JP2012063203A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor excellent in magnetic-field sensitivity anisotropy, wide-operation magnetic field, and output linearity.SOLUTION: The magnetic sensor 20 includes an insulating substrate 20, GMR elements 22a to 22d formed on the surface of the insulating substrate 20, and a bias magnet 24 disposed on the rear surface of the insulating layer 20. The GMR elements 22a to 22d are made of granular thin films folded to extend between one side and the other side. A bias magnetic field is applied from the bias magnet 24 in a longitudinal direction where the GMR elements 22a to 22d linearly extend. The granular thin films of the GMR elements 22a to 22d are formed by dispersing FeCo fine particles in an Ag mother phase.

Description

  The present invention relates to a magnetic sensor for measuring the magnitude and positive / negative polarity (direction) of a magnetic field.

  Conventionally, it is well known to use a magnetic sensor in a current detection device or a rotation detection device. It is also known to use a magnetoresistive element for such a magnetic sensor. The magnetoresistive effect element has a characteristic that the resistance value is changed by a change in the external magnetic field, and outputs the change in the resistance value as a voltage change. Some of such magnetic sensors use GMR elements as magnetoresistive elements in order to increase the output. However, a change in electric resistance of a normal GMR element does not depend on the positive and negative polarities of the magnetic field and has isotropic characteristics. Therefore, in a magnetic sensor using a GMR element, the polarity of the magnetic field has two positive and negative polarities. On the other hand, the same electric resistance is shown, and the positive and negative polarities of the magnetic field cannot be specified. For this reason, there is also a magnetic sensor that can detect the magnitude and positive / negative polarity of the external magnetic field by applying a bias magnetic field to the GMR element (see, for example, Patent Document 1).

  In this magnetic sensor (magnetic field sensor), a pair of magnetic field generation sources consisting of a multilayer film of a soft magnetic thin film and a hard magnetic thin film are formed on the upper surface of the substrate at intervals, and the soft magnetic film is formed on the upper surface of each magnetic field source. A thin film is formed. A GMR element (giant magnetoresistive thin film) is formed between the pair of magnetic field generation sources and the pair of soft magnetic films on the upper surface of the substrate. According to this magnetic sensor, a bias magnetic field can be applied to the GMR element by the magnetic field generation source. Then, by applying a bias magnetic field to the GMR element, it is possible to generate a difference in the output of the magnetic sensor due to the difference in the polarity of the magnetic field. As a result, both the magnitude of the external magnetic field and the positive and negative polarities can be detected.

JP 2003-78187 A

  However, the magnetic sensor described above is still not sufficient in terms of magnetic field anisotropy, wide operating magnetic field and output linearity, and the shape of the GMR element, the direction of the bias magnetic field applied to the GMR element, the GMR There is room for improvement in materials constituting the element.

  The present invention has been made to cope with such problems, and an object thereof is to provide a magnetic sensor excellent in magnetic field sensitivity anisotropy, wide operating magnetic field, and output linearity. In addition, in the description of each constituent element of the present invention below, in order to facilitate understanding of the present invention, reference numerals of corresponding portions of the embodiment are described in parentheses, but each constituent element of the present invention is The present invention should not be construed as being limited to the configurations of the corresponding portions indicated by the reference numerals of the forms.

  In order to achieve the above-described object, the structural features of the magnetic sensor (20, 40, 40a) according to the present invention are formed on the surface of the insulating substrate (21, 41) and the insulating substrate, one side and the other side. GMR elements (22a to 22d, 42a, 42b, 62a to 62d, 72a to 72d) made of linear high-permeability granular thin films that extend while being folded between and an insulating substrate, and the lines of the GMR elements And a bias magnetic field applying means (24, 44) for applying a bias magnetic field in the longitudinal direction in which the shape extends.

  In the magnetic sensor according to the present invention, the GMR element is composed of a granular thin film. This granular thin film is easy to manufacture and has excellent magnetic field sensitivity in which the electrical resistance changes with respect to the magnetic field, but since the magnetization is difficult to saturate and the demagnetizing field due to the external magnetic field is small, the sensitivity anisotropy due to the shape is small. For this reason, in the magnetic sensor according to the present invention, the GMR element is formed in a linear shape extending while being folded between one side and the other side. As a result, the GMR element has shape anisotropy in the longitudinal direction in which the linear shape extends and in the short direction perpendicular to the longitudinal direction. Further, by applying a bias magnetic field in the longitudinal direction in which the GMR element extends by the bias magnetic field applying means, the GMR element is magnetized close to saturation, the demagnetizing effect is enhanced, and the shape anisotropy of sensitivity is increased. As a result, a magnetic sensor having excellent sensitivity anisotropy and capable of detecting positive and negative polarities (directions) of the magnetic field can be obtained.

