Patent Publication Number: US-2022221353-A1

Title: Semiconductor force sensors

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Patent Application No. 63/136,239, filed Jan. 12, 2021, and entitled titled “Semiconductor Package Configurations For Mechanical Force Sensors,” and U.S. Provisional Patent Application No. 63/244,064, which was filed Sep. 14, 2021, and entitled “Semiconductor Package Configurations For Mechanical Force Sensors,” the contents of each being incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Force sensors are useful to detect one or more forces experienced by a member of interest. In some instances, a force sensor may be useful to detect stress, torque, compression, strain, tension, etc. experienced by the member of interest (e.g., a shaft, strut, beam). To facilitate the detection of these forces, the force sensor (or some component thereof) is mounted to the member so forces experienced by the member may be transferred to the force sensor during operations. 
     SUMMARY 
     Some examples described herein include a force sensor. In some examples, the force sensor includes a semiconductor die, and a die pad coupled to the semiconductor die, the semiconductor die configured to detect a force in the die pad. In addition, the force sensor includes a mold compound covering the semiconductor die and having an outer perimeter, a first side, and a second side opposite the first side, the outer perimeter extending between the first side and the second side, the die pad exposed out of the mold compound along the first side. Further, the force sensor includes a mounting frame engaged with the die pad along the second side of the mold compound, the mounting frame including multiple mounting pads extended outward in multiple directions from the outer perimeter. 
     In some examples, the force sensor includes a semiconductor die configured to detect a force and a mold compound covering the semiconductor die, the mold compound including an outer perimeter. In addition, the force sensor includes a die pad including a portion engaged with the semiconductor die and multiple mounting pads extended beyond the outer perimeter of the mold compound on opposite sides of the mold compound. 
     In some examples, the force sensor includes a semiconductor die configured to detect a force and a die pad coupled to the semiconductor die. In addition, the force sensor includes a mold compound covering the semiconductor die and having an outer perimeter, a first side, and a second side opposite the first side, the outer perimeter extending between the first side and the second side, the die pad exposed out of the mold compound along the first side. Further, the force sensor includes a mounting frame engaged with the die pad along the first side of the mold compound, the mounting frame having multiple mounting pads positioned outside of the outer perimeter on opposing sides of the mold compound. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a force sensor coupled to a shaft according to some examples. 
         FIG. 2A  is a perspective view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 2B  is a bottom view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 2C  is a cross-sectional view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 2D  is a cross-sectional view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 3A  is a cross-sectional view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 3B  is a cross-sectional view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 3C  is a cross-sectional view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 3D  is a cross-sectional view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 4A  is a bottom view a force sensor for mounting to a member of interest according to some examples. 
         FIG. 4B  is a bottom view a force sensor for mounting to a member of interest according to some examples. 
         FIG. 4C  is a bottom view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 5  is a cross-sectional view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 6A  is a top view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 6B  is a cross-sectional view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 6C  is a top view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 7  is a perspective view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 8  is a perspective view of a force sensor for mounted to a member of interest according to some examples 
         FIG. 9A  is a cross-sectional view of a force sensor mounted to a member of interest according to some examples. 
         FIG. 9B  is a cross-sectional view of a force sensor mounted to a member of interest according to some examples. 
         FIG. 10A  is a cross-sectional view of a force sensor for mounting to a member of interest according to some examples. 
         FIG. 10B  is a bottom view of a force sensor for mounting to a member of interest according to some examples. 
     
    
    
     DETAILED DESCRIPTION 
     A force sensor may be mounted to a member of interest for detecting (e.g., directly, indirectly) forces within the member. The force sensor is mounted to the member of interest, and forces experienced by the member may then be transferred to the force sensor via the mounting. Some mounting devices or techniques may dampen or absorb forces that are transferred from the member of interest thereby causing the force sensor to be less effective at detecting these forces during operations. Thus, mounting the force sensor to the member of interest may have a meaningful effect on the quality of data that may be obtained by the force sensor during operations. 
