Patent Publication Number: US-11662236-B2

Title: Sensor package with ingress protection

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation of U.S. application Ser. No. 16/190,059, entitled “Sensor Package with Ingress Protection,” filed Nov. 13, 2018, which claims priority to U.S. Provisional Application No. 62/586,115, entitled “Sensor Package with Ingress Protection,” filed Nov. 14, 2017, each of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     In a microelectromechanical system (MEMS) sensor a MEMS die includes at least one diaphragm and at least one back plate. The MEMS die is supported by a base or substrate and enclosed by a housing (e.g., a cup or cover with walls). A port may extend through the substrate (for a bottom port device) or through the top of the housing (for a top port device). Sound energy traverses through the port, moves the diaphragm, and creates a changing electrical potential of the back plate, which creates an electrical signal. Sensors are deployed in various types of devices such as personal computers, cellular phones, mobile devices, headsets, and hearing aid devices. 
     SUMMARY 
     In an aspect of the disclosure, a sensor includes a substrate having a first surface and an opposing second surface, the second surface defining an indented region having an indented surface, the substrate defining a bottom port extending between the first surface and the indented surface. The sensor further includes a microelectromechanical system (MEMS) transducer mounted on the first surface of the substrate over the bottom port. The sensor also includes a filtering material disposed on the indented surface and positioned to cover the bottom port, the filtering material structured to prevent ingress of contaminants through the bottom port. The sensor further includes a cover disposed over the first surface of the substrate, the cover defining a back volume enclosing the MEMS transducer and the IC. 
     The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the following drawings and the detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings. 
         FIG.  1    shows a cross-sectional view of first example sensor device according to an embodiment of the present disclosure. 
         FIG.  2    shows a cross-sectional view of a portion of the first example sensor device shown in  FIG.  1   . 
         FIG.  3    shows a cross-sectional view of a portion of another sensor device that incorporates a mesh within the sensor package. 
         FIG.  4    shows a top view of the first example sensor device shown in  FIGS.  1  and  2   . 
         FIG.  5    shows a top view of the other sensor device, a portion of which is shown in  FIG.  3   . 
         FIG.  6    shows a bottom view of the first example sensor device shown in  FIG.  1   . 
         FIGS.  7  and  8    show isometric views of a front surface and a back surface, respectively, of a substrate of the first sensor device shown in  FIG.  1   . 
         FIG.  9    shows a cross-sectional view of a portion of yet another sensor device that incorporates more than one mesh within the sensor package. 
     
    
    
     In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure. 
     DETAILED DESCRIPTION 
     The present disclosure describes devices and techniques for improving the robustness of sensor devices, such as those incorporating microelectromechanical systems (MEMS) transducers. In particular, the devices and techniques described in the present disclosure improve the resistance of a sensor package to ingression of contaminants, such as, for example, solid particles and liquids. In some implementations, the present disclosure may provide for improved resistance to contaminant ingression with little or no impact to the signal-to-noise ratio (SNR) of the sensor device. 
     In one or more embodiments, the sensor package can include a substrate with a bottom port through which sound energy can enter the sensor package and be incident on a MEMS transducer. The bottom port can be covered with a filtering structure or material that is acoustically permeable, but obstructs the passage of contaminants from entering the sensor package. In some such embodiments, the filtering material is a mesh material. In some implementations, the mesh can be disposed on an external or outer surface of the sensor package. For example, the mesh can be disposed within an indented region of an external or outer surface of the sensor package, which allows the mesh to have a relatively large surface area and thereby have a low acoustic impedance. As acoustic impedance can affect the SNR of the sensor device, the low acoustic impedance of the mesh may have substantially no impact on the SNR of the sensor device. The structures disclosed herein can be used to implement sensor devices such as audio sensor devices or microphone devices. The structures disclosed herein can also be used in related sensors, such as pressure sensors, sensors designed to detect non-audible frequencies such as ultrasonic, and multi-functional sensors that include the ability to detect pressure, gas, humidity or temperature. 
     In some embodiments, the bottom port is defined in a substrate of the sensor device. The substrate can include an indented region on a back surface of the substrate and around the bottom port. The mesh can be disposed within the indented region to cover the bottom port. The indented region can have a depth that is greater than a thickness of the mesh. In some embodiments, the indented region can have a depth that is substantially the same as a thickness of the mesh, such that a surface of the mesh is approximately flush with the surface of the substrate. In some embodiments, the sensor device can include a ground ring on the back surface of the substrate that surrounds the indented region and the bottom port. 
