Superior Thermal Conductivity

Ultimately, the value of a TGP is determined by its ability to provide higher thermal performance when compared head-to-head with solid conductors of equivalent size and CTE. Figure 3 compares the CTE of various electronic materials and TGP to their effective thermal conductivity. TGPs offer a peak effective isotropic thermal conductivity equal to or greater than 1200 W/m.K, which is superior to that of all known composites and comparable to mid-grade polycrystalline diamond, which also exhibits a significantly lower CTE. Depending on the size of the TGP, the thermal conductivity can be up to 3 to 10 times higher than with conventional material systems.

Other advantages include the ability to handle high heat flux, up to 350 W/cm2, in a flexible form factor that exhibits greater tolerance to body forces, up to a six g-force demonstrated.

This performance is achieved using low-cost materials and fabrication techniques. The increased conductivity enables electronic designs to handle increased power in a smaller space – a valuable advantage when designing for aerospace and military applications.

Application Advantages

Figure 5. Increase in Module Current for an Equivalent Die Count.

Today, TGP technology is proving its value by providing higher performance compared to solid conductors of equivalent size. For example, analysis was conducted on a typical power module with and without TGP technology. Figure 4 shows a comparison of the internal temperatures as TGP technology is applied. A standard module will have a maximum die temperature of 160°C. When TGP is applied under the die, temperature reduces to 120°C. This temperature is further reduced to 97.3°C when another TGP is applied under the substrate. Overall, this equates to a 50% reduction of the internal thermal resistance, θj-c, of the module. The advantages of this are significant:

  • Increased Performance: Figure 5 shows that the current in the module could be increased by 40%.
  • Lower Cost: Rather than increasing the current, the better cooling can be used to reduce the WBG die count by pushing the operation of the WBG devices. Analysis shows that this can be reduced by approximately 30%. This is a tremendous cost savings, especially since WBG dies constitute most of the module costs.

Thanks to the DARPA-supported TGP program, a cost-competitive CTE-matched vapor chamber technology has been developed that offers significant performance advantages relative to solid conductor alternatives. Conventional copper powder and copper foam wick structures can be utilized to provide higher levels of performance and reduce sensitivity to operating conditions (e.g., heat input, temperature). Both research work and practical application have firmly established the utility of TGP technology.

The thin, flat form factor of the TGP makes it ideal for directly mounting electronic devices for improved thermal dissipation and reduced interface resistance. Design engineers can customize the CTE for attachment to devices to provide thermal control for electronic components in satellite radiator panels, target acquisition systems, remote wing electronics and navigational avionics applications.

Compared to traditional cooling methods, TGP material systems provide a high-performance thermal management solution today that can handle the demanding aerospace and defense challenges of tomorrow.

This article was written by Nelson Gernert, Vice President, Engineering and Technology; Mark North, Engineering Group Leader of Research and Development; and Gregg Baldassarre, Vice President, Sales and Marketing; Thermacore, Inc. (Lancaster, PA). For more information, Click Here.