WO2015107948A1

WO2015107948A1 - Magnetic sensor

Info

Publication number: WO2015107948A1
Application number: PCT/JP2015/050225
Authority: WO
Inventors: 清水　康弘; 川浪　崇
Original assignee: 株式会社村田製作所
Priority date: 2014-01-15
Filing date: 2015-01-07
Publication date: 2015-07-23
Also published as: JPWO2015107948A1

Abstract

　A magnetic sensor (10) is provided with a Wheatstone bridge circuit, a pair of power source lines (Lvcc, Lgnd), a pair of signal lines (Lin1, Lin2), a pair of power source pads (Pp1, Pp2), and a pair of output pads (Po1, Po2). The Wheatstone bridge circuit includes a pair of power source nodes (Np1, Np2), a pair of output nodes (No1, No2), and magnetic resistance elements (R1-R4). The pair of signal lines (Lin1, Lin2) are arranged in parallel.

Description

Magnetic sensor

The present invention relates to a magnetic sensor, for example, a magnetic sensor including a Wheatstone bridge circuit composed of four magnetoresistive elements.

A magnetic sensor having a Wheatstone bridge circuit composed of four magnetoresistive elements is well known. For example, Japanese Patent Laid-Open No. 8-242427 (Patent Document 1) discloses a configuration in which a signal between output terminals of a Wheatstone bridge circuit composed of four magnetoresistive elements is amplified by a differential amplifier circuit and output.

Japanese Patent Laid-Open No. 8-242427

A magnetic sensor having a Wheatstone bridge circuit composed of four magnetoresistive elements includes a pair of power supply terminals to which a power supply voltage is applied, and a pair of output terminals for converting a magnetic field change into a voltage and outputting the voltage. Have. The voltage (output voltage) at each output terminal is applied to the normal input terminal and the reverse input terminal of the differential amplifier circuit via a pair of signal wires. As a result, a closed loop is formed by the pair of signal wirings between the pair of output terminals of the Wheatstone bridge circuit and the input terminal pair (normal input terminal and inverted input terminal) of the differential amplifier circuit. It will be. The induced electromotive force induced in the closed loop due to the change in the magnetic field is superimposed as noise on the output voltage of the Wheatstone bridge circuit, that is, the input signal of the differential amplifier circuit, leading to a decrease in measurement accuracy of the magnetic sensor. Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

A magnetic sensor according to an aspect of the present invention includes a Wheatstone bridge circuit, a pair of power supply wirings, a pair of signal wirings, a pair of power supply pads, and a pair of output pads. The Wheatstone bridge circuit includes a pair of power supply nodes, a pair of output nodes, and first to fourth magnetoresistive elements. The first magnetoresistive element and the second magnetoresistive element are connected in series between the pair of power supply nodes via one of the pair of output nodes. The third magnetoresistive element and the fourth magnetoresistive element are connected in series between the pair of power supply nodes via the other of the pair of output nodes. The pair of power supply nodes are connected to the pair of power supply wirings through the pair of power supply pads. The pair of output nodes are connected to the pair of signal lines through the pair of output pads. The pair of signal wirings are arranged in parallel.

According to the present invention, it is possible to realize a magnetic sensor in which induced electromotive force generated in the magnetic sensor is suppressed and measurement accuracy is ensured.

1 is a circuit diagram illustrating a configuration of a magnetic sensor according to a first embodiment. FIG. 3 is a layout diagram of the magnetic sensor according to the first embodiment. 4 is a layout diagram of a magnetic sensor according to a comparative example of the magnetic sensor according to Embodiment 1. FIG. 6 is a layout diagram of a magnetic sensor according to a first modification of the first embodiment. FIG. 6 is a layout diagram of a magnetic sensor according to a second modification of the first embodiment. FIG. 6 is a layout diagram of a magnetic sensor according to a third modification of the first embodiment. FIG. 6 is a layout diagram of a magnetic sensor according to Embodiment 2. FIG. 6 is a layout diagram of a magnetic sensor according to a modification of the second embodiment. FIG. FIG. 6 is a layout diagram of a magnetic sensor according to a third embodiment. FIG. 10 is a layout diagram of a magnetic sensor according to a modification of the third embodiment. FIG. 3 is a circuit diagram illustrating a configuration of a current sensor circuit including the magnetic sensor according to the first embodiment. It is a perspective view explaining arrangement | positioning of the magnetic sensor which the current sensor circuit shown by FIG. 11 has.

Hereinafter, embodiments will be described with reference to the drawings. In the description of the embodiment, reference to the number, amount, and the like is not necessarily limited to the number, amount, and the like unless otherwise specified. In the drawings of the embodiments, the same reference numerals and reference numerals represent the same or corresponding parts. Further, in the description of the embodiments, the overlapping description may not be repeated for the portions with the same reference numerals and the like.

<Embodiment 1>
FIG. 1 is a circuit diagram showing a configuration of a magnetic sensor 10 according to the first embodiment.

