JP2018036237A - Electric current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric current sensor that can be easily reduced in size without sacrificing its voltage resistance.SOLUTION: An electric current sensor is equipped with a primary conductor that is penetrated by an aperture from the top face to the bottom face and in which the measured current flows, a lead frame electrically separated from the primary conductor and having a part overlapping the aperture of the primary conductor, and a magnetism sensor that is arranged in a position overlapping the aperture of the primary conductor on the lead frame and detects the measured current. The electric current sensor may further have a signal processing chip that is arranged on the lead frame and processes signals outputted by the magnetism sensor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a current sensor.

Conventionally, a current sensor using a magnetic sensor such as a Hall element or a magnetoresistive element is known (see, for example, Patent Documents 1 and 2).
Patent Document 1 Japanese Patent Application Laid-Open No. 2005-283451 Patent Document 2 International Publication No. 2016/056135

  The current sensor is preferably downsized while ensuring the withstand voltage between the primary conductor through which the current to be measured flows and the magnetic sensor.

  In one aspect of the invention, a current sensor is provided. The current sensor may include a primary conductor in which an opening penetrating from the upper surface to the lower surface is formed and the current to be measured flows. The current sensor may include a lead frame that is provided so as to be electrically separated from the primary conductor and has a portion overlapping the opening of the primary conductor. The current sensor may be provided on the lead frame at a position overlapping with the opening of the primary conductor, and may include a magnetic sensor that detects the current to be measured.

  The current sensor may include a signal processing chip that is provided on the lead frame and processes a signal output from the magnetic sensor. The signal processing chip may be arranged so that at least a part of the signal processing chip overlaps with the primary conductor.

  The signal processing chip and the magnetic sensor may be arranged to overlap at least partially. The entire magnetic sensor may be disposed so as to overlap the signal processing chip. A magnetic sensor may be formed in the signal processing chip.

  The current sensor may include a wire that connects the magnetic sensor and the signal processing chip without straddling the primary conductor. A wire may be arrange | positioned in the position which the whole overlaps with an opening part. A part of the signal processing chip may be arranged so as to overlap the opening. The signal processing chip may have a pad connected to the wire in a portion overlapping with the opening.

  The magnetic sensor may be a Hall element that detects a longitudinal magnetic field in a direction perpendicular to the top surface of the lead frame provided with the magnetic sensor. The magnetic sensitive surface of the Hall element may be disposed between the upper surface and the lower surface of the primary conductor. The magnetic sensitive surface of the Hall element may be disposed at the center of the upper surface and the lower surface of the primary conductor.

  The magnetic sensor may be a magnetoresistive element that detects a transverse magnetic field in a direction parallel to the top surface of the lead frame provided with the magnetic sensor. The magnetosensitive surface of the magnetoresistive element is disposed between a position t / 2 higher than the upper surface of the primary conductor and a position t / 2 lower than the lower surface of the primary conductor, where t is the depth of the opening. Good.

  The magnetosensitive element may be arranged at a position t / 4 lower than the upper surface of the primary conductor from a position t / 2 higher than the upper surface of the primary conductor. The magnetosensitive element may be disposed between a position t / 4 higher than the lower surface of the primary conductor and a position t / 2 lower than the lower surface of the primary conductor. The magnetosensitive surface of the magnetoresistive element may be disposed at the same height as the upper or lower surface of the primary conductor. The magnetosensitive surface of the magnetoresistive element may be arranged at the same height as the lower surface of the primary conductor facing the upper surface of the lead frame provided with the magnetic sensor.

  The lead frame may be provided with a slit at a position overlapping the magnetic sensor. The primary conductor may be provided with a slit between the end where the current to be measured is input and the opening.

  The above summary of the present invention does not enumerate all of the features of the present invention. A sub-combination of these feature groups can also be an invention.