     Accordingly, examples described herein include force sensors including mounting frames and/or components for mounting the force sensor to a member of interest (e.g., a rotating shaft, structural beam). In some examples, the force sensors may include a semiconductor die that is secured to the member of interest via a mounting frame that is coupled to or integrated with a die pad for the semiconductor die. As is described in more detail herein, the mounting frame is configured to transfer forces from the member of interest to the semiconductor die of the semiconductor package. Thus, forces experienced by the member may be accurately and reliably detected. 
     Referring now to  FIG. 1 , a force sensor  100  according to some examples is shown mounted to a shaft  102  that is rotatable about a central or longitudinal axis  104 . The shaft  102  may be a rotating shaft of a pump, compressor, drivetrain or other mechanical system. The force sensor  100  is mounted to a mounting surface  106  which may include a planar or facetted surface that is defined on the otherwise curved outer surface  108  of shaft  102 . 
     During operations, the force sensor  100  may detect, via the engagement with mounting surface  106 , the forces experienced by the shaft  102 . For instance, the shaft  102  may experience a torque about longitudinal axis  104 , axial stress (e.g., from tension or compression along longitudinal axis  104 ), bending stress, strain, etc. These various forces and stresses that may be experienced by the shaft  102  may be collectively and generally referred to herein as “forces.” The force sensor  100  may detect (e.g., directly or indirectly) any one or more of these forces during operations thereby allowing personnel to monitor the operating conditions of the shaft  102 . 
     Referring now to  FIGS. 2A-2D , a force sensor  200  that may be the force sensor  100  of  FIG. 1  is shown according to some examples.  FIGS. 2A and 2B  show perspective and bottom views, respectively, of the force sensor  200 , and  FIGS. 2C and 2D  show cross-sectional views of force sensor  200  along sections B-B and A-A, respectively, in  FIG. 2B .  FIGS. 2A-2D  may be collectively referred to herein as “ FIG. 2 .” 
     As best shown in  FIGS. 2C and 2D , the force sensor  200  is a semiconductor package that includes a semiconductor die  202  having a device side  204  and non-device side  206  opposite the device side  204 . An active circuit  208  (or more simply “circuit  208 ”) is formed on the device side  204 . The non-device side  206  of semiconductor die  202  is secured to a die pad  209  via a die attach layer (not shown). 
     A number of passive devices  210  are coupled to the circuit  208  along device side  204 . The passive devices  210  may be coupled to circuit  208  via solder members  212  (which may be referred to as “solder bumps”). In some examples, the passive devices  210  may include capacitors, inductors, antennas, coils and/or other components that may perform a function (or functions) either independently of or along with circuit  208 . In some examples, the passive devices  210  may include an antenna and a filter that are coupled to circuit  208  and that are configured to receive and/or send wireless electronic signals to other devices (e.g., computers, semiconductor chip packages) either directly or via a network. Specifically, during operations, the antenna, formed or defined by the passive devices  210 , may transmit output signals of the force sensor  200  that may include, or be indicative of, forces detected by the force sensor  200 . 
     The circuit  208  may be coupled to conductive terminals  214  via bond wires  216 . In some examples, the conductive terminals  214  may be so-called gull-wing leads. However, the force sensor  200  may include a quad flat no-lead (QFN) package and the conductive terminals  214  may be arranged and designed for inclusion therein. 
     A mold compound  218  (e.g., a polymer or resin material) may cover the semiconductor die  202 , bond wires  216 , passive devices  210 , and a portion of the conductive terminals  214 . The mold compound  218  may protect the components of semiconductor die  202  bond wires  216 , passive components  210 , and conductive terminals  214  from the outside environment (e.g., specifically from dust, liquid, light, contaminants in the outside environment), and may prevent contact with conductive surfaces or members during operations. As used herein, the term “mold compound” includes a covering for a semiconductor die that is formed through any suitable process, such as a cavity molding operation, glob encapsulation, dam-and-fill type encapsulation, etc. 
