WO2019133644A1

WO2019133644A1 - Back volume free sensor package

Info

Publication number: WO2019133644A1
Application number: PCT/US2018/067561
Authority: WO
Inventors: John James Lorimer BEARD; Yu Du
Original assignee: Knowles Electronics, Llc
Priority date: 2017-12-28
Filing date: 2018-12-26
Publication date: 2019-07-04
Also published as: CN212572960U

Abstract

A sensor device includes a base having a front surface and an opposing back surface. The base defines a bottom port extending between the front surface and the back surface. The sensor further includes a microelectromechanical systems (MEMS) transducer disposed over the base over the bottom port and an integrated circuit (IC) disposed over the base. The sensor also includes an acoustically transparent cover disposed on the base covering the MEMS transducer and the IC. The acoustically transparent cover is configured to provide high acoustic permittivity.

Description

BACK VOLUME FREE SENSOR PACKAGE

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to ET.S. Provisional Patent Application No. 62/611,235, filed December 28, 2017, the contents of which are incorporated herein by reference in their entirety.

FIELD OF THE DISCLOSURE

[0002] The present disclosure relates generally to acoustic sensor devices and more particularly to acoustic sensor devices with high signal-to-noise ratios.

BACKGROUND

[0003] 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). Acoustic 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

[0004] Various embodiments disclosed herein are related to a sensor. In some

embodiments, the sensor includes a base having a first surface and an opposing second surface, the base defining a bottom port extending between the first surface and the second surface. The sensor further includes a microelectromechanical system (MEMS) transducer disposed on the base over the bottom port. The sensor also includes an integrated circuit (IC) disposed on the base, and an acoustically transparent cover covering the MEMS transducer and the IC.

[0005] In some embodiments, the sensor further includes a conductive coating disposed on the acoustically transparent cover. In some embodiments, the conductive coating has a thickness of about 10 pm to about 100 pm. In some embodiments, the sensor further includes a ground interconnect disposed on the first surface, wherein the conductive coating is electrically connected to the ground interconnect. In some embodiments, the specific acoustic impedance of the acoustically transparent cover is less than 10,000 RaylMKS. In some embodiments, the acoustically transparent cover includes a mesh. In some embodiments, the mesh includes an interlaced network of at least one of a metal, a polymer, or a composite. In some embodiments, the first surface defines a cavity, wherein the IC is at least partially disposed within the cavity. In some embodiments, the IC is stacked between the base and the MEMS transducer, and wherein the IC defines an opening aligned with the bottom port. In some embodiments, the base defines a cavity, the first surface forming a bottom of the cavity, wherein the IC is stacked between the first surface and the MEMS transducer, and wherein the IC defines an opening aligned with the bottom port.

[0006] Various embodiments disclosed herein are related to a microphone. The microphone includes a base having a first surface and an opposing second surface, the base defining a bottom port extending between the first surface and the second surface. The microphone further includes a microelectromechanical system (MEMS) acoustic transducer disposed on the base over the bottom port and configured to generate an electrical signal responsive to an acoustic signal. The microphone also includes an integrated circuit (IC) disposed on the base. The microphone further includes an acoustically transparent cover covering the MEMS acoustic transducer and the IC, the acoustically transparent cover structured to transmit the acoustic signal between a volume enclosed by the acoustically transparent cover and a volume outside of the microphone.

[0007] In some embodiments, the microphone further includes a conductive coating disposed on the acoustically transparent cover. In some embodiments, the conductive coating has a thickness of about 10 pm to about 100 pm. In some embodiments, the microphone further includes a ground interconnect disposed on the first surface, wherein the conductive coating is electrically connected to the ground interconnect. In some embodiments, the specific acoustic impedance of the acoustically transparent cover is less than 10,000 RaylMKS. In some embodiments, the acoustically transparent cover includes a mesh. In some embodiments, the mesh includes an interlaced network of at least one of a metal, a polymer, or a composite. In some embodiments, the first surface defines a cavity, wherein the IC is at least partially disposed within the cavity. In some embodiments, the IC is stacked between the base and the MEMS acoustic transducer, and wherein the IC defines an opening aligned with the bottom port.

