Heat Xfer Compound Question

[lectriglide]

I am re-working a couple 200a esc's (Skywing & Himodel) and am wondering if the product linked below would be a good replacement for the thermal tape found between the FET's and water cooling plate.

Even with sanding, I am not getting total contact with all the FETS. Can someone with an electrical or engineering background decipher the specs and tell me if this stuff is any good or at least better than the tape.

I also have some arctic silver, but was told it would dry out and would also present conductivity problems. Unfortunately, I am totally lost on this kind of stuff.

http://www.mgchemicals.com/products/860.html?PHPSESSID=8843d0082d9ef2c049effb3a09ece813

[Jeff Wohlt]

arctic silver is one of the best out there. I just took tape off mine and will be using the silver. Just watch were the cooling plate goes up so it does not touch the leads if it moves. For this I am cutting a strip of the thermal pad and putting it over the bare leads. I also sprayed mine with spray electric tape...the clear version.

[Alexgar]

i have been considering this i used my last piece of tape i had from computer stuff, i am also trying to watercool a 200 amp cheapy

http://cgi.ebay.com/Thermal-Adhesive-Tape-3M-Heatsink-100x100mm-Square-New-/170484364864?pt=LH_DefaultDomain_0&hash=item27b1a8f640

[m4a1usr]

I am re-working a couple 200a esc's (Skywing & Himodel) and am wondering if the product linked below would be a good replacement for the thermal tape found between the FET's and water cooling plate.

Even with sanding, I am not getting total contact with all the FETS. Can someone with an electrical or engineering background decipher the specs and tell me if this stuff is any good or at least better than the tape.

I also have some arctic silver, but was told it would dry out and would also present conductivity problems. Unfortunately, I am totally lost on this kind of stuff.

http://www.mgchemicals.com/products/...effb3a09ece813

Be very carefull when you hear someone stating "Sand down the uneven irregularities in FET surface conditions" to allow for maximum conductive efficiencies. Thats misleading. The case design engineered into a FET is to allow for under load conditions to exist per that data . Thats assumed intact construction data at maximum load. Not some idea created by after thought "back yard engineering" to maximize btu transfer because his latest attempt suceeded. Testing by a factory design is what works in industry. Its the norm.

This grey area is where such misconceptions breeds exagerrations with no basis of industry accepted criteria. There is no chance I would "sand down" the casing of my ESC FET's to accept some media transfer method (and make it better!) and assume it works as per advertised. Your a smuck to make such an assumption! What shrimp boat did you just get off?

FET connstruction is assumed to be as efficient as possible when the design is left intact. Not when you take a grinder and render it to some other condition in question.

Thermaly conductive tape is an assumed risk, as is any media you assume makes the best contact for heat transfer. What I do know is the modification of a design renders it less then effective from the original.

John

[lectriglide]

There is no chance I would "sand down" the casing of my ESC FET's to accept some media transfer method (and make it better!) and assume it works as per advertised. Your a smuck to make such an assumption! What shrimp boat did you just get off?

John, thank you for your response. Due to my ignorance, I merely followed what many others have done to "back yard engineer" their Himodels and similar other inexpensive esc's. I was careful about only sanding what looks to be the conformal coating off the FETs, so my hope is that the actual FETS are undamaged.

I would appreciate your opinion on my "real" question regarding the effectiveness of the silicone thermal compound vs the tape, or even the arctic silver. I realize the tape has no defined specs, but you are obviously knowledgeable in this area. Thanks for your input!

[Jeff Wohlt]

All I know is only 7 fets out of 18 were touching the tape on mine. This is not good. The paste will fill it in better. I understand John's comments and certainly you do not want to sand too far. Mine also had the coating on them and when removed they were much better...only slightly sand the fets down.

I would say using a compound will take up more slop than a tape....mine proved it. Now with paste I will get good contact with all the fets. It did not take much to get them even...my sanding block was the cooling block with some paper wrapped around it.

[785boats]

Harsh words John.
Many backyard engineers have designed & built better pieces of equipment than the laboratory engineers.
Sanding a couple of thou off the fets doesn't affect their performance. But the increase in cooling does. In a positive way.
I've not had an ESC that I've modified blow yet .
lectraglide.
The type of thermal paste you are referring to is, in my opinion, the best type. It stays liquid up to 200C & transfers the heat better. If your ESC gets that hot you've got bigger issues than the type of heat transfer paste you use.
Because it stays liquid I always put a small drop of epoxy on the very corners of the corner fets to locate the plate so it won't move around & touch the wires. I also chamfer the edge of the plate nearest to the wires for more clearance
In the attached pic you can see only 4 light grey spots on the thermal tape of the cooling plate that came off one of the ESCs The rest of the FETS weren't touching at all. With the bottom ESC, you can see where I've filed off a couple of thou. The one on the right has not been filed.
Heat transfer paste works best as a thin smear between two metal surfaces touching each other. Not as a gap filler.

All the best.
Paul.

[lectriglide]

Like Jeff and Paul, one of the ESC's had 4 FETS in contact with the tape, the other had 6. I'm sure I took the time to take them apart before using them.
Paul - I will be sure to use a tiny drop of thermal epoxy on the 4 corner FETS to affix the plate. I didn't want to use it on the whole cooling plate in case I wanted to reuse it. The epoxy stuff works great, I used it to affix sandbar resistors to the case on some PC power supplies I converted.

