Impact of Gold Wire Bonding Geometries on RF Performance in Ka-Band Microstrip-to-Chip Interconnects: A Comprehensive EM Simulation Study

This paper investigates the impact of ball-bonded and wedge-bonded gold wire geometries on RF performance in Ka-Band (26.5–40 GHz) microstrip-to-chip interconnects through three-dimensional electromagnetic simulations. By varying wire span (D), loop height (H), inter-wire angle (θ), and spacing between wire bonding joints (d) in the V-shaped gold wire interconnect configuration, the effects of bonding wire geometry on insertion loss (IL) and voltage standing wave ratio (VSWR) are systematically analyzed. Results indicate that IL and VSWR generally increase with larger D and H. But for sufficiently low loop heights (or short wire spans), increasing D (or H) improves VSWR due to the trade-off between inductive and capacitive effects, which is further modulated by signal frequency. For wedge bonding, a inter-wire angle of 30° significantly improves VSWR and in-band flatness. Conversely, increasing the inter-wire angle in ball bonding degrades electrical performance. Additionally, spacing between bonding joints on the chip side has negligible impact on IL and VSWR.