JPWO2011155526A1 - Fluxgate sensor and electronic compass and ammeter using the same - Google Patents

Abstract

A first wiring layer formed on the substrate; a first insulating layer formed to cover the first wiring layer; a central portion formed on the first insulating layer; and a width of the central portion Formed on the first insulating layer so as to cover the magnetic core, and a magnetic core having a pair of end portions having a wider width and a transition portion forming a connection portion between the end portion and the central portion. A second insulating layer and a second wiring layer formed on the second insulating layer, and the first wiring layer and the second wiring layer are electrically connected to each other, A first solenoid coil wound around the pair of end portions and a second solenoid coil wound around the center portion are configured, and the width of the center portion gradually decreases from both ends toward the center. A fluxgate sensor characterized by

Description

The present invention relates to a fluxgate sensor, an electronic compass and an ammeter using the same. In particular, the present invention relates to a fluxgate sensor having high excitation efficiency and low magnetic field dependency, and an electronic compass and ammeter using the fluxgate sensor.
This application claims priority on June 9, 2010 based on Japanese Patent Application No. 2010-132447 for which it applied to Japan, and uses the content for it here.

  As an electronic azimuth meter used for a mobile phone, a portable navigation device, a game controller, etc., an electronic azimuth meter in which three magnetic sensors arranged so that the magnetic sensitive directions of the sensors cross each other is used. . Further, as an ammeter for measuring a current flowing in a conductor such as an electric cable, an ammeter that detects a magnetic field generated by the current with a magnetic sensor and converts it into a current value is used.

  Conventionally, there are magnetic sensors using the Hall effect and those using the magnetoresistive effect (MR) or the giant magnetoresistive effect (GMR). Since these are manufactured by a thin film process, they can be miniaturized and integrated, and are widely used in portable devices and the like. However, these sensors have low sensitivity when they are miniaturized, and it is difficult to detect a geomagnetic level of about 0.3 Oe to be detected with an electronic compass with high accuracy. Therefore, in an electronic azimuth meter using these sensors, the azimuth accuracy is limited to about 10 degrees. Also, when used as an ammeter, the sensitivity is reduced when the device is downsized, and it is difficult to measure the current value with high accuracy.

  On the other hand, in recent years, an electronic compass using a magneto-impedance (MI) sensor (hereinafter referred to as MI sensor) using an amorphous wire and an orthogonal fluxgate sensor has been proposed, and the orientation accuracy is about 2.5 degrees. High accuracy is realized. Further, for example, Patent Documents 1 to 4 disclose an electronic azimuth meter using a small flux gate sensor manufactured by a thin film process. A current sensor (ammeter) using an MI sensor is disclosed in, for example, Patent Document 5.

  By the way, in particular, in order to increase the accuracy of magnetic detection, detection resolution and linearity error determined by the sensitivity of the sensor are important factors. An MI sensor or orthogonal fluxgate sensor and a small fluxgate sensor manufactured by a thin film process have the same resolution. In the case of the MI sensor or the orthogonal fluxgate sensor, due to the hysteresis of the magnetic core, the influence of the hysteresis also appears on the output voltage. Therefore, the linearity error may be deteriorated. In addition, there is a method of using a negative feedback circuit in order to improve linearity, but power consumption becomes large and the circuit becomes complicated.

  On the other hand, in the fluxgate sensor, for example, by using the phase-delay method disclosed in Non-Patent Document 1, a magnetic sensor having good linearity can be realized without being affected by the hysteresis of the magnetic core. . According to this method, the output of the sensor is performed based on the time domain, and it is possible to remove the influence of hysteresis caused by the coercive force of the magnetic core constituting the sensor and to perform digital detection using a counter. Therefore, the influence of the error at the time of analog / digital conversion can be removed, and a sensor with good linearity can be configured. For example, according to Non-Patent Document 2, a linearity of 0.06% FS is realized by using this method. In the MI sensor using the amorphous wire, the linearity error is about 1 to 2%. Thus, by using the flux gate sensor having a good linearity as described above, an electronic azimuth meter with higher azimuth accuracy and higher measurement accuracy are used. An ammeter can be realized.

As described above, an electronic azimuth meter with higher azimuth accuracy and an ammeter with higher measurement accuracy can be configured by a fluxgate sensor using a phase-delay method with high resolution and good linearity.
However, such a fluxgate sensor requires an exciting coil and a detection coil to be wound around the magnetic core. Therefore, it is difficult to reduce the size as compared with the MI sensor or the orthogonal flux gate sensor having a structure in which only the bias coil or the pickup coil is wound.

In addition, in order to realize small integration, attempts have been made to produce a fluxgate sensor by a thin film process as described above. However, the demagnetization increases the demagnetizing field and the sensitivity decreases. In particular, when an electronic azimuth sensor having sensitivity in three mutually orthogonal directions is to be realized, it is necessary to set a magnetosensitive direction in a direction perpendicular to the substrate constituting the electronic azimuth meter. Therefore, it is necessary to mount the sensor element in a state where the sensor element stands vertically on the substrate constituting the electronic azimuth meter.
Therefore, in order to reduce the thickness of the electronic azimuth meter, it is necessary to shorten the length of the magnetic sensing direction of the sensor element that stands vertically to the substrate. For example, when the thickness of the electronic azimuth meter is 1 mm or less, the length of the sensor in the magnetic sensing direction needs to be about 0.5 to 0.7 mm in consideration of the thickness of the substrate and the mold resin. However, when the length of the soft magnetic core is 1 mm or less, the demagnetizing field is increased and the sensitivity is significantly lowered.