Referring to FIG. 1, the magnetic sensor 10 includes magnetoresistive elements R1 to R4 constituting a Wheatstone bridge circuit. One end of each of magnetoresistive element R1 and magnetoresistive element R3 is connected to power supply node Np1. The other end of the magnetoresistive element R1 is connected to the output node No1. The other end of the magnetoresistive element R3 is connected to the output node No2. One end of each of magnetoresistive element R2 and magnetoresistive element R4 is connected to power supply node Np2. The other end of the magnetoresistive element R2 is connected to the output node No1. The other end of the magnetoresistive element R4 is connected to the output node No2.

The power supply node Np1 is connected to the power supply terminal VCC via the power supply wiring Lvcc. The power supply node Np2 is connected to the power supply terminal GND through the power supply wiring Lgnd. The power supply terminal VCC and the power supply terminal GND are connected to the positive electrode and the negative electrode of the DC power supply 3, respectively. Note that a constant current drive source may be used instead of the DC power supply 3. The output node No1 is connected to the positive input of the differential amplifier circuit 2 through the signal line Lin1. The output node No2 is connected to the negative input of the differential amplifier circuit 2 through the signal line Lin2. The differential amplifier circuit 2 amplifies the voltage between the output node No1 and the output node No2, and generates a magnetic sensor output Vo.

The magnetic sensor 10 and the differential amplifier circuit 2 constitute a magnetic sensor circuit 100. In the magnetic sensor circuit 100, as described above, the output node No1 of the Wheatstone bridge circuit is connected to the positive input of the differential amplifier circuit 2 via the signal wiring Lin1. The output node No2 of the Wheatstone bridge circuit is connected to the negative input of the differential amplifier circuit 2 through the signal line Lin2. As a result, a closed loop is formed by the signal wiring Lin1 and the signal wiring Lin2 between the output node No1 and the output node No2 of the Wheatstone bridge circuit and the positive input and the negative input of the differential amplifier circuit 2.

The time change of the magnetic flux density passing through the closed loop, that is, the induced electromotive force generated with the time change of the magnetic field is superimposed on the input signal of the differential amplifier circuit 2 as noise, and the measurement accuracy of the magnetic sensor 10 is lowered. The area of the closed loop mainly depends on the distance between the signal wiring Lin1 and the signal wiring Lin2. Therefore, in order to reduce the induced electromotive force, it is important to set the distance between the signal wiring Lin1 and the signal wiring Lin2 as short as possible.

FIG. 2 is a layout diagram of the magnetic sensor 10 according to the first embodiment. The magnetic sensor 10 has a configuration in which the magnetoresistive elements R1 to R4 shown in FIG. 1 are formed on a semiconductor substrate SUB. FIG. 2A is a plan view of the magnetic sensor 10. FIG. 2B is a cross-sectional view of the magnetic sensor 10 taken along the line IIb-IIb in FIG. A plan view of the magnetic sensor 10 will be described with reference to FIG.

(Configuration of magnetoresistive element and Wheatstone bridge circuit)
For example, each of the magnetoresistive elements R1 to R4 has a structure having a magnetic film Mg and a barber pole-shaped electrode formed on the magnetic film Mg. Examples of the magnetic film Mg include a film having a giant magnetoresistance (GMR) effect, a film having a tunnel magnetoresistance (TMR) effect, or an anisotropic magnetoresistance (AMR). ) A film having an effect is applied. A metal film such as aluminum is applied to the barber pole-shaped electrode. In the magnetoresistive elements R1 to R4, the region of the magnetic film Mg in which the barber pole-shaped electrode is not formed corresponds to a configuration electrically connected in series by the barber pole-shaped electrode. The surfaces of the magnetoresistive elements R1 to R4 are not shown, but are protected by a protective film, a silicone potting material, or a resin potting material.

As shown in FIG. 2A, a specific direction parallel to the paper surface is defined as the X direction, a direction parallel to the paper surface and orthogonal to the X direction is defined as the Y direction, and a direction orthogonal to each of the X direction and the Y direction is defined as Z. The direction. A plane parallel to the surface of the semiconductor substrate SUB is defined as an XY plane. Here, as the magnetic sensor 10, an example in which the short side direction of each of the magnetoresistive elements R1 to R4 is arranged in the X direction and the long side direction is arranged in the Y direction is shown. In this case, the magnetosensitive elements R1 to R4 are set in the X direction, and the magnetic bias direction is set in the Y direction.

One end of the magnetoresistive element R1, one end of the magnetoresistive element R3, and the power supply pad Pp1 are connected to the power supply node Np1 through the metal wiring ML. One end of the magnetoresistive element R2, one end of the magnetoresistive element R4, and the power supply pad Pp2 are connected to the power supply node Np2 through the metal wiring ML. The other end of the magnetoresistive element R1, the other end of the magnetoresistive element R2, and the output pad Po1 are connected to the output node No1 via the metal wiring ML. The other end of the magnetoresistive element R3, the other end of the magnetoresistive element R4, and the output pad Po2 are connected to the output node No2 via the metal wiring ML.

(Bridge circuit internal area)
As described above, the magnetoresistive element R1 and the magnetoresistive element R2 are connected in series between the power supply node Np1 and the power supply node Np2 via the output node No1 and the metal wiring ML. Further, a magnetoresistive element R3 and a magnetoresistive element R4 are connected in series between the power supply node Np1 and the power supply node Np2 via the output node No2 and the metal wiring ML. Hereinafter, in this specification, a region surrounded by the magnetoresistive elements R1 to R4 connected by the metal wiring ML is defined as a “bridge circuit internal region”.

