Effects of grounded-lid apertures for package-level electromagnetic interference (EMI) shielding

A lid is widely used in integrated circuit and package to provide the die protection, heat spreading and warpage control. High-speed signals from a die and traces can be coupled to the lid causing radiated emissions, which usually result in Electromagnetic Interference (EMI) problems. One method to mitigate the emissions is to connect the lid to the package ground by using electrically conductive adhesive. However, some apertures on the grounded-lid are required to be left for package reliability during lid attachment process. These apertures will decrease the shielding effectiveness (SE) of a grounded-lid. In this paper, an equivalent model is used to examine the effectiveness of aperture location, size and number for reducing radiated emissions from the grounded-lid. Both simulation and measurement results are presented to provide fundamental understanding for the design of grounded-lid with apertures.