REDONDO BEACH, Calif. - Northrop Grumman is advancing diamond-based thermal management for high-power radio-frequency microelectronics under the Defense Advanced Research Projects Agency's (DARPA) Technologies for Heat Removal in Electronics at the Device Scale program (THREADS).

Northrop Grumman announced that it had received a $7 million DARPA contract for a second phase of its work, which the company says will seek to increase the power density of its diamond-enhanced microelectronics by more than three times.

The technology is intended to address a fundamental limitation in high-power RF electronics: removing heat from increasingly small semiconductor devices. Excess heat can limit RF output power, reduce efficiency, and shorten device lifetime, constraining the performance of radar, electronic warfare, and communications systems.

THREADS

DARPA established THREADS to address thermal-management challenges at the transistor level. The program focuses on reducing thermal resistance within RF devices while maintaining electrical performance and on moving heat away from high-power transistors without degrading RF performance. DARPA's stated program objectives include an eightfold reduction in transistor thermal resistance and an RF power density of 81 watts per millimeter in high-efficiency, reliable X-band transistors and power-amplifier test devices.

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DARPA reported in June that THREADS Phase I demonstrated approximately a fivefold increase in RF power density compared with state-of-the-art devices across the program. The agency said the Phase I results also demonstrated the required device lifetimes for defense applications. DARPA is pursuing additional increases in power and thermal performance in Phase II.

Northrop Grumman says its own Phase I work increased the power of its diamond-enhanced devices by 3.3 times. The company now plans to increase power density by more than three times again during Phase II. The company says the approach could enable higher-power RF transmitters for military communications, satellite links, and other applications while reducing the space required for the electronics.

Diamond is being investigated as a thermal-management material because of its high thermal conductivity. This engineering challenge is especially important because RF semiconductor technologies generate more heat at higher power densities. Removing that heat near the transistor can help prevent thermal limitations from offsetting improvements in the device's electrical performance.

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Thermal management

The THREADS program is focused on device-scale thermal management rather than relying solely on larger external heat sinks or cooling systems. DARPA says the objective is to increase RF output power without increasing the system's size, weight, or complexity. Potential applications include longer-range sensing, electronic warfare, communications, and other RF systems.

Public contracting records identify Northrop Grumman Systems Corp. as the recipient of contract FA2385-24-C-B003, awarded 1 Dec. 2023, under the THREADS solicitation HR001123S0013. The cost-plus-fixed-fee contract has a potential value of approximately $22 million and a potential completion date of 1 Feb. 2028. Public records show multiple subsequent actions, including a $2.4 million option exercise in September 2025. The contract record also identifies subcontract work involving Stanford University, the University of Texas at Dallas, and the University of California, Los Angeles.

The distinction between Northrop Grumman results and the broader THREADS program results matters. Northrop's reported 3.3-times improvement describes its own Phase I work, while DARPA's approximately fivefold increase describes results across the THREADS program. Those figures should not be treated as measurements of the same device or technology.

The Phase II effort will be worth watching for more specific performance data, including RF power density in watts per millimeter, thermal-resistance measurements, device operating temperature, semiconductor architecture, and reliability. Those figures would help establish how the diamond-based approach compares with conventional thermal-management techniques used in high-power RF semiconductor devices.