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Reddit told me to buy this – PTM7950 Thermal Pad

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PTM7950 looks like any other thermal paste that you might find pre-applied to a heatsink or squeeze out of a tube… only it’s not, because once this material gets above 45 degrees, it starts to MELT! But what does that actually mean the components you would use it on?

 

 

Buy Noctua NT-H2 Thermal Compound: https://geni.us/ILGpc
Buy Thermal Grizzly Conductonaut Liquid Metal: https://geni.us/t4QPe0
Buy IC Graphite Thermal Pad: https://geni.us/ofvCl
Buy Honeywell PTM7950 from modDIY: https://lmg.gg/iBCQ1
Purchases made through some store links may provide some compensation to Linus Media Group.

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This is also how the thermostat in your car works to regulate the flow of antifreeze in your engine.

There also use to be applications of this years ago where they would use wax to cool components. It works because melting is extremely endothermic (It absorbs a ton of heat).

 

Unfortunately it has limitations because once melted, the material cannot absorb any more heat, until it solidifies again. This is probably different with the material in this video because it might have a melting/freezing point near the temp of the cpu so that it rapidly transforms back and forth. But overall, the fact that it cannot continuously absorb heat like a fan or heat sink, is a serious bottleneck

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Is it hard to remove once it resolidifies if you turn off your computer for an extended amount of time?

 

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29 minutes ago, Shreyas1 said:

Is it hard to remove once it resolidifies if you turn off your computer for an extended amount of time?

I don't actually know, but I could venture to guess that it would depend on the surface, similar to 3d printing

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In manufacturing I can see some advantage to using a decent pad instead of a paste.

Adding a pad is something that can be done far more consistently in volume production than a paste.

 

However, a lot of paste is deposited with a silk screen process, so consistency is fairly decent already. But paste has a risk of causing a spreading mess over time something a pad wouldn't.

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The testing done in the video was bad and lazy - I would consider the results invalid.

 

1.TIM matters less on direct die cooling (like in a graphics card), especially when the cooler is overkill and the temps are below 75C

 

2.Inconsistent thermal load in the CPU test

As for the CPU, You should have turned off turbo, increase the thermal limit to 95C and overclock it,

Then you will be able to get more consistent clock speeds and thermal load and will be able to see which TIM is better.

Just make sure to not overwhelm the cooling solution - The sweet spot is around 85C

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I wonder if the PTM7950 is toxic after heating or by direct skin contact ?

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3 hours ago, that_dude said:

Isn't this bimetall and in new cars electronics?

 

It does, but the thermostat that I'm talking about would be similar to the one in my '95 Cutlass Ciera which did not use any electronics

 

Here's a source of them using wax in a thermostat https://www.counterman.com/watch-understanding-automotive-thermostats/

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It's kinda hard to attach meaning to your testing when you only include one actual temperature graph, where the largest temperature difference is less than three degrees and thermal paste and liquid metal are shown as identical. You even said yourself that the main benefit was supposedly for laptops, where cooling capacity is extremely limited, yet you're using a D15 which clearly isn't struggling at all.

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Looks like the lttstore ad message at around the 3:03 mark didn’t get its video component added.  So audio/video desync from then on.  Watched the video just now, not sure if it was changed at some point.

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There's a top comment on the YouTube comments that I think bears repeating here (shout out to Tedium for the original comment): if this stuff can only authentically be bought in bulk, you guys at LMG should put in some bulk orders and then resell it on LTTStore. I think a lot of people would snap at the chance to get this stuff from a reputable source if it's at a fair price, rather than either paying out the wazoo on modDIY or taking a gamble on Chinese resellers.

 

A good opportunity to put your money where your mouth is, don't you think?

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27 minutes ago, VinLAURiA said:

There's a top comment on the YouTube comments that I think bears repeating here (shout out to Tedium for the original comment): if this stuff can only authentically be bought in bulk, you guys at LMG should put in some bulk orders and then resell it on LTTStore. I think a lot of people would snap at the chance to get this stuff from a reputable source if it's at a fair price, rather than either paying out the wazoo on modDIY or taking a gamble on Chinese resellers.