     In an aspect of the disclosure a sensor includes a substrate having a first surface and an opposing second surface, the second surface defining an indented region having an indented surface, the substrate defining a bottom port extending between the first surface and the indented surface. The sensor further includes a microelectromechanical system (MEMS) transducer mounted on the first surface of the substrate over the bottom port. The sensor also includes a filtering material disposed on the indented surface covering the bottom port, the filtering material structured to prevent ingress of particles through the bottom port. The sensor additionally includes an integrated circuit (IC) mounted on the first surface of the substrate, and a cover disposed over the first surface of the substrate, the cover defining a back volume enclosing the MEMS transducer and the IC 
       FIG.  1    shows a cross-sectional view of first example sensor device  100  according to an embodiment of the present disclosure. The first example sensor device  100  includes a substrate  110 , a microelectromechanical systems (MEMS) transducer  102 , an integrated circuit (IC)  104 , and a cover  108 . The substrate  110  includes a first surface (“front surface”)  116  and an opposing second surface (“back surface”)  114 . The MEMS transducer  102  and the IC  104  are disposed on the front surface  116  of the substrate  110 . A first set of wires  124  electrically connect the MEMS transducer  102  to the IC  104 , and a second set of wires  126  connect the IC  104  to interconnects (not shown) on the front surface  116  of the substrate  110 . The MEMS transducer  102 , the IC  104 , and the substrate  110  can each include conductive bounding pads to which ends of the wires can be bonded. In some embodiments, wires  124  can be bonded to the appropriate bonding pads using a solder. Optionally, in some embodiments an encapsulating material  106  can at least partially (or in some instances completely) cover the IC  104  and the second set of wires  126 . By covering the IC  104  and the second set of wires  126  within the encapsulating material  106 , an effect of radio frequency signals, generated by the IC  104  and the second set of wires  125 , on the MEMS transducer  102  and other components mounted on the substrate  110  can be reduced. The cover  108  encloses the MEMS transducer  102 , the IC  104 , the first set of wires  124 , and the second set of wires  125 , and defines a back volume of the sensor device  100 . In some implementations, at least a portion of the IC  104  can be embedded into the substrate  110 . For example, the front surface  116  of the substrate  110  can include a cavity, and the IC  104  can be disposed within the cavity. In some implementations, the cavity can be deeper than a height of the IC  104 , such that a top surface of the IC  104  lies below the plane of the front surface  116 . In some other implementations, the depth of the cavity can be such that the top surface of the IC  104  lies above the plane of the front surface  116  of the substrate  110 . 
     The substrate  110  can include, without limitation, a printed circuit board, a semiconductor substrate, or a combination thereof. The substrate  110  can define an indented region  128  on the back surface  114  of the substrate  110 . The indented region  128  can include an indented surface  130  that is offset from the back surface  114 , such that a distance between the indented surface  130  and the front surface  116  is less than a distance between the back surface  114  and the front surface  116 . The substrate  110  also defines a bottom port  132  that extends between the indented surface  130  and the front surface  116 . The bottom port  132  is positioned below the MEMS transducer  102  and provides an acoustic channel between the MEMS transducer  102  and the outside of the sensor device  100 . The bottom port  132  can have a circular, elliptical, or a polygonal (regular or irregular) shape in a plane that is parallel to the front surface  116 . 
     An opening of the bottom port  132  on the indented surface  130  can be covered with a filtering material, such as, for example, a mesh filter  134 . The mesh  134  can be acoustically permeable. That is, the mesh  134  can allow sound energy from outside of the sensor device  100  to enter the bottom port  132  and be incident on the MEMS transducer  102 . The acoustic permeability of the mesh  134  can be high, such that the presence of the mesh  134  does not substantially affect the SNR of the sensor device  100 . In some implementations, the acoustic permeability of the mesh  134  can be selected such that the SNR of the sensor  100  with the mesh  134  is no less than about 90% of the SNR of the sensor  100  without the mesh  134 . Stated another way, the SNR of the sensor  100  with the mesh  134  is substantially similar to the SNR of the sensor  100  without the mesh  134 . The mesh  134  can include a porous material that allows sound to pass through, but prevents contaminants, such as solid particles and liquids, from entering through the bottom port  132 . The solid particles, can include, for example, dust particles and solder flux particles. In some implementations, the mesh  134  can include a metal screen with small openings. In some implementations, the mesh  134  can be configured to provide ingress protection to an extent that is equal to or exceeds the International Electrotechnical Commission (IEC) IP67 rating. 