[0008] Various embodiments disclosed herein are related to an electronic device. The electronic device includes an airtight enclosure having an opening, the airtight enclosure defining an enclosed volume. The electronic device further includes a substrate disposed in the enclosed volume. The electronic device also includes a sensor disposed on the substrate. The sensor includes a base having a first surface and a second surface, the base defining a bottom port extending between the first surface and the second surface, the bottom port positioned to align with the opening in the airtight enclosure. The sensor further includes a microelectromechanical system (MEMS) transducer disposed on the base over the bottom port, the MEMS transducer separating the enclosed volume from the bottom port and the opening in the airtight enclosure. The sensor also includes an integrated circuit (IC) disposed on the base. The sensor further includes an acoustically transparent cover covering the MEMS transducer and the IC.

[0009] In some embodiments, the electronic device further includes a conductive coating disposed over the acoustically transparent cover. In some embodiments, the electronic device further includes a ground interconnect disposed on the first surface, wherein the conductive coating is electrically connected to the ground interconnect. In some embodiments, the specific acoustic impedance of the acoustically transparent cover is less than 10,000 RaylMKS. In some embodiments, the acoustically transparent cover includes a mesh.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] 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.

[0011] Figure 1 shows a cross-sectional view of first example sensor device, according to an embodiment of the present disclosure.

[0012] Figure 2 shows a cross-sectional view of an electronic device including a sensor device, according to an embodiment of the present disclosure.

[0013] Figure 3 shows a cross-sectional view of a second example sensor device, according to an embodiment of the present disclosure.

[0014] Figure 4 shows a cross-sectional view of a third example sensor device, according to an embodiment of the present disclosure.

[0015] Figure 5 shows a cross-sectional view of a fourth example sensor device, according to an embodiment of the present disclosure.

[0016] Figure 6 shows a cross-sectional view of a fifth example sensor device, according to an embodiment of the present disclosure.

[0017] Figure 7 shows an isometric view of a cut-out of a sixth example sensor device, according to an embodiment of the present disclosure.

[0018] Figure 8 depicts a graph showing a relationship between acoustic self-noise and a back volume for an acoustic transducer, according to an embodiment of the present disclosure.

[0019] 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

[0020] The present disclosure describes devices and techniques for providing sensor packages for sensor devices that are free from a back volume. Sensor packages of the type discussed in the present disclosure typically have a front volume and a back volume. The front volume can generally be defined as a volume between an input port and a transducer of the sensor package, and the back volume can generally be defined as a volume on an opposite side of the transducer from the input port (e.g., typically a volume between the transducer and a cover of the sensor package). The SNR of the sensor is a function, in part, of the magnitude or size of the back volume. For example, the SNR of the sensor can be proportional to the magnitude or size of the back volume, and increasing the size of the back volume generally results in an increase in the SNR of the sensor. For example, Figure 8 shows a plot 800 of a magnitude of an acoustic self-noise of a sensor device for each of several back volume sizes over a frequency range. As shown in Figure 8, the magnitude of the acoustic self-noise associated with the sensor device reduces with an increase in a size of the back volume of the sensor device within an example frequency range of about 100 Hz to about 5 kHz.

Additionally, while not shown in Figure 8, a sensitivity of the sensor device increases with an increase in the magnitude or size of the back volume. The SNR of the sensor device is a function of the acoustic self-noise, which can represent an electrical signal generated by the sensor when no input present (e.g., when no sound input is present). The SNR is also an inverse function of the sensitivity of the sensor device. Thus, a reduction in the acoustic self- noise and an increase in the sensitivity of the sensor with an increase in the size or magnitude of the back volume, also represents a reduction in the SNR of the sensor with a corresponding increase in the size or magnitude of the back volume.

[0021] In various implementations of the present disclosure, the sensor packages are devoid of an air-tight cover or a can used in traditional sensor devices. Instead, the sensor packages include an acoustically transparent cover for covering a transducer and circuitry of the sensor device, where the acoustically transparent cover can be substantially transparent to acoustic energy. The back volume can instead be provided by a device enclosure within which the sensor device package is deployed. This allows for a relatively smaller sensor package without adversely impacting, and in some instances improving, a signal-to-noise ratio of the sensor devices.

