The copper conductors are coplanar, 10um thick and 10um wide, separated by 10um. For the volume filament method each conductor is divided into a 20x20 mesh, resulting in 800x800 matrix size. For the surface ribbon method the same mesh is used, but this time only at the surface. The size of the matrix for the latter case is 160x160. Figure 2 compares the series impedance per unit length for the coplanar bars found with the different models.
All techniques are in good agreement for the series resistance of the interconnect.
The main advantage of the surface filament approach is seen when CPU times are compared. It should also be noted that most techniques designed to speed up volume filament calculations can also be applied to the surface ribbon approach. In conclusion, we have shown several surface impedance models, that when used in combination with a surface ribbon calculation, can efficiently and accurately find the series impedance per unit length of multi-wire lossy interconnects. Microwave Theory Tech. , Sept. 1994. Magnetics , vol.