Effect of contact resistance on conformai shield package for mobile DRAM

In the event of failure to control interference from parts to antennas, the mobile systems cannot perform properly. Also, the EMI certification tests cannot be passed. An effective way to reduce the EMI radiation from components is using a metallic shield can, but it does not meet the demands of miniaturization and flexibility trends in recent mobile devices. A conformal shield package that can compensate for the weakness of shield can is being used more and more. In this paper, the shield effect by applying the conformal shield on package was investigated. For accurate measurement, EMI jig was designed and conformal shield packages were prepared using a silver spray method. Using a near field scan method, the effects of conformal shield packages were investigated. After reducing the contact resistance, the Magnetic field radiation of LP4x was improved by more than 10 dB in all frequency bands. It is founded that the contact resistance management is very critical to ensure uniform EMI characteristics of the conformal shield packages.