(Pad and wiring arrangement)
The power supply pad Pp1, the power supply pad Pp2, and the output pad Po1 are disposed outside the bridge circuit internal region. On the other hand, the output pad Po2 is disposed inside the bridge circuit internal region. The signal wiring Lin1 and the signal wiring Lin2 are both on the side where the output pad Po1 is disposed with respect to the Wheatstone bridge circuit, and are disposed so as to extend in the Y direction. The output pad Po1 and one end of the signal wiring Lin1 are connected by a bonding wire BW. Similarly, the output pad Po2 and one end of the signal wiring Lin2 are connected by the bonding wire BW. The other ends of the signal line Lin1 and the signal line Lin2 are connected to the positive input and the negative input of the differential amplifier circuit 2, respectively. The bonding wire BW constitutes a metal wiring.

As described later, the extending direction of the bonding wire BW connecting the output pad Po1 / Po2 and the signal wiring Lin1 / Lin2 is preferably the X direction, which is the magnetosensitive direction of the magnetoresistive elements R1 to R4. Moreover, it is preferable that the dimension of the bonding wire BW in the Z direction is small. As the wire bonding method, ball bonding or wedge bonding is appropriately selected. Further, the method of electrically connecting the output pads Po1 / Po2 and the signal wirings Lin1 / Lin2 is not limited to wire bonding, and a method of fixing metal wiring by bump bonding or solder or conductive adhesive is also applicable. It is. Further, the shape of the bonding pad such as the output pad Po1 is not limited to a rectangle, and may be a polygon or a circle.

The signal wiring Lin1 and the signal wiring Lin2 are arranged in parallel at a predetermined interval D1. The distance D1 is preferably as small as possible. As an example, the minimum value of the processing dimension of the signal wiring Lin1 and the signal wiring Lin2 is applied. When another wiring or electrode set in a state in which a predetermined voltage is applied or in a floating state is disposed between the signal wiring Lin1 and the signal wiring Lin2, the other wiring or electrode and the signal wiring Lin1 or signal It is preferable to set the distance between the signal line Lin1 and the signal line Lin2 short while appropriately maintaining the distance from the line Lin2.

One end of the power supply wiring Lvcc is connected to the power supply pad Pp1 by a bonding wire BW. The other end of the power supply line Lvcc is connected to the positive electrode of the DC power supply 3 through a power supply terminal VCC (see FIG. 1). One end of the power supply line Lgnd is connected to the power supply pad Pp2 by a bonding wire BW. The other end of the power supply line Lgnd is connected to the negative electrode of the DC power supply 3 via a power supply terminal GND (see FIG. 1).

With reference to FIG.2 (b), sectional drawing of the magnetic sensor 10 is demonstrated. FIG. 2B shows a state in which the magnetoresistive element R1, the magnetoresistive element R3, the signal wiring Lin1, and the signal wiring Lin2 are formed on the semiconductor substrate SUB. The magnetoresistive elements R1 to R4 and the like are insulated from the semiconductor substrate SUB by an insulating film (not shown) formed on the surface of the semiconductor substrate SUB. The insulating film is made of, for example, silicon dioxide (SiO ₂ ).

In FIG. 2B, a state in which a barber pole-shaped electrode is formed on the magnetic film Mg including the magnetoresistive element R1 and the magnetoresistive element R3 is shown in a simplified manner. The signal wiring Lin1 and the signal wiring Lin2 are arranged on the left side of the magnetoresistive element R1 in the drawing, that is, on the side where the output pad Po1 is arranged. The distance D1 between the signal wiring Lin1 and the signal wiring Lin2 is preferably set to the minimum value of wiring processing dimensions.

In FIG. 2B, which is a cross-sectional view taken along line IIb-IIb in FIG. 2A, the bonding wire BW is not shown, but the shape of the bonding wire BW will be described below. Inside the bridge circuit internal region, the output pad Po2 is disposed between the magnetoresistive element R1 and the magnetoresistive element R3. The output pad Po2 and the signal wiring Lin2 are connected to each other by a bonding wire BW having a loop height (dimension in the Z direction) that exceeds the magnetoresistive element R1. Similarly, the output pad Po1 and the signal line Lin1 arranged outside the bridge circuit internal region are connected to each other by the bonding wire BW.

(Suppression effect of closed-loop induced electromotive force)
The effect of suppressing the closed-loop induced electromotive force in the magnetic sensor 10 will be described.

As described above, a closed loop is formed by the signal wiring Lin1 and the signal wiring Lin2 between the output node No1 and the output node No2 of the Wheatstone bridge circuit and the positive input and the negative input of the differential amplifier circuit 2. The induced electromotive force generated in the closed loop is mainly determined by the area D1 between the signal wiring Lin1 and the signal wiring Lin2 and the opposing length, and the loop area of the bonding wire BW that connects the signal wiring Lin1 and the output pad Po1. And the loop area of the bonding wire BW connecting the signal line Lin2 and the output pad Po2.

