NDLI: Dynamics of Ultrasonic Transducer System for Thermosonic Flip Chip Bonding

Content Provider	IEEE Xplore Digital Library
Author	Zhili Long Yunxin Wu Lei Han Jue Zhong
Copyright Year	1999
Abstract	Thermosonic flip chip bonding is used in certain fine pitch IC packaging for its unique features. By using this bonding process in this paper, 1 mm times 1 mm chip with 8 gold bumps has been bonded onto a silver-coated substrate. Dynamical properties of transducer system, which is the key component for providing the ultrasonic energy, have been investigated using finite element model (FEM) and measurement using impedance analyzer and laser Doppler vibrometer (LDV). The simulation results show that the ultrasonic transducer vibrates by coupling with all excited modes, therefore resulting in complicated motions during bonding. The third axial mode, which includes 1.5 wavelengths and 3 nodes, is the dominant working vibration. However, this axial mode is severely disturbed by undesirable non-axial modes such as flexural modes. There are some other unwanted parasitic modes close to dominant mode. Measured velocities of the transducer horn show that the system vibrates under several modes simultaneously. The impedance measurements reveal additional frequencies overlapping the working frequency. All non-axial modes of the ultrasonic transducer disturb the bonding process and degrade the bonding quality. A subtle control is needed to obtain unique axial mode and stable vibration for high bonding quality.
Sponsorship	IEEE Components, Packaging, and Manufacturing Technology Society
Starting Page	261
Ending Page	267
Page Count	7
File Size	975379
File Format	PDF
ISSN	15213331
Volume Number	32
Issue Number	2
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2009-06-01
Publisher Place	U.S.A.
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Ultrasonic transducers Flip chip Bonding processes Impedance measurement Ultrasonic variables measurement Wavelength measurement Frequency Integrated circuit packaging Gold Finite element methods ultrasonic transducer Dynamical properties finite element method (FEM) analysis thermosonic flip chip bonding
Content Type	Text
Resource Type	Article
Subject	Electronic, Optical and Magnetic Materials Electrical and Electronic Engineering

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