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Best thermal pathway for heatsinks

ryansoh3

ryansoh3

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Hi LPF, I was thinking of designing a heatsink and came upon a question.

I'm using 9mm diodes in a threaded module. Is it better to:

Use only the copper module and have the back of the diode contact the heatsink. This will leave an air gap where the module is threaded:

13347286664_c041fd807c_n.jpg


Use the aluminum back, but the back of the diode will not be heatsunk.

13347286914_c4883904ec_n.jpg


Would love to hear your guys' thoughts. :)
 





I've always believe that the drive casing should be present, because without it, there's an air gap where the threads are right next to back of the diode. I had hoped that some of the modules would be made solid, with no threading, but so far nobody has made them.

Still, if you can manufacture the first option with sufficient thermal contact, it might be a good way to go too.

A better solution might be to get some of the modules from Rick Trent that have the drive case made of copper too.
 
Great, thanks for your input.

I have an uneasy feeling about the back of the diode not touching anything in option two. Seems like a waste not to heatsink the flat part.
 
Whoops, didn't realize DTR was selling them, or else I would have happily gotten those. Wish they were copper though, haha. Thanks for the info!

Couldn't rep you, sorry!

Edit: Are the modules on his website? Can't seem to find them...
 
Last edited:
this helps me too. I think I will have to get one of those from DTR. too bad they are not copper, but rick trent's would not fit in the heatsink I have without being shortened. An Aluminum is much better than nothing, and then no air gap, as B-B pointed out
 
ryansoh3 said:
Whoops, didn't realize DTR was selling them, or else I would have happily gotten those. Wish they were copper though, haha. Thanks for the info!

Couldn't rep you, sorry!

Edit: Are the modules on his website? Can't seem to find them...
Click to expand...

I don't really know. I just ordered a 9mm diode and got this. Maybe you can simply purchase the 9mm diode with module and send him a message that this is what you want.
 
Maybe you can kill two birds with one stone. In lieu of a copper driver casing -- which I've only seen Rick Trent carry -- something else you could try is connecting the back of one copper module to the other:

attachment.php


You can use thermal adhesive/grease to make a better contact. Also, most of those brass driver cases have enough threading that if you were to chop off the back, you could use the threaded section to connect the two modules like this:

attachment.php


All it would cost you is a second copper module, a brass casing, and some sort of cutting tool. It'd be much better if the brass threading were made of copper or something better, but it is still better than just air, and would mechanically hold the two modules snug against each other in addition to the thermal grease.
 

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look at this one the back of diode will touch the 2 part copper heat sink
eBay item number: 321238757565
 
I wish a copper module casing was the standard.
¡Viva la Revolución de Copper!
 
@ B-B

for your suggestion, would not one of the modules need to be for a smaller size diode? otherwise, it would not contact the back of the diode right? lets say a 9mm diode is used. would the second module need to be a 5.6mm, or could a 3.8mm work too?
 
Anyone know what the rear thread pitch of standard Aixiz modules is? We should make a better back.
 
Shakenawake said:
@ B-B

for your suggestion, would not one of the modules need to be for a smaller size diode? otherwise, it would not contact the back of the diode right? lets say a 9mm diode is used. would the second module need to be a 5.6mm, or could a 3.8mm work too?
Click to expand...

I'd probably just keep it the same size unless you could be sure that the 3.8mm hole wouldn't cause any shorts with the pins in the back. I'm not sure if the smaller hole would make any different either because the diodes are usually pressed below the edge of the hole in the back, leaving a small gap.

rhd said:
Anyone know what the rear thread pitch of standard Aixiz modules is? We should make a better back.
Click to expand...

I think Mohrenberg might know, since he had a GB for some of these to be manufactured. We could use the opportunity to create more solid copper backs too, not just the thin-walled variety like the current brass backs.
 
Bionic:
That was my thinking also.

I know that the back thread info actually exists in a post on LPF somewhere - I've seen it before - but it seems to be resistant to searches.
 
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