Packaging MEMS inertial sensors at Motorola

One way of achieving a low cost package is to adopt, as much as possible, the industry standard for electronic components and tailor it to fit MEMS sensors. In the following, we describe such a package example developed at Motorola. One of many MEMS sensor products from Motorola is a z-axis sensor. Under an inertial force, the middle movable plate deforms and yields a signal of capacitance change. A wafer-level package model (a half symmetry model to reveal the microcavity for the transducer) is developed. A 4-dot process only involves glue drops at four corners of the silicon. On the top of the silicon, a thin layer of silicone gel is dispensed and cured before the final step of placing epoxy-molding compound (EMC). A FEA model illustrates the final pacakage.