Analysis on electromagnetic isolation issues among multi-chips in system in package

Electromagnetic isolation is a critical issue to the performance of radio frequency system in package (RF SIP). This paper proposes a novel structure to measure the electromagnetic (EM) isolation property and to test the shield efficiency of a metal cap. The 3-dimensional structure contains 5 antenna chips assembled is based on rigid and flexible substrates. EM interference and EM isolation relevance with different distances is revealed with ideal antenna simulation results in order to eliminate the parasitic effects. EM isolation properties in different horizontal distances are measured between different chips. Moreover, EM isolation properties in different vertical distances are measured using a structure like a pulley block. This paper also demonstrates EM isolation properties of a shield structure with a metal cap. The test results show the shield efficiency of a metal cap reaches more than 50dB. These results are constituent with the simulation results simulated by HFSS, a 3-dimensional electromagnetic field simulation software.