Wayne,
For a second or two, that idea flashed by here too, but I thought of all
specials and tools and things that has to be made to fix it. We resistance
solder thin lids to small Kovar packages, have a SSEC machine for that, big
as a house. But it does not have that current capacity. A car
battery...hmm..not bad idea. Or many in parallel. If one got enough current,
then time is the other parameter. I can easily machine heavy copper
electrodes in our shop, and cables not a problem. We have some that can
carry thousands of amperes. And you need a fixture for holding the package
and electrodes steadily with high pressure. One way would be to design the
electrodes in a way that they make a circle around the feedtrue...one on
each side. That would create a dense and well defined current flow.
I love experiments, will think it over.
Inge
----- Original Message -----
From: "Thayer, Wayne" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, September 24, 2008 8:17 AM
Subject: Re: [TN] Soldering SMA to heavy RF packages, need advice
Hi Inge!
Nickel is pretty lossy, so you could possibly heat with electrical
energy. Still lots of current required--probably on the order of
100A/mm of nickel. Nickel doesn't conduct heat real well either, so you
would want to drive the current pretty close to where the solder needs
to be melted. I'll bet a few days of playing with an arc welding power
supply would get you a process. Or you could just use a car battery and
some jumper cables and see what happens!
Problem I see with this technique might be package warpage due to
differential coeff of expansion and the local heat, similar to problems
of using a torch, but the electrical would have much better control.
Wayne Thayer
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
Sent: Wednesday, September 24, 2008 10:46 AM
To: [log in to unmask]
Subject: Re: [TN] Soldering SMA to heavy RF packages, need advice
Mike,
THAT was new to me! Good start, I'd say, many thanks. Hope our machine
can manage 260 C.
Inge
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Sewell
Sent: den 24 september 2008 16:33
To: [log in to unmask]
Subject: Re: [TN] Soldering SMA to heavy RF packages, need advice
Inge,
Galden makes fluids that go to 260C...
http://www.solvaysolexis.com/static/wma/pdf/9/7/7/0/Galden%20VPS.pdf
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
Sent: Wednesday, September 24, 2008 9:26 AM
To: [log in to unmask]
Subject: [TN] Soldering SMA to heavy RF packages, need advice
TNetters godday.
Target is very large metal packages with bright nickel finish. Imagine
soldering hermetic feedtrues. Nickel needs higher temperature and longer
exposure time than copper, silver, gold and other metals. Vapour phase
soldering is maximum 218 Centigrades, which I believe is not high
enough. Iron soldering is not practical for launches. IR oven could be
an idea if we add protection gas. Hot gas stations (Nitrogen)seem to be
too lame. Resistance soldering not tested, unknown for SMA. Torch heard
of, ought to be impractical, will burn flux and miscolor package. Laser
soldering not practised.
Anyone out there with experience from this kind of soldering?
Inge
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