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42 DESIGN007 MAGAZINE I SEPTEMBER 2025 A RT I C L E by Pa d m a n a b h a S h a kt h i ve l u a n d N i c o B r u i j n i s , M a c D e r m i d A l p h a E l e ct ro n i c s S o l u t i o n s Abstract As power density and thermal loads continue to increase, effective thermal management becomes increasingly important. Rapid and efficient heat transfer from power semiconductor chip packages is essential for achiev- ing optimal performance and ensuring long-term reliability of temperature-sensitive compo- nents. This is particularly crucial in power systems that support advanced applications such as green energy generation, elec- tric vehicles, aerospace, and defense, along with high-speed computing for data centers and artificial intelligence (AI). In these domains, even minor thermal inefficiencies can lead to hotspots, performance degradation, system failures, and significant safety risks, underscoring the need for robust thermal management solutions. Thermal interface materials Beyond Thermal Conductivity: Exploring Polymer-based TIM Strategies for High-power-density Electronics (TIMs), particularly TIM2 materials, play a vital role in facilitating effi- cient heat transfer from the pack- age lid (integrated heat spreader) to a heatsink, cold plate, or other cooling components. This article examines the underlying principles of TIM2 design and performance, including heat transfer mechanisms, material chemistry, dispensing techniques, bondline control, and long-term thermal performance. The focus is on gap fillers, partic- ularly two-part (2K) silicone-based formulations, and their contribu- tions to manufacturing process efficiency, effective heat dissipa- tion, and long-term reliability. Why TIM2 Matters In thermal design, TIM2 refers to a thermally conductive material applied between the exterior of a semiconductor package, typically the integrated heat spreader (IHS), and a cooling component such as a heatsink, vapor chamber, or cold plate. Unlike TIM1 and TIM1.5, which make direct contact with the chip, TIM2 bridges the secondary thermal interface and must accom- modate greater variability in gap size, mechanical tolerances, surface roughness, and contact pressure. The primary function of TIM2 is to fill microscopic surface irregularities and minimize ther- mal contact resistance at both interfaces between the IHS and the cooling solution. In high- power-density systems where effective heat dissipation is critical, TIM2 performance directly influ- ences junction temperature, thermal cycling reliability, and overall device lifespan. A poorly optimized TIM2 layer can force system designers to throttle chip performance to prevent over- heating, undermining the very goal of advanced high-speed, high-power devices. F i g u re 1 : Ty p i c a l T I M 1 , T I M 1 .5 a n d T I M 2 l o c at i o n s i n i nte g rate d c i rc u i t ( I C ) a s s e m b l y. ▼