  Moreover, the occurrence of magnetic hysteresis in the operating magnetic field range can be suppressed by applying a bias magnetic field to bring the GMR element into a magnetization state close to saturation. As a result, the energy in the magnetic field space stored when the magnetic field is increased comes out as it is when the magnetic field is decreased, and energy loss is reduced. Further, in the magnetic field range in which the permeability of the GMR element is high, there is a difference in resistance change rate (sensitivity) between the longitudinal direction and the short direction of the GMR element. For this reason, it is preferable that the magnetic permeability of the GMR element is, for example, 10 or more. That is, in the magnetic sensor according to the present invention, by providing the above-described configuration, it is possible to make the magnetization state close to saturation. Thus, even if the permeability of the GMR element is increased, the longitudinal direction is a demagnetizing field. An operating magnetic field range with less hysteresis and less hysteresis can be obtained. As the bias magnetic field applying means according to the present invention, a bias magnet, a magnetic coil or the like can be used.

  Another structural feature of the magnetic sensor according to the present invention is that the granular thin film constituting the GMR element is constituted by dispersing fine particles made of FeCo in a matrix phase made of Ag. is there. By using this material, it is possible to obtain a GMR element that has high magnetic field sensitivity and responds sensitively to changes in the external magnetic field. In this case, it is preferable to set the atomic composition ratio of the material constituting the GMR element to about 15% for Fe and Co with respect to 70% for Ag.

  Still another structural feature of the magnetic sensor according to the present invention is that the magnitude of the external magnetic field is based on the resistance value generated in the GMR element when an external magnetic field is applied in the longitudinal direction in which the linear shape of the GMR element extends. And detecting positive and negative polarities.

  In the magnetic sensor according to the present invention, the GMR element is formed in a shape having a longitudinal direction and a short direction, thereby giving the GMR element a shape anisotropy and applying a bias magnetic field in the longitudinal direction of the GMR element. Thus, the shape anisotropy of sensitivity is increased, and an external magnetic field is applied to the GMR element to detect the magnitude and positive / negative polarity of the external magnetic field.

  When operating a GMR element by applying a bias magnetic field, the magnitude and direction of the actual operating magnetic field with respect to the external magnetic field is a composite vector of the magnitude and direction of the bias magnetic field and the external magnetic field, and is calculated from the sum of the respective vector components. Is done. In addition, it can be said that a GMR element excellent in sensitivity shape anisotropy can more accurately detect the intensity of a component in the bias magnetic field direction of an external magnetic field vector. In other words, among the vectors of the external magnetic field, the larger the component orthogonal to the bias magnetic field direction, the greater the variation in the magnetization direction with respect to the bias magnetic field direction, making it difficult to accurately detect the sensitivity direction component. In the magnetic sensor according to the present invention, by applying a bias magnetic field in the longitudinal direction of the GMR element, it is possible to more accurately detect the intensity and positive / negative polarity of the component in the bias magnetic field direction among the vectors of the external magnetic field. Is. In this case, as the bias magnetic field is increased, the influence of the component perpendicular to the bias magnetic field direction in the external magnetic field can be reduced.

  Further, another structural feature of the magnetic sensor according to the present invention is that the bias magnetic field applying means is arranged facing the insulating substrate in a state where the magnetic center of the magnetic pole surface is aligned with the center of the insulating substrate (21). The GMR elements (22a to 22d) are formed at the same distance from the central point along two axes extending perpendicular to the central point of the insulating substrate and parallel to the magnetic pole surface. The two bridge circuits are configured by connecting two GMR elements provided along each of the two axes in series, and a power supply voltage is applied to both ends of the two bridge circuits. Thus, the output signals are respectively taken out from the connection points of the two GMR elements.

  According to the present invention, for example, when a magnet is installed on the rotating shaft and a magnetic field that changes as the rotating shaft rotates is detected, the output signals obtained from the two bridge circuits are a cosine wave and a sine wave having a phase difference. Therefore, the rotation direction, rotation speed, and rotation angle of the rotation shaft can be detected. According to this, a magnetic sensor having a function as a rotation sensor excellent in magnetic field sensitivity anisotropy, wide operating magnetic field and output linearity can be obtained. Further, by using a bias magnet as the bias magnetic field applying means, the configuration of the magnetic sensor is simplified.

  Still another structural feature of the magnetic sensor according to the present invention is that the bias magnetic field applying means is composed of a bias magnet (44) magnetized along the back surface of the insulating substrate (41), so that a GMR element is provided. (42a, 42b) is composed of two parts respectively formed on portions corresponding to both poles of the bias magnet on the surface of the insulating substrate, and two GMR elements are connected in series to form a bridge circuit. The power supply voltage is applied to both ends of the GMR element, and the output signals are respectively taken out from the connection points of the GMR elements.

  According to the present invention, for example, when a conductor is installed in the vicinity of an insulating substrate and a current is passed through the conductor, the output signal obtained from the bridge circuit is a voltage corresponding to the magnitude of the current passing through the conductor. Is output as According to this, a magnetic sensor having a function as a current sensor excellent in magnetic field sensitivity anisotropy, wide operating magnetic field, and output linearity can be obtained. Further, by using a bias magnet as the bias magnetic field applying means, the configuration of the magnetic sensor is simplified.