  For example, in Patent Document 1 and Patent Document 4, an H-shaped magnetic core in which the width of the outer portion of the magnetic core is wide is used. In this configuration, the excitation coil and the detection coil are wound only on a thin portion at the center of the magnetic core. Therefore, if the size of the sensor element is reduced, the number of turns of both the exciting coil and the detection coil is limited, and it is difficult to secure a sufficient number of turns. Further, the excitation coil and the detection coil are alternately wound. For this reason, the number of turns of the coil is determined by the element size and the coil pitch, and it is difficult to set the number of turns of the detection coil and the pickup coil independently, and the degree of freedom in design is low.

  The present applicant has studied a fluxgate sensor that can secure high excitation efficiency even if it is reduced in size by winding separate coils in a wide area at both ends of the magnetic core and a narrow area at the center. doing. However, if the magnetic core has a portion with a sharp dimensional change, the magnetic flux is locally saturated at the portion, so that the magnetic flux density inside the magnetic core becomes non-uniform, and it is not suitable for a specific external magnetic field or excitation state. Detection characteristics may be significantly degraded. Specific data showing this is shown below.

  FIG. 13 is a diagram showing an example of the shape of a conventional magnetic core. In this conventional magnetic core, the width of the narrow central region (central portion) is uniform, and the side surfaces are straight. Furthermore, the connecting portion (transition portion) of the narrow region at the center and the wide region (end portion) at both ends has a linear taper shape.

  FIG. 14 is a diagram illustrating a result of calculating the magnetic flux density inside the magnetic core with respect to the external magnetic field when the external magnetic field of 12 Oe is applied to the magnetic core having the shape shown in FIG. 13 by the finite element method. The horizontal axis in FIG. 14 corresponds to each position over the entire length in the longitudinal direction of the magnetic core shown in FIG.

  Thus, in the conventional magnetic core, when the width changes linearly in the region where the width of the magnetic core changes, the magnetic flux is likely to be saturated locally at both ends of the narrow region (center portion). On the other hand, the magnetic flux is unsaturated at the center.

  Further, in the fluxgate sensor, it is necessary to perform excitation so as to be saturated alternately positive and negative by the exciting coil. In particular, when the magnetic flux is locally saturated near the entrance of the narrow area in the center, the magnetic flux flows so as to avoid the saturation area. It becomes impossible to excite the whole.

  FIG. 15 is a diagram showing the magnetic field dependence of the pickup voltage in the conventional fluxgate sensor. FIG. 16 is a diagram in which peak values of positive and negative pickup voltages, which are outputs of the fluxgate sensor in each magnetic field, are plotted. In FIG. 16, the magnetic field is changed as “negative → positive → negative” for each of the positive and negative pickup voltages.

  In FIG. 15, the horizontal axis is the time axis, and the time difference between the spike-like pulse on the positive side and the pulse on the negative side represents the strength of the magnetic field. In the case of 0 Oe and 8 Oe, detection is possible, but in the case of 16 Oe, the threshold voltage is not exceeded on the negative side, so that detection is impossible.

  FIG. 16 is a case different from FIG. 15, but shows the horizontal axis as a magnetic field. If it exceeds approximately 12 Oe, it will fall below the threshold value on the positive side, and if it falls below approximately −12 Oe, it will not exceed the threshold value on the negative side. After all, the result is that detection is impossible at 12 Oe or more and −12 Oe or less.

  As described above, when the fluxgate sensor is configured using the magnetic core shown in FIG. 13, in addition to the decrease in excitation efficiency, the output waveform of the fluxgate sensor depends on the magnetic field as shown in FIGS. Increases sex. Thereby, when measuring the time interval between exceeding a threshold voltage, a pick-up voltage may become small by application of an external magnetic field, and may not be detected. In other words, such a fluxgate sensor can exhibit a time interval measurement function only within a limited external magnetic field range (the magnetic field measurement range is narrow).

JP 2007-279029 A JP 2006-234615 A JP 2004-184098 A International Publication No. 2007/126164 Pamphlet JP 2006-172504 A

Pavel Ripka, “Magnetic sensors and magnetometers” p.94, ARTECH HOUSE, INC (2001) IEEE TRABSACTION ON INSTRUCTION AND MEASUREMENT, VOL.42, NO.2, p.635, APRIL 1993

  The present invention provides a fluxgate sensor with high excitation efficiency and low magnetic field dependency, and an electronic compass and ammeter using the same.

