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AFRL program improves manufacturing process for Air Force communication system components

WRIGHT PATTERSON AIR FORCE BASE -- future air superiority in anti-access area denial (A2AD) environments requires improved network connectivity supporting manned and unmanned teaming as shown in Figure 1. In response, engineers from AFRL's Manufacturing and Industrial Technologies Division (ManTech) completed an advanced communications affordability (ACA) program that significantly improves the manufacturing readiness level and affordability of advanced Gallium Nitride (GaN) Monolithic Microwave Integrated Circuits (MMICs).

Advanced GaN technology provides superior solid-state power amplifiers (SSPA) in V/W-bands. The intrinsic breakdown and current densities of GaN high electron mobility transistors (HEMTs) enable two to five times the output power of gallium arsenide MMICs. GaN HEMT MMIC technology has evolved rapidly over the past decade; however, no high-yield, low-cost V/W-band GaN HEMT MMIC fabrication facility is currently operating. This capability is critical for the U.S. military to have affordable GaN SSPAs for airborne communications systems and other Department of Defense (DoD) applications.

These integrated circuits are processed on 100 mm silicon carbide substrates (wafer) for performance from V through W-band (up to 100 GHz).

Research

ManTech engineers worked with Northrop Grumman Aerospace Systems to execute the program at Northrop's microelectronics facility in Redondo Beach, California. The facility conducts research and produces products for DoD air and space systems.

The manufacturing approaches for the program focused on up scaling the wafer fabrication process from approximately 76 mm to 100 mm diameter wafers in a production-relevant environment. Eliminating unnecessary manufacturing steps and automating other manual steps reduced fabrication cycle times by 43%.

Larger wafer size, improved capital equipment, and implementation of 14 manufacturing improvements over the course of the project reduced production costs by three times and doubled the yield of GaN HEMT MMICs.

Impact

This ACA program demonstrated improved W-band performance and record V-band performance greater than 32 decibel-milliwatts of output power (1.6W) and 10- decibel power gain from 60-64 gigahertz, as shown in Figure 2.

Providing highly reliable, zero-maintenance systems minimizes the Air Force's overall operations and maintenance costs. The GaN HEMT MMICs demonstrated reliable operation under high-temperature and radio-frequency driven accelerated life testing, with a projected median lifetime failure at 200 degrees Celsius junction temperature of over one million operating hours. A long-term operational life test of the GaN HEMT standard-evaluation circuits showed very good stability, with less than 0.5-decibel change in output power after 8,570 hours of testing under nominal operating conditions.

ManTech assessed Manufacturing readiness levels (MRL) several times during the program, and improved from MRL 2 to MRL 6 upon completion. This ensures GaN HEMT MMICs can be produced in a production relevant environment.

Recently, ManTech provided GaN technology to the Air Force's Jetpack program. The Air Force used GaN HEMT MMICs in aircraft communications equipment, allowing fourth generation aircraft to receive information from fifth generation aircraft using the multifunction advanced data link (MADL) and intra-flight data link (IFDL) in an A2AD environment.The jetpack program validated the ability to simultaneously link and translate both the F-35 Lightning II's MADL and the F-22 Raptor's IFDL to a common terminal.

About the Manufacturing and Industrial Technologies Division

The Manufacturing and Industrial Technologies division is responsible for management and execution of the Air Force industrial preparedness programs in manufacturing technology and industrial base analysis.

Technical Point of Contact

Mr. Dilip Punatar
Air Force Research Laboratory
Materials and Manufacturing Directorate
Manufacturing and Industrial Technologies Division

Technical and Media Inquiries

Air Force Research Laboratory
Materials and Manufacturing Directorate
Corporate Communications Office
937-255-0076