Metallurgical reactions of Sn-3.5Ag solder with various thicknesses of electroplated Ni/Cu under bump metallization

Chang Pin Huang, Chih Chen*, C. Y. Liu, S. S. Lin, K. H. Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Nickel has been widely used as an under-bump metallization (UBM) material in the microelectronics industry. The solid-state reaction between the eutectic SnAg solder bumps and three thicknesses of Ni/Cu UBM was investigated, with 5 μm-Cu/3 μm-Ni, 3 μm-Cu/2 μm-Ni, and 0 μm-Cu/1 μm-Ni. It was found that the shear strength of the solder bumps decreased after the solid-state aging at 150 °C for 200 h, and it did not change much after it was prolonged for 500 and 1000 h. Aging of the Ag 3 Sn intermetallic compound (IMC) and grain growth of the solder are responsible for the decrease in the shear strength. Furthermore, the shear test results indicated that the fracture mode switched from ductile to brittle for the solder bumps with 1 μm Ni after aging longer than 200 h, causing the strength of the solder to decrease abruptly. This is attributed to the consumption of the peripheral Ni layer after the solid-state aging for 1000 h. The Ni consumption rate was measured to be 0.02 μm/h 1/2 at 150 °C.

Original languageEnglish
Pages (from-to)2772-2779
Number of pages8
JournalJournal of Materials Research
Volume20
Issue number10
DOIs
StatePublished - 1 Oct 2005

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