time-nuts-boun...@febo.com wrote on 03/21/2010 10:43:40 PM: > From: > > Bob Camp <li...@rtty.us> > > To: > > Discussion of precise time and frequency measurement <time-nuts@febo.com> > > Date: > > 03/21/2010 10:52 PM > > Subject: > > Re: [time-nuts] HP 5065A rubidium lifetime > > Sent by: > > time-nuts-boun...@febo.com > > Hi > > One thing to be careful about with all this tinning of strange materials: > > There is indeed a way to get it *almost right". The lead wets > with solder and the lead will indeed pass a tug test. Thermo- > cycle the lead a dozen times and you can pull it right out of > the solder. > > If you are going to do this on any "mission critical" devices, > it's best to check the result fairly carefully until you are > sure of your materials and technique. > > -------------------- > > While I have no direct experience with a problem, I also > suspect you would want to keep your stash of phosphoric acid > away from any un-tinned kovar leads. Kovar it's self will not > solder, but it's oxide will. Strip the oxide and you have a > significant problem. You have to get the stuff very hot to re- > form the oxide you need.
I'm surprised by this. In the 1970s, I had the kovar leads on some nixie tubes become unsolderable (probably due to minor corrosion - the leads looked OK), and solved the problem by dipping the leads in dilute sulfuric acid (battery acid diluted 10:1, so about 2% strength) for a few seconds and washing off in tap water. I would assume that the acid pickling removed an offending oxide layer. Joe Gwinn _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.