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SOT-227(ISOTOP) vs TO-264 heat dissipation

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tooki:

--- Quote from: coppercone2 on March 23, 2024, 02:08:00 am ---a lug is the copper crimp you put on a bolt

--- End quote ---
Crimped or soldered, both are common (though solder lugs are definitely far less common these days).

Fauks:
Here is a little mockup render to show what I am trying to accomplish.

The mounting holes are standard AMD AM5 socket heatsink mounting. The thermal pad under the MOSFETs is 3mm thick which brings the heatsink plate to the same height that a AM5 mounted CPU cooler would sit. So the top case side would get some cooling through the thermal pad and the top heat sink plate would get cooling from the tower cooler. It's pretty easy to find coolers that can handle ~280w continuous and for short bursts much higher. 

Solder pads for source/drain would be a few mm away from the terminals so keep trace length as short as possible. The PCB would be slightly larger to accommodate mounting holes for some sort of case. Maybe a mini ITX computer case? Also would house a separate small control board. 

I've also attached a mock up of how I was thinking of using the modules, and also how the heatsink would mount.

Thoughts?

T3sl4co1l:
I think you'll be disappointed using thru-hole parts with an aluminum PCB... check the specs from the fab carefully.  Isolated thru-holes will cost extra, or you need to find someone that does it.

I'd be fine with a brace cut from hardware store metal stock.

Tim

Fauks:

--- Quote from: T3sl4co1l on March 23, 2024, 07:37:33 pm ---I think you'll be disappointed using thru-hole parts with an aluminum PCB... check the specs from the fab carefully.  Isolated thru-holes will cost extra, or you need to find someone that does it.

I'd be fine with a brace cut from hardware store metal stock.

Tim

--- End quote ---

I didn't even think about that. I guess FR4 would be fine. The heatsink I have in mind has a pretty solid steel back plate to brace the board for the sink. Maybe use 2oz copper as well.

tszaboo:

--- Quote from: Fauks on March 22, 2024, 05:35:14 pm ---I'm working on making an electronic load and have narrowed it down to using a linear MOSFET in a SOT-227 module or a TO-264 package.

I would assume the module has better heat dissipation with better connections for thick wires vs using PCB traces. But according to the two data sheets (IXTK200N10L2, IXTN200N10L2) the TO-265 is rated a bit higher and also a bit cheaper. 

SOT-227 module:
SOA = VDS:100V, ID:5A, TC:75°C , tp:5s, 500W

TO-264:
SOA = VDS:100V, ID:6.25A, TC:75°C, tp:5s, 625W

Anyone with experience with these two packages? I'm still leaning toward the SOT-227 but I thought I would ask first.

Thank you!

--- End quote ---
You add together the Rthjc and Rthcs values, whichever is lower will handle more power. How much? Not 500W, that only applies to the magical world of room temperature infinite heatsinks and junctions at their rated max tempertaure. Not surprisingly the SOT227 is better. SOT227 will be better than anything other than those exotic MOSFET modules with gigantic packages. Even if the datasheet will tell you otherwise, it's just a much more solid way of mounting the part on a heatsink, with more clamping force and better heat transfer.

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