Research on the Effect of Mechanical Bending on Signal Transmission Characteristics of FPC

In order to study the problem of signal integrity caused by mechanical bending in flexible printed circuit board(FPC), the flexible substrate interconnection model under unbending and bending states was established by using simulation software HFSS15.0, then electromagnetic simulation analysis was conducted to obtain return loss S₁₁, insertion loss S₂₁ ,and they were compared and studied. At the same time, the bending radius of the flexible substrate was changed, and the influence of different bending radius on the signal transmission characteristics was studied. The results show that the non-curved substrate model reaches the optimum value near the 50GHz frequency in the frequency range of 1-70GHz, the return loss S₁₁ is greater than 10dB, the insertion loss S₂₁ is less than 1dB, and its transmission characteristics are better than the bending state model. At the same time, as the bending radius is larger, the signal quality of the transmission line is better and the signal is more suitable for transmission.