Reducing the effects of the mounting substrate on the performance of GaAs MMIC flip chips

Flip chip technology has been used in electronic equipment for 25 years or more. This is due to the benefits offered by flip chips such as improved interconnect performance, high reliability, and low cost. Increased packaging demands in wireless communications, and military electronics have lead to the use of flip chips for r.f. and microwave components. For instance, GaAs MMIC flip chips at 15 Ghz have been developed. There a few key technology issues which allow the use of flip chip at microwave frequencies. The most important being the use of coplanar transmission lines. The impact of flipping a MMIC chip is examined using finite element simulations and test data is presented for a flipped microwave GaAs MMIC.<>