GHz flip chip - An overview

The drive in industry towards more and more wireless communication for various purposes increases the need for packaging for ever higher frequencies. This paper gives an overview of recent activities, presented by companies and universities, at GHz frequencies. The main topic is the chip interconnect, and GaAs flip chip specifically. Flip chip offers some very significant advantages over wire bonding, such as better electrical performance and smoother assembly process. This makes way for lower production costs and allows for low cost high volume production of both consumer and other products. For lower frequencies, this is well documented, and an increase in activity for high frequencies is now seen. If one is to judge by the number of papers presented, it seems that most of the activities are in USA, Europe, and Asia. In Europe, Germany presents the most results, and in Asia, various Japanese companies dominate. However, it is likely that most of the well known telecom and radar companies are actively investigating flip chip for high frequencies, without presenting the results. Papers are mostly concerned with chip design issues, and simulations of various structures. The coplanar chip design appears to be favored, along with non-melting bumps for interconnect.