Detailed investigation of ultrasonic Al–Cu wire-bonds: I. Intermetallic formation in the as-bonded state

Drozdov, M. A.; Gür, Gökçe; Atzmon, Z.; Kaplan, Wayne D.

doi:10.1007/s10853-008-2954-x

Cited by 49 publications

(25 citation statements)

References 22 publications

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“…This finding is different from the Selective Area Diffraction phase identification in the study of Xu [2] and Drozdov [15] that shows Al 2 Cu is the only phase formed in as-bonded Cu wireeAl bond pad metallization interface. This finding could be explained by higher frequency generated by ultrasonic transducer in the modern wire bonders in their studies.…”

Section: Resultscontrasting

confidence: 87%

“…Besides, this oxide does not hinder the interdiffusion of Cu and Al atoms to form IMC. Similar detection of Oxygen element in the void at the interface of Cu/Al of as-bonded sample with Forming Gas supply is found in the work of Drozdov [15] that evident the minor oxide exists at the bonding interface. EDX signal intensity profile of Cu and Al that vary continuously across the interface shows a much slower signal intensity change (and thus composition change) at certain region indicating the existence of an approximate stoichiometric intermetallic phase.…”

Section: Resultssupporting

confidence: 82%

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Oxidation study on as-bonded intermetallic of copper wire–aluminum bond pad metallization for electronic microchip

Anand

Yau

Huat³

2012

Materials Chemistry and Physics

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Section: Resultscontrasting

confidence: 87%

Section: Resultssupporting

confidence: 82%

Oxidation study on as-bonded intermetallic of copper wire–aluminum bond pad metallization for electronic microchip

Anand

Yau

Huat³

2012

Materials Chemistry and Physics

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“…of Al-Cu intermetallics could be found, whereas Drozdov et al identified Al 2 Cu nuclei in the very initial state [10]. Therefore, it may be concluded that the as-bonded microstructure highly depends on the bonding parameters as well as on the surface condition of the parts to be bonded.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 97%

Role of intermetallics on the mechanical fatigue behavior of Cu–Al ball bond interfaces

Lassnig

Pelzer

Gammer

et al. 2015

Journal of Alloys and Compounds

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The mechanical fatigue behavior of Cu-Al interfaces occurring in thermosonic ball bonds -typically used in microelectronic packages for automotive applications -is investigated by means of a specially designed fatigue test technique. Fully reversed cyclic shear stresses are induced at the bond interface, leading to subsequent fatigue lift off failure and revealing the weakest site of the bond. A special focus is set on the role of interfacial intermetallic compounds (IMC) on the fatigue performance of such interfaces. Therefore fatigue life curves were obtained for three representative microstructural states: The asbonded state is compared to two annealed states at 200 ℃ for 200 h and at 200 ℃ for 2000 h respectively. In the moderately annealed state two IMC layers (Al 2 Cu, Al 4 Cu 9 ) could be identified, whereas in the highly aged state the original pad metallization was almost entirely consumed and AlCu is formed as a third IMC. Finally, the crack path is traced back as a function of interfacial microstructure by means of electron microscopy techniques.Whereas conventional static shear tests reveal no significant decrease of the bond shear force with increased IMC formation the fatigue tests prove a clear degradation in the cyclic mechanical performance. It can be concluded that during cycling the crack deflects easily into the formed intermetallics, leading to early failure of the ball bonds due to their brittle nature.

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“…It is necessary to use transmission electron microscopy [20]. Without the ability to examine the welded area, more care needs to be taken with process optimization to ensure a robust bonding process.…”

Section: The Ball Bonding Processmentioning

confidence: 99%

What is the future of bonding wire? Will copper entirely replace gold?

Breach¹

2010

Gold Bull

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Thermosonic ball bonding is a major interconnect process in microelectronics packaging and is positioned to remain one of the key process technologies available to package designers in the near future. However, the main wire material used in fine pitch (FP) and ultra-fine pitch (UFP) ball bonding is gold and with significant increases in gold price, gold ball bonding has become a more costly process that has a considerable economic effect on the assembly of packages used in consumer electronics. An alternative wire material to gold is copper, which is much cheaper and has several technical benefits including better electrical conductivity and has been widely used in discrete and power devices with wire diameters typically larger than 30μm in diameter for many years. However, copper wire behaves quite differently than gold due to its different physical properties, some of which are beneficial and others detrimental to bonding performance. In this article, we briefly review some of the advantages and difficulties with using copper wire advanced packaging and explain why copper cannot replace gold in many applications and why gold offers significant benefits.

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Detailed investigation of ultrasonic Al–Cu wire-bonds: I. Intermetallic formation in the as-bonded state

Cited by 49 publications

References 22 publications

Oxidation study on as-bonded intermetallic of copper wire–aluminum bond pad metallization for electronic microchip

Oxidation study on as-bonded intermetallic of copper wire–aluminum bond pad metallization for electronic microchip

Role of intermetallics on the mechanical fatigue behavior of Cu–Al ball bond interfaces

What is the future of bonding wire? Will copper entirely replace gold?

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