Magnetic sensor and magnetic detection method

Abstract

The present invention provides a magnetic sensor and a magnetic detection method, which can improve the transient response characteristics of the measured magnetic field. The magnetic sensor (100) of the present invention includes: a Hall integrated circuit (120) having a Hall element (121) formed on the surface; and a lead frame (110) supporting the Hall integrated circuit (120), wherein the lead frame (110) includes: a first region (111a) arranged near the Hall element (121) and utilizing a first eddy current (i11b) generated by applying a measured magnetic field (H) a ), to generate the first magnetic field (h a );And the second region (111b), the second region (111c), and the first region (111a) are separated and configured, and the second eddy current (i b ), the second eddy current (i c ), to generate the first magnetic field (h a ) to eliminate the second magnetic field (h b +h c ).

Description

Technical Field

[0001] The invention relates to a magnetic sensor and a magnetic detection method. Background Art

[0002] Conventionally, many magnetic sensors have been developed in which a semiconductor device (semiconductor chip) having a directional magnetic detection element such as a Hall element formed on its surface is supported by a conductive lead frame and then sealed with resin to cover the lead frame.

[0003] In a magnetic sensor of this structure, when the intensity or applied direction of the magnetic field being measured changes, eddy currents are generated in the lead frame. These eddy currents generate a magnetic field in a direction that cancels the measured magnetic field with a magnitude corresponding to the intensity or rate of change of the measured magnetic field. This leads to a problem of deteriorating the transient response characteristics to the measured magnetic field.

[0004] In this regard, for example, a magnetic sensor is disclosed that has a structure in which a notch is provided in a lead frame so that the lead frame does not exist near a magnetic detection element (see, for example, Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Publication No. 2009-544149 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] In one aspect, an object is to provide a magnetic sensor capable of improving transient response characteristics to a magnetic field to be measured.

[0010] Technical means to solve the problem

[0011] In one embodiment, the magnetic sensor comprises:

[0012] A semiconductor device having a magnetic detection element formed on a surface thereof; and

[0013] a conductive substrate supporting the semiconductor device, and

[0014] The conductive substrate comprises:

[0015] a first region disposed near the magnetic detection element and generating a first magnetic field by using a first eddy current generated by application of a magnetic field to be measured; and

[0016] The second region is disposed apart from the first region and generates a second magnetic field having a strength that cancels the first magnetic field by utilizing a second eddy current generated by application of the magnetic field to be measured.

[0017] In the magnetic sensor according to one embodiment of the present invention, the conductive substrate is in the form of a flat plate.

[0018] In the magnetic sensor according to one embodiment of the present invention, at least one of a notch and a slit is provided between the first region and the second region.

[0019] In the magnetic sensor according to one embodiment of the present invention, the area of ​​the first region is smaller than the area of ​​the second region.

[0020] In a magnetic sensor according to one embodiment of the present invention, the magnetic detection element has directionality, the first region is arranged in a magnetically sensitive direction where the sensitivity of the magnetic detection element is maximum, from the position of the magnetic detection element, and the second region is not arranged in the magnetically sensitive direction, from the position of the magnetic detection element.

[0021] In the magnetic sensor according to one embodiment of the present invention, the magnetic detection element is any one of a Hall element, a magnetoresistive element, and a magneto-impedance element.

[0022] In the magnetic sensor according to one embodiment of the present invention, the through-hole is provided in the first region so as to include a portion closest to the magnetic detection element.

[0023] In the magnetic sensor according to one embodiment of the present invention, the conductive base has a line-symmetrical shape when the conductive base is viewed in plan, and the magnetic detection element is arranged on an axis of symmetry of the line-symmetrical shape.

[0024] In the magnetic sensor according to one embodiment of the present invention, the conductive base has a point-symmetrical shape when the conductive base is viewed in plan, and the magnetic detection element is arranged at a center point of the point-symmetry.

[0025] In one embodiment, a magnetic detection method uses a magnetic sensor, wherein the magnetic sensor includes:

[0026] A semiconductor device having a magnetic detection element formed on a surface thereof; and

[0027] a conductive substrate supporting the semiconductor device, and

[0028] The conductive substrate comprises:

[0029] a first region disposed near the magnetic detection element; and

[0030] The second area is configured to be separated from the first area,

[0031] The magnetic detection method comprises:

[0032] generating a first magnetic field in the first region by utilizing a first eddy current generated by applying the magnetic field to be measured; and

[0033] In the second region, a second magnetic field having a strength that cancels the first magnetic field is generated by utilizing a second eddy current generated by application of the magnetic field to be measured.

