Analysis and Suppression of Electromagnetic Coupling Interference Through Ceramic Substrate in SiP With Multicavity Shielding

Abstract

Multicavity shielding technology is widely used to suppress electromagnetic radiation interference between multiple chips in system in package (SiP). However, slots formed by the patterned top metal layer of ceramic substrate can lead to electromagnetic radiation leakage into the substrate, thereby exciting resonance in ceramic substrate with high-permittivity. This article analyzes the electromagnetic leakage caused by slots and identifies the ceramic substrate as a coupling path for interfering electromagnetic waves. The primary resonant mode of ceramic substrate, TE ${}_{mn(p+\delta)}$ , is identified as the key factor degrading the shielding effectiveness of multicavity shielding in SiP. Further analysis reveals that the quality factor (Q) of the substrate can be reduced through dimensional and material optimizations, thereby mitigating coupling interference. However, it remains challenging to entirely block the coupling energy. To suppress coupling interference, a novel composite shielding structure based on substrate integrated cavity (SIC) and electromagnetic bandgap (EBG) is proposed. The EBG, constructed along the SIC walls, forms a 3-D EBG through horizontally periodic metal patches and vertically via arrays. Compared to 2-D EBG, this architecture enables multilayer resonance suppression within the substrate. Simulation results demonstrate that the proposed EBG-SIC achieves broadband suppression across 5.73–11.5 GHz within the SIC resonant cavity, and the shielding effect is verified through near-field scan experiments.