Patent Publication Number: US-10322925-B2

Title: Shock caging features for MEMS actuator structures

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of and claims the benefit of U.S. Utility application Ser. No. 14/985,175 filed Dec. 30, 2015, titled “MEMS Actuator Structures Resistant to Shock”, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates generally to mechanical shock resistant structures for microelectromechanical systems (MEMS), and more particularly, embodiments relate to shock caging features for MEMS actuator structures. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     In accordance with various embodiments of the technology disclosed herein, structures are disclosed for caging or otherwise reducing the shock pulse experienced by MEMS device beam structures during events that may cause mechanical shock to the MEMS device. In one embodiment, a MEMS device includes a beam and a silicon caging structure that at least partially surrounds the beam. The beam has a center portion including a first end and second end, a first hinge directly coupled to the first end of the center portion, and a second hinge directly coupled to the second end of the center portion, where the first hinge and second hinge are thinner than the center portion. The silicon caging structure limits a maximum displacement of the beam in a direction perpendicular to its length. In embodiments, the beam is rigid in a direction along its length and flexible in a direction perpendicular to its length, and the beam may be between 1 and 7 millimeters long and between 10 and 70 micrometers wide. 
     In one embodiment, the beam is a conductive cantilever, and the center portion is curved and includes a point of inflection. In another embodiment, the beam is a motion control flexure, and the center portion is tapered along its length such that it is widest at its center and narrowest at its ends. 
     In one embodiment, the MEMS device includes a moving frame, and the silicon caging structure is part of the moving frame. In implementations of this embodiment, at least one of the first hinge and the second hinge is coupled to the moving frame. In further implementations of this embodiment, the silicon caging structure may include: a protrusion extending parallel to and along the length of the first hinge or the second hinge, where the protrusion limits the maximum displacement of the beam in a direction perpendicular to its length. 
     In another embodiment, the MEMS device is an actuator, the beam is a motion control flexure of the actuator, and at least one of the first hinge and the second hinge is coupled to a frame of the actuator. In implementations of this embodiment, the first hinge is coupled to a fixed frame of the actuator, and the second hinge is coupled to a moving frame of the actuator. 
     In a further embodiment, each of the first and second hinges of the beam is coupled to the center portion by a respective forked junction in a direction perpendicular to the length of the cantilever, and the respective forked junction includes a plurality of parallel beams. In an implementation of this embodiment, the silicon caging structure includes: a protrusion extending parallel to and along the length of the first hinge or the second hinge, where the protrusion limits the maximum displacement of the cantilever in a direction perpendicular to its length, and where the cantilever reaches its maximum perpendicular displacement when the protrusion contacts one of the forked junctions. 
     In yet another embodiment of the technology disclosed herein, a MEMS actuator includes: a plurality of silicon beams; and a silicon caging structure at least partially surrounding each of the plurality of silicon beams, where the silicon caging structure limits a maximum displacement of each of the plurality of silicon beams in a direction perpendicular to the silicon beam&#39;s length. In implementations of this embodiment, the MEMS actuator includes a moving frame, the moving frame includes at least a portion of the silicon caging structure, and one or more of the plurality of silicon beams is directly coupled to the moving frame. 
     As used herein, the term “about” in quantitative terms refers to plus or minus 10%. For example, “about 10” would encompass 9-11. Moreover, where “about” is used herein in conjunction with a quantitative term it is understood that in addition to the value plus or minus 10%, the exact value of the quantitative term is also contemplated and described. For example, the term “about 10” expressly contemplates, describes and includes exactly 10. 
     Other features and aspects of the disclosure will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features in accordance with various embodiments. The summary is not intended to limit the scope of the invention, which is defined solely by the claims attached hereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed technology, in accordance with one or more various embodiments, is described in detail with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict typical or example embodiments of the disclosed technology. These drawings are provided to facilitate the reader&#39;s understanding of the disclosed technology and shall not be considered limiting of the breadth, scope, or applicability thereof. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale. 
         FIG. 1A  illustrates a plan view of a comb drive in accordance with example embodiments of the disclosed technology. 
         FIG. 1B  illustrates a plan view of a bidirectional comb drive actuator including six of the comb drives of  FIG. 1A  that may use shock-resistant motion control flexures in accordance with embodiments of the disclosed technology. 
         FIG. 1C  is a magnified view of a first comb drive coupled to a second comb drive in accordance with embodiments of the disclosed technology. 
         FIG. 1D  illustrates a tapered motion control flexure for an actuator that may be used in embodiments to absorb an inertial load during mechanical shock events. 
         FIG. 1E  illustrates a design for a hinge of a motion control flexure that may be used in embodiments to reduce stress experienced by the hinges of the motion control flexure during mechanical shock events and normal operation. 
         FIG. 2A  illustrates a plan view of an MEMS actuator in accordance with example embodiments of the disclosed technology. 
         FIG. 2B  is a schematic diagram illustrating a cross-sectional view of a cantilever of the actuator of  FIG. 2A  in accordance with example embodiments of the disclosed technology. 
         FIG. 2C  illustrates a cantilever having a forked junction design that may be implemented in embodiments of the disclosed technology. 
         FIG. 2D  illustrates a cantilever having an S-shaped design that may be implemented in embodiments of the disclosed technology. 
         FIG. 2E  illustrates a cantilever having an S-shaped design and forked junction that may be implemented in embodiments of the disclosed technology. 
         FIG. 2F  illustrates an alternative embodiment of a forked junction that may be used in the cantilever of  FIG. 2E . 
         FIG. 3A  illustrates an example MEMS actuator including an outer frame, inner frame, and shock stops in accordance with the disclosed technology. 
         FIG. 3B  is a magnified view of the shock stops of the MEMS actuator of  FIG. 3A . 
         FIG. 3C  illustrates a pair of shock stops that may be implemented in embodiments of the disclosed technology. 
         FIG. 3D  illustrates a pair of shock stops that may be implemented in embodiments of the disclosed technology. 
         FIG. 4A  illustrates a plan view of a section of an example MEMS multi-dimensional actuator that utilizes shock caging structures in accordance with example embodiments of the present disclosure. 
         FIG. 4B  illustrates a shock caging structure for caging a cantilever in accordance with an embodiment of the present disclosure. 
         FIG. 4C  illustrates a shock caging structure for caging a cantilever in accordance with an embodiment of the present disclosure. 
         FIG. 4D  illustrates a shock caging structure for caging a motion control flexure in accordance with an embodiment of the present disclosure. 
         FIG. 4E  illustrates a shock caging structure for caging a motion control flexure in accordance with an embodiment of the present disclosure. 
