Breakthrough Packaging Level Shielding Techniques and EMI Effectiveness Modeling and Characterization

Electronic handsets have been rapidly miniaturized in form factor and developed with highly integrated functions, more complexity, and significantly improved performance. Within high density radio frequency (RF) modules, electromagnetic interference (EMI) issues such as unwanted cross-talk among the RF modules in mobile devices, cause electrical performance shifts, and make the modules more susceptible to electromagnetic compatibility (EMC) failures. All of these have raised considerable and critical challenges to RF design, which lead to a greater number of design iterations, prolonged design cycle times, and additional costs in a highly competitive market place. EMC has to be addressed during RF module design and package assembly by minimizing EMI radiation, reducing coupling paths, designing proper shielding, and grounding. The principle of EMI shielding is known as Faraday cage. This paper presents an overview of package level EMI shielding, where a metal layer is applied to partially or completely enclose a package in order to reduce the amount of EMI energy escaping into the external environment and also limit the EMI radiation that can penetrate into the package. Various EMI shielding techniques are compared and contrasted in terms of materials, process complexity, manufacturability, cost and EMI shielding effectiveness. Near-field EMI measurement/characterization is used to precisely capture EMI emission from device to system level or vice versa. The electromagnetic modeling methodology is used to pinpoint the root causes of unwanted EMI radiation on the module level.