 

A good opportunity to put your money where your mouth is, don't you think?

You would have to sign up for licenses and everything to be able to resell them, its more complicated then LTT just buying a bunch then re selling. 

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What a pity that Linus didn't show the results for the "fake" PTM7950 from aliexpress.

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Now I'm curious to see this concept using a steam deck, switch, and maybe a cellphone or network switch. 

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On 11/27/2022 at 10:39 PM, Nystemy said:

In manufacturing I can see some advantage to using a decent pad instead of a paste.

Adding a pad is something that can be done far more consistently in volume production than a paste.

 

However, a lot of paste is deposited with a silk screen process, so consistency is fairly decent already. But paste has a risk of causing a spreading mess over time something a pad wouldn't.

Screen printing these pastes has issues! Either you pre-apply it to the heatsink and then have to handle heatsinks with paste on them, which most assembly houses will hate you for - the ones we dealt with at work much rather applied it manually with a syringe or using an automatic dispenser than deal with pre-coated heatsinks. You already have workers to put on the heatsinks, so having them do one more step is not that much more expensive really.

 

Now if you wish to screen print paste on the PCB, you got another issue: different height levels. This requires pricey electroformed stencils/screens with special squeegees. Which rapidly starts adding up the cost unless if you're planning to manufacture a couple of thousand of these a day. Because all that paste you put on the screen printer usually needs to go on the trash can in the evening because the matrix material tends to evaporate or harden.

 

Basically, pads for the win from a mass manufacturing point of view!

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28 minutes ago, ImorallySourcedElectrons said:

Screen printing these pastes has issues! Either you pre-apply it to the heatsink and then have to handle heatsinks with paste on them, which most assembly houses will hate you for - the ones we dealt with at work much rather applied it manually with a syringe or using an automatic dispenser than deal with pre-coated heatsinks. You already have workers to put on the heatsinks, so having them do one more step is not that much more expensive really.

 

Now if you wish to screen print paste on the PCB, you got another issue: different height levels. This requires pricey electroformed stencils/screens with special squeegees. Which rapidly starts adding up the cost unless if you're planning to manufacture a couple of thousand of these a day. Because all that paste you put on the screen printer usually needs to go on the trash can in the evening because the matrix material tends to evaporate or harden.

 

Basically, pads for the win from a mass manufacturing point of view!

Most places I see the silk screen process in use is just before the heatsink gets attached to the board and mainly for a single package. So handling isn't a major concern unless one pushes that as a criteria as the product owner. (Or has another subcontractor apply the paste elsewhere, and this is usually not ideal.)
 

Pads are indeed a superior solution in manufacturing if one just needs basic heat sinking, and more or less the only reason why thermal pads even exist. But it doesn't change the fact that most thermal pads are inferior in performance to paste. So paste it still used.

 

Back in the "good old days" before thermal pads, then one just used a thicker paste that dried into a somewhat thermally conductive blob. And this product category still exist since it effectively is glue/silicone/adhesive. But it can be a bit of a mess to handle. (Since it will occasionally drip, smear and spread over the workbench and products, unless one has a procedure in place for preventing this mess, not uncommonly a whole bunch of paper towels.)

 

I have yet to see any multi height silk screening process in use myself. (I do work in electronics design and manufacturing, so this is my field.) That sounds oddly inept as a solution in the vast majority of cases. (But engineers likes building things to strict criteria, even if said criteria are inept for the application. Bureaucracy is a time consuming mess in larger companies so changing the criteria isn't always the easiest option. So I wouldn't be surprised if a factory did have a multi height silk screening process for handling ancillary components around a processor. Sometimes it might be the only reasonable solution, but likely not that often. I have seen plenty of other far more actually stupid solutions set forth by inept criteria.)

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14 minutes ago, Nystemy said:

Most places I see the silk screen process in use is just before the heatsink gets attached to the board and mainly for a single package. So handling isn't a major concern unless one pushes that as a criteria as the product owner. (Or has another subcontractor apply the paste elsewhere, and this is usually not ideal.)

