Drop resistant MEMS actuator-imager assembly package

A MEMS actuator assembly package, comprising:

• a) an IR bracket or a glass holder;
• b) an IR filter or a glass cover attached to the IR filter or the glass holder;
• c) a MEMS actuator comprises a moving part, a fixed part and a plurality of mechanical springs;
• said moving part comprises of a rotor having a number of moving electrodes forming a first polarity of the actuator and attached to the fixed part via the plurality of mechanical springs;
• the fixed part of the MEMS actuator consists of a substrate supporting a number of MEMS fixed electrodes forming a second polarity of the MEMS actuator;
• d) a first set of flexible stoppers attached to the rotor that are spaced apart from the fixed outer periphery with a certain gap g1 and a stiffness K1;
• e) a second set of flexible stoppers attached to the rotor that are spaced apart from the fixed outer periphery with a certain gap g2 that is larger than the g1 gap and have a stiffness K2 that is larger than or equal to the K1 stiffness;
• f) a set of hard stoppers attached to the rotor and spaced with gap g3 that is larger than g1 and g2 gaps;
• g) a set of protrusions that extend vertically at the backside of the moving rotor and penetrate through the substrate via a through hole forming negative z-axis mechanical stoppers;
• h) an image sensor attached to the rotor of the MEMS actuator;
• i) a ball-grid-array (BGA) substrate with a main cavity sized to fit and receive the MEMS actuator;
• the BGA substrate contains a number of stopper cavities placed under the negative z-axis mechanical stoppers and have depth larger than the vertical stroke of the actuator along the negative direction of the z-axis;
• j) a stopper plate with a cut-out sized to fit and receive the image sensor;
• wherein the stopper plate is attached to the BGA substrate from the topside covering the main cavity and overlaps with the MEMS rotor;
• the BGA substrate may contain a MEMS driving circuit that provides voltage input to operate the MEMS actuator;
• whereby the first and second flexible stoppers along with the hard stoppers engage in a sequential manner with the moving mass in the presence of mechanical shocks along the four directions of the in-plane axes (x and y) bringing the moving mass to a complete stop;
• in the presence of mechanical shock along the positive and negative directions of the z-axis, the negative direction of the z-axis stoppers act to stop the moving mass along the negative z-axis direction by hitting the bottom surface of the BGA substrate stopper cavities;
• the stopper plate works as a flexible mechanical stopper for the moving mass along the positive direction of the z-axis.