     In some implementations, the mesh  134  can be formed of a netting, network, or interlace of a material, which can include, without limitation, a metal, a polymer (such as, for example, a polyamide), a composite, or a combination thereof. In some implementations, the mesh  134  can include openings that can range from about 1 micron to about 7 microns in size. In some implementations, the material used to form the mesh  134  can have hydrophobic properties, to prevent liquids from entering through the bottom port  132 . For example, the mesh  134  can include Teflon, or Teflon-like materials to impart hydrophobic properties. In some implementations, a porous membrane can be utilized instead of, or in addition to, the mesh  134 , where the membrane can have pores with sizes that are similar to those discussed above in relation to the mesh  134 . In addition, the membrane can be made of materials similar to those discussed above in relation to the mesh  134 . 
     In some implementations, the mesh  134  can be removably disposed over the bottom port  132 . For example, the mesh  134  can be bonded to the indented surface  130  with an adhesive, such that the adhesive holds the mesh  134  in place over the bottom port  132 , but can also allow the mesh  134  to be pulled and removed from over the bottom port  132  when sufficient force is applied. In some implementations, an epoxy can be used to bond the mesh  134  to the indented surface  130 . In some other implementations, a die-attach can be used to bond the mesh  134  to the indented surface  130 , such that the mesh  134  can be removed. In some implementations, a double sided adhesive film or tape can be used to bond the mesh  134  to the indented surface  130 . The mesh  134  can be placed on the indented surface  130  using a pick-and-place system or a bonder. The adhesive can be applied to the indented surface  130 , to the mesh  134  or both the indented surface  130  and the mesh  134  before the mesh  134  is placed on the indented surface  130 . The mesh  134  can be removable and replaceable, such that once removed the mesh  134  can be replaced with another mesh or filtering material. 
     In some implementations, the mesh  134  can be disposed completely within the indented region  128 . That is, a depth of the indented region  128 , measured as a distance between the back surface  114  and the indented surface  130 , can be equal to or greater than a thickness of the mesh  134 . In some implementations, the depth of the indented region  128  can be greater than a distance between a surface of the mesh  134  facing the back surface  114  and the indented surface  130 . Disposing the mesh  134  completely within the indented region  128  can protect the mesh  134  from damage. In some other implementations, the mesh  134  may be partially disposed within the indented region  128 . In some such implementations, the depth of the indented region  128  can be less than a thickness of the mesh  134 . Alternatively, the depth of the indented region  128  can be less than the distance between a surface of the mesh  134  facing the back surface  114  and the indented surface  130 . In still further implementations, the depth of the indented region  128  can be substantially equal to the thickness of the mesh  134 , such that the back surface  114  and a surface of the mesh  134  are substantially coplanar or flush with one another. 
     The sensor device  100  can include a first ground ring  136  disposed on the back surface  114  of the substrate  110 . In some implementations, the first ground ring  136  can completely surround the indented region  128 . In some other implementations, the first ground ring  136  may partially surround the indented region  128 . In some implementations, the first ground ring  136  can be continuous. Alternatively, the first ground ring  136  can be discontinuous. The first ground ring  136  can include a conductive material such as copper, aluminum, silver, gold, or other conductive materials. In some implementations, the first ground ring  136  can be electrically coupled to a ground terminal of the sensor device  100 . 
     As discussed above, the mesh  134  and the bottom port  132  allow sound energy to be incident on the MEMS transducer  102 . The MEMS transducer  102  can include a diaphragm and a back plate that are disposed in a spaced-apart relationship. Both the diaphragm and the back plate can include conductive materials such that the combination of the diaphragm and the back plate form a variable capacitor, the capacitance of which is based in part on the distance between the diaphragm and the back plate. Acoustic energy incident on the diaphragm can cause the displacement of the diaphragm in relation to the back plate, causing a change in the capacitance of the variable capacitor. The change in the capacitance can be a function of the frequency and the magnitude of the incident acoustic energy. The MEMS transducer  102  can convert this change in capacitance in to an electrical signal. The electrical signal can be provided to the IC  104 , which processes the electrical signal to generate a sensor signal. The IC  104  can include analog and digital circuity for carrying out processing such as, without limitation, amplification, filtering, analog-to-digital conversion, digital-to-digital conversion, and level shifting. 
