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Middlesex Industries strongly believes in 300mm PRIME and factory efficiency !
To plot an exact OC (operating characteristic) curve for the live factory
is impractical, because it involves measuring cycle time at many values
of throughput (wafer starts at steady state). However, a fair model of
the process can be simulated by knowing the tool layout, tool process
times and the process sequencing for all products. Then, running the
model with various WIP transport infra structures and dispatching,
different OC curves are plotted.
To evaluate the effect of the WIP logistics (transport + dispatch) on
the OC, the model does not need be overly exact. Varying only the
logistics will show its effect on the OC unequivocally. This is the only
true metric for comparing AMHS.
Ultimately, the best AMHS is the one which has capacity to handle the
naturally occurring dynamic upsets of the fab at the smallest practical
WIP lot size. The AMHS has big improvement capability for the OC.
This is the lesson for 300mm prime fabs.
Make sure you grab at the next SEMICON trade show one of these attractive promotional gadgets Middlesex made !
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