[0034] Effects of the Invention

[0035] In one aspect, a magnetic sensor capable of improving transient response characteristics to a magnetic field to be measured can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a perspective view showing the magnetic sensor according to the first embodiment.

[0037] Figure 2 It is a perspective plan view showing the magnetic sensor according to the first embodiment.

[0038] Figure 3 This is a perspective side view showing the magnetic sensor according to the first embodiment.

[0039] Figure 4 This is an explanatory diagram showing the flow of eddy current generated on the die pad in the magnetic sensor according to the first embodiment.

[0040] Figure 5 This is a side view showing a penetration of a magnetic field generated in a first region in the magnetic sensor according to the first embodiment.

[0041] Figure 6 This is a side view showing a penetration of a magnetic field generated in the second region in the magnetic sensor according to the first embodiment.

[0042] Figure 7 This is an explanatory diagram showing a magnetic field caused by eddy currents generated in respective regions of the die pad in the magnetic sensor according to the first embodiment.

[0043] Figure 8 It is an explanatory diagram showing an analysis model of the magnetic sensor according to the first embodiment.

[0044] Figure 9 This is an explanatory diagram showing an analysis model of a conventional magnetic sensor.

[0045] Figure 10 It means using Figure 8 and Figure 9Graphs showing calculation results of transient response characteristics obtained using various analysis models are shown.

[0046] Figure 11 This is a perspective side view showing the magnetic sensor according to the first embodiment.

[0047] Figure 12 This is a perspective side view when the semiconductor chip is thinned and low-profiled in the magnetic sensor according to the first embodiment.

[0048] Figure 13 This is an explanatory diagram showing a magnetic field applied to a magnetic detection element when the height of a semiconductor chip is reduced in the magnetic sensor according to the first embodiment.

[0049] Figure 14 It is a perspective plan view showing Modification 1 of the magnetic sensor according to the first embodiment.

[0050] Figure 15 It is a perspective plan view showing a second modification of the magnetic sensor according to the first embodiment.

[0051] Figure 16 It is a perspective plan view showing a magnetic sensor according to a second embodiment.

[0052] Figure 17 This is a perspective side view of the magnetic sensor according to the second embodiment.

[0053] Figure 18 It means in Figure 17 Graph showing the calculation results of the eddy current density generated in the AA section.

[0054] Figure 19 It means in Figure 17 Graph showing calculation results of the magnetic field of the eddy current generated in the AA section.

[0055] Figure 20 It is a perspective plan view showing a first modification of the magnetic sensor according to the second embodiment.

[0056] Explanation of symbols

[0057] 100: Magnetic sensor

[0058] 110: Lead frame

[0059] 111, 113-117: Die pad (conductive substrate)

[0060] 111a, 113a, 115a, 116a, 117a: First area

[0061] 111b, 111c, 113b, 113c, 115b, 116b, 116c, 117b, 117c: Second area

[0062] 112: Lead

[0063] 120: Hall IC (semiconductor device)

[0064] 121: Hall element (magnetic detection element)

[0065] 130: Sealing resin

[0066] 140: Conductive adhesive

[0067] 150: Au wire

[0068] i a : Eddy current (generated in the first region)

[0069] i b 、i c : Eddy current (generated in the second region)

[0070] H: Magnetic field to be measured

[0071] h a : The first magnetic field

[0072] h b :Using eddy current i b The magnetic field generated

[0073] h c :Using eddy current i c The magnetic field generated

[0074] h b +h c : Second magnetic field

[0075] P: Through hole

[0076] s: magnetic sensing direction

[0077] t: thickness

[0078] L, L1, W, W1, W2, W3, W4: Width

[0079] X, Y, Z: direction DETAILED DESCRIPTION

[0080] A magnetic sensor according to one embodiment of the present invention includes a semiconductor device having a magnetic detection element formed on its surface, and a conductive substrate supporting the semiconductor device. The conductive substrate includes a first region disposed near the magnetic detection element and generating a first magnetic field using first eddy currents generated by application of a magnetic field to be measured; and a second region disposed separately from the first region and generating a second magnetic field having a strength sufficient to cancel the first magnetic field using second eddy currents generated by application of the magnetic field to be measured.

[0081] Furthermore, the so-called regional separation of the conductive substrate means that independent regions are formed to such an extent that an eddy current generated in one region does not flow into another region.

[0082] The second magnetic field having a strength that cancels the first magnetic field means a magnetic field that suppresses the influence of the first magnetic field at the position where the magnetic detection element is arranged.

[0083] The magnetic sensor according to one embodiment of the present invention is based on the following findings.

