Thermal paste replacement interval

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antiscab
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Thermal paste replacement interval

Post by antiscab »

for those who regularly deal with thermal paste and heat sinks, do you have a change out interval that you use, due to the paste drying out?

apparently this is common in the computer industry, where the heatsinks are connected to heat loads (CPUs, GPUs and now RAM) that run at around 60-70 deg C continuously

I have always treated heat sink compound as basically lasting forever, as long as it isn't disturbed.
I've never changed the heat sink compound in a computer, and not on a motor controller

Just about every Vectrix motor controller that I have removed has had dried out heatsink compound
I generally only remove a motor controller if it has died
I now wonder, if the reason the IGBT's in Vectrix motor controllers wear out, is because they overheat due to dried out heat sink compound not conducting the heat to the heat sink as effectively as it should leading to hotspots (It's only been 10 years, but maybe I'm slow on the uptake here)

do VFD manufacturers expect the IGBT modules to be periodically removed and heatsink compound replaced as preventative maintenance?
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4Springs
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Re: Thermal paste replacement interval

Post by 4Springs »

Interesting.
I can tell you that the heatsink paste I put under my Kelly controller was still pasty after about 5 years. Still liquid enough to drip out over everything. This is a much larger surface area than your average computer GPU, so I guess it is further from the air which might dry it out.
antiscab
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Re: Thermal paste replacement interval

Post by antiscab »

4Springs wrote: Tue, 15 Jun 2021, 19:17 I can tell you that the heatsink paste I put under my Kelly controller was still pasty after about 5 years. Still liquid enough to drip out over everything. This is a much larger surface area than your average computer GPU, so I guess it is further from the air which might dry it out.
That was my thinking - the vectrix IGBT module measures 135mm x 110mm
I wouldn't have expected it to dry out either

what heat sink compound do you use?
Matt
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T1 Terry
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Re: Thermal paste replacement interval

Post by T1 Terry »

It was a common fault back when the electronic ignition module was on/in the distributor. The module would fail and it was always heat related due to the compound drying out.
It was a bit like Honda's claim that the power steering fluid was designed to last for life, when the steering components failed the end of life was determined ...... Everything in the steering system that the oil flowed through was deemed to be at "end of life" A sure thing service and sales intuitive and Honda owners swore by it, the book says the oil never needs changing ......

A guess a method of measuring the component and heat sink temp would indicate when the heat transfer paste required replacement because it is purely a heat related problem. We use the Jaycar white stuff on the solid state relay to heatsink contact, lots so it covers the whole face with a thick coating and squeezes out when screwed down, the only time we see a drying out problem is when the SSR is pushed close to its maximum rating or the fan fails.

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4Springs
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Re: Thermal paste replacement interval

Post by 4Springs »

antiscab wrote: Wed, 16 Jun 2021, 08:14 what heat sink compound do you use?
PXL_20210619_014757981.jpg
PXL_20210619_014757981.jpg (10.86 KiB) Viewed 1987 times
Not sure where I got it, possibly Jaycar.
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Re: Thermal paste replacement interval

Post by jonescg »

Unicked it.


@antday would be proud.
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Re: Thermal paste replacement interval

Post by antday »

@jonescg Groan...
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Re: Thermal paste replacement interval

Post by Paul9 »

In case it is of interest I use double sided thermal transfer paper.

It is not sufficiently "sticky" to bear much weight but works fine in a non loading bearing situation.

I have heat sinks stuck on with it for over five years now without problems.

Cheers
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Re: Thermal paste replacement interval

Post by 4Springs »

Paul9 wrote: Sun, 20 Jun 2021, 11:07 In case it is of interest I use double sided thermal transfer paper.
I've seen that in very tiny sheets, but I couldn't find it in sheets large enough for my applications. How big is what you use?
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Re: Thermal paste replacement interval

Post by T1 Terry »

Is there a double sided sticky heat transfer material or heat paste the ISN'T electrically conductive? I have a heap of the cell top resistance type balance boards that I'd like to mount to a heat sink tunnel with thermostats on each face to turn on a fan if the heat sink reaches 50*C to see if that will stop the cell top boards failing when I do the house battery memory charge clearing.

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Re: Thermal paste replacement interval

Post by smithy2167 »

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Re: Thermal paste replacement interval

Post by brendon_m »

I clicked that jaycar link and it loaded the page and showed me the bottom of the page first.
This is what I saw.
Screenshot_20210620-165722.png
Screenshot_20210620-165722.png (217.95 KiB) Viewed 1951 times
It wasn't until I scrolled back to the top of that page that I realised you weren't pulling the piss
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smithy2167
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Re: Thermal paste replacement interval

Post by smithy2167 »

Sorry 'bout that. Here's what I was referring to:

Thermal Tape.jpg
Thermal Tape.jpg (86.64 KiB) Viewed 1944 times
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Re: Thermal paste replacement interval

Post by Paul9 »

Yep the NM2790 from Jaycar is the stuff I use
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Re: Thermal paste replacement interval

Post by T1 Terry »

Thank you all, that was exactly what I was looking for, the painful part is, I asked at the local Jay Car last visit if they knew of any such product and I just got the wide eyed look like I'd asked for unobtainium or similar ...... Now, armed with the part number I'll have another crack at it and see if I get the same wide eyed look :lol:

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Re: Thermal paste replacement interval

Post by mjcrow »

I use Kryonaut https://www.thermal-grizzly.com/en/prod ... ryonaut-en on all my cpu and gpu applications, if you maintain the temp under 80°C it won't dry out. It is expensive but you don't use much. The company that makes it also make thermal pads in both electrically conductive and non-conductive forms https://www.thermal-grizzly.com/en/products.
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Re: Thermal paste replacement interval

Post by rhills »

Hi Terry,
T1 Terry wrote: Tue, 22 Jun 2021, 11:10 Thank you all, that was exactly what I was looking for, the painful part is, I asked at the local Jay Car last visit if they knew of any such product and I just got the wide eyed look like I'd asked for unobtainium or similar ...... Now, armed with the part number I'll have another crack at it and see if I get the same wide eyed look :lol:
If you want to save a potentially fruitless trip to Jaycar, I suggest going buying the product online and specifying pickup at your local Jaycar. Either they'll have it in stock and keep it for you, or they'll get it in and let you know when it's available for collection.

https://www.jaycar.com.au/click-and-collect

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Re: Thermal paste replacement interval

Post by evcruiser »

The Unick was from WES / Wagner Components NSW
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