Current transducer with leadframe conductors and sensor die for circuit board mounting

Abstract

A current transducer configured for surface mount connection to a circuit board comprising : - a leadframe arrangement (6) including primary conductor terminals (7) having a first connection pad (7a) and a second connection pad (7b) and a secondary conductor terminals (8), formed out of a single common strip of sheet metal, - a magnetic field sensor die (2) having one or more magnetic field sensing portions (3a, 3b) and connection points interconnected via interconnects (9) to the secondary conductor terminals (8), - an insulating material overmold (4) encapsulating the magnetic field sensor die and leadframe arrangement (6) except for contact portions, and - a primary conductor module (5) comprising a primary conductor (14) and an insulating primary conductor overmold (16) encapsulating the primary conductor except for surfaces of terminal portions on a mounting side of the primary conductor module.

Description

[0001] CURRENT TRANSDUCER WITH LEADFRAME CONDUCTORS AND SENSOR DIE FOR CIRCUIT BOARD MOUNTING

[0002] The present invention relates to a single package current transducer for surface mount connection on a circuit board, the current transducer including primary and secondary conductors formed from a leadframe and a sensor die in an overmold housing.

[0003] Current transducers including primary and secondary conductors formed from a leadframe and including an integrated circuit sensor die in an overmold housing are well known. Typically, the primary conductor, which carries the current to be measured, is stamped out of the same leadframe as the secondary conductors that are connected via bond wires to connection points on the integrated circuit of the sensor die. The use of a leadframe to form the secondary and primary conductors is well known and has the advantage of allowing the conductors to be stamped and formed from a strip of sheet metal in a rapid automated manner, the leadframe being overmolded while the conductors are interconnected, the conductors then being separated by a cutting operation after the overmolding. This allows a low-cost high volume manufacturing process that is well known in the art.

[0004] Before overmolding, a magnetic field sensor die is mounted over a portion of the primary conductor. In order to increase measurement sensitivity, it is advantageous for the magnetically sensitive portions of the sensor die to be positioned close to the primary conductor. On the other hand, the sensor die should be separated from the primary conductor by an insulation layer that is sufficient to avoid any electrical breakdown or creepage between the primary conductor and the sensor die, this requirement depending on the voltage of the primary current to be measured. There is also a continuous need in many applications to reduce the size of transducers while increasing measurement accuracy and ability to measure currents with relatively high voltages, for instance of a few hundred volts. In view of the increasing implementation of electrical motors and other systems and the associated need to measure electrical parameters, the cost of transducers is an important factor as well.

[0005] One of the drawbacks of using leadframe technology for the integration of primary and secondary conductors in a single package current transducer, is the maximum thickness of the leadframe which limits the flexibility of adjusting current transducers for different applications with different power levels (different voltages and different currents) and different types of magnetic field sensors. Having to change the leadframe base material for different transducers increases manufacturing costs. Also, if a thicker leadframe is provided in order to have a primary conductor with a higher current carrying capacity, this increases the overall cost of the transducer and means that even the secondary conductor arrangement is made of the same leadframe even though the increased material thickness is not required for the secondary conductors.

[0006] Depending on the application, sensor dies with different magnetic field sensing technologies, for instance Hall effect sensors, tunnel magneto resistance (TMR) sensors and others may be implemented. The configuration of the sensor die may require a different layout of the primary conductor portion that is positioned proximate the sensing elements of the magnetic field sensor. For each different application, leadframe stamping tool needs to have a dedicated configuration as well as the assembly processes of the sensor die on the leadframe arrangement.

[0007] In view of the above, an object of the invention is to provide a single package current transducer for mounting and connection on a circuit board that is compact, and economical to manufacture for different versions.

[0008] It is advantageous to provide a current transducer that is reliable and durable.

[0009] It is advantageous to provide a current transducer that can support relatively high voltages yet have a very compact arrangement for circuit board mounting.

[0010] It is advantageous to provide a current transducer that can be adapted for different sensor dies, including TMR sensor dies.

[0011] Objects of this invention have been achieved by providing a system and a method according to the independent claims. Dependent claims set forth various advantageous features of embodiments of the invention.

