PCB cooling, how do you do it?

[Noci]

It's not about cooling the PCB for it's own sake, but that the PCB can influence temperatures of RAM, chipset, socket etc. There's reasons people put thermal pads on the backside of mobos, or have direct airflow etc.

I support this, as that what it says in that study also, but it's not the whole story.

After reading some more I saw that heat dissipiating techniques is already a thing in PCB design also, no doubth all the PCB manufacterers will use every trick in the book so we don't have to worrie too much.
But my gut feeling about cooling with air is not so crazy after all when I read the article in the link below:

https://www.mclpcb.com/blog/heat-dissipation-techniques/

Guess you're never too old to learn

 

[A Computer Guy]

They can take a lot of heat. If you get to this point then you know something went very very wrong.

 

[Noci]

@ A Computer Guy,

Too many amps through the PCB?
Looks like PC horror and I guess it was running a little bit above specs

 

[A Computer Guy]

@ A Computer Guy,

Too many amps through the PCB?
Looks like PC horror and I guess it was running a little bit above specs

Here is a link to a subpost with indexed links to the story. Just go to page 1 to start from the beginning. Enjoy.

5950x and PBO overheated something or busted custom loop?

Anyone have any recommendations on the right equipment/parts to use for temperature monitoring that can be picked up by HWiNFO64? I want to attach multiple thermal sensors to a used Master SLI/ac (the motherboard that started this thread) that I was able to pick up dirt cheap. Various...

www.techpowerup.com

 

[Chrispy_]

Good thing I can still amuse somebody with a techincal question. But where in this thread did you get the idea of somebody being afraid of the PCB catching fire ?

I personally find it amusing how quick a discussion can deviate from its intended purpose without reason.

The original question was to share knowledge/idea's of the fact that the traces on the PCB to the main users show a higher temp than the adjecent parts and if this is or will be noticeable at a certain point in the form of performance loss.
The fact that my gut feeling is that at least I cool a little with just providing a airflow on both sides of the PCB could be wasted energy, but why not it doesn't harm also. I cannot substatiate this by facts (measurements), but prove me wrong

That the question of cooling PCB's is not completely out of the blue is proven by the fact that already two decades ago there was scientific research on cooling PCB's, see the publication in the link below for example:

https://www.researchgate.net/profil...s-Fabricated-With-the-Direct-Write-Method.pdf

My knowledge of printed circuits and electronics is very limited, just the fact that: from Ohm's law, we know that resistance is inversely proportional to current. That is, the lower the resistance, the higher the current and vice versa. Current is also proportional to power according to P = VI. Thus, resistance also becomes a factor when calculating power consumption. It is important to determine the resistance of the trace of a microstrip so that the power dissipated by it can be determined (this text I took from a Trace Resistance Calculator website ).
So with the ever increasing power demand of our hardware this got me wondering how far can we stretch it with the current PCB technology.

So some food for thoughts for the skeptical ones amongst us .

The copper traces in the PCB conduct heat from the components, so they act as a kind of shitty, inefficient heatsink. If you cool the PCB, you are simply taking heat out of the system at a different point. It's not bad to cool the PCB, but it's also not efficient to cool the PCB since dedicated heatsinks with fans more efficiently transfer heat to the air for any given amount of airflow, since there's no insulating fibreglass in the way and you end up with more heat removed per fan speed/power/noise.

No uncooled components on the PCB care about the temperate they run at (within normal PC operating temperature ranges) and the "catching fire" part was more hyperbole to say that by the time the PCB temperatures are an issue, the other components would already be on fire and all the solder would have melted, rendering the idea of PCB temperature concerns irrelevant

They can take a lot of heat. If you get to this point then you know something went very very wrong.

View attachment 329861

OOF. Too many Amps for sure Those copper traces likely reached red-hot at around 1000C (1800F) hence the PCB damage.
No amount of air cooling could have solved that!

 

[Shrek]

The copper traces in the PCB conduct heat from the components, so they act as a kind of shitty, inefficient heatsink.

If you ever tried to remove the capacitors from a motherboard, it does not seem so inefficient.

 

[Chrispy_]

If you ever tried to remove the capacitors from a motherboard, it does not seem so inefficient.

You're implying they're good conductors?
That's not the same thing as being good heatsinks.

 

[Shrek]

I meant desoldering capacitors with the heat of a soldering iron.

 

[LabRat 891]

This topic is of special interest to me.

Next chassis swap,
I'll be taking a 1U LGA2011 full-copper heatsink, and drilling it out to match AM4's mount.
Basically, it'll be a heat-dissipating 'backplate' (Thermal Putty TIM) for my CPU socket and surrounding traces+components.

 

[Shrek]

Seems to me there are 3 factors

* ability to conduct hear (thermal conductivity)
* ability to absorb heat (specific heat)
* ability to dissipate heat, which is a surface thing

if this is drifting off topic, I can stop.