[0084] When a magnetic field to be measured is applied to the lead frame, eddy currents are generated according to the strength or rate of change of the magnetic field to be measured. The eddy currents generated in the lead frame generate a magnetic field in a direction opposite to the direction of application of the magnetic field to be measured.

[0085] In this regard, the lead frame of the conventional magnetic sensor described in Patent Document 1 is divided into two by a central notch, with a Hall element positioned above the notch. Therefore, when a magnetic field to be measured is applied to the entire magnetic field sensor from below the notch, the magnetic field passing through the notch itself does not generate eddy currents in the lead frame, enabling highly accurate detection.

[0086] However, if the magnetic field to be measured is applied to the lead frame separated by the cut, the magnetic field caused by the eddy currents generated in the separated lead frames is applied to the magnetic detection element in a direction that strengthens the magnetic field to be measured. Therefore, overshoot is likely to occur in the output of the magnetic sensor, and there is a problem of deterioration of transient response characteristics. Figures 8 to 10 The calculation results of the transient response characteristics obtained by each analysis model shown in FIG will be described.

[0087] Therefore, a magnetic sensor according to one embodiment of the present invention includes a first region and a second region on a conductive substrate supporting a semiconductor device having a magnetic detection element formed on its surface. The first region is positioned near the magnetic detection element and generates a first magnetic field by utilizing first eddy currents generated by application of a magnetic field to be measured. The second region is positioned separately from the first region and generates a second magnetic field of sufficient strength to cancel the first magnetic field by utilizing second eddy currents generated by application of a magnetic field to be measured.

[0088] Thus, when a magnetic field to be measured is applied, the magnetic sensor according to one embodiment of the present invention cancels the first magnetic field generated in the first region in a direction opposite to that of the magnetic field to be measured by the second magnetic field generated in the second region, thereby improving transient response characteristics.

[0089] In addition, a magnetic detection method of one embodiment of the present invention is a magnetic detection method using a magnetic sensor, wherein the magnetic sensor includes: a semiconductor device having a magnetic detection element formed on a surface; and a conductive substrate supporting the semiconductor device, the conductive substrate including: a first region arranged near the magnetic detection element, and a second region arranged separately from the first region, and in the first region, a first eddy current generated by applying a measured magnetic field is used to generate a first magnetic field, and in the second region, a second eddy current generated by applying a measured magnetic field is used to generate a second magnetic field with a strength that eliminates the first magnetic field.

[0090] Thus, the magnetic detection method according to one embodiment of the present invention can improve the transient response characteristics to the magnetic field to be measured, similarly to the magnetic sensor according to one embodiment of the present invention.

[0091] The magnetic detection method according to one embodiment of the present invention can be suitably performed using the magnetic sensor according to one embodiment of the present invention. Therefore, the magnetic detection method according to one embodiment of the present invention will be described below along with the operation of the magnetic sensor according to one embodiment of the present invention.

[0092] Next, one embodiment of the magnetic sensor of the present invention will be described with reference to the drawings.

[0093] Furthermore, the dimensions, materials, shapes, relative arrangements, and the like of the components illustrated in the embodiments may be appropriately changed depending on the structure of the device to which the present invention is applied, various conditions, and the like.

[0094] In the drawings, the same components are denoted by the same reference numerals, and overlapping descriptions may be omitted.

[0095] In the drawings, the X, Y, and Z directions are orthogonal to each other. The direction including the X direction and the direction opposite to the X direction (-X direction) is referred to as the "X-axis direction," the direction including the Y direction and the direction opposite to the Y direction (-Y direction) is referred to as the "Y-axis direction," and the direction including the Z direction and the direction opposite to the Z direction (-Z direction) is referred to as the "Z-axis direction" (height direction, thickness direction).

[0096] Furthermore, the plane including the X-axis direction and the Y-axis direction is called the "XY plane", the plane including the X-axis direction and the Z-axis direction is called the "XZ plane", and the plane including the Y-axis direction and the Z-axis direction is called the "YZ plane".

[0097] (First embodiment)

[0098] Figure 1 It is a perspective view showing the magnetic sensor according to the first embodiment.

[0099] like Figure 1 As shown, the magnetic sensor 100 includes a lead frame 110 , a Hall integrated circuit (IC) 120 , and a sealing resin 130 .

[0100] The lead frame 110 includes a die pad 111 disposed in the center and various leads 112 disposed around the die pad 111. The lead frame 110 is formed by pressing a Cu alloy thin plate having a thickness of approximately 130 μm.

[0101] The die pad 111 , which is a conductive base, adheres and supports the Hall IC 120 with the conductive adhesive 140 , so that the portion where the Hall IC 120 is adhered is in a flat plate shape.

