Hello! I am looking for a heat sink compatible with the 243NQ100R-1 rectifier. I’ve tried a few avenues of looking for heat sinks compatible with the 1/4" stud on the top to limited success. I’ve attempted using “half pak”, “d pack”, “TO-240” (for mounted heat sinks), among others as a wildcard to narrow my search. At this point, I am just hoping to find a heat sink with a 1/4" through hole. Unfortunately, SMC does not provide options for heatsinks on the datasheet either.
I’d be very grateful for whatever help people might be able to provide in this - thank you kindly!
Note: The one option I have found that seems to be acceptable is the Wakefield-Thermal 401A but I find it suspicious that only very few components match these requirements. Anyways, thanks again!
@michael.220
I too am not seeing that these have a specific heatsink that is to be used. From what I have found it looks like the recommendation can be the below.
From a Vishay product.
The contact surface of the heatsink must be flat, with a recommended tolerance of < 0.03 mm (< 1.18 mils) and a levelling depth
(surface roughness) of < 0.02 mm (< 0.79 mils), according to DIN/ISO 1302. In general, a milled or machined surface is
satisfactory if prepared with tools in good working condition. The heat sink mounting surface must be clean, with no dirt,
corrosion, or surface oxides. It is very important to keep the mounting surface free from particles exceeding 0.05 mm (2 mils) in
thickness
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Greetings,
The expected thermal transfer path is through the base of the part, not so much the screw.
Off-the-shelf heat sinks for such items are not especially common; designs using such items vary substantially, so there’s little sense buying up heatsink stock and carving it up in the hopes that the pattern chosen will just happen to match somebody else’s needs…
If you’ve got a spot in your chassis that’s electrically and thermally suitable, use it. Otherwise the likely route is to look for extrusion stock in a profile that can be mechanically and electrically integrated without too much hassle, and either put holes where they need to be yourself or have the extrusion supplier do so. Subject to MOQs & setup fees most suppliers of such materials offer custom mods, which DK can facilitate.
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Thank you Rick! I suspected something like this might be true. In this case, since the base plate is also a device terminal, I’m assuming a suitable location to mound this device would be one that’s electrically insulative and also has a bunch of thermal mass? Otherwise, connecting the high side to chassis would energize the entire chassis I’m assuming.
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I don’t where things fit into your system schematic or if the node(s) corresponding to the base would be OK to bond to the chassis. In the likely event that doing so 'aint OK, a person’s going to be looking to put electrical insulation somewhere. That might involve an insulating shoulder washer, some sort of thermal interface material with an insulation barrier (plain grease 'aint so good at blocking electrons…), plastic screws… There are options, and precisely what you’d want to choose depends on your specific needs for creepage, clearance, HIPOT, whatever. Then of course there’s mechanical questions such as vibration tolerance, thermal cycling, being able to keep up with thermal load, etc.
On the latter point, it 'aint thermal mass one’s concerned with so much as ability to get heat out of the system. Mass is at best a buffer against short-term variability; if you’re burning 100W inside the box and only 50 can get out, it’s simply a matter of time until things get crispy. To the extent feasible lighter us usually better, owing to other mechanical concerns such as vibration and impact tolerance.
Understood haha - makes total sense. Thanks for your insight Rick. This is a legacy component that might need to be swapped if cooling it is more trouble than it’s worth. A quick search gives me stuff like the VS-T85HFL100S05 which has an isolated base that I might look into instead. Thank you kindly!
