Analysis of time domain reflectometry for crack intermittency detection in circuit board

For the crack intermittency detection in circuit board, a detection method based on time domain reflectometry is proposed. And a time domain signal feature is extracted, the time domain signal feature is highly sensitive to the defect. Firstly, in order to analyze the change trend of time domain signal under intermittent disconnection. The influence of conductor crack on the physical parameters is analyzed. The physical parameters include AC/DC resistance, inductance and capacitance. And then the principle of signal reflection is described. The ringing phenomenon that caused by signal reflection is used for crack intermittency detection. Therefore the maximum, minimum and peak-peak values of time domain signal are used to detect intermittent disconnection. At last solder joint equivalent circuit is used to verify the effectiveness of the method. When the intermittent disconnection happened in circuit board, the time domain reflection phenomenon is observed clearly. The maximum, minimum and the peak-peak values of output voltage signal are changed greatly, simulation result shows that the high frequency signal is sensitive to intermittent disconnection, and the proposed method is effective.