A low cost multichip packaging technology for monolithic microwave integrated circuits

This paper describes a multichip module technology based on highly impermeable liquid crystal polymers (LCPs) to interconnect and package monolithic microwave integrated circuits (MMICs). Because of the low moisture permeability of the LCPs, the packages can be made hermetic without heavy expensive housings can be two to four times lighter and one-fifth the cost of conventional ceramic based transmit/receive (T/R) modules. The LCP material has a low dielectric constant (2.65) and low-loss tangent and is manufacturable using high volume, large-area processing methods that provide very reliable high-performance circuits at low cost. Using flip-chip bonded MMICs attached to a high thermal conductivity, low coefficient of thermal expansion substrate, this innovative technology can meet a variety of commercial, military, and NASA requirements