Abstract: To ensure a sufficiently high natural frequency of printed circuit board can effectively improve the anti-vibration capability of the printed circuit board for. Two typical sizes of printed circuit board(PCB) which are 3U and 6U are taken for example, their finite element models are established, and their natural frequencies are obtained by modal analysis. Optimal installation solutions are designed for 3U and 6U boards to solve their problems of low natural frequencies. The results show that the optimal installation solutions are easy to implement, they can significantly increase the natural frequencies for 3U and 6U boards and enhance the anti-vibration reliability, at the same time the installation solutions meet the needs of circuit design.

Key words:  modal analysis, PCB, finite element method, natural frequency, reliability