Experts: Andrea Battisti, Urs Burckhardt, Steffen Kelch, Martin Zäch (Sika Technology AG)
Thermal interface materials are materials that have high thermal conductivity but do not conduct electricity. These materials are used in the electronics industry in particular and represent a key element of the transition to e-mobility. They are therefore of great importance for Swiss automotive suppliers, even if the market volume tends to be small.
Picture: Sika Technology AG
Thermal interface materials, or TIMs for short, are materials that have high thermal conductivity but are also electrical insulators. Producing such materials is challenging because naturally occurring materials are usually both thermal and electrical conductors. Generally, good electrical conductors are also good thermal conductors – and vice versa. Thus, thermal interface materials are materials in which thermal and electrical conductivity have been decoupled from each other. This is achieved by taking a carrier material that has very limited electrical conductivity and combining it with solid particles that dissipate heat. Such materials are available as pads, tapes, potting resins, adhesives and sealants.
Thermal interface materials are used in the automotive, electrical and electronics industries, as well as in medical technology. The largest market segement is currently the production of electronic devices and battery modules.
One large and rapidly growing market is e-mobility, which requires a large number of high-performance batteries. TIMs are used in the construction of electric vehicles, especially at the interface between the battery and the cooling system. Energy-storage systems in private and public buildings represent another rapidly growing sector. The importance of TIMs for the storage of electrical energy is set to increase further, given the steadily growing importance of renewable energies in energy generation.
Thermal interface materials play an important role in the thermal management of electrical systems. They ensure that components do not overheat while conducting electrical current. In battery design, the trend is towards higher integration with fewer components overall. In addition, ever more components are being bonded. This gives TIMs a key role in process simplification and cost reduction for battery manufacturing.
Switzerland is an attractive location for the automotive supply industry. In this respect, materials for the production of battery modules represent a rapidly growing market segment. Therefore, TIMs are of great importance for the domestic industry. This opens up opportunities for Switzerland as a research location. These encompass new battery designs and cell technologies, as well as research into the basics of thermally conductive materials. TIMs offer society an opportunity to aid the electrification of private transport and the storage of electrical energy, thus helping to achieve sustainability goals.
The challenges in developing new TIMs and improving existing ones reside firstly in changing their properties so that they are easier to mechanically process and inject. Researchers are also trying to reduce curing times for these materials, in order to shorten production cycle times. Secondly, research is being conducted on materials that combine high thermal conductivity with high elasticity, such that they remain stretchable and can thus compensate for differences in the thermal expansion of components. This is particularly important for adhesives used in lithium iron phosphate (LFP) battery cells (see Showcases life cycle of a battery) .
At the end of their service life, batteries have to be disassembled into their individual parts for reuse or recycling (see Showcases life cycle of a battery). This is also a challenge for TIMs. Although reprocessing is not yet the main focus, a basis should be developed in the next few years that enables full circularity for batteries. The ongoing discussion on EU regulations to implement aspects of the circular economy (the Right to Repair Directive) shows that recyclable TIMs are likely to become more important in the coming years (see article sustainable adhesives and sealants).
At present, there are no regulatory or societal barriers to the development of thermally conductive insulating materials. However, there are regulatory headwinds for the battery industry as a whole. These include the threat of lithium being classified as a hazardous material. Such classification could hinder or delay investment within the European Union’s sphere of influence.
Switzerland is currently among the top 10 countries worldwide in the field of TIMs (along with the USA, Germany, China and Japan). In order to guarantee that this remains the case, more funding is needed for materials research in the context of renewable energies. However, funding must occur in such a way as to ensure that the research is internationally integrated. This is the only way to guarantee competitive energy research.
