Thermal interface material (TIM)

Thermal Interface Materials (TIM) are used to enhance heat transfer away from critically hot components in electronics products.

Poor thermal management leads to more than 50% of electronic failures - and the failure rate increases exponentially as temperatures rise. Performance is also hampered by lacking thermal management. Typically, high-end processors and graphics controller are limited by their temperature and much effort is put into installing large cooling fins, fans, liquid cooling etc.  

A main driver for developing better TIMs is therefore the need for larger heat flow away from the device, for better performance, longer lifetime and better reliability. There is an escalation of power density in electronic devices: consumers want higher performance, which is driving power consumption up, within a smaller device footprint area. This trend has turned efficient heat removal into a crucial issue for progress in the electronic industry in general, and information, communication and energy storage technologies specifically (IDTechEx, 2016).

What is TIM?

A thermal interface material (TIM) is used to enhance heat transport from one surface to another, within a heat path, for instance from a hot processor surface to a heat sink. A TIM is required to fill the isolating air gap created between two hard surfaces, due to the micro-scale roughness on the hard surfaces, which is simply too large a thermal barrier for even modest heat transfer. The degree of heat transfer you achieve depends on the performance of the specific TIM material applied, together with the interfacial resistances.

Heat transfer, -conductivity and -resistance

Bulk conductivity (measured in W/mK) and contact resistance (measured in °C/W) are elements of overall thermal performance when comparing TIMs. Bulk thermal conductivity is a measurable material property, whereas thermal resistance is a measurement of heat transfer across a construction of interfaces, i.e. a system property. This means there are more parameters playing an important role than conductivity alone, such as a TIMs ability to wet a hard microstructure surface. Ideally a TIM should fully wet the surface, displacing the air and filling the microscopic voids. In short: The interfacial resistances depend on the surface characteristics of the mating surfaces and the ability of the TIM to flow into surface features and form a void-free and non-filler-depleted TIM layer at the interfaces.

Therefore, a modest bulk thermal conductivity TIM may exhibit a lower thermal resistance than a high conductivity TIM with a large interfacial thermal resistance. High thermal conductivity becomes much more important for thick grease applications or gap fillers where the heat must travel further through the TIM.

CondAlign technology in TIM

In most cases, it is the through plane, or z-direction, performance of TIM that matters: heat should be transferred out and away to the opposite surface – not sideways. This is enhanced with the anisotropic materials based on the CondAlign technology, due to the conductive pathways between the two surfaces.

Another advantage of the lower particle loading is that the material better retains its original properties, such as softness and wetting capabilities. The efficient use of the particles, allowing a lower loading also saves cost compared to random (traditional) particle distribution.

This illustrates three main advantages of TIM-materials based on the CondAlign technology:

  • An anisotropic character of the material, transporting the heat in the direction from one surface to the other.
  • Potentially better wetting of the surfaces and lower interfacial resistance between the TIM material and the hard surfaces, and thus better overall heat transfer.
  • More efficient use of the conductive particles, achieving a similar heat conductivity with less particles, or better conductivity with the same loading.

CondAlign has demonstrated up to 100% improvement in thermal conductivity, with the same particle type and loading. This improvement is higher when the particle loading is lower.

Benefits achieved with the CondAlign technology 

The benefits of better TIM materials can be vested in several ways, or as a combination:

Extended life time and improved reliability, due to reduced component temperature.

Thinner, more compact electronics, due to reduced footprint enabled by more efficient cooling.

Higher performance at a lower complexity and/or price. Cooling is often a limiting factor of high-performance electronics. Some users are willing to accept a much higher cost for a CPU that offers a small percentage improvement performance. Instead, improving the cooling may allow running the same processor harder.

Lower production cost: The TIM is part of a cooling path; better TIM, less requirements for the next step, i.e. a smaller fin or a cheaper fan.

Elimination of the need for more costly methods: In some cases, the fan may no longer be necessary, liquid cooling can be replaced with simpler methods, or a simple glued cooling fin may replace complex mechanical clamps.

TIM types and markets

TIM can be classified in several submarkets, such as thermally conductive pastes, gels, greases and liquids, elastomeric pads, pressure sensitive adhesive (PSA) tapes, solders, phase change materials, liquid metals graphite, compressible interface materials and some more types. The TIM types that can currently be realized with the CondAlign technology are elastomeric pads and Pressure Sensitive Adhesive (PSA) tapes. These types together represent between 50 and 55% of the current global TIM market, which is estimated to reach approximately US$2B in 2021 and $3B in 2025 (IDTechEx, 2016).  

Market entry and collaboration

CondAlign does currently not plan to become a major manufacturer of TIM materials. Our business model is to license the technology to major brands that want to incorporate the technology into their production lines.

Soon your computer will be cooler, cheaper or faster, thanks to CondAlign technology!