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Research Papers

Characterization of Joint Quality in Ultrasonic Welding of Battery Tabs

[+] Author and Article Information
S. Shawn Lee

e-mail: shawnlee@umich.edu

S. Jack Hu

Department of Mechanical Engineering,
The University of Michigan,
Ann Arbor, MI 48109

Jeffrey A. Abell

General Motors R&D Center,
Warren, MI 48090

Jingjing Li

Department of Mechanical Engineering,
University of Hawaii,
Honolulu, HI 96822

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the Journal of Manufacturing Science and Engineering. Manuscript received December 15, 2011; final manuscript received September 20, 2012; published online March 22, 2013. Assoc. Editor: Wei Li.

J. Manuf. Sci. Eng 135(2), 021004 (Mar 22, 2013) (13 pages) Paper No: MANU-11-1396; doi: 10.1115/1.4023364 History: Received December 15, 2011; Revised September 20, 2012

Manufacturing of lithium-ion battery packs for electric or hybrid electric vehicles requires a significant amount of joining, such as welding, to meet the desired power and capacity needs. However, conventional fusion welding processes, such as resistance spot welding and laser welding, face difficulties in joining multiple sheets of highly conductive, dissimilar materials to create large weld areas. Ultrasonic metal welding overcomes these difficulties by using its inherent advantages derived from its solid-state process characteristics. Although ultrasonic metal welding is well-qualified for battery manufacturing, there is a lack of scientific quality guidelines for implementing ultrasonic welding in volume production. In order to establish such quality guidelines, this paper first identifies a number of critical weld attributes that determine the quality of welds by experimentally characterizing the weld formation over time using copper-to-copper welding as an example. Samples of different weld quality were cross-sectioned and characterized with optical microscopy, scanning electronic microscopy (SEM), and hardness measurements in order to identify the relationship between physical weld attributes and weld performance. A novel microstructural classification method for the weld region of an ultrasonic metal weld is introduced to complete the weld quality characterization. The methodology provided in this paper links process parameters to weld performance through physical weld attributes.

Copyright © 2013 by ASME
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References

Lee, S. S., Kim, T. H., Hu, S. J., Cai, W. W., and Abell, J. A., 2010, “Joining Technologies for Automotive Lithium-Ion Battery Manufacturing: A Review,” ASME Conf. Proc., Vol. 1, pp. 541–549. [CrossRef]
Hu, S. J., Senkara, J., and Zhang, H., 1996, “Performance Characteristics of Resistance Spot Welds in the Automotive Industry: A Structural Point of View,” Proceedings of IBEC' 96 Body and Engineering, pp. 91–98.
Kong, C., Soar, R., and Dickens, P., 2003, “Characterisation of Aluminium Alloy 6061 for the Ultrasonic Consolidation Process,” Mater. Sci. Eng., A, 363(1–2), pp. 99–106. [CrossRef]
Kong, C., Soar, R., and Dickens, P., 2004, “Optimum Process Parameters for Ultrasonic Consolidation of 3003 Aluminium,” J. Mater. Process. Technol., 146(2), pp. 181–187. [CrossRef]
Yang, Y., Ram, G. D. J., and Stucker, B. E., 2010, “An Analytical Energy Model for Metal Foil Deposition in Ultrasonic Consolidation,” Rapid Prototyping J., 16(1), pp. 20–28. [CrossRef]
Hetrick, E., Baer, J., Zhu, W., Reatherford, L., Grima, A., Scholl, D., Wilkosz, D., Fatima, S., and Ward, S., 2009, “Ultrasonic Metal Welding Process Robustness in Aluminum Automotive Body Construction Applications,” Weld. J., 88(7), pp. 149S–158S.
Bakavos, D., and Prangnell, P. B., 2010, “Mechanisms of Joint and Microstructure Formation in High Power Ultrasonic Spot Welding 6111 Aluminium Automotive Sheet,” Mater. Sci. Eng., A, 527(23), pp. 6320–6334. [CrossRef]
Zhou, B., Thouless, M., and Ward, S., 2006, “Predicting the Failure of Ultrasonic Spot Welds by Pull-Out From Sheet Metal,” Int. J. Solids Struct., 43(25–26), pp. 7482–7500. [CrossRef]
Zhou, B., Thouless, M. D., and Ward, S., 2005, “Determining Mode-I Cohesive Parameters for Nugget Fracture in Ultrasonic Spot Welds,” Int. J. Fract., 136(1), pp. 309–326. [CrossRef]
Kim, T. H., Yum, J., Hu, S. J., Spicer, J. P., and Abell, J. A., 2011, “Process Robustness of Single Lap Ultrasonic Welding of Thin, Dissimilar Materials,” CIRP Ann., 60(1), pp. 17–20. [CrossRef]
Zhou, M., Zhang, H., and Hu, S. J., 2003, “Relationships Between Quality and Attributes of Spot Welds,” Weld. J., 82(Compendex), pp. 72S–77S.
Zhang, C., and Li, L., 2009, “A Coupled Thermal-Mechanical Analysis of Ultrasonic Bonding Mechanism,” Metall. Mater. Trans. B, 40(2), pp. 196–207. [CrossRef]
Ram, G. D. J., Robinson, C., Yang, Y., and Stucker, B., 2007, “Use of Ultrasonic Consolidation for Fabrication of Multi-Material Structures,” Rapid Prototyping J., 13(4), pp. 226–235. [CrossRef]
Cheng, X., and Li, X., 2007, “Investigation of Heat Generation in Ultrasonic Metal Welding Using Micro Sensor Arrays,” J. Micromech. Microeng., 17, pp. 273–282. [CrossRef]
Ji, H., Li, M., Kung, A. T., Wang, C., and Li, D., 2005, “The Diffusion of Ni Into Al Wire at the Interface of Ultrasonic Wire Bond During High Temperature Storage,” 6th International Conference on Electronic Packaging Technology, IEEE, pp. 377–381. [CrossRef]
Li, J., Han, L., and Zhong, J., 2008, “Short Circuit Diffusion of Ultrasonic Bonding Interfaces in Microelectronic Packaging,” Surf. Interface Anal., 40(5), pp. 953–957. [CrossRef]
Gunduz, I. E., Ando, T., Shattuck, E., Wong, P. Y., and Doumanidis, C. C., 2005, “Enhanced Diffusion and Phase Transformations During Ultrasonic Welding of Zinc and Aluminum,” Scr. Mater., 52(9), pp. 939–943. [CrossRef]
Kreye, H., 1977, “Melting Phenomena in Solid State Welding Processes,” Weld. J., 56(5), pp. 154–158.
Joshi, K. C., 1971, “The Formation of Ultrasonic Bonds Between Metals,” Weld. J., 50(12), pp. 840–848.
Zhou, M., Hu, S. J., and Zhang, H., 1999, “Critical Specimen Sizes for Tensile-Shear Testing of Steel Sheets,” Weld. J., 78(9), pp. 305S–313S.
Cáceres, C. H., Griffiths, J. R., Pakdel, A. R., and Davidson, C. J., 2005, “Microhardness Mapping and the Hardness-Yield Strength Relationship in High-Pressure Diecast Magnesium Alloy AZ91,” Mater. Sci. Eng., A, 402(1–2), pp. 258–268. [CrossRef]
de Geuser, F., Bley, F., Denquin, A., and Deschamps, A., 2010, “Mapping the Microstructure of a Friction-Stir Welded (FSW) Al-Li-Cu Alloy,” Proc. J. Phys. Conf. Ser., 247, p. 012034. [CrossRef]
Prangnell, P. B., and Heason, C. P., 2005, “Grain Structure Formation During Friction Stir Welding Observed by the `Stop Action Technique',” Acta Mater., 53(11), pp. 3179–3192. [CrossRef]
Steuwer, A., Dumont, M., Altenkirch, J., Birosca, S., Deschamps, A., Prangnell, P., and Withers, P., 2011, “A Combined Approach to Microstructure Mapping of an Al-Li AA2199 Friction Stir Weld,” Acta Mater., 59(8), pp. 3002–3011. [CrossRef]