[0012] Disclosed herein is a current transducer configured for surface mount connection to a circuit board comprising :

[0013] - a leadframe arrangement including primary conductor terminals having a first connection pad and a second connection pad and a secondary conductor terminals, formed out of a single common strip of sheet metal,

[0014] - a magnetic field sensor die having one or more magnetic field sensing portions and connection points interconnected via interconnects to the secondary conductor terminals, and

[0015] - an insulating material overmold encapsulating the magnetic field sensor die and leadframe arrangement except for contact portions. The current transducer further comprises a primary conductor module comprising:

[0016] - a primary conductor having a first terminal portion, a second terminal portion and a bridging portion, and

[0017] - an insulating primary conductor overmold (16) encapsulating the primary conductor except for surfaces of the first and second terminal portions on a mounting side of the primary conductor module.

[0018] The first terminal portion is mounted on and electrically connected to the first primary conductor pad and the second terminal portion mounted on and electrically connected to the second primary conductor pad, the first and second primary conductor pads separated by an insulating gap. A thickness of the primary conductor is greater than a thickness of the leadframe arrangement. The magnetic field sensor die is mounted on a top surface of the primary conductor module. Edges of the magnetic field sensor die are separated from the primary conductor terminals of the leadframe arrangement by a spacing extending across a surface of the primary conductor module.

[0019] In an advantageous embodiment, the primary conductor module comprises an insulating layer mounted on top of the primary conductor overmold, the insulating layer made of a material having a higher electrical breakdown resistance than a material forming the primary conductor overmold.

[0020] In an advantageous embodiment, the insulating layer is selected from a group of materials comprising glass or polyimide.

[0021] In an advantageous embodiment, the insulating layer is assembled on a top surface of the primary conductor overmold with an insulating adhesive layer.

[0022] In an advantageous embodiment, the primary conductor terminals of the leadframe arrangement each span over more than 30% of a width of the current transducer.

[0023] In an advantageous embodiment, the primary conductor of the primary conductor module comprises a recess along the bridging portion, the recess extending into the primary conductor from a mounting side.

[0024] In an advantageous embodiment, a width of the connection portions of the primary conductor of the primary conductor module is more than 80% of a width of the primary conductor terminals, said width being measured in a direction orthogonal to a direction of flow of primary current between the first connection terminal and second connection terminal.

[0025] In an advantageous embodiment, the first connection portion and second connection portion of the primary conductor of the primary conductor module are connected to the respective primary conductor terminals by a solder connection.

[0026] In an advantageous embodiment, the magnetic field sensor die is surrounded on at least three edges by a spacing extending across a top wall of the primary conductor module to an edge of the primary conductor module.

[0027] In an advantageous embodiment, the primary conductor module comprises an overhang such that the top surface of the primary conductor module has a larger surface area than a mounting surface area of the primary conductor module positioned against the primary conductor terminal.

[0028] In an advantageous embodiment, the overhang is formed by the primary conductor overmold or by an insulating layer mounted on a top wall of the primary conductor overmold.

[0029] In an advantageous embodiment, the magnetic field sensor die comprises at least two magnetic field sensing portions spaced apart overhead the bridging portion of the primary conductor of the primary conductor module for measuring a differential magnetic field or an inplane magnetic field gradient.

[0030] In an advantageous embodiment, the sensor die comprises two or at least two tunnel magneto resistance (TMR) portions.

[0031] In an advantageous embodiment, the interconnects between the magnetic field sensor die and the secondary conductor terminals consist of bond wires.

[0032] Also disclosed herein is a method of manufacturing a current transducer according to any of the preceding embodiments, comprising the steps of :

[0033] - stamping and forming out of a single strip of sheet metal the leadframe arrangement comprising the primary conductor terminals and the secondary terminals;

[0034] - separately forming the primary conductor module including stamping and forming the primary conductor out of a second sheet of metal, overmolding the primary conductor with an insulating material, bonding an insulating layer on a top surface of the primary conductor overmold, bonding the magnetic field sensor die on top of the insulating layer,

[0035] - mounting and interconnecting the primary conductor module on top of the primary conductor terminal of the leadframe arrangement, interconnecting the secondary terminals to connection terminals of the magnetic field sensor die, and

[0036] -overmolding the leadframe arrangement, primary conductor module and magnetic field sensor die with an insulating polymer material.