     In some implementations, the sensor device  100  can be utilized as a microphone device, where the sensor  100  generates electrical signals corresponding to incident audible sound signals. In some implementations, the sensor  100  also can be utilized as a pressure sensor, where the sensor  100  generates electrical signals responsive to pressure changes. In some implementations, the sensor  100  also can be utilized as an acoustic sensor, where the acoustic sensor  100  generates electrical signals responsive to incident acoustic energy of any level and any frequency ranges, such as ultrasonic, subsonic, etc. 
       FIG.  2    shows a cross-sectional view of a portion of the first example sensor device  100  shown in  FIG.  1   . In particular,  FIG.  2    shows the MEMS transducer  102  disposed on the front surface  116  of the substrate  110 , and the mesh  134  disposed on the indented surface  130  and covering the bottom port  132 . The MEMS transducer  102  is coupled to the front surface  116  with a die attach  140 . The die attach  140  can include an adhesive, a solder, an epoxy, or some other material that can bond the MEMS transducer  102  to the front surface  116 . The mesh  134  is bonded to the indented surface  130  with a bonding material  142 , which can include a die attach, a solder, an adhesive, an epoxy, or some other material that can bond the mesh  134  to the indented surface  130 . The placement of the mesh  134  within a recess  128  on a back surface  114  of the substrate  110  of the sensor device  100 , as opposed to between the substrate  110  and the MEMS transducer  102 , can improve the acoustic permittivity of the mesh  134 . The improvement in the acoustic permittivity can be a result, in part, of a larger effective surface area of the mesh  134  and, in part, on a larger cross-sectional area of the bottom port, in comparison to those associated in an arrangement where the mesh is positioned between the MEMS transducer and the substrate. The effective surface area can refer to an area of a portion of the mesh  134  that is exposed and allows flow of acoustic energy therethrough. For example, Wm 1  indicates a width of the area of the portion of the mesh  134  that is exposed, i.e., not covered by the bonding material  142 , and allows the flow of acoustic energy. Also, Wp 1  indicates a width of the bottom port  132 . In some implementations, the width Wm 1  of the effective area of the mesh  134  is greater than the width Wp 1  of the bottom port  132 . In some implementations, the effective surface area of the mesh  134  can be greater than the cross-sectional area of the bottom port  132 . 
     In some implementations, the cross-sectional area (within a plane parallel to the front surface  116  or the indented surface  130 ) of the bottom port  132  can have any shape including, without limitation, circular, elliptical, and polygonal (regular or irregular). In some implementations, a dimension of the cross-sectional area of the bottom port  132  can be about 325 microns to about 1100 microns. The dimension can include, without limitation, a diameter, a major axis, a longitudinal axis, and a diagonal. In some implementations, the substrate  110  can define more than one bottom port or opening. For example, the substrate  110  can define two bottom ports or openings extending between the front surface  116  and the indented surface  130  and positioned below the MEMS transducer  102 . The cross-sectional areas of each of the more than one bottom port or opening can be equal or unequal, and can have any of the cross-sectional area shapes discussed above in relation to the bottom port  134 . In some implementations, the surface area of the of a portion of the mesh  134  that allows flow of acoustic energy therethrough is greater than a cross-sectional area of the bottom port  134 . 
       FIG.  3    shows a cross-sectional view of a portion of a traditional sensor device  300  that incorporates a mesh disposed between the substrate and the MEMS die, and is reproduced here to help illustrate the features and benefits of the example sensor device  100  shown in  FIG.  2   . In particular, the sensor device  300  includes a substrate  310 , a MEMS transducer  302 , and a mesh  334 . The substrate  310  defines a bottom port  332  that extends between a front surface  316  and a back surface  314  of the substrate  310 . The mesh  334  is disposed on the front surface  316  by a bonding material  342 . The MEMS transducer  302  is disposed on the mesh  334  by a bonding material  340 . A width of the MEMS transducer  302  is typically fixed. During manufacturing sensor device  300  shown in  FIG.  3   , an opening in each layer below the MEMS transducer  302  has a reduced width to provide adequate structural support to the layers above. For example, the width of the opening in the bonding material  342 , between the mesh  334  and the substrate  310 , is smaller than the width of the opening in the bonding material  340  between the MEMS transducer  302  and the mesh  334 . Further, a width Wp 2  of the bottom port  332  in the substrate  310  is smaller than the width of the opening in the bonding material  342  to provide adequate structural support to the bonding material  342 . Thus, the width Wp 2  of the bottom port  332  is limited by the number of layers between the substrate  310  and the MEMS transducer  302 . In addition, a width Wm 2  of the effective area of the mesh  334  is limited by the width of the opening in the bonding material  342 . 