[0022] In one or more embodiments, the sensor device can include a base with a bottom port through which sound energy can enter the sensor device and be incident on a

microelectromechanical systems (MEMS) transducer. The sensor device can also include circuitry, such as one or more integrated circuits, disposed on the base. The acoustically transparent cover covers and provides protection to the MEMS transducer and the circuitry. The acoustically transparent cover can be substantially transparent to acoustic energy. That is, the acoustically transparent cover can have low acoustic impedance to acoustic energy incident on its surface. The acoustically transparent cover can also have a metallic coating or layer that is electrically connected to a ground plane at the base to provide electrical shielding of the MEMS transducer.

[0023] In one or more embodiments, the MEMS transducer and the circuitry can be coupled to the base using flip-chip techniques. This can eliminate the need for bonding wires for establishing electrical connections between the MEMS transducer, the circuitry, and the base. In one or more embodiments, the circuitry can be partially or completely embedded into the base. In one or more embodiments, the MEMS transducer and the circuitry can be stacked over the base, further reducing the footprint of the sensor device. The acoustic port can include openings in the base as well as the circuitry, to allow acoustic energy to be incident on the MEMS transducer. In one or more embodiments, the MEMS transducer and the circuitry can not only be stacked, but also be partially or completely embedded in the base.

[0024] Figure 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 base 110, a microelectromechanical systems (MEMS) transducer 102, an integrated circuit (IC) 104, and an acoustically transparent cover 108. The base 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 base 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 base 110. The MEMS transducer 102, the IC 104, and the base 110 can each include conductive bounding pads to which ends of the wires can be bonded. In one or more embodiments, first set of wires 124 and the second set of wires 126 can be bonded to the appropriate bonding pads using a solder. The acoustically transparent cover 108 encloses the MEMS transducer 102, the IC 104, the first set of wires 124, and the second set of wires 125. ETnlike traditional sensor devices, which include a can or cover that provides an airtight or hermetically sealed enclosure, the acoustically transparent cover 108 is substantially transparent to acoustic energy.

[0025] The base 110 can include, without limitation, a printed circuit board, a

semiconductor substrate, or a combination thereof. The base 110 defines a bottom port 132 that extends between the back surface 114 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. The front surface 116 also can include a conducive ground plane or interconnect that can form an electrical connection with the acoustically transparent cover 108. In particular, the ground plane or interconnect can form an electrical connection with a conductive coating or layer 112 on the acoustically transparent cover 108. The ground plane in combination with the conductive coating or layer 112 on the acoustically transparent cover 108 can form an electromagnetic shield around the MEMS transducer 102, the IC 104, the first set of wires 124, the second set of wires 126, and any other electrical components enclosed by the acoustically transparent cover 108. In one or more embodiments, the electromagnetic shield can provide shielding from radio frequency signals.

[0026] The sensor device 100 can have a height Hi defined as a distance between the back surface 114 of the base 110 and a farthest extent of the acoustically transparent cover 108. In one or more embodiments, the height Hi can be about 0.4 mm to about 0.8 mm. In one or more embodiments, the height Hi can be less than about 0.6 mm. [0027] In one or more embodiments, the acoustically transparent cover 108 can allow sound energy to pass through without significant attenuation. In one or more embodiments, the acoustic permittivity of the acoustically transparent cover 108 can be high, such that the specific acoustic impedance of the acoustically transparent cover 108 is less than 10,000 RaylMKS (N s m ³). For the purposes of the present disclosure, a material may be considered acoustically transparent and allow sound energy to pass without significant attenuation if the specific acoustic impedance of the acoustically transparent cover 108 is less than 10,000 RaylMKS (N s m ³).

[0028] In one or more embodiments, the acoustically transparent cover 108 can include a mesh that allows sound to pass through, but prevents contaminants, such as solid particles and liquids, from passing through. The solid particles, can include, for example, dust particles and solder flux particles. In some implementations, the mesh can include a metal screen with small openings. In some implementations, the mesh 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 can include openings of diameters that can range from about 3 micron to about 30 micron in size. In one or more embodiments, the material used to form the mesh can have hydrophobic properties, to prevent liquids from passing through. For example, the mesh can include Teflon, or Teflon-like materials to impart hydrophobic properties. In one or more embodiments, a porous membrane can be utilized instead of, or in addition to, the mesh, where the membrane can have pores with sizes that are similar to those discussed above in relation to the mesh. In addition, the membrane can be made of materials similar to those discussed above in relation to the mesh. The acoustically transparent cover 108 can be attached to the base 110 using a lamination process that can conform the transparent cover 108 to the geometry of the MEMS transducer 102 and the IC 104. In one or more