In the magnetic sensor 10 according to the first embodiment, the output pad Po2 is disposed inside the bridge circuit internal region, and the output pad Po1 is disposed on the left outer side in FIG. 2A of the bridge circuit internal region. . Since the signal wiring Lin1 and the signal wiring Lin2 are disposed adjacent to each other on the side where the output pad Po1 is disposed with respect to the Wheatstone bridge circuit, the signal wiring Lin1 and the signal wiring Lin2 are arranged in the Z direction passing between the signal wiring Lin1 and the signal wiring Lin2. Noise due to the magnetic field is reduced.

The direction of the bonding wire BW that connects the signal line Lin1 and the output pad Po1 and the direction of the bonding wire BW that connects the signal line Lin2 and the output pad Po2 are the magnetosensitive directions of the magnetoresistive elements R1 to R4. The direction is set almost the same as the direction. Therefore, noise generated in the bonding wire BW due to the magnetic field in the X direction is also reduced.

Since the output pad Po2 is arranged inside the bridge circuit internal region, the loop of the bonding wire BW that connects the output pad Po2 and the signal wiring Lin2 as compared with the case where the output pad Po2 is arranged outside (right side) the bridge circuit internal region. The height can be lowered. As a result, noise generated in the bonding wire BW due to the magnetic field in the Y direction is also reduced.

As described above, a closed loop is formed by a pair of signal wirings connecting the output terminal of the Wheatstone bridge circuit and the input terminal of the differential amplifier circuit. The induced electromotive force generated in the closed loop can be suppressed by appropriately setting the interval between the signal wiring Lin1 and the signal wiring Lin2, the loop direction or the loop height of the bonding wire BW. By suppressing the induced electromotive force generated in the closed loop, noise superimposed on the input signal of the differential amplifier circuit 2 is reduced, and the detection accuracy of the magnetic sensor 10 is improved.

FIG. 3 is a layout diagram of a magnetic sensor 10R according to a comparative example of the magnetic sensor 10 according to the first embodiment.

In FIG. 3, those denoted by the same reference numerals as those in FIG. 2 have the same configuration or function, and therefore, repeated description thereof will not be repeated. The magnetic sensor 10R in FIG. 3 corresponds to the magnetic sensor 10 in FIG. 2 in which the output pad Po2 is arranged on the right outer side in the drawing of the internal area of the bridge circuit, and the signal wiring Lin2 is also arranged on the output pad Po2 side. To do.

In the magnetic sensor 10R, the output pad Po2 and the signal wiring Lin2 are arranged at positions facing the output pad Po1 and the signal wiring Lin1 across the magnetoresistive elements R1 to R4. As a result, the distance D1R between the signal wiring Lin1 and the signal wiring Lin2 is increased by at least a distance corresponding to the arrangement region of the magnetoresistive elements R1 to R4, compared to the corresponding distance D1 in the magnetic sensor 10. Therefore, the induced electromotive force generated due to the magnetic field in the Z direction, that is, the noise is greatly increased as compared with the case of the magnetic sensor 10, so that the detection accuracy of the magnetic sensor 10R is greatly reduced.

<Modification 1 of Embodiment 1>
FIG. 4 is a layout diagram of the magnetic sensor 11 according to the first modification of the first embodiment.

FIG. 4A is a plan view of the magnetic sensor 11. FIG. 4B is a cross-sectional view of the magnetic sensor 11 taken along line IVb-IVb in FIG.

In FIG. 4, components having the same reference numerals as those in FIG. 2 have the same configuration or function, and therefore, repeated description thereof will not be repeated. The magnetic sensor 11 shown in FIG. 4 includes the magnetoresistive elements R1 to R4, the power supply pads Pp1, the power supply pads Pp2, the output pads Po1, and the output pads Po2 in the magnetic sensor 10 shown in FIG. On the other hand, the signal wiring Lin1, the signal wiring Lin2, the power supply wiring Lvcc, and the power supply wiring Lgnd correspond to those arranged on the wiring board PCB. The wiring board PCB is, for example, a glass epoxy board.

As shown in FIG. 4A, the semiconductor substrate SUB on which the Wheatstone bridge circuit composed of the magnetoresistive elements R1 to R4 is formed is mounted on the wiring board PCB. The output pad Po1 and the output pad Po2 arranged on the semiconductor substrate SUB are connected to the signal wiring Lin1 and the signal wiring Lin2 by the bonding wire BW, respectively. Similarly, the power supply pad Pp1 and the power supply pad Pp2 arranged on the semiconductor substrate SUB are also connected to the power supply line Lvcc and the power supply line Lgnd by bonding wires BW, respectively. The stretching direction of the total four bonding wires BW is preferably aligned with the X direction, which is the magnetosensitive direction of the magnetoresistive elements R1 to R4.

