What is the best way to apply thermal paste? I find it confusing

Lets back up a bit as understanding the function of thermal paste is really the core issue which then helps understand how to apply it.

Thermal paste fills the microscopic pits in the two surfaces to improve the thermal transfer from the heat source (CPU and if present GPU) and the heat dump (heat sink) it is a very thin layer and doesn’t take much! We want to cover chip die (back part) or the metal case top surface fully. We don’t want excess paste to get onto the chip carrier (green part) or into the socket or logic board of the system (desktop).

So it doesn’t take much! But we want to make sure the corners get paste, we also don’t want to capture air as that will stop the heat transfer.

• So a circle would not be a good shape as you run the risk of capturing air not good!
• Using a spreader painting the surface can risk capturing air as well so not a good idea either. If you slowly fold the heat sink from one side across the chip you give the air a chance to escape that would help!
• An X which goes into the corners could allow some paste to ooze out as we tend to pile up more at the ends of the cross. If we start at the middle and then go to the corners we are more likely to deposit enough to cover the corners without over doing them. The other approach of working from the middle (+) of the edge risks not getting enough into the corners and having it ooze out along the sides.
• Going with a line down the middle could allow some paste to ooze out at the beginning and end of the line if the line is to close to the end and heavy. Likewise the corners and edges may not get enough paste.

So that’s a breakdown of the most common approaches and the risks for each one.

I personally use the X approach starting in the middle going into to the corners making sure not to over load the corners and not piling it too high in the middle as well. Remember! the goal is to cover the chip die not flood the paste to the carrier which can cause issues.

Also surprisingly the newer Intel i-Series chips which have two dies both don’t get paste! only the core chip gets it not the I/O chip! Remember thermal paste can transfer heat to other places you don’t want heated (extreme heat) Thats the case here we don’t want to overheat the I/O die.

Damaged I/O die!

Hint! Practice icing a cake or cupcakes using a piping cone is a great way to understand how to apply the paste!

I hope this gives you the guidance on whats involved.