Hot-via interconnects: a step toward surface mount chip scale packaged MMICs up to 110 GHz

Two new techniques based on the RF hot-via concept have been developed for use in chip-scale packaged (CSP) MMICs. The first one utilizes backside bumps for die attach onto a substrate carrier; excellent RF performance has been achieved on both active-, and passive MMIC devices up to 110 GHz. The second technique is based on direct soldering of the MMIC backside interconnects onto low cost substrate carrier (RO4003), making it ideal for a wire-bond free full surface mount approach. To the author's knowledge this is the first demonstration of such die attach-, and packaging techniques for MMICs. As application examples, experimental performance results obtained with both techniques, are presented for transmission lines, and broadband 30-GHz GaAs PHEMT amplifier MMICs.