Drop testing of micro-machined accelerometers (experimental samples) from the height of a table top shows that a moderate impact can result in targe percentage of device malfunctions (as much as 50%) which render the devices unusable. This paper is a fu st attempt at providing a detailed analysis of the consequences of dropping a micro-machined transducer structure to a solid surface. The theoretical analysis is composed of two pans: first, a micro-machined structure is treated as a single degree of freedom oscillator consisting of a mass, a spring and a dashpot, whose motion is governed by an ordinary differential equation. Then the flexibility of the micro-machined structure is examined by solving a governing partial differential equation. It was found that for a nominal micro-machined transducer structure the drop induced proof-mass travel and the deflection of the structure itself can be as large as 20% of its lateral dimension depending on the structural rigidity. The drop induced acceleration or deceleration depends on drop height as well as structural properties such as mass, spring constant, flexural rigidity, and geometrical dimensions. It is shown that a table-top drop can generate decelerations ranging from tens of thousands to hundreds of thousands of g's. (C) 2000 Elsevier Science S.A. All rights reserved.
