at issue is the bp flatness, for wbs or hsfs - same issue
since the bp 'mates' against the die, a starting point in the evaluation is the assessment of the die flatness:
concave ? convex ? flat ? what kind of ranges ?
irregular topography ? (look at the P3 above !)
THEN one looks at the effect of different flatnesses on the die temp
(everything else being QUITE controlled of course)
and from this one can hopefully conclude how much flatness 'makes sense'
- no point in chasing 2A° if the discernable effect threshold is 10A°
(for instance)
just learning more about what we are trying to do
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