Ultra-fine pitch palladium-coated copper wire bonding: Effect of bonding parameters

Lim, Adeline B.Y.; Chang, Andrew; Yauw, Oranna; Chylak, Bob; Gan, Chee Lip; Chen, Zhong

doi:10.1016/j.microrel.2014.05.005

Cited by 18 publications

(11 citation statements)

References 7 publications

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“…According to the Cu-Pd phase diagram [44], FCC continuous solid solution (Cu, Pd) exists above 598 • C. Because the melting point of Cu is 1083 • C, when the ball is burned, the copper bonding wire melts, and Pd is likely to dissolve in the Cu matrix to form a solid solution. Lim et al [40] found that the heat energy generated by EFO sparks is mostly used to provide the melting of Cu wire, Pd will not completely melt, Pd and Cu will form a solid solution, but will not form a uniform solid solution. Yeung et al [45] found that in the actual melting process of PdCu wire, the heating duration is too short, and Pd cannot be completely dissolved into the Cu matrix before FAB cooling.…”

Section: The Distribution Of Pd In Fab and Bonding Interfacementioning

confidence: 99%

“…The study found that different EFO discharge current settings lead to full or partial coverage of Pd on FAB and will also directly affect the distribution of Pd at the bonding interface. Lim et al [ 39 , 40 ] used 0.6 mil PdCu wires to conduct experiments under low, medium, and high EFO discharge current settings. Then, a FEI dual beam focused ion beam (FIB) system was used to analyze the cross-section of FAB samples.…”

Section: The Distribution Of Pd In Fab and Bonding Interfacementioning

confidence: 99%

“…Lim et al [ 64 ] found Kirkendall voids where there was Pd at the bonding interface of the PdCu wire, and no Kirkendall voids were found where there was no Pd. Lim et al [ 40 ] studied the relationship between the formation of Kirkendall voids and the presence of Pd by setting low, medium, and high EFO discharge currents for bonding experiments, and then storing them in air at 175 °C for 168 h. As shown in Figure 22 , for low EFO discharge current, no visible Pd-rich layer is found at the bonding interface, and a visible Pd-rich layer is found at the bonding interface with optimized low EFO discharge current; for the medium EFO discharge current, the presence of Pd was found at the bonding interface; for high EFO discharge current, some Pd injection was observed in the bonding ball. The high-temperature storage bonding interface of the test sample under the optimized low EFO discharge current setting is shown in Figure 23 .…”

Section: The Effect Of Pd On Intermetallic Compounds (Imcs) and Relia...mentioning

confidence: 99%

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Research Progress of Palladium-Plated Copper Bonding Wire in Microelectronic Packaging

Zhang,

Guo,

Cao

et al. 2023

Micromachines

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Wire-bonding technology is the most commonly used chip interconnection technology in microelectronic packaging. Metal bonding wire is the key material for wire bonding and plays an important role in the reliability of electronic devices. In recent years, palladium-plated copper (PdCu) bonding wire has been widely used because of its low cost, good electrical and thermal conductivity, the fact that it is not easy to oxidize, and its high reliability. Therefore, it is necessary to review its research progress. In this paper, the preparation and application of palladium-plated copper bonding wire are reviewed. Firstly, the preparation methods of electroplating, electroless plating, and direct plating are introduced. Secondly, the factors affecting the distribution of Pd in free air balls and bonding interfaces, the effect of Pd on the formation and growth of intermetallic compounds in PdCu wire, stitch bond, and reliability of PdCu wire are summarized and analyzed in the application process. Finally, its development prospect is prospected. Hopefully, this review can help readers to have a comprehensive understanding of the preparation and application of palladium-plated copper bonding wires, and can accelerate the promotion of its application in more fields in the future.

