Fabrication and packaging of inertia micro-switch using metal-electroplating technology

Separate and non-interfering photoresist-molded metal-electroplating processes have been applied to the fabrication of inertia micro-switches and their wafer-level packaging in sealed cavities formed using eutectic bonding. The height of a switch and that of its cavity are independently controlled. The low process temperature allows eventual modular integration of switches on active substrates containing pre-fabricated electronic signal-processing circuits. The scheme also provides leads for electrical access to the sealed devices. The switches are based on a lateral mechanical resonator design responding to inertia change above a pre-determined threshold value. A simple but accurate lumped spring-mass model is developed based on analytical and numerical studies. Predictions of the behavior of switches with different geometric designs have been verified using both drop-hammer and shaker tests. Switches making over 100 million contacts have been demonstrated in room ambient.