     In contrast, referring to  FIG.  2   , only the die attach layer  140  is disposed between the MEMS transducer  102  and the substrate  110 . Thus, the width Wp 1  of the bottom port  132  is relatively larger than the width Wp 2  of the bottom port  332  shown in  FIG.  3   . In some implementations, the width Wp 1  can be about 0.325 mm to about 1.1 mm, and the width Wp 2  can be about 0.25 mm to about 0.65 mm. In addition, as the mesh  134  in  FIG.  2    is disposed on the indented surface  130 , the opening in the bonding material  142  can be made as large as possible while providing adequate support to the mesh  134 . The resulting effective area, the width Wm 1  of which is indicated in  FIG.  2   , is substantially larger than that (Wm 2 ) of the mesh  334  shown in  FIG.  3   . In some implementations, the width Wm 1  can be about 0.3 mm to about 1.15 mm, and the width Wm 2  can be about 0.65 mm to about 0.85 mm. Thus, by disposing the mesh  134  below the substrate  110 , instead of between the MEMS transducer and the substrate, the width of the bottom port  132  and the effective area of the mesh  134  can be increased. Increasing the width of the bottom port and increasing the effective area of the mesh  134  can, in turn, improve the acoustic permittivity of the mesh  134  and the bottom port  132 , thereby reducing the impact on the SNR of the sensor device  100 . 
     In addition, disposing the mesh  134  within the recess  128  formed on the back surface  114  of the substrate  110 , as shown in  FIG.  2   , reduces the complexity and cost of manufacturing the sensor device  100  as compared to that of the sensor device  300  shown in  FIG.  3   . As mentioned above, the layers in the sensor device  300  disposed below the MEMS transducer  302  have respective openings with gradually increasing widths starting from the substrate  310  to the bonding material  340 . To achieve the widest possible bottom port  332 , each layer may be deposited and patterned with high accuracy and precision. This desire for high accuracy and precision can increase the cost of manufacturing of the sensor device  300 . On the other hand, the sensor device  100  shown in  FIG.  2    has only one die attach  140  layer disposed between the substrate  110  and the MEMS transducer  102 . This allows the manufacturing process to have relaxed accuracy and precision to achieve a bottom port  132  with the same or more width than the bottom port  332  shown in  FIG.  3   . Thus, the cost of manufacturing is also reduced. 
       FIG.  4    shows a top view of the first example sensor device  100  shown in  FIGS.  1  and  2   .  FIG.  5    shows a top view of a traditional sensor device, a portion of which is shown in  FIG.  3   .  FIGS.  4  and  5    show top views of the sensors with their respective covers removed. In particular, the sensor device  100  shown in  FIG.  4    includes a mesh (not shown), where the substrate  110  is disposed between the MEMS transducer  102  and the mesh.  FIG.  5   , in contrast, has the mesh  334  disposed between the MEMS transducer  302  and the substrate  310 . In  FIG.  4   , the width of the bottom port  132  is relatively larger than that of the bottom port  332  shown in  FIG.  5   . In addition, the sensor device  100  shown in  FIG.  4    includes a second ground ring  146  that can be used for bonding the cover  108  to the substrate  110 . The placement of the mesh on the back surface of the substrate  110  in  FIG.  4    provides additional area that can be used to accommodate a larger MEMS transducer  102 , or a larger bottom port  132 , compared to the MEMS transducer  302  and the bottom port  332 , respectively, of the sensor device  300  shown in  FIG.  5   . 
       FIG.  6    shows a bottom view of the first example sensor device  100  shown in  FIG.  1   . The sensor device  100  includes the first ground ring  136  surrounding the mesh  134  and the bottom port  132 . The first ground ring  136  can be disposed over the back surface  114  of the substrate  110  (also as shown in  FIG.  1   ). While  FIG.  6    shows the first ground ring  136  completely surrounding the mesh  134  and the bottom port  132  within the indented region  128 , in some embodiments, the first ground ring may only partially surround the mesh  134  and the bottom port  132 . The first ground ring  136  can provide a surface to couple with a port or channel of an end device in which the sensor device  100  is installed. For example, the sensor device  100  can be installed in a phone. The first ground ring  136  can be shaped to match a shape of a port or channel of the phone housing that directs acoustic signals from outside of the phone package into the sensor device  100 . The first ground ring  136  can provide a bonding surface on which the port or channel of the phone housing can be bonded. In some implementations, the first ground ring  136  can include a conductive material such as, for example, copper, aluminum, silver and gold. In some implementations, a perimeter of the first ground ring  136  can have a shape that is similar to the shape of the bottom port  132 . For example, as shown in  FIG.  6   , both the perimeter of the first ground ring  136  and the perimeter of bottom port  132  are rectangular. Alternatively, the shape of the perimeter of the ground ring  136  can be different from the shape of the perimeter of the bottom port. For example, the shape of the perimeter of the first ground ring  136  can be rectangular, while that of the bottom port  132  can be circular. In some implementations, the shape of the perimeter of the first ground ring  136  can be circular, elliptical, rectangular, square, or polygonal (regular or irregular). 