The fluxgate sensor of the present invention includes a first wiring layer formed on a substrate, a first insulating layer formed so as to cover the first wiring layer, and a central portion formed on the first insulating layer. A magnetic core having a pair of end portions having a width wider than the width of the central portion, and a transition portion forming a connecting portion between the end portion and the central portion, and so as to cover the magnetic core At least a second insulating layer formed on the first insulating layer and a second wiring layer formed on the second insulating layer, wherein the first wiring layer and the second wiring layer are electrically Are connected to each other to form a first solenoid coil wound around the pair of end portions and a second solenoid coil wound around the center portion. The width may gradually narrow toward the center.
The central portion may have a substantially R shape that is bound inside.
The curvature radius of the central portion may be not less than 5 times and not more than 10 times the length of the central portion.
It is good also considering the connection part vicinity to the said center part of the said transition part as the curve connected to the said R shape.
It is good also considering the connection part vicinity to the said edge part of the said transition part as the curve connected to the linear side surface of the said edge part.
The electronic azimuth meter of the present invention is an electronic azimuth meter comprising a substrate and three fluxgate sensors including at least one of the above-described fluxgate sensors, wherein the three fluxgate sensors correspond to each fluxgate sensor. You may arrange | position on the said board | substrate so that a magnetic sensitive direction may mutually cross.
The magnetic sensing directions of the flux gate sensors may be orthogonal to each other.
The ammeter of the present invention may include a substrate, the fluxgate sensor according to claim 1, and a signal processing IC for converting a magnetic field detected by the fluxgate sensor into a current value.
The fluxgate sensor may be disposed on the substrate such that a magnetic sensitive direction of the fluxgate sensor is parallel to a magnetic field direction.
The measurement system of the present invention includes a conducting wire and two of the above-described ammeters, and the two ammeters have the same distance from the conducting wire, and are arranged at symmetrical positions with the conducting wire in between. Also good.

According to the fluxgate sensor of the present invention, the excitation efficiency is increased, and the variation in the magnitude of the pickup voltage can be reduced even if the magnitude of the applied external magnetic field changes. That is, the magnetic field dependence of the output waveform of the fluxgate sensor can be reduced.
According to the fluxgate sensor of the present invention, the magnetic field dependency can be further suppressed.
According to the present invention, an electronic azimuth meter having high excitation efficiency and low magnetic field dependency can be realized.

1 is a top view schematically showing a fluxgate sensor according to a first embodiment of the present invention. Sectional drawing cut along line a-a 'in FIG. The top view which shows the shape of the magnetic core in the fluxgate sensor of 1st Embodiment. FIG. 6 is a cross-sectional view taken along line b-b ′ in FIG. 1 and showing a process for creating a fluxgate sensor. FIG. 6 is a cross-sectional view taken along line b-b ′ in FIG. 1 and showing a process for creating a fluxgate sensor. FIG. 6 is a cross-sectional view taken along line b-b ′ in FIG. 1 and showing a process for creating a fluxgate sensor. FIG. 6 is a cross-sectional view taken along line b-b ′ in FIG. 1 and showing a process for creating a fluxgate sensor. FIG. 6 is a cross-sectional view taken along line b-b ′ in FIG. 1 and showing a process for creating a fluxgate sensor. The figure which shows the result of having calculated the magnetic flux density inside the magnetic core with respect to the external magnetic field when the predetermined external magnetic field is applied with respect to the fluxgate sensor which concerns on 1st Embodiment by the finite element method. The top view which shows the shape of the magnetic core contained in the fluxgate sensor which concerns on 2nd Embodiment. The figure which shows the result of having calculated the magnetic flux density inside a magnetic core with respect to the external magnetic field when the predetermined external magnetic field is applied with respect to the fluxgate sensor which concerns on 2nd Embodiment by the finite element method. The figure which shows the magnetic field dependence of the pick-up voltage in the fluxgate sensor which concerns on 2nd Embodiment. The figure which plotted the peak value of the positive / negative pick-up voltage which is an output of the fluxgate sensor in each magnetic field in 2nd Embodiment. The relationship between the ratio (R / L) of the R-shaped radius of curvature R of the central portion of the magnetic core and the length L of the central portion, and the magnetic flux density distribution when a magnetic field serving as a saturation region is applied, The figure shown about a ratio. The relationship between the ratio (R / L) of the R-shaped radius of curvature R of the central portion of the magnetic core and the length L of the central portion, and the magnetic flux density distribution when a magnetic field serving as a saturation region is applied, The figure shown about a ratio. The relationship between the ratio (R / L) of the R-shaped radius of curvature R of the central portion of the magnetic core and the length L of the central portion, and the magnetic flux density distribution when a magnetic field serving as a saturation region is applied, The figure shown about a ratio. The relationship between the ratio (R / L) of the R-shaped radius of curvature R of the central portion of the magnetic core and the length L of the central portion, and the magnetic flux density distribution when a magnetic field serving as a saturation region is applied, The figure shown about a ratio. The relationship between the ratio (R / L) of the R-shaped radius of curvature R of the central portion of the magnetic core and the length L of the central portion, and the magnetic flux density distribution when a magnetic field serving as a saturation region is applied, The figure shown about a ratio. The relationship between the ratio (R / L) of the R-shaped radius of curvature R of the central portion of the magnetic core and the length L of the central portion, and the magnetic flux density distribution when a magnetic field serving as a saturation region is applied, The figure shown about a ratio. The figure which expanded and overlapped and showed each waveform corresponding to the center part 2 of FIG. 10A-FIG. 10F. The schematic perspective view of an example of the electronic compass using the pickup coil of the present invention. The figure which shows an example of the shape of the conventional magnetic core. The figure which shows the result of having calculated the magnetic flux density inside a magnetic core with respect to the external magnetic field at the time of applying a predetermined external magnetic field with respect to the magnetic core of the shape shown in FIG. 13 by the finite element method. The figure which shows the magnetic field dependence of the pick-up voltage in the conventional fluxgate sensor. The figure which plotted the peak value of the positive / negative pick-up voltage which is an output of the conventional fluxgate sensor in each magnetic field. The schematic perspective view which shows one usage example of the ammeter using the fluxgate sensor of this invention. The schematic perspective view which shows the structure of the ammeter using the fluxgate sensor of this invention. The schematic perspective view which shows another usage example of the ammeter using the fluxgate sensor of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a top view schematically showing a fluxgate sensor according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line a-a ′ in FIG. 1. FIG. 3 is a top view showing the shape of the magnetic core in the fluxgate sensor according to the first embodiment of the present invention. 4A to 4E are cross-sectional views taken along line b-b 'in FIG.

