Electrical characterization and analysis on the via-solder ball structure

With the increasing of operating frequency, parasitic parameters of packaging have significant effects on the performance of integrated circuits. Signal paths in packaging bring great transmission loss, especially discontinuous interconnections. In this paper, de-embedding methodology is used to extract S-parameter of via-solder ball structures. A typical test structure is designed, which consists of two 6-layer organic substrates that are vertically stacked by employing BGA interconnections. The results show that the insertion losses of via-solder ball with the diameter of 500μm and 600μm are below 3dB when frequency increases up to 10GHz. But for 760μm via-solder ball structure, the frequency range of 0 to -3dB insertion loss is DC to 7.5GHz. It can be seen clearly that the insertion loss increases with the increase of the diameter of solder ball. Through this work, we have a better understanding of the electrical characteristics of via-solder ball structure. And it can provide a direct reference for signal transmission path design.