This question is related to thermal relief or heat transfer between the devices. So lets look at some specs.
#1: ISOTOP - Pd:
Total Power Dissipation @ T C = 25°C: 500W
Linear Derating Factor: 4 W/°C
#2: TO-264 - Pd:
Total Power Dissipation @ T C = 25°C: 520W
Linear Derating Factor: 4.16 W/°C
If adequate cooling is in place for both, would there be any difference in heat dissipation for these devices.
#1: ISOTOP - Pd:
Total Power Dissipation @ T C = 25°C: 500W
Linear Derating Factor: 4 W/°C
#2: TO-264 - Pd:
Total Power Dissipation @ T C = 25°C: 520W
Linear Derating Factor: 4.16 W/°C
If adequate cooling is in place for both, would there be any difference in heat dissipation for these devices.
The TO-264’s case-to-sink thermal resistance would be unavoidably higher. But the screw terminal package has a whole lot higher inductance, so in practice the switching losses would be higher at a given frequency, generating more heat to get rid of. You would have to fully analyze your system to determine which would actually run cooler. Sometimes a pair or more of TO-220s in parallel will beat a TO-264.
Thanks for the answer. How does one check stuff like that. Are there any documentations or does it come from experience ?
A lot of very high power IGBTs and Mosfets give case to sink Rth in addition to junction to case. That’s for a perfect greased interface - as good as it could possibly get. To that you have to add the contribution from whatever thermal interface material you use. That will be given in W/m-K and you calculate based on thickness and size. If you do use an insulator it adds a lot at high power levels. The bigger the mounting surface the less it hurts you.
Between devices? Or between a device(s) and the room?
4 W/°C is also 0.25 °C/W. Almost any "practical" heatsink has thermal resistance so much higher that 4.0 or 4.2 vanishes in the haze.
Heatsink should be appropriate for the device. Not a tin fin for a 1000W amp or a truck radiator for a headphone amp. Let's try a sink with thermal resistance similar to the device. For 0.22 to 0.3C/W I see prices from $50 to $427, and the $50 is for distributed input not one HOT part in the center. I don't know what a TO-264 costs but it is very likely that two devices at half the Watts each can use a cheaper cooling solution and be lower total expense.
Bad wording from my side. The original question was concerning the heat (or energy) transfer between the MOSFET case to the heat sink and if the TO-267 was considered inferiour SOT-227 "ISOTOP".
Used an online calculator to find the Heat Sink Thermal Resistance using the SOT-227 size (25x38mm), 500W device and with Panasonic EYG Series, 1950 W/m.K, Graphite Sheet
50 °C =0.04995 °C/W
80 °C = 0.11 °C/W
100 °C = 0.15 °C/W
125 °C = 0.2 °C/W
Calculator: Heat Sink Thermal Resistance Calculator
Used an online calculator to find the Heat Sink Thermal Resistance using the SOT-227 size (25x38mm), 500W device and with Panasonic EYG Series, 1950 W/m.K, Graphite Sheet
50 °C =0.04995 °C/W
80 °C = 0.11 °C/W
100 °C = 0.15 °C/W
125 °C = 0.2 °C/W
Calculator: Heat Sink Thermal Resistance Calculator
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