>>>>>>>>>>>>>>>
David Wood wrote:

  Have you tried pulling wafers apart? If so do you have any results,=20
  numbers, etc?

<<<<<<<<<<<<<<<
Several people have tried to pull wafers apart. See for instant:

J. Electrochem. Soc. vol. 141, no. 11 Nov. 1994, p. 3225-3230, where values up
to 4 MPa is reported (values of torsion and shear are also reported) or

J. Appl. Phys. 60(8) Oct. 1986, p. 2987-2989, where fracture strengths of
100-200 kg/cm2 is reported.

Several more references can be found in these papers.

The low values are normally explained by the formation of microvoids, that
reduces the effective bonding area, see for instant:

Proc. of the First Int=B4l Symposium on Semiconductor Wafer Bonding, p.
102-111.

Hope to help

Ole Sondergard
Danfoss A/S
DK-6430 Nordborg
Denmark