Is it necessary to reapply thermal paste for Laptops if the cooler has to be removed once or twice for servicing?

[H.K.]

Hey guys. I had to send my Predator 15 for servicing and they had to open up the thing including the cooler. But that means the thermal paste on both the Cooler and CPU+GPU was exposed for at least 30 mins to a few hrs. My questions to you,
1. Does the thermal paste needed to be reapplied under these situations?
2. Is the electronic display cleaning liquid/spray a valid replacement for isopropyl alcohol or any other thermal paste removing product?
NOTE :    I live in a country where high end thermal solutions are few and far between including thermal paste. There are only one or two thermal paste products available to the consumers, the quality of which may not be the same (could be lower quality) as the one that came with my Predator 15.

[Lady Fitzgerald]

1. Yes. the thermal paste (aka TIM) needs to be replaced anytime a cooler is removed. Not doing so can (actually, most likely will) allow air to be trapped between cooler and the CPU/GPU, reducing the ability of heat to be transmitted to the cooler.

 

2. Display cleaning fluids are too mild for removing TIM. You should be able to get at least a 70% solution of isopropyl alcohol at any drugstore. It's also known as rubbing alcohol. Higher percentages are better but even 70% is better than nothing. 

[tikker]

It's recommendable to replace the thermal paste if it has been on there for a while. before opening the laptop. More so I'd say if you left it out in the open for an extended period of time. If you sent it in however, I assume they did that already for you. The quality between pastes doesn't vary dramatically if you get some of the more common stuff.

I'd try to find some pure >90% IPA, as I don't know what's in the cleaner. I don't like sprays either as it's much easier to use in a bottle. The main point is getting something that has little water/other stuff in it that could, as that needs longer drying times.