subject. Tin whiskering has been well known for many years.

John


At 11:21 AM 8/30/2007, Richard (Rick) Karlquist wrote:
>); SAEximRunCond expanded to false
>Errors-To: time-nuts-bounces+johnday=wordsnimages.com at febo.com RETRY
>
>Gold mixes with solder to from an "intermetallic" that
>suffers from "embrittlement".  I am not aware of silver
>solder being a remedy.  I have heard of assembly lines
>that do not allow any gold whatsoever in the building!
>I heard our assembly line manager at work just
>last week lecturing yet another engineer about NO GOLD.
>Period!
>
>Furthermore, gold plated brass connectors screwed into
>aluminum (with corrosion treatment) (no soldering) will
>corrode in a salt spray environment.  I guarantee it.
>We always used stainless for military work.
>
>Rick N6RK
>
>Brooke Clarke wrote:
> > Hi Didier:
> >
> > Would you elaborate on the comment "Gold plated connectors are a well
> > known example."  Do you mean when soldered with Lead Tin solder instead
> > of a silver bearing solder or something else?
> >
> > Have Fun,
> >
> > Brooke Clarke
> > http://www.PRC68.com
> > http://www.precisionclock.com
> >
> >
> >
> > Didier Juges wrote:
> >> ); SAEximRunCond expanded to false
> >> Errors-To:
> >> time-nuts-bounces+brooke=pacific.net+brooke=pacific.net at febo.com
> >>
> >> I have seen cold solder joints on thermal fuses and certain types of
> >> capacitors, while the rest of the instrument was fine with no sign of
> >> corrosion.
> >>
> >> I think it has to do with the metal used for certain component leads.
> >> Either
> >> they were never soldered well, or interface corrosion developed over
> >> time.
> >>
> >> Gold plated connectors are a well known example.
> >>
> >> Didier KO4BB
> >>
> >> -----Original Message-----
> >> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> >> Behalf Of Mike Feher
> >> Sent: Sunday, July 22, 2007 9:58 PM
> >> To: 'Discussion of precise time and frequency measurement'
> >> Subject: Re: [time-nuts] HP 5370B low frequency modulation
> >>
> >> Highly unlikely, but, possible, especially if it was in a corrosive
> >> atmosphere. Of course then I would expect to see evidence of corrosion on
> >> other components. ...
> >>
> >> Mike B. Feher, N4FS
> >> 89 Arnold Blvd.
> >> Howell, NJ, 07731
> >> 732-886-5960
> >>
> >>
> >> _______________________________________________
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