Thermal pad how large piece to cut ?

[user33331]

Hello ( Laptop's Intel MCH=memory controller hub )
ARCTIC thermal pad sheet: ( Replacing a worn out pad on laptop )
Do I cut the pad so that it covers the whole chip ? ( the green part with tiny SMDs also ? ) This would make it about "50x50mm".
Or
Can I cut it smaller so that it covers just the metallic mirror piece in the center ? This would make it about "30x20mm".

The original one placed in China is larger 50x50mm but is it necessary ? These 1mm thick sheets cost a lot. 16usd$=145x145x1.0mm.

 

[flmatter]

I would match the one that came off the original, just to be safe.

 

[user33331]

How about CPU and GPU chips ?:
Should I use thermal pad (50x50) which has the center(30x20) cut off and replaced with paste ? Or just plain paste on center without thermal pad linings ?

 

[Totally]

If the chip you are drawing is is a gpu/cpu. You are doing it wrong, very wrong. Just use paste if that was what was there before, but if there pad before hand make sure you've got the correct thickness, using a pad or pad + paste will most likely result in high temps or worse. The 'metallic mirror piece in the center' is the die and the component that is actually generating heat the rest of the chip is just traces and other minor components that don't really need to be cooled. Anyway to answer your question cut the pad so it fully covers the die, (mirror piece).

 

[user33331]

Original chip is Lenovo laptop's Intel MCH=memory controller hub chip.="Northbridge".
- So I can use just a small pad that covers the center die ?

 

[Totally]

Yes

 

[user33331]

Why "PCI to AGP bridge" has a cut-off center in thermal pad ? What is the science behind to cut or not to cut ?

 

[eidairaman1]

Why "PCI to AGP bridge" has a cut-off center in thermal pad ? What is the science behind to cut or not to cut ?
View attachment 100136

Ask the engineers.

Match the pad that came off.

 

[Jetster]

Why "PCI to AGP bridge" has a cut-off center in thermal pad ? What is the science behind to cut or not to cut ?
View attachment 100136

the larger piece is there to protect the components around the chip. Just make it the same size as the original

 

[user33331]

Should I also protect the CPU and GPU chips' tiny SMD-components by placing a pad+paste on them ? Why only paste mentioned in guides ?

 

[Jetster]

Should I also protect the CPU and GPU chips' tiny SMD-components by placing a pad+paste on them ? Why only paste mentioned in guides ?

View attachment 100137

No, paste only goes on the die, and don't over do it

 

[MrGenius]

Just put it back together how it was to begin with. Using paste in an application that wasn't designed for it is not always a good idea.

The reason that pad on the bridge chip doesn't cover the die is because it's not being used as a thermal interface. That die is not heatsinked. If the pad covered it, it would act as insulation. Causing it to run hotter.

 

[John Naylor]

You can find some nice pad installation instructions by reviewing EK GPU Block and backplate instructions.

https://www.ekwb.com/shop/EK-IM/EK-IM-3831109868430.pdf
https://www.ekwb.com/shop/EK-IM/EK-IM-3831109869260.pdf
https://www.ekwb.com/shop/EK-IM/EK-IM-3831109868348.pdf

Note the recommendation with regard to using TIM on the pads. Not also how one pad is used to span over as many as 8 surfaces.

 

[jsfitz54]

The paste will degrade the thermal pad.
Do not mix.

 

[eidairaman1]

The reason makers have oversized pads is because it is easier to handle, not much worry of getting the pad on the die correctly either so just cut it to same size or cut it a little bigger than the die itself, attach it and be done with it.

 

[peche]

Ask the engineers.

Match the pad that came off.

+1, match the ones that came with the laptop, try to clone them with the new thermal pad you just got,

The reason that pad on the bridge chip doesn't cover the die is because it's not being used as a thermal interface. That die is not heatsinked. If the pad covered it, it would act as insulation. Causing it to run hotter.

+1

 

[John Naylor]

The paste will degrade the thermal pad.
Do not mix.

Reference please... since that directly contradicts manufacturer's installation instructions, I'm anxious to see who's contradicting the world's prominent block manufacturer.

 

[sneekypeet]

Reference please... since that directly contradicts manufacturer's installation instructions, I'm anxious to see who's contradicting the world's prominent block manufacturer.

Newer instructions do not make such a comment.... Found from the 1080 block install literature. Not saying either is more right, but maybe they had reason to eliminate the use of TIM in the instructions? I need to look around and see if I have any EK pads lying around and put a bunch of TIMS on it!

 

[John Naylor]

The 980 ... says same thing... The 10xx series has a change and I'm not sure why as I haven't seen one to be able to see if they are different in any way. At first thought, I was thinking that perhaps they were using a new thermal pad that has some surface coating that makes it unnecessary. Thinking further ... if we look at what vendors have done efficiency wise of late, that may be the key. If ya remember, back in the 7xx and to a lesser extent the 9xx series, VRMs and memory were hitting some pretty high temps. Now thermal imaging shows that temps at most points are significantly lower on current cards. Some vendors, notably EVGA opted to even leave out thermal pads in the 10xx series .... and then had to do a recall because w/o pads they were frying. My assumption is that the decision was, with the more efficient card designs, that the pads were deemed sufficient for the current generation cards and not worth the hassle of applying paste to over a dozen contact points.

But while the "need" or relative benefit of doing so may be subject to discussion, there is no evidence that applying TIM to a pad degrades it in any way.

 

[jsfitz54]

But while the "need" or relative benefit of doing so may be subject to discussion, there is no evidence that applying TIM to a pad degrades it in any way.

The TIM melts (or eats into) the silicone pad. This is my personal experience. I did not take pictures of the FUBAR'ed pad from one of my laptops.
The pad was pink in color if that helps.

 

[R0H1T]

The TIM melts (or eats into) the silicone pad. This is my personal experience. I did not take pictures of the FUBAR'ed pad from one of my laptops.
The pad was pink in color if that helps.

That depends on the paste's chemical composition, not all TIM will degrade a thermal pad.

 

[jsfitz54]

That depends on the paste's chemical composition, not all TIM will degrade a thermal pad.

Please post a list of what pads work with what pastes. Please be brand specific, so we know what compositions work together.

 

[eidairaman1]

Newer instructions do not make such a comment.... Found from the 1080 block install literature. Not saying either is more right, but maybe they had reason to eliminate the use of TIM in the instructions? I need to look around and see if I have any EK pads lying around and put a bunch of TIMS on it!
View attachment 100235

Aren't they called Thermalpads for a reason?

 

[sneekypeet]

Aren't they called Thermalpads for a reason?

Why are you asking me this? I know what they are. I was replying to John to show the difference in instructions.

 

[eidairaman1]

Why are you asking me this? I know what they are. I was replying to John to show the difference in instructions.

I was thinking thermal interface material-thermalcompound wasn't necessary if thermal pads were being used, excluding die of course.