The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hee Seon Bang - One of the best experts on this subject based on the ideXlab platform.
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comparison of interface evolution of ultrasonic aluminum and Gold Wire wedge bonds during thermal aging
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Chunqing Wang, Han Sur Bang, Hee Seon BangAbstract:Ultrasonic Gold and aluminum Wire wedge bonding are widely used for electrical and signal interconnections of the integrated circuit chip packages. In this paper, based on the metallurgical theories and thermal aging test methods, the long-term thermal reliabilities of Gold and aluminum Wire wedge bonding on aluminum and Au/Ni/Cu pads, were investigated, respectively. At 200 ◦ C, the Au/Al bond interfaces evolved little when the storage time was less than 48 h; with the aging time increasing, the interfacial intermetallic compounds (IMC) grew up from the pad (vertical growth); the primary compounds were Au5Al2 near the bond toe and heel, and Au2Al at the periphery. Then, the thickness of IMC was unchanged, and extended horizontally (lateral growth), Au5Al2 transformed into more stable Au2Al phase, furthermore, cracks ran through the interface of the Gold and IMC because of severe Kirkendall voids. However, Al/Au bond was more stable, and the IMC grew slowly. The purple plague AuAl2 resulted in interfacial cracks. Moreover, the bond Wire was filled with cavities.
Charles J Vath - One of the best experts on this subject based on the ideXlab platform.
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bonding Wire options and their impact on product reliability
International Conference on Electronic Packaging Technology, 2011Co-Authors: Charles J Vath, Richard HollidayAbstract:With the current Gold price, the semiconductor industry finds itself caught in a dilemma. The industry has traditionally maintained an average 15% cost down per year per function over the range of products it offers [1]. Part of this reduction comes from packaging where manufacturing efficiencies such as cycle time reduction, supply chain management, and yield improvement allow for continued reductions in the cost per I/O. As the leaded package families are expected to increase in volume, while die sizes shrink over the same period, continued cost reduction will be difficult to achieve based on current practices and raw material prices. The need to remain competitive has compelled integrated device manufacturers and subcontractors to look at alternative material types, most notably copper Wire. A recent survey of the industry has revealed that there remain very widespread concerns on migrating away from the use of Gold [2]. One needs to carefully study the history of Gold and copper in the manufacturing of semiconductor devices and their roles in the various interconnect methods used, both at the die level as well as the package level. Gold has been the preferred final plating layer in PCBAs for more than 65 years. Gold Wire has been used for the vast majority of Wire bonded interconnects for more than 50 years. Yet, we are still discovering new failure mechanism brought about, in part, by the introduction of new materials both in the wafer fabrication processes and in the package assembly area. Man has used copper for more than 10,000 years. As wiring, copper has been the preferred base material. It has also been the dominant material used in lead frames and PCBAs. For interconnections on the chip and from the chip to the lead frame, it is still in its very early stages. At the die level copper compromises dielectric properties resulting in circuit inoperability [3]. In die metallization, high concentrations of copper in the aluminum films result in localized corrosion during storage and at the wafer saw operation [4]. At the die metallization / ball bond interface, a galvanic cell is established in the presence of moisture and halides that leads to rapid degradation of the bond's electrical properties and mechanical strength [5]. In addition, research over the last two years indicates that there are reliability related issues with the copper/aluminum bond when exposed to tests that utilize high moisture levels [6,7]. The performance of such bonds is inferior to the established Gold/aluminum bonds. In addition, bond pad damage can be induced in the layers beneath the pad metal also resulting in long-term reliability issues [8]. This paper will briefly review the reliability history of Gold Wire with respect to the above-mentioned mechanisms and elaborate on results of copper Wire bonding with respect to long-term reliability and potential failure mechanisms.
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effect of Wire size on the formation of intermetallics and kirkendall voids on thermal aging of thermosonic Wire bonds
Materials Letters, 2004Co-Authors: S Murali, Narasimalu Srikanth, Charles J VathAbstract:Abstract Thermosonic bonding process is a viable method to make reliable interconnections between die bond pads and leads using thin Gold and copper Wires. This paper investigates interface morphology and metallurgical behavior of the bond formed between Wire and bond pad metallization for different design and process conditions such as varying Wire size and thermal aging periods. Under thermal aging, the fine pitch Gold Wire ball bonds (0.6- and 0.8-mil-diameter Wires) show formation of Kirkendall voids apart from intermetallic compound growth. With 1- and 2-mil-diameter Gold Wire bonds, the void growth is less significant and reveals fine voids. Studies also showed that void formation is absent in the case of thicker 3-mil Wire bonds. Similar tests on copper ball bonds show good diffusional bonding without any intermetallic phase formation (or with considerable slow growth) as well as no voids on the microscopic scale and thus promises to be a better design alternative for elevated temperature conditions.
