Electrical simulation of a shielding structure in 3D package

Electromagnetic interference (EMI) has become a remarkable and negligible problem in SiP module. As package tend to higher density and smaller size, the electromagnetic environment become complex and severe. The shortening distance between different devices in SiP enhances the EMI between different devices. Shielding methods in SiP, especially in 3D package, are worth researching. In this paper, a conformal shielding structure with conductive adhesive is researched. The conductive adhesive is coated on the flip-chip dies and connected to ground plane on the top of the substrate. In order to research the shielding effectiveness of this shielding structure, we construct two models in the 3D full wave electromagnetic simulator HFSS, one with shielding structure, and the other without shielding structure. After simulation, we obtain the distribution and the value of the radiation field at 1mm above the flip-chip die. After analysis and calculation, we get the shielding effectiveness of 16–36dB at 1GHz and 20–48dB at 3GHz.