Failure Analysis of Un-Wetting for the Surface Finish on the ENIG
Electroless nickel immersion gold (ENIG) is one of the most prevailing surface finishes for printed circuit board. It is widely adopted by manufacturers all over the world for its relative low price and compliance with the trend of high density packaging. However, its reliability is always of a concern. In this paper, the poor wetting performance of tin solder on the ENIG surface, which is one of its reliability issues was addressed. A series of modern facilities were utilized for finding the failure mechanism and chasing down the root cause. It was concluded that the inferior quality of immersion gold layer during plating, to be more specifically, the coarse and big grain size and the crystalline interface cracking were the main causes for the un-wetting failure. Last but not least, the improper choice of pure tin solder should also contribute to the final failure.
KeywordsENIG Un-wetting Grain size Failure analysis Oxidation
- 4.Chong, K.M., Tamil, S.S., Charan, G.: Discoloration related failure mechanism and its root cause in electroless nickel immersion gold (ENIG) pad metallurgical surface finish. In: Proceeding of 11th IPFA, pp. 229–233 (2004)Google Scholar
- 5.Lee, C.C., Chuang, H.Y., Chuang, C.K.: Oxidation behavior of ENIG and ENEPIG surface finish. In: Microsystems Packaging Assembly and Circuits Technology Conference, pp. 1–4 (2010)Google Scholar