Magnetic sensor and method for manufacturing the same

Abstract

To reduce the gap between an element formation surface of a sensor chip and a magnetism collecting body as much as possible while increasing working efficiency during assembly, and control the size of the gap so that variations between products fall within a certain range.SOLUTION: A magnetic sensor 10 comprises: a sensor chip 20 that is mounted on a substrate 2 such that an element formation surface 20a becomes perpendicular to a surface of the substrate; and a magnetism collecting body 30 that is mounted on the substrate such that a surface 31 is opposite to the element formation surface 20a. The magnetism collecting body 30 has a surface 32 located on the opposite side of the surface 31, and both the surfaces 31 and 32 are flattened. This reduces the gap between the element formation surface 20a and the magnetism collecting body 30 and reduces variations between products. In addition, the flattening of the surface 32 eliminates directivity with respect to the sensor chip when the magnetism collecting body 30 is mounted on the substrate 2 and improves working efficiency during assembly.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a magnetic sensor and a method for manufacturing the same, and more particularly to a magnetic sensor including a sensor chip mounted on a surface of a substrate and a magnetic flux concentrator, and a method for manufacturing the same.

Background Art

[0002] Magnetic sensors are widely used in ammeters, magnetic encoders, and the like. A magnetic flux concentrator for collecting magnetic flux may be provided on a sensor chip for the purpose of increasing detection sensitivity in a magnetic sensor. For example, Patent Document 1 discloses a magnetic sensor including a sensor chip mounted on a substrate such that an element formation surface is perpendicular to the substrate, and a magnetic flux concentrator mounted on the substrate such that an end portion faces the element formation surface.

[0003] The magnetic sensor described in Patent Document 1 has an advantage that even when a long magnetic flux concentrator is used, the magnetic flux concentrator can be stably held on the substrate because the sensor chip is mounted on the substrate with the element formation surface lying flat at 90° with respect to the substrate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, if the processing accuracy of the magnetic flux concentrator is low, the element formation surface of the sensor chip and the magnetic flux concentrator may not be in complete contact, and a slight gap may occur between them. Since this gap significantly affects the detection sensitivity of the magnetic field, it is desirable that the gap be as small as possible, and it is also desirable to control the size of the gap so that the variation between products falls within a certain range.

[0006] In order to minimize the gap between the element formation surface of the sensor chip and the magnetic collector, and to control the size of the gap so that variations between products remain within a certain range, one possible method is to flatten the surface of the magnetic collector facing the element formation surface by grinding or polishing it.

[0007] However, when the magnetic collector is roughly rectangular in shape, flattening only the surface facing the element formation surface necessitates checking the orientation of the magnetic collector when mounting it on the substrate, which reduces work efficiency.

[0008] Therefore, the present invention aims to provide a magnetic sensor and a method for manufacturing the same that can control the size of the gap between the element formation surface of the sensor chip and the magnetic collector, while improving work efficiency during assembly, and minimizing the gap, and ensuring that variations between products remain within a certain range. [Means for solving the problem]

[0009] The magnetic sensor according to the present invention comprises a substrate, a sensor chip mounted on the surface of the substrate having an element-forming surface on which a magnetic sensing element is formed, such that the element-forming surface is perpendicular to the surface of the substrate, and a magnetic collector mounted on the surface of the substrate such that a first surface faces the element-forming surface of the sensor chip, wherein the magnetic collector has a second surface located on the opposite side of the first surface, and the first and second surfaces are flattened.

[0010] According to the present invention, since the flatness of the first surface of the magnetic collector is improved, it is possible to minimize the gap between the element formation surface of the sensor chip and the magnetic collector, and to control the size of the gap so that variations between products remain within a certain range. Moreover, since the second surface located on the opposite side of the first surface is also flattened, there is no directionality relative to the sensor chip when mounting the magnetic collector on the substrate. This also improves work efficiency during assembly.

[0011] In the present invention, the magnetic collector has a third surface facing the surface of the substrate, and the third surface may be flattened. As a result, the third surface of the magnetic collector adheres to the substrate with almost no gap, which reduces variations in the gap between the sensor chip element formation surface and the magnetic collector caused by variations in the gap between the substrate and the magnetic collector. Moreover, since the friction between the third surface of the magnetic collector and the substrate is reduced, it becomes easier to slide the magnetic collector on the substrate and bring it into contact with the sensor chip during assembly.

