Abstract

Broadband high frequency systems are increasingly utilising MMIC technology to reduce circuit design uncertainties. At frequencies above 6 GHz the MMIC interconnections become critical, bond wire inductances become significant and bond length variations in the assembly process cause significant performance variation. At Marconi Electronic Systems the benefits of solder bump connections to the MMIC are being explored. These benefits include very low inductance, self-alignment and repeatable connections. The technology is also extremely well suited to automatic and semi-automatic production, making multiple channel systems such as phased arrays more cost-effective. This paper is a review of recent work (2-40 GHz) on solder bumped MMIC circuits and covers broadband flip-chip S-parameter circuit interconnect modelling, thermal modelling of HEMT transistors connected by solder bump arrays. Additional layers to the MMT H40 Foundry process have been specially designed to facilitate solder bump connection.