[0102] The Hall IC 120 is a chip-shaped semiconductor device with a Hall element 121, a magnetic detection element, formed near the center of the surface of a 150μm-thick semiconductor substrate. The Hall IC 120 includes circuitry to operate the Hall element 121 and outputs a voltage corresponding to the strength of the magnetic field being measured, detected by the Hall element 121.

[0103] In addition, various pads are formed on the surface of the Hall IC 120. These pads are electrically connected to the various leads 112 through Au wires 150 by wire bonding.

[0104] The sealing resin 130, specifically an insulating epoxy resin or the like, is cured to cover the die pad 111, a portion of the leads 112, the Hall IC 120, and the Au wires 150. The portions of the leads 112 not covered by the sealing resin 130 serve as external leads, used as power terminals, GND terminals, output terminals, function conversion terminals, and the like for the magnetic sensor 100.

[0105] Figure 2 It is a perspective plan view showing the magnetic sensor according to the first embodiment. Figure 2 , the positional relationship between the die pad 111 and the Hall element 121 arranged on the surface of the Hall IC 120 is mainly shown. Figure 2 In FIG. 1 , the dotted line indicates the outline of the Hall IC 120 mounted on the die pad 111 .

[0106] like Figure 2 As shown, the die pad 111 is divided into a first region 111a in the center and second regions 111b and 111c at its two ends by two cuts.

[0107] The Hall IC 120 is mounted such that the Hall element 121 is located in the center of the first region 111 a . That is, the die pad 111 is linearly symmetrical in plan view, and the Hall element 121 is arranged on the linearly symmetrical axis.

[0108] Figure 3 This is a perspective side view of the magnetic sensor according to the first embodiment, viewed in the +Y axis direction. Figure 2 FIG. 1 shows the die pad 111 and the Hall IC 120.

[0109] like Figure 3 As shown, the Hall IC 120 is mounted on the die pad 111 so that the Hall element 121 is located in the +Z-axis direction at the center of the first region 111a. Furthermore, the direction of highest detection sensitivity of the Hall element 121, namely the magnetic sensing direction s, lies in the +Z-axis direction. In other words, the Hall element 121 has directivity. From the position of the Hall element 121, the first region 111a is located in the magnetic sensing direction where the Hall element 121 has the highest sensitivity, while the second regions 111b and 111c are not located in the magnetic sensing direction from the position of the Hall element 121.

[0110] Here, if the measured magnetic field H is applied to the die pad 111 and the Hall IC 120 in the same direction of the +Z axis, then the first region 111a, the second region 111b, and the second region 111c of the die pad 111 are as follows: Figure 4 As shown, eddy currents are generated.

[0111] Figure 4 This is an explanatory diagram showing the flow of eddy current generated on the die pad in the magnetic sensor according to the first embodiment.

[0112] like Figure 4 As shown in FIG. 1 , if the magnetic field H to be measured is applied in the +Z axis direction in the same manner, an eddy current i is generated in the first region 111a at the center with a magnitude corresponding to the width W1 thereof. a , by the eddy current i a The magnetic field induced is generated in the -Z axis direction. In addition, in the second region 111b and the second region 111c on both sides, eddy currents i corresponding to the width W2 are generated. b , eddy current i c , by the eddy current i b , eddy current i c The induced magnetic fields are generated in the -Z axis direction.

[0113] Furthermore, since the first region 111 a and the second regions 111 b and 111 c are separated by two cutouts, eddy currents generated in the respective regions do not flow between the respective regions.

[0114] In this way, if Figure 5 As shown, the eddy current i generated in the first region 111a is used. a , the first magnetic field h a In the -Z axis direction, it is applied to the Hall element 121. Figure 6 As shown, the eddy current i generated in the second region 111b and the second region 111c is used. b , eddy current i c , and along the eddy current i b , eddy current i c The magnetic field h is generated in the direction of the magnetic field b , magnetic field h c , as the second magnetic field h of its synthetic magnetic field b +h c The voltage is applied to the Hall element 121 in the +Z-axis direction.

[0115] In addition, since the area of ​​the first region 111a is narrower than that of the second region 111b and the second region 111c, the eddy current i generated by the first region 111a is smaller. a As for the magnetic field caused, the synthetic magnetic field caused by the second region 111b and the second region 111c is stronger, but due to the positional relationship with the Hall element 121, the intensity of the magnetic field can be easily made equal at the position of the Hall element 121 and can be easily canceled.

[0116] In addition, in this embodiment, since the magnetic detection element is the Hall element 121, the Hall element 121 is set at a position where the second magnetic field h b +h c The Z-axis component of the first magnetic field h is eliminated a In addition, if the magnetic detection element does not have directivity, a second magnetic field h with the opposite direction and the same strength is used at the position of the magnetic detection element. b +h c To eliminate the first magnetic field h a .