[0012] In the present invention, the magnetic collector has a fourth surface located opposite the third surface, and the third and fourth surfaces may be flattened. This eliminates the directionality relative to the substrate when mounting the magnetic collector on the substrate, thus improving work efficiency during assembly.

[0013] In the present invention, the magnetic collector has fifth and sixth surfaces perpendicular to the first to fourth surfaces, and the fifth and sixth surfaces may be flattened. This allows for improved assembly efficiency, even when the magnetic collector is mounted in a product where, for example, the fifth or sixth surface faces the substrate.

[0014] In the present invention, the flatness of the first to fourth surfaces may be higher than that of the fifth and sixth surfaces. This simplifies the process of planarizing the fifth and sixth surfaces.

[0015] In the present invention, the arithmetic mean waviness Wa of the first and second surfaces may be 0.1 μm or less. This significantly reduces the decrease in detection sensitivity caused by the gap between the element formation surface and the magnetic collector, and also significantly reduces the variation in detection sensitivity between products.

[0016] In the present invention, the magnetic collector may be made of ferrite material. Although ferrite material has low flatness in the as-cut state, the first and second surfaces can be flattened by grinding or polishing.

[0017] The method for manufacturing a magnetic sensor according to the present invention is characterized by comprising: a first step of cutting a magnetic collector from a block made of a magnetic material; a second step of flattening the first and second surfaces of the magnetic collector by grinding or polishing the first and second surfaces located on opposite sides of the magnetic collector; a third step of mounting a sensor chip on the surface of a substrate such that the element formation surface on which the magnetic sensing element is formed is perpendicular to the surface of the substrate; and a fourth step of mounting a magnetic collector on the surface of the substrate such that the first surface faces the element formation surface of the sensor chip.

[0018] According to the present invention, since the flatness of the first surface of the magnetic collector is improved, it is possible to minimize the gap between the element formation surface of the sensor chip and the magnetic collector, and to control the size of the gap so that variations between products remain within a certain range. Moreover, since the second surface located on the opposite side of the first surface is also flattened, there is no directionality relative to the sensor chip when mounting the magnetic collector on the substrate. This also improves work efficiency during assembly.

[0019] In the second step, the third surface, which is perpendicular to the first and second surfaces, is further flattened by grinding or polishing it, and in the fourth step, the magnet collector may be mounted on the surface of the substrate so that the third surface faces the surface of the substrate. As a result, the third surface of the magnet collector adheres to the substrate with almost no gap, which reduces the variation in the gap between the element formation surface of the sensor chip and the magnet collector caused by variations in the gaps between the magnet collectors on the substrate. Moreover, since the friction between the third surface of the magnet collector and the substrate is reduced, when the fourth step is performed while biasing the magnet collector so that the first surface of the magnet collector is pressed against the element formation surface of the sensor chip, the magnet collector becomes more slippery on the substrate. [Effects of the Invention]

[0020] Thus, according to the present invention, while enhancing the working efficiency during assembly, the gap between the element formation surface of the sensor chip and the magnetic flux concentrator can be made as small as possible, and the size of the gap can be controlled so that the variation among products falls within a certain range.

Brief Description of the Drawings

[0021] [Figure 1] FIG. 1 is a schematic perspective view showing the appearance of the magnetic sensor 10 according to a preferred embodiment of the present invention. [Figure 2] FIG. 2 is a schematic perspective view for explaining the structure of the element formation surface 20a of the sensor chip 20. [Figure 3] FIG. 3 is a circuit diagram for explaining the connection relationship of the magnetosensitive elements R1 to R4. [Figure 4] FIG. 4 is a schematic perspective view for explaining the structure of the magnetic flux concentrator 30. [Figure 5] FIGS. 5(a) to (c) are schematic diagrams for explaining the application positions of the adhesives 71 to 73. [Figure 6] FIG. 6 is a graph showing the relationship between the arithmetic mean waviness Wa of the surface 3 of the magnetic flux concentrator and the gap G generated between the element formation surface 20a and the magnetic flux concentrator 30. [Figure 7] FIG. 7 is a graph showing the relationship between the gap G and the sensitivity of the magnetic sensor 10. [[ID=