         FIG. 5A  illustrates an example model of a mechanical shock event of a MEMS actuator including shock caging structures for its cantilevers and motion control flexures. 
         FIG. 5B  illustrates an example model of a mechanical shock event of a MEMS actuator not including shock caging structures for its cantilevers and motion control flexures. 
         FIG. 6A  illustrates an actuator with a moving frame, and an image sensor mounted on the actuator, in accordance with an embodiment of the present disclosure. 
         FIG. 6B  illustrates a package housing for covering the image sensor of  FIG. 6A , the packaging housing including shock stops for reducing the gap between the package housing and the moving frame, in accordance with an embodiment of the present disclosure. 
         FIG. 6C  illustrates a cross-section of an assembled actuator optoelectronic package, in accordance with an embodiment of the present disclosure. 
         FIG. 6D  illustrates a cross-section of an assembled actuator optoelectronic package, in accordance with an embodiment of the present disclosure. 
         FIG. 6E  illustrates a cross-section of an assembled actuator optoelectronic package, in accordance with an embodiment of the present disclosure. 
         FIG. 7  is an exploded perspective view of an example image sensor package utilized in accordance with various embodiments of the disclosed technology. 
     
    
    
     The figures are not intended to be exhaustive or to limit the invention to the precise form disclosed. It should be understood that the invention can be practiced with modification and alteration, and that the disclosed technology be limited only by the claims and the equivalents thereof. 
     DETAILED DESCRIPTION 
     In accordance with various embodiments of the disclosed technology, structures are disclosed for caging or otherwise reducing the mechanical shock pulse experienced by MEMS device beam structures during events that may cause mechanical shock to the MEMS device. The caging structures described herein may at least partially surround cantilevers, flexures, or other beam structures. This limits the motion of the beam in a direction perpendicular to the beam&#39;s longitudinal axis, thereby reducing stress on the beam and preventing possible breakage or damage in the event of a mechanical shock. 
     For example, in the event that a device (e.g., a cellphone) with an installed MEMS device is dropped from a height that may produce a significant shock force (e.g., greater than one meter), the caging structures disclosed herein may prevent damage to the beam structures of the MEMS actuator when the device hits the ground. By preventing the beams from experiencing large amplitude oscillations perpendicular to their length or otherwise moving excessively during the impact of the drop, the caging structures help reduce stress on the beam. 
     In embodiments, the disclosed shock caging structures may be used in combination with shock-resistant MEMS device structures (e.g., shock resistant beam structures). In implementations, the shock-resistant structures may reduce load on the MEMS actuator and resist deformation during events that may cause shock to the MEMS actuator. Accordingly, by implementing a combination of shock caging features with shock-resistant structures, the reliability of a MEMS device may be improved. 
       FIGS. 1-7  illustrate MEMS actuators for moving an optoelectronic device that may implement shock resistant structures in accordance with particular embodiments of the technology disclosed herein. It should be noted that although the resistant caging MEMS structures will be described primarily with reference to the example MEMS actuators of  FIGS. 1-7 , one having skill in the art would appreciate that the shock resistant structures described herein could be implemented in other MEMS apparatuses including moving beams that may be subject to mechanical shock events. 
       FIGS. 1A-1B  illustrate plan views of a comb drive  10  and bidirectional comb drive actuator  20  including six comb drives  10   a - f  in accordance with example embodiments of the present disclosure. As illustrated in  FIG. 1A , each comb drive  10  includes comb finger arrays  15  and  16 . Each comb finger array  15  and  16  includes a respective spine ( 14 ,  12 ) and plurality of comb fingers ( 13 ,  11 ). 
     Bidirectional Comb drive actuator  20  includes first and second frame pieces  22   a - 22   b , and first and second motion control flexures  24   a - 24   b . Although not shown in detail in  FIG. 1B , it will be understood that, as shown in  FIG. 1A , for each comb drive  10   a - f , comb fingers  11  and  13  extend substantially from left to right, and vice versa, in comb finger arrays  15   a - f  and  16   a - f . Moreover, it will be understood that spines  12  and  14  run substantially vertically from first frame piece  22   a  to second frame piece  22   b , i.e., substantially in parallel with motion control flexures  24   a - 24   b . This is illustrated by  FIG. 1C , which shows a first comb drive  10   b  coupled to a second comb drive  10   c.    
     As illustrated in this embodiment, spine  14  is attached to second frame piece  22   b , while spine  12  is attached to first frame piece  22   a . During operation, as comb finger arrays  15  and  16  of each comb drive  10   a - 10   f  are attracted to or repelled from one another by electrostatic forces, movement occurs such that first frame piece  22   a  likewise moves in a direction when the second frame is fixed (e.g., in the positive X direction in  FIG. 1B ). One of skill in the art will appreciate, upon studying the present disclosure, that electrostatic forces and other motive forces may be developed between each pair of comb finger arrays  15  and  16  by methods other than applying voltage, without departing from the spirit of the present disclosure. For example, charge may be applied to comb finger arrays  15  and  16 . 
     In various embodiments, spines  12  and  14  and first and second frame pieces  22   a  and  22   b  may be dimensioned wide and deep enough to be rigid and not flex substantially under an applied range of electrostatic or other motive forces. For example, in particular embodiments spines  12  and  14  may be about 20 to 100 micrometers wide and about 50 to 250 micrometers deep, and first and second frame pieces  22   a  and  22   b  may be larger than about 50 micrometers wide and about 50 to 250 micrometers deep. 
     In one embodiment, during operation of comb drive actuator  20 , when comb finger arrays  15   a  and  16   a  are electrified (e.g., in the manner described above), a motive force is applied with respect to first and second frame pieces  22   a - 22   b  such that either first or second frame piece  22   a - 22   b  moves substantially horizontally from an initial position with respect to second or first frame piece  22   a - 22   b , depending upon which of first and second frame piece  22   a - 22   b  is mechanically fixed. Once comb finger arrays  15   a  and  16   a  are no longer electrified, first or second frame pieces  22   a - 22   b  move back to the initial state due to the spring restoring force of first and second motion flexures  24   a  and  24   b . Further to this implementation, movement in a substantially opposite direction is achieved (e.g., in the opposite X direction in  FIG. 1B ), in addition to the movement resulting from comb drive  10   a , when comb finger arrays  15   c  and  16   c  of comb drive  10   c  are electrified. Likewise, bidirectional movement in these two directions (i.e., positive and negative X direction in the drawing) may be achieved by electrifying the comb finger arrays of comb drives  10   b ,  10   d , and  10   e - f.    