It is a top view which shows the outline | summary of the current sensor 100 which concerns on the 1st Embodiment of this invention. It is a side view at the time of cut | disconnecting the current sensor in FIG. 1 by the AA line. 4 is a side view for explaining the positional relationship between a magnetic sensor 60 and an opening 12. FIG. It is a top view which shows the outline | summary of the current sensor 200 which concerns on the 2nd Embodiment of this invention. It is a side view at the time of cut | disconnecting the current sensor 200 in FIG. 4 by the BB line. FIG. 10 is a top view showing another example of the structure around the opening 12. 4 is a top view showing an example of a lead frame 30. FIG. 2 is a top view illustrating an example of a primary conductor 10. FIG. 5 is a diagram illustrating an example of a manufacturing process of the primary conductor 10 and the lead frame 30. FIG.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

(First embodiment)
FIG. 1 is a top view showing an outline of a current sensor 100 according to a first embodiment of the present invention. FIG. 2 is a side view of the current sensor in FIG. 1 taken along line AA. The current sensor 100 includes a primary conductor 10, a lead frame 30, and a magnetic sensor 60. The current sensor 100 of this example further includes a sealing portion 70 that seals the primary conductor 10, the lead frame 30, and the magnetic sensor 60. The sealing portion 70 is made of an insulating material such as resin and is formed so as to cover the periphery of the primary conductor 10, the lead frame 30, and the magnetic sensor 60.

Primary conductor 10 is formed of a conductive material such as metal, flows the current to be measured I _P. The primary conductor 10 in this example has two end portions exposed from the sealing portion 70. A measured current I _P is input from one end, and a measured current I _P is output from the other end. The sealing part 70 of this example has a rectangular parallelepiped shape, and the two ends of the primary conductor 10 are exposed on the same surface of the sealing part 70. The primary conductor 10 of this example has a U shape in the top view. However, the shape of the primary conductor 10 is not limited to the shape shown in FIG. The two ends of the primary conductor 10 may be exposed on different surfaces of the sealing portion 70.

  The primary conductor 10 has an opening 12 penetrating from the upper surface to the lower surface. The primary conductor 10 of this example has a plate shape, and two main surfaces of the plate shape correspond to the upper surface and the lower surface. In this example, the entire opening portion 12 is disposed inside the sealing portion 70. 1 shows the upper surface of the primary conductor 10, the direction perpendicular to the upper surface of the primary conductor 10 is the Z-axis direction, the direction perpendicular to the surface where the primary conductor 10 is exposed in the sealing portion 70 is the X-axis direction, and X A direction perpendicular to both the axial direction and the Z-axis direction is taken as a Y-axis direction. The XY plane is parallel to the upper surface of the primary conductor 10.

  The opening 12 is surrounded by the primary conductor 10 in all directions on the XY plane. That is, the opening 12 is a closed region on the XY plane. The primary conductor 10 forms one current path upstream from the opening 12, forms a current path branched into two at the opening 12, and forms one current path downstream from the opening 12. To do.

  The lead frame 30 is made of a conductive material such as metal and is provided so as to be electrically separated from the primary conductor 10. The material of the lead frame 30 may be the same as the material of the primary conductor 10. The lead frame 30 and the primary conductor 10 are insulated by the sealing portion 70. At least a part of the lead frame 30 is provided at a position overlapping the opening 12 of the primary conductor 10 when viewed from the Z-axis direction. In FIG. 1, the outer shape of the lead frame 30 that overlaps the primary conductor 10 is indicated by a broken line. The lead frame 30 of this example has at least one end portion exposed from the sealing portion 70.

  As shown in FIG. 2, the primary conductor 10 has a bent portion 14 bent in the Z-axis direction inside the sealing portion 70. Further, the lead frame 30 has a bent portion 32 that is bent to the opposite side to the primary conductor 10 in the Z-axis direction. The bent portion 32 is disposed inside the sealing portion 70. The current sensor 100 of the present example is configured such that the primary conductor 10 exposed to the outside of the sealing portion 70 and the end portions of the lead frame 30 have the same height in the Z-axis direction, and the primary conductor 10 and the lead inside the sealing portion 70. The frames 30 are overlapped.

The magnetic sensor 60 is provided on the lead frame 30 at a position overlapping the opening 12 of the primary conductor 10 when viewed from the Z-axis direction. However, the magnetic sensor 60 is not in contact with the primary conductor 10. The magnetic sensor 60 may be arranged so that the entirety overlaps the opening 12 when viewed from the Z-axis direction. The magnetic sensor 60 of this example is disposed on the surface of the lead frame 30 that faces the opening 12. The magnetic sensor 60, by detecting the magnetic field generated by the current to be measured I _P, detects the current to be measured I _P. The magnetic sensor 60 has a Hall element or a magnetoresistive element. The magnetic sensor 60 may be formed on a semiconductor substrate such as GaAs or silicon. A plurality of magnetic sensors 60 may be provided on the lead frame 30.