     The mold compound  218  may include a first side  220 , a second side  222  opposite first side  220 , and an outer perimeter  224  extending between the first side  220  and the second side  222  along an axis  226  that extends through (e.g., perpendicularly through) the sides  220 ,  222 . As best shown in  FIGS. 2A and 2B , the mold compound  218  may be shaped as a rectangular parallelepiped in some examples. Accordingly, the first side  220  and second side  222  may be parallel planar surfaces that are spaced from one another along axis  226 , and the outer perimeter  224  may include four planar sides surfaces  228  that extend axially (with respect to axis  226 ) between sides  220 ,  222 . However, mold compound  218  may be formed in a variety of other three-dimensional shapes in other examples. 
     As shown in  FIG. 2D , the conductive terminals  214  may be curved or bent toward the second side  222 . In some examples, the conductive terminals  214  may be curved or bent toward the first side  220 . In some examples, the conductive terminals  214  may extend out of the mold compound along other surfaces (other than the side surfaces  228  forming the outer perimeter  224 ). For instance, the conductive terminals  214  may extend out of the mold compound  218  along the first side  220  in some examples. 
     The die pad  209  may be exposed out of the mold compound  218  along second side  222 . In particular, die pad  209  (or a face or surface thereof) may be flush or co-planar with second side  222  of mold compound  218 . Also, the die pad  209  may extend beyond the outer perimeter  224  of mold compound  218  on opposing side surfaces  228  that are opposite (e.g., radially opposite) one another about axis  226 . In particular, as best shown in  FIGS. 2A and 2B , the die pad  209  may include a pair of mounting pads  230  that are extending outward in multiple directions from the outer perimeter  224  (e.g., in radially opposite directions about axis  226 ). Thus, the die pad  209  may form a mounting frame  232  having the mounting pads  230  for securing force sensor  200  to a member of interest (e.g., mounting surface  106  on shaft  102  shown in  FIG. 1 ). The mounting pads  230  are in a common plane with the die pad  209 . 
     During operations, the mounting pads  230  may be secured to a surface of a member of interest via an adhesive, welding (e.g., ultrasonic welding), a mounting device (e.g., screw, nail, rivet, bolt, pin). Thereafter, forces experienced by the member of interest may be transferred to the circuit  208  via the mounting pads  230  of die pad  209 , and the transferred forces may then be detected by circuit  208 . In some examples, the circuit  208  may detect the transferred forces via piezoresistive changes caused in the circuit  208  by the transferred forces. The circuit  208  may then provide an output signal (which may include the detected force(s) and/or a value indicative thereof) to another electronic device via the passive devices  210  (e.g., which may include antenna(s), coil(s), capacitor(s), inductor(s) as described above). In some examples, the circuit  208  may provide an output signal to another electronic device via the conductive terminals  214  which may further be coupled to suitable conductive connectors, terminals, pads, etc. on another device, a printed circuit board, or other suitable device. 
     Without being limited to this or any other theory, by positioning mounting pads  230  outside of the outer perimeter  224  of mold compound  218 , they may be more easily accessed for securely mounting force sensor  200  to a member of interest (e.g., shaft  102  in  FIG. 1 ). Also, by extending mounting pads  230  outward from outer perimeter  224  on opposite sides (and in opposite directions) of mold compound  218 , the connection or mounting points of the force sensor  200  may be spaced (e.g., in a radial direction with respect to axis  226 ) to allow differential force measurements (e.g., for shear, strain, bending) to be more accurately transferred thereto. 
     Referring now to  FIGS. 3A-3D , examples of force sensors  300  that may be the force sensor  100  in  FIG. 1  are shown.  FIGS. 3A-3D  may be collectively referred to herein as “ FIG. 3 .” The force sensors  300  shown in  FIGS. 3A-3D  may be similar to the force sensor  200  shown in  FIGS. 2A-2D  and may include a number of the same components described above (however, some of these shared components may not be shown in  FIGS. 3A-3D  so as to simplify the drawings and the description below). 