Figures

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Fig. 1

Ultrasonic welding configuration: (a) an example of battery tab joining; (b) dimension and configuration of weld coupons; and (c) cross-section image (AA′)

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Fig. 2

Weld performance testing: (a) U-tensile test configuration and (b) maximum U-tensile load plotted against welding time for three different clamping pressures

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Fig. 3

Optical images of Cu and Ni-plated Cu weld cross-sections produced with a pressure of 50 psi, with increasing welding times (0.2 s, 0.6 s, and 1.0 s)

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Fig. 4

Knurl pattern of sonotrode (left) and its dimension (right)

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Fig. 5

Optical images of the formation process of microbonds and interfacial waves along the bonding line

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Fig. 6

Convoluted bonding line in the weld samples produced in 1.0 s weld time

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Fig. 7

Optical images of Cu and Ni-plated Cu joints produced in 0.4 s weld time: the layer of deformed material (a) overflowing into the space that does not contact with sonotrode tips and (b) starting to flow along the inclined plane

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Fig. 8

Material flow during the welding process: (a) a LVDT signal for 1.0 s process time and (b) optical images of valley areas of the sonotrode knurl pattern for different welding times ((a) 0.2 s; (b) 0.4 s; and (c) 0.6 s)

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Fig. 9

Optical images of Cu and Ni-plated Cu joints with increasing welding time: (a) as-received condition; (b) 0.2 s; (c) 0.4 s; (d) 0.6 s; (e) 0.8 s; and (f) 1.0 s

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Fig. 10

Hardness profile of weld samples for different welding times. The hardness is averaged over the peaks of the sonotrode (dots in the cross-section image).

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Fig. 11

Hardness variation in horizontal locations: (a) horizontal hardness profile of the weld cross-sections and (b) optical images for 0.4 s and 1.0 s

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Fig. 12

Hardness variation in vertical locations: (a) vertical hardness profile of the weld cross-sections and (b) optical images at the valley area of the sonotrode for 0.4 s and 1.0 s

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Fig. 13

Optical images of ultrasonically welded joints made in different weld qualities (i.e., “under,” “good,” and “over” weld)

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Fig. 14

Vertical position of sonotrode obtained from LVDT sensor (upper); percentile ratio of indentation measured from optical cross-section images (lower)

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Fig. 15

Hardness distribution of the weld samples for different weld times: (a) a schematic diagram of ultrasonically welded joint; (b) hardness profile of the weld interface; and (c) hardness profile outside of weld zone

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Fig. 16

Weld region classification: (a) a schematic diagram of weld region classification and (b) optical micrograph of an ultrasonic weld produced in 0.6 s welding time, giving an overview of classified weld regions

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Fig. 17

Optical micrograph of an ultrasonic weld produced in 1.0 s welding time with classified weld regions

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Fig. 18

Classified weld regions associated with failure types: (a) a schematic diagram indicating dimension of each weld region (TMAZ and WN) and (b) half TMAZ size and half WN size over weld time, with failed weldment images after U-tensile test

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Fig. 19

SEM images of deformed surfaces around the weld zone from the “over” weld: (a) a front view image (vibration direction: out-and-in-plane); (b) “island” features; (c) fatigue striation marks; (d) another front view image of the right hand side of image-(a); (e) crack propagations; and (f) microcracks

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Fig. 20

Correlation of weld performance with bond density and postweld thickness

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