Study on Bonding Interface Vibration of Thermosonic Flip Chip

A real time vibration measurement system was setup to monitor the vibration of bonding tool and flip chip in thermosonic flip chip bonding, and the vibration of chip and tool tip was studied. A laser Doppler vibration (LDV) measurement system was employed to monitor the vibration of the tool tip and chip. Firstly, laser beam was accurately focused on the flank of the chip or tool tip. And then, ultrasonic and force was introduced to the bonding system, and the vibration of chip and tool tip were recorded by the system. The vibration of the tool and chip can not be measured at the same time, so repeated experiments was carried out to make sure the measurement was not an accident, and make sure the vibration of tool tip and chip can indicate the same bonding process. By measure the vibration of the chip and tool tip with a laser Doppler vibration measure system, the "velocity breakaway" of chip was elucidate. It is noticed that this means the bonding strength formed in the bonding interface. By analyzing the vibration displacement of the chip and comparing with the vibration displacement of the tool tip, it is noticed that the chip vibrates in a "stick-slip" state after the "velocity breakaway", and the continued ultrasonic vibration may affect the formed bonding area