Analysis of the EMI and SI effects on the flexible-PCBs for mobile application

The irregular shape of Flexible Printed Circuit Boards (FPCBs) causes the EMI problem or unstable signal integrity that is the important factor to system performance. The FPCBs that is used the general mobile phone is modeled and simulated in this paper And it is analyzed about the EMI and signal integrity effects as the changes of the FPCBs¿ position and shape. The structure of the FPCB consists of a base film, copper foil and coverlay. Material of the base film and a coverlay is polymide and conductor uses copper. The FPCBs are modeled as the FPCBs¿ shape inserted in folder and slide type mobile phone. In the folder type, the length of modeled FPCB is 40 mm, and the slide type FPCB is 100 mm. And according to the each case, the statuses of the FPCB when the slide is closed and open are modeled. According to the results of simulation, the strength of electric field is maximum 488.31 V/meter as the shape of FPCBs. And there are the differences in signal integrity. For the folder type, the bended FPCB model has about 2.1 dB loss at 800 MHz. And there is 0.5 dB loss as the number of bended shapes in the slide type FPCB model. The consequence is that the bended shape can cause the EMI and signal integrity problem.