[0037] In an advantageous embodiment, primary conductor overmold is overmolded by injection molding of a thermosetting or thermoplastic polymer.

[0038] In an advantageous embodiment, the primary conductor module is mounted on the primary conductor terminals by soldering the primary conductor pads of the primary conductor module to the primary conductor terminals of the leadframe arrangement.

[0039] In an advantageous embodiment, the overmold housing is molded while the leadframe arrangement is attached to the primary conductor terminals and secondary conductor terminals.

[0040] Further objects and advantageous features of the invention will be apparent from the claims, from the detailed description, and annexed drawings, in which:

[0041] Figure 1a is a perspective view of a current transducer according to an embodiment of the invention, showing an overmold housing in transparency;

[0042] Figure 1 b is a perspective view of a mounting side of the current transducer of figure 1a;

[0043] Figure 1c is a cross-sectional view through lines 1c-1c of figure 1a;

[0044] Figure 2 is a view similar to figure 1a, of a variant, in particular a variant having a different primary conductor arrangement compared to the variant of figure 1a;

[0045] Figure 3a is a perspective view of an underside of a primary conductor module of a current transducer according to an embodiment of the invention;

[0046] Figure 3b is a cross-sectional view through lines 3b-3b of figure 3a; Figure 4 is a view similar to figure 3b of a variant.

[0047] Referring to the figures, a current transducer 1 comprises a leadframe arrangement 6, a primary conductor module 5, a magnetic field sensor die 2, and an overmold housing 4 encapsulating the magnetic field sensor die, primary conductor module 5 and leadframe arrangement 6 except for contact regions and sectioned edges.

[0048] The leadframe arrangement 6 comprises primary conductor terminals 7 and secondary conductor terminals 8, the primary conductor terminals for connection to a conductor carrying the current to be measured, and the secondary conductor terminals 8 for connection to terminals supplying power to the sensor die 2 and for receiving measurement signals from the sensor die 2. The configuration of primary conductor terminals and secondary conductor terminals 8 and their connection to corresponding circuitry of a circuit board are per se well known to those skilled in the art and do not need to be described in detail herein.

[0049] The primary conductor terminals and secondary conductor terminals 8 are cut out of the same strip of sheet metal commonly termed a leadframe, such leadframe technology for forming primary and secondary conductors being per se well known in the art. The leadframe has a maximum thickness that is defined by the thickness of the strip of sheet metal. Certain portions of the leadframe may have a reduced thickness that may be formed by a stamping operation or by a subtractive manufacturing operation such as etching, such technologies also being well known in the art. The leadframe passes through a stamping and forming die and may also have portions that are bent out of the original plane of sheet metal, although in the embodiments illustrated this is not the case, but could be as needed.

[0050] The secondary conductor terminals 8 are arranged along one edge of the transducer and the primary conductor arranged adjacent an opposed opposite edge of the square or rectangular transducer. As well known, since the primary conductor may be at a high voltage (up to a few hundred volts) compared to the secondary conductors which are only at a few volts, there is an advantage in maintaining a large spacing between the secondary conductors and primary conductor. The secondary conductor terminals 8 may be interconnected to secondary connection points on the sensor die 2 via bond wires 9 as per se well known in the art. The bond wires may also be connected to conductive traces formed on a substrate on which the sensor die is mounted, whereby the connection points or pads on the sensor die may be connected to those conductive traces via a perse known flip-chip connection arrangement. The magnetic field sensor die 2 may typically be in the form of an integrated circuit, made of a semiconductor with magnetic field sensing portions 3a, 3b thereon. There are various known magnetic field sensing technologies formed with integrated circuits, for instance Hall effect sensors and tunnel magneto resistance (TMR) sensors. These may be arranged to measure a magnetic field intensity orthogonal to the surface of the integrated circuit or in-plane with the surface of the magnetic field sensor, depending on the technology employed. In most cases, it is advantageous to have the magnetic field sensing portions 3a, 3b close to a portion of the primary conductor to increase the sensitivity and thus accuracy of the measurement. It is typical to provide the primary conductor with a reduced cross-section in the vicinity of the placement of the magnetic field sensing portions in order to increase the current density in the zone close to the magnetic field sensing portions. This may be done by locally reducing the width of the primary conductor at a position of the magnetic field sensing portions, or locally reducing the thickness of the primary conductor, or both locally reducing the width and the thickness of the primary conductor.