     In various embodiments, spines  12  and  14  of comb finger arrays  15   a - f  and  16   a - f  may be attached to first and/or second frame pieces  22   a - b  in different configurations to achieve different purposes. For example, in one embodiment, for each comb drive  10   a - 10   f , spine  12  is attached to first frame piece  22   a  while spine  14  is attached to second frame piece  22   b . Such a configuration results in a parallel cascade of comb drives  10   a - f  that may increase the electrostatic force ultimately applied to first and second frame pieces  22   a - b . In another example embodiment, comb drives  10   a - 10   f  are arranged in a back-to-back fashion to achieve bidirectional movement, as described above. While this back-to-back arrangement was described above with regard comb drives  10   a - f —i.e., six comb drives  10 —a different number of comb drives may be used to achieve bidirectional movement. 
     In one embodiment, a comb finger array, for example,  16   a ,  16   c ,  16   e  or  15   b ,  15   d ,  15   f  of each comb drive  10   a - 10   f  may be tied to a common potential (e.g., ground or some other positive or negative voltage) that acts as a reference for the other three comb finger arrays. Given this reference, the comb finger arrays that are not tied to a common potential may be electrified depending upon the direction of movement required. 
     For example, consider an embodiment where comb finger arrays  15   a ,  16   b ,  15   c ,  16   d ,  15   e  and  15   f  of comb drives  10   a - 10   f  are tied to a common ground. In this embodiment, movement of comb drive actuator  20  may be effectuated by applying a positive or negative voltage (e.g., relative to ground or other common reference) to comb finger array  16   a , hence causing comb finger array  16   a  to be attracted to comb finger array  15   a . Assuming second frame piece  22   b  is fixed, this attraction would, in this example, cause first frame piece  22   a  to move to the left in  FIG. 1B . Further to this illustration, electrifying comb finger array  15   b  may entail applying thereto a positive or negative voltage  15   b , hence causing comb finger array  15   b  to be attracted to comb finger array  16   b . This attraction would, in this instance, cause first frame piece  22   a  to move to the right in  FIG. 1B , assuming again that second frame piece  22   b  is fixed. 
     In further embodiments, the motive force developed by a comb drive  10   a  may differ from the motive force developed by another comb drive  10   b - 10   f . For example, voltages of different magnitudes may be applied to some or all of comb finger arrays  15   b ,  15   d , and  15   f , or whichever comb finger arrays are not tied to a common potential. In some embodiments, for comb finger arrays  15   b ,  15   d , and  15   f  to maintain different voltage levels, or electrostatic or charge states, the comb finger arrays may be electrically separate (or isolated) from one another. 
     The movement of first or second frame pieces  22   a - 22   b  and comb finger arrays  15   a - f  or  16   a - f  of each comb drive  10   a - 10   f  may be directed and/or controlled to some extent by first and second motion control flexures  24   a - 24   b . In this particular embodiment, for example, first and second motion control flexures  24   a - 24   b  are substantially flexible or soft in the horizontal direction (i.e., in the direction of comb fingers  11  and  13 ) and substantially stiff or rigid in the vertical direction (i.e., in the direction of spines  12  and  14 ). Accordingly, first and second motion control flexures  24   a - 24   b  allow comb drive  10  to effect bidirectional movement horizontally (i.e., in the X direction  FIG. 1B ) while substantially restricting the movement in the vertical direction (i.e., in the Y direction in  FIG. 1B ). 
     The arrangement of first and second motion control flexures  24   a - 24   b  may be referred to, in some embodiments, as a double parallel flexure motion control. Such a double parallel flexure motion control may produce nearly linear motion, but there may be a slight run-out known as arcuate motion. Nevertheless, the gap on one side of comb fingers  11  may not be equal to the gap on the other side of comb fingers  11 , and this may be used advantageously in design to correct for effects such as arcuate motion of a double parallel flexure motion control. In embodiments, additional structures may be used to control the motion of first and second frame pieces  22   a - 22   b  with respect to one another. 
     In the illustrated embodiment, first and second flexures  24   a - 24   b  include thinner portions  24   a - 2  and  24   b - 2  on the respective ends thereof. These thinner portions may allow bending when, for example, there is a translation of first frame piece  22   a  with respect to second frame piece  22   b  or vice versa (i.e., in the X direction in  FIG. 1B ). In embodiments, the thicker portion  24   a - 1  and  24   b - 1  of first and second flexures  24   a  and  24   b  may be dimensioned to be about 10 to 50 micrometers (μm) wide (i.e., width in x direction of  FIG. 1B ), and the thinner portions  24   a - 2  and  24   b - 2  may be dimensioned to be about 1 to 10 μm wide. In various embodiments, any number and type of motion controls may be used as desired to control or limit the motion of comb finger arrays  15  or  16 . Controlled motion may enhance the overall precision with which comb drive actuator  20  effects movement, or positions a device such as, for example, an image sensor in a smartphone camera. In addition, controlled motion aids in avoiding a situation in which comb fingers  11  and  13  snap together. For example, controlled motion may generally be effected by creating a lower level of stiffness in desired direction of motion of comb fingers  15  and  16 , while creating a higher level of stiffness in all undesired degrees of freedom, especially in the direction orthogonal to the motion of comb fingers  15  and  16  in the plane of comb drive actuator  20 . By way of example, this may be done using a double parallel flexure type motion control. 
     In various embodiments, motion control flexures  24   a  and  24   b  may be designed to improve the shock performance of a MEMS actuator device. In such embodiments, motion control flexures  24   a  and  24   b  may be designed to absorb a force or load during a shock event (e.g., dropping a device containing the MEMS actuator). For example, in particular embodiments, motion control flexures  24   a  and  24   b  may be designed to survive the inertial load due to a motion stage for the MEMS actuator (not illustrated) and at least one of the three comb array pairs ( 10   a ,  10   c ,  10   e ), and ( 10   b ,  10   d ,  10   f ). In specific implementations of these embodiments, this inertial load may be between 200 and 800 mN. 
       FIG. 1D  illustrates a particular design for a tapered motion control flexure  24  that may be used in embodiments to absorb an inertial load during shock events. In embodiments, motion control flexure  24  may survive a loading force between 100 and 400 mN before entering a buckled state (i.e., before deforming). 