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Section: The Distribution Of Pd In Fab and Bonding Interfacementioning

confidence: 99%

Section: The Distribution Of Pd In Fab and Bonding Interfacementioning

confidence: 99%

Section: The Effect Of Pd On Intermetallic Compounds (Imcs) and Relia...mentioning

confidence: 99%

See 1 more Smart Citation

Research Progress of Palladium-Plated Copper Bonding Wire in Microelectronic Packaging

Zhang,

Guo,

Cao

et al. 2023

Micromachines

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“…Next is the setup of the important parameters of the wire bonder, which are substrate temperature, bonding force, ultrasonic power, and bonding time. These parameters may vary depending on the materials being bonded and the desired bond strength [4]. After that is the wire bonding process, where the wire bonding machine uses a combination of heat, pressure, and ultrasonic energy to create a bond between the thin film and the component.…”

Section: Introductionmentioning

confidence: 99%

Study of bonding parameters with Al and Au wires on Pd and Ag coatings

Tomov,

Kolev,

Dobrikov

et al. 2024

J. Phys.: Conf. Ser.

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The process of electrical connection with gold and aluminium wires to palladium and silver electrodes is studied. Parameters of the wire bonding, such as bond force, ultrasonic power, bond time and temperature of the layers, controlled by heating the substrate are varied to explore the reliability of the bonds in terms of mechanical strength, electrical conductivity and interdiffusion of particles between the electrode and functional material at different bonding conditions. The importance of this study is due to the need of electrical connectivity at the stage of wiring and packaging of gas sensors with a novel organic nanomaterial (carbyne), requiring different types of electrodes – Ohmic or Schottky - according to the measurement principle and sensor architecture. Pd and Ag are identified as the most suitable for Ohmic and Schottky contacts, respectively, because of their favourable energy level alignment at the organic/metal interface. The chosen method for bonds testing is measurement of the pull force causing bond failure. The results show that Pd coating was bondable by Au wire, and Ag coating by Al wire, as well as Au on Pd bonds have 4 times higher strength. It is found that the bonding procedure doesn’t affect negatively on the Au/Pd/carbyne interface in terms of diffusion and redistribution of metal particles, but Al/Ag/carbyne is characterized by poor adhesion and the bonds are peeled-off. The results give new knowledge for the fabrication of advanced gas sensors and for the interaction of the carbyne with different metals, which will serve as a base for further optimization of the manufacturing technology toward their commercialization.

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“…It was reported that the IMC phases identified in the Cu/Al bond interface are typically CuAl 2 , CuAl and Cu 9 Al 4 ; the latter two IMCs are mostly found after thermal treatment [10]. In a recent study on ultra-fine (15 μm) Pd-Cu wire bonds on Al bond pads [12], Pd was detected on the free air ball surface after electronic flame off (EFO) firing, which will affect the composition at the bond interface and the Cu-Al IMCs phase formation. So far, no systematic study has been carried out to investigate the corrosion resistance of individual Cu-Al IMCs, as well as the effect of Pd on the corrosion resistance of these metals and IMCs in a chloride medium.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the corrosion performance of Cu-Al intermetallic compounds and the effect of Pd addition

Lim

Neo

Yauw

et al. 2015

2015 IEEE 17th Electronics Packaging and Technology Conference (EPTC)

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Copper wire has become a mainstream bonding material in fine-pitch applications due to the rising cost of gold wire. In recent years, palladium-coated copper (Pd-Cu) wire is being increasingly used to overcome some constraints posed by pure Cu wire. During wire bonding with aluminum bond pads, different intermetallic compound (IMC) phases that have been identified at the bond interface are typically CuAl 2 , CuAl and Cu 9 Al 4 . Copper wire bonds were reported to fail humidity reliability tests and Cu 9 Al 4 was observed to be the corroded IMC layer. However, the corrosion susceptibility of the individual IMCs has not been investigated. There has also been conflicting results on the effect of palladium on the reliability of copper wire bonds reported in literature. This paper compares the corrosion performance of the three types of Cu-Al IMCs in a chloride medium by employing electrochemical potentiodynamic polarization. A comparison was made with pure Cu and Al. The effect of Pd on the IMC corrosion performance was also studied. Among the three CuAl IMCs, Cu 9 Al 4 was observed to have the largest corrosion rate followed by CuAl 2 and CuAl. For the metals, Cu was observed to have the lowest corrosion rate and Al is the most easily corroded. The addition of a few percent of Pd slightly improves the corrosion resistance of the metals and IMCs.

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Ultra-fine pitch palladium-coated copper wire bonding: Effect of bonding parameters

Cited by 18 publications

References 7 publications

Research Progress of Palladium-Plated Copper Bonding Wire in Microelectronic Packaging

Research Progress of Palladium-Plated Copper Bonding Wire in Microelectronic Packaging

Study of bonding parameters with Al and Au wires on Pd and Ag coatings

Evaluation of the corrosion performance of Cu-Al intermetallic compounds and the effect of Pd addition

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