[0051] According to an aspect of the invention, the current transducer comprises a primary conductor module 5 including a primary conductor 14 overmolded by an insulating material forming a primary conductor overmold 16, the primary conductor module 5 mounted on the primary conductor terminals 7 of the leadframe arrangement 6. The primary conductor terminals 7 of the leadframe arrangement 6 comprises a first connection pad 7a and a second connection pad 7b that are separated by an insulating gap 21 , whereby the primary conductor 14 of the primary conductor module 5 spans across this insulating gap 21 and interconnects electrically the first connection pad 7a to the second connection pad 7b.

[0052] The primary conductor 14 has a first terminal portion 14a that is mounted against and connected to the first connection pad 7a, and a second terminal portion 14b mounted against and connected to the second connection pad 7b. The connection between the primary conductor 14 and primary conductor terminal 7 may be by way of solder connection, or by welding, or by a conductive adhesive bonding technique. The primary conductor terminal portions 14a, 14c are interconnected by a bridging portion 14c that has a reduced cross-section compared to the terminal portions 14a, 14b in order to increase the current density through the bridging portion 14c.

[0053] The magnetic sensor die 2 has one or more magnetic sensing portions 3a, 3b that are positioned overhead, directly or in an laterally offset manner, the bridging portion 14c of the primary conductor 14. In the illustrated embodiment, the bridging portion 14c has not only a reduced width l / V, measured in a plane of the sensor die orthogonal to a direction of current flow, but also a reduced height (thickness) hi measured in a direction orthogonal to the plane of the sensor die.

[0054] The primary conductor 14 of the primary conductor module 5 may be formed also from a leadframe, however from a different leadframe than the leadframe 6 used for forming the primary conductor and secondary conductor terminals 7, 8. It may in particular be formed from a leadframe formed from a strip of sheet metal having a smaller width, for instance a width corresponding to the width of the primary conductor terminals 7, or a width less than the width of the primary conductor terminals 7. The thickness H of the sheet material forming the primary conductor 14 of the primary conductor module 5 is greater than the thickness of the leadframe arrangement 6 that forms the primary and secondary conductor terminals 7, 8. A center portion forming the bridging portion 14c may, in preferred embodiments, have a reduced height or thickness hi. The reduction in material thickness is preferably formed by a recess 24 extending from the connection side 23 of the primary conductor module such that the bridging branch 14c remains as close as possible to a top side 25 of the primary conductor module.

[0055] Advantageously, the sheet material forming the primary conductor 14 may be selected to have a thickness and geometric configuration that is optimized for the parameters of the current to be measured and the magnetic field sensor die characteristics, while the leadframe arrangement 6 may be a standard invariable component to which different primary conductor modules may be assembled.

[0056] The primary conductor module 5 also advantageously increases the insulation resistance and creepage distance between the primary conductor and the magnetic field sensor die in a very compact arrangement because the primary conductor 14 is provided in an overmolded insulating housing presenting a top surface on which an additional insulating layer made of a higher resistance insulating material such as glass, polyimide foil, or per se known high insulation die attach films, may be mounted.

[0057] For instance, the overmold housing of the primary conductor module may be made of an epoxy or other type of high voltage insulating polymers that may advantageously be easily overmolded on the leadframe forming the primary conductor 14 which may be formed in a continuous strip and cut to the required length for a cost-effective high volume manufacturing thereof.

