TDR measurement of a solder under temperature cycle test

With the decrease in the overall size and the rapid increase in the working frequencies of printed circuit boards, the reliability of solder joints, especially the high frequency signal transmission reliability has become the key factor in system reliability. In this paper, changes in RF impedance of solder joints in a temperature cycling environment was studied using time-domain reflectometry measurements. It was found that with the increase in the temperature cycle, the intermetallic compound layer gradually thickened, and even if no macro damage was found, the RF impedance increased. The transmission reliability of the high frequency signal was degraded.