A Gold Bump Flip-chip Interconnection Structure for Face-up MMIC Assembly in RF Front-end Modules

Flip-chip bonding is currently the preferred process for RF front-end module chip assembly. This paper proposes a flip-chip interconnection structure based on the gold bumps for the face-up monolithic microwave integrated circuit (MMIC) chip. The vertical interconnection based on the quasi-coaxial structure on the chip has good RF performance. The MMIC chip can be well grounded through multiple gold bumps while ensuring the mechanical strength after assembly. In order to verify this scheme, a prototype of a MMIC chip on a ceramic substrate with the gold bump flip-chip interconnection structures has been designed, fabricated and tested. The tested results show that the insertion loss of the vertical interconnection structure was 0.2 dB at 12 GHz, which can be used up to 18 GHz for the high-density and high-performance RF front-end modules (FEMs).