  As shown in FIGS. 1 and 2, the fluxgate sensor according to the first embodiment of the present invention includes a magnetic core 3, a first wiring layer 4, a first insulating layer 5, a second insulating layer 6, The second wiring layer 7, the opening 8, and the substrate 100 are included. Further, as shown in FIG. 3, the magnetic core 3 includes an end portion 1, a central portion 2, and a transition portion 13 that forms a connecting portion between the end portion 1 and the central portion 2. The first wiring layer 4 and the second wiring layer 7 constitute a first solenoid coil 9 wound around the end portion 1 and a second solenoid coil 10 wound around the central portion 2.

  In the first embodiment of the present invention, the first solenoid coil 9 wound around the end portion 1 is an exciting coil. The second solenoid coil 10 wound around the central portion 2 is a pickup coil. In the first embodiment of the present invention, the end part 1 is an excitation part and the central part 2 is a detection part.

  A manufacturing process of the fluxgate sensor according to the first embodiment of the present invention will be described with reference to FIGS. 4A to 4E. First, as shown in FIG. 4A, the first wiring layer 4 for forming the lower wiring of the solenoid coil is formed on the nonmagnetic substrate 100. Next, as shown in FIG. 4B, the magnetic core 3 and the first insulating layer 5 for insulating the solenoid coil are formed on the first wiring layer 4. Here, in the first insulating layer 5, an opening 8 is provided at a portion where the first wiring layer 4 is connected to the second wiring layer 7 which will be an upper wiring of a solenoid coil to be formed later.

Next, as shown in FIG. 4C, the magnetic core 3 made of a soft magnetic film is formed on the first insulating layer 5.
Here, the shape of the magnetic core 3 made of the soft magnetic film is such that the width at the central portion 2 is narrower than the width at the end portion 1 as shown in FIG. Further, the width of the central portion 2 is gradually narrowed from both ends toward the center. Further, the shape thereof has an R shape that is constricted inward in the central portion 2. Desirably, the radius of curvature R is in the range of 5 to 10 times the longitudinal length L of the central portion 2.
In the first embodiment, the transition portion 13 of the magnetic core 3 has a linear taper shape as in the prior art.

  Next, as shown in FIG. 4D, the second insulating layer 6 in which the opening 8 is provided in the connection portion between the first wiring layer 4 and the second wiring layer 7 is formed on the magnetic core 3. Further, as shown in FIG. 4E, the second wiring layer 7 is formed on the second insulating layer 6 so as to connect the adjacent wirings of the first wiring layer 4 at their end portions, whereby the solenoid A coil is formed. Since the wiring is connected to the adjacent wiring, the loop of the solenoid coil in the cross section is not closed.

  The first solenoid coil 9 and the second solenoid coil 10 formed by the first wiring layer 4 and the second wiring layer 7 are arranged at the wide end portion 1 and the narrow central portion 2 at both ends of the magnetic core 3. , Each is wound independently. The first solenoid coil 9 wound around the wide end portion 1 at both ends includes the third solenoid coil wound around the end portion 1 at one end and the end of the other end. And a fourth solenoid coil wound around portion 1. The third solenoid coil and the fourth solenoid coil at the ends of both ends are connected in series by the first wiring layer 4 or the second wiring layer 7 so that the direction of the generated magnetic field is the same. Thus, the first solenoid coil 9 is formed as a whole. Electrode pads 11 for connecting to the outside are formed at both ends of the second solenoid coil 10 wound around the central portion 2 of the magnetic core 3. Electrode pads 12 for connection to the outside are formed at both ends of two series-connected first solenoid coils 9 wound around the end portions 1 at both ends of the magnetic core 3.

It is preferable that the third solenoid coil and the fourth solenoid coil wound around the end portions 1 at both ends of the magnetic core 3 have the same number of turns and are symmetrical.
FIG. 1 schematically shows the first solenoid coil 9 and the second solenoid coil 10 in which a part of the lower wiring of the magnetic core 3 is omitted. Further, the shapes of the first solenoid coil 9 and the second solenoid coil 10 are not limited to the shapes shown in FIG.

  FIG. 2 is an example of a cross-sectional view of the fluxgate sensor according to the first embodiment of the present invention cut along line aa ′ in FIG. 1, and the fluxgate according to the first embodiment of the present invention. The positional relationship between the first wiring layer 4 and the second wiring layer 7 in the sensor is not limited to the shape shown in FIG.

