Deformation Behavior of Thick Aluminum Wire during Ultrasonic Bonding

Maeda, Masakatsu; Yoneshima, Yasuhiro; Kitamura, Hideki; Yamane, Keita; Takahashi, Yasuo

doi:10.2320/matertrans.md201210

Cited by 17 publications

(10 citation statements)

References 16 publications

(15 reference statements)

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“…7,8) By only applying the same static pressure as that in USW, deformation of wire cannot be achieved in the ambient atmosphere and temperature without applying ultrasonic vibration, 8) showing that the slipping motion at interface is essential for sound USW joint. It has also been reported that the scrubbing action and compressive deformation can effectively disrupt hard oxide on a soft metal (such as 0.51 nm of Al 2 O 3 on Al) rather than soft oxides on harder metal (such as NiO on Ni).…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic Weldability of Al Ribbon to Cu Sheet and the Dissimilar Joint Formation Mode

et al. 2015

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This work aims to investigate the ultrasonic weldability of Al ribbon (width 2.0 mm © thickness 0.2 mm) to Cu sheet (thickness 1.0 mm) using a WC tool of 2.0 mm © 1.0 mm (sonotrode tip size) and to understand joint formation process by examining joint microstructures and fracture behavior for different bonding times. For the selected conditions of 20 W power, 30 N clamping force, 0.10.8 s bonding time, it was found that sound lap joints could be readily obtained when the bonding time reached and exceeded 0.4 s, which fractured within Al ribbon, but not along interface, owing to the formation of dense and thin alloying layer of 2³3 µm thickness with a continuous composition gradient. When such bonding has been established, the actual slipping motion shifted upwards to the top of Al ribbon. On the other hand, both microstructure and fracture surface observations indicated that in the early stage, localized adhesion occurred accompanied by the detachment of just adhered Al part from remaining Al ribbon body, leading to a cracking (called secondary interface) within weak Al ribbon. Thus, USW of Al ribbon to Cu sheet was achieved through a series of slipping at three kinds of transient interfaces: localized adhesion at original interface and alloying of the adhered Al together with detachment within Al ribbon (forming the secondary interface); re-bonding at the secondary interface together with further bonding at original interface under resisted slipping and high frictional coefficient as a result of surface roughening by previous isolated compound formation at original interface; and final upwards shifting of slipping to the third interface between top surface of Al ribbon and tool end.

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Section: Introductionmentioning

confidence: 99%

Ultrasonic Weldability of Al Ribbon to Cu Sheet and the Dissimilar Joint Formation Mode

et al. 2015

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“…This often fluctuated, affected by the initial fixing situation. The bonding conditions of Fb = 7 N and Pu = 3 or 4 W adopted in the present study provide some fluctuation to the initial large sliding; however, these can provide stable bonding in the early, middle, and later stages [1,5,[22][23][24][25][26][27][28][29]36]. The friction slip was the dominant mechanism in the early stage.…”

Section: Discussionmentioning

confidence: 75%

“…Numerous on-line measurements and in-situ observations of temperature [3,10,18,21], interfacial frictional force (power) [9,21,[23][24][25][26][27], frictional slip (relative motion) at the bonding interface [3,9,23,24,28], ultrasonic vibration [21,[28][29][30], deformation behavior [29,31], contact resistance [32], and electrical signals from ultrasonic generators [33] during ultrasonic bonding have been performed. The on-line measurements and in-situ observations are extremely useful and informative for comprehension of ultrasonic microjoining.…”

Section: Introductionmentioning

confidence: 99%

In-Situ Observation of Adhesion Behavior During Ultrasonic Al Ribbon Bonding

et al. 2019

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In-situ observation was performed on a transparent silica substrate during ultrasonic Al ribbon bonding, using a high-speed video camera with differing frame rates, 10 4 fps and 10 3 fps, to clarify the adhesion behavior. The bonding process was observed as follows. Initially, friction slip occurred, producing multiple island streaks in the direction parallel to the ultrasonic vibration. The island streaks were formed as a scratch, due to surface waviness of the Al ribbon. Momentarily, a belt-shaped bond zone was formed at the center, normally due to the ultrasonic vibration. The island streaks could be clearly observed at 10 4 fps. However, the central belt zone was unclear and appeared translucent at 10 4 fps; although it was clear when observed at 10 3 fps. The island streaks were unclear at 10 3 fps. The positional relation of the island streaks and the central belt zone was confirmed from in-situ observation results of a twist and peel test of Al ribbon bonded to silica substrate. The central belt zone was between the island streaks and the silica substrate.

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“…Cu wires are used more often because of their low cost [11,12]. Al wires are used for wedge bonding [13][14][15]. In 2008, Al ribbon bonding began to be used for the power-electronics packaging of hybrid vehicles; e.g., insulated gate bipolar transistor modules [16].…”

Section: Introductionmentioning

confidence: 99%

“…This oxide-removing scrubbing can be facilitated by the friction slip due to ultrasonic vibration. The bond-formation in Al/Al UB needs the friction slip [14,15]. Experimental results based on transmission electron microscopy observation suggest that there was no oxide film at the central bond area [14].…”

Section: Introductionmentioning

confidence: 99%

Solid-State Microjoining Mechanisms of Wire Bonding and Flip Chip Bonding

Takahashi

Fukuda

Yoneshima

et al. 2017

Journal of Electronic Packaging

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Low-temperature microjoining, such as wire (or ribbon) bonding, tape automated bonding (TAB), and flip chip bonding (FCB), is necessary for electronics packaging. Each type of microjoining takes on various aspects but has common bonding mechanisms regarding friction slip, plastic deformation, and friction heating. In the present paper, solid-state microjoining mechanisms in Au wire (ball) bonding, FCB, Al wire bonding (WB), and Al ribbon bonding are discussed to systematically understand the common bonding mechanisms. Ultrasonic vibration enhances friction slip and plastic deformation, making it possible to rapidly obtain dry interconnects. Metallic adhesion at the central area of the bonding interface is mainly produced by the friction slip. On the other hand, the folding of the lateral side surfaces of the Au bump, Au ball, and Al wire is very important for increasing the bonded area. The central and peripheral adhesions are achieved by a slip-and-fold mechanism. The solid-state microjoining mechanisms of WB and FCB are discussed based on experimental results.

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Deformation Behavior of Thick Aluminum Wire during Ultrasonic Bonding

Cited by 17 publications

References 16 publications

Ultrasonic Weldability of Al Ribbon to Cu Sheet and the Dissimilar Joint Formation Mode

Ultrasonic Weldability of Al Ribbon to Cu Sheet and the Dissimilar Joint Formation Mode

In-Situ Observation of Adhesion Behavior During Ultrasonic Al Ribbon Bonding

Solid-State Microjoining Mechanisms of Wire Bonding and Flip Chip Bonding

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