[0058] The insulation layer 18 may be made of a high insulating material, preferably selected from glass, polyimide foil, or per se known high insulation die attach films. The surface area of the top of the primary conductor module is greater than the surface area of the magnetic field sensor die 2, such that the sensor die is positioned on the top of the primary conductor module with the edges of the sensor die being separated by a distance D1, D2, D3, D4 from edges of the primary conductor module 5. The creepage distance between the sensor die and the primary conductor, in particular the primary conductor terminals 7, is thus increased.

[0059] In a variant, the primary conductor overmold 16 may comprise an overhang 22 that extends beyond perimeter of the mounting side 23, this feature also increasing the creepage distance between the sensor die and the primary conductor terminal 7. The overhang may be from 0,4mm to 5mm or more.

[0060] Depending on the configuration of the primary conductor 14 and the magnetic field sensor die 2 and sensing portions 3a, 3b, the primary conductor module may either be fully within the outer boundaries of the primary conductor terminals or may be positioned in an overhang manner as illustrated in figure 2 such that the primary conductor module 5 extends beyond at least one of the lateral edges of the primary conductor module. In such case, the edge of the magnetic field sensor die 2 may be at or close to the edge of the primary conductor module 5 in view of the overhang that increases the creepage distance between the sensor die and the primary conductor terminals 7.

[0061] The magnetic field sensor die 2 may be mounted on the insulating layer 18 with a die attach film comprising an adhesive as perse known in the art of die attach films.

[0062] The advantage of the primary conductor module according to embodiments of the invention is to be able to produce different primary conductor arrangements optimized for different magnetic field sensor dies while ensuring a high insulation and creepage distance with respect to the primary conductor terminals 7 and at the same time enabling the provision of a standard or invariable leadframe arrangement 6 and transducer footprint for economical high volume manufacturing of single package current transducers. List of references used

[0063] Current transducer 1

[0064] Magnetic field sensor die 2

[0065] First sensing portion 3a

[0066] Second sensing portion 3b

[0067] Connection points

[0068] Bonding layer (die attach film)

[0069] Overmold housing 4

[0070] Mounting side 12

[0071] Primary conductor module 5

[0072] Primary conductor 14

[0073] First terminal portion 14a

[0074] Second terminal portion 14b

[0075] Bridging portion 14c

[0076] Recess 24

[0077] Primary conductor overmold 16

[0078] Insulating layer 18

[0079] Bonding layer 19

[0080] Overhang 22

[0081] Lead frame arrangement 6

[0082] Primary conductor terminals 7

[0083] First connection pad 7a

[0084] Second connection pad 7b

[0085] Surface mount connection side

[0086] Secondary conductor terminals 8

[0087] Surface mount pads

[0088] Interconnects 9

[0089] Bond wires

[0090] Primary conductor thickness H

Claims

Claims1. A current transducer configured for surface mount connection to a circuit board comprising :- a leadframe arrangement (6) including primary conductor terminals (7) having a first connection pad (7a) and a second connection pad (7b) and a secondary conductor terminals (8), formed out of a single common strip of sheet metal,- a magnetic field sensor die (2) having one or more magnetic field sensing portions (3a, 3b) and connection points interconnected via interconnects (9) to the secondary conductor terminals (8), and- an insulating material overmold (4) encapsulating the magnetic field sensor die and leadframe arrangement (6) except for contact portions, characterized in that the current transducer further comprises a primary conductor module (5) comprising:- a primary conductor (14) having a first terminal portion (14a), a second terminal portion (14b) and a bridging portion (14c), and- an insulating primary conductor overmold (16) encapsulating the primary conductor except for surfaces of the first and second terminal portions on a mounting side of the primary conductor module, the first terminal portion mounted on and electrically connected to the first primary conductor pad (7a) and the second terminal portion mounted on and electrically connected to the second primary conductor pad (7b), the first and second primary conductor pads (7a, 7b) separated by an insulating gap (21), a thickness ( / 7) of the primary conductor (14) being greater than a thickness of the leadframe arrangement (6), the magnetic field sensor die (2) being mounted on a top surface of the primary conductor module (5), edges of the magnetic field sensor die being separated from the primary conductor terminals (7) of the leadframe arrangement (6) by a spacing (D1 , D2, D3, D4) extending across a surface of the primary conductor module, wherein the primary conductor module comprises an insulating layer (18) mounted on top of the primary conductor overmold, the insulating layer made of a material having a higher electrical breakdown resistance than a material of the primary conductor overmold (16).

