Study on a Conformal Shielding Structure With Conductive Adhesive Coated on Molding Compound in 3-D Packages

With the continuous improvement of system integration, 3-D packages are becoming effective solutions for lighter, thinner, shorter, and smaller electronic products. Meanwhile, packaging engineers are faced with serious signal integrity challenges. Especially significant intrasystem electromagnetic interference (EMI) problems are aggravated for shortened distance between noise sources and sensitive circuits. In this paper, we present a conformal shielding structure with conductive adhesive coated on molding compound to improve the intrasystem EMI problems in 3-D packages. Three groups of die-stacking samples with different coupling mechanisms are fabricated to evaluate the shielding effectiveness. By comparing the noise isolation of the samples with and without shielding structures, we can clearly see the shielding capability of the conformal shielding structure. The measurement results indicate that the near field coupling noise isolation has significantly improved with the shielding structure. Compared with traditional methods, the conformal shielding structure can realize a cheaper, thinner, lighter, and more flexible shielding. It would be an effective shielding solution for suppressing near field radiation in 3-D mixed signal or RF/Microwave packages.