Integrated circuit package having a split lead frame and a magnet

• US 9,411,025 B2
• Filed: 04/26/2013
• Issued: 08/09/2016
• Est. Priority Date: 04/26/2013
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: David, Paul, Vig, Ravi, Taylor, William P., Friedrich, Andreas P.
• Primary Examiner(s): Luu, Chuong A
• Assistant Examiner(s): FORTICH, RODOLFO D
• Application Number:
  US13/871,131
• Publication Number:
  US 20140320124A1
• Time in Patent Office: 1,201 Days
• Field of Search: 257/666, 257/421, 257/427, 257/108, 257/698
• US Class Current: 1/1
• CPC Class Codes: G01R 33/0047 Housings or packaging of magnetic sensors packaging of semiconductor devices H01L23/00; Holders
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/19105 in a side-by-side arrangement on a common die mounting substrate

Abstract

A magnetic field sensor includes a lead frame having a plurality of leads, at least two of which have a connection portion and a die attach portion. A semiconductor die is attached to the die attach portion of the at least two leads and a separately formed ferromagnetic element, such as a magnet, is disposed adjacent to the lead frame.

Claims

1. A magnetic field sensor comprising:

a lead frame having a first surface, a second opposing surface, and comprising a plurality of leads, wherein at least two of the plurality of leads are electrically isolated from each other and wherein each of the at least two leads has an elongated connection portion and a die attach portion;

a semiconductor die supporting a magnetic field sensing element and attached to the die attach portions of the at least two leads adjacent to the first surface of the lead frame with a non-conductive attachment mechanism;

a separately formed ferromagnetic element disposed adjacent to the lead frame; and

a passive component coupled to the at least two leads, wherein the die attach portion of at least one of the plurality of leads has a first portion that is separated from a second portion and wherein the magnetic field sensor further comprises a passive component coupled between the first portion and second portion of the die attach portion.

2. The magnetic field sensor of claim 1 wherein the ferromagnetic element comprises at least one of a sintered element or a molded element.

3. The magnetic field sensor of claim 1 wherein the ferromagnetic element is attached adjacent to the second surface of the lead frame.

4. The magnetic field sensor of claim 3 further comprising an attachment mechanism to attach the ferromagnetic element to the second surface of the lead frame.

5. The magnetic field sensor of claim 4 wherein the attachment mechanism comprises one or more of a non-conductive adhesive, epoxy, tape, film or spray.

6. The magnetic field sensor of claim 1 wherein the ferromagnetic element is comprised of a hard ferromagnetic material to form a permanent magnet.

7. The magnetic field sensor of claim 6 further comprising a second ferromagnetic element comprised of a soft ferromagnetic material.

8. The magnetic field sensor of claim 7 wherein the second ferromagnetic element is disposed adjacent to a surface of the lead frame opposite a surface of the lead frame to which the ferromagnetic element comprising a hard ferromagnetic material is disposed.

9. The magnetic field sensor of claim 7 wherein the second ferromagnetic element is disposed adjacent to the ferromagnetic element comprising a hard ferromagnetic material.

10. The magnetic field sensor of claim 1 wherein the ferromagnetic element is comprised of a soft ferromagnetic material to form a concentrator.

11. The magnetic field sensor of claim 10 further comprising a second ferromagnetic element comprised of a hard ferromagnetic material.

12. The magnetic field sensor of claim 1 further comprising a non-conductive mold material enclosing the semiconductor die and the die attach portion of the at least two leads.

13. The magnetic field sensor of claim 1 wherein the passive component is a capacitor.

14. The magnetic field sensor of claim 1 wherein the passive component is coupled to the die attach portion of the at least two leads.

15. The magnetic field sensor of claim 14 further comprising at least two passive components, each coupled between a respective pair of die attach portions.

16. The magnetic field sensor of claim 1 wherein the passive component is coupled to the connection portion of the at least two leads.

17. The magnetic field sensor of claim 1 wherein the passive component is a resistor.

18. The magnetic field sensor of claim 1 wherein the semiconductor die has a first surface in which the magnetic field sensing element is disposed and a second, opposing surface and wherein the second, opposing surface is attached to the die attach portion of the at least two leads.

19. The magnetic field sensor of claim 1 wherein the die attach portion of the at least two leads are spaced from each other.

20. The magnetic field sensor of claim 1 further comprising an electrical component supported by the semiconductor die.

21. The magnetic field sensor of claim 1 wherein the die attach portion of at least one of the plurality of leads comprises a separating feature to separate areas of the die attach portion from each other.

22. The magnetic field sensor of claim 21 wherein the die attach portion comprises at least two separating features and wherein an electrical connection is made from the semiconductor die to an area of the die attach portion between the at least two separating features.

23. The magnetic field sensor of claim 1 wherein the magnetic field sensing element comprises a Hall effect element.

24. The magnetic field sensor of claim 1 wherein the magnetic field sensing element comprises a magnetoresistive element.

25. The magnetic field sensor of claim 24 wherein the magnetoresistive element comprises one or more of a GMR element, a AMR element, a TMR element, and a MTJ element.

26. The magnetic field sensor of claim 1 wherein the non-conductive attachment mechanism comprises one or more of a non-conductive adhesive, epoxy, tape, film, or spray.

