Electroless deposition of bumps for TAB technology

Simon, J.; Zakel, E.; Reichl, H.

doi:10.1109/ectc.1990.122223

Cited by 36 publications

(13 citation statements)

References 1 publication

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“…However, electroless plating is a simpler and more elegant process, because it depends solely on the autocatalytic action of the plating bath, while electrolytic deposition is based on cathodic discharge of metal ions. Electroless plating progresses almost linearly with time, resulting in a very uniform deposition, which is crucial for achieving uniform bump height over all the elements of a bond pad array [7], [8].…”

Section: Electroless Remetallization-process and Discussionmentioning

confidence: 99%

Electroless remetallization of aluminum bond pads on CMOS driver chip for flip-chip attachment to vertical cavity surface emitting lasers (VCSEL's)

Datta

Merritt²,

Dagenais

1999

IEEE Trans. Comp. Packag. Technol.

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A method for remetallizing the bond pads of electronic chips, which are initially metallized with aluminum or aluminum alloy is presented. Application of electroless plating process for the remetallization of aluminum to a solderable gold surface can reduce the cost and complication of the widely accepted flip-chip interconnection technology. We have developed a step by step nickel/gold wafer bumping technique (remetallized bump height is 5.0 m) for the appropriate solder (15.0 m of In : Pb). Variation of roughness of the remetallized surface has been studied carefully. We have completed prototype research studies on test devices and successfully packaged the flip-chip bonded hybrid pair of a CMOS driver chip and a dummy structure of vertical cavity surface emitting laser (VCSEL) array. Cross section of the flip-chip solder joint is studied. Also, adhesion strength of the metal deposit is investigated. Index Terms-Ball shear test, electroless plating, flip-chip bonding, indium-lead solder, remetallization of aluminum, VCSEL packaging, wire-bonding.

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Section: Electroless Remetallization-process and Discussionmentioning

confidence: 99%

Electroless remetallization of aluminum bond pads on CMOS driver chip for flip-chip attachment to vertical cavity surface emitting lasers (VCSEL's)

Datta

Merritt²,

Dagenais

1999

IEEE Trans. Comp. Packag. Technol.

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“…Typical examples of applications include metal finishing of printed-circuit-boards, 1 filling of via-holes in multilevel interconnection, 2,3 fabrication of multi-chip modules 4 and the formation of solder bumps in tape-automated-bonding technology. 5 In recent years, EN has caught particular attention in the low-cost flip chip bumping technology, which combines electroless nickel and immersion gold with solder printing techniques. 6,7 Other reasons for the popularity of EN in wafer bumping include the cost saving from maskless processing and batch processing, 8 bump uniformity, 5 superior diffusion barrier performance, 9 -11 slow growth rate of Ni-Sn intermetallic compounds 12 and satisfactory solderability.…”

Section: Introductionmentioning

confidence: 99%

“…5 In recent years, EN has caught particular attention in the low-cost flip chip bumping technology, which combines electroless nickel and immersion gold with solder printing techniques. 6,7 Other reasons for the popularity of EN in wafer bumping include the cost saving from maskless processing and batch processing, 8 bump uniformity, 5 superior diffusion barrier performance, 9 -11 slow growth rate of Ni-Sn intermetallic compounds 12 and satisfactory solderability. 13 Among all these factors, solderability is perhaps the most critical.…”

Section: Introductionmentioning

confidence: 99%

Surface properties and solderability behaviour of nickel–phosphorus and nickel–boron deposited by electroless plating

Chow

Lau

Karim

2001

Surface & Interface Analysis

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X-ray photoelectron spectroscopy (XPS), scanning Auger microscopy (SAM), atomic force microscopy (AFM) and wetting force measurements have been applied to various nickel deposits prepared by standard electroless plating for probing the origins of solderability behaviour of 'electroless nickel'. By controlling the plating chemicals and plating conditions, three kinds of electroless nickel deposits have been prepared, namely electroless nickel-high phosphorus (EN-HP), electroless nickel-low phosphorus (EN-LP) and electroless nickel-boron (EN-B). Wetting balance measurements confirmed the solderability strength decreased in the order of EN − B > EN − LP > EN − HP. Unexpectedly, among the three EN deposits, EN-B was found by XPS to have the thickest surface oxide, which opposes the traditional correlation of good solderability with thin surface oxide. On the other hand, SAM and AFM studies showed that the average nodule size increased in the order of EN − B < EN − LP < EN − HP. Accordingly, there appeared to be a correlation of small nodule size with good solderability. Solderability of 'electroless nickel' thus depended more on surface morphology than on surface oxidation. Nevertheless, further studies of the wetting kinetics of the EN deposits revealed that among the three EN deposits EN-HP had the oxide structure that was most difficult to penetrate and thus the slowest to 'wet'. The structure of the surface oxide therefore was found to affect the wetting kinetics of 'electroless nickel'.

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“…Electroless refers to the autocalytic or chemical reduction of metal ions plated onto a base substrate from an aqueous solution [1] . The depositions are very uniform because no external current is required hence the deposition rate is not influenced by current distribution in the plating cell.…”

Section: Introductionmentioning

confidence: 99%

The Characterization of Al Bond Pad Surface Treatment in Electroless Nickel Immersion Gold (ENIG) Deposition

Arshad¹,

Jalar²,

Ahmad³

et al. 2007

American J. of Applied Sciences

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Abstract:This study reports a number of experiments that were designed to characterize aluminum bond pad surfaces prior to electroless nickel immersion gold (ENIG). In the ENIG process, aluminum bond pads need special treatment to achieve successful nickel deposition and provide reliable interconnection of under bump metallurgy in advanced packaging. During this treatment process, the aluminum pad was cleaned, activated and then coated with a layer of zinc. Systematic study was carried out to determine the best parameters, through multiple and various exposure times of the zincation process and zincation solution concentration effect on the Ni/Au surface roughness and aluminum dissolution rate on the bond pad during multiple zincation process. The ball shear strength was evaluated between eutectic 37Pb/63Sn solder ball and under bump metallurgy (UBM) interfaces across multiple zincation process. Scanning Electron Microscope (SEM), Energy Dispersive X-Ray (EDX), Atomic Force Microscopy (AFM), Focused Ion Beam (FIB) and ball shear tester were used as analytical tools. The results suggest that the multiple zincation process consistently produces a smoother surface of ENIG UBM and consequently provides a better shear strength.

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Electroless deposition of bumps for TAB technology

Cited by 36 publications

References 1 publication

Electroless remetallization of aluminum bond pads on CMOS driver chip for flip-chip attachment to vertical cavity surface emitting lasers (VCSEL's)

Electroless remetallization of aluminum bond pads on CMOS driver chip for flip-chip attachment to vertical cavity surface emitting lasers (VCSEL's)

Surface properties and solderability behaviour of nickel–phosphorus and nickel–boron deposited by electroless plating

The Characterization of Al Bond Pad Surface Treatment in Electroless Nickel Immersion Gold (ENIG) Deposition

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