It is the top view which showed the inside of the sensor chip package provided with the magnetic sensor which concerns on 1st Embodiment of this invention. It is 2-2 sectional drawing of FIG. It is the top view which showed the magnetic sensor. 3 is a bridge circuit of the magnetic sensor shown in FIG. 3, (a) is a bridge circuit in the X direction, and (b) is a bridge circuit in the Y direction. The relationship between the magnitude of the magnetic field and the resistance value when an external magnetic field is applied to the GMR element is shown, (a) is a graph when applied in the longitudinal direction, and (b) is a graph when applied in the short direction. It is. It is the graph which showed the relationship between the applied magnetic field of a GMR element, and the magnitude | size of magnetization. The relationship between the magnetic field and the resistance value when an external magnetic field is applied to a GMR element to which a bias magnetic field is applied is shown, (a) is a graph when applied in the longitudinal direction, and (b) is applied in the short direction. It is a graph when doing. The relationship between the magnetic field and the resistance value when an external magnetic field is applied to the GMR element to which a large bias magnetic field is applied is shown. (A) is a graph when applied in the longitudinal direction, and (b) is the lateral direction. It is a graph when applying. It is the graph which showed the relationship between an applied magnetic field and the output of a magnetic sensor, (a) shows the case where an external magnetic field is applied to the X direction, (b) shows the case where an external magnetic field is applied to the Y direction. . It is the graph which showed the result of having measured the rotating magnetic field with the sensor chip package provided with the magnetic sensor in which the spiral GMR element was formed, (a) shows the relation between the rotation angle of an external magnet, and the output, (b ) Shows the relationship between the rotation angle of the external magnet and the angle error. 2 is a graph showing a result of measuring a rotating magnetic field with the sensor chip package shown in FIG. 1, wherein (a) shows the relationship between the rotation angle and output of the external magnet, and (b) shows the rotation angle and angle of the external magnet. The relationship with error is shown. It is the graph which showed the result of having measured the rotation magnetic field with the sensor chip package provided with the magnetic sensor to which a big bias magnetic field was applied, (a) shows the relation between the rotation angle of an external magnet, and the output, (b) The relationship between the rotation angle of an external magnet and an angle error is shown. It is the top view which showed the inside of the sensor chip package provided with the magnetic sensor which concerns on 2nd Embodiment of this invention. It is 14-14 sectional drawing of FIG. It is a bridge circuit of the magnetic sensor shown in FIG. 14 is a graph showing the relationship between the applied current of the sensor chip package shown in FIG. 13 and the output of the magnetic sensor, where (a) shows the case of a large applied current and (b) shows the case of a small applied current. Yes. It is the top view which showed the inside of the sensor chip package which concerns on the modification of 2nd Embodiment. It is 18-18 sectional drawing of FIG. 18 is a graph showing the relationship between the applied current of the sensor chip package shown in FIG. 17 and the output of the magnetic sensor. It is the top view which showed the current sensor provided with the full bridge circuit. It is the top view which showed the current sensor provided with the other full bridge circuit.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 and 2 show a sensor chip package 10 including a magnetic sensor 20 according to the first embodiment, and the magnetic sensor 20 is used as a rotation sensor. FIG. 1 is a plan view showing the main part inside the sensor chip package 10, and in the present embodiment, the front-rear and left-right directions will be described with reference to FIG.

  The sensor chip package 10 includes a package body 11 made of epoxy resin, a lead frame 12 installed from the inside of the package body 11 to the outside, a magnetic sensor 20 attached to the lead frame 12, and an inside and outside of the package body 11. And 8 lead frame terminals 13a to 13h, and 8 wires 14a to 14h for connecting the magnetic sensor 20 and the lead frame terminals 13a to 13h, respectively.

  The lead frame 12 is made of a conductor, such as copper, and has a square plate-like frame body 12a disposed in the center of the package body 11, and a projecting end extending from the front of the frame body 12a to the outside of the package body 11. It comprises a portion 12b and a projecting end portion 12c extending from the rear portion of the frame main body 12a to the outside of the package main body 11. The protruding end portions 12 b and 12 c are formed to support the lead frame 12 when epoxy resin is poured around the lead frame 12 and the lead frame 12 is fixed in the package body 11.

  The lead frame terminals 13 a to 13 h constitute connection terminals, and are made of copper like the lead frame 12. Four lead frame terminals 13 a to 13 h are arranged on the left and right sides of the package main body 11, and each of the lead frame terminals 13 a to 13 h extends from the outside to the inside of the package main body 11 and the frame main body 11 inside the package main body 11. It is comprised by the part extended in the direction along the peripheral part of 12a. The portions of the lead frame terminals 13a, 13d, 13e, and 13h located at the four corners along the peripheral edge of the frame main body 12a are each formed in a substantially L shape along the corner of the frame main body 12a. Further, the other lead frame terminals 13b, 13c, 13f, and 13g are formed in an I shape in which the central portion in the front-rear direction is located at the end of the left and right portions of the frame body 12a. ing.