27. A magnetic field sensor comprising:

a lead frame having a first surface, a second opposing surface, and comprising a plurality of leads, wherein at least two of the plurality of leads are electrically isolated from each other and wherein each of the at least two leads has an elongated connection portion and a die attach portion;

a magnet attached to the die attach portions of the at least two leads adjacent to the first surface of the lead frame; and

a semiconductor die supporting a magnetic field sensing element and attached to the magnet and spaced from the lead frame by the magnet.

28. The magnetic field sensor of claim 27 wherein the magnet comprises at least one of a sintered element or a molded element.

29. The magnetic field sensor of claim 27 further comprising an attachment mechanism to attach the magnet to the second surface of the lead frame.

30. The magnetic field sensor of claim 29 wherein the attachment mechanism comprises one or more of a non-conductive adhesive, epoxy, tape, film or spray.

31. The magnetic field sensor of claim 27 further comprising a non-conductive mold material enclosing the semiconductor die and the die attach portion of the at least two leads.

32. The magnetic field sensor of claim 27 further comprising a passive component coupled to at least two of the plurality of leads.

33. The magnetic field sensor of claim 32 wherein the passive component is a capacitor.

34. The magnetic field sensor of claim 32 wherein the passive component is coupled to the die attach portion of the at least two leads.

35. The magnetic field sensor of claim 34 further comprising at least two passive components, each coupled between a respective pair of die attach portions.

36. The magnetic field sensor of claim 32 wherein the passive component is coupled to the connection portion of the at least two leads.

37. The magnetic field sensor of claim 27 wherein the die attach portion of at least one of the plurality of leads has a first portion that is separated from a second portion and wherein the magnetic field sensor further comprises a passive component coupled between the first portion and second portion of the die attach portion.

38. The magnetic field sensor of claim 37 wherein the passive component is a resistor.

39. The magnetic field sensor of claim 27 wherein the semiconductor die has a first surface in which the magnetic field sensing element is disposed and a second, opposing surface and wherein the second, opposing surface is attached to the die attach portion of the at least two leads.

40. The magnetic field sensor of claim 27 wherein the semiconductor die has a first surface in which the magnetic field sensing element is disposed and a second, opposing surface and wherein the first surface is attached to the die attach portion of the at least two leads.

41. The magnetic field sensor of claim 27 wherein the magnetic field sensing element comprises a Hall effect element.

42. The magnetic field sensor of claim 27 wherein the magnetic field sensing element comprises a magnetoresistive element.

43. The magnetic field sensor of claim 42 wherein the magnetoresistive element comprises one or more of a GMR element, a AMR element, a TMR element, and a MTJ element.

44. The magnetic field sensor of claim 37 wherein the passive component is coupled to the die attach portion of the at least two leads.

45. A magnetic field sensor comprising:

a lead frame having a first surface, a second opposing surface, and comprising a plurality of leads, wherein at least two of the plurality of leads are electrically isolated from each other and wherein each of the at least two leads has an elongated connection portion and a die attach portion;

a semiconductor die supporting a magnetic field sensing element and attached to the die attach portions of the at least two leads adjacent to the first surface of the lead frame with a non-conductive attachment mechanism;

a hard ferromagnetic element adjacent to the second surface of the lead frame; and

a soft ferromagnetic element coupled to the hard ferromagnetic element to form a concentrator.

46. The magnetic field sensor of claim 45 wherein the soft ferromagnetic element is disposed between the second surface of the lead frame and the hard ferromagnetic element.

47. The magnetic field sensor of claim 45 wherein the hard ferromagnetic element is disposed between the second surface of the lead frame and the soft ferromagnetic element.

48. The magnetic field sensor of claim 45 wherein the hard ferromagnetic element comprises at least one of a sintered element or a molded element.

49. The magnetic field sensor of claim 45 further comprising an attachment mechanism to attach the hard ferromagnetic element to the second surface of the lead frame.

50. The magnetic field sensor of claim 49 wherein the attachment mechanism comprises one or more of a non-conductive adhesive, epoxy, tape, film or spray.

51. The magnetic field sensor of claim 45 further comprising a non-conductive mold material enclosing the semiconductor die and the die attach portion of the at least two leads.

52. The magnetic field sensor of claim 45 further comprising a passive component coupled to at least two of the plurality of leads.

53. The magnetic field sensor of claim 52 wherein the passive component is a capacitor.

54. The magnetic field sensor of claim 52 wherein the passive component is coupled to the die attach portion of the at least two leads.

55. The magnetic field sensor of claim 54 further comprising at least two passive components, each coupled between a respective pair of die attach portions.

56. The magnetic field sensor of claim 52 wherein the passive component is coupled to the connection portion of the at least two leads.

57. The magnetic field sensor of claim 45 wherein the die attach portion of at least one of the plurality of leads has a first portion that is separated from a second portion and wherein the magnetic field sensor further comprises a passive component coupled between the first portion and second portion of the die attach portion.

58. The magnetic field sensor of claim 57 wherein the passive component is a resistor.

59. The magnetic field sensor of claim 45 wherein the magnetic field sensing element comprises a Hall effect element.

60. The magnetic field sensor of claim 45 wherein the magnetic field sensing element comprises a magnetoresistive element.

61. The magnetic field sensor of claim 60 wherein the magnetoresistive element comprises one or more of a GMR element, a AMR element, a TMR element, and a MTJ element.

62. The magnetic field sensor of claim 57 wherein the passive component is coupled to the die attach portion of the at least two leads.

63. The magnetic field sensor of claim 45 wherein the non-conductive attachment mechanism comprises one or more of a non-conductive adhesive, epoxy, tape, film, or spray.