56 not only to enable module repair but also to make the TIM itself recyclable – an important breakthrough because conventional TIMs, whether gap fillers, adhesives or gap pads, are generally not recyclable and cannot be reused. Truly reworkable, high-performance TIMs are achievable, but only if they are treated as a shared design challenge from the beginning. This requires close collaboration between pack design engineers and material developers because reworkability is not something that can be added later without consequence. There will be trade-offs in material performance, and the key is to understand those early so that the final design can strike the right balance between thermal performance, manufacturability and serviceability. Several such materials are now available for EV battery applications. Reworkability is system-level design challenge. Rather than effortless removal under all conditions, the aim is controlled, predictable debonding without damaging components. In pursuit of longevity In striving for efficient use of material resources, longevity is just as important as repairability and recyclability. Developers are being asked to guarantee performance for far longer than they can physically test – often 15 years – so a variety of other predictive approaches are employed. Combining decades of experience with accumulated test data, accelerated stress and ageing tests, plus intelligent digital simulation, is a powerful means of confirming long-term performance. With accelerated tests, it is important to note that they are meaningful only when they reflect real failure modes, such as loss of contact pressure or interfacial degradation. By pairing this with stable formulations and conservative design margins, credible, physics-based confidence in long-term performance can be instilled. Further, offering guidance on key factors that can influence performance under assembly conditions – such as surface contact ratio and recommended maximum compression levels of the material – supports customers in designing their assembly conditions and enables more robust system-level longterm reliability validation. Experience with power electronics is particularly helpful in ensuring longevity because TIMs used in these applications are exposed to operating temperatures significantly higher than those found in batteries, often above 150 C. Mechanical properties such as adhesion can still depend on specific load conditions, but here also materials are typically designed with higher requirements in mind. Performing accelerated ageing tests together with customers is still important, but for silicone-based materials in particular, the thermal stress placed on them in battery systems is usually not the limiting factor. Often, the discussion is less about whether the material can survive 15 years and more about which tests should be performed, how long they should run and what the validation strategy should be. In second life applications, such as energy storage, battery modules are often rebuilt or integrated into different systems where they are subjected to less-demanding operating conditions than in automotive use, for example lower vibration, and where their service lives may be longer still. Liquid-cooled electronics Liquid cooling has become the standard in all but the smallest of EV batteries, while in data centre applications it is moving from racks that hold processing systems to the chips themselves. This is also beginning to be used in very highpower EV inverters, although not in the same way as in data centres. Direct-tochip cooling relies on the same core TIM principles as other advanced cooling approaches, but its demands are far less forgiving. Because these systems operate at extremely high local heat flux, they require tightly controlled bond-line thickness, excellent cold plate flatness and precise mechanical loading. Even small variations can amplify hotspot severity, increase thermo-mechanical stress and challenge package reliability. Direct-to-chip cooling, therefore, raises the stakes for TIM performance, turning what is often a material choice into a full-system design issue. As cooling moves closer to the SiC die, the TIM’s role shifts from bulk heat conduction to precision interfacial engineering. Here, ultra-thin bond lines, void-free contact, stress mitigation and reliability under fast thermal transients become critical. July/August 2026 | E-Mobility Engineering Conventional TIMs, including gap pads used in electronics, are not usually recyclable, but thermoplastic materials are (Image: KERAFOL)
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