The Creation of High Thermal Conductivity Thermal Interface Pads Using Graphite Nanofibers

 

Thermal Interface Materials (TIMs) are designed to fill in poorly conducting air gaps between components such as heat sinks and microprocessors to allow for efficient thermal transport and prevent the overheating of critical electronic components. TIMs have come in many forms including thermal greases or pastes, phase change materials (PCMs), solders, and thermally conductive adhesive pads or tapes. Although thermal greases and pastes have the highest thermal conductivities they are usually oily-based so their application is messy, making them difficult to apply in a thin, uniform coat and they are not reusable. Moreover, in applications that involve high temperatures or extensive thermal cycling, the thermal greases have suffered from drying out or voiding from pumping out of the interface which increases the thermal barrier. Pads have become a more common TIM to avoid the difficulties with pastes; however, the thermal conductivity of commercially available pads are significantly lower (typically 2 orders of magnitude) then available pastes and hence do not provide for fast and effective thermal transport.

Our research group has developed a process for generating flexible TIMs using binder, plasticizer and graphite nanobifers (GNFs). GNFs are similar to carbon nanotubes (CNTs) in that they are made entirely of carbon; however, GNFs are significantly cheaper to manufacture, can be grown in a larger range of diameters and lengths significantly longer than CNTs, and have the ability to be highly conductive in more than one direction. Furthermore, with a simple change of growth catalyst and production conditions we can easily alter the direction in which the sheets of graphite orient themselves in GNFs. 

 

Poorly dispersed GNF/binder TIM.
Poorly dispersed GNF/binder TIM.
Properly dispersed GNF/binder TIM.
Properly dispersed GNF/binder TIM.