  The magnetic sensor 20 is installed in the center portion of the frame body 12a and has the configuration shown in FIG. The magnetic sensor 20 includes an insulating substrate 21 installed on the upper surface of the frame main body 12a, GMR elements 22a to 22d formed on the upper and lower sides of the upper surface of the insulating substrate 21 in the center left and right direction and the center in the left and right direction, respectively. Eight electrodes 23a to 23h are formed at two corners on the upper surface of the insulating substrate 21, respectively. A bias magnet 24 is installed below the insulating substrate 21 on the lower surface of the frame body 12a.

  That is, the magnetic sensor 20 includes a portion on the side of the insulating substrate 21 installed on the upper surface of the frame body 12a and a bias magnet 24 installed on the lower surface of the frame body 12a. Are fixed to the frame body 12a by die bonding with their centers aligned with the center point O. The insulating substrate 21 is formed of a square plate-like body made of an insulating material such as silicon, glass, ceramic, etc. The length in the front-rear direction and the length in the left-right direction are each set to 1.8 mm, and the thickness is It is set to 0.4 mm. The insulating substrate 21 is installed on the upper surface of the frame body 12a so as to be positioned at the center of the package body 11 on the left and right and front and rear sides.

  The GMR elements 22a to 22d are composed of a linear granular thin film made of Ag—FeCo, and are formed on the surface of the insulating substrate 21 by being formed using a sputtering method. Of the GMR elements 22a to 22d, the GMR elements 22a and 22b are arranged symmetrically, and the GMR elements 22c and 22d are arranged symmetrically. That is, on the surface of the insulating substrate 21, the GMR elements 22 a and 22 b are positioned on the X axis when the direction extending through the center point O and extending in the left and right directions is the X axis and the direction extending in the front and rear directions is the Y axis. 22c and 22d are located on the Y axis. The GMR elements 22a to 22d are arranged at the same distance from the center point O, respectively.

  Each of the GMR elements 22a to 22d is formed in a linear shape having a plurality of folded portions. The GMR element 22a is disposed between the electrodes 23b and 23c, extends a certain length in a straight line from the right rear portion on the electrode 23b side to the left side, then turns back, and is spaced forward from the straight line described above. A linear thin film that extends to the right front side on the electrode 23c side after extending zigzag to the right and left at a distance from a line positioned at the rear, such as extending to the right side while maintaining the right side and extending to the left side. It consists of Both end portions of the GMR element 22a are connected to the electrodes 23b and 23c by the conductive portions 25b and 25c.

  Similarly, the GMR element 22b is arranged with the linear longitudinal direction facing the left-right direction, and both ends thereof are connected to the electrodes 23f, 23g by the conductive portions 25f, 25g. Further, the GMR elements 22c and 22d are arranged with the linear longitudinal direction facing the front-rear direction, and both ends of the GMR element 22c are connected to the electrodes 23d and 23e by the conductive parts 25d and 25e, and the GMR element 22d Both ends of are connected to electrodes 23a and 23h by conductive portions 25a and 25h. In the magnetic sensor 20, all end portions of the GMR elements 22 a to 22 d are located on the inner side of the insulating substrate 21.

The GMR elements 22a to 22d are formed using a sputtering apparatus (not shown). That is, a high voltage was applied between the insulating substrate 21 and the target made of Ag-FeCo while introducing argon gas into the vacuum chamber provided in the sputtering apparatus, and the ionized argon was collided with the target and was blown off. GMR elements 22a to 22d are formed by depositing a target material on the insulating substrate 21. The target in this case is a composite target in which an FeCo alloy is placed on an Ag target, thereby obtaining GMR elements 22a to 22d made of a granular thin film in which fine particles made of FeCo are dispersed in a parent phase made of Ag. It is done. In this case, Ag included in the GMR element 22a to 22d, Fe, the ratio of Co is the atomic composition _ratio, is set to approximately _{Ag 70 Fe 15 Co 15 atm%} .

  The electrodes 23a to 23h and the conductive portions 25a to 25h are each made of a thin copper plate. The electrodes 23a to 23h are connected to lead frame terminals 13a to 13h located in the vicinity by wire bonds via the wirings 14a to 14h, respectively. The GMR elements 22a and 22b are connected to the conductive portions 25b, 25c, 25f, and 25g, the electrodes 23b, 23c, 23f, and 23g, the wirings 14b, 14c, 14f, and 14g, and the lead frame terminals 13b, 13c, 13f, and 13g. The half-bridge circuit shown in FIG. 4A is formed by connecting them in series. Similarly, the GMR elements 22c and 22d are connected to the conductive portions 25a, 25d, 25e, and 25h, the electrodes 23a, 23d, 23e, and 23h, the wirings 14a, 14d, 14e, and 14h, and the lead frame terminals 13a, 13d, 13e, and 13h. Thus, the half bridge circuit shown in FIG. 4B is formed.

  A power supply voltage of 5V is supplied to the electrodes 23a and 23b from the lead frame terminals 13a and 13b, respectively. The electrodes 23e and 23g are grounded via lead frame terminals 13e and 13g, respectively. The electrodes 23c and 23f become output terminals via lead frame terminals 13c and 13f, respectively, and the electrodes 23d and 23h become output terminals via lead frame terminals 13d and 13h, respectively. The lead frame terminals 13c and 13f are connected via wiring (not shown), and an output signal Vx in the X-axis direction is taken out from the connection point. The lead frame terminals 13d and 13h are connected via wiring (not shown), and an output signal Vy in the Y-axis direction is taken out from the connection point.