Xinliang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Bandwidth improvement for germanium photodetector using Wire bonding technology.
Optics express, 2015Co-Authors: Guanyu Chen, Shupeng Deng, Lei Liu, Xinliang ZhangAbstract:We demonstrate an ultrahigh speed germanium photodetector by introducing Gold Wires into the discrete ground electrodes with standard Wire bonding technology. To engineer the parasitic parameter, the physical dimension of the Gold Wire used for Wire bonding is specially designed with an inductance of about 450 pH. Simulation and experimental results show that the bandwidth of the photodetector can be effectively extended from less than 30 GHz to over 60 GHz.
Chunqing Wang - One of the best experts on this subject based on the ideXlab platform.
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comparison of interface evolution of ultrasonic aluminum and Gold Wire wedge bonds during thermal aging
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Chunqing Wang, Han Sur Bang, Hee Seon BangAbstract:Ultrasonic Gold and aluminum Wire wedge bonding are widely used for electrical and signal interconnections of the integrated circuit chip packages. In this paper, based on the metallurgical theories and thermal aging test methods, the long-term thermal reliabilities of Gold and aluminum Wire wedge bonding on aluminum and Au/Ni/Cu pads, were investigated, respectively. At 200 ◦ C, the Au/Al bond interfaces evolved little when the storage time was less than 48 h; with the aging time increasing, the interfacial intermetallic compounds (IMC) grew up from the pad (vertical growth); the primary compounds were Au5Al2 near the bond toe and heel, and Au2Al at the periphery. Then, the thickness of IMC was unchanged, and extended horizontally (lateral growth), Au5Al2 transformed into more stable Au2Al phase, furthermore, cracks ran through the interface of the Gold and IMC because of severe Kirkendall voids. However, Al/Au bond was more stable, and the IMC grew slowly. The purple plague AuAl2 resulted in interfacial cracks. Moreover, the bond Wire was filled with cavities.
Wei Qin - One of the best experts on this subject based on the ideXlab platform.
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an all solid state potentiometric microelectrode for detection of copper in coastal sediment pore water
Sensors and Actuators B-chemical, 2019Co-Authors: Guangtao Zhao, Rongning Liang, Feifan Wang, Jiawang Ding, Wei QinAbstract:Abstract Potentiometric microelectrodes are regarded as promising probes for ion sensing when only limited sample volumes are available. In this work, an all-solid-state ion-selective microelectrode (ISμE) has been developed by coating ionophore-based ion-selective membrane on a poly(3,4-ethylenedioxythiophene)-poly(sodium 4-styrenesulfonate) modified Gold Wire with a diameter of 14 μm for detection of copper. Under the optimized conditions, the proposed all-solid-state Cu2+-ISμE shows a Nernst response toward Cu2+ in 0.5 M NaCl in the range from 2.5 × 10−7 to 2.5 × 10−4 M with a detection limit of 4.0 × 10−8 M. Additionally, the Cu2+-ISμE has been used for monitoring the vertical distribution profile of Cu2+ in coastal sediment pore water with a small volume (e.g., 300 μL). The results agree well with those obtained by anodic stripping voltammetry, which indicates that the proposed potentiometric technique based on the all-solid-state ISμE is promising for detection of Cu2+ in coastal sediment pore water. The method for the preparation of the ISμE can be extended to detect other heavy metal ions in sediments by using different ion-selective membranes.
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all solid state polymeric membrane ion selective miniaturized electrodes based on a nanoporous Gold film as solid contact
Analytical Chemistry, 2014Co-Authors: Tanji Yin, Dawei Pan, Wei QinAbstract:A new type of all-solid-state polymeric membrane ion-selective electrodes (ISEs) is developed by using a nanoporous Gold (NPG) film as solid contact. The NPG film is in situ formed on the surface of a Gold Wire electrode by the multicyclic electrochemical alloying/dealloying method. The characteristics of the NPG film, such as the large surface area, high double layer capacitance, and good conductivity, have been demonstrated by cyclic voltammetry and electrochemical impedance spectroscopy. The NPG film offers a well-defined interface between the electronic conductor and the ion-selective membrane. The NPG film-based all-solid-state K+ ISE shows a stable Nernstian response within the concentration range from 10–6 to 10–2 M, and the detection limit is 4.0 × 10–7 M. The proposed electrode exhibits an improved potential stability with a reduced water layer in comparison with the coated-Wire K+-ISE, which is due to the bicontinuous electron- and ion-conducting properties of the ionophore-doped polymeric membr...