How to choose the right thermal pad/paste

Hello everyone,

I would like to use a heatsink for my brushless controller mosfets ( Link ),

And it's kind of confusing to choose the right thermal-pads and/or thermal-paste, I don't know which one of them is suitable for my need.

I would appreciate your helps.

Thanks

What have you looked at so far?

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Thermal pads thickness, which apparently don't dissipate heat as much as the thinner ones and the their heat sink need screws to hold in position, and the thermal-paste which seems to stick to the heatsink.

But since I am using the driver in the fully vibrating surfaces, I don't know which one of them would be a good option.
and for the 36V-15A which one of them can do the job?

BTW, this is my first time using heat sink, sorry if I'm making any mistakes.

I would use thermal paste, with a clip, or screw mount, ideally you want to threadlock the screw if you can.

Are you referring to MOSFETs on the board you linked to? Are you adding a heat sink to the ones on the board or removing them to a separate heat sink?
Paul

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I am referring to the MOSFETs on the board, I would like to add heat sink to those MOSFETs.

something like this:

heatsink

That seems to be a waste, as you will not be able to add individual screws to each MOSFET for attachment to the heat sink.
Would be easier to provide better air circulation to the MOSFETS if you can return them to upright position. Individual hear sinks might then be possible.
Paul

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I appreciate your help.

Since this driver is about to be put in the dust and dirt situation, what is your opinion about this:

Putting a huge heat sink that could cover all the mosfets, and put a thermal pad in between heat sink and mosfets.
Then screw the driver and the heatsink to a base.

I mean like this:
heat sink _driver

A heat sink is worthless in a dust and dirt situation.
Paul

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Where did you get that you need a heat sink, the manufacturer forgot about it? If mosfet is completely on or off there is no much heat, the IC controlling mosfets do that job. = beauty of PWM/mosfet.

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Well, the provided link above is an Amazon-link, and the unit is sold without heat sink. Which is a kind of bad because mounting the things is the highest challenge here ...

About thermal pad/paste: I like Capton foils. Low thermal resistance, superior voltage isolation capabilities, clean (fingers after assembly), ... expensive. Here I think any foil is fine, it is not about a class A amplifier ...

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Not fully understood, but if you like to build a sandwich consisting of (big heatsink) - (small mounting plate) - (PCB with MOSFETs) you can do so. Contact area between mounting plate and big heat sink will provide good thermal conductivity ... hm, with paste, ... even though I just wrote something different, but for larger surfaces paste is better choice.

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The purpose of the paste is fill in the micro voids in both pieces of metal so heat conductivity is improved. All other parts of the metal surfaces rely on direct metal-metal contact.
Paul

I will try without heatsinks , if mosfet get hot (not warm ) then consider heatsinks, I will go with drawing post #6,

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Late to the party but, if there's clearance between the device metal tab and the PCB you might could use push rivets (McMaster-Carr) to fasten the heat sink.

image

YMMV

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Completely untrue, heatsinks work even if they are dirty - perhaps not so well, but way better than not having a heatsink.

Thermal pads should have a thermal resistance rating in degrees-per-watt, and heatsinks will have one too, so its possible to calculate heat-rise for particular devices.

Active air circulation will improve performance of heatsinks a lot (but not such a good idea with lots of dust as it can simply build up more dust). In a dusty environment best to put things in a box (larger boxes will cool better than small).

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Maatthew,

You will inevitably have to put some screws through your TO-220. I would opt for two heatsinks one for each row. Reason it might be more difficult to get the to-220's flat to the heatsink.

If you don't expect them to get too hot you can use nylon screws, else you will need metal with something so the screws don't touch the tabs. For hobby I use a couple layers of heatsink on the screw.

I have some double sided thermal tape 3/4" wide that was used in an automotive application. If you PM me I will send you some.

John

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Thermal kits should include the isolating plastic top-hat washers for insulating the transistor tab from the screw. Don't use nylon screws for heatsinks they get brittle with heat and age and might eventually fail. If you must use plastic screws go for a high-temperature plastic like PTFE or PPS.

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Hi,
I was about to echo @MarkT comment about insulating washers.
If you want to use ONE large heatsink you will possibly have to insulate EACH MOSFET as the tabs are also, unless a special type of case, connected to the center lead of the MOSFET.
download (2)

Tom... :grinning: :+1: :coffee: :australia:

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Put board on heat sink and use 4x M3 screw


plus thermal-pad

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