     As shown, motion control flexure  24  includes two thin, soft hinges  24 - 2  and a wide, stiff rod  24 - 1  connecting the two hinges. In embodiments, rod  24 - 1  may be between 1 and 4 millimeters (mm) long in the x direction and between 10 and 50 μm wide in the y direction. In embodiments, hinges  24 - 2  may be between 0.05 and 0.3 mm long in the x direction and between 1 and 10 μm wide in the y direction. In these embodiments, the dimensions of hinges  24 - 2  may be optimized to achieve a required stiffness or to avoid buckling. As shown in this particular embodiment, rod  24 - 1  is tapered along its length such that it is widest at its center and narrowest at it ends. This tapered design, in some embodiments, permits motion control flexure  24  to survive a larger loading force before entering a buckled state. In particular implementations of this embodiment, tapered rod  24 - 1  may be between 35 and 50 μm wide at its center and between 20 and 40 μm wide at its ends. In one particular embodiment, stiff-rod  24 - 1  is about 50 μm wide at its center, about 35 μm wide at its end, and capable of taking an inertial load of about 280 mN before buckling. In alternative embodiments, stiff-rod  24 - 1  may be uniformly wide along its entire length. 
       FIG. 1E  illustrates a particular design for hinge  24 - 2 ′ for a motion control flexure (e.g., flexure  24 ) that may be used in embodiments to reduce stress experienced by the hinges of the motion control flexure during shock events and normal operation. As illustrated, hinge  24 - 2 ′ is tapered along its length such that it is narrowest at its center and widest at its ends (in the y direction). For example, hinge  24 - 2 ′ may be about 5 μm wide at its center and about 6 μm wide at its ends (in the y direction). Although not shown in  FIG. 1E , hinge  24 - 2 ′ is also tapered in the z direction such that it is thickest at its ends and thinnest at its center. In other words, hinge  24 - 2 ′ has a three-dimensional hourglass geometry. The hourglass geometry increases the amount of material on the end portions of hinge  24 - 2 ′ (e.g., the ends connected to the actuator and rod of the flexure) while reducing the amount of material on the center portion of hinge  24 - 2 ′. As the end portions of hinge  24 - 2 ′ tend to be the weakest portions of the motion control flexure, the hourglass geometry may redistribute the stress experienced during a shock event, resulting in a more durable flexure. 
       FIG. 2A  illustrates a plan view of an example MEMS multi-dimensional actuator  40  in accordance with example embodiments of the present disclosure. As illustrated in this embodiment, actuator  40  includes an outer frame  48  (divided into four sections) connected to inner frame  46  by one or more spring elements or flexures  80 , four bidirectional comb drive actuators  20   a - d , and one or more cantilevers  44   a - d  including a first end connected to one end of comb drive actuators  20   a - d  and a second end connected to inner frame  46 . Although  FIG. 2A  illustrates an example actuator  40  including four comb drive actuators  20 , in other embodiments, actuator  40  may include a different number of comb drive actuators  20 . 
     In embodiments, actuator  40  includes an anchor  42  that is rigidly connected or attached to first and/or second frame pieces  22   a - 22   b  of one or more comb drive actuators  20 , such that anchor  42  is mechanically fixed with respect thereto. Thus, for example, if first frame piece  22   a  is attached to anchor  32 , movement of second frame piece  22   b  relative to first frame piece  22   a  may also be considered movement relative to anchor  42 . 
     During operation of actuator  40 , comb drive actuators  20   a - d  may apply a controlled force between inner frame  46  and anchor  42 . One or more comb drive actuators  20   a - d  may be rigidly connected or attached to anchor  42 , and anchor  42  may be mechanically fixed (e.g., rigidly connected or attached) with respect to outer frame  48 . In one embodiment, a platform is rigidly connected or attached to outer frame  48  and to anchor  42 . In this manner, the platform may mechanically fix outer frame  48  with respect to anchor  42  (and/or vice versa). Inner frame  46  may then move with respect to both outer frame  48  and anchor  42 , and also with respect to the platform. In one embodiment, the platform is a silicon platform. The platform, in various embodiments, is an optoelectronic device, or an image sensor, such as a charge-coupled-device (CCD) or a complementary-metal-oxide-semiconductor (CMOS) image sensor. 
     In embodiments, the size of actuator  40  may be substantially the same as the size as the platform, and the platform may attach to outer frame  48  and anchor  42 , thus mechanically fixing anchor  42  with respect to outer frame  48 . In another embodiment of actuator  40 , the platform is smaller than actuator  40 , and the platform attaches to inner frame  46 . In this particular embodiment, outer frame  48  is fixed (or rigidly connected or attached) relative to anchor  42 , and inner frame  46  is moved by the various comb drive actuators  20   a - d.    
     In one embodiment, two comb drive actuators  20   a  and  20   d  actuate along a first direction or axis in the plane of actuator  40  (e.g., east/west, or left/right), and two comb drive actuators  20   b  and  20   c  actuate along a second direction or axis in the plane of actuator  40  (e.g., north/south, or top/bottom). The first and second directions may be substantially perpendicular to one another in the plane of actuator  40 . 
     Various other configurations of comb drive actuators  20   a - d  are possible. Such configurations may include more or less comb drives  10  in each of the comb drive actuators  20   a - d , and various positioning and/or arrangement of comb drive actuators  20   a - d , for example, to enable actuation in more or less degrees of freedom (e.g., in a triangular, pentagonal, hexagonal formation, or the like). 
     In embodiments, cantilevers  44   a - d  are relatively stiff in the respective direction of motion of the respective comb drive actuators  20   a - d , and are relatively soft in the in-plane orthogonal direction. This may allow for comb drive actuators  20   a - d  to effect a controlled motion of inner frame  46  with respect to anchor  42  and hence with respect to outer frame  48 . In embodiments, illustrated by  FIG. 2A , outer frame  48  is not continuous around the perimeter of actuator  40 , but is broken into pieces (e.g., two, three, four, or more pieces). Alternatively, in other embodiments, outer frame  48  may be continuous around the perimeter of actuator  40 . Similarly, inner frame  46  may be continuous or may be divided into sections. 
     In various embodiments, electrical signals may be delivered to comb drive actuators  20   a - d  via routing on or in cantilevers  44   a - d . In some instances, two or more different voltages may be used in conjunction with comb drive actuator  20   a . In such instances, two electrical signals may be routed to comb drive actuator  20   a  via first and second conductive layers  45  and  47 , respectively, of cantilever  44   a . Once delivered to comb drive actuator  20   a , the two electrical signals may be routed, for example, via first frame piece  22   a , to comb finger arrays  16   a  and  15   b , respectively. 
     In another example implementation of actuator  40 , two electrical signals used to develop motive forces in comb drive actuator  20   b  may also be used to develop similar motive forces in comb drive actuator  20   c . In such an implementation, rather than routing these two electrical signals to comb drive actuator  20   c  through cantilever  44   c , the two electrical signals may be routed to comb drive actuator  20   c  from comb drive actuator  20   b . By way of example, this may entail routing the two electrical signals from an electrical contact pad  84 , through cantilever  44   b  to a first frame piece  22   a  of comb drive actuator  20   b . In addition, the two electrical signals may be routed from first frame piece  22   a  via flexures  24   a - b  (respectively) and second frame piece  22   b  to anchor  42 . The two electrical signals may then be routed through anchor  42  to comb drive actuator  20   c . It will be appreciated that various routing options may be exploited to deliver electrical signals to comb drive actuators  20   a - d . For example, multiple routing layers may be utilized in anchor  42 , in first or second frame pieces  22   a/b , and/or in first and second flexures  24   a/b.    