embodiments, the acoustically transparent cover 108 can be attached to the front surface 116 of the base 110 by an adhesive or a bonding material, such as glue, solder, epoxy, and the like. In one or more embodiments, the thickness of the acoustically transparent cover 108 can be about 20 pm to about 200 pm. [0029] In one or more embodiments, where the acoustically transparent cover 108 is formed of non-conductive materials, the acoustically transparent cover 108 can include the conductive coating or layer 112 to enhance radio frequency (RF) protection of the sensor device. The conductive coating or layer 112 can include conductive materials such as, for example, copper, aluminum, nickel, silver, gold, and other metals. In some instances where the acoustically transparent cover 108 is formed using conductive materials, the conductive coating or layer 112 may not be needed. However, in some such instances the conductive coating or layer 112 may still be included to improve conductivity and RF shielding provided by the acoustically transparent cover 108. In some instances, RF signals in the environment can interfere with the MEMS 102 and the IC 104. In particular, the RF signals may couple with one or more conductive elements in the MEMS 102 and the IC 104 to generate a noise signal that can get added to the electrical signals generated by the MEMS 102 and the IC 104. The conductive coating or layer 112 on the acoustically transparent cover 108, in combination with the ground plane or interconnect on the base 110, can reduce the magnitude of the RF signals incident on the MEMS 102 and the IC 104, thereby reducing the magnitude of the corresponding noise signal added to the electrical signals generated by the MEMS 102 and the IC 104. This reduction in the magnitude of the noise signal can in turn improve the SNR. of the sensor device 100. In all instances, the addition of the conductive coating or layer 112 should not substantially change the acoustic permittivity of the acoustically transparent cover 108. The conductive coating or layer 112 can be provided as a separate metallic mesh laminated on top of the acoustically transparent cover 108 or directly deposited on top of the acoustically transparent cover 108 using processes like sputtering and galvanic plating. In one or more embodiments, the thickness of the conductive coating or layer 112 can be about 10 pm to about 100 pm.

[0030] As discussed above, the bottom port 132 allows sound energy to be incident on the MEMS transducer 102. The MEMS transducer 102 can include a diaphragm 134 and a back plate 136 that are disposed in a spaced-apart relationship. Both the diaphragm 134 and the back plate 136 can include conductive materials such that the combination of the diaphragm 134 and the back plate 136 form a variable capacitor, the capacitance of which is based in part on the distance between the diaphragm 134 and the back plate 136. Acoustic energy incident on the diaphragm 134 can cause the displacement of the diaphragm 134 in relation to the back plate 136, 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 into 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.

[0031] In some implementations, the sensor device 100 can be utilized as a microphone device, where the sensor device 100 generates electrical signals corresponding to incident audible sound signals. In some implementations, the sensor device 100 also can be utilized as a pressure sensor, where the sensor device 100 generates electrical signals responsive to pressure changes. In some implementations, the sensor device 100 also can be utilized as an acoustic sensor, where the acoustic sensor generates electrical signals responsive to incident acoustic energy of any level and any frequency ranges, such as ultrasonic, subsonic, etc.

[0032] Figure 2 shows a cross-sectional view of an electronic device 200 including a sensor 214. In particular, the electronic device 200 can include any electronic device that provides an airtight enclosure 202. For example, the electronic device 200 can be, without limitation, a consumer device such as a smartphone, a tablet, a computer, a smart watch, a microphone, etc.; or measuring devices such as an electronic barometer, a sound meter, etc. The electronic device 200 can include an enclosure 202 that covers and protects various components of the electronic device 200. The enclosure can include a first portion 204 that is attached to a second portion 206. The first portion 204 and the second portion 206 can be formed using one or more materials such as plastic, metal, a composite, polymer, and the like. The first portion 204 and the second portion 206 are sealed with a seal 208 to form an airtight enclosed volume 216. The seal 208 can include one or more of an adhesive, a gasket, an epoxy, which can be used in combination to form an airtight enclosure 202. In one or more embodiments, the enclosure 202 can be configured to provide a sealed enclosed volume 216 to an extent that is equal to or exceeds the International Electrotechnical Commission (IEC) IP67 rating. The enclosure 202 can enclose various components such as a display 218, a substrate or a printed circuit board 210, various electronic components 212 and a sensor 214. The sensor 214 can be implemented using, for example, the first example sensor device 100 discussed above in relation to Figure 1. The enclosure 202 can include a port 220 positioned to allow incident pressure changes to be communicated to a diaphragm of the sensor 214 (such as, for example, the diaphragm 134 of the sensor device 100 shown in Figure 1). The port 220 can be formed by aligned openings in the second portion 206 and the substrate 210. The sensor 214 can be positioned on the substrate 210 over the port 220 such that the sensor seals the port 220 and separates or isolates the port 220 from the enclosed volume 216. In particular, the diaphragm of the sensor 214 separates or isolates the sealed enclosed volume 216 (which serves as a back volume) from the port 220, which is open to the external environment. This allows the enclosed volume 216 to remain airtight, while at the same time allowing the diaphragm of the sensor 214 to respond to changes in pressure communicated through the port 220

