Magnetic field sensor integrated circuit with an electromagnetic suppressor

• US 10,230,006 B2
• Filed: 06/09/2017
• Issued: 03/12/2019
• Est. Priority Date: 03/20/2012
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Vig, Ravi, Taylor, William P., David, Paul A., Scheller, P. Karl, Friedrich, Andreas P.
• Primary Examiner(s): Patidar, Jay
• Application Number:
  US15/618,251
• Publication Number:
  US 20170278981A1
• Time in Patent Office: 641 Days
• CPC Class Codes: G01D 2205/40 Position sensors comprising arrangements for concentrating or redirecting magnetic flux
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01R 15/207 Constructional details independent of the type of device used
• CPC Class Codes: G01R 33/0047 Housings or packaging of magnetic sensors packaging of semiconductor devices H01L23/00; Holders
• CPC Class Codes: G01R 33/0052 Manufacturing aspects; Manufacturing of single devices, i.e. of semiconductor magnetic sensor chips devices based on galvano-magnetic effect or the like H10N50/85
• CPC Class Codes: G01R 33/06 using galvano-magnetic devices
• CPC Class Codes: H01L 2224/45147 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73215 Layer and wire connectors
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 29/82 controllable by variation of the magnetic field applied to the device
• 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 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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
• CPC Class Codes: H01L 2924/01033 Arsenic [As]

Abstract

A magnetic field sensor includes a lead frame, a semiconductor die having a first surface in which a magnetic field sensing element is disposed and a second surface attached to the lead frame, and a non-conductive mold material enclosing the die and at least a portion of the lead frame. The sensor may include a ferromagnetic mold material secured to a portion of the non-conductive mold material. An electromagnetic suppressor comprising a ferromagnetic material encloses a passive device spaced from the non-conductive mold material and coupled to a plurality of leads.

Claims

1. A magnetic field sensor comprising:

a lead frame having a first surface, a second opposing surface, and a plurality of leads;

a semiconductor die having a first surface in which a magnetic field sensing element is disposed and a second opposing surface attached to the first surface of the lead frame;

a non-conductive mold material enclosing the die and at least a portion of the lead frame;

a passive component coupled to the plurality of leads and spaced from the non-conductive mold material;

an electromagnetic suppressor comprising a molded ferromagnetic material enclosing the passive component; and

a ferromagnetic mold material secured to a portion of the non-conductive mold material, wherein the ferromagnetic mold material comprises a central aperture having a surface extending from the non-conductive mold material to an outer peripheral surface of the ferromagnetic mold material, wherein the surface of the central aperture comprises a bend at an intermediate location such that the surface of the central aperture has a first slope from the non-conductive mold material to the bend and a second slope different than the first slope from the bend to the outer peripheral surface of the central aperture.

2. The magnetic field sensor of claim 1 wherein at least one of the electromagnetic suppressor and the ferromagnetic mold material comprises a hard ferromagnetic material.

3. The magnetic field sensor of claim 2 wherein the hard ferromagnetic material is selected from the group consisting of a ferrite, a SmCo alloy, a NdFeB alloy, a thermoplastic polymer with hard magnetic particles, or a thermoset polymer with hard magnetic particles.

4. The magnetic field sensor of claim 1 wherein at least one of the electromagnetic suppressor and the ferromagnetic mold material comprises a soft ferromagnetic material.

5. The magnetic field sensor of claim 4 wherein the soft ferromagnetic material is selected from the group consisting of NiFe, Ni, a Ni alloy, steel or ferrite.

6. The magnetic field sensor of claim 1 wherein the electromagnetic suppressor comprises a first mold element enclosing the passive component and a second mold element enclosing at least a portion of the first mold element.

7. The magnetic field sensor of claim 6 wherein the non-conductive mold material enclosing the die and at least a portion of the lead frame comprises a first non-conductive mold material and wherein the first mold element comprises a second non-conductive mold material.

8. The magnetic field sensor of claim 7 wherein the second non-conductive mold material comprises a thermoset or a thermoplastic.