[28] ] [Figure 8] FIG. 8 is a flowchart for explaining the manufacturing process of the magnetic sensor 10. [Figure 9] FIG. 9 is a schematic diagram for explaining a method of supplying and curing the adhesive 71 while biasing the magnetic flux concentrator 30.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0023] FIG. 1 is a schematic perspective view showing the appearance of the magnetic sensor 10 according to a preferred embodiment of the present invention. [[ID=]45]

[0024] As shown in Figure 1, the magnetic sensor 10 according to this embodiment comprises a substrate 2 whose surface constitutes the xz plane, and a sensor chip 20 and magnetic collectors 30, 41, and 42 placed on the surface of the substrate 2. The sensor chip 20 has an element formation surface 20a that constitutes the xy plane, and one end of the magnetic collector 30 in the z direction faces the element formation surface 20a. The magnetic collectors 41 and 42 are provided on the back side of the sensor chip 20. The magnetic collectors 30, 41, and 42 are blocks made of a soft magnetic material with high magnetic permeability, such as ferrite.

[0025] As shown in Figure 1, in this embodiment, the sensor chip 20 is mounted such that the element formation surface 20a of the sensor chip 20 is perpendicular to the surface of the substrate 2. In other words, the sensor chip 20 is mounted at a 90° angle to the substrate 2. Therefore, even if the length of the magnetic collector 30 in the z direction is long, the magnetic collector 30 can be stably fixed to the substrate 2.

[0026] Figure 2 is a schematic perspective view illustrating the structure of the element formation surface 20a of the sensor chip 20.

[0027] As shown in Figure 2, the sensor chip 20 has a roughly rectangular parallelepiped shape, and four magnetic sensing elements R1 to R4 are formed on the element formation surface 20a that constitutes the xy plane. The magnetic sensing elements R1 to R4 are not particularly limited as long as they are elements whose characteristics change according to the direction or strength of the magnetic field, for example, magnetoresistive elements can be used. In the following description, we will explain using the case where the magnetic sensing elements R1 to R4 are magnetoresistive elements and have the same magnetization fixing direction as an example. Here, the positions of magnetic sensing elements R1 and R3 in the x direction are the same, and the positions of magnetic sensing elements R2 and R4 in the x direction are the same. Also, the positions of magnetic sensing elements R1 and R4 in the y direction are the same, and the positions of magnetic sensing elements R2 and R3 in the y direction are the same.

[0028] Magnetic layers 21 to 23 are formed on the element formation surface 20a of the sensor chip 20. Magnetic layer 21 is located approximately in the center of the element formation surface 20a in a plan view, and magnetic layers 22 and 23 are arranged on both sides of it in the x direction. Although not particularly limited, magnetic layers 21 to 23 may be films made of composite magnetic materials in which magnetic fillers are dispersed in a resin material, thin films or foils made of soft magnetic materials such as nickel or permalloy, or thin films or bulk sheets made of ferrite or the like. Magnetic sensing elements R1 and R3 are placed in the gap formed by magnetic layer 21 and magnetic layer 22, and magnetic sensing elements R2 and R4 are placed in the gap formed by magnetic layer 21 and magnetic layer 23.

[0029] The magnetic collector 30 is positioned between the magnetic sensing elements R1, R3 and R2, R4 in a plan view, i.e., from the z-direction, and has a rectangular parallelepiped shape with the z-direction as its longitudinal direction. The magnetic collector 30 collects the magnetic flux in the z-direction and splits it on both sides in the x-direction on the element forming surface 20a. The height of the magnetic collector 30 in the z-direction is not particularly limited, but increasing the height in the z-direction can improve the selectivity of the magnetic flux in the z-direction. In this embodiment, the width of the magnetic collector 30 in the y-direction is approximately the same as the width of the sensor chip 20 in the y-direction, but the present invention is not limited to this.

[0030] One side and half of the back surface of the sensor chip 20 are covered by the magnetic collector 41. Similarly, the other side and the remaining half of the back surface of the sensor chip 20 are covered by the magnetic collector 42. While the provision of magnetic collectors 41 and 42 is not essential in this invention, providing them makes it possible to further enhance the selectivity for magnetic flux in the z direction. The magnetic collectors 41 and 42 are extended in the z direction so that their position in the z direction exceeds the element formation surface 20a, and further have overhang portions OH1 and OH2 that are bent toward the element formation surface 20a from these extended portions.