[0033] The sensor 214, similar to the sensor device 100, does not include an airtight cover or can. Instead, the sensor 214 includes an acoustically transparent cover, such as the acoustically transparent cover 108 shown in Figure 1. An airtight back volume for the sensor 214 is instead provided by the enclosed volume 216 of the electronic device 200. The presence of the enclosed volume 216 within the electronic device 200 alleviates the need for an airtight cover or can that solely covers the components of the sensor 214. The enclosed volume 216 serves as a back volume for the MEMS transducer of the sensor 214. By not having an airtight cover or can over the sensor 214, the size of the sensor 214 can be reduced. In particular, the height of the sensor 214 can be relatively smaller than that of sensors that employ an airtight cover or can. As a result, the sensor 214 can satisfy ever decreasing profile specifications for sensors used in electronic devices.

[0034] Furthermore, using the enclosed volume 216 of the electronic device 200 as the back volume for the sensor 214 can improve the SNR of the sensor 214 in comparison to the SNR of sensors that include an airtight cover or can. The SNR of the sensor 214 is a function, in part, of the magnitude or size of the back volume. For example, the SNR of the sensor 214 can be proportional to the magnitude or size of the back volume. That is, increasing the magnitude or size of the back volume can desirably result in an increase in the SNR of the sensor 214 (for example, as discussed above in relation to Figure 8). In one or more embodiments, the enclosed volume 216 of the electronic device 200 can provide a relatively larger back volume than that provided by an airtight cover or can of traditional sensor devices. Thus, the SNR of the sensor 214 that utilizes the enclosed volume 216 of the electronic device 200 can have an SNR that is greater than a traditional sensor device using an airtight cover or can to provide a back volume.

[0035] Figure 3 shows a cross-sectional view of a second example sensor device 300. To the extent that certain components of the second example sensor device 300 are similar to those of the first example sensor device 100 shown in Figure 1, such components are labeled with like reference numbers. The second example sensor device 300 does not include the first set of wires 124 and the second set of wires 126 included in the first example sensor device 100 shown in Figure 1. Instead, the second example sensor device 300 forms electrical connections between the MEMS transducer 102, the IC 104, and the base 110 using interconnects (not shown) disposed on the front surface 116 of the substrate. In particular, interconnects on the MEMS transducer 102 and on the IC 104 are soldered (using solder 302) to the interconnects on the front surface 116 of the base 110. The interconnects on the front surface 116 of the base 110 can be structured to provide the desired electrical connections between the MEMS transducer 102, the IC 104, the base 110, and any other components of the second example sensor device 300. The interconnects on the base 110 can alleviate the need for bonding wires, such as the first and second set of bonding wires 124 and 126 shown in Figure 1.

[0036] Alleviating the need for bonding wires can allow further reduction in the size of the sensor package. For example, the height Hi of the first example sensor device 100 shown in Figure 1 accounted for a certain amount of clearance between the first set of bonding wires 124, the second set of bonding wires 126 and the acoustically transparent cover 108. This clearance is needed to avoid an electrical contact between the first and second set of bonding wires 124 and 126 and the conductive acoustically transparent cover 108. In the second example sensor device 300, because there are no bonding wires, there is no need for the clearance between the acoustically transparent cover 108 and the underlying components. Therefore, the acoustically transparent cover 108 can be positioned relatively closer to the MEMS transducer 102 and the IC 104. In one or more embodiments, the acoustically transparent cover 108 can conform to the exposed surfaces of the MEMS transducer 102 and the IC 104. The resulting height H₂ of the second example sensor device 300 can be less than the height Hi of the first example sensor device 100. In one or more embodiments, the height H₂ can be about 0.3 mm to about 0.6 mm.