     Referring specifically to  FIG. 3A , in some examples force sensor  300  may include semiconductor die  302  that is similar to the semiconductor die  202  described above ( FIGS. 2C and 2D ). The semiconductor die  302  is covered by a mold compound  304  that may be similar to the mold compound  218  described above ( FIGS. 2A-2D ). Also, the semiconductor die  302  may be mounted to a die pad  306  that is integrated within a mounting frame  308  that extends beyond the outer perimeter  310  of mold compound  304 . Thus, the die pad  306  and mounting frame  308  form a monolithic body that is made up of one continuous piece of material (e.g., a metallic material). 
     The mounting frame  308  includes mounting pads  312  that may function in the manner described above for mounting pads  230  ( FIGS. 2A-2D ); however, the mounting pads  312  are positioned in a different plane than other portions of the die pad  306 . In particular, the mounting frame  308  may include a portion  314  that is engaged with the semiconductor die  302  and is in a first plane  316 . The portion  314  may form the die pad  306 . Also, the mounting pads  312  of the mounting frame  308  are in a second plane  318  that is spaced from the first plane  316  along an axis  320  extending between (e.g., perpendicularly between) first and second sides  322  and  324 , respectively, of mold compound  304  (e.g., similar to axis  226  in  FIGS. 2A-2D ). The mounting frame  308  may also include connection portions  326  extending between the portion  314  and the mounting pads  312 . The portion  314  is positioned between the mounting pads  312  and the first side  322  along the axis  320 . The connections portions  326  may extend at a non-zero angle θ to the first plane  316  (and thus also the second plane  318 ). In some examples the angle θ may be about 90°. 
     During operations, the mounting pads  312  may be secured to a surface of a member of interest via an adhesive, welding (e.g., ultrasonic welding), a mounting device (e.g., screw, nail, rivet, bolt, pin), etc. Thereafter, forces experienced by the member of interest may be transferred to a circuit on the semiconductor die (e.g., circuit  208  in  FIGS. 2C and 2D ) via the mounting pads  312  of die pad  306 , and the transferred forces may then be detected as described above. Without being limited to this or any other theory, by spacing the mounting pads  312  from the portion  314  via connection portions  326 , semiconductor die  302  and mold compound  304  along axis  320 , the semiconductor die  302  may be suspended from the member of interest via the mounting frame  308 . Thus, during operations forces experienced by the member of interest (e.g., shaft  102  in  FIG. 1 ) may cause deformation of mounting frame  308  thereby magnifies forces transferred to semiconductor die  302 . Accordingly, mounting frame  308  may allow the sensitivity of force sensor  300  to be enhanced. 
     Referring specifically now to  FIG. 3B , in some examples the angle θ of the connection portions  326  is greater than or equal to 90° and less than or equal to 180°. In some example, the angle θ may be an obtuse angle that is greater than 90° and less than 180°. In some examples, the angle θ may be approximately 45°. Without being limited to this or any other theory, an acute angle θ may allow components of forces that are aligned (or parallel) with the planes  316  or  318  to be more effectively transferred to semiconductor die  302  via the mounting frame  308 . 
     Referring specifically now to  FIG. 3C , in some examples the semiconductor die  302  and the mold compound  304  may be coupled to the portion  314  to thereby place the first side  322  and the second side  324  between the mounting pads  312  and the portion  314  along axis  320 . Without being limited to this or any other theory, arrangement of the mounting frame  308 , semiconductor die  302  and mold compound  304  in the manner shown in  FIG. 3C  may allow the mounting frame to cover (at least partially) the semiconductor die  302  and mold compound  304  and therefore provide some protection to these components from impact during operations. However, the mounting frame  308  of force sensor  300  in  FIG. 3C  may continue to function as a force magnifier for the same reasons provided above. 
