Finger sensor including capacitive lens and associated methods

• US 8,803,258 B2
• Filed: 04/14/2011
• Issued: 08/12/2014
• Est. Priority Date: 04/15/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: AuthenTec Incorporated (Apple Inc.)
• Inventors: Gozzini, Giovanni, Bond, Robert H.
• Primary Examiner(s): ARMAND, MARC ANTHONY
• Application Number:
  US13/086,694
• Publication Number:
  US 20110254108A1
• Time in Patent Office: 1,216 Days
• Field of Search: 257/415, 257/E27.006, 257/E21.705
• US Class Current: 257/415
• CPC Class Codes: G06V 40/1329 Protecting the fingerprint sensor against damage caused by the finger
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

A finger sensing device may include a mounting substrate, an integrated circuit (IC) die carried by the mounting substrate and having an array of electric field-based finger sensing elements, and first electrical connections coupling the mounting substrate and the IC die. In addition, the finger sensing device may include a protective plate attached over the array of electric field-based finger sensing elements and having a dielectric constant greater than 5 in all directions and a thickness greater than 40 microns to define a capacitive lens for the array of electric field-based finger sensing elements. The finger sensing device may also include an encapsulating material adjacent the mounting substrate and the IC die and around at least the first electrical connections.

Claims

1. A finger sensing device comprising:

a mounting substrate;

an integrated circuit (IC) die carried by said mounting substrate and comprising an array of electric field-based finger sensing elements;

a plurality of first electrical connections coupling said mounting substrate and said IC die;

a protective plate attached over said array of electric field-based finger sensing elements;

an encapsulating material adjacent said mounting substrate and said IC die and around at least said plurality of first electrical connections; and

at least one electrical conductor carried by said protective plate.

2. The finger sensing device according to claim 1 wherein said protective plate has a dielectric constant less than 20.

3. The finger sensing device according to claim 1 wherein said protective plate has a thickness less than 100 microns.

4. The finger sensing device according to claim 1 further comprising at least one second electrical connection coupling said at least one electrical conductor and said mounting substrate.

5. The finger sensing device according to claim 1 further comprising at least one optical device;

and

wherein said protective plate is transparent and covers said at least one optical device.

6. The finger sensing device according to claim 1 wherein said plurality of first electrical connections comprises a plurality of bonding wires.

7. The finger sensing device according to claim 1 wherein said protective plate is flush with adjacent upper portions of said encapsulating material.

8. The finger sensing device according to claim 1 wherein said protective plate comprises a top over said array of electric field-based sensing elements, and a sidewall extending downwardly from said top and wrapping around at least said encapsulating material.

9. The finger sensing device according to claim 1 wherein said protective plate comprises at least one of electrical glass, photographic glass, pyrex glass, window glass, electrical mica and nylon.

10. The finger sensing device according to claim 1 further comprising a first adhesive layer securing said IC die and said mounting substrate together;

and a second adhesive layer securing said protective plate and said IC die together.

11. The finger sensing device according to claim 1, wherein said protective plate has a dielectric constant greater than 5 in all directions and a thickness greater than 40 microns to define a capacitive lens for said array of electric field-based finger sensing elements.

12. A finger sensing device comprising:

a mounting substrate;

an integrated circuit (IC) die carried by said mounting substrate and comprising an array of electric field-based finger sensing elements;

a plurality of first electrical connections coupling said mounting substrate and said IC die, said plurality of first electrical connections comprising a plurality of bond wires;

a protective plate attached over said array of electric field-based finger sensing elements and having a dielectric constant greater than 5 in all directions and a thickness greater than 40 microns to define a capacitive lens for said array of electric field-based finger sensing elements;

an encapsulating material adjacent said mounting substrate and said IC die and around at least said plurality of first electrical connections;

at least one electrical conductor carried by said protective plate; and

at least one second electrical connection coupling said at least one electrical conductor and said mounting substrate.

13. The finger sensing device according to claim 12 wherein said protective plate has a dielectric constant less than 20.

14. The finger sensing device according to claim 12 further comprising at least one optical device;

and wherein said protective plate is transparent and covers said at least one optical device.

15. The finger sensing device according to claim 12 wherein said protective plate is flush with adjacent upper portions of said encapsulating material.

16. The finger sensing device according to claim 12 wherein said protective plate comprises a top over said array of electric field-based sensing elements, and a sidewall extending downwardly from said top and wrapping around at least said encapsulating material.

17. The finger sensing device according to claim 12 wherein said protective plate comprises at least one of electrical glass, photographic glass, pyrex glass, window glass, electrical mica and nylon.

18. A method for making a finger sensing device comprising:

mounting an integrated circuit (IC) die on a mounting substrate and comprising an array of electric field-based finger sensing elements;

establishing a plurality of first electrical connections coupling the mounting substrate and the IC die;

securing a protective plate over the array of electric field-based finger sensing elements;

forming an encapsulating material adjacent the mounting substrate and the IC die and around at least the plurality of first electrical connections; and

forming at least one electrical conductor carried by the protective plate.

19. The method according to claim 18 wherein the protective plate has a dielectric constant less than 20.

20. The method according to claim 18 wherein the protective plate has a thickness less than 100 microns.

21. The method according to claim 18 further comprising forming at least one second electrical connection coupling the at least one electrical conductor and the mounting substrate.

22. The method according to claim 18 further comprising providing at least one optical device;

and wherein the protective plate is transparent and covers the at least one optical device.

23. The method according to claim 18 wherein the protective plate comprises at least one of electrical glass, photographic glass, pyrex glass, window glass, electrical mica and nylon.

24. The method according to claim 18, wherein securing the protective plate over the array of electric field-based finger sensing elements comprises securing a protective plate over the array of electric field-based finger sensing elements and having a dielectric constant greater than 5 in all directions and a thickness greater than 40 microns to define a capacitive lens for the array of electric field-based finger sensing elements.