Smartphone SoC cooling (ASUS ZenFone 2 - ZE551ML)

[itsakjt]

So I recently took apart my ASUS ZenFone 2 (4 GB RAM, 16 GB ROM, 1.8 GHz Intel Atom Z3560) to take a look inside. The internal build quality is very good. But the cooling system is like: There is copper tape covering a thin aluminum plate which is placed on top of the SoC area for shielding. The copper tape has direct contact with the RAM with adhesive (the CPU is underneath it - POP). That same copper tape continues to the mid-frame (metal) and is fixed there with adhesive also.
I don't think this is a very efficient way of cooling the device. I am thinking about exposing the RAM by cutting part of the copper tape where it is kept in contact with adhesive with a thermal pad or a kinda "hard" thermal compound.
What do you guys suggest?

 

[Recon-UK]

I suggest putting it back together and returning the phone for a better one, you will most likely end up breaking something.

 

[Palutena]

Just return the phone for a new one, You might break something in it

 

[itsakjt]

I suggest putting it back together and returning the phone for a better one, you will most likely end up breaking something.

I won't do that I am confident enough. I have put back the phone like it was and it is working perfectly fine just like it did. The call clarity has improved slightly since I removed all the dust from the earpiece.
I am thinking of modding the cooling since the phone has a tendency to heat during video recording and it is a known issue with this particular model.

 

[itsakjt]

Just return the phone for a new one, You might break something in it

Nothing is wrong with the phone. The phone functions perfectly and nothing is wrong with it. I just want to improve the cooling system.
I have seen teardown of quite a few phones and many of them have thermal pad over the SOC which is kept in contact with the mid-frame metal. So just want to have some opinion before doing it.

 

[Palutena]

Yeah mod it with a better cooling system and you should be good

 

[Ferrum Master]

Don't fix what ain't broken.

You will introduce pressure, bending to other parts of the construction... so it may pop out - for example the glued in screen from the front cover chassis.

Don't touch it. You may replace some copper sheet with same thickness graphite sheet. Yes that may work... but no funny ideas like that. Thermal pads are not that good btw.

 

[Bill_Bright]

Are you a thermal engineer who specializes in the cooling of electronics? If not, don't try to fix something not broke.

Adhesive TIM (thermal interface materials) are commonly used in compact electronics. They are very effective (when properly applied). And of course, copper is the best metal conductor of heat (besides more expensive silver). By removing the copper tape, you ruin its effectiveness because you can never properly re-apply it.

Sadly, you have clearly voided the warranty now just by opening the case. So if you return it without being forthcoming about you taking it apart and attempt to get a free replacement or credit towards a new phone, that is felony fraud!

 

[itsakjt]

Don't fix what ain't broken.

You will introduce, pressure, bending to other parts of the construction... so it may pop out - for example the glued in screen from the front cover chassis.

Don't touch it. You may replace some copper sheet with same thickness graphite sheet. Yes that may work... but no funny ideas like that. Thermal pads are not that good btw.

Got it. And what about thermal compound? Will that do a good job? Suppose I put in some thermal compound between the SoC and the mid-frame which is aluminum?

 

[itsakjt]

Are you a thermal engineer who specializes in the cooling of electronics? If not, don't try to fix something not broke.

Adhesive TIM (thermal interface materials) are commonly used in compact electronics. They are very effective (when properly applied). And of course, copper is the best metal conductor of heat (besides more expensive silver). By removing the copper tape, you ruin its effectiveness because you can never properly re-apply it.

Sadly, you have clearly voided the warranty now just by opening the case. So if you return it without being forthcoming about you taking it apart and attempt to get a free replacement or credit towards a new phone, that is felony fraud!

I have no plans for returning the phone. I know that it is not possible to re apply the copper tape in the way it was before and I have done everything after knowing it. But all I know is with a bit of thinking, I can try experimenting with thermal compound or other stuff. If it does not work, I can always buy some copper tapes and make it good as new as it was before I took it apart. There's nothing much to be damaged here and I am confident that I won't ruin anything apart from the copper tapes and replacement shield tapes (consumables) which are also easy to get.