  The bias magnet 24 is made of a disk-shaped ferrite magnet made of iron oxide as a main material, and has a diameter of 1.4 mm and a thickness of 0.35 mm. The bias magnet 24 is polarized with a plane that bisects the thickness direction as a boundary and is polarized in two directions perpendicular to the boundary surface, with the N pole on the upper side and the S pole on the lower side. . As a result, a magnetic field in the direction of the arrow in FIG. 3 is generated in the bias magnet 24, and a bias magnetic field along the longitudinal direction of each of the GMR elements 22a to 22d is directed from the center side of the insulating substrate 21 to the outside. Applied radially.

  Next, MR characteristics (magnetoresistance characteristics) of the GMR elements 22a to 22d included in the magnetic sensor 20 will be described. FIG. 5A shows the relationship between the magnitude of the magnetic field and the resistance value when an external magnetic field is applied in the longitudinal direction of each GMR element 22a to 22d, and FIG. 5B shows each GMR element 22a. The relationship between the magnitude | size of a magnetic field and resistance value when an external magnetic field is each applied to the transversal direction of -22d is shown. As can be seen from FIG. 5A and FIG. 5B, when the magnitude of the applied magnetic field is in the range of −4 kA / m or less or 4 kA / m or more, the longitudinal direction of each GMR element 22a to 22d is There is only a slight difference in the resistance value between when the external magnetic field is applied and when the external magnetic field is applied in the short direction of each of the GMR elements 22a to 22d, but the magnitude of the applied magnetic field is − In the range of about 4 kA / m to 4 kA / m, there is a clear difference in the change in both resistance values.

This can be explained from the MH characteristic shown in FIG. 6 (relation between the strength of the magnetic field and the magnitude of the magnetization) and the effective magnetic field shown below. FIG. 6 shows the MH characteristics of the GMR thin film having a thickness of 1000 mm and heat-treated at a temperature of 260 ° C. constituting each GMR element 22a to 22d. As can be seen from FIG. 6, in the GMR thin film constituting the GMR elements 22a to 22d, when the applied magnetic field is about −4 kA / m to 4 kA / m, the magnetic permeability represented by the slope of the MH curve is high. The value is 10 or more. When the magnetic permeability is high as described above, the magnetization of the GMR thin film constituting the GMR elements 22a to 22d by the external magnetic field is increased. The effective magnetic field is expressed by the following formula 1.
Heff (effective magnetic field) = Hex (external magnetic field) −Nd (demagnetizing field coefficient) × M (magnetization of magnetic body)

  Here, the demagnetizing field is a magnetic field in a direction opposite to the direction of magnetization generated in the magnetic body when the magnetic body is magnetized by an external magnetic field, and has an effect of weakening the magnetic field applied from the outside. The demagnetizing factor is “0” for poles and plates that are infinitely long, and is “1” for an infinitely thin plate. For this reason, if only the demagnetizing factor is taken into account, due to the shape anisotropy of the GMR elements 22a to 22d, the demagnetizing factor is smaller in the longitudinal direction of the GMR elements 22a to 22d than in the short direction. The effective magnetic field in the longitudinal direction of ˜22d is larger than the effective magnetic field in the short direction.

  If only the magnitude of the magnetization is taken into consideration, the longitudinal direction of the GMR elements 22a to 22d is within a range in which the GMR elements 22a to 22d having an applied magnetic field of about −4 kA / m to 4 kA / m have high permeability. Both the direction magnetization and the short direction magnetization increase. On the other hand, in the range where the magnitude of the applied magnetic field is −4 kA / m or less or 4 kA / m or more, the magnetic permeability is low, and the value is less than 10. For this reason, the change in magnetization with respect to the external magnetic field is reduced in both the longitudinal direction and the lateral direction of the GMR thin film.

  However, when both the demagnetizing factor and the magnitude of magnetization are affected, the GMR elements 22a to 22d having a magnitude of the applied magnetic field of about -4 kA / m to 4 kA / m have a high magnetization range in which the magnetic permeability is high. , The shorter direction of the GMR elements 22a to 22d is more susceptible to a demagnetizing field than the longer direction, and the effective magnetic field in the shorter direction of the GMR thin film is smaller than the effective magnetic field in the longer direction. In addition, when the magnitude of the applied magnetic field is in the range of −4 kA / m or less or 4 kA / m or more, the effect of the decrease in the magnetic permeability becomes large, and the change in the effective magnetic field with respect to the external magnetic field is the longitudinal direction and the short direction of the GMR thin film. So there will be no difference. As a result, even in the MR sensitivity of the GMR elements 22a to 22d, there is no difference between the longitudinal direction and the lateral direction.

