Let me see if I can make sense of it...
The copper, i believe, is going to build up in temperature, throughout the distance between the heater and the top of the heat die. The minimum temperature will be that of the cooling solution, as it deals with the wattage. The maximum temperature...
Ok, I think you're right: it's not going to make a difference, other than the heater cartridge getting to a rather high temperature. Watts are Watts...
Let's say I'm looking at 1 inch (25 mm, for the sake of argument) between the top of the die, and the heater:
Q=-k*A*dT/L
Q=let's say 75 Watts
k=400W/m*°K
A=0.0001m^2 (10 mm by 10 mm)
L=0.025m
dT=?
75=400*0.0001*X/0.025
I can resolve X to: 46.9 deg C, which is above the cooling solution temp (plus baseplate, plus TIM joint), so maybe 80 deg C.
As long as the cartridge can take 80 deg C, while outputting 75 Watts, it should be ok, right?
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