Heatsinks and Thermal Epoxy - ideas? - RC-Monster Forums

10kman · **Heatsinks and Thermal Epoxy - ideas? -** 06.05.2007, 12:50 PM

I am trying to get an idea together for a nice heatsink for my Quark 125, and was wondering about a few things.

Is there any other way to fix the Quark to a heatsink, other than thermal epoxy? Something solid, but something that if I do have an issue, I can remove it and get it serviced without getting scolded by Quark (if they would, I'm not sure, but just wondering).

I couldn't think of anything good unless I made like a complete cradle for the ESC, then just strapped it down, but even then it can move.

Also, can a heatsink be too large? Other than the fact that it just takes up too much room, is there a point of no return?

Gracias......

10k

BrianG · 06.05.2007, 01:00 PM

Well, you have a few options:

You could use regular thermal compound and find a way to secure the case to the heatsink so there is absolutely no movement whatsoever. Movement between the two will drastically reduce the effectiveness of the compound.
Use thermal pads. This is not as good as thermal compound or epoxy, but better than nothing. And it should provide a good enough bond to keep the heatsink in place, although I'd also ziptie it down just to be certain.
Use thermal epoxy. This IS removeable. All you have to do is put the heatsink and ESC in the freezer for about 20 minutes and then gently pry the two metals apart. It will pop off - I've done it several times. Some say a heatgun will work too, but I haven't tried that.

A heatsink cannot be too large. At some point, it won't help much, but it won't hurt either.

10kman · 06.05.2007, 01:13 PM

Yeah I just read that the Arctic Silver stuff will freeze (crystalize), and pop right off, so that's not a big deal.

I'll get to designing my heatsink. Working with metals is tough for a guy in an apartment. I have tools and such, but I need real stuff for these projects!

Aluminum is better than copper for heat right? I'm trying to remember my physics......

BrianG · 06.05.2007, 01:16 PM

Copper is actually better, but heavier and not as easy to work with IMO.

06.05.2007, 02:18 PM

You don't need to design anything elaborate. Cooling fins, which simply add surface area for air to come into contact with are only necessary if the sink is only using air to dissipate heat. My chosen method is to just use a piece of 1/4" aluminum plate as a heatsink to act as temporary storage to quickly draw heat away from the esc, but have this sink channel the heat to the chassis. While I was running my Quark with this setup, the esc never got over 150. I went this route because I detest fans and will only use them when absolutely necessary.

BrianG · 06.05.2007, 03:22 PM

^ +1. That's what I do as well. The Quark gets warm, but it's not like it is dissipating hundreds of watts. It's just a matter of adding thermal mass (1/8+ thick plate) and then using fins to dissipate the heat.

Serum · 06.05.2007, 03:30 PM

And if you must add a heatsink, look at the Zalman ZM-NB32K two of them would do.

I was thinking about picking two up..

06.05.2007, 03:32 PM

That thing looks TALL. It also looks like it would work very well without any fans too.

wallot · 06.05.2007, 03:36 PM

The zalman is not bad (used to use them, but they are not wide enough) but Artic silencer works much better after cuting extra copper plate (the finned part is just bit bigger than quark)

I used just bit of thermal epoxy (around edges) and rest is artic ceramique

Serum · 06.05.2007, 03:51 PM

they are 37X37X32mm (wxdxh)

the fets aren't sitting too for to the edge? the zalman is made smaller on the bottom, but it can transfer the heat, i am pretty sure of that.

wallot · 06.05.2007, 04:33 PM

yes it works ok but I just did not like the fact that part of the quark was not sitting on the heatsink

zeropointbug · 06.05.2007, 04:59 PM

I agree, you don't need ALL surface to be covered, just where the FET's are. Making contact on the entire bottom will make minimal temp decrease.

But... I do like the size of the Silencer, as I was going to use it myself until I got my truck built and had no room between my batts.

I found a couple other heat sinks, I am going to try them out.

10kman · 06.05.2007, 05:03 PM

Which side(s) of the Quark am I concerned with most for cooling, the bottom and the side with the servo wire, or the side with the motor input plugs?

I have some time before my new LiPo's get here, out of stock surprise email came my way after inquiring. I also don't want to use a fan, I will try to cut a hole or two in the body of the truck to allow some air while moving.

jhautz · 06.05.2007, 05:08 PM

Quote:

Originally Posted by 10kman

Which side(s) of the Quark am I concerned with most for cooling, the bottom and the side with the servo wire, or the side with the motor input plugs?

I have some time before my new LiPo's get here, out of stock surprise email came my way after inquiring. I also don't want to use a fan, I will try to cut a hole or two in the body of the truck to allow some air while moving.

The Bottom is where the fets are.

zeropointbug · 06.05.2007, 06:10 PM

I found a couple more heatsinks laying around last night. Just thought I would post them.

The two angle ones are from a PC power supply, and the other one is from an old CPU (Pentium III ?). The one that the case is sitting on... it's like it was MADE for the Quark, it fits perfect.

I just going to play around with these and see what kind of performance I can get from these, before I make the custom Quark case.