Lead-Free Solder: Weird Behavior

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 ;-)

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.

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

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." :)

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?

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.

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

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

John

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