[0117] In this embodiment, if Figure 7 As shown, if the measured magnetic field H is applied, the second magnetic field h generated in the second region 111b and the second region 111c at the position of the Hall element 121 is b +h c , to cancel the first magnetic field h generated in the first region 111a in the direction opposite to the direction of the measured magnetic field H a , thus improving the transient response characteristics.

[0118] In addition, when the die pad 111 is viewed from above, if the shape of the die pad 111 is linearly symmetrical and the center of the Hall element 121 is located on the axis of symmetry of the linear symmetry, the first magnetic field h a With respect to the Hall element 121, the second magnetic field h is formed as a composite magnetic field with only a -Z axis component. b +h c With respect to the Hall element 121, it becomes only the +Z axis direction component. Therefore, at the position of the Hall element 121, the second magnetic field h b +h c To eliminate the first magnetic field h a This is advantageous in that the design becomes easier.

[0119] In addition, methods for adjusting the intensity of the second magnetic field to an intensity that cancels the first magnetic field include, for example, adjusting the area or thickness of each region, the distance between the first region and the second region, etc. based on results obtained by commercially available numerical simulations.

[0120] Numerical simulation

[0121] Secondly, refer to Figures 8 to 10 , and the results calculated by numerical simulation using the finite element method are explained.

[0122] Figure 8 This is an explanatory diagram showing an analysis model of the magnetic sensor according to the first embodiment, and shows an analysis model of a die pad as an example.

[0123] The die pad analysis model had a planar outer shape of a rectangle with two cutouts. Dimensions were set as follows: thickness was 130 μm; and volume resistivity was 0.023 μΩm.

[0124] L: 1,700 μm (dimension of one side of the die pad)

[0125] L1: 200 μm (width of the portion connecting the first region and the second region)

[0126] W: 2,150μm (the other side of the die pad)

[0127] W1: 300 μm (corresponding to the size of one side of the first region)

[0128] W2: 675 μm (equivalent to the size of one side of each part of the second region)

[0129] W3: 250 μm (the size of the gap between the first region and the second region)

[0130] Furthermore, the probe position for calculating the magnetic field strength (corresponding to the position where the Hall element is arranged) is set 150 μm above the surface of the center of the die pad.

[0131] Figure 9 It is an explanatory diagram showing an analysis model of a conventional magnetic sensor, and shows an analysis model as a comparative example.

[0132] The comparative analysis model is identical to the example, except that the portion connecting the first and second regions remains and the portion corresponding to the first region is removed. Therefore, the dimension of the gap between the portions corresponding to the second region, W4, can be calculated using the following equation: W - W2 × 2, resulting in a value of 800 μm.

[0133] Figure 10 Is to use Figure 8 and Figure 9 In the graph of the calculation results of the transient response characteristics obtained by the analytical model shown, the vertical axis represents the magnetic field intensity (arbitrary unit: au) at the position of the Hall element, and the horizontal axis represents time (μsec). Figure 10 In FIG, the measured magnetic field applied to each analysis model is indicated by a dotted line, the calculation results of the embodiment are indicated by a bold line, and the calculation results of the comparative example are indicated by a thin line. In addition, the direction of application of the measured magnetic field is set to the +Z axis direction.

[0134] like Figure 10As shown, the magnetic field intensity at the probe position in the embodiment is less than 1 μsec, which is the rise time of the DC magnetic field to be measured, and the overshoot is relatively small, indicating that the probe follows the magnetic field to be measured.

[0135] It is believed that the reason is that Figure 7 As shown, by using the second magnetic field h b +h c To eliminate the first magnetic field h a , which can improve the transient response characteristics to the measured magnetic field H.

[0136] Back to Figure 10 In the comparative example, the magnetic field intensity at the probe position has a large overshoot below 1 μsec, indicating that it does not follow the magnetic field to be measured.

[0137] It is believed that the reason is that Figure 7 Only the second magnetic field h is generated b +h c , this second magnetic field h b +h c Since the voltage is superimposed in the direction of strengthening the magnetic field H to be measured, an overshoot occurs in the output, and the transient response characteristics to the magnetic field H to be measured are deteriorated.

[0138] [Regarding low-profile design]

[0139] Next, consider the case where a magnetic sensor is used as a current detector to detect the current flowing through a conductor. In this case, the magnetic sensor inserts into the gap of a cylindrical open magnetic core covering the conductor and measures the magnetic field generated by the current flowing through the conductor, thus functioning as a current detector. Therefore, the narrower the gap in the open magnetic core, the less magnetic flux leaks, enabling more accurate measurement of the magnetic field generated by the current. Therefore, a low-profile magnetic sensor is required.