       FIG. 2B  is a schematic diagram illustrating a cross-sectional view of a portion of a cantilever  44  in accordance with example embodiments of the present disclosure. As illustrated in  FIG. 2B , cantilever  44  includes first and second conductive layers  45  and  47 , and first and second insulating layers  43  and  49 . First and second conductive layers  45  and  47  may, in some example implementations, serve as routing layers for electrical signals, and may include polysilicon and/or metal. Insulating layers  43  and  49  may provide structure for first and second conductive layers  45  and  47 . In alternative embodiments of cantilever  44 , the order of the conductive and insulating layers may be switched such that layers  43  and  49  are conductive layers and layers  45  and  47  are insulating layers. 
     In one example implementation of cantilever  44 , insulating layers  43  and  49  include silicon dioxide, second conductive layer  47  includes metal, and first conductive layer  45  includes polysilicon. In a variant of this example, a coating (e.g., oxide or the like) may cover second conductive layer  47 , e.g., to provide insulation against shorting out when coming into contact with another conductor. Second insulating layer  49  may be a thin layer that includes oxide or the like. Additionally, first conductive layer  45 , in some instances, may be relatively thick (compared to the other layers of cantilever  44 ), and may, for example, include silicon, polysilicon, metal, or the like. In such instances, first conductive layer  45  may contribute more than the other layers to the overall characteristics of cantilever  44 , including, for example, the nature, degree, or directionality of the flexibility thereof. 
     Additional embodiments of cantilever  44  (and cantilevers  44   a - d ) may include additional conductive layers, such that additional electrical signals may be routed via the cantilever  44 . In some embodiments, cantilevers  44   a - d  may be manufactured in a similar fashion to flexures  24   a - 24   b , though the sizing may be different between the two. Moreover, as would be appreciated by one having skill in the art, additional materials may be used to form the various layers of cantilever  44 . 
     In various embodiments, outer cantilevers  44  may be designed to be resistant to mechanical shock events (e.g., in the event a device including MEMS actuator  40  is dropped). In such embodiments, each cantilever  44  may be designed such that it i) experiences less displacement stress during shock; ii) experiences less radial stiffness during shock; and iii) withstands a high load without buckling. In some embodiments, outer cantilevers  44  may be designed such that they experience a peak stress of less than about 1900 MPa along their length, and less than about 2100 MPa along their width, in the event of a shock  FIGS. 2C-2F  illustrate four example designs of shock-resistant outer cantilevers that may be implemented in embodiments of the disclosure. 
       FIG. 2C  illustrates an outer cantilever  44   e  having a forked junction design. As shown, cantilever  44   e  includes a forked junction  44   e - 1  at its center. The forked-junction  44   e - 1  at the center includes an aperture  44   e - 2  and is wider (in Y direction) than the sides  44   e - 3  of outer cantilever  44   e . In various embodiments, the width (in Y direction) of aperture  44   e - 2  is between 0.02 and 0.04 millimeters, the maximum width of the forked junction  44   e - 1  is between 0.06 and 0.12 millimeters, and the width of sides  44   e - 3  is between 0.012 and 0.050 millimeters. In further embodiments, the total length (in X direction) of cantilever  44   e  is between 4.5 and 7 millimeters. In alternative embodiments, cantilever  44   e  may include additional forks (and hence apertures) at its center (e.g. 3, 4, etc.). 
       FIG. 2D  illustrates an outer cantilever  44   f  having an S-shaped design. It should be noted that although cantilever  44   f  primarily appears straight along its length in  FIG. 2D , it is curved and has a point of inflection (hence the “S-shape”) along its length that improves resilience in the event of a mechanical shock by adding flexibility to cantilever  44   f . In this embodiment, the two roots or connecting ends  44   f - 1  of cantilever  44   f  couple to a center portion  44   f - 3  via a thinner portion or hinge  44   f - 2 . Cantilever  44   f  is widest (in Y direction) at its roots  44   f - 1  and narrowest at the junction  44   f - 2  between roots  44   f - 1  and center portion  44   f - 3 . In various embodiments, the total length (x 1 ) of cantilever  44   f  is between 4.5 and 7 millimeters, and the width (y 1 ) of center portion  44   f - 3  is between 0.012 and 0.030 millimeters. 
       FIG. 2E  illustrates an outer cantilever  44   g  having the S-shaped design of cantilever  44   f  and the added feature of a “toothbrush” shaped or forked junction  44   g - 1  at each end for relieving stress on cantilever  44   g . As illustrated, outer cantilever  44   g  includes a center portion  44   g - 3  with ends coupled to end portions  44   g - 4  that attach to roots  44   g - 2 . In various embodiments, the total length (x 1 ) of cantilever  44   g  is between 4.5 and 7 millimeters, and the width (y 2 ) of center portion  44   g - 3  is between 0.012 and 0.030 millimeters. 
     The forked junction  44   g - 1  couples each end of center portion  44   g - 3  to a respective end portion  44   g - 4  in a direction perpendicular (i.e., Y direction) to the length of cantilever  44   g . Each junction  44   g - 1  includes a plurality of beams  44   g - 5  that give the junction  44   g - 1  the appearance of a toothbrush. Although each junction  44   g - 1  is illustrated as having thirteen beams  44   g - 5  in this embodiment, in alternative embodiments the number of beams  44   g - 5  may be decreased or increased (e.g., from 2 to 15) to improve the performance of cantilever  44   g  during a mechanical shock event (e.g., by reducing peak stress). As illustrated in this particular embodiment, in one junction the end portion  44   g - 4  is below (Y direction) its corresponding center portion  44   g - 3 , and in the other junction the end portion  44   g - 4  is above (Y direction) its corresponding center portion  44   g - 3 . Also illustrated in this particular embodiment, the root  44   g - 2  attached to the end portion  44   g - 4  by hinge  44   g - 6  below the center portion  44   g - 3  points upward, whereas the other root  44   g - 2  points downward. In particular embodiments, the total width (y 1 ) of a forked junction  44   g - 1 , including the end of center portion  44   g - 3 , end portion  44   g - 4 , and beams  44   g - 5 , is between 0.040 and 0.150 millimeters. 