As understood from FIG. 4B, the loop length and the loop height of the bonding wire BW connecting the output pad Po1 disposed on the semiconductor substrate SUB and the signal wiring Lin1 disposed on the wiring substrate PCB are as follows. It increases compared to the case of the magnetic sensor 10 according to the first embodiment. However, the semiconductor substrate SUB (not shown) on which the differential amplifier circuit 2 is formed and the semiconductor substrate SUB on which the Wheatstone bridge circuit composed of the magnetoresistive elements R1 to R4 is mounted are mounted on the same wiring board PCB. As a result, the magnetic sensor circuit 100 can be reduced in size. Furthermore, the semiconductor substrate SUB on which the differential amplifier circuit 2 is disposed and the semiconductor substrate SUB on which the Wheatstone bridge circuit is formed are mounted adjacently on the wiring substrate PCB, so that the signal wiring Lin1 and the signal wiring Lin2 Since the wiring length becomes shorter, noise caused by the magnetic field in the Z direction is reduced.

<Modification 2 of Embodiment 1>
FIG. 5 is a layout diagram of the magnetic sensor 12 according to the second modification of the first embodiment.

In FIG. 5, those given the same reference numerals as those in FIG. 2 have the same configuration or function, and therefore, repeated description thereof will not be repeated. The magnetic sensor 12 of FIG. 5 corresponds to a configuration in which the interval between the power supply line Lvcc and the power supply line Lgnd is set to be the same as the interval D1 between the signal line Lin1 and the signal line Lin2 in the magnetic sensor 10 of FIG. .

As shown in FIG. 5, the power supply wiring Lvcc is formed to extend in the Y direction, like the power supply wiring Lgnd. One end of the power supply line Lvcc is connected to the power supply pad Pp1 by a bonding wire BW. One end of the power supply line Lgnd is connected to the power supply pad Pp2 by a bonding wire BW. The other end of the power supply line Lvcc is arranged so as to maintain a distance D1 from the other end of the power supply line Lgnd extending in the Y direction. The other end of the power supply line Lvcc is connected to the positive electrode of the DC power supply 3 through a power supply terminal VCC (see FIG. 1). The other end of the power supply line Lgnd is connected to the negative electrode of the DC power supply 3 via a power supply terminal GND (see FIG. 2).

A closed loop is formed by the signal wiring Lin1 and the signal wiring Lin2 between the output node No1 and the output node No2 of the Wheatstone bridge circuit and the positive input and the negative input of the differential amplifier circuit 2. The induced electromotive force generated in the closed loop due to the magnetic field in the Z direction is superimposed as noise on the input signal of the differential amplifier circuit 2 and also superimposed on the power supply voltage of the Wheatstone bridge circuit as noise. The power supply voltage noise of the Wheatstone bridge circuit appears as noise in the output voltage of the Wheatstone bridge circuit and adversely affects the measurement accuracy of the magnetic sensor 12.

By setting the interval between the power supply line Lvcc and the power supply line Lgnd to be approximately the same as the interval D1 between the signal line Lin1 and the signal line Lin2, the magnetic sensor 12 can be further improved in accuracy. The direction of the bonding wire BW connecting the power supply pad Pp1 and the power supply wiring Lvcc and the direction of the bonding wire BW connecting the power supply pad Pp2 and the power supply wiring Lgnd are both in the magnetosensitive direction of the magnetoresistive elements R1 to R4. It is preferable to set in the X direction.

In FIG. 5, the extending direction (negative Y direction) of the power supply wiring Lvcc and the power supply wiring Lgnd and the extending direction (positive Y direction) of the signal wiring Lin1 and the signal wiring Lin2 extend in directions opposite to each other. The wiring may be arranged such that these directions are the same. In addition, even when another wiring is arranged between the power supply wiring Lvcc and the power supply wiring Lgnd, the power supply wiring Lvcc or the power supply wiring Lgcc and the power supply wiring Lvcc can be appropriately maintained while keeping the distance between the power supply wiring Lvcc and the other wiring. A similar effect can be obtained by setting the distance from the power supply line Lgnd to be short.

<Modification 3 of Embodiment 1>
FIG. 6 is a layout diagram of the magnetic sensor 13 according to the third modification of the first embodiment. FIG. 6A is a plan view of the magnetic sensor 13. FIG. 6B is a cross-sectional view of the magnetic sensor 13 taken along the line VIIb-VIIb in FIG.

In FIG. 6, those denoted by the same reference numerals as those in FIG. 4 have the same configuration or function, and therefore, repeated description thereof will not be repeated. The magnetic sensor 13 of FIG. 6 is the same as the magnetic sensor 11 of FIG. 4 except that the semiconductor substrate SUB includes the magnetoresistive elements R1 to R4, the power supply pad Pp1, the power supply pad Pp2, the output pad Po1, and the output pad Po2. However, this corresponds to a configuration mounted in a DIP (Dual Inline Package) type package instead of the wiring board PCB.

As shown in FIG. 6A, the semiconductor substrate SUB is mounted on the island of the lead frame LF. The power supply pad Pp1, the power supply pad Pp2, the output pad Po1, and the output pad Po2, each of which is disposed on the semiconductor substrate SUB, correspond to the corresponding lead electrodes among the plurality of lead electrodes of the lead frame LF by the bonding wires BW. Connected with. Each pad (power supply pad Pp1, power supply pad Pp2, output pad Po1, and output pad Po2) on the semiconductor substrate SUB is sealed with resin MLD. Each of the pads is connected to a corresponding one of the power supply wiring Lvcc, the power supply wiring Lgnd, the signal wiring Lin1, and the signal wiring Lin2 arranged on the wiring board PCB via the corresponding lead electrode. ing.

