Multichip-on-flex plastic encapsulated MHDI-low cost substrateless manufacturing for microwave and millimeterwave modules

This paper describes Chip-on-Flex (COF) technology developed by Lockheed Martin/GE as a low cost derivative of the LM/GE Microwave High Density Interconnect (MHDI) technology. Cost take-out is being achieved by directly mounting MMIC chips onto a pre-fabricated polyimide flex circuit eliminating the need to procure expensive ceramic or metal substrates. Structural rigidity is provided by molded plastic to encapsulate the back of the chips. A C-Band T/R module is reported as the proof-of-concept demonstration vehicle, with up to 3.5 watts RF output having been measured over 5 to 6 GHz.