Low-cost flip-chip process for monolithic microwave integrated circuits and optical components

Flip-chip solder bonding is a method for simultaneously achieving attachmen t and interconnection between electronic components and substrates. It is p articularly attractive for microwave and optical active devices. However, a major stumbling block to demonstrating flip-chip technology for any new or low-volume application is the requirement for whole semiconductor wafers i n order to apply solder bumps to the die bond pads. This makes design itera tion and technology demonstration extremely expensive. This paper describes a flip-chip soldering process suitable for commercial GaAs monolithic micr owave integrated circuits (MMICs), where the MMICs are available only as in dividual dice with conventional gold wire bond pads. The electrical perform ance of active test circuits manufactured using this method is presented, a nd confirms the superiority of flip-chip soldering for attachment and inter connection of microwave devices.