Even when the semiconductor substrate SUB on which the magnetoresistive elements R1 to R4 are arranged is mounted on a general package, the wiring pattern of the wiring substrate PCB on which the package is mounted is formed as close as possible to induce The influence of noise caused by the electromotive force is suppressed.

<Embodiment 2>
FIG. 7 is a layout diagram of the magnetic sensor 20 according to the second embodiment.

In FIG. 7, those denoted by the same reference numerals as those in FIG. 2 have the same configuration or function, and therefore, repeated description thereof will not be repeated. The magnetic sensor 20 of FIG. 7 has a configuration in which one of the power pad Pp1 and the power pad Pp2 is disposed in the bridge circuit internal region instead of one of the output pad Po1 and the output pad Po2. It corresponds to. Specifically, the power supply pad Pp2 is disposed inside the bridge circuit internal region, and the power supply pad Pp1, the output pad Po1, and the output pad Po2 are disposed outside the bridge circuit internal region.

One end of the signal wiring Lin1 and the output pad Po1 are connected to each other by a bonding wire BW. Similarly, one end of the signal line Lin2 and the output pad Po2 are connected to each other by a bonding wire BW. The signal wiring Lin1 and the signal wiring Lin2 are arranged to face each other at a predetermined interval D1. One end of the power supply line Lvcc and the power supply pad Pp1 are connected to each other by a bonding wire BW. Similarly, one end of the power supply line Lgnd and the power supply pad Pp2 are connected to each other by a bonding wire BW. The power supply wiring Lvcc and the power supply wiring Lgnd are arranged to face each other with a predetermined distance D1. The interval D1 is preferably set to the minimum value of the processing dimensions of the signal wiring Lin1 and the signal wiring Lin2.

The induced electromotive force caused by the magnetic field in the Z direction can be minimized by arranging the signal wiring Lin1 and the signal wiring Lin2 so as to face each other at the interval D1, and therefore the magnetic sensor 20 due to noise superimposed on the power supply voltage of the Wheatstone bridge circuit. Measurement accuracy degradation is suppressed.

<Modification of Embodiment 2>
FIG. 8 is a layout diagram of a magnetic sensor 21 according to a modification of the second embodiment.

FIG. 8A is a plan view of the magnetic sensor 21. FIG. 8B is a cross-sectional view of the magnetic sensor 21 taken along line VIIIb-VIIIb of FIG.

In FIG. 8, those denoted by the same reference numerals as those in FIG. 4 have the same configuration or function, and therefore, repeated description thereof will not be repeated. The magnetic sensor 21 in FIG. 8 corresponds to a configuration in which the linear signal wiring Lin1 and the signal wiring Lin2 arranged opposite to each other in the magnetic sensor 11 in FIG. 4 are replaced with wirings that vertically cross each other.

A plan view of the magnetic sensor 21 will be described with reference to FIG. The magnetic sensor 21 includes a semiconductor substrate SUB mounted on one surface of the wiring board PCB, a signal wiring Lin1 and a signal wiring Lin2 each formed on both surfaces (first and second surfaces) of the wiring board PCB, Each includes a power supply line Lvcc and a power supply line Lgnd arranged on one surface of the wiring board PCB. On the semiconductor substrate SUB, magnetoresistive elements R1 to R4 constituting a Wheatstone bridge circuit, an output pad Po1 and an output pad Po2, and a power supply pad Pp1 and a power supply pad pp2 are arranged. An output pad Po2 is disposed inside the bridge circuit internal region, and an output pad Po1 is disposed outside the bridge circuit internal region.

The signal wiring Lin1 and the signal wiring Lin2 are formed on the first surface (the surface in the positive Z direction) and the second surface (the surface in the negative Z direction) of the wiring board PCB so as to cross each other vertically. Yes. The first surface and the second surface are opposed to each other. The first portion L11 of the signal wiring Lin1 is formed on the first surface of the wiring board PCB, and is connected to the output pad Po1 by the bonding wire BW. Similarly, the first portion L21 of the signal wiring Lin2 is formed on the first surface of the wiring board PCB and is connected to the output pad Po2 by the bonding wire BW. The direction of both the bonding wires BW is preferably set in the X direction, which is the magnetic sensitive direction of the magnetoresistive elements R1 to R4.

The first portion L11 of the signal wiring Lin1 connected to the output pad Po1 via the bonding wire BW is formed on the second surface of the wiring board PCB via the via VIA formed on the wiring board PCB. It is connected to one end of the second portion L12 of Lin1. The first portion L11 of the signal wiring Lin1 is a rectangular pattern arranged in the Y-axis direction, and the second portion L12 of the signal wiring Lin1 is a rectangular pattern inclined 45 degrees to the right, for example, with respect to the Y-axis direction. .