  In the current sensor 100 of this example, the magnetic sensor 60 is placed on the lead frame 30. For this reason, it is not necessary to provide an insulating sheet or the like on which the magnetic sensor 60 is placed. Generally, when a magnetic sensor is disposed in a region sandwiched between primary conductors, an insulating sheet is pasted from the lower surface of the primary conductor to the lower surface of the primary conductor that faces the region. A magnetic sensor is placed on an insulating sheet attached between primary conductors. In this case, the insulating sheet forms a continuous creeping surface between the magnetic sensor and the primary conductor. Therefore, in order to ensure a certain withstand voltage, it is necessary to ensure the distance between the magnetic sensor and the primary conductor. For this reason, it is difficult to achieve both miniaturization of the current sensor and maintenance of the withstand voltage.

  Furthermore, since the magnetic sensor is mounted on the insulating sheet, the heat dissipation is poor, and the magnetic sensor sensitivity of the magnetic sensor is reduced by increasing the distance between the magnetic sensor and the primary conductor. In addition, as a method of not forming the creepage surface, a method of raising the primary conductor by providing a step, attaching an insulating sheet to the lead frame, and placing a magnetic sensor on the insulating sheet can be considered, but the magnetic sensor is directly mounted on the lead frame. Heat dissipation is poor compared to the case of mounting.

  On the other hand, in the current sensor 100, there is no continuous creeping surface between the primary conductor 10, the lead frame 30 and the magnetic sensor 60. Further, a resin or the like can be filled between the primary conductor 10 and the lead frame 30 and the magnetic sensor 60. For this reason, it is easy to achieve both size reduction of the current sensor 100 and maintenance of the withstand voltage.

  The current sensor 100 of this example further includes a signal processing chip 50 that is provided on the lead frame 30 and processes a signal output from the magnetic sensor 60. The signal processing chip 50 is an integrated circuit formed on a semiconductor substrate such as silicon. The signal processing chip 50 may supply a signal or electric power for operating the magnetic sensor 60. Further, the value of the current flowing through the primary conductor 10 may be calculated by correcting or calculating the signal output from the magnetic sensor 60. In FIG. 1, the outline of the signal processing chip 50 that overlaps the primary conductor 10 is indicated by a broken line.

  The signal processing chip 50 of this example is arranged so that at least a part thereof overlaps with the primary conductor 10 when viewed from the Z-axis direction. In the signal processing chip 50, more than half of the area viewed from the Z-axis direction may overlap with the primary conductor 10. By arranging the signal processing chip 50 so as to overlap the primary conductor 10, the current sensor 100 can be further reduced in size. Further, since the magnetic sensor 60 and the signal processing chip 50 are provided on the same lead frame 30, the temperature difference between the magnetic sensor 60 and the signal processing chip 50 can be reduced. The signal processing chip 50 may include a temperature detection unit that detects temperature. The signal processing chip 50 may correct the operation of the magnetic sensor 60 or the output signal of the magnetic sensor 60 based on the detected temperature. By reducing the temperature difference between the signal processing chip 50 and the magnetic sensor 60, the accuracy of the correction can be improved.

  The current sensor 100 of this example further includes a conductive wire 64 that connects the magnetic sensor 60 and the signal processing chip 50 without straddling the primary conductor 10. The wire 64 connects the pad 62 of the magnetic sensor 60 and the pad 52 of the signal processing chip 50. In FIG. 1, two pads 62 are schematically shown for one magnetic sensor 60, but the magnetic sensor 60 may have more pads 62. Each pad 62 is connected to any pad 52 of the signal processing chip 50.

The wire 64 may be disposed at a position where the entire wire 64 overlaps the opening 12 as viewed from the Z-axis direction. In this case, a part of the signal processing chip 50 is disposed so as to overlap the opening 12 as viewed from the Z-axis direction. Further, the pad 52 is disposed at a position overlapping the opening 12 when viewed from the Z-axis direction. With such a configuration, the wire 64 can be shortened. Therefore, to the signal transmitting wire 64, it is possible to reduce the influence of noise due to the current to be measured I _P. As shown in FIG. 2, the upper end of the wire 64 in the Z-axis direction may be disposed below the upper end of the opening 12.

