Lead-Free Solder: Weird Behavior

I read in sci.electronics.design that Daniel Haude wrote (in ) about 'Lead-Free Solder: Weird Behavior', on Tue, 22 Mar 2005:

Oh, that's not playing fair! You aren't allowed to introduce a 14 T magnet halfway through the speculations! (;-) Even so, your current-carrying interconnections are prey to electromechanical disruption. And BE VERY careful about using tin (Sn) at even modestly low temperatures. Look here, and elsewhere with the search string tin*allotropes:

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ISTR that a few years ago, doubt was cast on whether 'grey tin' is really an allotrope, rather than an intermetallic compound, but it seems to have been redeemed.

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Regards, John Woodgate, OOO - Own Opinions Only.
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John Woodgate
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It also used to be used for "trick" teaspoons that melted when you tried to stir your hot cuppa.

That didn't stop them then ;-)

Reply to
budgie

This isn't likely in a piezo device since the DC currents are very very small. There is nothing in the universe more magnetic per pound than a Ni plating.

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kensmith@rahul.net   forging knowledge
Reply to
Ken Smith

On Tue, 22 Mar 2005 07:50:37 -0800, John Larkin wrote in Msg.

All possible, but we've been using epoxy forever and never had had problems with it. Of course we try to not put the glue joints within direct sight of the sample surface.

Yes but it melts when you bake out the system at 150 degrees. And it makes terrible joints.

Yup.

Yup. That's me. And this is the reason why you develop superstitions and hate to do something that you haven't done before, even if by any rational argument it should be safe (like: If epoxy is OK, lead should be OK).

BTW the epoxies we use are those horrenduously expensive compounds from Epotek, not your home-depot two component glue. It's semiconductor industry stuff I believe.

No space.

--Daniel

Reply to
Daniel Haude

Or even "Let's heat it red-hot and pump it down for a week or so while hitting it with a hammer every couple of hours." :)

Reply to
Guy Macon

I read in sci.electronics.design that Ken Smith wrote (in ) about 'Lead-Free Solder: Weird Behavior', on Tue, 22 Mar 2005:

But what about the supplies to whatever is connected to the piezo?

I find that astonishing. Ni plating is more permeable than, say, Permalloy C, or has a higher coercivity than barium ferrite, or what?

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Regards, John Woodgate, OOO - Own Opinions Only.
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Reply to
John Woodgate

I read in sci.electronics.design that John Larkin wrote (in ) about 'Lead-Free Solder: Weird Behavior', on Tue, 22 Mar 2005:

Second only to gallium, I think, for difference between melting and boiling points:

Ga 29.8 and 2070 C In 156.6 and 2050 C

High boiling point implies low vapour pressure. Normally.

--
Regards, John Woodgate, OOO - Own Opinions Only.
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Reply to
John Woodgate

Perhaps dip the peizo into a solution of copper sulphate? CuSO4 plates most metals with copper.

Reply to
Mark Jones

Hmmm, piezo in UHV. Are you moving something a tiny distance, like for an AFM or an atom probe?

John

Reply to
John Larkin

On Tue, 22 Mar 2005 19:47:03 -0800, John Larkin wrote in Msg.

Yes, this is a piezoelectric stepper motor for an STM. I've built about a dozen of them, but this is the first time I use copper-plated piezos. The whole apparatus is described in Rev. Sci. Instrum. 75, 4871 (2004).

--Daniel

Reply to
Daniel Haude

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