  4A to 4E are examples of cross-sectional views of the fluxgate sensor according to the first embodiment of the present invention cut along the line bb ′ in FIG. 1, and the first embodiment of the present invention is illustrated in FIGS. The shape of the fluxgate sensor is not limited to the shapes of FIGS. 4A to 4E.

  The wide end portions 1 at both ends of the magnetic core 3 are excited by energizing the first solenoid coil 9 wound around the periphery. On the other hand, an induced voltage is applied to the narrow central portion 2 of the magnetic core 3, and the induced voltage is detected by the second solenoid coil 10 wound around the central portion 2.

  The magnetic core 3 is AC-excited by energizing the first solenoid coil (excitation coil) 9 of the end portion 1 of the magnetic core 3 with an alternating current that changes over time via the electrode pad 12 from the outside. Is done. The magnetic flux generated at the end portion 1 is guided to the central portion 2 of the magnetic core 3. As a result, the central portion 2 of the magnetic core 3 is also AC-excited, and a substantially pulsed induced voltage is generated in the second solenoid coil (detection coil) 10 of the central portion 2. This induced voltage can be detected by an external detection circuit via the second solenoid coil 10 and the electrode pad 11. Here, the alternating current supplied to the first solenoid coil 9 is desirably a triangular wave having a constant frequency.

At this time, when an external magnetic field is applied, the timing at which the above-described substantially pulsed induced voltage is generated changes with time. At the timing of switching from positive to negative in the triangular wave current, a positive induced voltage is output. In addition, a negative induced voltage is output at the timing of switching from negative to positive in the triangular wave current. Therefore, a response to an external magnetic field can be obtained by measuring the timing at which the positive and negative pulsed induced voltages are generated with a counter.
As a configuration of the fluxgate sensor, in addition to the above-described configuration, a sealing layer covering the second wiring layer 7 may be formed.

Next, a method for manufacturing the fluxgate sensor according to the first embodiment of the present invention will be described.
First, a barrier metal such as titanium (Ti), chromium (Cr), or titanium tungsten (TiW) is formed on the nonmagnetic substrate 100 by sputtering, and then copper (Cu) is formed by sputtering. Next, a resist pattern to be the first wiring layer 4 is formed by photolithography, and a wiring pattern is formed by wet etching. Alternatively, the first wiring layer 4 may be formed by electrolytic plating using the sputtered film as a seed film. At this time, since the magnetic core 3 is formed on the insulating layer to be formed later, the thickness of the first wiring layer 4 is such that the unevenness on the surface of the insulating layer due to the wiring is sufficiently smaller than the thickness of the magnetic core. It is desirable that the thickness be such that the coil resistance is small. Specifically, the thickness is preferably about 0.2 μm to 2 μm.

Next, the 1st insulating layer 5 is formed by apply | coating photosensitive resin and performing exposure, image development, and a thermosetting process. At this time, a portion where the first wiring layer 4 and the second wiring layer 7 to be formed later are connected is opened, and the first wiring layer 4 and the magnetic core 3 to be formed later are insulated.
At this time, it is desirable that the thickness of the first insulating layer 5 is sufficient to alleviate the unevenness of the first wiring layer 4. Specifically, the thickness is desirably about 3 to 10 times the thickness of the first wiring layer 4. In FIG. 2, such a ratio is not shown for convenience of display on the drawing of the first wiring layer 4.

  At this time, it is necessary for the photosensitive resin to prevent the magnetic core 3 from being distorted due to shrinkage or deformation due to thermal history in a later process. Therefore, the photosensitive resin is a resin having sufficient heat resistance that does not cause thermal shrinkage or deformation due to, for example, solder reflow during mounting or heat treatment in a magnetic field to impart induced magnetic anisotropy to the magnetic core. Is desirable. Specifically, the glass transition point (Tg: Glass Transition Temperature) of the photosensitive resin is desirably 300 degrees Celsius or higher. That is, the photosensitive resin used here is preferably polyimide, polybenzoxazole having high heat resistance, or a thermosetting novolac resin.

Next, a soft magnetic film serving as the magnetic core 3 is formed by sputtering, and patterning is performed using photolithography and etching so as to obtain a desired shape. As the soft magnetic film, a zero magnetostrictive Co-based amorphous film typified by CoNbZr and CoTaZr, a NiFe alloy, a CoFe alloy, or the like is desirable. Since these soft magnetic films are difficult-to-etch materials, they may be formed by a lift-off method in which a desired pattern is obtained by performing sputter deposition after forming a resist and removing the resist. Further, after the magnetic film to be the magnetic core 3 is formed, in order to remove the stress and the non-uniform uniaxial anisotropy applied at the time of film formation and to provide the uniform induced magnetic anisotropy, a rotating magnetic field It is desirable to perform a middle heat treatment or a heat treatment in a static magnetic field.
Alternatively, the magnetic core 3 may be formed by forming a NiFe alloy or CoFe alloy into a desired shape using an electrolytic plating method using a resist frame.

  Next, the connecting portion between the first wiring layer 4 and the second wiring layer 7 is opened, and the photosensitive resin is exposed, developed, and developed so as to electrically insulate the magnetic core 3 and the second wiring layer 7 from each other. The 2nd insulating layer 6 is formed by performing a thermosetting process.