  The signal processing chip 50 has one or more pads 34 in a region that does not overlap the primary conductor 10 when viewed from the Z-axis direction. At least one pad 34 may be connected to the lead frame 30 by a conductive wire 36. Another pad 34 may be connected to the lead frame 40 by a wire 36. The current sensor 100 of this example includes one or more lead frames 40 provided separately from the lead frame 30 on which the magnetic sensor 60 is placed. A signal is transmitted between an external circuit and the signal processing chip 50 via the lead frame 40.

  FIG. 3 is a side view for explaining the positional relationship between the magnetic sensor 60 and the opening 12. The magnetic sensor 60 has a magnetosensitive surface 66. The magnetic sensitive surface 66 in this example is the upper surface of the magnetic sensor 60. The surface on which the magnetic sensor 60 is placed in the lead frame 30 is referred to as an upper surface 31. Further, in the vicinity of the opening 12, the surface on the lead frame 30 side of the primary conductor 10 is a lower surface 18, and the opposite surface is an upper surface 16. The depth of the opening 12 in the Z-axis direction is t. The magnetic sensor 60 of this example is a magnetoresistive element that detects a transverse magnetic field in the Y-axis direction parallel to the upper surface 31 of the lead frame 30.

The magnetosensitive surface 66 of the magnetic sensor 60 is disposed between a position ΔZ1 that is t / 2 higher than the upper surface 16 of the primary conductor 10 and a position ΔZ2 that is t / 2 lower than the lower surface 18 of the primary conductor 10 in the Z-axis direction. It is preferred that Among these, since the magnitude of the transverse magnetic field is small in the central portion (near t / 2) of the thickness of the primary conductor 10, the upper surface of the primary conductor 10 from the position ΔZ <b> 1 higher than the upper surface 16 of the primary conductor 10 by t / 2. It is arranged between a position ΔZ3 that is lower than t / 4 by 18 or a position ΔZ4 that is higher by t / 4 than the lower surface 16 of the primary conductor 10 and a position ΔZ2 that is t / 2 lower than the lower surface 18 of the primary conductor 10. Is more preferable. By placing the sensitive surface 66 of the magnetic sensor 60 in the range, the magnetic field resulting from the current to be measured I _P flowing bypassing the both sides of the opening 12 can be detected accurately relatively.

  The magnetic sensitive surface 66 of the magnetic sensor 60 is preferably arranged at the same height as the upper surface 16 or the lower surface 18 of the primary conductor 10 in the Z-axis direction. In a magnetoresistive element that detects a transverse magnetic field, the sensitivity to the transverse magnetic field can be maximized when the magnetosensitive surface 66 is disposed in the same plane as the surface of the primary conductor 10 through which the current to be measured flows. When the magnetosensitive surface 66 is disposed in the same plane as the surface of the primary conductor 10 through which the current to be measured flows, there may be an error of about t / 10 in the Z-axis direction.

  Further, it is more preferable that the magnetosensitive surface 66 of the magnetic sensor 60 is disposed at the same height as the lower surface 18 of the primary conductor 10 in the Z-axis direction. Thereby, the spatial distance between the primary conductor 10, the lead frame 30, and the signal processing chip 50 can be increased while maximizing the magnetic field sensitivity. For this reason, a proof pressure can be improved. Further, the entire wire 64 can be easily disposed inside the opening 12.

(Second Embodiment)
FIG. 4 is a top view showing an outline of a current sensor 200 according to the second embodiment of the present invention. The signal processing chip 50 and the magnetic sensor 68 of this example are disposed so as to overlap at least partially in the Y-axis direction. The magnetic sensor 68 in FIG. 4 corresponds to the magnetic sensor 68 shown in FIGS.

  The signal processing chip 50 of this example is provided on the upper surface of the lead frame 30. The magnetic sensor 68 is provided on the upper surface of the lead frame 30. In this case, the entire magnetic sensor 68 is disposed so as to overlap the signal processing chip 50. The magnetic sensor 68 may be flip-chip connected to the signal processing chip 50. By arranging the magnetic sensor 68 on the signal processing chip 50, the size of the current sensor 200 in the XY plane can be further reduced.

  Further, the magnetic sensor 68 may be formed inside the signal processing chip 50. For example, the magnetic sensor 68 may be integrated on a semiconductor substrate on which the signal processing chip 50 is formed. Even with such a configuration, the size of the current sensor 200 can be reduced.