[0140] Regarding this issue, the conventional magnetic sensor described in Patent Document 1 suffers from a problem where, when the semiconductor chip is thinned to achieve a low profile, the Hall element formed on the surface of the semiconductor chip comes close to the lead frame, causing the magnetic field generated by the eddy current to be detected in the direction of maximum sensitivity. This leads to a further increase in overshoot. This is specifically explained as follows.

[0141] Figure 11 This is a perspective side view of the magnetic sensor according to the first embodiment, viewed in the +X axis direction. Figure 1 When the picture.

[0142] like Figure 11 As shown in FIG. 1 , if the thickness of the Hall IC 120 is t, then if the thickness of the Hall IC 120 is reduced to t / 2 by adjusting the back grinding amount for low-profile design, the thickness becomes as follows: Figure 12At this time, Figure 13 As shown, since the Hall element 121 is close to the first region 111a, when the thickness of the Hall IC 120 is t, the first magnetic field h a In addition, if the Hall element 121 is close to the second region 111b and the second region 111c, the magnetic field h is greater than when the thickness of the Hall IC 120 is t. b , magnetic field h c The +Z axis direction components of the second magnetic field h b +h c Enhancement.

[0143] Therefore, even if the Hall IC 120 of the magnetic sensor 100 is made thinner for a lower profile, the first magnetic field h a and the second magnetic field h b +h c The second magnetic field h is also enhanced, so the second magnetic field h can be easily utilized by adjusting the size of the lead frame. b +h c To eliminate the first magnetic field h a .

[0144] On the other hand, in the conventional magnetic sensor described in Patent Document 1, if the thickness of the Hall IC 120 is set to t / 2, only the enhanced second magnetic field h b +h c Therefore, a larger overshoot is generated than when the thickness of the Hall IC 120 is t, which leads to a further deterioration of the transient response characteristics to the measured magnetic field H. In order to avoid the deterioration of the transient response characteristics, Figure 9 If the size W4 of the gap between the parts shown is increased, the rigidity of the lead frame or the bonding area between the semiconductor substrate and the lead frame is reduced, thereby reducing reliability.

[0145] Therefore, even if the Hall IC 120 is thinned for a lower profile, the magnetic sensor 100 can improve the transient response characteristics without reducing reliability, unlike conventional magnetic sensors that further deteriorate the transient response characteristics or reduce reliability to avoid such deterioration.

[0146] (Modification 1 of the first embodiment)

[0147] Figure 14 It is a perspective plan view showing Modification 1 of the magnetic sensor according to the first embodiment.

[0148] like Figure 14As shown, the die pad 113 in this first modification is not shaped so that the two cutouts are oriented in the same direction when viewed from above. Instead, the two cutouts are oriented in different directions, separating the first region 113a from the second region 113b and the second region 113c. That is, when viewing the die pad 113 from above, if the die pad 113 is arranged so that the shape is point-symmetrical and the center of the Hall element 121 is located at the center point of the point-symmetrical shape, then, similar to the above embodiment, the first magnetic field h a For the Hall element 121, the second magnetic field h is only the −Z-axis direction component and serves as the composite magnetic field. b +h c For the Hall element 121, it becomes only the +Z axis direction component. Therefore, at the position of the Hall element 121, the second magnetic field h b +h c To eliminate the first magnetic field h a The advantage is that the design becomes easier.

[0149] (Variation 2 of the First Embodiment)

[0150] Figure 15 It is a perspective plan view showing a second modification of the magnetic sensor according to the first embodiment.

[0151] The shape of the die pad when viewed from above may not be line symmetrical, for example, Figure 15 As shown, consider the case where the Hall element 121 is located toward the +X-axis side from the center of the Hall IC 120. In this case, the die pad 115 is separated by a single cutout into a first region 115a and a second region 115b, and the Hall IC 120 is mounted on the die pad 115 with the Hall IC 120 located at the center of the first region 115a. In this case, if a magnetic field to be measured is applied in the +Z-axis direction, the second magnetic field generated in the second region 115b at the position of the Hall element 121 can cancel the first magnetic field generated in the first region 115a in a direction opposite to the direction of the magnetic field to be measured.

[0152] (Second embodiment)

[0153] In the first embodiment, if the mounting position of the Hall IC relative to the die pad is inconsistent, the position of the Hall element will be inconsistent, resulting in changes in the strength of the first and second magnetic fields at that position. This makes it difficult to cancel the first magnetic field with high accuracy.