[0031] In this configuration, when viewed from the z direction, the magnetic sensing elements R1 and R3 are located between the magnetic collector 30 and the overhang portion OH1 of the magnetic collector 41, and the magnetic sensing elements R2 and R4 are located between the magnetic collector 30 and the overhang portion OH2 of the magnetic collector 42. Therefore, the magnetic flux collected by the magnetic collector 30 is distributed almost equally to both sides in the x direction, and then drawn into the magnetic collectors 41 and 42 via the overhang portions OH1 and OH2. At this time, a portion of the magnetic flux passes through the magnetic sensing elements R1 to R4, so that magnetic sensing elements R1 and R3 and magnetic sensing elements R2 and R4 are given magnetic flux in opposite directions.

[0032] Figure 3 is a circuit diagram illustrating the connection relationships between the magnetic elements R1 to R4.

[0033] As shown in Figure 3, magnetic element R1 is connected between terminal electrodes 53 and 56, magnetic element R2 is connected between terminal electrodes 54 and 55, magnetic element R3 is connected between terminal electrodes 53 and 54, and magnetic element R4 is connected between terminal electrodes 55 and 56. Here, terminal electrode 56 is supplied with the power supply potential Vcc, and terminal electrode 54 is supplied with the ground potential GND. All magnetic elements R1 to R4 have the same magnetization fixing direction, and a difference arises between the resistance change of magnetic elements R1 and R3 located on one side of the magnetic collector 30 and the resistance change of magnetic elements R2 and R4 located on the other side of the magnetic collector 30. As a result, magnetic elements R1 to R4 form a differential bridge circuit, and the change in electrical resistance of magnetic elements R1 to R4 according to the magnetic flux density appears at terminal electrodes 53 and 55.

[0034] The differential signals output from terminal electrodes 53 and 55 are input to a differential amplifier 61 located on or outside the substrate 2. The output signal from the differential amplifier 61 is fed back to terminal electrode 52. As shown in Figure 3, a compensation coil C is connected between terminal electrodes 51 and 52, thereby generating a magnetic field corresponding to the output signal of the differential amplifier 61. The compensation coil C can be integrated into the sensor chip 20. With this configuration, when a change in the electrical resistance of the magnetosensitive elements R1 to R4 corresponding to the magnetic flux density appears at terminal electrodes 53 and 55, a current corresponding to the magnetic flux density flows through the compensation coil C, generating a magnetic flux in the opposite direction. This cancels out the external magnetic flux. Then, by converting the current output from the differential amplifier 61 to a voltage using the detection circuit 62, it becomes possible to detect the strength of the external magnetic flux.

[0035] Figure 4 is a schematic perspective view illustrating the structure of the magnetic collector 30.

[0036] As shown in Figure 4, the magnetic collector 30 is a roughly rectangular parallelepiped having six surfaces 31 to 36. Of these, surface 31 is the xy plane and, when mounted, faces the element formation surface 20a of the sensor chip 20. Surface 33 is the xz plane and, when mounted, faces the surface of the substrate 2. Surface 32 is the xy plane located on the opposite side of surface 31. Surface 34 is the xz plane located on the opposite side of surface 33. Surfaces 35 and 36 are yz planes located on opposite sides of each other.

[0037] In this embodiment, at least the surfaces 31 and 32 of the magnetic collector 30 are flattened. This is the result of grinding or polishing the surfaces 31 and 32 of the magnetic collector 30, as will be described later. As a result, when the magnetic collector 30 is mounted on the substrate 2, the surface 31 adheres to the element formation surface 20a of the sensor chip 20 with almost no gap, thereby suppressing the decrease in detection sensitivity caused by the gap between the element formation surface 20a and the magnetic collector 30, and reducing the variation in detection sensitivity between products. Specifically, it is preferable to set the arithmetic mean waviness Wa of the surfaces 31 and 32 (as defined in JIS B 0601:2013) to 0.1 μm or less. If the arithmetic mean waviness Wa of the surface 31 is 0.1 μm or less, the decrease in detection sensitivity caused by the gap between the element formation surface 20a and the magnetic collector 30 can be significantly reduced, and the variation in detection sensitivity between products can be significantly reduced. While the surface properties of the opposite surface 32 do not affect the characteristics, it becomes possible to mount the magnetic collector 30 on the substrate 2 such that surface 32 faces the element formation surface 20a instead of surface 31. In other words, since the magnetic collector 30 does not have a z-direction, assembly work efficiency can be improved.

