Abstract: A laser Doppler vibration (LDV) measurement system was setup to monitor the real time vibration of bonding tool and flip chip in thermosonic flip chip bonding. By analyzing the vibration of chip and comparing with the vibration of tool tip, the “stall” phenomena of chip is elucidate, which is significant critical phenomena indicating bonding states changing during bonding process. Stall means that the initial bonding strength is formed at the bonding interface. The chip was vibrated with tool tip before “stall”. After “stall”, relative movement produced between them, a part of tool energy is propagated to the bonding interface via chip and formed bonding strength, and a part of energy is consumed at the tool/chip interface friction, which caused damage to bonding strength and bonding interface structure, caused damage on the surface of chip and tool. Finally, a novel bonding parameter apply method is developed to reduce the friction and to enhance the bonding strength.

Key words: Laser Doppler vibration measurement, Thermosonic flip chip bonding, Vibration monitoring, Vibration transfer