  Next, a barrier metal such as titanium (Ti), chromium (Cr), titanium tungsten (TiW) or the like is formed on the substrate including the second insulating layer 6 and the opening of the second insulating layer 6 by sputtering, and then Cu is formed. A seed film is formed by forming a film by sputtering. Then, a resist frame is formed, a desired wiring pattern is formed by electrolytic plating of Cu, and the second wiring layer 7 is formed by etching the seed layer.

  Finally, the flux gate sensor according to the first embodiment of the present invention is configured by forming electrode pads, terminals, and protective films for external connection as necessary. Here, as a terminal to be connected to the outside, methods used for general semiconductor devices and thin film devices such as solder bumps and gold bumps, and wire bonding can be applied.

Further, here, as the first and second wiring layers 1 and 5, copper (Cu) by sputtering and electroplating was used, but it may be formed by electroless Cu, electrolytic Au (gold) plating, or the like. A good conductive film made of copper (Cu), aluminum (Al), gold (Au), or the like may be used. The first and second insulating resin layers 2 and 4 are resin materials, and an insulating film such as silicon oxide (SiO ₂ ), silicon nitride (SiN), aluminum oxide (Al ₂ O ₃ ) is sputtered or CVD. It can also be produced by forming a film by using and forming the opening by dry etching.

  FIG. 5 shows a result of calculating the magnetic flux density inside the magnetic core with respect to the external magnetic field by the finite element method when a 12 Oe external magnetic field similar to FIG. 14 is applied to the fluxgate sensor manufactured as described above. FIG. As is clear when compared with the conventional case of the dotted line, a portion that is easily saturated locally does not occur.

  From the above, it can be seen that it is important to constrict the central portion 2 in order to avoid local saturation and increase the excitation efficiency. However, here, the curve has a radius of curvature R, but the width may be narrowed gradually toward the center, and may be linear.

  Next, a fluxgate sensor according to the second embodiment of the present invention will be described. The fluxgate sensor according to the second embodiment differs from the fluxgate sensor according to the first embodiment only in the shape of the magnetic core. Here, only the shape of the magnetic core will be described, and description of common parts will be omitted.

FIG. 6 is a top view showing the shape of the magnetic core included in the fluxgate sensor according to the second embodiment.
In the magnetic core 3 according to the first embodiment, the transition portion 13 has a tapered shape with a linear outer diameter as in the prior art, but in the magnetic core 3A according to the second embodiment, the transition portion 13A. Has a curved outer shape. Specifically, the vicinity of the connection portion to the central portion 2 of the transition portion 13A is a curve that smoothly connects to the R shape. Further, the vicinity of the connection portion of the transition portion 13A to the end portion 1 is a curve that smoothly connects to the straight side surface of the end portion 1.

  FIG. 7 shows the flux density of a flux core sensor having a magnetic core having the above-described shape when the magnetic field density inside the magnetic core with respect to the external magnetic field when a 12 Oe external magnetic field similar to that in FIGS. 14 and 5 is applied. It is a figure which shows the result calculated by the method. Similar to the first embodiment of FIG. 5, there is no portion that is locally saturated compared to the conventional dotted line.

FIG. 8 is a diagram showing the magnetic field dependence of the pickup voltage in the fluxgate sensor according to the second embodiment.
Compared to the conventional case of FIG. 15, due to the decrease in the unsaturated region, the threshold is exceeded on both the positive and negative sides even at 16 Oe, and detection is possible.

FIG. 9 is a diagram in which peak values of positive and negative pickup voltages, which are outputs of the fluxgate sensor in each magnetic field, are plotted in the second embodiment.
Compared with the conventional case of FIG. 16, due to the decrease in the unsaturated region, it is possible to detect even in the case of approximately −12 Oe or less and approximately 12 Oe or more.

  Therefore, it can be seen from FIG. 8 and FIG. 9 that the magnetic field dependence of the pickup voltage is smaller than in the conventional case.

  10A to 10F show the ratio (R / L) between the radius R of curvature R of the central portion 2 of the magnetic core and the length L of the central portion 2 and a magnetic field that becomes a saturation region. It is a figure which shows the relationship with magnetic flux density distribution about each ratio. FIG. 11 is an enlarged view of waveforms corresponding to the central portion 2 in FIGS. 10A to 10F.

As shown in FIG. 10A to FIG. 10F and FIG. 11, when R / L exceeds 10, a region where the magnetic flux is locally saturated appears remarkably on the graph as R / L = 15 [FIG. 10B] It becomes a state close to the case of the conventional straight line.
On the other hand, when R / L is less than 5, a region in which the magnetic flux density has suddenly decreased is observed in the central part of the magnetic core (corresponding to 165 to 315 μm on the horizontal axis of the graph) [FIG. 10F]. That is, contrary to the conventional case where the central portion 2 is a straight line, the vicinity of the center of the central portion 2 is likely to be saturated, and the end portion of the central portion 2 is less likely to be saturated. Thereby, the uniformity of the magnetic flux density is reduced in the central portion 2. In particular, when the radius of curvature is reduced, the saturation region is narrowed, so that the excitation efficiency is reduced. Therefore, in order for the narrow region (center portion) of the magnetic core 3A to be uniformly excited (as a guide, there should be uniformity over 70% or more of the total length of the center portion 2). ), The shape of the central portion of the magnetic core has an R shape, and the ratio of the radius of curvature R and the length L of the constricted portion is considered to be preferably about R / L = 5-10.

