Was that 8 millimeters? I've never heard of anyone making a bridge that
long. If that's the case, you're probably going to have to try to figure
it out from a material mechanics viewpoint. Assuming you're making a
bridge, you can approximate this with a cantilever beam with a bending
moment at the tip, to make it half of a span (there's also a stretching
component). I'm not sure what downforce you would want to use, so I would
probably start with the maximum force it could take without snapping. Of
course you'll still need to know how far it can deflect (the sacrificial
thickness), and the width of the beam.

THis is just a starting point. I think I've seen this modeled out before,
but I can't remember where. It's probably in Kovacs ro Trimmer.

Hope this helps,

Jesse Fowler
  UCLA/MAE Dept., 420 Westwood Plaza, Room 37-129, ENGR IV
  Los Angeles, CA 90095-1597 | (310)825-3977
"Never worry again about the quality of your random numbers!"
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On Mon, 4 Nov 2002, Michael D Martin wrote:

> Hi,
>   Does anyone know whether it is possible to produce low stress nitride
> films that are a micron thick or thicker? If so, where can I get them?
>   a related question ...
>   How thick of a silicon nitride film would be required to span 8mm
> after release?
>
> Thanks in advance,
>           Mike Martin
>
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