Electromagnetic interference shielding of MEMS microphone via printed circuit board
An assembly is provided which includes a package and a printed circuit board. The package includes a housing bounding a region and an acoustic sensor within the region. The housing includes a base with a first hole. The sensor is configured to generate signals indicative of sound received by the sensor through the first hole. The printed circuit board is in mechanical communication with the base and includes a second hole aligned with the first hole such that sound received by the second hole propagates through the first hole to the sensor. The printed circuit board further includes an electrically conductive layer, at least a portion of which extends across the second hole and is configured to allow the sound to propagate through the second hole and to at least partially shield the region containing the sensor from electromagnetic interference.
1. An assembly comprising:
a package comprising a housing bounding a region and an acoustic sensor within the region, the housing comprising a base with a first hole, the sensor configured to generate signals indicative of sound received by the sensor through the first hole; and
a printed circuit board in mechanical communication with the base, the printed circuit board comprising:
a second hole aligned with the first hole such that sound received by the second hole propagates through the first hole to the sensor; and
an electrically conductive layer, at least a portion of the layer extending across the second hole, the portion configured to allow the sound to propagate through the second hole and to at least partially shield the region containing the sensor from electromagnetic interference.
2. The assembly of claim 1 , wherein the sensor comprises a microelectromechanical system (MEMS) microphone.
3. The assembly of claim 1 , wherein the base comprises:
a first surface and a second surface opposite to the first surface, the first hole extending from the first surface to the second surface; and
first circuitry in electrical communication with the sensor, the sensor mounted on the first surface within the region.
4. The assembly of claim 3 , wherein the first circuitry comprises at least one integrated circuit mounted on the first surface within the region and in electrical communication with the sensor.
5. The assembly of claim 3 , wherein the printed circuit board comprises a third surface and a fourth surface opposite to the third surface, the second hole extending from the third surface to the fourth surface.
6. The assembly of claim 5 , wherein the first surface of the base comprises a plurality of electrically conductive first pads and the second surface of the base comprises a plurality of electrically conductive second pads, the sensor in electrical communication with the first pads, the printed circuit board comprising a plurality of electrically conductive third pads on the third surface, at least some of the third pads in electrical communication with the second pads of the base.
7. The apparatus of claim 1 , wherein the electrically conductive layer comprises a mesh.
8. The apparatus of claim 1 , wherein the electrically conductive layer is in electrical communication with an electrical ground.
9. The assembly of claim 1 , further comprising second circuitry mounted on the printed circuit board, the second circuitry in electrical communication with the package.
10. The assembly of claim 1 , further comprising:
a biocompatible casing containing the package and the printed circuit board; and
a gasket sandwiched between a portion of the casing and the printed circuit board, the gasket comprising a third hole and the portion of the casing comprising a fourth hole, the third hole and the fourth hole aligned with the first hole and the second hole such that sound received by the fourth hole propagates through the fourth, third, second, and first holes to the sensor.
11. A method comprising:
providing a microphone package comprising an acoustic port, the package configured to be surface-mounted onto a printed circuit board and configured to generate signals indicative of sound received by the acoustic port;
providing the printed circuit board, the printed circuit board comprising a hole and an electrically conductive layer extending across the hole; and
mounting the package onto a surface of the printed circuit board such that sound received by the hole propagates to the acoustic port.
12. The method of claim 11 , wherein said mounting comprises aligning the acoustic port with the hole.
13. The method of claim 12 , wherein said mounting further comprises soldering electrically conductive pads of the package to electrically conductive pads of the printed circuit board.
14. The method of claim 11 , wherein the electrically conductive layer is configured to mitigate electromagnetic interference and/or electrostatic discharge from damaging a sensor within the package or otherwise adversely affecting performance of the package.
15. The method of claim 11 , wherein the hole and the electrically conductive layer are configured to have a predetermined acoustic impedance.
16. The method of claim 11 , further comprising, after mounting the package onto the surface of the printed circuit board, placing the package and the printed circuit board within a biocompatible casing configured to be implanted in a recipient.
17. The assembly of claim 1 , wherein
the sensor comprises a microphone comprising a pressure transducer and having a first frequency response to pressure waves, the electrically conductive layer comprising
an electrically conductive mesh within the second hole, the second hole and the mesh configured to alter an acoustic impedance of the second hole such that the assembly has a second frequency response to pressure waves different from the first frequency response.
18. The assembly of claim 17 , wherein the microphone is surface-mountable and the pressure transducer is a microelectromechanical system (MEMS) pressure transducer.
19. The assembly of claim 17 , wherein the microphone further comprises an acoustic port in fluidic communication with the pressure transducer and with the second hole of the printed circuit board.
20. The assembly of claim 17 , wherein the microphone further comprises a plurality of first terminals and the printed circuit board further comprises a plurality of second terminals mounted to the plurality of first terminals.
21. The assembly of claim 20 , wherein the plurality of first terminals is on a planar outer surface of the microphone.
22. The assembly of claim 20 , wherein the microphone comprises a plurality of electrically conductive first layers in electrical communication with the plurality of first terminals.
23. The assembly of claim 22 , wherein the printed circuit board comprises a plurality of electrically conductive second layers in electrical communication with the plurality of second terminals.
24. The assembly of claim 17 , wherein the mesh is configured to at least partially shield the pressure transducer from electromagnetic interference (EMI) and/or electrostatic discharge (ESD).
25. The assembly of claim 24 , wherein the second hole and the mesh are configured to have a predetermined acoustic impedance.
26. The assembly of claim 24 , wherein the mesh has a hatched polygonal pattern with an aperture size, thickness, and number of apertures.
27. The assembly of claim 26 , wherein the mesh is configured to have a predetermined shielding effectiveness for mitigating EMI and/or ESD from damaging or otherwise adversely affecting performance of the assembly.