     Referring specifically now to  FIG. 3D , in some examples the mounting frame  308  may be separately engaged with a die pad  328  that is engaged with a device side  330  of the semiconductor die  302 . The die pad  328  may be exposed out of the mold compound  304  along second side  324  and may be engaged (e.g., welded, adhered, bolted, pinned) to the portion  314  of mounting frame  308 . Without being limited to this or any other theory, by including a separate mounting frame  308  (e.g., separate from the die pad  328 ), the manufacturing process for semiconductor die  302 , die pad  328 , and mold compound  304  may be simplified and separate from the manufacturing of mounting frame  308 , which may involve different tooling, materials, etc. Thus, an overall manufacturing process for force sensor  300  may be simplified. 
     Referring now to  FIGS. 4A-4C , examples of force sensors  400  that may be the force sensor  100  in  FIG. 1  are shown.  FIGS. 4A-4C  may be collectively referred to herein as “ FIG. 4 .” The force sensors  400  shown in  FIGS. 4A-4C  may be similar to the force sensor  200  shown in  FIGS. 2A-2D  and may include a number of the same components described above (however, some of these shared components may not be shown in  FIGS. 4A-4C  so as to simplify the drawings and the description below). 
       FIGS. 4A-4C  show examples in which the mounting pads  402  of a mounting frame  404  for attaching the force sensor  400  to a member of interest (e.g., shaft  102  in  FIG. 1 ) may be split into multiple mounting pads  402  on a side  406  (or sides  406 ) of an outer perimeter  408  of a mold compound  410  of the force sensor  400 . Referring specifically to  FIG. 4A , in some examples a portion  414  of the mounting frame  404  (which may be engaged with or integrated with a die pad of the force sensor as described above) may be a singular piece, and the mounting pads  402  outside of the outer perimeter  408  of mold compound  410  are split into multiple mounting pads  402  on the opposite sides  406 . Referring specifically to  FIG. 4B , in some examples both the mounting pads  402  and the portion  414  are split into two portions. Without being limited to this or any other theory, by splitting the mounting pads  402  and/or the portion  414 , differences in forces (e.g., shear) may transferred to the split mounting pads  402  on a given side  406  of outer perimeter  408  may be more effectively transferred through mounting frame  404  and detected by the force sensors  400 . Referring specifically to  FIG. 4C , in some examples the portion  414  may be split into more than two (e.g., four) separate pieces  416  that are each connected to a mounting pad  402  or multiple mounting pads  402  that are extended from the sides  406  of outer perimeter  408 . In some examples, each piece  416  of the portion  414  may be engaged with multiple mounting pads  402  extended from different sides  406 , or may be engaged with a single mounting pad  402  that may extend from outer perimeter  408  along multiple sides  406  such as is shown via the dotted line  418  in  FIG. 4C . 
     Referring again to  FIGS. 4A and 4C , force sensors may include conductive terminals  420  that extend out of the mold compound  410 . The conductive terminals  420  may be similar to the conductive terminals  214  shown in  FIGS. 2A-2D  and described above. 
     Referring now to  FIG. 5 , examples of a force sensor  500  that may be the force sensor  100  in  FIG. 1  is shown. The force sensor shown in  FIG. 5  may be similar to the force sensor shown in  FIGS. 2A-2D  and may include a number of the same components described above (however, some of these shared components may not be shown in  FIG. 5  so as to simplify the drawings and the description below). 
     As shown in  FIG. 5 , force sensor  500  includes a semiconductor die  502  mounted to a die pad  504  that is integrally formed within a mounting frame  506  as described above. A mold compound  508  covers the semiconductor die  502 . The mold compound  508  includes a first side  510  and a second side  512  spaced from and opposite first side  510  along an axis  514 . A portion  516  of the mounting frame  506  (and which forms the die pad  504 ) is exposed along the second side  512 . The mounting frame  506  also includes multiple mounting pads  518  that are coupled to portion  516  via connection portions  520 . As described above for the force sensor  300  shown in  FIG. 3C , the semiconductor die  502  and mold compound  508  are coupled to portion  516  to thereby place the first and second sides  510 ,  512  between the portion  516  and mounting pads  518  along the axis  514 . The connection portions  520  extend through the mold compound  508  between the portion  516  and mounting pads  518 . Accordingly, forces may be transferred from the mounting frame  506  to the semiconductor die  502  both at the engagement with semiconductor die  502  and the portion  516  and between the connection portions  520  and semiconductor die  502  via the mold compound  508 . 