Ps. I always thought this forum is about DIY. And that is exactly what I am thinking of. Many of us have come across products which we have made better by modding them in an effective way.

Also, my phone has the famous ghost touch disease happening for a month or so. I have talked with the service center and they have said they will replace the touch panel assembly since it is under warranty. I asked them if I can take a look inside and think of improving the cooling without voiding the warranty and I got their permission. The only condition I have is not to mod part of the mid-frame since it will be replaced.

 

[silentbogo]

So I recently took apart my ASUS ZenFone 2 (4 GB RAM, 16 GB ROM, 1.8 GHz Intel Atom Z3560) to take a look inside. The internal build quality is very good. But the cooling system is like: There is copper tape covering a thin aluminum plate which is placed on top of the SoC area for shielding. The copper tape has direct contact with the RAM with adhesive (the CPU is underneath it - POP). That same copper tape continues to the mid-frame (metal) and is fixed there with adhesive also.
I don't think this is a very efficient way of cooling the device. I am thinking about exposing the RAM by cutting part of the copper tape where it is kept in contact with adhesive with a thermal pad or a kinda "hard" thermal compound.
What do you guys suggest?

It's a sub-2W CPU, which does not need a lot of cooling.
The same cooling setup is used in lots of devices, including an infamous Nexus 7. Even a >3.5W Snapdragon 820 uses shield as a heatspreader in almost all devices.

Just leave it alone, or if you experience overheating - RMA it.
You won't be able to connect RF shield with metal backplate, because there is a plastic mid-plate that goes over it. You can cut a hole and stick a thick copper foil between the shield and the backplate (commonly applied hack for hot chinese tablets), but that's simply a waste of good phone.

 

[itsakjt]

Thanks a lot. Actually, the CPU heats up a lot while video recording. Yesterday, I was in an air conditioned room at 24 degree C, recording a video and the temperatures went as high as 70 degree C +.

Seeing this in a smartphone, I was concerned and that was why I took it apart to check if anything can be done.

 

[Caring1]

I'm interested how this turns out, I know it can be done as I have heard of it before.
My smartphone, also gets quite hot in the CPU region and I was thinking of somehow making the cooling better.
When I open the back up it appears to have no heat spreaders or other means of cooling that I can see, only a plastic housing over the SoC.

 

[itsakjt]

Little update here: So I checked the heat spreader thoroughly and the copper tape was not in contact with the SoC (RAM over CPU as POP architecture) completely. Only the center was kept in contact. I took out the shield and heated the base of the copper tape where the adhesive was there and supposed to be in contact with the SoC.
Please note that there was clear indication that the adhesive was in contact with the SoC only at the center and not throughout the entire area because part of the adhesive was literally "like new" near the sides. After heating it up, I put the shield over the board again and applied some pressure where the copper was intended to be in contact with the CPU thus ensuring contact throughout the entire area. Put back everything together. Today, simulated the exact same scenario - Air conditioned room at 24 degree C and phone recording video @1080p, 30 FPS. Recorded the video for 24 mins (twice of what I did prior to the operation) and the maximum temperature reached 69 degree C (6 degrees less than before).
I am sure using a very thin thermal pad between the copper tape area of contact with the SOC and the metal mid frame which is just at the sweet spot for keeping the contact without deforming anything will yield even better results. Or even thermal compound will do a good job.

Performance enhancements:
1. To my surprise, the phone now boots up a lot faster than it used to do before. The loading icon rotated 31-34 times while booting prior to the operation. Now it is 20-22 times. Not sure for what it is because during the process, I cleaned the motherboard with IPA as well.

2. The GPU clock is now being shown as 533 MHz in CPU-Z which is the burst frequency for the Intel Atom Z3560, something I never saw before throughout the entire lifetime of the phone. It was always 457 MHz before.

 

[itsakjt]

Some photos:

The last photo shows the mod. Note the square block on the SoC area in the copper tape. That part is meant to be in contact with the SoC but it was not assembled that way from the factory.

 

[jboydgolfer]

Nice work