2. The current transducer according to claim 1 wherein the insulating layer is selected from a group of materials consisting of glass or polyimide.

3. The current transducer according to claim 2 wherein the insulating layer (18) is assembled on a top surface of the primary conductor overmold (16) with an insulating adhesive layer.

4. The current transducer according to any preceding claim wherein the primary conductor (14) of the primary conductor module (5) comprises a recess (24) along the bridging portion (14c), the recess extending into the primary conductor from a mounting side (23).

5. The current transducer according to any preceding claim wherein the first connection portion (14a) and second connection portion (14b) of the primary conductor (14) are connected to the respective primary conductor terminals (7a, 7b) by a solder connection.

6. The current transducer according to any preceding claim wherein the magnetic field sensor die is surrounded on at least three edges by a spacing extending across a top wall of the primary conductor module to an edge of the primary conductor module.

7. The current transducer according to any preceding claim wherein the primary conductor module comprises an overhang (22) such that the top surface of the primary conductor module has a larger surface area than a mounting surface area of the primary conductor module positioned against the primary conductor terminal (7).

8. The current transducer according to the preceding claim wherein the overhang (22) is formed by the primary conductor overmold (16) or by an insulating layer (18) mounted on a top wall of the primary conductor overmold.

9. The current transducer according to any preceding claim wherein the magnetic field sensor die comprises at least two magnetic field sensing portions (3a, 3b) spaced apart overhead the bridging portion (14c) of the primary conductor (14) for measuring a differential magnetic field or an in-plane magnetic field gradient.

10. The current transducer according to any preceding claim wherein the sensor die comprises two or at least two tunnel magneto resistance (TMR) portions.11 . The current transducer according to any preceding claim wherein the interconnects (9) between the magnetic field sensor die (2) and the secondary conductor terminals (8) consist of bond wires.

12. A method of manufacturing a current transducer according to any of the preceding claims, comprising the steps of- stamping and forming out of a single strip of sheet metal the leadframe arrangement comprising the primary conductor terminals and the secondary terminals (8),- separately forming the primary conductor module (5) including stamping and forming the primary conductor (14) out of a second sheet of metal, overmolding the primary conductor (14) with an insulating material, bonding the insulating layer (18) on a top surface of the primary conductor overmold (16), bonding the magnetic field sensor die (2) on top of the insulating layer (18),- mounting and interconnecting the primary conductor module on top of the primary conductor terminal (7) of the leadframe arrangement (6), interconnecting the secondary terminals (8) to connection terminals of the magnetic field sensor die,-overmolding the leadframe arrangement (6), primary conductor module (5) and magnetic field sensor die with an insulating polymer material.

13. The method of the preceding claim wherein the primary conductor overmold is overmolded by injection molding of a thermosetting or thermoplastic polymer.

14. The method of either of the two directly preceding claims wherein the primary conductor module is mounted on the primary conductor terminals by soldering the primary conductor pads of the primary conductor module to the primary conductor terminals (7a, 7b) of the leadframe arrangement (6).