  In the second embodiment, the shape of the transition portion 13A is a smooth curve both in the vicinity of the connection portion to the central portion 2 of the transition portion 13A and in the vicinity of the connection portion to the end portion 1 of the transition portion 13A. Making a part. The smooth curve in the vicinity of the connection portion to the central portion 2 of the transition portion 13A contributes more efficiently to suppression of the unsaturated region.

  In the above-described embodiment, the outer first solenoid coil 9 is an excitation coil, and the inner second solenoid coil 10 is a detection coil. A similar result can be obtained with a pickup coil having an inner coil as an excitation coil and an outer coil as a detection coil.

Next, an embodiment of an electronic azimuth meter using the above-described pickup coil will be described. FIG. 12 is a schematic perspective view of the electronic compass.
The electronic compass shown in FIG. 12 includes a first fluxgate (X-axis) sensor 20, a second fluxgate (Y-axis) sensor 30, a third fluxgate (Z-axis) sensor 40, and a signal processing IC 50. It is comprised by arrange | positioning on one board | substrate. Specifically, the first fluxgate sensor 20 and the second fluxgate sensor 30 are arranged so that the formed surface is substantially parallel to the substrate surface constituting the electronic azimuth meter and the magnetic sensitive direction is It arrange | positions so that it may mutually orthogonally cross. The third fluxgate sensor 40 is disposed so as to be substantially perpendicular to the substrate surface constituting the electronic azimuth meter. At this time, the 1st fluxgate sensor 20, the 2nd fluxgate sensor 30, and the 3rd fluxgate sensor 40 are the fields except the connection terminal with the outside, ie, the shape of the portion which forms magnetic core 3 and coils 9,10 Is desirably the same as 1. This is because the characteristics of each of the first fluxgate sensor 20, the second fluxgate sensor 30, and the third fluxgate sensor 40 are aligned, so that it is not necessary to correct variations in the characteristics of each sensor, and the electronic circuit is simplified. This is to make it possible. Further, since the third fluxgate sensor 40 is mounted substantially perpendicularly to the substrate surface, the length in the magnetic sensing direction is preferably 1 mm or less, more preferably, in order to reduce the thickness of the electronic azimuth meter. Is preferably about 0.5 mm.

  The signal processing IC 50 includes a circuit for supplying a triangular wave current of one constant frequency to the excitation coil 9 in each fluxgate sensor, a detection circuit for detecting the induced voltage appearing in the detection coil 10, and the timing at which the induced voltage is generated. A counter for counting and a selector for switching the connection of the two circuits to each of the first fluxgate sensor 20, the second fluxgate sensor 30, and the third fluxgate sensor 40 are provided. With this configuration, the first fluxgate sensor 20, the second fluxgate sensor 30, and the third fluxgate sensor 40 sequentially measure the magnetic field in each of the three axial directions and perform an operation to realize an electronic compass with a small azimuth error. can do.

  Next, an example of an ammeter using the fluxgate sensor of the present invention will be described. FIG. 17 is a schematic perspective view showing an example of an ammeter 90 using the fluxgate sensor of the present invention. FIG. 18 is a schematic perspective view showing the structure of an ammeter 90 using the fluxgate sensor of the present invention.

  For example, as shown in FIG. 18, the ammeter 90 is a combination of a magnetic sensor 41 and a signal processing IC 50 for converting a magnetic field detected by the magnetic sensor 41 into a current value on a printed board 60. . The fluxgate sensor of the present invention is adopted as the magnetic sensor 41 to constitute an ammeter 90.

  As shown in FIG. 17, when a current I flows through a conductor (conductive wire) 70, a magnetic field H is generated concentrically around the conductor 70. When I is the value of the current flowing through the conductor 70 and r is the distance between the ammeter 90 and the conductor 70, the magnetic field H = I / (2πr) can be expressed. As shown in this equation, the closer to the conductor (conductor) 70, the stronger the magnetic field H (higher magnetic flux density). Further, the larger the current flowing through the conductor (conductive wire) 70, the larger the magnetic field H is generated.

  For example, as shown in FIG. 17, when a current I is passed through a linear conductor (conductive wire) 70, a concentric magnetic field H centered on the conductive wire 70 is generated in a plane perpendicular to the conductive wire 70. In FIG. 17, when a current flows in the direction of arrow I, the direction of the magnetic field is the direction of arrow H. The magnitude of the current I flowing through the conducting wire 70 can be measured by arranging the ammeter 90 in the vicinity of the conducting wire 70 and detecting the magnitude of the magnetic field H generated by the current I flowing through the conducting wire 70. The closer to the conducting wire 70, the higher the magnetic flux density of the magnetic field H generated by the current I. Therefore, the closer the ammeter 90 is to the conducting wire 70, the more efficiently the current value can be measured.

  In the ammeter 90, the magnetic sensor (flux gate sensor) 41 is preferably arranged so that the magnetic sensing direction S of the magnetic sensor (flux gate sensor) 41 is parallel to the direction of the magnetic field H generated by the current I. .

  Next, another example of an ammeter using the fluxgate sensor of the present invention will be described. FIG. 19 is a schematic perspective view showing another example of an ammeter using the fluxgate sensor of the present invention.

