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CircuitWorks Thermal Paste

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CircuitWorks Thermal Paste

Thermal compound for heat transfer away from electronics and electrical components

CircuitWorks® Thermal Paste facilitates heat transfer away from electrical/electronic components. This heavy consistency material is thickened with a heat conductive filler to maintain a positive heat sink seal in electrical/electronic equipment.

Heat Sink Grease (CT40-5)

  • Silicone-base
  • Thermally stable from -40°F(-40°C) to 392°F (200°C)
  • Meets MIL-DTL-47113D Type I

Silicone Free Thermal Paste (CW7270)

  • Silicone free compound avoids silicone migration
  • Thermally stable from -99.4°F(-73°C) to 392°F (200°C).  
  • Exceeds MIL-C-47113 for thermal conductivity

Boron Nitride Thermal Paste (CW7250, CW7250KG)

  • Provides maximum thermal conductivity with superior dielectric properties
  • Silicone free compound will not harden or dry out
  • Thermally stable from -99ºF (-73ºC) to 392ºF (200ºC)
  • Exceeds MIL-C-47113 for Thermal Conductivity

Features & Benefits

  • Facilitates heat transfer between circuit components and heat sinks
  • Excellent thermal and dielectric properties
  • Will not dry out, harden, or melt
  • Noncorrosive and nonflammable

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Part # Size Units Per Case

Heat Sink Grease - 5 oz. / 142 g tube

12 blister cards

Silicone Free - 7 g (0.25 oz.) syringe

12 blister cards

Boron Nitride - 3.4 g (0.12 oz.) syringe

12 blister packs
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How does heat sink compound (thermal paste) work?

Thermal paste, also known as heat sink compound or thermal interface material (TIM), is a substance used to improve the thermal conductivity and transfer of heat between two surfaces, typically the CPU (central processing unit) or GPU (graphics processing unit) and the heat sink.

When a CPU or GPU operates, it generates heat due to the electrical resistance in the transistors and other components. To prevent the device from overheating, a heat sink is used to dissipate this heat away from the chip. However, there are microscopic imperfections on both the chip's surface and the heat sink's base that can create tiny air gaps between them. Air is a poor conductor of heat, so these gaps can reduce the efficiency of heat transfer.

Here's how thermal paste works to overcome this problem:

  • Filling in imperfections: Thermal paste is a viscous material with high thermal conductivity. When applied, it fills in the microscopic imperfections on the surfaces of the CPU/GPU and the heat sink. This ensures that there is maximum contact between the two surfaces, minimizing the number of air gaps.
  • Enhancing thermal conductivity: The thermal paste is designed to have a much higher thermal conductivity than air. By creating a continuous layer of thermal paste between the chip and the heat sink, it allows heat to flow more easily from the CPU/GPU to the heat sink.
  • Eliminating air pockets: Air pockets can act as insulators, hindering the heat transfer process. The thermal paste helps to eliminate these pockets, promoting a more efficient transfer of heat.
  • Compensation for surface irregularities: Even if the surfaces of the CPU/GPU and the heat sink appear smooth, they often have microscopic irregularities. Thermal paste, being a malleable material, can conform to these irregularities, further improving the contact area and heat transfer efficiency.

For more information, check out "Repairing & Avoiding Electronic Faults with Thermal Paste".

How do you apply heat sink compound (thermal paste)?

Applying heat sink compound, also known as thermal paste, is essential for proper heat transfer between a CPU (Central Processing Unit) or GPU (Graphics Processing Unit) and its corresponding heat sink. Thermal paste helps to fill microscopic imperfections on the surfaces of both the CPU/GPU and the heat sink, ensuring better thermal conductivity and reducing the chances of overheating. Here's a step-by-step guide on how to apply thermal paste correctly:

Note: Before starting, make sure to clean the surfaces of the CPU/GPU and heat sink with a lint-free cloth and isopropyl alcohol to remove any existing thermal paste or debris.

Step 1: Choose the right amount of thermal paste. Generally, a small pea-sized amount or a thin line along the center of the CPU/GPU is sufficient. Using too much can cause excessive spreading and lead to uneven heat distribution.

Step 2: For most CPUs and GPUs, it's best to apply the thermal paste directly onto the center of the CPU/GPU. If your CPU/GPU has an integrated heat spreader (IHS), apply the paste on top of it.

Step 3: If you have a CPU without an IHS, you can apply the thermal paste directly to the center of the CPU die. However, this method requires more precision and is generally recommended for experienced users.

Step 4: Once you've applied the thermal paste, carefully place the heat sink on top of the CPU/GPU. Make sure the heat sink is aligned with the CPU/GPU, and then gently press it down.

Step 5: Secure the heat sink in place using the appropriate mounting mechanism for your CPU/GPU socket. This could involve screws, brackets, or other fasteners, depending on your system.

Step 6: Avoid twisting or sliding the heat sink after it's in contact with the thermal paste. Doing so can create air pockets and reduce the effectiveness of the thermal transfer.

Step 7: Double-check to ensure that the heat sink is firmly and evenly seated on the CPU/GPU. If it's not making proper contact, you might need to reapply the thermal paste and try again.

Step 8: Reassemble the rest of your computer components, ensuring everything is properly connected and secured.

Step 9: Power on your system and monitor the temperatures to ensure that the thermal paste is doing its job correctly.

Remember, when applying thermal paste, less is often more. The goal is to fill any gaps and create a thin, even layer for optimal heat transfer. With proper application, you can ensure that your CPU/GPU stays cool and performs optimally.

For more information, check out "Repairing & Avoiding Electronic Faults with Thermal Paste".

Is heat sink compound (thermal paste) electrically conductive?

Heat sink compound, commonly known as thermal paste, is electrically non-conductive. Its primary purpose is to enhance thermal conductivity between a heat-generating component, like a CPU or GPU, and a heat sink or cooling solution. By filling in microscopic imperfections and air gaps between the two surfaces, it improves the transfer of heat, helping to keep the component cool.

We design thermal pastes with materials that have low electrical conductivity to prevent any possibility of short circuits or electrical interference when applied between electronic components. This is essential because these compounds are often used in areas where electronic components are densely packed together.

My thermal paste seems like it's getting dried out. Can I re-solvate it?

Try adding VMP naphtha (a common paint thinner) to the compound at approximately 1 part VMP to 100 parts compound. Mix thoroughly to get it back to the consistency required. This is mostly by “eyeball” so you may need a little less or a little more, depending on how dry the material is.

How do I figure out the shelf life of a product?

The shelf life of a product can be found on either the technical data sheet (TDS), available on the product page, or by looking on the certificate on conformance (COC). The COC can be downloaded by going to Once you have the shelf life, you will need to add it to the manufacture date for a use-by date. The manufacture date can be identified by the batch number. The batch code used on most of our products are manufacture dates in the Julian Date format. The format is YYDDD, where YY = year, DDD = day. For example, 19200 translates to the 200th day of 2019, or July 19, 2019. This webpage explains and provides charts to help interpret our batch numbers:


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