9. The magnetic field sensor of claim 7 wherein the first non-conductive mold material and the second non-conductive mold material comprise the same material.

10. The magnetic field sensor of claim 6 wherein the second mold element comprises a ferromagnetic material.

11. The magnetic field sensor of claim 10 wherein the second mold element comprises a hard ferromagnetic material.

12. The magnetic field sensor of claim 10 wherein the second mold element comprises a soft ferromagnetic material.

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

14. A magnetic field sensor, comprising:

a lead frame having a first surface, a second opposing surface, and a plurality of leads;

a semiconductor die having a first surface in which a magnetic field sensing element is disposed and a second opposing surface;

a non-conductive mold material enclosing the die and at least a portion of the lead frame;

a ferromagnetic mold material secured to a portion of the non-conductive mold material, wherein the ferromagnetic mold material comprises a central aperture having a surface extending from the non-conductive mold material to an outer peripheral surface of the ferromagnetic mold material, wherein the surface of the central aperture comprises a bend at an intermediate location such that the surface of the central aperture has a first slope from the non-conductive mold material to the bend and a second slope different than the first slope from the bend to the outer peripheral surface of the central aperture;

at least one capacitor coupled to at least two of the plurality of leads and spaced from the non-conductive mold material; and

an electromagnetic suppressor comprising a molded ferromagnetic material enclosing the at least one capacitor.

15. The magnetic field sensor of claim 14 wherein the electromagnetic suppressor comprises a hard ferromagnetic material.

16. The magnetic field sensor of claim 14 wherein the electromagnetic suppressor comprises a soft ferromagnetic material.

17. The magnetic field sensor of claim 14 wherein the electromagnetic suppressor comprises a first mold element enclosing the at least one capacitor and a second mold element enclosing at least a portion of the first mold element.

18. The magnetic field sensor of claim 17 wherein the non-conductive mold material enclosing the die and at least a portion of the lead frame comprises a first non-conductive mold material and wherein the first mold element comprises a second non-conductive mold material.

19. The magnetic field sensor of claim 17 wherein the ferromagnetic mold material secured to a portion of the non-conductive mold material comprises a first ferromagnetic mold material and wherein the second mold element comprises a second ferromagnetic mold material.

20. A magnetic field sensor, comprising:

a lead frame having a first surface, a second opposing surface, and a plurality of leads;

a semiconductor die having a first surface in which a magnetic field sensing element is disposed and a second opposing surface;

a first non-conductive mold material enclosing the die and at least a portion of the lead frame;

a first ferromagnetic mold material secured to a portion of the non-conductive mold material wherein the first ferromagnetic mold material comprises a central aperture having a surface extending from the first non-conductive mold material to an outer peripheral surface of the first ferromagnetic mold material, wherein the surface of the central aperture comprises a bend at an intermediate location such that the surface of the central aperture has a first slope from the first non-conductive mold material to the bend and a second slope different than the first slope from the bend to the outer peripheral surface of the central aperture;

at least one capacitor coupled to at least two of the plurality of leads and spaced from the non-conductive mold material; and

a suppression device comprising;

a first mold element enclosing the at least one capacitor and comprising a second non-conductive mold material; and

a second mold element enclosing at least a portion of the first mold element and comprising a second ferromagnetic mold material.

21. The magnetic field sensor of claim 20 wherein the second non-conductive mold material comprises a thermoset or a thermoplastic.

22. The magnetic field sensor of claim 20 wherein the second ferromagnetic mold material comprises a hard ferromagnetic mold material.

23. The magnetic field sensor of claim 22 wherein the hard ferromagnetic mold material is selected from the group consisting of a ferrite, a SmCo alloy, a NdFeB alloy, a thermoplastic polymer with hard magnetic particles, or a thermoset polymer with hard magnetic particles.

24. The magnetic field sensor of claim 20 wherein the second ferromagnetic mold material comprises a soft ferromagnetic mold material.

25. The magnetic field sensor of claim 24 wherein the soft ferromagnetic mold material is selected from the group consisting of NiFe, Ni, a Ni alloy, steel or ferrite.