Copper versus palladium coated copper wire process and reliability differences

Lee, Chu-Chung Stephen; Tran, Thomas; Boyne, D.M.; Higgins, Laura M.; Mawer, Andrew

doi:10.1109/ectc.2014.6897499

Cited by 22 publications

(5 citation statements)

References 5 publications

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“…This study has three strengths ( Figure 14 ). First, a quaternary alloy APAP wire was used to replace the common coated wire to reduce the galvanic corrosion caused by the multilayered metal when the wire is bonded to the substrate [ 28 ]. Furthermore, the diameter of the quaternary alloy APAP in this study was 15 μm, which is thinner than the silver wire with a diameter of 18–20 μm currently available in the market, reducing the use of precious metals and increasing the packaging density.…”

Section: Resultsmentioning

confidence: 99%

Metallographic Mechanism of Embrittlement of 15 μm Ultrafine Quaternary Silver Alloy Bonding Wire in Chloride Ions Environment

2023

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Chloride ions contained in the sealing compound currently used in the electronic packaging industry not only interact with intermetallic compounds but also have a serious impact on silver alloy wires. A 15 μm ultrafine quaternary silver-palladium-gold-platinum alloy wire was used in this study. The wire and its bonding were immersed in a 60 °C saturated sodium chloride solution (chlorination experiment), and the strength and elongation before and after chlorination were measured. Finally, the fracture surface and cross-section characteristics were observed using a scanning electron microscope and focused ion microscope. The results revealed that chloride ions invade the wire along the grain boundary, and chlorides have been generated inside the cracks to weaken the strength and elongation of the wire. In addition, chloride ions invade the interface of the wire bonding to erode the aluminum substrate after immersing it for enough long time, causing galvanic corrosion, which in turn causes the bonding joint to separate from the aluminum substrate.

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Section: Resultsmentioning

confidence: 99%

Metallographic Mechanism of Embrittlement of 15 μm Ultrafine Quaternary Silver Alloy Bonding Wire in Chloride Ions Environment

2023

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“…of IMCs in PdCu wire bonding [43,[63][64][65][66]. Xu et al [19] compared the IMCs thickness between the bonding of bare Cu wire and PdCu wire at the aging temperature of 175 °C.…”

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

confidence: 99%

“…According to the binary phase diagram of the Cu-Al system, it can be observed that five types of IMCs can be formed at 150-300 °C, namely Cu9Al4, Cu3Al2, Cu4Al3, CuAl, and Scholars have found through research that the formation of Kirkendall voids is also related to the growth of IMCs, as the volume of IMCs decreases due to phase transition, resulting in the formation of Kirkendall voids [77,78]. Lee et al [66] stored the bonded samples of PdCu wires with a diameter of 20 µm at high temperature for 14,098 h and found that cracks appeared at the periphery of the bonding interface when the Cu Al IMCs phase transformed from Cu rich to Al rich. They believed that the cracks were caused by volume changes during the IMCs phase transition.…”

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

confidence: 99%

“…Early studies have shown that the Cu-Al IMCs of bare Cu wire is hard and brittle [ 56 , 57 , 58 ], but in the Cu-Al IMCs of PdCu wire, because the electronegativity difference between Pd and Cu is very small (Pd is 2.2, Cu is 1.9) [ 59 , 60 ], it is easy to form a solid solution with a face-centered cubic structure, so the Cu-Al IMCs of PdCu wire has better ductility and a slower growth rate [ 61 ]. It has been reported that Cu-Al IMCs in PdCu wire bonding is thinner than that in bare Cu wire bonding [ 62 ], because Pd can slow down the growth rate of IMCs in PdCu wire bonding [ 43 , 63 , 64 , 65 , 66 ]. Xu et al [ 19 ] compared the IMCs thickness between the bonding of bare Cu wire and PdCu wire at the aging temperature of 175 °C.…”

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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“…Xu et al studied the behavior of PCC wire and its impact on IMC growth in those wire bonding devices and reported the IMC corrosion problem [9]. Meanwhile, Lee et al reported mechanical reliability studies comparing PCC and Cu wire, where both showed the same chloride induced corrosion resistance if Cu/Al IMC formation was properly formed [10]. Whereas Lim et al and Wu et al studied the corrosion performance of Cu/Al IMC with the effect of Pd addition, showing slightly improved corrosion resistance in Cu and Cu/Al samples [11,12].…”

Section: Introductionmentioning

confidence: 99%

Exploration of Interfacial Materials Chemistry Control to Improve Cu Wire Bonding Reliability

Chyan,

Durai,

Kumaravel

et al. 2024

IMAPSource Proceedings

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Copper wire bonding, with its advantages of higher electrical conductivity and better mechanical strength, has replaced gold wire bonding as a proven cost-effective electrical interconnection solution for IC packaging for the past 15 years. Early development of Cu wire bonding required overcoming of several technical challenges including bond pad damage caused by copper’s hardness and brittleness relative to gold. A more chemistry related challenge of using Cu as bonding wire is its well-known reactivity with oxygen. Inert atmospheric envelope of forming gas surrounding bonding capillary was developed to prevent oxidation of Cu wire during electronic flame off to enable a strong bonding. Another more elusive materials-chemistry related reliability challenge, with a typical low ppm occurrence, has been the chloride-induced corrosion defects between the Cu wire and Al bond pad. The opportunistic low-level chloride contaminations can originate from various points of packaging manufacturing process flow and often render it un-trackable. In this talk, we present recent efforts to systematically control interfacial materials chemistry across Cu bonding wire, Cu/Al bimetallic contacts and CuxAly intermetallic compounds with the aim to eliminate corrosion defects and improve the overall bonding reliability. The current prevailing manufacturing solution is to utilize Pd-coated Cu bonding wire that can only partially mitigate the CuxAly intermetallic corrosion vulnerability. We utilized a real-time corrosion screening metrology to explore the underlying interfacial materials chemistry drives vigorous corrosion between Cu wire and Al bond pad when exposed to trace level of chloride contaminant. Combining with SEM, sensitive infrared spectroscopy and electrochemical characterization, our data show strategic surface modification on both Cu bonding wire and exposed CuxAly intermetallic can have a significant impact on reducing corrosion defect rates. The obtained mechanistic insights provide several new strategies enabled by a novel Cu-selective passivation coating technology to effectively mitigate Cu wire bonding corrosion defects. Implications on further improving overall Cu wire bonding reliability will be present based on these new approaches that have low-cost and packaging friendly advantages.

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Copper versus palladium coated copper wire process and reliability differences

Cited by 22 publications

References 5 publications

Metallographic Mechanism of Embrittlement of 15 μm Ultrafine Quaternary Silver Alloy Bonding Wire in Chloride Ions Environment

Metallographic Mechanism of Embrittlement of 15 μm Ultrafine Quaternary Silver Alloy Bonding Wire in Chloride Ions Environment

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

Exploration of Interfacial Materials Chemistry Control to Improve Cu Wire Bonding Reliability

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