Does Thermal Paste Expire ?

You might be wondering if the Thermal Paste that you brought a few years ago will be Expired or not. Well, it may be and may not be expired but yes like everything, Thermal paste also has a lifespan and it can also expire after a certain time.

Does Thermal Paste Expire

Generally, the lifespan of a Thermal Paste varies between 2 to 5 years depending on the Brand and Materials used.

What Thermal Paste is made of?

Thermal Paste/ Thermal interface material (TIM)/Thermal Gel/Thermal Grease consists of two parts: One is the Liquid Matrix which is generally a Polymer(like Silicon, Epoxy, Acrylate, etc.) and the second one is the electrically insulating and thermally conductive filler(Zinc Oxide, Aluminum Oxide, Boron Nitride, etc.) that is present in larger quantities to make Thermal Grease effective. Since the ratio of Filler Material to the Base fluid decides the properties of the Thermal Paste so the Filler Material concentration is kept high(up to 70-80%) to increase its thermal conductivity. 

NOTE: Thermal Conductivity of a Thermal Paste is measured in W/m.k(Watt per Metre Kelvin) where Thermal conductivity is defined as the rate at which the heat is transferred by conduction through a unit cross-section area of a material.

There are different types of Thermal Paste available in the market but the most common ones are Silicon-based due to their low cost and easy application. Metal Oxide filler-based Thermal Paste is also available in the market which offers High Thermal conductivity.  The silver-based thermal compound consists of very small silver particles suspended in Silicon/Ceramic Medium which offers conductivity between 3 to 8 W/(m·K) or more. Metal-based Thermal Paste is highly efficient but it also has good Electrical Conductivity which poses the threat of Short circuits on leakage. 

NOTE: The most efficient and expensive paste consists of Liquid metal(Gallistan- an alloy of Gallium Indium and Tin) as a filler. These are highly efficient but possess the risk of spillage and can not be used with Aluminum sinks due to the corrosion risks. 

How to check if your Thermal paste is expired?

Since Thermal Paste can also expire so it's necessary to check if it is in good condition or not before applying. 

If your Thermal Paste is sitting idle for a long time at a normal temperature in an air-tight packaging then there might be chances that it is still in good condition. To make sure if it is in good condition or not, apply it on a smooth metallic flat surface and if its consistency feels good then it is good to go. But if it comes out to be watery, clumpy, flaky, hard, or dried then it is sure that the Thermal Paste is not in good condition to use so it should be discarded. 

NOTE: If your Thermal Paste is expired and you still want to use it then eject the Thermal Paste and mix the components again such that it becomes consistent enough to be used. 

What measures should be taken while storing Thermal Paste?

To store the Thermal Paste for longer life, the following precautions should be taken:

  • Keep the Thermal Paste Syringe in an Air-Tight bag or container.
  • Before keeping the Syringe make sure that the Piston should not be pulled out more such that it introduces air into the syringe. Air can lead to the oxidization of Thermal Paste. 
  • Keep the Thermal Paste at a normal room temperature and make sure to keep it away from the direct sunlight. 
  • Keep the Thermal Paste in the dark area if possible. 
Why Thermal Paste is necessary?

Heatsinks are generally made up of Copper or Aluminum due to their higher thermal conductivity: 400 W/m.k for Copper and 200W/m.k for Aluminum. The thermal conductivity of Copper and Aluminum is higher than that of Thermal Paste but we still need this because the surface of IHS(Integrated Heat Spreader) is imperfect on microscopic levels, which can trap air and can hinder the cooling capabilities of the processor. The application of a thermal paste fills up those imperfections and improves the cooling efficiency of the Heatsink. 

Does Thermal Paste Expire

NOTE: IHS(Integrated Heat Spreader) is the metallic lid of the CPU. It serves as a heat sink to eject heat from the processor to a CPU cooler and to protect the processor inside. This is the part of the CPU that is still exposed after being installed in a motherboard and is the surface on which thermal paste is applied. 

When should you apply Thermal Paste?

You should apply a new Thermal Paste to the CPU whenever you open or install a new processor. Apart from this, you should also apply a new layer of Thermal Paste if you witness a performance drop due to the increase in temperature. Also, if it's been years since you have cleaned your CPU and applied a new thermal paste then it is recommended to take out the processor and reinstall it after applying a new layer of Thermal Paste on the cleaned IHS. 

We hope this article helped you to know if Thermal Paste Expire. Thanks for Reading!!

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