Current sensor

• US 7,476,816 B2
• Filed: 04/10/2006
• Issued: 01/13/2009
• Est. Priority Date: 08/26/2003
• Status: Expired due to Term

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Taylor, William P., Doogue, Michael C., Mangtani, Vijay
• Primary Examiner(s): Ngo; Hung V
• Application Number:
  US11/401,160
• Publication Number:
  US 20060181263A1
• Time in Patent Office: 1,009 Days
• Field of Search: 324/117.H, 174/528, 174/532, 257/672, 257/676
• US Class Current: 174/528
• CPC Class Codes: G01R 1/36 Overload-protection arrangements or circuits for electric measuring instruments
• CPC Class Codes: G01R 15/202 using Hall-effect devices Hall elements in arrangements for measuring electrical power G01R21/08
• CPC Class Codes: G01R 15/207 Constructional details independent of the type of device used
• CPC Class Codes: G01R 33/07 Hall effect devices
• CPC Class Codes: H01L 2224/13101 the principal constituent melting at a temperature of less than 400°C
• CPC Class Codes: H01L 2224/13111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/13144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/1319 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/16245 the item being metallic
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/37147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/37599 Material
• CPC Class Codes: H01L 2224/40095 Kinked
• CPC Class Codes: H01L 2224/40245 the item being metallic
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/4826 Connecting between the body and an opposite side of the item with respect to the body
• CPC Class Codes: H01L 2224/4903 Connectors having different sizes, e.g. different diameters
• CPC Class Codes: H01L 2224/73215 Layer and wire connectors
• CPC Class Codes: H01L 2224/73221 : Strap and wire connectors
• CPC Class Codes: H01L 2224/81801 : Soldering or alloying
• CPC Class Codes: H01L 2224/81805 : involving forming a eutectic alloy at the bonding interface
• CPC Class Codes: H01L 2224/8185 : using a polymer adhesive, e.g. an adhesive based on silicone, epoxy, polyimide, polyester
• CPC Class Codes: H01L 2224/84 : using a strap connector
• CPC Class Codes: H01L 24/16 : of an individual bump connector
• CPC Class Codes: H01L 24/37 : of an individual strap connector
• CPC Class Codes: H01L 24/40 : of an individual strap connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• 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 2924/00014 : 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 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/1306 : Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/19104 : on the semiconductor or solid-state device, i.e. passive-on-chip

Abstract

An integrated circuit current sensor includes a lead frame having at least two leads coupled to provide a current conductor portion, and a substrate having a first surface in which is disposed one or more magnetic field sensing elements, with the first surface being proximate to the current conductor portion and a second surface distal from the current conductor portion. In one particular embodiment, the substrate is disposed having the first surface of the substrate above the current conductor portion and the second surface of the substrate above the first surface. In this particular embodiment, the substrate is oriented upside-down in the integrated circuit in a flip-chap arrangement. The lead frame also includes a shunt conductor portion formed as a coupling of the at least two leads.

Claims

1. A current sensor, comprising:

a lead frame comprising;

a plurality of leads;

a first current conductor portion comprising at least two of the plurality of leads, wherein the first current conductor portion is adapted to carry a first portion of a current; and

a shunt conductor portion comprising a coupling of the at least two of the plurality of leads, wherein the shunt conductor portion is adapted to carry a second portion of the current;

a substrate having first and second opposing surfaces, the first surface proximate to the first current conductor portion and the second surface distal from the first current conductor portion; and

one or more magnetic field transducers disposed on the first surface of said substrate.

2. The current sensor of claim 1, wherein said shunt conductor portion has a size and a shape selected to provide a selected resistance, which is selected to carry the second portion of the current.

3. The current sensor of claim 1, wherein each one of the leads has a bend in a direction selected to result in each one of the leads being closer to the first surface of the substrate than to the second surface of the substrate throughout a length of the lead.

4. The current sensor of claim 1, wherein the first current conductor portion comprises another coupling of the at least two of the plurality of leads and wherein said one or more magnetic field transducers are disposed proximate to the first current conductor portion.

5. The current sensor of claim 1, further comprising a second current conductor portion deposited on the first surface of the substrate, disposed proximate to the one or more magnetic field transducers, and coupled to the first current conductor portion.

6. The current sensor of claim 1, further comprising an insulating layer disposed between the first surface of the substrate and the first current conductor portion.

7. The current sensor of claim 1, further comprising a flux shield disposed generally between the shunt conductor portion and the one or more magnetic field transducers.

8. The current sensor of claim 1, further comprising a flux concentrator disposed on the shunt conductor portion.

9. The current sensor of claim 1, wherein said substrate has at least one bonding pad coupled to a corresponding one of the plurality of leads with a bond wire.