[0154] Therefore, in the second embodiment, if Figure 16 and Figure 17As shown, in the first embodiment, the through hole P is provided in the first region 116a of the die pad 116 so as to include the portion closest to the Hall element 121. The die pad 116 includes the first region 116a and the second regions 116b and 116c.

[0155] Thus, the eddy current density can be set to zero at the portion where the through-hole P is provided, and thus the peak of the magnetic field intensity generated by the eddy current can be suppressed and flattened.

[0156] Therefore, the magnetic sensor of the second embodiment provides a through hole in the first region near the Hall element, flattening the peak of the intensity distribution of the magnetic field generated by the eddy current in the first region. Consequently, even if the position of the Hall IC mounted on the die pad of the magnetic sensor of the second embodiment is inconsistent, the change in the magnetic field caused by the eddy current acting on the Hall element does not increase, thus minimizing inconsistencies in the transient response characteristics.

[0157] Specifically, as described below, the results of numerical simulations will be used for explanation.

[0158] Figure 18 It means in Figure 17 The graph showing the calculation results of the eddy current density generated on the AA line is obtained by numerical simulation using the two-dimensional finite element method. Figure 18 The vertical axis represents the eddy current density (arbitrary unit, Arbitrary Unit: au), and the horizontal axis represents the position in the X-axis direction (μm) with the center of the first region being 0. Figure 18 In the second embodiment, the use of Figure 17 The calculation results of the die pad analysis model are shown in bold, and the first embodiment for comparison is used. Figure 3 The calculation results in the die pad analysis model are shown with thin lines. In addition, the width of the first region is set to -300 μm to +300 μm, and the width of the through hole provided in the die pad in the second embodiment is set to -200 μm to +200 μm.

[0159] like Figure 18 As shown, no through hole is provided Figure 3 In the die pad, the eddy current density is negative at -300 μm on the X-axis and positive at +300 μm. This indicates that the direction of the eddy current at -300 μm is opposite to that at +300 μm. It can be seen that the eddy current density increases linearly from -300 μm to +300 μm.

[0160] In the case of a through hole Figure 17In the die pad of , it can be seen that the eddy current density becomes 0 at the location where the through hole is provided, that is, between the position of -200 μm and the position of +200 μm.

[0161] Figure 19 It means that Figure 17 The graph of the calculation results of the magnetic field caused by the eddy current generated by the AA line is Figure 18 The “eddy current density” on the vertical axis in is the result of calculation as “the intensity of the magnetic field caused by the eddy current”. Figure 19 In, with Figure 18 Likewise, the use of the second embodiment Figure 17 The calculation results of the die pad analysis model are shown in bold, and the first embodiment for comparison is used. Figure 3 The calculation results in the analysis model of the die pad are shown with thin lines. In addition, the setting values ​​of the through holes provided in the die pad in the second embodiment are also set to the same as Figure 18 same.

[0162] like Figure 19 As shown, it can be seen that the Figure 3 For the die seat, a through hole is provided. Figure 17 The magnetic field caused by the eddy current is weakened at the position of the grain seat near 0μm on the X axis. This is believed to be due to the Figure 18 As shown, Figure 17 In the die pad of , the eddy current density in the area where the through hole is set from -200 μm to +200 μm becomes 0. Therefore, it can be seen that the eddy current density is 0 when compared with the area where the through hole is not set. Figure 3 For the die seat, a through hole is provided. Figure 17 The die pad suppresses changes in the magnetic field at a position near 0 μm, resulting in a flat characteristic.

[0163] Therefore, if Figure 18 and Figure 19 As shown, the eddy current density can be set to zero in the area where the through-hole is provided in the die pad. This allows the peak of the magnetic field intensity generated by the eddy current to be suppressed and flattened. Consequently, in the magnetic sensor of the second embodiment, even if there are inconsistencies in the position of the Hall IC mounted on the die pad, changes in the magnetic field caused by the eddy current can be suppressed, and inconsistencies in the transient response characteristics are unlikely.

[0164] (Variation 1 of the Second Embodiment)

[0165] Figure 20 It is a perspective plan view showing a first modification of the magnetic sensor according to the second embodiment.

[0166] Figure 20 The die pad 117 shown in FIG. Figure 14The die pad 113 of the modified example 1 of the magnetic sensor of the first embodiment shown is provided with a through hole P. The die pad 117 includes a first region 117 a and second regions 117 b and 117 c.

[0167] In addition, in each example of the second embodiment, the shape of the through hole provided in the first region is set to be rectangular, but it is not limited to this. In addition, the structure and size of the through hole can also be appropriately selected according to the purpose.

