BioVale

ABSTRACT The reliability of high-density interconnect (HDI) printed circuit boards (PCBs) is strongly influenced by the integrity of microvias, which serve as critical vertical interconnects between layers. Although microvias enable compact designs and improved electrical performance, they are prone to failures such as cracking, void formation, and delamination, particularly under thermal and mechanical stress. Traditional inspection methods provide only limited insight into these complex failure mechanisms. This paper highlights the application of advanced characterization techniques — including optical microscopy, X-ray imaging, electrical testing, scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD), focused ion beam (FIB) cross-sectioning, transmission electron microscopy (TEM) with electron energy-loss spectroscopy (EELS), and nano beam diffraction (NBD). Together, these methods provide complementary structural, chemical, and crystallographic information across multiple scales. Case studies demonstrate how these tools reveal defect origins, such as contamination and interfacial weakness, and link microstructural features to failure mechanisms. The integration of these techniques not only deepens scientific understanding but also provides manufacturers with actionable feedback to refine drilling, cleaning, and plating processes, thereby improving the reliability of next-generation HDI PCBs.