     Referring now to  FIGS. 6A-6C , examples of force sensors  600  that may be the force sensor  100  in  FIG. 1  are shown. The force sensors  600  shown in  FIGS. 6A-6C  may be similar to the force sensors  200  shown in  FIGS. 2A-2D  and may include a number of the same components described above (however, some of these shared components may not be shown in  FIGS. 6A-6C  so as to simplify the drawings and the description below. 
     Force sensors  600  may include a mounting frame  604  having a portion  606  and multiple mounting pads  608  connected to the portion  606  via multiple connection portions  610 . As best shown in  FIG. 6B , the force sensor  600  also includes a semiconductor die  612  mounted to the portion  606  of mounting frame  604 . Accordingly, the portion  606  forms a die pad for the semiconductor die  612  of the force sensor  600 . Force sensor  600  also includes a mold compound  614  that covers the semiconductor die  612 . As shown in  FIG. 6A , each mounting pad  608  may be arranged or aligned along a side  616  of the outer perimeter  617  of mold compound  614  and is positioned outside of outer perimeter  617 . Accordingly, each connection portion  610  of the force sensor  600  in  FIG. 6A  extends outward from portion  606  along each side  616  of outer perimeter  617 . As shown in  FIG. 6B , in some examples each mounting pad  608  may be arranged or aligned with a corner or junction  618  of two sides  616  of the outer perimeter  617 . Accordingly, each connection portion  610  of the force sensor in  FIG. 6C  extends outward from portion  606  at a corner  618  of outer perimeter  617 . For the force sensors  600  of both  FIGS. 6A and 6C , there are a total of four mounting pads  608  that are uniformly spaced about the outer perimeter  617  (e.g., each mounting pad  608  is spaced approximately 90° from each adjacent mounting pad  608  about outer perimeter). 
     Referring now to  FIG. 7 , a force sensor  700  that may be the force sensor  100  in  FIG. 1  is shown. The force sensor  700  shown in  FIG. 7  may be similar to the force sensor  200  shown in  FIGS. 2A-2D  and may include a number of the same components described above (however, some of these shared components may not be shown in  FIG. 7  so as to simplify the drawings and the description below). 
     The force sensor  700  includes a mounting frame  702  including multiple mounting pads  704  that are extended outward from opposing sides  706  of an outer perimeter  708  of a mold compound  710 . The mounting pads  704  are coupled to a portion (not shown) via connection portions  709 , wherein the portion (not shown) may be engaged or integrated with a die pad coupled to a semiconductor die (not shown) as described above. The connection portions  709  on each of the opposing sides  706  flare or diverge away from one another moving outward from the opposing sides  706 . Accordingly, mounting frame  702  may transfer (and potentially amplify) forces transferred to mounting pads  704  in multiple directions along a plane including or parallel to the mounting pads  704  during operations. In some examples, the connection portions  709  on a given side  706  of outer perimeter  708  may diverge away from one another at an angle β that may range from 0° to 90°, such as from 20° to 45°. In some examples, the angle β is chosen to provide suitable flexibility to the mounting pads  704  and to facilitate sufficient conformance of the mounting pads  704  for engagement with the member of interest (e.g., shaft  102  in  FIG. 1 ). In some examples, the angle β may be chosen based on the geometrical constraints of the member of interest, and/or to magnify the force transferred through the mounting frame  702 . For instance, in some examples the angle β may be greater than 0° and less than or equal to 90°, such as greater than or equal to 20° and less than or equal to 45°. The independent legs allow for more independent movement and placement of the mounting pads for more efficient mounting to the member of interest. Flaring out may allow differential forces to transfer through the mounting frame in multiple directions. 
