Parylene electret condenser microphone backplate
A microphone assembly comprising a housing, a single flexible diaphragm, and a rigid backplate. The backplate may be coated with a parylene configured to help reduce the flatness deviation of the backplate across the diameter of the backplate. A plurality of openings may extend from the top portion of the backplate to the bottom portion of the backplate.
1. A microphone assembly comprising:
a housing having a top and a bottom, the housing further comprising:
a flexible diaphragm located above a backplate assembly; and
a spacer intermediate the diaphragm and backplate assembly, the spacer creating an air gap between the diaphragm and backplate;
wherein the backplate assembly is coupled to the housing and further comprises:
a body comprising:
a diameter;
a top side; and
a bottom side;
wherein a coating of vapor-deposited electret material coats the top side of the body;
wherein the body has a flatness deviation across the diameter of the body configured to help prevent the diaphragm from collapsing onto the backplate assembly; and
wherein the coating of vapor-deposited electret material comprises parylene-AF4.
2. The microphone assembly according to claim 1 , wherein the body of the backplate comprises a printed circuit board.
3. The microphone assembly according to claim 1 , wherein the coating of vapor-deposited electret material is at least 20 microns thick.
4. The microphone assembly according to claim 1 , wherein the backplate exhibits a maximum initial charge capacity of −1900 volts.
5. The microphone assembly of claim 1 , wherein the body of the backplate comprises a metalized ceramic.
6. The microphone assembly of claim 1 , wherein the body of the backplate comprises a metalized plastic.
7. The microphone assembly of claim 1 , wherein the backplate assembly further comprises a plurality of perforations that extend from the top side of the body through the bottom side of the body, wherein the coating of vapor-deposited electret material coats a plurality of inside diameters of the plurality of perforations.
8. A microphone assembly comprising:
a housing having a top and a bottom, the housing further comprising:
a flexible diaphragm located above a backplate assembly; and
a spacer intermediate the diaphragm and backplate assembly, the spacer creating an air gap between the diaphragm and backplate;
wherein the backplate assembly is coupled to the housing and further comprises:
a body comprising:
a diameter;
a top side; and
a bottom side;
wherein a coating of vapor-deposited electret material coats the top side of the body;
wherein the body has a flatness deviation across the diameter of the body configured to help prevent the diaphragm from collapsing onto the backplate assembly; and
wherein the flatness deviation across the diameter of the body measures 10 percent or less of the height of the air gap.
9. The microphone assembly of claim 8 , wherein the coating of vapor-deposited electret material comprises parylene-AF4.
10. The microphone assembly of claim 8 , wherein the coating of vapor-deposited electret material is at least 20 microns think.
11. The microphone assembly of claim 8 , wherein the body of the backplate comprises metalized plastic.
12. The microphone assembly of claim 8 , wherein the body of the backplate comprises metalized ceramic.
13. The microphone assembly of claim 8 , wherein the body of the backplate comprises a printed circuit board.
14. A microphone assembly comprising:
a housing having a top and a bottom, the housing further comprising:
a flexible diaphragm located above a backplate assembly; and
a spacer intermediate the diaphragm and backplate assembly, the spacer creating an air gap between the diaphragm and backplate;
wherein the backplate assembly is coupled to the housing and further comprises:
a body comprising:
a diameter;
a top side; and
a bottom side;
wherein a coating of vapor-deposited electret material coats the top side of the body;
wherein the body has a flatness deviation across the diameter of the body configured to help prevent the diaphragm from collapsing onto the backplate assembly; and
wherein the backplate assembly further comprises a plurality of perforations that extend from the top side of the body through the bottom side of the body, wherein the coating of vapor-deposited electret material coats a plurality of inside diameters of the plurality of perforations.
15. The backplate assembly according to claim 14 , wherein the coating of vapor-deposited electret material comprises parylene-AF4.
16. The microphone assembly of claim 14 , wherein the body of the backplate comprises a printed circuit board.
17. The microphone assembly of claim 14 , wherein the flatness deviation across the diameter of the body measures 10 percent or less of the height of the air gap.
18. A microphone assembly comprising:
a housing having a top and a bottom, the housing further comprising:
a flexible diaphragm located above a backplate assembly; and
a spacer intermediate the diaphragm and backplate assembly, the spacer creating an air gap between the diaphragm and backplate;
wherein the backplate assembly is coupled to the housing and further comprises:
a body comprising:
a diameter;
a top side; and
a bottom side;
wherein a coating of vapor-deposited electret material coats the top side of the body;
wherein the body has a flatness deviation across the diameter of the body configured to help prevent the diaphragm from collapsing onto the backplate assembly; and
wherein the body of the backplate comprises at least one of a metalized plastic or a metalized ceramic.
19. The microphone assembly according to claim 18 , wherein the body of the backplate comprises a metalized ceramic.
20. The microphone assembly of claim 18 , wherein the coating of vapor-deposited electret material is at least 20 microns thick.
21. The microphone assembly of claim 18 , wherein the backplate assembly further comprises a plurality of perforations that extend from the top side of the body through the bottom side of the body, wherein the coating of vapor-deposited electret material coats a plurality of inside diameters of the plurality of perforations.