[0037] The second example sensor device 300 can be used to implement the sensor 214 of the electronic device 200 shown in Figure 2. The reduction in the size of the second example sensor device 300 relative to the first example sensor device 100 can free up valuable space within the electronic device 200, which space can be utilized to include additional

components within the electronic device 200, allow a reduction in overall size of the electronic device 200, or allow a larger enclosed volume 216 (and therefore a larger back volume) in the electronic device 200.

[0038] Figure 4 shows a cross-sectional view of a third example sensor device 400. To the extent that certain components of the third example sensor device 400 are similar to those of the second example sensor device 300 shown in Figure 3, such components are labeled with like reference numbers. The third example sensor device 400 shown in Figure 4 is different from the second example sensor device 300 shown in Figure 3 in that a base 410 of the third example sensor device 400 defines a cavity 418 in the front surface 416. The cavity 418 is positioned between the front surface 416 and the back surface 414 of the base 410. The IC 104 is at least partially embedded into the cavity4l8. In one or more embodiments, a depth of the cavity 418 can be equal to or greater than a thickness of the IC 104. In one or more embodiments, the depth of the cavity 418 can be less than the thickness of the IC 104.

Including the IC 104 into the cavity 418 can result in the third example sensor device 400 having a size that is relatively smaller than that of the first and the second example sensor devices 100 and 300 shown in Figures 1 and 3. In one or more embodiments, the third example sensor device 400 can be used to implement the sensor 214 of the electronic device 200 shown in Figure 2. The smaller size of the third example sensor device 400 can free up valuable space within the electronic device 200, which space can be utilized to include additional components within the electronic device 200, allow a reduction in overall size of the electronic device 200, or allow a larger enclosed volume 216 (and therefore a larger back volume) in the electronic device 200. In addition, including the IC 104 into the cavity 418 effectively embeds the IC 104 into the base 410, which may also increase the RF shielding of the sensor device 400. In one or more embodiments, the height ¾ can be about 0.3 mm to about 0.6 mm. Furthermore in the third example sensor device 400, since IC 104 is at least partially embedded into the base 410, its length or width or both dimensions can also be made smaller than the first and the second example sensor devices 100 and 300 shown in Figures 1 and 3.

[0039] Figure 5 shows a cross-sectional view of a fourth example sensor device 500. The fourth example sensor device 500 includes the base 110 defining the bottom port 132. An IC 504 is disposed on the front surface 116 of the base 110. The IC 504 can be soldered (using solder 534) to interconnects (not shown) on the front surface 116 to provide electrical connections between the IC 504 and the base 110. The IC 504 defines an opening 532 that is substantially aligned with the bottom port 132. For example, in one or more embodiments, a longitudinal axis of the bottom port 132 can be substantially aligned with a longitudinal axis of the opening 532 in the IC 504. The opening 532 allows acoustic energy entering from the bottom port 132 to be incident on the MEMS transducer 102. The MEMS transducer 102 can be disposed on top of the IC 504, such that the IC 504 lies between the MEMS transducer 102 and the base 110. The IC 504 can include interconnects on a surface of the IC 504 that faces the MEMS transducer 102. Solder 536 can connect interconnects on the MEMS transducer 102 to the interconnects on the IC 504 to provide electrical connection between the MEMS transducer 102 and the IC 504. In addition, the acoustically transparent cover 108 is disposed over the MEMS transducer 102 and extends along the sides of the MEMS transducer 102 and the IC 504 to make contact with the front surface 116 of the base 110. A conductive coating or layer 112 is disposed over the acoustically transparent cover 108 to electrically connect the acoustically transparent cover 108 to a ground plane on the base 110.

[0040] The stacking of the IC 504 and the MEMS transducer 102 over the base 110 can result in a footprint of the fourth example sensor device 500 that is smaller than that of the first, second, and the third example sensor devices 100, 300, and 400 discussed above in relation to Figures 1, 3, and 4, respectively. In one or more embodiments, the fourth example sensor device 500 can be used to implement the sensor 214 of the electronic device 200 discussed above in relation to Figure 2. Having a smaller footprint can free up valuable space within the electronic device 200, which can be utilized to include additional components within the electronic device 200, allow a reduction in overall size of the electronic device 200, or allow a larger enclosed volume 216 (and therefore a larger back volume) in the electronic device 200. In one or more embodiments, the height H₄ can be about 0.4 mm to about 0.8 mm .