 

[Chrispy_]

Seems to me there are 3 factors

* ability to conduct hear (thermal conductivity)
* ability to absorb heat (specific heat)
* ability to dissipate heat, which is a surface thing

if this is drifting off topic, I can stop.

Off topic? This whole thread started off-topic from the first post

Yes. Thermal conductivity is important in a heatsink, but the hot surface has to be in contact with a fluid (air or liquid) to transfer that heat, and fibreglass PCB is a near-perfect polymer-ceramic insulator, the exact opposite of what you want and one of the single worst choices of material you could possibly imagine for a heatsink. When you desolder capacitors, the heat is mostly travelling down traces, not through the PCB itself.

From a heat perspective, motherboard traces are like copper water pipes and the PCB is like that foam lagging that keeps the heat in them.

 

[Noci]

The copper traces in the PCB conduct heat from the components, so they act as a kind of shitty, inefficient heatsink. If you cool the PCB, you are simply taking heat out of the system at a different point. It's not bad to cool the PCB, but it's also not efficient to cool the PCB since dedicated heatsinks with fans more efficiently transfer heat to the air for any given amount of airflow, since there's no insulating fibreglass in the way and you end up with more heat removed per fan speed/power/noise.

No uncooled components on the PCB care about the temperate they run at (within normal PC operating temperature ranges) and the "catching fire" part was more hyperbole to say that by the time the PCB temperatures are an issue, the other components would already be on fire and all the solder would have melted, rendering the idea of PCB temperature concerns irrelevant


OOF. Too many Amps for sure Those copper traces likely reached red-hot at around 1000C (1800F) hence the PCB damage.
No amount of air cooling could have solved that!

Well 'A Computer Guy' clearly exceeded the capabillites of the copper traces in that PCB but after reading most of the related thread I'm still in doubt.

Everybody there is only blaming the VRM's, but looking at his pictures I only see deformed traces/PCB, a partially molten socket and some collateral damage. No doubt the louzy VRM's had the leading roll in it, but it's the heat in the traces/PCB from the VRM's to the socket that resulted in the damage (the way I interpret the visual damage).

Luckily we have a wide choice of motherboards now where there are proper components used and with the PCB design all rules of thermal management techniques are applied. It is mainly a matter of informing yourself with the aid of technical reviews. The biggest problem however, is to seperated the BS from valuable info if like me, you have limited electro technical knowledge.

But the more I'm browsing on scientific papers/researches regarding this subject, I wouldn't be suprised if in the (possible near) future we'll see PCB's with an intergrated cooling system within the PCB layers (additional to the cooling techniques we use alredy now). There's also some research on improving in the heatpipe technology with using nano-technology, imagine how that would make air coolers even better.

Fior example here a quite recent subject:
Yu, Huaiqiang & Gui, Jinle & Yi, Lijun & Liu, Yulong & Deng, Like & Jiang, Chuangxin. (2020). Multilayer PCBs Embedded with Cooling Microchannels for High Power Electronic Devices in Wireless Systems. 10.1109/IWS49314.2020.9360067. This paper presents an integrated microfluidic cooling
scheme on the multilayer FR4 printed circuit board (PCB)
for high power electronic devices. The fabrication process is
completely based on the standard multilayer PCB technology. A
four-layer FR4 PCB embedded with a cooling microchannel has
been design, fabricated and tested. The fabricated PCB is 2 mm
thick, while the microchannel has a height of 444.6 μm, which is
related to the thickness of internal laminates. Thermal experiment
of the PCB has been performed by using a plastic radio
frequency (RF) power amplifier (PA) device with heat flux of
12.9 W/cm2, whose steady-state case temperature is decreased to
46 °C with a flow rate of 30 mL/min.

Hope these researches will develope soon and hit the consumer pc market, would be awsome.

@ Shrek, right to the point of this thread , but the main question how to get rid of the heat quickly

 

[freeagent]

Needz moar fanz!!!11

Good case flow..

 

[thesmokingman]

Must be really boring out there today...

 

[Shrek]

@ Shrek, right to the point of this thread , but the main question how to get rid of the heat quickly

I'm more concerned about liquid cooling that benefits the CPU/GPU, but denies the board air cooling it might otherwise have got.

 

[BigManLi]

The PCB can soak up a serious amount of heat. This is why higher end motherboards are advertised with thicker ground planes than cheaper ones. It does work as a heatsink as well.

Honestly, you are looking for a nonexisting problem. 37C, if I read your IR image correctly, is well within normal operating temperature. When the PCB is hot enough to increase the heat of other components, then you should start considering your cooling solution.

You would also probably be breaking the laws of physics, since those components are what is generating the heat in the first place.

But that's why there would be utility in cooling the pcb. It's tough and it's absorbing a lot of heat from the other components, so by cooling the pcb it could soak up even more heat from said components. Maybe not a lot, but a few degrees could be the difference between RAM timings being stable or not. It's a lot easier to point a fan at a flat surface than to futz around with specialized ram or vrm cooling.