[time-nuts] HP 5370B low frequency modulation

Arnold Tibus Arnold.Tibus at gmx.de
Thu Jul 26 17:21:52 EDT 2007

Magnus and the group,  
in hi-rel projects and in our space and satellite projects we have 
procedures to remove at least most of the gold cover eg. by 
presoldering the contact areas and then sucking both, tin and gold, 
away. Properly done the clean areas can then undergo the final soldering 
process. So far all our satellites do work very well and years longer 
than planned. I do not remember having had in 25 years ever real problems 
with good prepared solder joints. Of course, the best is avoiding gold 
contacts for solder joints at all and never use nickel plated surfaces for 
solder joints!
The NASA does have similar special procedures as the ESA.
The best is using adequate crimping processes where possible.


On Tue, 24 Jul 2007 04:36:40 +0200 (CEST), Magnus Danielson wrote:

>From: "Didier Juges" <didier at cox.net>
>Subject: Re: [time-nuts] HP 5370B low frequency modulation
>Date: Mon, 23 Jul 2007 21:12:39 -0500
>Message-ID: <000001c7cd98$1c8d3dd0$6601a8c0 at didierhp>

>> Brooke,
>> Thanks Bruce for the quick response, as always.
>> In my business, we typically dissolve the gold by dipping the solder cup in
>> a hot tin pot, which is replaced regularly, before soldering the wires. This
>> has been blessed by the major defense contractors for military applications.
>> Failure to do this typically results in weakening solder joints over time,
>> and delayed failures, particularly when there is mechanical and/or thermal
>> stress applied to the joint.

>Gold will dissolve very quickly into the Sn/Pb solder.

>If you have a too high gold content in the joint, it can form one of several
>Au/Sn mixtures which is brittle and will crack easilly. We had trouble with
>that under our BGAs so when the gold layer was too thick, the whole 400-500
>ball BGA could crack loose of the board if you accidentilly hit the rather
>flimsy cooling flange. On another board we glued a nut to the top of the BGA
>and hanged 50-70 kg of it and while the board was clearly bent the BGA was
>still firmly hooked to it. Now that's the difference between a few um of gold
>too much or not.

>There are other cases where the gold-plating is not an issue.

>This has been covered in public sources, so a dig around would give some


>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.

More information about the time-nuts mailing list