A comparison study of high-frequency performance between ball bonding and ribbon bonding

This paper presents a comprehensive comparison of high-frequency performance between ball bonding and ribbon bonding. In many microwave applications above 10-GHz, ribbon bonding is usually used because of its high frequency and high power characteristics. In general, ribbon bonding with rectangle-shaped wire will provide lower impedance and inductance at higher frequency than round wire, which also achieve the advantages of stable, less deformation, and low loop height. However these results were not made under a fair comparison between ribbon wire and round wire. In this paper, two objective comparisons for ribbon and round wires have been accomplished under the same conditions on their wire cross-section area and surface area. Therefore, three types of bonding wires, 0.5 × 2 mils ribbon bonding, 2 mils round wire ball/wedge bonding, and 0.8 mils round wire ball bonding were measured up to 20-GHz individually, to analyze their high-frequency characteristics on self-inductance, self-resonant frequency (fSR), and insertion loss (IL) with the same cross-section area and surface area conditions. Based on the measurement results, round wire has lower inductance and IL, and higher fSR compared to ribbon wire when they have the same wire cross-section area. As for the same wire surface area, these three parameters were almost identical for both ribbon and round wires due to the skin effect. It clearly demonstrates that the surface area of conductor determines the current carrying ability instead of the cross section area, and dominates the high-frequency performance of a bonding wire. These experimental results have been systematically compared for verification.