Methods and systems for magnetic sensing

• US 8,058,870 B2
• Filed: 05/30/2008
• Issued: 11/15/2011
• Est. Priority Date: 05/30/2008
• Status: Expired due to Fees

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Sterling, James William
• Primary Examiner(s): LEDYNH, BOT L
• Application Number:
  US12/130,571
• Publication Number:
  US 20090294882A1
• Time in Patent Office: 1,264 Days
• Field of Search: 324251-252
• US Class Current: 324/252
• CPC Class Codes: G01R 33/072 Constructional adaptation of the sensor to specific applications
• CPC Class Codes: G01R 33/091 Constructional adaptation of the sensor to specific applications
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

One embodiment relates to a method of manufacturing a magnetic sensor. In the method, an engagement surface is provided. A magnet body is formed over the engagement surface by gradually building thickness of a magnetic material. The magnet body has a magnetic flux guiding surface that substantially corresponds to the engagement surface. Other apparatuses and methods are also set forth.

Claims

1. A method for forming a magnetic sensor, comprising

providing an engagement surface;

depositing an epoxy layer on the engagement surface, a surface of the epoxy layer formed having three planar surfaces; and

forming a magnet body over the engagement surface and on the epoxy layer by gradually building thickness of a magnetic material, the magnet body having a magnetic flux guidance surface having three planar surfaces and being substantially v-shaped to facilitate perpendicular guidance of magnetic field lines.

2. The method of claim 1, where gradually building thickness of the magnetic material comprises injection molding the magnetic material over the engagement surface.

3. The method of claim 2, where the magnetic material comprises a rare earth element.

4. The method of claim 2, where the magnetic material comprises ferrite.

5. The method of claim 1, where the engagement surface comprises an external surface of a lead frame or an external surface of an integrated circuit package.

6. The method of claim 5, further comprising:

providing at least one sensing element on the lead frame or in the integrated circuit package.

7. The method of claim 6, where the magnet body is formed to perpendicularly guide magnetic field lines through the at least one sensing element.

8. The method of claim 6, where the magnet body is formed to establish an approximately zero magnetic field condition in the at least one sensing element.

9. The method of claim 6, where the magnet body comprises a substantially conical surface that defines a recess in the magnet body, where the recess is positioned above the at least one sensing element.

12. The method of claim 1, where the magnetic flux guiding surface substantially corresponds to the engagement surface.

10. A method for forming a magnetic sensor, comprising:

providing an integrated circuit that comprises at least one sensing element;

forming an integrated circuit package over the integrated circuit, where the integrated circuit package comprises an engagement surface that facilitates alignment of a magnet body relative to the at least one sensing element; and

forming a magnetic flux guidance surface having three planar surfaces and being substantially v-shaped over the engagement surface.

11. The method of claim 10, where forming the magnetic flux guidance surface comprises:

forming the magnet body over the engagement surface by gradually building a thickness of a magnetic material over the engagement surface.

13. The method of claim 10, where the integrated circuit comprises at least one magneto resistive sensing element.

14. The method of claim 10, where the integrated circuit comprises at least one Hall sensing element.

15. A method for manufacturing a magnetic sensor, comprising:

providing a lead frame that comprises;

a die area and an engagement surface separated from one another by a bendable member;

providing a magnet body over the engagement surface;

bending the bendable member so the magnet body is positioned over or under the die area.

16. The method of claim 15, further comprising:

attaching an integrated circuit to the die area, where the integrated circuit includes at least one magnetic sensing element.

17. The method of claim 16, further comprising:

forming an integrated circuit package over the integrated circuit and magnet body.

18. A magnetic sensor, comprising

an integrated circuit comprising at least one sensing element;

an integrated circuit package overlying the integrated circuit, wherein the integrated circuit package comprises an engagement surface that facilitates alignment of a magnet body relative to the at least one sensing element; and

a magnetic flux guidance surface having three planar surfaces and being substantially v-shaped on the engagement surface.

19. The magnetic sensor of claim 18, wherein the magnetic flux guidance surface comprises:

a magnet body overlying the engagement surface, where the magnet body has the magnetic flux guiding surface that substantially corresponds to the engagement surface.

20. The magnetic sensor of claim 19, where a geometry of the magnet body is adapted to guide magnetic field lines in a predetermined manner with respect to the at least one sensing element.

21. The magnetic sensor of claim 19, where the magnet body is formed to perpendicularly guide magnetic field lines through the at least one sensing element.

22. The magnetic sensor of claim 19, where the magnet body is formed to establish an approximately zero magnetic field condition in the at least one sensing element.

23. The magnetic sensor of claim 19, where the magnet body comprises a substantially conical surface that defines a recess in the magnet body, where the recess is positioned above the at least one sensing element.

24. A magnetic sensor, comprising

an integrated circuit comprising at least one sensing element;

an integrated circuit package overlying the integrated circuit, wherein the integrated circuit package comprises an engagement surface;

an epoxy layer formed over the engagement surface of the integrated circuit package; and

a magnet body overlying the engagement surface and the epoxy layer, where the magnet body has a magnetic flux guiding surface that substantially corresponds to the engagement surface, the magnetic flux guiding surface having three planar surfaces and being substantially v-shaped.

25. The magnetic sensor of claim 24, where a geometry of the magnet body is adapted to guide magnetic field lines in a predetermined manner with respect to the at least one sensing element.

26. The magnetic sensor of claim 24, further comprising:

at least one intermediary layer between the engagement surface and the magnetic flux guiding surface.

27. The magnetic sensor of claim 24, where the engagement surface directly abuts the magnetic flux guiding surface.

28. The magnetic sensor of claim 24, where the geometry of the magnet body is adapted to perpendicularly guide magnetic field lines through the at least one sensing element.

29. The magnetic sensor of claim 24, where the geometry of the magnet body is adapted to establish an approximately zero magnetic field condition in the at least one sensing element.

30. The magnetic sensor of claim 24, where the magnet body comprises a conical surface that defines a recess in the magnet body above the at least one sensing element.

31. A magnetic sensor, comprising

an integrated circuit comprising at least one sensing element;

a magnet body comprising a magnetic flux guiding surface that is adapted to guide magnetic field lines in a predetermined manner with respect to the at least one sensing element, the magnetic flux guiding surface having three planar surfaces and being substantially v-shaped; and

an integrated circuit package overlying the integrated circuit and magnet body.

32. The magnetic sensor of claim 31, further comprising:

a lead frame abutting the magnet body.

33. The magnetic sensor of claim 32, where the lead frame comprises:

a die area and an engagement surface that are separated from one another by a bendable member.