Placement Design for a Stacked Die Package With Reliable Wireless Connections

In this article, vertical interconnection implemented as capacitive-based chip-to-chip differential signaling offers crosstalk noise reduction in three-dimensional (3-D) die stacking. To investigate the effects of signal transmission reliability on the 3-D stacked die structure, this article aims at providing the parametric models. The signal and noise properties of capacitively coupled channels are studied using a 3-D electromagnetic field solver to extract the mixed-mode scattering parameters of the differential signal pads. Corner differential arrangements are considered, and their abilities to reject noise are investigated through the proposed parametric models. The exponential decay and generalized exponential decay models are formulated and estimated with the simulated data to assess the transmission quality of the signal. It is observed that there is a nonlinear pattern of the signal-to-noise ratio values related to differential frequency responses for the given pad overlap and the pitch size. The performances of the two models are compared through the root-mean-square error and the mean absolute percentage error for sample fitting as well as for extrapolation prediction. The characteristics of the generalized exponential decay models are also presented and illustrated. The proposed design methodology can be applied to expedite the optimized implementation of capacitive coupling interconnection for a specific operating frequency band.