Dear Bob,
Thanks for the suggestions. The bond I'm looking for is thin, say 5um or less,
electrically conductive and with a low damping of mechanical vibrations and, of
course with a high shear strength. Difficult at low temps, I reckon.
Indium Gallium soldering with evapourated layers may be possible, hopefully
with vacuum to bond the specimens. These alloys aren't very stiff though, but
Inidium does wet well which is very important in my limited experience.
Other methods I hope to try include the AuSn eutectics and AuSi would be
excellent if the PZT can be poled after bonding ( there is a shape change
however). Anodic bonding is also worth a try and I've got some info suggesting
300-400degC and 1000V for a Si glass bond.
Glass frits and other non conductors don't appear to have great advantages over
epoxies/phenolics.
Indium Corp has an office near us so I shall have to try the wetting by Indium
alloys in the next few months.
Any articles on bonding you have would be very much appreciated and many
thanks for your interest too.

Phil Rayner
Cranfield University

From:                   "bob lyness" 
To:                     "Phil Rayner" 
Subject:                Re: Bonding bulk PZT to Silicon/Other
Date sent:              Thu, 5 Nov 1998 18:12:20 -0500

> The ideas I had in mind don't fulfill your need to maintain the bond
> temperature below 200degC for short times. I was thinking of doing a AuSi
> eutectic bond by scrubbing, but this requires temperature well in excess of
> 370degC for short time. Another idea was to sputter a few microns of
> AuSn::80:20 alloy which melts at 280degC and is solderable.
> Perhaps you can investigate indium based solders, which are low melting and
> could be fabricated as a foil, or possibly sputtered, but in the latter case
> you might have to worry about shelf life (contact Indium Corporation of
> America, based in New Jersey, I think).  I could find exact address.
> I have also seen articles in the IEEE microelectronics magazine which
> detailed a couple of materials which bonded at a sub-eutectic, but here the
> constituents had to be quantitatively controlled to a great degree.  It
> seemed like an immature but interesting process.  I could send photocopies
> of the articles if you wish.
> Can your material be anodically bonded?  I don't know the temperature
> requirement.
> Could you use an insulating substrate like ceramic or glass?
> What properties does the bond require electrically and mechanically.  Could
> you spin on a layer of polyimide or glass  frit and then cure?
> Probably too many questions,  Good luck.
>
> -----Original Message-----
> From: Phil Rayner 
> To: bob lyness 
> Cc: [email protected] 
> Date: Thursday, November 05, 1998 9:32 AM
> Subject: Re: Bonding bulk PZT to Silicon/Other
>
>
> The temperature and time depends on the curie temperature of the
> material to keep the material in a poled condition. For the PZT I
> would use this is about 300degC to completely depole. Significant
> depoling can occur at say Tcurie/2 about 170degC if the time is
> more than 30 mins (say). I have not actually tested this yet
> however.
> Another problem is that exceeding that temperature can easily
> generate cracks just under the surface due to local stresses and
> crack growth in the ceramic.
> All in all the temperature is best kept under 200degC and
> preferably under 150degC for less than 1 hour. Alternatively, poling
> a bonded material may be worth investigating.
>
> Phil Rayner
>
>
> On 4 Nov 98, at 11:50, bob lyness wrote:
>
> From:           "bob lyness" 
> To:             "Phil Rayner" ,
> 
> Subject:        Re: Bonding bulk PZT to Silicon/Other
> Date sent:      Wed, 4 Nov 1998 11:50:46 -0500
>
> > What temperature and time can the PZT withstand?
> >
> >
> > -----Original Message-----
> > From: Phil Rayner 
> > To: [email protected] 
> > Date: Saturday, October 17, 1998 3:46 PM
> > Subject: Bonding bulk PZT to Silicon/Other
> >
> >
> > >Hello everybody,
> > >
> > >I'm building a piezo micro motor, and I'm looking for methods of bonding
> > bulk
> > >PZT to a stainless steel or silicon substrate.
> > >These can then be lapped/ precision ground down to required thickness
> (30um
> > >or so), giving much better propeties than thin or thick film PZTs, which
> we
> > also
> > >do here.
> > >Does anybody have any experience of bonding wafers with gold-silicon (or
> > >another type of) diffusion bonding, sputtering solder layers down or
> using
> > a sol-
> > >gel intermediate layer.
> > >Really, I'm looking for a way to avoid epoxy bonding (which could end up
> > giving
> > >a bond as thick as the PZT), so all ideas will be very much appreciated.
> > >
> > >Thanking you in advance
> > >
> > >Phil Rayner
> > >
> >
> >
> >
>
>
>
>
>