The first portion L21 of the signal wiring Lin2 connected to the output pad Po2 via the bonding wire BW is connected to the second portion L22 of the signal wiring Lin2 formed on the second surface of the wiring board PCB via the via VIA. Connected to one end. The second portion L22 of the signal wiring Lin2 is a rectangular pattern inclined 45 degrees to the right with respect to the Y-axis direction, and the first portion L21 of the signal wiring Lin2 is a rectangle inclined 45 degrees to the left with respect to the Y-axis direction. It is a pattern. Therefore, the second portion L22 of the signal wiring Lin2 formed on the second surface of the wiring board PCB and the first portion L21 of the signal wiring Lin2 formed on the first surface of the wiring board PCB are mutually in plan view. Arranged to intersect vertically.

Hereinafter, similarly, the signal wiring Lin1 and the signal wiring Lin2 are alternately formed on the first surface and the second surface of the wiring board PCB so as to intersect each other in plan view. The other end of the signal wiring Lin1 and the other end of the signal wiring Lin2 are formed on a surface (first surface) on which the power supply wiring Lvcc and the power supply wiring Lgnd are arranged.

FIG. 8B is a cross-sectional view of the magnetic sensor 21 taken along line VIIIb-VIIIb in FIG. With reference to FIG. 8B, as described above, the magnetoresistive elements R1 to R4 constituting the Wheatstone bridge circuit, the output pad Po1, the output pad Po2, and the power supply pad Pp1 are formed on the first surface of the wiring board PCB. In addition, the semiconductor substrate SUB on which the power supply pad Pp2 is disposed is mounted, and the signal wiring Lin1 and a part of the signal wiring Lin2 are formed. The power supply wiring Lvcc and the power supply wiring Lgnd are disposed on the first surface of the wiring board PCB. On the second surface of the wiring board PCB, the signal wiring Lin1 and a part of the signal wiring Lin2 are formed via the via VIA.

(effect)
The effect of the magnetic sensor 21 will be described.

The magnetic sensor 21 has a signal wiring Lin1 and a signal wiring Lin2. The signal wiring Lin1 and the signal wiring Lin2 are alternately formed on the first surface and the second surface of the wiring board PCB, and are arranged so as to intersect in plan view. Since the signal wiring Lin1 and the signal wiring Lin2 have a twist structure, the induced electromotive force generated in these signal wirings due to the magnetic field is canceled out, so that the detection accuracy of the magnetic sensor 21 can be improved. .

In the above description, the magnetic sensor 21 is such that a signal wiring pair having a twist structure is formed on a wiring board PCB having a pattern formed on both of two opposing surfaces. A wiring board having a pattern formed on only one of the two surfaces may have a wiring pair having a similar twist structure. For example, instead of connecting the wirings formed on both of the two opposing surfaces with vias, the wirings formed on only one of the two opposing surfaces are alternately connected by bonding wires, It is also possible to realize a twist structure. Further, instead of the bonding wire, the wiring may be connected so as to intersect with each other using solder, or a twisted metal lead wire may be mounted on the wiring board.

<Embodiment 3>
FIG. 9 is a layout diagram of the magnetic sensor 30 according to the third embodiment.

In FIG. 9, those denoted by the same reference numerals as those in FIG. 2 have the same configuration or function, and therefore, repeated description thereof will not be repeated. The magnetic sensor 30 in FIG. 9 corresponds to a configuration in which the magnetoresistive elements R1 to R4 in the magnetic sensor 10 in FIG. 2 are each formed by connecting three magnetoresistive elements R in a meander shape. The configuration of the magnetoresistive element R is the same as that of the magnetoresistive element R1 of the magnetic sensor 10 of FIG. The bridge circuit internal region corresponds to a region surrounded by a total of twelve magnetoresistive elements R connected by the metal wiring ML.

The output pad Po2 is disposed inside the bridge circuit internal region, and the output pad Po1, the power pad Pp1, and the power pad Pp2 are disposed outside the bridge circuit internal region. The signal wiring Lin1 and the signal wiring Lin2 arranged in parallel with the minimum processing dimension are respectively connected to the output pad Po1 and the output pad Po2 via the bonding wire BW. Similarly, the power supply wiring Lvcc and the power supply wiring Lgnd are also connected to the power supply pad Pp1 and the power supply pad Pp2 through the bonding wires BW, respectively. By arranging the power supply line Lvcc and the power supply line Lgnd in parallel with the minimum processing size, the detection accuracy of the magnetic sensor 30 is further improved.

According to the magnetic sensor 30, by applying the above-described configuration also to a Wheatstone bridge circuit composed of meandering magnetoresistive elements, induction caused by the interval between the signal wiring Lin1 and the signal wiring Lin2 or the loop shape of the bonding wire BW. Since the electromotive force is suppressed, the detection accuracy of the magnetic sensor 30 can be improved.

<Modification of Embodiment 3>
FIG. 10 is a layout diagram of a magnetic sensor 31 according to a modification of the third embodiment.

In FIG. 10, the same reference numerals as those in FIG. 9 have the same configuration or function, and therefore, repeated description thereof will not be repeated. The magnetic sensor 31 in FIG. 10 corresponds to a configuration in which the extending directions of the power supply wiring Lvcc and the power supply wiring Lgnd are set in opposite directions to the magnetic sensor 30 in FIG.