     The sensor device  100  also includes electrical contacts  150  disposed on the back surface  114 . The electrical contacts  150  allow electrical connectivity to one or more terminals of the sensor device  100 . For example, the electrical contacts  150  can represent terminals such as, without limitation, a clock input terminal, a data output terminal, a left/right selection input terminal, and a power supply terminal. When installed in an application, the electrical contacts  150  can be electrically connected to other electronic circuitry in the application. 
       FIGS.  7  and  8    show isometric views of a front surface and a back surface, respectively, of a substrate of the first sensor device  100  shown in  FIG.  1   .  FIG.  7    shows a bottom port  132  formed in the substrate  110 . While not shown, a MEMS transducer, such as the MEMS transducer  102  shown in  FIG.  1   , can be disposed on the front surface  116  over the bottom port  132 . The substrate  110  can be a multi-layer printed circuit board, where one or more layers can include interconnects for carrying electrical signals. The front surface  116  can define an opening  152  exposing underlying interconnects  154 . During the manufacturing process, one or more bonding wires can be connected between the interconnects  154  and an IC or a MEMS transducer disposed on the front surface  116 . The substrate  110  also includes the second ground ring  146  to which a cover, such as the cover  108  shown in  FIG.  1   , can be bonded. 
       FIG.  8    shows the back surface  114  of the substrate  110 . The substrate  110  includes the indented region having an indented surface  130 . The bottom port  132  extends between the indented surface  130  and the front surface  116  (shown in  FIG.  7   ). While not shown in  FIG.  8   , a mesh, such as the mesh  134  shown in  FIG.  1   , can be disposed on the indented surface  130  covering the bottom port  132 . The substrate  110  includes the first ground ring  136  that surrounds the indented region and the bottom port  132 . The substrate  110  additionally includes four electrical contacts  150  that provide connectivity to one or more interconnects in the substrate  110 . 
       FIG.  9    shows a cross-sectional view of a portion of another sensor device  900  that incorporates more than one mesh. In particular, the sensor device  900  shown in  FIG.  9    incorporates a first mesh disposed between the substrate and the MEMS transducer and a second mesh disposed on an indented surface of the substrate and covering the bottom port. For example,  FIG.  9    shows that the first mesh  334  is disposed between the front surface  316  of the substrate  310  and the MEMS transducer  302 , and a second mesh  134  bonded to the indented surface  130  and covering the bottom port  132 . The first mesh  334  can be similar to the mesh  334  discussed above in relation to  FIG.  3   , and the second mesh  134  can be similar to the mesh  134  discussed above in relation to  FIG.  2   . For example, the first mesh  334  can have a width Wm 2  of an effective area similar to the width Wm 2  of the effective area of the mesh  334  shown in  FIG.  3   . The width Wm 1  of an effective area of the second mesh  134  can be similar to the width Wm 1  of the effective area of the mesh  134  shown in  FIG.  2   . The combination of the first mesh  334  and the second mesh  134  provides additional ingress protection to the MEMS transducer  302 . For example, the ingress protection provided by the sensor device  900  can be greater than the ingress protection provided by the sensor device  200  or the sensor device  300  alone. 
     Each of the sensor devices discussed above can provide a degree of ingress protection that meets the ISO 22810 standard. In some examples, the sensor devices can provide water ingress protection up to 3 atmosphere pressure (or at a depth of 30 meters) or up to 5 atmosphere pressure (or a depth of 50 meters). 
     The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are illustrative, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected,” or “operably coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable,” to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components. 
     With respect to the use of plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. 
     It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). 
     It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). 
     Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” Further, unless otherwise noted, the use of the words “approximate,” “about,” “around,” “substantially,” etc., mean plus or minus ten percent. 
     The foregoing description of illustrative embodiments has been presented for purposes of illustration and of description. It is not intended to be exhaustive or limiting with respect to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosed embodiments. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.