Why is Thermal Conductivity important?
As electronic equipment advances and technologies progress, modern components like light-emitting diodes (LEDs), EV Batteries, and Semiconductor Advanced Packaging applications are undergoing integration, miniaturization, and increased intelligence. This evolution results in concentrated heat generation, significantly impacting the service life and performance of electronic devices. Thus improving the heat conduction of Thermal Interface Materials (TIMs) has emerged as a critical challenge, urgently requiring solutions to ensure the optimal functionality, longevity, and reliability of electronic equipment.
The Evolution from Traditional to Polymer-Based TIMs:
Electronic devices dissipate heat using heat sinks, and TIMs play a crucial role in facilitating this process. Traditional thermal conductive materials, such as silver and copper, have limitations in terms of weight and flexibility. In response to these challenges, polymer-based TIMs have gained widespread use, leveraging advantages such as excellent processing performance, cost-effectiveness, and low density.
Despite the inherently low thermal conductivity of polymers (< 0.4 W/m-K), numerous strategies have emerged in recent years to enhance the TC of polymer-based TIMs (Figure 1). Their TC is commonly improved by incorporating thermally conductive fillers such as graphene or carbon nanotubes. The challenge, however, lies in balancing the filler content to enhance heat dissipation without compromising processing ability and mechanical properties. Consequently, the pursuit of high-performing TIMs with minimal filler content becomes crucial, particularly in the realm of microelectronics.
To achieve optimal filler content balance, one strategy is to modify the filler surface using reactive chains to achieve smooth flow of the fillers. CAPLINQ provides a wide range of Reactive silicones that enable higher filler content while maintaining proper flowability within the polymer matrix, thereby maximizing thermal performance. This reactive silicones has the ability to make the inorganic filler easier to blend into the silicone binder resin which facilitates filler dispersion.
Among the reactive silicones products, FM0815J is a recently developed reactive silicone trimethoxy silyl designed to increase filler loadings improving performance properties in silicone systems which has the ability to chemically bond to the surface of the inorganic filler thus a more stabilizing the filler dispersion.
Factors affecting the Thermal Conductivity
Moreover, TC also depends on other multiple factors including the thermally conductive filler characteristics, polymer matrix characteristics, microstructure control of fillers, and thermal interfacial resistance, as shown in Figure 1.
Generally, the random distribution of fillers in common TIMs usually leads to a low through-plane TC: 1–5 W/m-K (PTM5000 & PTM6000). Although many techniques have been developed to fabricate paper-like films which show satisfactory in-plane TC: 5-8 W/m-K (PTM7000, PTM7900, & PTM7950), a high through-plane TC >8 W/m-K (HT9000, HT10000, & HT11000) is more desired for some cases in high end applications. Unlike strategies that have been developed to induce filler alignment in the in-plane direction, the methods to vertically align fillers in the through-plane direction are still limited.
Some prior efforts to improve the through-plane TC of polymer composites are on adjusting the orientation of fillers in the through-plane direction and constructing a 3D network structure. These techniques mainly involve the construction of a segregated structure, magnetic fields, electric fields, chemical vapor deposition (CVD)，3D printing, ice-templating and infiltrating, extensive shear force-directed methods, template-directed methods and hydrothermal reduction.
Example of recent polymer-based with advanced filler system TIMs are phase change materials (PCMs) designed by Honeywell, which are driven by an innovative polymer technology, and can be customized to fit diverse product applications and end uses. In addition to phase change materials, we offer a variety of products with high thermal conductivity and high compressibility, including Thermal Gap Pads, Thermal Hybrid, Thermal Grease, Thermal Insulators, and more.
The research and development of TIMs is a continuous process and choosing the right thermal interface material is critical for improving heat dissipation in multiple devices. An application-specific assessment can be conducted to recommend a suitable TIM application. Contact us and our application engineers and in-house thermal experts will help you out with product selection for your application requirements.
