Is grease/oil on thermal pads harmful?

Question

I have a Samsung 970 Evo NVMe SSD. These drives usually tend to run hot.

My motherboard is a MSI X570 MAG Tomahawk. I used the heatsink that came with it onto my ssd.

I decided to try another heatsink to see if I could get better cooling performance. When I removed the heatsink, I saw some grease-like substance onto the thermal pad.

Its not even a month had passed since I used my new build but was shocked to see some grease like substance appear.

I was not sure if it was intended to be there in the first place as I was not the one who installed the Motherboard NVMe heatsink onto my NVMe SSD but consulting from other people, they say it is oil.

From what I read, having oils in the thermal pad may be a sign that the thermal pad is of poor quality as the thermal pad deformed in shape (turning into oil) which then results in bad or no contact with the device that is intended to be cooled. If oils continue to accumulate, they may eventually leak and cause a short which in turn, fry my computer.

I do think that this is oil because judging by the appearance and location of this substance, it is located at where the controller and at the NAND flash chips are placed. Different NVMe SSDs will have different placements of NAND Flash chips and controllers, so it looks to me that the substance made an imprint of the said components on where it was placed along the thermal pad. Since these components both get hot, then it becomes evident that grease/oil starts forming onto the side where the thermal pad makes contact with these components.

Also I don't recall needing to apply any substance when installing anything on top of a thermal pad. AFAIK you just slap it onto a surface when you're ready to place it. I can only therefore deduce that it is oil that formed due to heat and not some pre-applied special lubricant that MSI (the manufacturer of the board) applied.

So I should stop using the NVMe SSD heatsink of my motherboard because it forms harmful oils in the long run that can potentially leak if it accumulates too much?

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Update: The substance may actually be Silicone gap filler. Do not let it get to your eyes. If it gets to your eyes, you would need to surgically remove it. Being on the safer side of things, I would advise anyone who experience this to stop using the NVMe SSD heatsink and just get another one that doesn't leak any oil on the thermal pad. Don't forget to wash your hands thoroughly after handling.

Answer 1

Not really.

Thermal pads contain silicone oil. Silicone oils are excellent electrical insulators and have a good heat-transfer and thermal stability. It can melt silicone products, but those aren't usually in hardware yet. On wetware it has the following effects:

Inhalation - A single exposure may cause the following adverse effects: Headache. Nausea, vomiting.
Central nervous system depression. Drowsiness, dizziness, disorientation, vertigo. Narcotic
effect.
Ingestion - Due to the physical nature of this product, it is unlikely that ingestion will occur. Aspiration
hazard if swallowed. Entry into the lungs following ingestion or vomiting may cause chemical
pneumonitis.
Skin contact - Repeated exposure may cause skin dryness or cracking.
Eye contact - May be slightly irritating to eyes. May cause discomfort.

Pads are used to fill larger gaps between component and heatsink than paste can fill. Make sure to use ones that conduct enough heat and are thick enough to fill the gap without compressing too much (more than 30%). They last about 5 years.