[0038] Furthermore, it is preferable that not only the surfaces 31 and 32 of the magnetic collector 30, but also the surface 33 is flattened. When the surface 33 is flattened, when the magnetic collector 30 is mounted on the substrate 2, the surface 33 adheres to the surface of the substrate 2 with almost no gap. As a result, the angle between the surface 31 and the surface 33 approaches 90°, which reduces variations in the gap between the element formation surface 20a of the sensor chip 20 and the magnetic collector 30. Moreover, since the friction between the surface 33 of the magnetic collector 30 and the substrate 2 is reduced, it becomes easier to slide the magnetic collector 30 on the substrate 2 and bring it into contact with the sensor chip 20 during assembly. The arithmetic mean waviness Wa of the surface 33 may be the same as that of the surfaces 31 and 32, or it may be larger than that of the surfaces 31 and 32.

[0039] Furthermore, it is preferable that not only surfaces 31-33 of the magnetic collector 30, but also surface 34, be flattened. Although the surface properties of surface 34 do not affect the characteristics, flattening both surfaces 33 and 34 makes it possible to mount the magnetic collector 30 on the substrate 2 such that surface 34 faces the substrate 2 instead of surface 33. In other words, the magnetic collector 30 has no directionality in the y-direction, which improves work efficiency during assembly.

[0040] Furthermore, it is preferable that not only surfaces 31-34 of the magnetic collector 30, but also surfaces 35 and 36 are flattened. Although the surface properties of surfaces 35 and 36 do not affect the characteristics, even when the magnetic collector 30 is mounted in a product where surfaces 35 and 36 face the substrate 2, assembly work efficiency can be improved. The arithmetic mean waviness Wa of surfaces 35 and 36 may be the same as that of surfaces 31-34, or it may be greater than that of surfaces 31-34. In the latter case, the work of flattening surfaces 35 and 36 can be simplified.

[0041] As shown in Figure 5, adhesives 71 to 73 can be used to fix the magnetic collector 30. In the example shown in Figure 5(a), adhesive 71 is applied to the surface 34 of the magnetic collector 30 and the upper surface (xz plane) 20b of the sensor chip 20, thereby fixing the relative positional relationship between the sensor chip 20 and the magnetic collector 30. The surface 34 of the magnetic collector 30 may be rougher than surfaces 31 and 32. This allows for increased adhesive strength from the adhesive 71 compared to the case where the surface 34 of the magnetic collector 30 has the same flatness as surfaces 31 and 32. Furthermore, if the adhesive 71 seeps between the surface 31 of the magnetic collector 30 and the element forming surface 20a, the gap between the two may widen. However, in this embodiment, since the flatness of the surface 31 of the magnetic collector 30 is increased, seepage of the adhesive 71 due to surface tension is unlikely to occur.

[0042] Furthermore, in the example shown in Figure 5(b), adhesive 72 is applied across the surface 32 of the magnetic collector 30 and the surface of the substrate 2, thereby fixing the relative positional relationship between the substrate 2 and the magnetic collector 30.

[0043] Furthermore, in the example shown in Figure 5(c), adhesive 73 is applied to both the surfaces 35 and 36 of the magnetic collector 30 and the surface of the substrate 2, thereby fixing the relative positional relationship between the substrate 2 and the magnetic collector 30. The surfaces 35 and 36 of the magnetic collector 30 may be rougher than the surfaces 31 and 32. This allows for increased adhesive strength by the adhesive 73 compared to the case where the surfaces 35 and 36 of the magnetic collector 30 have the same flatness as the surfaces 31 and 32.

[0044] However, in this invention, it is not essential to use all of the adhesives 71 to 73, and some of the adhesives, such as adhesive 73, may be omitted.

[0045] Figure 6 is a graph showing the relationship between the arithmetic mean undulation Wa of the surface 31 of the magnetic collector 30 and the gap G that occurs between the element formation surface 20a and the magnetic collector 30.