  That is, when the absolute value of the value indicating the applied magnetic field is small, the magnetic permeability increases and the magnetization increases. At this time, the MR sensitivity between the longitudinal direction and the lateral direction of the GMR elements 22a to 22d is clearly different. However, if the absolute value of the value indicating the applied magnetic field is large, the magnetic permeability is small and the change in magnetization is small, and there is a clear difference in MR sensitivity between the longitudinal direction and the short direction of the GMR elements 22a to 22d. Will no longer occur. Accordingly, if a GMR thin film having a high magnetic permeability is used, magnetic field sensitivity anisotropy due to shape anisotropy can be obtained, but the difference in magnetic field sensitivity can be obtained only when the applied magnetic field is about -4 kA / m to 4 kA / m. However, this is not practical as it is.

  For this reason, in the magnetic sensor 20, the anisotropy of sensitivity is obtained in a wide magnetic field range by combining the bias magnet 24 with the GMR elements 22a to 22d. When a bias magnetic field from the bias magnet 24 is applied to each of the GMR elements 22a to 22d, the MR characteristics are as shown in FIGS. 7 (a) and 7 (b). In this case, the magnitude of the bias magnetic field by the bias magnet 24 is approximately 14 kA / m. FIG. 7A shows the relationship between the magnitude of the magnetic field and the resistance value when a magnetic field is applied in the longitudinal direction (left-right direction) of the GMR element 22a, and FIG. 7B shows the short circuit of the GMR element 22a. The relationship between the magnitude | size of a magnetic field and resistance value when a magnetic field is applied to a hand direction (front-back direction) is shown.

  As can be seen from FIG. 7A, the curve representing the MR characteristics when an external magnetic field is applied in the longitudinal direction of the GMR element 22a is the MR characteristics when the bias magnetic field shown in FIG. 5A is not applied. Compared with the curve representing, the asymmetric curve is shifted by the magnetic field intensity corresponding to the value of the bias magnetic field. As a result, the curve representing the MR characteristics shown in FIG. 7A becomes a substantially linear curve when the magnitude of the applied magnetic field is in the range of about −16 kA / m to 14 kA / m, From this curve, not only the magnitude of the magnetic field but also the polarity of the magnetic field can be discriminated.

  The MR ratio, which is the ratio between the resistance value when an external magnetic field is applied and the resistance value when no external magnetic field is applied, was 3.8% in the absence of a bias magnetic field, whereas When a bias magnetic field was applied, it was 5.6%. The MR ratio is proportional to the amount of deviation between the curve shown in FIG. 5A and the curve shown in FIG. 7A, and increases as the bias magnetic field increases. For this reason, by increasing the bias magnetic field, the curve shown in FIG. 5A moves further from the position of the curve shown in FIG. Further, the coercive force Hc corresponding to the magnetic field when the magnetization magnitude M is 0 was 0.32 kA / m when there was no bias magnetic field, but 0 kA / m when the bias magnetic field was applied. m.

  The coercive force Hc decreases when the magnitude of the magnetic field in the curves shown in FIGS. 5A and 5B and FIGS. 7A and 7B increases from the smaller one and from the larger one. 5 (a) and 5 (b), two curves are shown, while FIGS. 7 (a) and 7 (b) show one curve. Only shown. From this, it can be seen that the hysteresis of the resistance change with respect to the external magnetic field is clearly reduced by applying the bias magnetic field. That is, by applying a bias magnetic field, the energy in the magnetic field space stored when the magnetic field is increased comes out as it is when the magnetic field is decreased, and the energy loss is reduced.

  Further, as can be seen from FIG. 7B, the curve representing the MR characteristics when an external magnetic field is applied in the short direction of the GMR element 22a is the MR when the bias magnetic field shown in FIG. 5B is not applied. Compared with the curve representing the characteristic, the curve shows the characteristic in which the low sensitivity region of the MR characteristic with respect to the external magnetic field is widened. In this case, the state of being symmetric with respect to the magnetic field direction was maintained with the applied magnetic field being 0 kA / m. Thus, by applying a bias magnetic field, the sensitivity anisotropy between the longitudinal direction and the lateral direction of the GMR element 22a is clearly increased.

  As another example, MR characteristics of the GMR elements 22a to 22d were measured using SmCo bias magnets having a bias magnetic field larger than that of the bias magnet 24 instead of the bias magnet 24 described above. The results are shown in FIGS. 8 (a) and 8 (b). In this case, the magnitude of the bias magnetic field by the bias magnet was 50 kA / m. 8A shows the relationship between the magnitude of the magnetic field and the resistance value when a magnetic field is applied in the longitudinal direction of the GMR element 22a, and FIG. 8B shows the magnetic field in the short direction of the GMR element 22a. The relationship between the magnitude | size of a magnetic field when resistance is applied and resistance value is shown.