       FIG. 2F  illustrates an alternative embodiment of a forked junction  44   g - 1 ′ that may be used in place of forked junction  44   g - 1  in cantilever  44   g  to relieve stress. As illustrated in this particular implementation, the end  44   g - 3 ′ of the center portion of cantilever  44   g  is tapered along its length (X direction) such that its width (Y direction) decreases in a direction toward the root (not shown) of the cantilever. The end  44   g - 3 ′ attaches to a corresponding tapered end portion  44   g - 4 ′ that is tapered along its length such that its width decreases in a direction away from the root. Because the width (Y direction) of the two ends  44   g - 4 ′ and  44   g - 3 ′ is substantially less along their junction point, this tapered design permits a greater length of beams  44   g - 5 ′ in a direction roughly perpendicular to cantilever  44   g  (Y direction). 
     A hinge  44   g - 6 ′ extends from a root (not shown) and connects to forked junction end  44   g - 4 ′. In embodiments, hinge  44   g - 6 ′ may have the same three-dimensional hourglass geometry as described above with respect to hinge  24 - 2 ′ of  FIG. 1E . As the junctions connecting hinge  44   g - 6 ′ to the cantilever root and end  44   g - 4 ′ may be the weakest portions of the outer cantilever, the hourglass geometry may redistribute the stress experienced during a shock event, resulting in a more durable cantilever. In embodiments, hinge  44   g - 6 ′ may be about 5 μm wide at its center and about 6 μm wide at its ends (in the y direction), and about 0.2 mm long (in the x direction). 
     Referring back to  FIG. 2A , actuator  40  includes one or more flexures or spring elements  80  connecting inner frame  46  to outer frame  48 . Flexures  80  may be electrically conductive and may be soft in all movement degrees of freedom. In various embodiments, flexures  80  route electrical signals between electrical contact pads  82  on outer frame  48  to electrical contact pads  84  on inner frame  46 . These electrical signals may subsequently be routed to one or more comb drive actuators  20  through one or more cantilevers  44   a - 44   d . In example implementations, flexures  80  come out from inner frame  46  in one direction, two directions, three directions, or in all four directions. 
     In one embodiment, actuator  40  is made using MEMS processes such as, for example, photolithography and etching of silicon. Actuator  40 , in some cases, moves +/−150 micrometers in plane, and flexures  80  may be designed to tolerate this range of motion without touching one another (e.g., so that separate electrical signals can be routed on the various spring elements  80 ). For example, flexures  80  may be S-shaped flexures ranging from about 1 to 5 micrometers in thickness, about 1 to 40 micrometers wide, and about 150 to 1000 micrometers by about 150 to 1000 micrometers in the plane. 
     In order for flexures  80  to conduct electricity well with low resistance, flexures  80  may contain, for example, heavily doped polysilicon, silicon, metal (e.g., aluminum), a combination thereof, or other conductive materials, alloys, and the like. For example, flexures  80  may be made out of polysilicon and coated with a roughly 0.2˜1 micrometer thick metal stack of Aluminum, Nickel, and Gold. In one embodiment, some flexures  80  are designed differently from other flexures  80  in order to control the motion between outer frame  48  and inner frame  46 . For example, four to eight (or some other number) of flexures  80  may have a thickness between about 10 and 250 micrometers. Such a thickness may somewhat restrict out-of-plane movement of outer frame  48  with respect to inner frame  46 . 
     In particular embodiments, flexures  80  are low stiffness flexures that operate in a buckled state without failure, thereby allowing the stiffness of the flexures to be several orders of magnitude softer than when operated in a normal state. In these embodiments, a buckled section (i.e., flexible portion) of flexures  80  may be designed such that a cross section of the flexible portion along its direction of bending (i.e., thickness and width) is small, while its length is relatively long. Particular embodiments of flexures  80  are described in greater detail in U.S. patent application Ser. No. 14/677,730 titled “Low Stiffness Flexure”, filed Apr. 2, 2015. 
     As noted above with respect to  FIG. 2A , a MEMS actuator may be designed with an outer frame  48  coupled to an inner frame  46  by a plurality of flexures  80 . During operation, inner frame  46  may collide with outer frame  48  in the event of a sudden shock. Accordingly, in embodiments, shock stops may be included in the outer and inner frames to protect the MEMS actuator structure in the event of shock. 
       FIGS. 3A-3B  illustrate one such embodiment of a MEMS actuator  100  including shock stops. As illustrated in this particular embodiment, MEMS actuator  100  comprises an inner frame  110  and an outer frame  120  that may be coupled by a plurality of flexures (not pictured). As shown in this embodiment, outer frame  120  includes four electrical bars  121 - 124 . In other embodiments outer frame  120  may be one piece. A pair of shock stops  127  and  111  corresponding to outer frame  120  and inner frame  110 , respectively. In this particular embodiment of actuator  100 , four pairs of shock stops  127  and  111  (one for each corner) are present to absorb kinetic energy of shock collisions between outer frame  120  and inner frame  110  in the event of a shock. However, as would be appreciated by one having skill in the art, any number of shock stop pairs could be implemented in alternative implementations of a MEMS actuator or other MEMS device that experiences collisions between two portions of the device. 
     In various embodiments, shock stops  127  and  111  may be designed to maximize the amount of kinetic energy they can absorb upon impact (e.g., when horizontal or vertical stop  127  collides with stop  111 ) due to a shocking event without experiencing permanent deformation. For example, in embodiments shock stops  127  and  111  may be designed to absorb a combined kinetic energy of between 100 and 400 μJ. In particular embodiments, shock stops  127  and  111  may absorb a combined kinetic energy of between 300 and 400 μJ. 
       FIGS. 3C-3D  illustrates two exemplary designs of shock stops  127  and  111  that may be implemented in embodiments of the technology disclosed herein.  FIG. 3C  illustrates shock stops  127   a  and  111   a  comprising a plurality of circular, staggered apertures  160 . In the event of a shock, surface  127   a - 2  of stop  127   a  contacts surface  111   a - 2  of shock  111   a . As illustrated in this particular embodiment, the apertures  160  are spaced apart in a concentrated, hexagonal pattern. In various embodiments, the diameters of the circular apertures may be between 0.010 and 0.022 millimeters. In particular embodiments, the diameter of the circular apertures is about 16 μm. In particular embodiments, shock stops  127   a  and  111   a  may absorb a combined energy of about 350 μJ and each deform up to about 40 μm before breaking. In alternative implementations of shock stops  127   a  and  11   a , apertures  160  may be filled with epoxy glue or other energy absorbing material to adjust their stiffness as well as capability of absorbing energy, and/or arranged in a different pattern (e.g., triangular, rectangular, linear, or other pattern). In various embodiments, the total length (x 1 ) of shock stop  127   a  is between 0.250 and 1.000 millimeters, and the total width (y 1 ) of shock stop  127   a  is between 0.0250 and 1.000 millimeters. In various embodiments, the total length (x 2 ) of shock stop  111   a  is between 0.300 and 1.200 millimeters, and the total width (y 2 ) of shock stop  111   a  is between 0.0250 and 1.000 millimeters. 