  In this example, two ammeters (a first ammeter 91 and a second ammeter 92) are arranged in the vicinity of the conducting wire 70. The first ammeter 91 and the second ammeter 92 have the same structure as the ammeter 90 shown in FIG. An arithmetic circuit 80 is connected to the first ammeter 91 and the second ammeter 92. First ammeter 91 and second ammeter 92 detect magnetic field Hi generated by current I flowing through conductive wire 70. Specifically, the first ammeter 91 detects the magnetic field Ha, and the second ammeter 92 detects the magnetic field Hb and outputs it to the arithmetic circuit 80. The arithmetic circuit 80 calculates the magnetic field Hi from the magnetic field Ha and the magnetic field Hb, and outputs the magnitude of the current I flowing through the conductor 70 from the strength of the magnetic field Hi.

  In the first ammeter 91 and the second ammeter 92, the fluxgate sensor 41 included in each ammeter has a substrate so that the magnetic sensing direction S of the fluxgate sensor 41 and the direction of the magnetic field H are parallel to each other. 60. The first ammeter 91 and the second ammeter 92 have the same distance from the conducting wire 70 and are disposed at symmetrical positions with the conducting wire 70 in between.

  Since the measurement system has the above-described configuration, even if a noise magnetic field Hex is externally applied to the measurement system, the external noise magnetic field is calculated by calculating the outputs from the first ammeter 91 and the second ammeter 92. Hex can be canceled and the current I flowing through the conductor 70 can be accurately obtained.

  Details will be described below. Consider a case where an external noise magnetic field Hex is added to this measurement system in a measurement system that measures the current value of the current I by detecting the magnetic field Hi generated by the current I flowing through the conductor 70. At this time, the magnetic field Ha detected by the first ammeter 91 can be expressed as Ha = Hi + Hex. The magnetic field Hb detected by the second ammeter 92 can be expressed as Hb = −Hi + Hex. The direction of the magnetic field Hi generated by the current I is opposite between the position of the first ammeter 91 and the position of the second ammeter 92.

  From the above two formulas, Hex = (Ha + Hb) / 2 and Hi = (Ha−Hb) / 2. That is, it is possible to clarify the magnitude of the external magnetic field noise Hex and detect the magnitude of Hi excluding the external magnetic field noise Hex. Therefore, even if the external noise magnetic field Hex is added, the current value of the current I flowing through the conductor 70 can be accurately measured.

  The present invention can be applied to a fluxgate sensor used in a mobile phone, a portable navigation device, a game controller, and the like, and an electronic compass using the same. In addition, the present invention can be applied to an ammeter that arranges the fluxgate sensor of the present invention in the vicinity of an electric wire, detects a magnetic field generated by a current flowing through the electric wire, and measures a current value.

DESCRIPTION OF SYMBOLS 1 End part of magnetic core 2 Central part of magnetic core 3 Magnetic core 3A Magnetic core 4 1st wiring layer 5 1st insulating layer 6 2nd insulating layer 7 2nd wiring layer 8 Opening part 9 1st solenoid coil 10 2nd Solenoid coil 11 Electrode pad 12 Electrode pad 13 Transition portion 13A Transition portion 20 First flux gate (X-axis) sensor 30 Second flux gate (Y-axis) sensor 40 Third flux gate (Z-axis) sensor 50 Signal processing IC
100 substrates

Claims (10)

A first wiring layer formed on the substrate;
A first insulating layer formed to cover the first wiring layer;
A central portion; a pair of end portions having a width wider than the width of the central portion; and a transition portion forming a connecting portion between the end portion and the central portion. A magnetic core,
A second insulating layer formed on the first insulating layer so as to cover the magnetic core;
At least a second wiring layer formed on the second insulating layer,
When the first wiring layer and the second wiring layer are electrically connected, a first solenoid coil wound around the pair of end portions and a second solenoid coil wound around the center portion Configure the solenoid coil,
The flux gate sensor, wherein the central portion has a width that gradually decreases from both ends toward the center.   The fluxgate sensor according to claim 1, wherein the central portion has a substantially R shape that is bound to the inside.   The fluxgate sensor according to claim 2, wherein a radius of curvature of the central portion is not less than 5 times and not more than 10 times the length of the central portion.   4. The fluxgate sensor according to claim 2, wherein a vicinity of a connection portion of the transition portion to the central portion is a curve connected to the R shape. 5.   The fluxgate sensor according to any one of claims 1 to 4, wherein a vicinity of a connection portion of the transition portion to the end portion is a curve connected to a straight side surface of the end portion. A substrate and three fluxgate sensors comprising at least one fluxgate sensor according to claim 1;
An electronic compass comprising:
The three fluxgate sensors are arranged on the substrate so that the magnetic sensing directions of the fluxgate sensors cross each other.   The electronic azimuth meter according to claim 6, wherein the magnetic sensitive directions of the fluxgate sensors are orthogonal to each other.   An ammeter comprising a substrate, the fluxgate sensor according to claim 1, and a signal processing IC for converting a magnetic field detected by the fluxgate sensor into a current value.   The ammeter according to claim 8, wherein the fluxgate sensor is arranged on the substrate so that a magnetic sensitive direction of the fluxgate sensor is parallel to a magnetic field direction. Comprising a conductor and two ammeters according to claim 9,
The two ammeters have the same distance from the conducting wire, and are arranged at symmetrical positions with the conducting wire in between.

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