10. The current sensor of claim 1, wherein said substrate is coupled to said lead frame with a selected one of a solder ball, a gold bump, a eutectic and high lead solder bump, a no-lead solder bump, a gold stud bump, a polymeric conductive bump, an anisotropic conductive paste, or a conductive film coupled to a corresponding one of the plurality of leads.

11. The current sensor of claim 1, wherein at least a part of the first current conductor portion has a T-shaped cross section, the T-shaped cross section taken through a thickness direction of the first current conductor portion, the T-shaped cross section resulting in an increased magnetic field proximate to the first current conductor portion, and therefore, proximate to said one or more magnetic field transducers.

12. The current sensor of claim 1, wherein at least a part of the first current conductor portion has a thinned rectangular cross section having a minimum dimension less than a thickness of other portions of said lead frame, the thinned rectangular cross section taken through a thickness direction of the first current conductor portion, the thinned rectangular cross section resulting in an increased magnetic field proximate to the first current conductor portion, and therefore, proximate to said one or more magnetic field transducers.

13. The current sensor of claim 1, further comprising at least one amplifier disposed on said substrate.

14. The current sensor of claim 1, wherein the substrate and the lead frame are relatively disposed in a flip-chip arrangement resulting in said first current conductor portion being proximate to said one or more magnetic field transducers, and further resulting in an increased sensitivity of the integrated circuit to a magnetic field.

15. A current sensor, comprising:

a lead frame having a plurality of leads;

a current conductor portion comprising at least two of the plurality of leads, wherein the first-current conductor portion is adapted to carry a first portion of a current;

a shunt conductor portion comprising a coupling of the at least two of the plurality of leads, wherein the shunt conductor portion is adapted to carry a second portion of the current;

a substrate having first and second opposing surfaces, the first surface proximate to said current conductor portion and the second surface distal from said current conductor portion; and

one or more magnetic field transducers disposed on the first surface of said substrate, wherein the substrate and the lead frame are relatively disposed in a flip-chip arrangement resulting in the current conductor portion being proximate to said one or more magnetic field transducers, and further resulting in an increased sensitivity of the integrated circuit to a magnetic field.

16. The current sensor of claim 15, wherein said substrate is coupled to said lead frame with a selected one of a solder ball, a gold bump, a eutectic and high lead solder bump, a no-lead solder bump, a gold stud bump, a polymeric conductive bump, an anisotropic conductive paste, or a conductive film coupled to a corresponding one of the plurality of leads.

17. The current sensor of claim 15, wherein each one of the leads has a bend in a direction selected to result in each one of the leads being closer to the first surface of the substrate than to the second surface of the substrate throughout a length of the lead.

18. A current sensor, comprising:

a lead frame having a plurality of leads;

a current conductor portion comprising at least two of the plurality of leads, wherein the current conductor portion is adapted to carry a first portion of a current;

a shunt conductor portion comprising a coupling of the at least two of the plurality of leads, wherein at least one of the current conductor portion or the shunt conductor portion is formed as a conductive clip coupled to the at least two of the plurality of leads, and wherein the shunt conductor portion is adapted to carry a second portion of the current;

a substrate having first and second opposing surfaces, the first surface proximate to said current conductor portion and the second surface distal from said current conductor portion; and

one or more magnetic field transducers disposed on the first surface of said substrate.

19. The current sensor of claim 18, wherein said substrate is disposed having the first surface of said substrate above said conductive clip and the second surface of said substrate above the first surface.

20. The current sensor of claim 18, wherein said substrate is disposed having the first surface of said substrate below said conductive clip and the second surface below the first surface.

21. A current sensor, comprising:

a lead frame having a plurality of leads;

a current conductor portion comprising at least two of the plurality of leads, wherein the current conductor portion is adapted to carry a first portion of a current;

a shunt conductor portion comprising a coupling of the at least two of the plurality of leads, wherein the shunt conductor portion is adapted to carry a second portion of the current;

a substrate having first and second opposing surfaces, the first surface proximate to said current conductor portion and the second surface distal from said first current conductor portion;

one or more magnetic field transducers disposed on the first surface of said substrate; and

a flux concentrator disposed on the shunt conductor portion.

22. The current sensor of claim 21, wherein each one of the leads has a bend in a direction selected to result in each one of the leads being closer to the first surface of the substrate than to the second surface of the substrate throughout a length of the lead.

23. The current sensor of claim 21, wherein the substrate and the lead frame are relatively disposed in a flip-chip arrangement resulting in the current conductor portion being proximate to said one or more magnetic field transducers, and further resulting in an increased sensitivity of the integrated circuit to a magnetic field.