  As can be seen from FIG. 8A, when an external magnetic field is applied in the longitudinal direction of the GMR element 22a, no peak is seen in the curve representing the MR characteristics as compared to the case shown in FIG. The curve representing the characteristics is close to a straight line. This is because the value of the bias magnetic field exceeds the range of the measurement magnetic field, and according to this, a wide operating magnetic field range can be obtained. Further, as can be seen from FIG. 8B, when an external magnetic field is applied in the short direction of the GMR element 22a, there is a low sensitivity region of MR characteristics with respect to the external magnetic field compared to the case shown in FIG. Spread further. Thus, by increasing the bias magnetic field, the sensitivity anisotropy between the longitudinal direction and the lateral direction of the GMR element 22a is further increased.

  When the GMR elements 22a to 22d are operated by applying a bias magnetic field, the magnitude and direction of the actual operating magnetic field with respect to the external magnetic field become a combined vector of the magnitude and direction of the bias magnetic field and the external magnetic field, Calculated from the sum. Therefore, by increasing the bias magnetic field, a curve indicating the relationship between the magnitude of the magnetic field and the resistance value when the magnetic field is applied in the longitudinal direction of the GMR elements 22a to 22d and the magnetic field in the short direction of the GMR elements 22a to 22d. Both of the curves showing the relationship between the magnitude of the magnetic field and the resistance value when the voltage is applied are more influenced by the bias magnetic field and become closer to a straight line.

  From this result, by applying a bias magnetic field in the longitudinal direction of the GMR elements 22a to 22d, the MR characteristics with respect to the external magnetic field in the longitudinal direction of the GMR elements 22a to 22d become asymmetric with respect to the polarity of the magnetic field. It can be seen that positive and negative polarities can be detected and sensitivity anisotropy due to the shapes of the GMR elements 22a to 22d can be increased. Further, the MR characteristics of the GMR elements 22a to 22d with respect to the external magnetic field in the short direction extend the low sensitivity region up to the magnetic field exceeding the high permeability region. Thus, by applying a bias magnetic field, sensitivity anisotropy increases and hysteresis decreases.

  Next, the output of the magnetic sensor 20 when an external magnetic field from an external magnet (not shown) provided on the rotating body is applied to the surface side of the magnetic sensor 20 will be described. FIG. 9A shows the output Vx in the X-axis direction and the output Vy in the Y-axis direction of each half-bridge circuit when an external magnetic field in the X-axis direction (left-right direction) is applied to the magnetic sensor 20. FIG. 9B shows the output Vx in the X-axis direction and the output Vy in the Y-axis direction of each half-bridge circuit when an external magnetic field in the Y-axis direction (front-rear direction) is applied to the magnetic sensor 20. Yes.

The resistance value of the GMR element 22a shown in FIG. 4A is Rx1, the resistance value of the GMR element 22b is Rx2, the resistance value of the GMR element 22d shown in FIG. 4B is Ry1, and the resistance value of the GMR element 22c. When the value is Ry2, the output Vx and the output Vy are expressed by the following expressions 2 and 3, respectively.
Vx = Vcc × Rx2 / (Rx1 + Rx2)... Formula 2
Vy = Vcc × Ry2 / (Ry1 + Ry2) Equation 3

  In each half-bridge circuit, when an external magnetic field is applied in the longitudinal direction of the GMR elements 22a to 22d (the X-axis direction in FIG. 9A and the Y-axis direction in FIG. 9B), The nonlinear characteristics (the tendency of increased sensitivity and decreased sensitivity due to changes in magnetic field strength) of each GMR element 22a, 22b or GMR element 22c, 22d are canceled out, and the output Vx in FIG. 9A and the output Vy in FIG. As shown in the figure, output characteristics close to a slanting straight line were obtained.

  Further, when an external magnetic field is applied in the short direction of the GMR elements 22a to 22d (the Y-axis direction in FIG. 9A and the X-axis direction in FIG. 9B), the GMR elements 22a to 22A against the external magnetic field are applied. The resistance change of 22d is small, and the changed parts are canceled out to become almost insensitive characteristics. For this reason, output characteristics that are linear without change, such as the output Vy of FIG. 9A and the output Vx of FIG. 9B, were obtained. From this result, when an external magnetic field is applied in the longitudinal direction of the GMR elements 22a to 22d, the magnitude of the external magnetic field and the positive and negative polarities are detected based on the resistance values generated in the GMR elements 22a to 22d. It can be seen that accurate detection can be performed.

  When the direction of the external magnetic field is changed from the X-axis direction to the Y-axis direction, the curve representing the output Vx shows that the output Vx is large when the applied magnetic field is small and the applied magnetic field is large, as shown in FIG. The state changes from the state in which the output Vx becomes small to the state in which the output Vx becomes substantially constant regardless of the magnitude of the applied magnetic field in FIG. At that time, the curve representing the output Vy is output when the applied magnetic field in FIG. 9B is small from the state in which the output Vy is substantially constant regardless of the magnitude of the applied magnetic field in FIG. When Vy is small and the applied magnetic field is large, the output Vy is increased.

  Therefore, when the direction of the external magnetic field is an intermediate angle between the longitudinal direction and the short direction of the GMR elements 22a to 22d (there may be 45 degrees on the right and 45 degrees on the left), the output Vx is The inclination angle of the curve representing the output and the curve representing the output Vy is the same. In this case, both the curve representing the output Vx and the curve representing the output Vy have the same accuracy in detecting the magnitude of the external magnetic field and the positive / negative polarity. In other cases, when an external magnetic field is applied to the GMR elements 22a to 22d, the magnitude and direction of the external magnetic field are detected based on the resistance values generated in the GMR elements 22a to 22d. Good detection.

