Zincation characterization for electroless Ni/Au UBM of solder bumping technology

Tan, Qing; Beddingfield, C.; Mistry, A.; Mathew, Varughese

doi:10.1109/iemt.1998.731012

Cited by 4 publications

(2 citation statements)

References 1 publication

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“…Similar effects have been observed by Tan et al [20] who monitored the "coloration" of the bondpads under an optical microscope following a zincate treatment. They found five different levels of coloration and related these to the electrical resistance of the deposited electroless nickel bumps and strength of the interface.…”

Section: A Mechanism Of Zincate Depositionsupporting

confidence: 70%

“…The use of electroless nickel for the formation of the UBM in flip-chip assembly has prompted a number of studies of the zincate activation process applied to Al bondpads [15]- [20]. The etching and pretreatment stage of the bumping process has an important role to play in determining the overall properties and reliability of the final solder bumped flip chip.…”

Section: Introductionmentioning

confidence: 99%

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Electroless nickel bumping of aluminum bondpads. I. Surface pretreatment and activation

Hutt

Liu

Conway

et al. 2002

IEEE Trans. Comp. Packag. Technol.

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Electroless nickel bumping of aluminum (Al) bondpads followed by solder paste printing is seen as one of the lowest cost routes for the bumping of wafers prior to flip-chip assembly. However, the electroless nickel bumping of Al bondpads is not straightforward and a number of activation steps are necessary to enable the nickel deposit to form a strong, electrically conductive bond with the Al. For the electroless nickel coating of mechanical components made of aluminum, a zincate activation process has been used for many years, however extension of these techniques to semiconductor wafers requires careful control over these pretreatments to avoid damage to the very thin bondpads. This paper reports a number of experiments designed to characterize the activation of Al bondpads to electroless nickel plating, focusing on the effects of solution exposure time and bondpad composition. In addition, the results are discussed in the context of other studies presented in the literature to provide an understanding of the mechanism of the zincate activation process applied to Al bondpads.Index Terms-Electroless nickel, flip-chip, under bump metallization (UBM), wafer bumping, zincate.

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Section: A Mechanism Of Zincate Depositionsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Electroless nickel bumping of aluminum bondpads. I. Surface pretreatment and activation

Hutt

Liu

Conway

et al. 2002

IEEE Trans. Comp. Packag. Technol.

View full text Add to dashboard Cite

show abstract

Investigation of under bump metallization systems for flip-chip assemblies

Teo

Huang²,

Tung³

et al.

2000 Proceedings. 50th Electronic Components and Technology Conference (Cat. No.00CH37070)

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Direct bump-on-copper process for flip chip technologies

Ling

Sanchez

Moyer³

et al.

52nd Electronic Components and Technology Conference 2002. (Cat. No.02CH37345)

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Direct bump-on-copper technology provides a direct cost savings, equivalent bumping qualities, and better performance and reliability for products. The bump-on-copper FOC (flexon-cap) technology is modified and derived from the existing high volume, reliable, proven bump-on-aluminum FOC process. A copper compatible adhesion layer, namely, titanium, combined with a NiV barrier layer and a Cu wetting layer for solder are used to construct the tri-metal stack that defines a reliable under bump metallurgy (UBM) for flip chip solder bumps. A proprietary solder deposition technique using solder paste is then applied to form the solder interconnects. Bump quality tests such as bump height and bump shear strength demonstrates an equivalent structure to the existing Al/NiV/Cu based flip chip bump. Wafers constructed as described are tested at both wafer level and in an assembled level. All perform well in the preliminary reliability evaluation including temperature cycle (TC), thermal shock (TS), autoclave test (PCT), high temperature storage (HTS), high temperature operational life (HTOL), and high accelerated stress test (HAST).

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Zincation characterization for electroless Ni/Au UBM of solder bumping technology

Cited by 4 publications

References 1 publication

Electroless nickel bumping of aluminum bondpads. I. Surface pretreatment and activation

Electroless nickel bumping of aluminum bondpads. I. Surface pretreatment and activation

Investigation of under bump metallization systems for flip-chip assemblies

Direct bump-on-copper process for flip chip technologies

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