       FIG. 3D  illustrates shock stops  127   b  and  111   b  comprising a plurality of square, staggered apertures  170 . Similar to  FIG. 3C , the apertures  170  are spaced apart in a concentrated, hexagonal pattern. In particular embodiments, shock stops  127   b  and  111   b  may absorb a combined energy of about 300 μJ and each deform up to about 15 μm before breaking. In alternative implementations of shock stops  127   b  and  111   b , apertures  170  may be filled with epoxy glue or other energy absorbing material to adjust their stiffness as well as capability of absorbing energy, and/or arranged in a different pattern (e.g., triangular, rectangular, linear, or other pattern). 
     In yet further embodiments of the technology disclosed herein, other alternative shock stop designs may be implemented to tune the maximum energy they can absorb and the maximum amount of distance they may displace without breaking. For example, horizontal or vertical slits may be used instead of or in combination with the aforementioned apertures. 
       FIG. 4A  illustrates a plan view of a section of an example MEMS multi-dimensional actuator  200  that utilizes shock caging structures in accordance with example embodiments of the present disclosure. As illustrated in this embodiment, actuator  200  includes four bidirectional comb drive actuators  20   a - d , and one or more cantilevers  20   a - d  including a first end connected to one end of bidirectional comb drive actuators  20   a - d  and a second end connected to an inner frame  250 . Like actuator  40 , actuator  200  may move in multiple degrees of freedom under a control force applied by comb drive actuators  20   a - d  between inner frame  250  and a central anchor (not shown). 
     In this embodiment, actuator  200  additionally includes shock caging structures  400 ,  500 ,  600 , and  700  that limit the motion or maximum displacement of cantilevers  44   a - d  and motion control flexures  24  of comb drive actuators  20   a - d  in a direction perpendicular to their length. This limits or prevents large amplitude oscillations from occurring perpendicular to the length of the beam. In various embodiments, the shock caging structures may be solid silicon structures that do not displace substantially when they are contacted by cantilevers  44   a - d  or motion control flexures  24 . In implementations of these embodiments, the shock caging structures are shaped such that the cantilevers  44   a - d  or motion control flexures  24  contact a maximum amount of the surface area of the caging structure during a shock event. 
     As illustrated in this embodiment, actuator  200  includes four distinct shock caging configurations or structures: structures  400  and  500  for caging cantilevers  44   a - 44   d , and structures  600  and  700  for caging motion control flexures  24 . As would be appreciated by one having skill in the art, in various embodiments the shock caging structures need not be limited to the precise configurations illustrated herein, and may be implemented to limit the movement of any moving beam in a MEMS device. 
     Shock caging structures  400  and  500  limit the motion of cantilevers  44   a - 44   d  and may be formed as a part of inner frame  250  or a moving frame  22   a  of comb drive actuators  20   a - 20   d . For example, as illustrated in this embodiment, shock caging structure  400  is formed as part of a moving of frame  22   a  of a comb drive actuator  20   a - 20   d  whereas shock caging structure  500  is formed as part of the inner frame  250 . 
     Shock caging structures  600  and  700  limit the motion of motion control flexures  24  and may be formed as a part of the fixed or moving frames (e.g., frame pieces  22   a - 22   b ) of comb drive actuators  20   a - 20   d . For example, shock caging structures  700  may be a part of the fixed frame  22   b  of comb drive actuators  20   a - 20   d  whereas shock caging structures  600  may be a part of the moving frame  22   a  of comb drive actuators  20   a - 20   d . The caging structures may be formed by shifting comb drive actuators  20   a - 20   d  further away from the center of the actuator. 
       FIG. 4B  illustrates a shock caging structure  400  for caging a cantilever  44  in accordance with an embodiment. Caging structure  400  (e.g., a rigid silicon structure) surrounds an end of cantilever  44 . In this embodiment, caging structure  400  is a part of a moving frame  22   a  of a comb drive actuator  20 . 
     Caging structure  400  includes a protrusion  420  above hinge  44   g - 6 ′ that extends parallel to and past the hinge. In this example, protrusion  420  terminates above end  44   g - 4 ′ of the forked junction  44   g - 1 ′. Accordingly, in the event of a shock, end  44   g - 4 ′ contacts stiff protrusion  420  and does not vertically displace in the y direction past stiff protrusion  420 . Following this configuration, the motion of thin hinge  44   g - 6 ′, which may be the weakest portion of cantilever  44 , is substantially limited during a shock event. For example, with the caging structure  400 , hinge  44   g - 6 ′ may displace about 10 times less in the y direction. In alternative embodiments, protrusion  420  may terminate above end  44   g - 3 ′ of the forked junction  44   g - 1 ′ or even further. 
     The length of protrusion  420  and the vertical gap between forked junction  44   g - 1 ′ and caging structure  420  may be tuned in various embodiments to maximize the amount of mechanical shock protection provided while ensuring that cantilever  44  has enough space to move during regular operation. In specific embodiments, protrusion  420  may be between 150 and 300 micrometers long, and the gap between end  44   g - 4 ′ and caging structure  320   b  (below or above the forked junction) may be between 3 and 20 micrometers. 
       FIG. 4C  illustrates a shock caging structure  500  for a caging a cantilever  44  in accordance with an embodiment. A caging structure  500  (e.g., a rigid silicon structure) surrounds an end of a cantilever  44 . In this embodiment, caging structure  500  is a part of inner frame  250  of actuator  200 . 
     Caging structure  500  includes a protrusion  520  below hinge  44   g - 6 ′ that extends parallel to and past the hinge. In this example, protrusion  520  terminates below end  44   g - 4 ′ of the forked junction  44   g - 1 ′. Accordingly, in the event of a mechanical shock, end  44   g - 4 ′ contacts stiff protrusion  520  and does not displace downward in the y direction past stiff protrusion  520 , or upward in the y direction past the wall of inner frame  250 . Following this configuration, the motion of thin hinge  44   g - 6 ′, which may be the weakest portion of cantilever  44 , is substantially limited during a shock event. For example, with the caging structure, hinge  44   g - 6 ′ may displace about 10 times less in the y direction. In alternative embodiments, protrusion  520  may terminate below end  44   g - 3 ′ of the forked junction  44   g - 1 ′ or even further. 
