The electromagnetic interference (EMI) problems are crucial for system-in-package (SiP) due to the high demand of miniaturization and dense integration. Shielding methods are generally employed to protect SiP from EMI, through assessing the key performance index, i.e., shielding effectiveness (SE). In this article, the SE of a SiP is evaluated by using near-field scanning method. The SEs derived by using maximum near-field values and average near-field values are comparatively analyzed. The difference in near-field patterns of the unshielded and shielded SiPs may incur overestimation of the SE by using maximum field values. Both simulation and measurement results manifest that the gap between SiP and printed circuit board (PCB) will significantly change the radiation pattern of a shielded SiP, and thus has a great impact on the SE, especially when the frequency is above 1 GHz. However, a good correlation is found between the SE based on average near-field and the SE derived from the radiated power. This study has revealed the near-field shielding properties of SiP, which is helpful for building and analyzing the correlation among the SEs measured by different methods, including the near-field scanning, transverse electromagnetic (TEM) cell and reverberation chamber.

中文翻译：

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基于近场扫描的封装系统屏蔽效能分析


由于小型化和密集集成的高要求，电磁干扰（EMI）问题对于系统级封装（SiP）至关重要。通常采用屏蔽方法来通过评估关键性能指标（即屏蔽效能（SE））来保护 SiP 免受 EMI 影响。在本文中，使用近场扫描方法评估SiP的SE。对利用最大近场值和平均近场值得出的SE进行了比较分析。未屏蔽和屏蔽 SiP 的近场模式差异可能会导致使用最大场值高估 SE。仿真和测量结果都表明，SiP 和印刷电路板 (PCB) 之间的间隙会显着改变屏蔽 SiP 的辐射方向图，从而对 SE 产生很大影响，特别是当频率高于 1 GHz 时。然而，基于平均近场的 SE 和源自辐射功率的 SE 之间存在良好的相关性。这项研究揭示了SiP的近场屏蔽特性，这有助于建立和分析通过不同方法（包括近场扫描、横向电磁（TEM）单元和混响室）测量的SE之间的相关性。