Moreover, the current sensor 200 of this example is different from the current sensor 100 in the position of the opening 12. In the current sensor 100 shown in FIG. 1, the opening 12 is formed in the region where the current to be measured I _P flowing in the X-axis direction, the current sensor 200, the current to be measured I _P in the Y-axis direction An opening 12 is formed in the flowing region. Opening 12, between the two ends of the primary conductor 10 may be formed in the middle of the current path to be measured current I _P flows. In the current sensor 100 in which the magnetic sensor 60 and the signal processing chip 50 are not overlapped, the opening 12 may be provided at a position as shown in FIG. 4. In the current sensor 200 in which the magnetic sensor 68 and the signal processing chip 50 are overlapped, You may provide the opening part 12 in a position as shown in FIG.

  The plurality of magnetic sensors 68 may be arranged at different positions in the direction in which the current to be measured flows on both sides of the opening 12 (in this example, the Y-axis direction). The plurality of magnetic sensors 68 may be arranged at different positions in a direction perpendicular to the direction in which the current to be measured flows (X-axis direction in this example).

  FIG. 5 is a side view of the current sensor 200 in FIG. 4 taken along the line BB. The magnetic sensor 68 in this example is a Hall element that detects a longitudinal magnetic field in a direction perpendicular to the upper surface 31 of the lead frame 30.

  In this example, the magnetosensitive surface 66 of the magnetic sensor 68 is disposed between the upper surface 16 and the lower surface 18 around the opening 12 of the primary conductor 10. By arranging the magnetosensitive surface 66 of the Hall element in the range, the longitudinal magnetic field can be detected with high sensitivity. The magnetic sensitive surface 66 is preferably disposed at the center of the upper surface 16 and the lower surface 18 of the primary conductor 10. The center of the primary conductor 10 in the thickness direction has the highest magnetic flux density in the vertical direction. For this reason, the detection sensitivity of the longitudinal magnetic field can be maximized. When the magnetosensitive surface 66 is arranged at the center of the upper surface 16 and the lower surface 18 of the primary conductor 10, an error of about t / 10 may be provided in the Z-axis direction. t indicates the thickness of the primary conductor 10.

  The magnetic sensor 68 and the signal processing chip 50 do not have to be stacked. However, by placing the magnetic sensor 68 on the upper surface 51 of the signal processing chip 50, the length of the wire connecting the signal between the magnetic sensor 68 and the signal processing chip 50 can be shortened. The influence of noise received from the current to be measured can be reduced, and the accuracy of wire bonding can be improved. Also in the example shown in FIG. 3, the magnetic sensor 60 and the signal processing chip 50 may be stacked.

FIG. 6 is a top view showing another example of the structure around the opening 12. The current sensor of this example includes a magnetic sensor 80. The magnetic sensor 80 includes three magnetoresistive elements 82-1 and 82 that detect a transverse magnetic field in a direction (X-axis direction in this example) perpendicular to the direction in which the current I _P to be measured flows (Y-axis direction in this example). -2, 82-3. A plurality of magnetoresistive elements 82 are arranged in the direction perpendicular to the direction in which the measured current I _P flows (X-axis direction in this example). In the X-axis direction, the distance between the magnetoresistive element 82-1 and the primary conductor 10 is preferably equal to the distance between the magnetoresistive element 82-3 and the primary conductor 10. The magnetoresistive element 82-2 is disposed at the center between the magnetoresistive element 82-1 and the magnetoresistive element 82-3 in the X-axis direction.

The signal processing chip 50 may detect a difference R1-R2 between the resistance value R1 of the magnetoresistive element 82-1 and the resistance value R2 of the magnetoresistive element 82-2. Further, the difference R3-R2 between the resistance value R3 in the magnetoresistive element 82-3 and the resistance value R2 in the magnetoresistive element 82-2 may be detected. The signal processing chip 50, based on the sum of the difference (R1-R2) + (R3 -R2), may calculate the current value of the current to be measured _{I P.} By such processing, it becomes possible to reduce the effect of external magnetic field can be calculated accurately the current value of the current to be measured I _P.

Incidentally current sensor in the vicinity of the magnetic sensor 80, by flowing a feedback current so as to cancel the magnetic field from the current to be measured I _P, even when measuring the current value of the feedback current when the magnetic field to be detected is zero Good. For example, the signal processing chip 50 may control the current value of the feedback current so that the calculated resistance value (R1-R2) + (R3-R2) becomes zero. The wiring through which the feedback current flows is preferably arranged near the magnetoresistive element 82 rather than the primary conductor 10.

