Comparison the reliability of small plated-through hole with different diameters under thermal stress

As the demand grows for multiple functionality and high density, the reliability of plated-through hole becomes a concern because of the difficulty in small window plating. The reliability of PTH was affected by many factors, for instance, drilled diameter and plated thickness. In this study, we mainly concentrate on the impact of PTH diameter on it. The diameter of PTHs engaged in this experiment ranges from 10 mil to 60 mil on the multilayer printed circuit boards with 96 mil thickness. All the test boards are subjected to thermal cycle test for 6000 cycles: from 0°C to 100°C with 10°C per minute ramp rate. The failure data was analyzed by using two-parameter Weibull distribution. The experimental results show that diameter of PTH affect the reliability much more at small PTH size. In order to understand the failure modes, cross section was applied to failed PTHs, which show the PTH failures under thermal stress in this study were due to cracks at the middle of PTH barrel.