Assessment of the reliability of the solder joints of the ultra-fine-pitch FCBGA

In this study, reliability assessment of the IMC layer of the ultra-fine-pitch FC-BGA(Flip-Chip Ball Grid Array) is conducted. The samples are prepared to reveal the differences in the adhesion forces of the IMC layer by dissimilarly establishing each plating thickness for surface finish(Ni/Pd/Au). The hardness and thickness of a P-rich Ni layer, which is known as the weakest section in ENPIG surface, are measured using the nano-indentation and TEM analysis. The degree of adhesion of the IMC layer under each experimental condition is evaluated and the metal plate shear test is performed for verification. The results showed significant correlations between the hardness and thickness of the IMC later and the high fraction defectives of the brittle fractures whose IMC layer had low hardness.