15. A current transducer configured for surface mount connection to a circuit board comprising :- a leadframe arrangement (6) including primary conductor terminals (7) having a first connection pad (7a) and a second connection pad (7b) and a secondary conductor terminals (8), formed out of a single common strip of sheet metal,- a magnetic field sensor die (2) having one or more magnetic field sensing portions (3a, 3b) and connection points interconnected via interconnects (9) to the secondary conductor terminals (8), and- an insulating material overmold (4) encapsulating the magnetic field sensor die and leadframe arrangement (6) except for contact portions, characterized in that the current transducer further comprises a primary conductor module (5) comprising:- a primary conductor (14) having a first terminal portion (14a), a second terminal portion (14b) and a bridging portion (14c), and- an insulating primary conductor overmold (16) encapsulating the primary conductor except for surfaces of the first and second terminal portions on a mounting side of the primaryconductor module, the insulating primary conductor overmold extending between the mounting side and a top surface, the first terminal portion mounted on and electrically connected to the first primary conductor pad (7a) and the second terminal portion mounted on and electrically connected to the second primary conductor pad (7b), the first and second primary conductor pads (7a, 7b) separated by an insulating gap (21), a thickness ( / 7) of the primary conductor (14) being greater than a thickness of the leadframe arrangement (6), the magnetic field sensor die (2) being mounted on the top surface of the primary conductor module (5), edges of the magnetic field sensor die being separated from the primary conductor terminals (7) of the leadframe arrangement (6) by a spacing (D1 , D2, D3, D4) extending across a surface of the primary conductor module16. The current transducer according to claim 15 wherein the primary conductor module comprises an insulating layer (18) mounted on top of the primary conductor overmold, the insulating layer being made of a material having a higher electrical breakdown resistance than a material of the primary conductor overmold (16).

17. The current transducer according to claim 16 wherein the insulating layer is selected from a group of materials consisting of glass or polyimide.

18. The current transducer according to either of the two directly preceding claims wherein the insulating layer (18) is assembled on a top surface of the primary conductor overmold (16) with an insulating adhesive layer.

19. The current transducer according to any preceding claim 15-18 wherein the primary conductor (14) of the primary conductor module (5) comprises a recess (24) along the bridging portion (14c), the recess extending into the primary conductor from a mounting side (23).

20. The current transducer according to any preceding claim 15-19 wherein the first connection portion (14a) and second connection portion (14b) of the primary conductor (14) are connected to the respective primary conductor terminals (7a, 7b) by a solder connection.

21. The current transducer according to any preceding claim 15-20 wherein the magnetic field sensor die is surrounded on at least three edges by a spacing extending across a top wall of the primary conductor module to an edge of the primary conductor module.

22. The current transducer according to any preceding claim 15-21 wherein the primary conductor module comprises an overhang (22) such that the top surface of the primary conductor module has a larger surface area than a mounting surface area of the primary conductor module positioned against the primary conductor terminal (7).

23. The current transducer according to the preceding claim wherein the overhang (22) is formed by the primary conductor overmold (16) or by an insulating layer (18) mounted on a top wall of the primary conductor overmold.

24. The current transducer according to any preceding claim 15-23 wherein the magnetic field sensor die comprises at least two magnetic field sensing portions (3a, 3b) spaced apart overhead the bridging portion (14c) of the primary conductor (14) for measuring a differential magnetic field or an in-plane magnetic field gradient.

25. The current transducer according to any preceding claim 15-24 wherein the sensor die comprises two or at least two tunnel magneto resistance (TMR) portions.

26. The current transducer according to any preceding claim 15-25 wherein the interconnects (9) between the magnetic field sensor die (2) and the secondary conductor terminals (8) consist of bond wires.

27. A method of manufacturing a current transducer according to any of the preceding claims 15-26, comprising the steps of- stamping and forming out of a single strip of sheet metal the leadframe arrangement comprising the primary conductor terminals and the secondary terminals (8),- separately forming the primary conductor module (5) including stamping and forming the primary conductor (14) out of a second sheet of metal, overmolding the primary conductor (14) with an insulating material, bonding an insulating layer (18) on a top surface of the primary conductor overmold (16), bonding the magnetic field sensor die (2) on top of the insulating layer (18),- mounting and interconnecting the primary conductor module on top of the primary conductor terminal (7) of the leadframe arrangement (6), interconnecting the secondary terminals (8) to connection terminals of the magnetic field sensor die,-overmolding the leadframe arrangement (6), primary conductor module (5) and magnetic field sensor die with an insulating polymer material.

28. The method of the preceding claim wherein the primary conductor overmold is overmolded by injection molding of a thermosetting or thermoplastic polymer.

29. The method of either of the two directly preceding claims wherein the primary conductor module is mounted on the primary conductor terminals by soldering the primary conductor pads of the primary conductor module to the primary conductor terminals (7a, 7b) of the leadframe arrangement (6).

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