The opening 12 may have a rectangular shape on the XY plane. However, it is preferable that the corner 13-1 on the upstream side of the current I _{P to} be measured out of the rectangular corner is curved. Similarly, the corner 13-2 on the downstream side is also preferably curved. Such a shape, it is possible to suppress the current to be measured I _P is when flowing branches on either side of the opening 12, the current at the corners of the opening 12 is concentrated.

  FIG. 7 is a top view showing an example of the lead frame 30. In FIG. 7, the positions facing the opening 12 and the magnetic sensor 68 are indicated by broken lines. The lead frame 30 of this example is provided with a slit 33 at a position overlapping the magnetic sensor 68. The slit 33 is formed to penetrate from the upper surface to the lower surface of the lead frame 30.

  The slit 33 is preferably formed so as to overlap at least the center of the magnetic sensitive surface of the magnetic sensor 68. The length of the slit 33 (in this example, the length in the Y-axis direction) may be larger than the width of the magnetic sensor 68 (in this example, the width in the Y-axis direction). Providing the slits 33 in the lead frame 30 can suppress the generation of eddy currents in the lead frame 30 and improve the responsiveness of the magnetic field generated by the current to be measured. The lead frame 30 of this example may be applied to any of the current sensors described in FIGS.

FIG. 8 is a top view illustrating an example of the primary conductor 10. The primary conductor 10 in this example has one or more slits 17. The slit 17 is formed to penetrate from the upper surface to the lower surface of the primary conductor 10. The at least one slit 17 is provided between the opening portion 12 and the end portion 15 of the primary conductor 10 on the side where the measured current _IP is input. Further, a slit 17 may be formed on the downstream side of the opening 12 in the current path.

The primary conductor 10 of this example extends in the X-axis positive direction from the end 15, bends and extends in the Y-axis direction inside the sealing portion 70, and further bends in the X-axis negative direction to seal the sealing portion Stretch to the outside of 70. The opening 12 is provided in a portion of the primary conductor 10 that extends in the Y-axis direction. That is, the primary conductor 10 has a U shape. Of the end side along the direction of flow to be measured current I _P of the primary conductor 10, the inner circumferential side of the U-shaped end side 11, the outer peripheral side and end side 19.

The current to be measured I _P is between the opening 12 and the end side 11, and flows to branch to the region between the opening 12 and the end side 19. It is preferable that the same amount of current flows on the end side 11 side and the end side 19 side. However, when the primary conductor 10 has a U-shape, a current easily flows in the region on the end 11 side.

  On the other hand, by forming at least one slit 17 on the end side 11 between the end 15 and the opening 12, the balance of the current flowing in the end 11 and end 19 can be adjusted. . The slit 17 may be formed in a portion of the end side 11 that extends in the Y-axis direction. The slit 17 may be formed by extending in the X axis positive direction from the end side 11.

  The length L in the X-axis direction of the slit 17 is adjusted so that the currents flowing on both sides of the opening 12 are balanced. As an example, the length L of the slit 17 may be smaller than the width W of the region between the end side 11 and the opening 12 or may be the same as the width W. As an example, the length L of the slit 17 is not less than half of the width W and not more than the width W.

  FIG. 9 is a diagram illustrating an example of the manufacturing process of the primary conductor 10 and the lead frame 30. As described above, the primary conductor 10 and the lead frame 30 have portions that bend in the Z-axis direction, such as the bent portion 14 and the bent portion 32. The bent portion can be formed by bending, half punching, etching, or the like. For example, as shown by the white arrow in FIG. 9, the bent portion is formed by pressing from the Z-axis direction.

  In the manufacturing process, the primary conductor 10 and the lead frame 30 have an extension portion 92 fixed to the fixing portion 90. Each fixing unit 90 is a frame whose positional relationship is fixed in advance. The primary conductor 10 and the lead frame 30 may be formed with a bent portion before being fixed to the fixing portion 90, or may be formed with being fixed to the fixing portion 90.

