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Copper Sheet Thermal Resistance

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dknguyen

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Does anyone know where to find, or how to get the thermal resistance of a flat sheet of copper or aluminum of X thickness to ambient? Even a single ball-park number woudl help me out a lot.
 
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The problem I have is I don't know what the C/W-m unit means so I can't adapt it for my sheet. ANd I haven't been able to find an explanation either.

And I need it for the sheet metal to ambient, not between two ends of an object.

EDIT:
But from what I just read, the number is the thermal resistance between two opposite faces of a 1m cube of the material. SO using my really crude understanding, and dividing down the cube's dimensions into my sheet of metal (and an equally sized sheet of air with which it is in contact) it would seem that the conductivity of the metal is so much better than the air it plays negible role in the result. So the total thermal resistance is almost entirely dependent on the amount of air in contact with the metal rather than the conductivity of the metal itself (probably because the metal is so thin so heat doesn't have to travel very far in it unlike a larger heatsink). It seems it works out to be 16C. But that doesn't seem right since a 1x1" 2 oz copper PCB has a thermal resistance of 45C to ambient.

The assumption of a 1mm sheet of air (equal to the thickness of the copper) is also baseless.
 
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Well I finally found heatsinks of a suitable thermal resistance that are light enough to fit on the heli, so I don't need all this anymore. THanks everybody.
 
Heli? as in helicopter?
 
Make a video when you have it working. Sounds neat :)
 
Im kind of hoping it gets off the ground at all. It seems it's going to be a bit heavy since I opted for the smaller model since it's parts are machined better and more single-piece parts.

But with this last problem solved it seems I can make an ESC for the thing with the minimal number of FETs. Now it's all up the parasitics...
 
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I love making scale models. I designed, machined and built a RC dragster awhile back.
Here was my 3D model
**broken link removed**
And the final product.

**broken link removed**

The Nitro pack was less than spectacular, so I ended up putting some of those model rockets in place of the Nitro engine. The outcome was that the car went so fast the thing fell apart..lol I have video, but the file is like 150 meg, and I don't know how to shrink it to a size for the net.

Oh and sorry, I did not mean to detract from the subject of your post...
 
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lol. "My engines weren't good enough so, naturally, I replaced them with rockets. Unfortunately, the they did not perform as anticopated."

If I do larger I will probably go nitro, but I don't want to deal with the maintainence and learning curve right now. Because I love electric because I'm an EE, and hate electric because it's noisy, messy, and fussy.
 
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Rockets on a chopper? lol. Your kidding right?
 
Remember Don't let drunk friends design. :)
And that was a joke...
 
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If you are both drunk, might I suggest protective gear :)
 
Did you ever solve your snubber dilemma? That was a tricky one?
 
Did you ever solve your snubber dilemma? That was a tricky one?

I am using extenral (non_pcb mounted ) FETs now, so I can swa out whantever snubbers I Feel like indepent of the PCB. RIght now I am just going to go with thte best resistors and capacitors I can find, and see how that work sout,. This is for the RC snubbers snubbing across each BLDC terminal. I am now going to rely on the avalanche and internal diode of the MOSFETs since it is not pratical to place a MOSFET in parallel with eveyr single MOSFET mudle module. It seems that the MOSFETs avalanche energy can dela with em maximum wire indutance that will be encountered anyawys, as long as I can handle all the motor iinductance in the snubbers.

Camn yo tell Im a bit tipsy right now> thats hwy i always check over my designs against the next mornig.

"EDIT : im sugins external mosfets so to get around the ridiuclous costs of miult-layered pcbs since I can t seem to find an efficient way to wire all the gates and powr traces on jus two pcvbs. its also just cool to use MOSFet modules since tou just need ring eterminals and cn swap them out whenver tyouw an t. it also makes it scalable tsince I just need a logic+gate driver PCB. If i ever need a larger controller that is still within the limits of the gate driver, I just need to parallel more MOSFET modukes. im baiscally turning the heli chassis into a heatsink for the MNOSFETs.
 
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I just got back from Dave and Busters, So I know what ya mean. I had a summer school chem exam today, and boy am I feeling soluted...lol
 
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