[785boats]

The sad thing is, they are bringing these type of ESCs out now (HiModel, Mystery, Hobby King, Suppo, etc) with water cooling plates pre installed with the same tape & with the same gaps between the tape & the fets. I've had a mates apart & fixed it, because it was over heating relative to the load that was on it. So even a new watercooled ESC (of this type) needs to be fixed before its first run, if it's expected to last.
Cheers.
Paul

[NativePaul]

Thermal tape is rubbish, it comes in wildly varying specs for its thermal conductivity and price, if you want anything that is half decent you have to pay a fortune for it I needed some for another project and ended up paying £20/$30 for a 3"x6" strip that was up to the task at hand, and it was still vastly inferior to the worst thermal grease that I found or indeed thermal epoxy.

I use thermal epoxy each FET on my himodel type 200A ESCs, I don't sand them I rely on the gap filling properties of the epoxy safe in the knowledge that while having those gaps is far from ideal, even with the gaps there is better thermal transfer than the stock tape would have, even if they used tape that cost more than the ESC. I do see these ESCs as disposable and now pot the ESC itself rather than seal it in heat shrink leaving it serviceable as I do with my more expencive ESCs, but Heat transfer epoxy is considerably weaker than regular epoxy and you stand a good chance of getting it of without breaking something if you put it in the freezer overnight before removing it.

I also use thermal epoxy to glue 2 squished alloy tubes between the fins of the stock coolers to watercool them.

[n.h.schmidt]

Heat Transfer Glue

Hi
I have something to add to this. I have watercooled a couple of Hobbyking cheapo escs. I used this to glue the cooling plate to the fets and transfer the heat. Fujik Silicone Thermal Glue . Weekly Deals has it for $8.00 and Deals Extream has it for $7.23. It's non conductive and will not corrode anything like some silicone glues. Put a lot of it on the esc fets and place the cooling plate on the glue .Put some weight on the plate to squish out the excess and let dry.
I have been running a esc done up this way for two years no problems . I have also completely covered the esc with this stuff to add a degree of waterproofing to it ,no troubles
n.h.schmidt

[ray schrauwen]

Be very carefull when you hear someone stating "Sand down the uneven irregularities in FET surface conditions" to allow for maximum conductive efficiencies. Thats misleading. The case design engineered into a FET is to allow for under load conditions to exist per that data . Thats assumed intact construction data at maximum load. Not some idea created by after thought "back yard engineering" to maximize btu transfer because his latest attempt suceeded. Testing by a factory design is what works in industry. Its the norm.

This grey area is where such misconceptions breeds exagerrations with no basis of industry accepted criteria. There is no chance I would "sand down" the casing of my ESC FET's to accept some media transfer method (and make it better!) and assume it works as per advertised. Your a smuck to make such an assumption! What shrimp boat did you just get off?

FET connstruction is assumed to be as efficient as possible when the design is left intact. Not when you take a grinder and render it to some other condition in question.

Thermaly conductive tape is an assumed risk, as is any media you assume makes the best contact for heat transfer. What I do know is the modification of a design renders it less then effective from the original.

John

Nice post, I have destroyed aBOUT three 200 amp esc's because I oversanded the fets.

Now, I just rely on the Transfer compound.

Besides, cooling the top of the FET isn't right either as the metal lower portion gets hot first. It helps but, isn't the best solution.
If you look at a Swordfish 120 or 240Hv you will see they send water cooling to the bottom of the FETS where the heat is generated.

[ray schrauwen]

Hi
I have something to add to this. I have watercooled a couple of Hobbyking cheapo escs. I used this to glue the cooling plate to the fets and transfer the heat. Fujik Silicone Thermal Glue . Weekly Deals has it for $8.00 and Deals Extream has it for $7.23. It's non conductive and will not corrode anything like some silicone glues. Put a lot of it on the esc fets and place the cooling plate on the glue .Put some weight on the plate to squish out the excess and let dry.
I have been running a esc done up this way for two years no problems . I have also completely covered the esc with this stuff to add a degree of waterproofing to it ,no troubles
n.h.schmidt

I use it too Ned, works great! Toxic so wear gloves & wash up!

[m4a1usr]

Harsh words John

Hey, I appologize. My comments should have been worded more concisely. I am not knocking anyone. You have had success. That has worked for you. But I have tried the uniform surface assumption in heat conduction and payed the price. I cant afford to make mistakes like that. Not that I'm poor, but I have an issue with repeated attempts at "improvements". I cannot offer comment about unknown industry conductive heat foam tape but I use and endorse the 3M tapes. They work well. Much better then heat sink compounds in my applications. Been down that road and not ever going back.

Will they perform as well in yours? I dont know. First off, I dont ask a 200 amp speedo to operate at 200 amp spikes, much less 150 amps constant. Thats too close in my guesstimate. I leave a minimum of 1/3 over all capacity in excess. So my 180 speedos never run over 120 constant. At least in setups running more then 60 seconds. Now in my SAW builds I push the limit well beyond. Sorry if the comments appear decisive but its just my opinion and experience. Take it or leave it.


John

[AlanN]

Do a search for loctite 384. Mcmaster used to sell it but I see it is not on their site now. I have used it without any issues. After applying the adhesive I would just shrink wrap the controller and heat sink and leave it for a day.