ELECTROSTATIC DISCHARGE (ESD) MITIGATION FOR IN-EAR AUDIO OUTPUT DEVICES

1 . An in-ear audio output device, comprising:

an earbud housing;

a nozzle coupled to an external surface of the earbud housing and configured to extend towards an ear canal of an ear of a wearer of the in-ear audio output device and comprising a planar, distal end having one or more apertures to conduct sound waves to the ear canal of the wearer;

a substrate positioned within the earbud housing and the nozzle, the substrate comprising:

a first portion;

a second portion comprising a first edge of the substrate proximate the one or more apertures;

a metal layer on a top surface of the second portion extending, at least, to the first edge of the substrate; and

a first coverlay on a top surface of a portion of the metal layer of the substrate, the first coverlay comprising a second edge proximate the one or more apertures, wherein the second edge is a greater distance away from the one or more apertures than the first edge; and

a microphone surrounded by a metal casting attached to a bottom surface of the substrate, the metal casing comprising a third edge proximate the one or more apertures, wherein the third edge is a greater distance from the one or more apertures than the first edge.

2 . The in-ear audio output device of claim 1 , wherein the third edge is a greater distance away from the one or more apertures than the second edge.

3 . The in-ear audio output device of claim 1 , wherein:

the substrate further comprises a second coverlay on a bottom surface of the substrate; and

the microphone surrounded by the metal casing is attached to the second coverlay.

4 . The in-ear audio output device of claim 3 , wherein the first coverlay and the second coverlay comprise polyimide.

5 . The in-ear audio output device of claim 1 , wherein the metal layer comprises a copper layer.

6 . The in-ear audio output device of claim 1 , wherein the metal layer is electrically grounded.

7 . The in-ear audio output device of claim 1 , further comprising:

a metal stiffener on a top surface of the first coverlay of the substrate comprising a fourth edge proximate the one or more apertures, wherein the fourth edge is a greater distance away from the one or more apertures than the first edge.

8 . The in-ear audio output device of claim 7 , wherein the fourth edge is a same distance away from the one or more apertures as the second edge.

9 . The in-ear audio output device of claim 1 , wherein:

a length of the metal casing surrounding the microphone is less than a length of the second portion of the substrate; and

the metal casing surrounding the microphone is centered on the bottom surface of the substrate such that the first edge of the substrate and the third edge of the metal casing are separated by a distance.

10 . The in-ear audio output device of claim 1 , further comprising:

a metal mesh near the one or more apertures, wherein the metal mesh minimizes an electrostatic discharge entering through the one or more apertures.

11 . The in-ear audio output device of claim 1 , further comprising:

a substantially spherical dome shaped sealing structure extending from the planar, distal end of the nozzle.

12 . The in-ear audio output device of claim 1 , wherein the substrate comprises a printed circuit board.

13 . The in-ear audio output device of claim 12 , wherein the printed circuit board is flexible.

14 . An in-ear audio output device, comprising:

an earbud housing;

a nozzle coupled to an external surface of the earbud housing and comprising a planar, distal end including one or more apertures;

a substrate positioned within the earbud housing and the nozzle, the substrate comprising:

a first portion comprising a first edge of the substrate proximate the one or more apertures;

a metal layer on a top surface of the first portion extending, at least, to the first edge of the substrate; and

a first coverlay on a top surface of a portion of the metal layer of the substrate, the first coverlay comprising a second edge proximate the one or more apertures; and

a microphone surrounded by a metal casting attached to a bottom surface of the substrate, the metal casing comprising a third edge proximate the one or more apertures.

15 . The in-ear audio output device of claim 14 , wherein the second edge is a greater distance away from the one or more apertures than the first edge, wherein the third edge is a greater distance from the one or more apertures than the first edge, and wherein the third edge is a greater distance away from the one or more apertures than the second edge.

16 . The in-ear audio output device of claim 14 , wherein:

the substrate further comprises a second coverlay on a bottom surface of the substrate; and

the microphone surrounded by the metal casing is attached to the second coverlay.

17 . The in-ear audio output device of claim 16 , wherein the first coverlay and the second coverlay comprise polyimide.

18 . The in-ear audio output device of claim 14 , wherein the metal layer comprises a copper layer.

19 . The in-ear audio output device of claim 14 , further comprising:

a metal stiffener on a top surface of the first coverlay of the substrate comprising a fourth edge proximate the one or more apertures, wherein the fourth edge is a greater distance away from the one or more apertures than the first edge.

20 . The in-ear audio output device of claim 14 , wherein the substrate comprises a flexible printed circuit board.