Most of the microelectromechanical systems inertial switches developed in recent years are intended for shock and impact sensing above 40 g. These switches are fabricated based on non-silicon surface micromachining with multiple steps of electroplating. In this reported work, a silicon-based low-g inertial switch typically used for linear acceleration sensing was conceived, designed and fabricated. The developed inertial switch consists of a high volume proof mass and low stiffness spiral spring, and is fabricated in a specially designed double-buried layer silicon-on-insulator wafer, with standard silicon micromachining. The measurement results show that the threshold value is about 7.42 g and the stiffness is about 1.5 N/m, in accordance with the finite element method calculation.
Purpose
Au stud bump bonding technology is an effective means to realize heterogeneous integration of commercial chips in the 2.5D electronic packaging. The purpose of this paper is to study the long-term reliability of the Au stud bump treated by four different high temperature storage times (200°C for 0, 100, 200 and 300 h).
Design/methodology/approach
The bonding strength and the fracture behavior are investigated by chip shear test. The experiment is further studied by microstructural characterization approaches such as scanning electron microscope, energy dispersive spectrometer and so on.
Findings
It is recognized that there were mainly three typical fracture models during the chip shear test among all the Au stud bump samples treated by high temperature storage. For solder bump before aging, the fracture occurred at the interface between the Cu pad and the Au stud bump. As the aging time increased, the fracture mainly occurred inside the Au stud bump at 200°C for 100 and 200 h. When aging time increased to 300 h, it is found that the fracture transferred to the interface between the Au stud bump and the Al Pad.
Originality/value
In addition, the bonding strength also changed with the high temperature storage time increasing. The bonding strength does not change linearly with the high temperature storage time increasing but decreases first and then increases. The investigation shows that the formation of the intermetallic compounds because of the reaction between the Au and Al atoms plays a key role on the bonding strength and fracture behavior variation.
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