  First, the magnetic sensor 60, the signal processing chip 50, and the like are placed on the lead frame 30, and wire bonding is performed. Next, the primary conductor 10 and the lead frame 30 are fixed to the fixing portion 90, and the primary conductor 10 and the lead frame 30 are overlapped. Thereafter, in a state where the primary conductor 10 and the lead frame 30 are fixed to the fixing portion 90, the primary conductor 10 and the lead frame 30 are arranged inside a mold for forming the sealing portion 70, and the sealing portion 70 is formed. After forming the sealing part 70, the primary conductor 10 and the extension part 92 of the lead frame 30 are cut off. Thereby, a current sensor can be manufactured.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 ... Primary conductor, 11 ... End side, 12 ... Opening part, 13 ... Corner | angular part, 14 ... Bending part, 15 ... End part, 16 ... Upper surface, 17. ..Slit, 18 ... lower surface, 19 ... end side, 30 ... lead frame, 31 ... upper surface, 32 ... bent portion, 33 ... slit, 34 ... pad, 36 ... Wire, 40 ... Lead frame, 50 ... Signal processing chip, 51 ... Top surface, 52 ... Pad, 60 ... Magnetic sensor, 62 ... Pad, 64 ... Wire , 66 ... magnetosensitive surface, 68 ... magnetic sensor, 70 ... sealing part, 80 ... magnetic sensor, 82 ... magnetoresistive element, 90 ... fixing part, 92 ... Extension part, 100 ... current sensor, 200 ... current sensor

Claims (17)

A primary conductor in which an opening penetrating from the upper surface to the lower surface is formed, and a current to be measured flows;
A lead frame that is electrically separated from the primary conductor and has a portion overlapping the opening of the primary conductor;
A magnetic sensor provided on the lead frame at a position overlapping the opening of the primary conductor and detecting the current to be measured. The current sensor according to claim 1, further comprising a signal processing chip that is provided on the lead frame and processes a signal output from the magnetic sensor. The current sensor according to claim 2, wherein the signal processing chip is arranged so that at least a part of the signal processing chip overlaps the primary conductor. The current sensor according to claim 2, wherein the signal processing chip and the magnetic sensor are disposed so as to overlap at least partially. The current sensor according to claim 4, wherein the entire magnetic sensor is disposed so as to overlap the signal processing chip. The current sensor according to claim 2, wherein the magnetic sensor is formed in the signal processing chip. The current sensor according to any one of claims 2 to 6, further comprising a wire that connects the magnetic sensor and the signal processing chip without straddling the primary conductor. The current sensor according to claim 7, wherein the wire is disposed at a position where the entire wire overlaps the opening. A part of the signal processing chip is disposed so as to overlap the opening,
The current sensor according to claim 8, wherein the signal processing chip has a pad connected to the wire in a portion overlapping the opening. The magnetic sensor is a Hall element that detects a longitudinal magnetic field in a direction perpendicular to an upper surface of the lead frame provided with the magnetic sensor,
The current sensor according to any one of claims 1 to 9, wherein a magnetic sensitive surface of the Hall element is disposed between an upper surface and a lower surface of the primary conductor. The current sensor according to claim 10, wherein a magnetic sensitive surface of the Hall element is disposed at a center between the upper surface and the lower surface of the primary conductor. The magnetic sensor is a magnetoresistive element that detects a transverse magnetic field in a direction parallel to an upper surface of the lead frame provided with the magnetic sensor,
The magnetosensitive element has a magnetosensitive surface between a position t / 2 higher than the upper surface of the primary conductor and a position t / 2 lower than the lower surface of the primary conductor, where t is the depth of the opening. The current sensor according to claim 1, wherein the current sensor is arranged. A magnetosensitive surface of the magnetoresistive element is t / 2 higher than the upper surface of the primary conductor, t / 4 lower than the upper surface of the primary conductor, or t / 4 higher than the lower surface of the primary conductor. The current sensor according to claim 12, wherein the current sensor is disposed between a position and a position t / 2 lower than a lower surface of the primary conductor. The current sensor according to claim 12 or 13, wherein a magnetosensitive surface of the magnetoresistive element is disposed at the same height as an upper surface or a lower surface of the primary conductor. The current sensor according to claim 14, wherein a magnetosensitive surface of the magnetoresistive element is disposed at the same height as a lower surface of the primary conductor facing an upper surface of the lead frame on which the magnetic sensor is provided. The current sensor according to any one of claims 1 to 15, wherein the lead frame is provided with a slit at a position overlapping the magnetic sensor. The current sensor according to any one of claims 1 to 16, wherein the primary conductor is provided with a slit between an end portion to which the current to be measured is input and the opening.

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