Interfacial morphology and shear deformation of flip chip solder joints

J. W. Jang, C. Y. Liu, P. G. Kim, King-Ning Tu, A. K. Mal, D. R. Frear

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

We examined the interfacial morphology and shear deformation of flip chip solder joints on an organic substrate (chip-on-board). The large differences in the coefficients of thermal expansion between the board and the chip resulted in bending of the 1-cm2 chip with a curvature of 57 ± 12 cm. The corner bump pads on the chip registered a relative misalignment of 10 μm with respect to those on the board, resulting in shear deformation of the solder joints. The mechanical properties of these solder joints were tested on samples made by sandwiching two Si chips with electroless Ni(P) as the under-bump metallization and 25 solder interconnects. Joints were sheared to failure. Fracture was found to occur along the solder/Ni3Sn4 interface. In addition, cracking and peeling damages of the SiO2 dielectric layer were observed in the layer around the solder balls, indicating that damage to the dielectric layer may have occurred prior to the fracture of the solder joints due to a large normal stress. The failure behavior of the solder joints is characterized by an approximate stress analysis.

Original languageEnglish
Pages (from-to)1679-1687
Number of pages9
JournalJournal of Materials Research
Volume15
Issue number8
DOIs
StatePublished - 1 Jan 2000

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