[0041] Figure 6 shows a cross-sectional view of a fifth example sensor device 600. The fifth example sensor device 600 is similar to the fourth example sensor device 500 discussed above in relation to Figure 5, in that the IC 504 and the MEMS transducer 102 are stacked over each other. However, unlike the fourth example sensor device 500, in which the IC 504 was disposed on the front surface 116 of the base 110, the IC 504 in the fifth example sensor device 600 is instead disposed within a cavity 650 defined by a base 610. The base 610 defines the cavity 650 that extends between a front surface 616 and an indented surface 618. The IC 504 is soldered (using solder 634) onto interconnects (not shown) on the indented surface 618 of the base 610. The MEMS transducer 102 is soldered (using solder 636) to interconnects (not shown) on a surface of the IC 504 facing the MEMS transducer 102. The acoustically transparent cover 108 is disposed over the MEMS transducer 102 and extends between sidewalls of the cavity 650. The sidewalls of the base 610 can include interconnects that can electrically connect the acoustically transparent cover 108 to a ground plane. In one or more embodiments, the sidewalls of the cavity 650 can be coated with a conductive material such as metal, which makes electrical contact with a ground plane on the indented surface 618 and with the acoustically transparent cover 108. The acoustically transparent cover 108, the conductive sidewalls, and the ground plane on the indented surface 618 can form a shielded enclosure to electromagnetically shield the IC 504 and the MEMS transducer 102. In one or more embodiments, the acoustically transparent cover 108 can extend over the cavity 650 such that it makes contact with interconnects on the front surface 616 of the base 610.

[0042] By disposing the IC 504 and the MEMS transducer 102 within the cavity 650 of the base 610, a height of the fifth example sensor device 600 can be reduced. For example, the height of the fifth example sensor device 600 can be less than a height of the fourth example sensor device 500 discussed above in relation to Figure 5. In one or more embodiments, the fifth example sensor device 600 can be used to implement the sensor 214 of the electronic device 200 discussed above in relation to Figure 2. Having a smaller footprint of the fifth example sensor device 600 can free up valuable space within the electronic device 200, which can be utilized to include additional components within the electronic device 200, allow a reduction in overall size of the electronic device 200, or allow a larger enclosed volume 216 (and therefore a larger back volume) in the electronic device 200. In one or more

embodiments, the height Hs can be about 0.3 mm to about 0.6 mm. FIG. 7 shows an isometric view of a computer-aided design illustration of the fifth example sensor device 600, according to an example implementation.

[0043] Some embodiments of the present disclosure relate to a sensor including a base having a first surface and an opposing second surface, the base defining a bottom port extending between the first surface and the second surface; a microelectromechanical system (MEMS) transducer disposed on the base over the bottom port; an integrated circuit (IC) disposed on the base; and an acoustically transparent cover covering the MEMS transducer and the IC.

[0044] Some embodiments relate to a microphone including a base having a first surface and an opposing second surface, the base defining a bottom port extending between the first surface and the second surface; a microelectromechanical system (MEMS) acoustic transducer disposed on the base over the bottom port and configured to generate an electrical signal responsive to an acoustic signal; an integrated circuit (IC) disposed on the base; and an acoustically transparent cover covering the MEMS acoustic transducer and the IC, the acoustically transparent cover structured to transmit the acoustic signals between a volume enclosed by the acoustically transparent cover and a volume outside of the microphone.

[0045] Some embodiments relate to an electronic device including an airtight enclosure, the airtight enclosure defining an enclosed volume; a substrate disposed in the enclosed volume; and a sensor disposed on the substrate. The sensor includes a base having a first surface and a second surface, the base defining a bottom port extending between the first surface and the second surface, a microelectromechanical system (MEMS) transducer disposed on the base over the bottom port, an integrated circuit (IC) disposed on the base, and an acoustically transparent cover covering the MEMS transducer and the IC. [0046] 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.

[0047] 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.

[0048] 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.).

[0049] 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 indefmite 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).

