Hacker News Reader

Comment by userbinator | Hacker News Reader

I see Apple hasn't changed at all --- these memorable pages from the official service manual of many years ago shows what they considered the "correct" amount of paste:

http://attach.mobile01.com/attach/200605/mobile01-514da8fc7f...

http://attach.mobile01.com/attach/200605/mobile01-e89d3804df...

https://www.techpowerup.com/img/06-05-01/lol1qe.jpg

View on HN

Is this a joke? those photos are insane.

I wish. I used to work at an Apple repair shop years ago.

We never could figure out why they had so much in their manuals.

Are you sure those are Apple circuit boards? When and what boards used blue solder mask?

You can see it says "MacBook" in the background. Google white plastic MacBook teardown and you get https://www.ifixit.com/Guide/MacBook+Core+Duo+Logic+Board+Re... which shows blue solder mask

I have some circa 2007-2008 MBP boards lying around that are blue. Based on a quick check of iFixit repair guides, it looks like they stopped using blue when they adopted the unibody chassis.

The last picture comes from the MacBook Pro 2006 service manual.

I believe the first two come from the MacBook (not pro) early 2006 service manual, since the colour of the paste is white instead of the grey of later manuals which show (only slightly) smaller amounts.

I should have looked more closely at the pictures, thanks for the comments.

Seems like way too much for such a small surface area.

Yes, it's definitely excessive. There should be just enough to form a thin film after installation.

Here's a picture from Intel's site showing the correct amount:

https://www.intel.com/content/dam/support/us/en/images/proce...

That's for a processor with a large heatspreader on top, so a small bare-die one like those in a laptop should have proportionally less.

This is mostly urban legend. You have to really get ridiculous to apply too much thermal paste but you can use too little, so no reason to err in that direction in mass manufacturing. https://www.youtube.com/watch?v=EUWVVTY63hc

> you can use too little, so no reason to err in that direction in mass manufacturing

Exactly. The thermal conductivity of air is 0.026 (W/m/K), your average thermal paste (non-metal) is at 2. For manufacturers it's way better to guarantee uniformly meh conductivity by using too much thermal paste than risking air bubbles by using too little. Most manufacturers will lean this way when they don't just use those POS thermal stickers.

Same with average versus silver: silver provides a gain but a limited one, and it's conductive so you have to make very sure not to leak any onto circuits or you risk a short. That's why manufacturers don't bother.

Is there a meaningful impact of the thickness of excessive TIM? I suspect the answer is no given the clamping power of the mount will get the paste down to roughly a consistent thinness even with over-application.

What about any excess TIM off the edges drawing heat away from the heat pipes/cold plate?

Remember that the amount needed differs if you have an IHS (every modern desktop processor) or straight die like in a laptop.

Reply on news.ycombinator.com