127 microns? Wow. I think.

I may be talking nonsense here, having dealt with piezo cells only in the context of them being mounted in plastic / rubber boots of sorts and where the connections were made via wires. But I wonder in your case if an electrically conductive nickel or silver based epoxy would do the trick? I've also played with some electricaly conductive RTV which might do the trick from a "not too brittle" aspect.

Epoxy was our first choice but the thickness of the bond became a problem. Once you fill enough material to make the epoxy conductive you have a rather stiff mixture that doesn't spread well. At least not by any method we've tried.

Oh. I see. Well shucks.

Er...conductive tape? Something like:

http://www.tedpella.com/SEMadhes.htm

At least for the spots where you need conductivity. Maybe in conjuction with a blob of non-conductive epoxy elsewhere for strength?

Not recommending that company's products, btw. They're just the first example Google coughed up.

Is that 127 microns in X, Y, And Z?

Ceramic can handle solder temperatures. You could put a really thin copper plating on the stainless, and possibly on the nickel as well, so solder would adhere. In a clean environment with the right amount of solder, pressure could reduce the solder to a very thin film.

There are conductive epoxies that are filled with flakes of silver. These epoxies are highly conductive and yet have fairly low viscosity. They can be applied by silk screening, or doctor blade, to achieve a thin, consistant bond line. Solder is another option depending on the temperature limitation of your PZT. This will require pretinning the stainless steel using an acid flux and carefully removing all traces of acid prior to the final soldering process. Soldering PZT is not fun, but yields the most reliable joint, if properly done.

Soldering PZT is a problem, your temperature (currie temps) are rather low. Some PZT have upper temp limits as low as 70'C (40'C from the currie point).

Now, Ni is a very difficult surface to bond to directly.

I suggest that you have 5 u" of Au or Pd then use a silver die attach epoxied or a silicone silver fill film (3M and others).

If you do not need conductivity then use master bond FL30 or Hysol 902 or 942 materials. Both will work.

But with PZT you really don't need heigh conductivity as you are only accuating the PZT with an electric field not by injection electrons.

We use 7% silver load in the adhesives (will not tell you this) to do what you are asking to do.

Good luck.

Also, you may consider using coupling agents on the nickel surface.

hello, maybe spot contact weld? or laser welder like used in jewelry repair/manf.

metalSmith's

Because your piezo crystal already has a conductive surface electrode, you do not need to provide continuous conductive attachment. You need only provide local attachment of a small conductive foil or wire to the bonded side for electrical contact. The remaining surface can be adhered with any kind of adhesive that is optimized for mechanical properties. The electrical attachment point can extend through a hole or groove in the stainless steel substrate.