[0168] As described above, a magnetic sensor according to one embodiment of the present invention includes: a semiconductor device having a magnetic detection element formed on its surface; and a conductive substrate supporting the semiconductor device, wherein the conductive substrate includes: a first region arranged near the magnetic detection element, for generating a first magnetic field by utilizing a first eddy current generated by applying a magnetic field to be measured; and a second region arranged separately from the first region, for generating a second magnetic field of a strength sufficient to cancel the first magnetic field by utilizing a second eddy current generated by applying a magnetic field to be measured.

[0169] Thus, the magnetic sensor according to one embodiment of the present invention can improve the transient response characteristics to the magnetic field to be measured.

[0170] Furthermore, in the aforementioned embodiments, Hall elements are used as magnetic detection elements, but this is not limiting. For example, magnetoresistive elements, magnetic impedance elements, or elements capable of detecting omnidirectional magnetism may be used. The thickness of the Hall IC or the die pad is not limited to those in the aforementioned embodiments and can be selected appropriately.

[0171] Furthermore, in each of the aforementioned embodiments, a notch is provided on one end of the conductive substrate in order to separate the first and second regions, but the present invention is not limited thereto. To control the flow of eddy currents between the regions, for example, notches may be provided from both ends, or one or more slits (long and narrow through-holes when viewed from above), grooves, or non-through-holes may be provided, or complete separation may be achieved.

[0172] Furthermore, in the above-described embodiments, the material of the die pad is described as a Cu alloy. However, the material is not limited to this as long as it generates eddy current when a magnetic field is applied.

[0173] Furthermore, in the aforementioned embodiments, the Hall IC is mounted on the die pad so that it is located at the center of the first region when viewed from above. However, this is not limiting as long as the magnetic field caused by eddy currents at the location of the Hall IC can be canceled. In other words, the embodiment is not limiting to the aforementioned embodiments; as long as the shape, structure, size, and material of the first and second regions of the conductive substrate can be appropriately selected to cancel the magnetic field caused by eddy currents at the location of the magnetic detection element, any configuration will suffice.

Claims

1. A magnetic sensor, characterized in that: include: A chip-shaped semiconductor device with a magnetic detection element formed on its surface; a conductive substrate supporting the semiconductor device; as well as The lead frame includes a die pad as the conductive substrate arranged in the center and a plurality of leads arranged around the die pad, and The conductive substrate comprises: A first region is disposed near the magnetic detection element and generates a first magnetic field by using a first eddy current generated by applying a magnetic field to be measured; as well as The second region is disposed apart from the first region and generates a second magnetic field having a strength that cancels the first magnetic field by utilizing a second eddy current generated by application of the magnetic field to be measured.

2. The magnetic sensor according to claim 1, wherein The conductive substrate is in a flat plate shape.

3. The magnetic sensor according to claim 1, wherein At least one of a cutout and a slit is provided between the first region and the second region.

4. The magnetic sensor according to claim 1, wherein The first region is narrower than the second region.

5. The magnetic sensor according to claim 1, wherein The magnetic detection element has directivity, The first region is arranged in a magnetic sensing direction where the sensitivity of the magnetic detection element is the highest, starting from the position of the magnetic detection element. The second region is not arranged in the magnetic sensitivity direction from the position of the magnetic detection element.

6. The magnetic sensor according to claim 5, wherein The magnetic detection element is any one of a Hall element, a magnetoresistive element, and a magneto-impedance element.

7. The magnetic sensor according to claim 1, wherein A through hole is provided in the first region so as to include a portion closest to the magnetic detection element.

8. The magnetic sensor according to any one of claims 1 to 7, characterized in that When the conductive base is viewed in plan, the conductive base has a line-symmetrical shape, and the magnetic detection element is arranged on the line-symmetrical axis.

9. The magnetic sensor according to any one of claims 1 to 7, characterized in that When the conductive base is viewed from above, the shape of the conductive base is point-symmetrical, and the magnetic detection element is arranged at a center point of the point-symmetry.

10. A magnetic detection method using a magnetic sensor, wherein the magnetic sensor comprises: A chip-shaped semiconductor device with a magnetic detection element formed on its surface; a conductive substrate supporting the semiconductor device; as well as The lead frame includes a die pad as the conductive substrate arranged in the center and a plurality of leads arranged around the die pad, and The conductive substrate comprises: a first region disposed near the magnetic detection element; as well as The second area is configured to be separated from the first area, The magnetic detection method is characterized in that generating a first magnetic field in the first region by utilizing a first eddy current generated by applying the magnetic field to be measured; and In the second region, a second magnetic field having a strength that cancels the first magnetic field is generated by utilizing a second eddy current generated by application of the magnetic field to be measured.

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