Next-generation dielectric materials are designed for bonding heat dissipation components to electrical devices.

While greases and phase change thermal interface materials (TIMs) have been established as the dominant products for thermal management of electronic devices, new demands for certain applications have given manufacturers cause to seek alternatives. Driven by requirements posed by device size and weight reductions, as well as the desire to migrate away from contaminating chemicals while also improving processability, thermally conductive adhesives are seen as viable substitute for traditional TIMs.

Spurred by consumer demand for smaller, high-functioning devices, products such as mobile phones and higher-powered LEDs have seen dramatic decreases in overall footprints in the last few years. But these are not the only applications that have witnessed such a shift, as miniaturization has taken hold in nearly all sectors of electronics including automotive. In fact, automotive electronics is one segment in particular where newer-generation TIMs are gaining momentum.

While auto electronics manufacturers have used thermally conductive adhesives in the past, many of these materials have come with drawbacks. These can include formulations that are silicone-based, which presents contamination risk; requisite cure temperatures that are too high for certain devices; and little process adaptability.

Responding to the emerging needs of manufacturers in all electronics sectors – including automotive – that require robust thermal management alternatives to traditional materials, new thermally conductive adhesives that marry the most desired characteristics with proven performance capability have been developed. These newer-generation TIM adhesives are high-performance dielectric materials designed for bonding heat dissipation components to electrical devices.

Generally epoxy-based formulations, TIM adhesives may eliminate the contamination concern associated with silicone materials. When formulated as a one-component material, processing simplicity is the result, as any mixing is eliminated and application can be achieved via standard automatic dispensing equipment. This also helps reduce costs by streamlining the process and making use of existing capital equipment.

Perhaps one of the most welcome attributes of this new class of materials is the latitude they extend for varying process conditions. With low cure temperatures (in the range of 100°C), manufacturers can incorporate temperature-sensitive devices without the risk of heat-induced damage to other components. But, new TIM adhesives can also adapt to higher processing temperatures if required and many formulations have shown good performance and stability with temperatures as high as 150°C. Depending on the manufacturing methodologies employed, these materials have the ability to be cured in-line alongside other process heat cycles, which further enhances throughput. And, when using an adhesive in place of thermal greases or phase change materials, there is no requirement for clamps or screws to hold the device in place, which is yet another cost and time-saving advantage of adhesives for thermal applications.

It is important to note, however, that all of the advantages of TIM adhesives cannot come at the expense of thermal transfer capability. So, when evaluating these materials, pay particularly close attention to their thermal conductivity as it relates to the requirements for a specific application. Generally speaking, a thermal conductivity of 2.3W/m.K should be sufficient for many of today’s device criteria.

As electronics products feature higher-functioning components packed closer together within a smaller footprint, thermal management solutions must evolve to address the higher heat production of increasingly miniaturized technologies. Newer adhesive formulations are enabling more miniaturized designs and doing so without sacrificing thermal performance. Though greases and phase change materials still dominate the thermal interface materials landscape, new TIM adhesives are providing a viable alternative to these products and doing so in silicone-free systems.

Acknowledgements

The author would like to thank Henkel engineer Wilson Ma for his valuable input.

Jie Bai is a chemist at Henkel Electronics Group (henkel.com); This e-mail address is being protected from spambots. You need JavaScript enabled to view it .