Reply to: RE>Mechanical properties of Si chips.

> We have put our bulk micromachined silicon chips in a plastic
> package. Some of the chips breaks or we can  se fine cracks, usually
> close to the v-grooves. There is a bonded glass lid on top of the
> v-grooves that should strengthen the device. The chips also had been
> edge polished after dicing with 3 microns and 0.3 micron papers.  Do
> anyone know if the polishing itself can lower the mechanical strength
> of the chips? Or is the dicing bad enough?
There is a good paper by Ericson and Schweitz (from Sweden) on the
micromechanical fracture strength of silicon. They fractured silicon cantilever
beams with a micromanipulator. From their abstract, "Diamond polishing was
found to decrease the fracture strength drastically, but polishing followed by
oxidization not only restored the original strength, but actually increased it"

Ericson and Schweitz, "Micromechanical Fracture Strength of Silicon," Journal
of Applied Physics, Vol 68 (1990) 5840.

Hope that helps.

Peter Krulevitch
krul@llnl.gov