Effect of ENEPIG metallization for solid-state gold-gold diffusion bonds

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

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Original languageEnglish
Pages (from-to)339-348
Journal / PublicationMicroelectronics Reliability
Online published29 Sep 2017
Publication statusPublished - Nov 2017


Gold-gold (Au–Au) diffusion bonding behavior of different tri-layer thicknesses of Electroless Ni/Electroless Pd/Immersion Au (ENEPIG) plating on a high-density system on a flex (SOF) package was examined. Plating thickness has a significant effect on surface roughness and void formation at the Au–Au bonding interface, which exhibits degraded bond strength with an affected failure mode. It is seen that relatively smooth surface roughness (Ra < 100 nm) of thicker Ni(P) plating samples facilitates the shrinkage of voids and significantly increases bonding strength. Higher surface roughness in the low Ni(P) sample has a poor surface profile, which results in large lenticular shape voids and requires more energy to shrink by diffusion and a creep process. Enhancing bonding parameters constitutes an essential feature to compensate the physical and mechanical properties of ENEPIG plating. Based on this study, the authors recommend a suitable ENEPIG plating thickness for a high quality metallurgical bond, which passes different reliability tests.

Research Area(s)

  • Au–Au diffusion bonding, Effect of ENEPIG plating thickness, Effect of micro surface roughness, Medical devices, System on flex, Thermo compression bonding