It depends a bit on what the assembly house is familiar with I suspect. We also had to deal with criteria for military assemblies, so that kind of introduces extra strictness on things logging lot numbers, pot life, etc. But I vividly recall the owner of the assembly house stating that he'd still prefer having his staff apply it manually, because it was cheaper and easier for him to have workers sit there with syringes than to give each of them a small printing station.

 

16 minutes ago, Nystemy said:

Back in the "good old days" before thermal pads, then one just used a thicker paste that dried into a somewhat thermally conductive blob. And this product category still exist since it effectively is glue/silicone/adhesive. But it can be a bit of a mess to handle. (Since it will occasionally drip, smear and spread over the workbench and products, unless one has a procedure in place for preventing this mess, not uncommonly a whole bunch of paper towels.)

We had this concern at one point for something, we asked the board house to leave the peelable soldermask they used during a plating step on to protect the pads where the pogo pins went. Was a pretty cheap and easy solution that most PCB designers don't seem to realise exists.

 

17 minutes ago, Nystemy said:

I have yet to see any multi height silk screening process in use myself. (I do work in electronics design and manufacturing, so this is my field.) That sounds oddly inept as a solution in the vast majority of cases. (But engineers likes building things to strict criteria, even if said criteria are inept for the application. Bureaucracy is a time consuming mess in larger companies so changing the criteria isn't always the easiest option. So I wouldn't be surprised if a factory did have a multi height silk screening process for handling ancillary components around a processor. Sometimes it might be the only reasonable solution, but likely not that often. I have seen plenty of other far more actually stupid solutions set forth by inept criteria.)

The usual scumbags supply these sort of things, like Dek comes to mind: https://psp.smt.asmpt.com/en/asm-stencils/stencil-technologies/dek-electroform-3d-stencils/  Though we generally used a German manufacturer who's name I can never remember. But it's actually quite a nice solution, you can get some clearance from the PCB except in the spots where you're printing. We've used it to assemble things like book-binded flex-rigids where you'd normally be in some trouble if you used a regular stencil or emulsion screen, and it also allows you to put down carbon pads for certain types of membrane switches without having to worry about the maximum soldering temperatures, etc. These sort of screens also allow you to vary the printed thickness in various locations if the apertures on the stencil are designed correctly, so you can assemble those big fat power FETs together with 0201 SMD resistors in one pass without having to resort to vapour phase soldering.

 

But where I really run into it very often is my current job, I switched to the dark side - microfabrication/packaging R&D - at one point in my career. In terms of IC packaging and chip fanout technologies it's becoming very popular very quickly. It's a nice clean solution that doesn't require trickery or being "creative" with process step orders. Otherwise you're always sitting there thinking about "how will I get material X there without using this really expensive and ultra slow dispenser". Now you can just slap a screen printer in the production line and shove a wafer through it every couple of seconds. Screen printing is nice because it's quick, repeatable, and above all it's so dirty cheap. That fancy dispensing system needs maintenance frequently and an AOI because it's quite unreliable, so the cost of ownership is quite high.

 

Meanwhile, a high quality second hand screen printer with optical alignment will set you back less than a reliable table top dispenser with manual loading. And screen printers are extremely reliable. Heck, we recently fired one up that had been sitting in storage for over a decade with zero maintenance, we dragged it back into the cleanroom, removed the plastic wrapping, oiled the necessary bits, installed a new squeegee, and it printed a couple of hundred sheets on the first go with zero hick-ups. So it's not based on strict criteria, it's just a very economical solution to a common manufacturing problem using an extremely reliable piece of equipment.

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  • 4 weeks later...

I am a bit confused by the testing in the video.

 

Is PTM7950 supposed to perform better or worse than a Carbonaut graphene pad?

 

Carbonaut is supposed to be slightly worse by 1-3C than traditional thermal paste.

And the PTM7950 is supposed to rival high end TIM so the answer is yes?

 

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Is there an american seller for this product anywhere? I don't want to spend a ton on shipping

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