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Li Junhui
Han Lei
Zhong Jue
College of Mechanical-Electronical
Engineering,
Central South University,
Changsha 410083, China |
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MICROSTRUCTURE
CHARACTERISTICS
AT THE BOND INTERFACE*
Abstract:
Lift-off and section characteristics at the interface of thermosonic bond are observed by using scanning electron microscope (KYKY2800) with EDS-test. Results show that the peeling underdeveloped bonds simulate a torus (or doughnut) with an unbonded central region and ridged peripheral region is bonded hardly. Inside roundness at flip chip bonding center are discovered. Bond strength is located between the severely ridged periphery and the non-adhering central area of the bond. For constant force and time, the ridged area of the bond pattern increases when more power is applied. For constant force and power, the ridged location of the bonded region moves closer to the bond center with time. Results of EDS-tests at Au-Al and Au-Ag interfaces show that Kirkendall diffusibility at Au-Ag interface occur and the diffusing speed of Au-atomic is faster than that of Ag, and that intermetallic compounds at Au-Al interface is generated possibly. And these would be helpful for further research about thermosonic bonding.
Key words:
Bonded interface Thermosonic bonding Microstructure |