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Interface features of ultrasonic flip chip bonding and reflow soldering in microelectronic packaging
Author(s) -
Duan JiAn,
Li Junhui,
Han Lei,
Zhong Jue
Publication year - 2007
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.2588
Subject(s) - flip chip , microelectronics , materials science , ultrasonic sensor , soldering , reflow soldering , composite material , diffusion bonding , dislocation , wire bonding , transmission electron microscopy , optoelectronics , metallurgy , chip , nanotechnology , electrical engineering , acoustics , layer (electronics) , adhesive , physics , engineering
Ultrasonic features in the bonding area are of interest for researchers in the field of microelectronic packaging. In this study, the interface characteristics of bonding were examined using an XD7100 X‐ray instrument and a transmission electron microscope (TEM). It was seen that bubbles were usually detected at the interfaces of the reflow‐soldered flip chip (FC), but they were not found at the interfaces of ultrasonically formed FC, and so ultrasonic FC bonding is more reliable than reflow soldering. The strong mechanical effect of ultrasonic vibration activates the dislocations in the crystalline metal lattice. Dislocation diffusion is more prominent than crystal diffusion when the temperature is relatively low during ultrasonic bonding, and therefore the processes of ultrasonic bonding enhance by several orders of magnitude. This indicates that the mechanism of ultrasonic bonding is different from the melting mechanism of reflow soldering. Copyright © 2007 John Wiley & Sons, Ltd.