[0050] 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.

[0051] 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.

Claims

WHAT IS CLAIMED IS:

1. A sensor comprising:

a base having a first surface and an opposing second surface, the base defining a bottom port extending between the first surface and the second surface;

a microelectromechanical system (MEMS) transducer disposed on the base over the bottom port;

an integrated circuit (IC) disposed on the base; and

an acoustically transparent cover covering the MEMS transducer and the IC.

2. The sensor of claim 1, further comprising a conductive coating disposed on the

acoustically transparent cover.

3. The sensor of claim 2, wherein the conductive coating has a thickness of about 10 pm to about 100 pm.

4. The sensor of claim 2, further comprising a ground interconnect disposed on the first surface, wherein the conductive coating is electrically connected to the ground interconnect.

5. The sensor of claim 1, wherein the specific acoustic impedance of the acoustically

transparent cover is less than 10,000 RaylMKS.

6. The sensor of claim 1, wherein the acoustically transparent cover includes a mesh.

7. The sensor of claim 6, wherein the mesh includes an interlaced network of at least one of a metal, a polymer, or a composite.

8. The sensor of claim 1, wherein the first surface defines a cavity, wherein the IC is at least partially disposed within the cavity.

9. The sensor of claim 1, wherein the IC is stacked between the base and the MEMS

transducer, and wherein the IC defines an opening aligned with the bottom port.

10. The sensor of claim 1, wherein the base defines a cavity, the first surface forming a bottom of the cavity, wherein the IC is stacked between the first surface and the MEMS transducer, and wherein the IC defines an opening aligned with the bottom port.

11. A microphone, comprising:

a microelectromechanical system (MEMS) acoustic transducer disposed on the base over the bottom port and configured to generate an electrical signal responsive to an acoustic signal;

an integrated circuit (IC) disposed on the base; and

an acoustically transparent cover covering the MEMS acoustic transducer and the IC, the acoustically transparent cover structured to transmit the acoustic signal between a volume enclosed by the acoustically transparent cover and a volume outside of the microphone.

12. The microphone of claim 11, further comprising a conductive coating disposed on the acoustically transparent cover.

13. The microphone of claim 12, wherein the conductive coating has a thickness of about 10 pm to about 100 pm.

14. The microphone of claim 12, further comprising a ground interconnect disposed on the first surface, wherein the conductive coating is electrically connected to the ground interconnect.

15. The microphone of claim 10, wherein the specific acoustic impedance of the acoustically transparent cover is less than 10,000 RaylMKS.

16. The microphone of claim 11, wherein the acoustically transparent cover includes a mesh.

17. The microphone of claim 16, wherein the mesh includes an interlaced network of at least one of a metal, a polymer, or a composite.

18. The microphone of claim 11, wherein the first surface defines a cavity, wherein the IC is at least partially disposed within the cavity.

19. The microphone of claim 11, wherein the IC is stacked between the base and the MEMS acoustic transducer, and wherein the IC defines an opening aligned with the bottom port.

20. The microphone of claim 11, wherein the base defines a cavity, the first surface forming a bottom of the cavity, wherein the IC is stacked between the first surface and the MEMS acoustic transducer, and wherein the IC defines an opening aligned with the bottom port.

21. An electronic device, comprising:

an airtight enclosure having an opening, the airtight enclosure defining an enclosed

volume;

a substrate disposed in the enclosed volume;

a sensor disposed on the substrate, the sensor including:

a base having a first surface and a second surface, the base defining a bottom port extending between the first surface and the second surface, the bottom port positioned to align with the opening in the airtight enclosure,

a microelectromechanical system (MEMS) transducer disposed on the base over the bottom port, the MEMS transducer separating the enclosed volume from the bottom port and the opening in the airtight enclosure,

an integrated circuit (IC) disposed on the base, and

an acoustically transparent cover covering the MEMS transducer and the IC.

22. The electronic device of claim 21, further comprising a conductive coating disposed over the acoustically transparent cover.

23. The electronic device of claim 22, further comprising a ground interconnect disposed on the first surface, wherein the conductive coating is electrically connected to the ground interconnect.

24. The electronic device of claim 21, wherein the specific acoustic impedance of the acoustically transparent cover is less than 10,000 RaylMKS.

25. The electronic device of claim 21, wherein the acoustically transparent cover includes a mesh.