Effects of Shielding Materials on EMI Performance for 5G Wi-Fi Applications

Electronic communication devices used in many fields such as the internet, military, electronic industry, medical care, and electronic payment are growing rapidly. However, these demands lead to a new type ofpollution called noise or radio frequency interference (RFI) or electromagnetic interference (EMI), which may interfere with equipment performance and cause equipment shutdown. As a result, there is a great need for electromagnetic waves shielding and other components in the module would not be disturbed by outer electromagnetic waves. In this study, the influence factors of EMI shielding include forming process, coating thickness and material. Silver and copper are the metals adopted in EMI shielding due to their excellent properties of electrical conductivity and magnetic permeability. We focus on the effects of coating thickness and different processes including sputter, screen printing and spray. 2.4 GHz/5 GHz Wi-$\Gamma$i module is utilized for EMI shielding test. The results ofEMI block are measured by Keysight N9010B equipment to check electromagnetic waves shielding capability by dBm value at 4. 8GHz (2nd harmonic), 7.2 GHz (3rd harmonic) and 6.43 GHz (noise). Besides measurement by using functional products, radiation simulation is used to simulate antenna efficiency under designed coating thickness ofEMI shielding layer. The results of simulation and experiments show that coating thickness is the key factor to affect EMI shielding effectiveness. Moreover, processes of screen printing and spray are applicable and would be cost-effective alternates compared to sputtering.