[0046] As shown in Figure 6, in multiple samples where the arithmetic mean waviness Wa of the surface 31 is 0.5 μm, the measured value of the gap G varies greatly between approximately 20 μm and approximately 100 μm. The value of the gap G and its variation decrease as the arithmetic mean waviness Wa of the surface 31 decreases. In multiple samples where Wa is 0.3 μm, the measured value of the gap G is approximately 10 μm to approximately 40 μm (variation of approximately 30 μm). In multiple samples where Wa is 0.2 μm, the measured value of the gap G is approximately 0 μm to approximately 30 μm (variation of approximately 30 μm). In multiple samples where Wa is 0.1 μm, the measured value of the gap G is approximately 0 μm to approximately 10 μm (variation of approximately 10 μm). Thus, if Wa is 0.1 μm, not only is the absolute value of the gap G reduced, but the variation of the gap G can also be significantly suppressed. The smaller the arithmetic mean waviness Wa of the surface 31, the better the performance obtained. However, depending on the material properties and polishing method of the magnetic collector 30, it is practically difficult to reduce the arithmetic mean waviness Wa to less than 0.01 μm. Considering this point, a realistic value of Wa is 0.01 μm or more and 0.1 μm or less, preferably 0.03 μm or more and 0.05 μm or less.

[0047] Figure 7 is a graph showing the relationship between the gap G and the sensitivity of the magnetic sensor 10.

[0048] As shown in Figure 7, although the sensitivity of the magnetic sensor 10 is not uniquely determined by the gap G, a clear tendency for sensitivity to improve as the gap G narrows can be observed. In other words, the smaller the arithmetic mean waviness Wa of the surface 31, the better the sensitivity of the magnetic sensor 10. Furthermore, by flattening the surface 31 so that the arithmetic mean waviness Wa is 0.1 μm or less, high sensitivity can be obtained, and sensitivity variability can be significantly suppressed.

[0049] Next, a description will be given of how to manufacture the magnetic sensor 10 according to this embodiment.

[0050] Figure 8 is a flowchart illustrating the manufacturing process of the magnetic sensor 10 according to this embodiment.

[0051] First, a roughly rectangular magnetizing body 30 is cut out from a block made of a magnetic material such as ferrite (step S11). Then, the flatness of at least the surfaces 31 and 32 of the magnetizing body 30 is increased by grinding or polishing them (step S12). Immediately after cutting out the magnetizing body 30, the flatness of each surface 31 to 36 is low. However, grinding or polishing the surfaces 31 and 32 of the magnetizing body 30 increases the flatness of the surfaces 31 and 32. In step S12, the surfaces 33 and 34 may also be flattened by grinding or polishing, or all surfaces 31 to 36 may be flattened by grinding or polishing. If surface 33 is flattened, the angle between surface 31 and surface 33 will approach 90°.

[0052] Meanwhile, in parallel with the processing of the magnetic collector 30, the sensor chip 20 is mounted so that the element formation surface 20a is perpendicular to the substrate 2 (step S21). Then, the processed magnetic collector 30 is mounted on the surface of the substrate 2 (step S22). The magnetic collector 30 is mounted so that surface 33 faces the surface of the substrate 2 and surface 31 faces the element formation surface 20a of the sensor chip 20. As described above, since surface 31 of the magnetic collector 30 has high flatness, surface 31 of the magnetic collector 30 can be brought into close contact with the element formation surface 20a of the sensor chip 20 with almost no gap. When mounting the magnetic collector 30, it is not necessary to check the orientation of the magnetic collector 30 in the z direction, and surface 32 may be brought into close contact with the element formation surface 20a instead of surface 31.

[0053] Next, the magnetic collector 30 is fixed by supplying and curing adhesives 71-73 (step S23). At this time, it is preferable to supply and cure the adhesive while biasing the magnetic collector 30 so that the surface 31 of the magnetic collector 30 is properly pressed against the element forming surface 20a of the sensor chip 20. For example, as shown in Figure 9, it is preferable to supply the adhesive 71 from the dispenser 70 while biasing the magnetic collector 30 in the -z direction from the surface 32 side with a biasing jig 81 after placing the magnetic collector 30 on the substrate 2. At this time, it is preferable to support the back side of the sensor chip 20 with a fixing jig 82 so that the sensor chip 20 does not move or fall over in the -z direction. By supplying and curing the adhesive 71 using such jigs 81 and 82, the surface 31 of the magnetic collector 30 is kept in proper contact with the element formation surface 20a of the sensor chip 20, and the seepage of the adhesive 71 between the surface 31 of the magnetic collector 30 and the element formation surface 20a of the sensor chip 20 is prevented. Furthermore, if the surface 33 of the magnetic collector 30 is also flattened, the friction between the magnetic collector 30 and the substrate 2 is reduced, making it easier to slide the magnetic collector 30 on the substrate 2 to bring it into contact with the sensor chip 20.

