Additive Integration of a Bare Die High-Power Microwave Amplifier Using 3-D Printed Interconnects

This work presents a novel exploration of the performance and reliability of 3-D printed interconnects for high-power radio frequency (RF) and microwave applications. Material studies are performed to validate aerosol-jet printed (AJP) interconnects under high-power direct-current (dc) and RF excitation before demonstration in the additive integration of a 19-W high-power amplifier (HPA). First, printed interconnects of various widths are tested under continuous-wave (CW) dc conditions, with traces as narrow as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50~\mu $</tex-math> </inline-formula>m shown to support loads of up to 25 W. Then, printed interconnects are tested at 10 W under pulsed RF conditions of varying pulsewidth and duty cycle. Thermogravimetric analysis (TGA) is used to optimize thermal sintering of the silver nanoparticle printed interconnects and minimize deltas due to part failure or further sintering under high-power loads. Finally, a bare die microwave monolithic integrated circuit (MMIC) HPA is integrated using AJP conductors and novel airgap AJP dielectric filets. Small-signal measurements show about 20-dB nominal gain and 15-dB nominal return loss throughout the 1–22-GHz band of operation, while large-signal measurements show about 19-W peak output power at about 39% power-added efficiency (PAE); excellent results compare favorably versus a wirebonded equivalent and represent a significant improvement over the previous literature.