Developing a via-prototype library for capacitance estimation

The estimation of via capacitance is a necessity for high speed PCB designs because the capacitive loading of signal traces introduces impedance discontinuities, but proves to be a problem difficult to solve using fast calculation techniques, the most accurate approach being numerical field-solving, which requires intensive computational resources. A new technique to control the capacitance of vias in high speed printed circuit board (PCB) design was developed by the authors, called "the via prototype method". The implementation of this method requires a set of models of via geometries with a known capacitance, called "via prototypes", obtained using a high-accuracy analysis technique. This paper present the development of a library of such via prototypes, based on numerical analysis using the software package "IBM Set of Tools of Electromagnetic Field Solver EIP1.1".