[0054] The supply and curing of adhesives 72 and 73 can be done in the same manner, by fixing them in place using jigs 81 and 82.

[0055] As described above, the magnetic sensor 10 according to this embodiment has improved flatness of the surfaces 31 and 32 of the magnetic collector 30, so that the surface 31 of the magnetic collector 30 can be brought into close contact with the element formation surface 20a of the sensor chip 20 with almost no gaps. In addition, the seepage of the adhesive 71 between the surface 32 of the magnetic collector 30 and the element formation surface 20a of the sensor chip 20 is less likely to occur. Furthermore, since the magnetic collector 30 does not have a directionality in the z direction, the work of checking the direction of the magnetic collector 30 in the z direction is unnecessary, and work efficiency is also improved.

[0056] Although preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention, and these modifications are also included within the scope of the present invention. [Explanation of symbols]

[0057] 2 circuit boards 10 Magnetic Sensors 20 sensor chips 20a Element formation surface 20b Top surface of the sensor chip 21~23 Magnetic layer 30,41,42 Magnetic collector 31-36 Surface of the magnetic material 51~56 Terminal electrode 61 Differential Amplifier 62 Detection Circuit 70 Dispensers 71-73 Adhesive 81. Biasing jig 82 Fixing fixtures C Compensation coil OH1, OH2 Overhang Section R1~R4 Magnetic element

Claims

1. circuit board and A sensor chip having an element formation surface on which a magnetic element is formed, and mounted on the surface of the substrate such that the element formation surface is perpendicular to the surface of the substrate, The substrate comprises a magnetic collector mounted on the surface such that the first surface faces the element forming surface of the sensor chip, The magnetic collector is a substantially rectangular parallelepiped having a second surface located opposite the first surface, a third surface perpendicular to the first and second surfaces and facing the surface of the substrate, a fourth surface located opposite the third surface, and fifth and sixth surfaces perpendicular to the first to fourth surfaces. The first and second surfaces of the magnetic collector, the third and fourth surfaces of the magnetic collector, and the fifth and sixth surfaces of the magnetic collector have different planar shapes from each other. A magnetic sensor characterized in that the first and second surfaces are planar, thereby the flatness of the first and second surfaces is higher than the flatness of the third and fourth surfaces, and the flatness of the third and fourth surfaces is higher than the flatness of the fifth and sixth surfaces.

2. The magnetic sensor according to claim 1, characterized in that the arithmetic mean waviness Wa of the first and second surfaces is 0.1 μm or less.

3. The magnetic sensor according to claim 1 or 2, characterized in that the magnetic collecting element is made of a ferrite material.

4. The first step is to cut out a roughly rectangular magnetizing body from a block made of magnetic material, A second step involves grinding or polishing the first and second surfaces located on opposite sides of the magnetic collector to flatten the first and second surfaces, A third step is to mount the sensor chip on the surface of the substrate such that the element formation surface on which the magnetic element is formed is perpendicular to the surface of the substrate, The process includes a fourth step of mounting the magnetic collector on the surface of the substrate such that the first surface faces the element forming surface of the sensor chip, and the third surface, which is orthogonal to the first and second surfaces, faces the surface of the substrate, The magnetic collector has a fourth surface located opposite to the third surface, and fifth and sixth surfaces perpendicular to the first to fourth surfaces. The first and second surfaces of the magnetic collector, the third and fourth surfaces of the magnetic collector, and the fifth and sixth surfaces of the magnetic collector have different planar shapes from each other. A method for manufacturing a magnetic sensor, characterized in that, in the second step, the first to fourth surfaces are ground or polished such that the flatness of the first and second surfaces is higher than the flatness of the third and fourth surfaces, and the flatness of the third and fourth surfaces is higher than the flatness of the fifth and sixth surfaces.

5. The method for manufacturing a magnetic sensor according to claim 4, characterized in that the fourth step is performed while biasing the magnetic collector so that the first surface of the magnetic collector is pressed against the element forming surface of the sensor chip.

Images