     The length of protrusion  520  and the vertical gap between forked junction  44   g - 1 ′ and caging structure  500  may be tuned in various embodiments to maximize the amount of shock protection provided while ensuring that cantilever  44  has enough space to move during regular operation. In specific embodiments, protrusion  520  may be between 150 and 300 micrometers long, and the gap between end  44   g - 4 ′ and caging structure  500  (below or above the forked junction) may be between 3 and 20 micrometers. 
       FIG. 4D  illustrates a shock caging structure  600  for caging a motion control flexure  24  in accordance with an embodiment. A caging structure  600  (e.g., a rigid silicon structure) surrounds an end of motion control flexure  24 . In this embodiment, caging structure  600  is a part of a moving frame  22   a  of a comb drive actuator  20 . 
     Caging structure  600  includes a protrusion  620  to the side of hinge  24 - 2  that extends parallel to and past the hinge. In this example, protrusion  620  terminates at an end of rod  24 - 1  of motion control flexure  24 . Accordingly, in the event of a shock, the end of rod  24 - 1  contacts stiff protrusion  620  and does not horizontally displace in the left x direction past stiff protrusion  620  or in the right x direction past frame  22   a . Following this configuration, the motion of thin hinge  24 - 2 , which may be the weakest portion of motion control flexure  24 , is substantially limited during a shock event. For example, with the caging structure  600 , hinge  24 - 2  may displace about 10 times less in the x direction. 
     The length of protrusion  620  and the horizontal gap between the end of rod  24 - 1  and caging structure  600  may be tuned in various embodiments to maximize the amount of shock protection provided while ensuring that flexure  24  has enough space to move during regular operation. In specific embodiments, protrusion  620  may be between 100 and 225 micrometers long, and the gap between rod  24 - 1  and caging structure  600  (to the left or right of the rod) may be between 4 and 20 micrometers. 
       FIG. 4E  illustrates a shock caging structure  700  for caging a motion control flexure  24  in accordance with an embodiment. A caging structure  700  (e.g., a rigid silicon structure) surrounds an end of motion control flexure  24 . In this embodiment, caging structure  700  is a part of a fixed frame  22   b  of a comb drive actuator  20 . Frame  22   b  surrounds an end of rod  24 - 1  of motion control flexure  24 . Accordingly, in the event of a shock, the end of rod  24 - 1  does not horizontally displace past the walls of the frame. Following this configuration, the motion of thin hinge  24 - 2 , which may be the weakest portion of motion control flexure  24 , is substantially limited during a shock event. 
       FIG. 5A  illustrates an example model at a moment during a mechanical shock event of a MEMS actuator including shock caging structures for its cantilevers  44  and motion control flexures  24 . The shock caging structures limit the motion experienced by cantilevers  44  and motion control flexures  24 . Less stress is placed on the hinges of cantilevers  44  and flexures  24 .  FIG. 5B  illustrates an example model at a moment during a mechanical shock event of a MEMS actuator not including shock caging structures for its cantilevers  44  and motion control flexures  24 . Without the shock caging structures, cantilevers  44  and motion control flexures  24  freely flail and oscillate between the moving frames. The hinges of cantilevers  44  and motion control flexures  24  experience greater stress. 
       FIG. 6A  is a top view illustrating an image sensor  800  mounted on a MEMS actuator  1000  including moving frame  1100 .  FIG. 6B  illustrates a package housing  900  for covering the image sensor  800  on MEMS actuator  1000 .  FIGS. 6C-6E  illustrate cross-sections of an assembled actuator optoelectronic package including the components of  FIGS. 6A-6B . As shown, package housing  900  includes shock stops  910  and  920  that reduce the gap between component  1150  of moving frame  1100  and the back of package housing  900 . Stops  910  and  920  may prevent the moving frame  1100  from moving excessively out of plane during a mechanical shock event, which may deform any motion control beams (e.g., cantilevers) of the actuator. In embodiments, the shock stops may be made of a suitable plastic. 
       FIG. 7  is an exploded perspective view illustrating an assembled moving image sensor package  55  that may use the mechanical shock reduction features described herein in accordance with one embodiment. In embodiments, moving image sensor package  55  may be a component of a miniature camera (e.g., a miniature camera for a mobile device). Moving image sensor package  55  can include, but is not limited to the following components: a substrate  73 ; a plurality of capacitors and/or other passive electrical components  68 ; a MEMS actuator driver  69 ; a MEMS actuator  57 ; an image sensor  70 ; an image sensor cap  71 ; and an infrared (IR) cut filter  72 . Substrate  73  can include a rigid circuit board  74  with a recess  65  and in-plane movement limiting features  67 , and a flexible circuit board acting as a back plate  66 . The rigid circuit board  74  may be constructed out of ceramic or composite materials such as those used in the manufacture of plain circuit boards (PCB), or some other appropriate material(s). Moving image sensor package  55  may include one or more drivers  69 . 
     Since the thermal conduction of air is roughly inversely proportional to the gap, and the image sensor  70  can dissipate a substantial amount of power between 100 mW and 1 W, the gaps between the image sensor  70 , the stationary portions of the MEMS actuator  57 , the moving portions of the MEMS actuator  57 , and the back plate  66  are maintained at less than approximately 50 micrometers. In one embodiment, the back plate  66  can be manufactured out of a material with good thermal conduction, such as copper, to further improve the heat sinking of the image sensor  70 . In one embodiment, the back plate  66  has a thickness of approximately 50 to 100 micrometers, and the rigid circuit board  74  has a thickness of approximately 150 to 200 micrometers. 
     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not of limitation. Likewise, the various diagrams may depict an example architectural or other configuration for the invention, which is done to aid in understanding the features and functionality that can be included in the invention. The invention is not restricted to the illustrated example architectures or configurations, but the desired features can be implemented using a variety of alternative architectures and configurations. Indeed, it will be apparent to one of skill in the art how alternative functional, logical or physical partitioning and configurations can be implemented to implement the desired features of the present invention. Also, a multitude of different constituent module names other than those depicted herein can be applied to the various partitions. Additionally, with regard to flow diagrams, operational descriptions and method claims, the order in which the steps are presented herein shall not mandate that various embodiments be implemented to perform the recited functionality in the same order unless the context dictates otherwise. 
     Although the invention is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations, to one or more of the other embodiments of the invention, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments. 
     Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; the terms “a” or “an” should be read as meaning “at least one,” “one or more” or the like; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future. 
     The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. The use of the term “module” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether control logic or other components, can be combined in a single package or separately maintained and can further be distributed in multiple groupings or packages or across multiple locations. 
     Additionally, the various embodiments set forth herein are described in terms of exemplary block diagrams, flow charts and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives can be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular architecture or configuration.