In the magnetic sensor 30 of FIG. 9, the signal wiring Lin1 and the signal wiring Lin2, and the power supply wiring Lvcc and the power supply wiring Lgnd are all extended in the same direction (positive Y direction). On the other hand, in the magnetic sensor 31 shown in FIG. 10, the extending direction of the signal wiring Lin1 and the signal wiring Lin2 (positive Y direction) and the extending direction of the power supply wiring Lvcc and the power supply wiring Lgnd (negative Y direction) Are set in opposite directions. The difference between the magnetic sensor 30 and the magnetic sensor 31 is mainly that the semiconductor substrate SUB on which the magnetoresistive element R is formed, the differential amplifier circuit 2 connected to the signal wiring Lin1 and the signal wiring Lin2, the power supply wiring Lvcc and the power supply This is due to the arrangement relationship of the power supply circuit connected to the wiring Lgnd on the mounting substrate.

<Current sensor>
FIG. 11 is a circuit diagram illustrating a configuration of a current sensor circuit 200 including the magnetic sensor 10 according to the first embodiment.

Referring to FIG. 11, current sensor circuit 200 amplifies the outputs of two magnetic sensor circuits 100 by differential amplifier circuit 2cs, and generates current sensor output VoC. A DC power supply 3 is connected between the power supply terminal VCC and the power supply terminal GND of each magnetic sensor circuit 100. FIG. 11 shows an example in which the magnetic sensor circuit 100 includes the magnetic sensor 10 and the differential amplifier circuit 2 according to the first embodiment, but the magnetic sensor 10 may be replaced with a magnetic sensor according to another embodiment. good.

FIG. 12 is a perspective view for explaining the arrangement of the magnetic sensor 10 included in the current sensor circuit 200 shown in FIG.

11 and 12, the two magnetic sensors 10 included in the current sensor circuit 200 of FIG. 11 are arranged so as to sandwich the conductor 4 through which the current to be measured flows. The magnetic flux generated by the current flowing through the conductor 4 is generated in the magnetosensitive direction of the magnetoresistive elements R1 to R4 constituting the Wheatstone bridge circuit of the magnetic sensor 10. The difference between the output voltages of the magnetic sensors 10 is amplified by a differential amplifier circuit 2cs (see FIG. 11) included in the current sensor circuit 200, and is output as a current sensor output VoC.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

2, 2 cs differential amplifier circuit, 3 DC power supply, 4 conductors, 10, 10R, 11, 12, 13, 14, 20, 21, 30 magnetic sensor, 100 magnetic sensor circuit, 200 current sensor circuit, BW bonding wire, D1 , D1R interval, GMR giant magnetoresistive effect, GND power terminal, LF lead frame, Lgnd, Lvcc power wiring, Lin1, Lin2 signal wiring, Mg magnetic film, ML metal wiring, MLD resin, No1, No2 output node, Np1, Np2 Power node, PCB wiring board, Po1, Po2 output pad, Pp1, Pp2 power pad, R, R1-R4 magnetoresistive element, SUB semiconductor substrate, TMR tunnel magnetoresistive effect, VCC power terminal, VIA via, Vo magnetic sensor output, VoC current sensor Force.

Claims

A magnetic sensor,
Wheatstone bridge circuit,
A pair of power wires,
A pair of signal wires;
A pair of power pads;
A pair of output pads,
The Wheatstone bridge circuit is
A pair of power supply nodes;
A pair of output nodes;
A first magnetoresistive element and a second magnetoresistive element connected in series between the pair of power supply nodes via one of the pair of output nodes;
A third magnetoresistive element and a fourth magnetoresistive element connected in series between the pair of power supply nodes via the other of the pair of output nodes;
The pair of power supply nodes are connected to the pair of power supply wirings through the pair of power supply pads,
The pair of output nodes are connected to the pair of signal wirings through the pair of output pads,
The pair of signal wires are magnetic sensors arranged in parallel.
One of the pair of output pads is disposed in a bridge circuit internal region surrounded by the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element. The magnetic sensor according to claim 1.
The other of the pair of output pads is disposed outside the bridge circuit internal region,
3. The magnetic sensor according to claim 2, wherein the pair of signal wirings are disposed on a side where the other of the pair of output pads is disposed with respect to the Wheatstone bridge circuit.
One of the pair of output pads and one of the pair of signal wirings are connected by a first metal wiring,
The magnetic sensor according to claim 3, wherein the other of the pair of output pads and the other of the pair of signal wirings are connected by a second metal wiring.
The magnetic sensor according to claim 3, wherein the pair of signal wirings have a twist structure.
2. The first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element are all composed of meandered magnetoresistive elements. The magnetic sensor according to any one of claims 5 to 6.
The Wheatstone bridge circuit, the pair of power supply wirings, the pair of signal wirings, the pair of power supply pads, and the pair of output pads are disposed on a semiconductor substrate. The magnetic sensor described.
The Wheatstone bridge circuit, the pair of power supply pads, and the pair of output pads are disposed on a semiconductor substrate,
The pair of power supply wirings and the pair of signal wirings are arranged on a wiring board,
The magnetic sensor according to any one of claims 1 to 5, wherein the semiconductor substrate is mounted on the wiring board.