A new 2-D FEM model is developed for a fundamental study of the time
dependent mechanical behavior of the substrate in ultrasonic consolidation. The simulation
shows that for a given vibration condition, the amplitude of contact friction stress and
displacement stabilize to a saturated state after certain number of ultrasonic cycles. With
the increased substrate height, the amplitude of contact frictional stress decreases, while
that of contact interface displacement increases. The energy density and transfer coefficient
at the contact interface with different substrate heights can be used as parameters to predict
the potential for ultrasonic bonding. The reason for the decrease in the frictional stress
and displacement at the contact interface for certain substrate height seems to be caused by
the complicated wave interference occurring in the substrate. A specific substrate geometry
generates a minimum strain state at the interface as a result of wave superposition. Such
minimum strain state is believed to have produced the “lack of bonding” defect.Mechanical Engineerin
