Boundary-Defined Power Integrity: Spatial Energy Flow, Mutual-Inductance Topology, and Cavity-Mode Control in Mid-to-High-Frequency PDNs

This preprint establishes Boundary-Defined Power Integrity for mid-to-high-frequency power distribution networks in AI accelerators, Chiplets, and advanced packaging. It reframes the PDN as a spatial energy-flow and relational-closure problem rather than a one-dimensional impedance-target stacking exercise. Core assets include a three-tier time-scale decoupling architecture, the loop-inductance criterion L_loop = L_pwr + L_gnd - 2M_pg, cavity-mode control via non-periodic boundaries, and a pre-registered ablation protocol with IEEE Std 370 de-embedding. No synthetic impedance or sub-picohenry claims are reported. This record is a conceptual and theoretical preprint. No original experimental dataset is reported. It is Paper 4 of the SBE/DSR Structural Substrates track.