Inductive Coupling Emissions between Bond Wires in Integrated Circuits

Abstract: When making an Integrated Chip, there is a process called contacting or bonding. In this process, the circuit is connected to the capsule. As a result, there is interference between the bond wires through inductive coupling. At higher frequencies, the problem becomes more apparent, which means that the role of frequency in interference should be investigated. By using a bonding machine and making our own measurement prototype, measurements were conducted. Bonding wires on PCB's with different layouts made it possible to investigate differences in interference and coupling. The measurements are also compared with values from a simulated model. PCB's were manufactured with different spacings for bond wires located on them. Measurements showed a measurable increase in crosstalk as the spacing decreased. Simulations with a model representing the different spacings yielded simulated values which showed a good accordance with measurements. Efforts to limit the coupling were made using two methods. The first method involved using grounded conducting lines beneath the bond wires. These were routed both parallel and perpendicular to the wires. The second method involved copper lines in a similar fashion to the first method, but placed in a way such that an additional bond wire can be placed on them parallel to the existing bond wires, in between them. While the first method had little effect on the coupling between the wires, the second method using a ground wire arrangement was found to be effective. On average, the crosstalk was reduced by 4.50 dB, 4.82 dB, and 6.16 dB on the different PCB's.