Electronic device having a sealed biometric input system

1. A portable electronic device, comprising:

a housing member defining a side surface of the portable electronic device, a portion of the housing member defining a side wall of a hole extending through the housing member;

a button member positioned along the side surface and defining:

a chassis portion; and

a hollow post extending into the hole defined through the housing member;

a first waterproof seal defined between the hollow post and the side wall of the hole;

a biometric sensing component coupled to the chassis portion;

a flexible circuit element extending through the hollow post and conductively coupling the biometric sensing component to a component within the portable electronic device; and

a second waterproof seal defined within the hollow post.

2. The portable electronic device of claim 1 , wherein:

the biometric sensing component is configured to capture a representation of a fingerprint of a user;

the portable electronic device is configured to authenticate the user using the representation of the fingerprint; and

the portable electronic device further comprises an input sensor configured to detect an input force applied to the button member.

3. The portable electronic device of claim 1 , wherein the first waterproof seal comprises an O-ring.

4. The portable electronic device of claim 1 , wherein the second waterproof seal comprises a potting material at least partially filling the hollow post.

5. The portable electronic device of claim 1 , further comprising a sapphire cap attached to the chassis portion and covering the biometric sensing component.

6. The portable electronic device of claim 5 , further comprising a third waterproof seal between the sapphire cap and the chassis portion.

7. The portable electronic device of claim 6 , wherein:

the second waterproof seal is formed from a first curable liquid having a first viscosity; and

the third waterproof seal is formed from a second curable liquid having a second viscosity that is lower than the first viscosity.

8. A portable electronic device, comprising:

a housing member defining a side wall of a hole extending through the housing member;

a display;

a transparent cover over the display and coupled to the housing member;

a button member positioned along a side of the housing member and defining:

a chassis portion; and

a post extending from the chassis portion and positioned at least partially in the hole, the post defining a passage extending through the post from the chassis portion to an end of the post;

a biometric sensing component coupled to the chassis portion; and

a flexible circuit element extending through the passage and conductively coupling the biometric sensing component to a component within the portable electronic device.

9. The portable electronic device of claim 8 , further comprising:

a sealing member in contact with an exterior surface of the post and the side wall of the hole and configured to inhibit ingress of liquid between the exterior surface of the post and the side wall of the hole; and

a potting material within the passage and at least partially encapsulating the flexible circuit element, the potting material configured to inhibit ingress of liquid through the passage.

10. The portable electronic device of claim 9 , wherein the potting material at least partially encapsulates the biometric sensing component.

11. The portable electronic device of claim 8 , wherein:

the hole is a first hole;

the housing member defines a second hole extending through the housing member; and

the button member further defines an additional post extending from the chassis portion and positioned in the second hole.

12. The portable electronic device of claim 11 , wherein the additional post is a solid post.

13. The portable electronic device of claim 11 , further comprising an anti-roll bar retained to the housing member and coupled to the post and the additional post, the anti-roll bar configured to maintain uniform travel of the post and the additional post during actuation of the button member.

14. The portable electronic device of claim 8 , wherein the portable electronic device further comprises an input sensor configured to detect an input force applied to the button member.

15. The portable electronic device of claim 14 , wherein the input sensor is a capacitive sensor.

16. A portable electronic device, comprising:

a housing defining a side surface of the portable electronic device;

a display at least partially within the housing;

a transparent cover over the display and coupled to the housing;

a button member positioned along the side surface and defining a hollow post extending into a hole defined through the housing;

a biometric sensing component coupled to the button member;

a cap covering the biometric sensing component and secured to the button member;

a flexible circuit element extending through the hollow post and electrically coupling the biometric sensing component to a component within the housing; and

a potting material at least partially encapsulating the flexible circuit element and the biometric sensing component and at least partially filling the hollow post.

17. The portable electronic device of claim 16 , wherein the button member further defines a solid post extending into an additional hole defined through the housing.

18. The portable electronic device of claim 17 , further comprising:

a first sealing member positioned between the hollow post and a first surface of the housing that defines the hole; and

a second sealing member positioned between the solid post and a second surface of the housing that defines additional hole.

19. The portable electronic device of claim 16 , further comprising a sealing material positioned in a gap defined between the cap and the button member.

20. The portable electronic device of claim 16 , wherein the biometric sensing component is a capacitive sensor of a fingerprint sensing system.