     Referring now to  FIG. 8 , a force sensor  800  that may be the force sensor  100  in  FIG. 1  is shown. The force sensor  800  shown in  FIG. 8  may be similar to force sensor  200  shown in  FIGS. 2A-2D  and may include a number of the same components described above (however, some of these shared components may not be shown in  FIG. 8  so as to simplify the drawings and the description below). 
     Force sensor  800  includes a semiconductor die  802  that is mounted to a die pad  804 . The die pad  804  may be directly engaged with a member  806  that may include a structural component of a mechanical system (e.g., a beam, strut, column). The die pad  804  may be secured to the member  806  with an adhesive. During operations forces transferred from the member  806  to the die pad  804  are also transferred to the semiconductor die  802 . The semiconductor die  802  may include a circuit (not shown) that is configured to detect the forces transferred from die pad  804  (e.g., via piezoresistive changes as described above). For the force sensor  800 , the die pad  804  therefore forms a mounting frame that engages with the member  806 , but the die pad  804  does not extend outward past an outer perimeter  810  of a mold compound  812  that covers the semiconductor die  802  and die pad  804 . 
     Referring now to  FIGS. 9A and 9B , force sensors  900  that may be the force sensor  100  in  FIG. 1  are shown according to some examples.  FIGS. 9A and 9B  may be collectively referred to herein as “ FIG. 9 .” The force sensors  900  shown in  FIGS. 9A and 9B  may be similar to the force sensor  200  shown in  FIGS. 2A-2D  and may include a number of the same components described above (however, some of these shared components may not be shown in  FIGS. 9A and 9B  so as to simplify the drawings and the description below). 
     Force sensors  900  shown in  FIGS. 9A and 9B  may include a mounting frame  902  having mounting pads  904  extending outward from an outer perimeter  906  of a mold compound  908 . As was described above for force sensor  200  in  FIGS. 2A-2D , the mounting pads  904  (one of the mounting pads  904  is not visible in  FIGS. 9A and 9B ) are secured to a member  910  of interest which may be a part or component of a mechanical system (e.g., shaft, strut, column, beam, casing), and forces experienced by the member  910  may be transferred to the force sensor  900  via the engagement with mounting pads  904 . 
     Also, the force sensors  900  include conductive terminals  912  that also extend outward from mold compound  908 . The conductive terminals  912  may be coupled to suitable conductive pads or members (not shown) on a printed circuit board (PCB) (or multiple PCBs)  914 . The PCBs  914  may be separated from the outer surface of member  910  to prevent forces experienced by the member  910  from damaging the PCBs  914  or components coupled thereto. In  FIG. 9A , the mounting pads  904  may be engaged with a projection  916  defined along the surface of the member  910 . Accordingly, conductive terminals  912  may be raised above the surface of member  910  to engage with PCBs  914  as shown. In  FIG. 9B , an isolating material  918  is placed between the conductive terminals  912  and the outer surface of the member  910  to prevent electrical shorts between the conductive terminals  912  and the member  910  during operations. 
     Referring now to  FIGS. 10A and 10B , a force sensor  1000  that may be the force sensor  100  in  FIG. 1  is shown according to some examples.  FIGS. 10A and 10B  may be collectively referred to herein as “ FIG. 10 .” The force sensor  1000  shown in  FIGS. 10A and 10B  may be similar to the force sensor  200  shown in  FIGS. 2A-2D  and may include a number of the same components described above (however, some of these shared components may not be shown in  FIGS. 10A and 10B  so as to simplify the drawings and the description below). 
     Force sensor  1000  includes a first semiconductor die  1002  and a second semiconductor die  1004  covered by a mold compound  1006 . The second semiconductor die  1004  may be mounted to a die pad  1008  that may also be covered by the mold compound  1006 . In some examples, the die pad  1008  may be exposed (e.g., partially, wholly) out of the mold compound  1006 . The first semiconductor die  1002  is mounted to a die pad  1010  that extends beyond an outer perimeter  1012  of the mold compound  1006  to form a pair of mounting pads  1014  in the manner described above for sensor  200  (e.g., mounting pads  230 ). Thus, the die pad  1010  and mounting pads  1014  may together define or form a mounting frame  1016  for force sensor  1000  that is similar to mounting frame  232  of force sensor  200  ( FIGS. 2A-2D ). 
