Differences between Silicone-based and Non-silicone Thermal Interface Materials (TIMs)?

In recent years, the risk of overheating, which can lead to reduced performance or even fire and explosion of electronic devices is alarming. Thermal management is essential to maintain such electronic devices operating within their specification. There has been a growing debate about non-silicone and silicone-based thermal interface materials. But how do these materials truly compare in terms of performance, durability, and usability? In this article, we define the characteristics, advantages, and disadvantages of both silicone-based and non-silicone TIMs to help you make the best decision for your thermal management needs.

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Thermal interface materials – TIMs

For the optimum performance and better reliability of a device, it is important to dissipate heat ef?ciently from the device during its normal operation. That is why thermal interface materials (TIMs) were born. TIM plays a signi?cant role in electronic packages to enhance the heat transfer between contact surfaces. There are a lot of kinds of TIMs on the market. One key factor in choosing a suitable TIM is the composition of the material depending on the application and the desired thermal conductivity. As modern technologies and materials are created, the precise formulation and composition of a thermal interface material may also change over time.??

To know more about how to choose the suitable TIMs to enhance the performance of the PCB, you can refer to this article: Basic Guide to Choose TIMs

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Silicone-based thermal interface materials

Silicone-based TIMs are broadly used in electronic devices. Silicone is a class of synthetic material based on a polymeric siloxane backbone containing silicon, and oxygen atoms attached to the silicon atoms. It is categorized as elastomers, ?uids, or resins depending on the range of crosslinking. Silicone resins are highly crosslinked structures, and at room temperature they can be either liquid or solid.?

Pros of silicone-based thermal interface materials:

• High thermal conductivity: Heat transfer primarily occurs through vibrations of atoms called phonons. While the base polymer in silicone TIMs is a siloxane chain that has strong Si-O bonds, so they efficiently transfer these vibrations along the chain, allowing for efficient heat conduction. That is why Silicone-based thermal interface materials offer higher thermal conductivity compared to some non-silicone alternatives.?
• Wide temperature range: Silicone polymers possess strong silicon-oxygen (Si-O) bonds. These bonds are highly resistant to breaking down at both high and low temperatures, allowing the material to maintain its structure and function across a broad spectrum.?
• Excellent compressibility: The siloxane backbone has organic groups attached to the silicone atoms that have weaker bonds than the strong Si-O bonds, so they provide some flexibility to the structure. Therefore, the silicone backbone can bend and flex to squeeze into microscopic gaps, even surfaces and large dimension variations. This ensures optimal thermal contact and improved heat dissipation.

Cons of silicone-based thermal interface materials:

• Outgassing: This phenomenon is the release of volatile gases when silicone based TIMs are exposed to elevated temperatures and/or low atmospheric pressures. This can be a concern in sensitive electronics applications, optical components, particularly aerospace applications where outgassing is accelerated due to reduced pressures and may also cause problems within sealed cavity packages.?

• Electrical conductivity: While considered insulators at room temperature, some silicone based TIMs can become slightly conductive at high temperatures because silicon electrons can break loose from the silicon covalent bond. Electrical conduction is enabled by their movement across the lattice. As a result, caution must be exercised to avoid short circuits when employed in applications with exposed electrical connections or sensitive circuitry.?
• Pump-out: Most silicone TIMs are not just pure silicone; they contain silicone oil as a base component. Under pressure from the clamping force holding the heatsink in place the silicone oil within the TIM can get squeezed out of the interface gap. This reduces the amount of TIM material in contact with both the component and the heatsink, hindering effective heat transfer.?

Prostech offers high-performance silicone-based TIMs for superior heat transfer and extended product life. Our experts provide tailored solutions to suit every application, overcoming the limitations of non-silicone TIMs to meet all your production needs. Contact us to discuss and receive consultation!

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Non-silicone thermal interface materials

Silicone-free TIMs are formulations that do not contain silicone compounds. Instead, they are typically based on non-silicone polymers, such as acrylics, polyimides, or ceramics,… ?

Silicone-free thermal interface materials are emerging as a new choice of thermal interface materials for industries for the silicone-sensitive devices in many applications, such as optical, medical, and sensor devices, preventing manufacturers from using silicone-based materials.?

Pros of non-silicone thermal interface materials:

• Low outgassing: Non-silicone TIMs are not built using silicone polymers. As a result, they do not have the same chemical structure with low molecular weight siloxanes attached to the backbone. That is why non-silicone TIMs outgas minimally, minimizing the risk of contamination or degradation of nearby components.?
• Electrical Insulation: Certain materials used in non-silicone TIMs inherently possess good electrical insulating properties, even at elevated temperatures. They often have minimal conductive pathways within the material. This reduces the risk of leaking currents at evaluated temperature. But it is important to note that not all non-silicone TIMs are created equal regarding high-temperature electrical insulation.?

Cons of non-silicone thermal interface materials:

• Lower Compressibility: Many non-silicone TIMs utilize materials that are inherently stiffer or less flexible than the silicone polymers used in silicone based TIMs so they may be less compressible, which makes it difficult to achieve optimal surface contact and remove air gaps between the heat source and heat sink.?
• Become hard after long-term exposure to heat (elastomer): After long-term exposure to heat, the crosslinking reaction will occur at high temperature. The crosslinking will cause the elastomeric part to become hard. The crosslinking reaction occurs due to free radicals produced by heat. For this reason, after thermal aging, elastomeric non-silicone TIMs showed brittle-like behavior, which will have an impact on the performance and reliability of the device.

See TIMs products

Characterizing thermal interface materials (TIMs) is essential for ensuring efficient electronic applications and timely product launches. Silicone-based TIMs excel in thermal and mechanical stability at high temperatures, making them ideal for demanding environments. Conversely, non-silicone TIMs are better suited for applications prioritizing electrical insulation, offering enhanced performance and reliability. Additionally, for silicone-sensitive devices, non-silicone TIMs are the preferred choice to avoid compatibility issues.

The choice of the appropriate thermal interface materials depends on the specific requirements of the application and environmental conditions. Each type of material offers its own advantages and is suited to different demands during the manufacturing and usage processes. With many years of experience in the industrial material, Prostech is ready to assist customers in selecting the right materials and providing integrated solutions for production lines to optimize manufacturing efficiency. Contact us for free consultation!