2019 Volume 12 Pages E18-013-1-E18-013-7
This paper describes the bondability of thermosonic flip chip bonding, in which ultrasonic (US) vibration perpendicular to the interface was applied. Experiments were carried out with a device chip having 11 Au stud bumps and a ceramic substrate having Au-plated bonding pads. The stud bump was used to investigate bondability when the bump was largely deformed. The height reduction ratio of the bump was changed from 38% to 64% by changing bonding load and US amplitude. The relationship between the height reduction ratio of bump and shear strength of the bond was compared with that using US parallel to the interface. It was found that the bonding using US vibration perpendicular to the interface requires bonding load and US amplitude above a certain level to obtain high bond strength. When the height reduction ratio of the bump became bigger than 60%, bond strength of approximately 100 MPa was obtained. This strength was higher than bond strength of the bonding using US vibration parallel to the interface.