     The first semiconductor die  1002  and the second semiconductor die  1004  are electrically coupled to one another via wire bond(s)  1018  and/or any other suitable electrically coupling. During operations mounting pads  1014  of mounting frame  1016  are secured to a member of interest (e.g., shaft  102  in  FIG. 1 ) so forces are transferred through the mounting frame  1016  to the first semiconductor die  1002  as described above. The first semiconductor die  1002  may include a circuit (e.g., circuit  208  shown in  FIGS. 2C and 2D  and described above) that is to detect the transferred forces from mounting frame  1016  in the manner described above (e.g., via piezoresistive changes in the circuit). The first semiconductor die  1002  may output a signal including the detected forces (or a value or values that are indicative of the detected forces) to the second semiconductor die  1004 . The second semiconductor die  1004  may include a circuit that may conduct further signal processing and/or that may communicate the detected forces (or signal indicative thereof) to another device or component. 
     Without being limited to this or any other theory, by providing two semiconductor dies  1002 ,  1004  in which the second semiconductor die  1004  is not directly mounted to the member of interest, the second semiconductor die may be insulated from the forces transferred to the first semiconductor die  1002  via mounting frame  1016  such that damage to the components (e.g., circuit, silicon) of the second semiconductor die  1004  may be prevented or reduced in likelihood. In addition, providing two semiconductor dies (e.g., first semiconductor die  1002  and second semiconductor die  1004 ) may allow more space for circuits thereby increasing the functional capabilities of force sensor  1000 . 
     Still other examples are contemplated that include a combination of features from other examples described above. Specifically, other force sensors contemplated herein may include any combination of the features described above for force sensors  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900 ,  1000  etc. 
     The examples described above include force sensors including mounting frames for mounting the force sensors to a member of interested (e.g., a rotating shaft, a beam). In some examples, the force sensors may include a semiconductor die that is secured to the member via the mounting frame. As described above, by securing the force sensor to the member of interested via a mounting frame, the function and sensitivity of the force sensor may be enhanced. 
     In this description, the term “couple” may cover connections, communications or signal paths that enable a functional relationship consistent with this description. For example, if device A provides a signal to control device B to perform an action, then: (a) in a first example, device A is directly coupled to device B; or (b) in a second example, device A is indirectly coupled to device B through intervening component C if intervening component C does not substantially alter the functional relationship between device A and device B, so device B is controlled by device A via the control signal provided by device A. 
     A device that is “configured to” perform a task or function may be configured (e.g., programmed and/or hardwired) at a time of manufacturing by a manufacturer to perform the function and/or may be configurable (or reconfigurable) by a user after manufacturing to perform the function and/or other additional or alternative functions. The configuring may be through firmware and/or software programming of the device, through a construction and/or layout of hardware components and interconnections of the device, or a combination thereof. 
     A circuit or device that is described herein as including certain components may instead be adapted to be coupled to those components to form the described circuitry or device. For example, a structure described as including one or more semiconductor elements (such as transistors), one or more passive elements (such as resistors, capacitors, and/or inductors), and/or one or more sources (such as voltage and/or current sources) may instead include only the semiconductor elements within a single physical device (e.g., a semiconductor die and/or integrated circuit (IC) package) and may be adapted to be coupled to at least some of the passive elements and/or the sources to form the described structure either at a time of manufacture or after a time of manufacture by an end-user and/or a third-party. 
     While certain components may be described herein as being of a particular process technology, these components may be exchanged for components of other process technologies. 
     Unless otherwise stated, “about,” “approximately,” or “substantially” preceding a value means+/−10 percent of the stated value. Modifications are possible in the described examples, and other examples are possible within the scope of the claims.