  Next, as a comparative example, a sensor chip package including a magnetic sensor in which four GMR elements without shape anisotropy formed in a spiral shape instead of the GMR elements 22a to 22d are prepared. A comparison test was performed with the package 10 and a sensor chip package including a magnetic sensor to which an SmCo bias magnet was attached. In this comparative test, an external magnet was installed on the rotating shaft, and the sensor chip package 10 and the like were installed at a predetermined position with the magnetic sensor 20 and the like facing the external magnet. In this case, the center of the magnetic sensor 20 or the like was aligned with the center of the external magnet. Further, the distance between each magnetic sensor 20 and the external magnet was adjusted so that a magnetic field strength of about 10 kA / m was obtained for each magnetic sensor 20 and the like.

  The reference for the rotation angle of the external magnet is that the direction of the external magnetic field is “0” in the direction of the arrow shown on the GMR element 22a of the magnetic sensor 20 in the state shown in FIG. The relationship between the output and angle of each half-bridge circuit in each X-axis and Y-axis direction was determined for an angle of every 10 degrees within a range of 360 degrees with the clockwise direction being positive. The outputs Vx and Vy, which are the midpoint potentials of the half-bridge circuits, are 2.5 V, which is half of the applied voltage 5 V, originally from the equivalent circuit, but the resistances of the GMR elements 22a and the like vary, and each GMR Since the resistance change due to the magnetic field of the element 22a and the like is small, the outputs Vx and Vy, which are the output potentials of the sensor chip packages with respect to the applied voltage when there is no external magnetic field, are measured in advance, and the values are used as reference voltages.

  The relationship between the differences ΔVx and ΔVy obtained by subtracting the reference voltage from the outputs Vx and Vy is shown in FIGS. 10 (a), 11 (a), and 12 (a). That is, when the external magnetic field from the external magnet changes due to the rotation of the rotating body, the outputs Vx and Vy output from the two half-bridge circuits change periodically. Then, a cosine wave and a sine wave having a phase difference are obtained from the change between the output Vx and the output Vy, and thereby the rotation direction, rotation speed, and rotation angle of the rotating body are detected. Focusing only on the influence of the external magnetic field by subtracting the reference voltage.

Further, based on the results shown in FIG. 10A, FIG. 11A, and FIG. 12A, the angle error Δθ is obtained from the following equation 4, and the relationship with the external parallel magnetic field rotation angle is shown in FIG. This is shown in (b), FIG. 11 (b), and FIG. 12 (b).
Δθ = ARCTAAN (ΔVy / ΔVx) −external parallel rotation angle Equation 4
That is, if one half-bridge circuit is a COS bridge and its output is Vx, and the other half-bridge circuit is a SIN bridge and its output is Vy, the rotation angle signal θ is obtained by performing an arctangent operation on the ratio of these. It is done. Equation 4 obtains the angle error Δθ by subtracting the value of the external parallel rotation angle (rotation angle of the external magnet) from the value obtained by calculating the arctangent of the ratio of the differences ΔVx and ΔVy.

  10A and 10B show measurement results of a sensor chip package including a magnetic sensor in which four GMR elements formed in a spiral shape are formed, and FIGS. 11A and 11B show the sensor. The measurement results of the chip package 10 are shown, and FIGS. 12A and 12B show the measurement results of the sensor chip package including the magnetic sensor to which the SmCo-based bias magnet is attached. That is, the spiral-shaped GMR element has no shape anisotropy, and the magnetic sensor to which the SmCo-based bias magnet is attached has a large bias magnetic field, and sensitivity anisotropy is sequentially applied from FIG. 10 to FIG. Has come to increase.

  As can be seen from FIGS. 10A, 11A, and 12A, as the sensitivity anisotropy of the magnetic sensor increases, the differences ΔVx and ΔVy between the outputs Vx and Vy are a triangular wave and a sine wave. The waveform changes from a waveform close to the middle to a waveform close to a smooth sine wave. As can be seen from FIGS. 10B, 11B, and 12B, as the sensitivity anisotropy of the magnetic sensor increases, the angle error Δθ has an absolute value of ± 3 degrees or more. From the range, it decreases to ± 2 degrees or less, and further to ± 1 degree or less. From this result, it is understood that the accuracy of detection of the rotation angle of the rotating body is improved by giving the GMR element shape anisotropy and further increasing the bias magnetic field.

  As described above, in the magnetic sensor 20 according to the present embodiment, the GMR elements 22a to 22d are formed of linear granular thin films extending while being folded back between one side and the other side. As a result, the GMR elements 22a to 22d have shape anisotropy in the longitudinal direction in which the linear shape extends and the short direction perpendicular to the longitudinal direction, and increase the output of the magnetic sensor 20. Can do. Further, by applying a bias magnetic field by the bias magnet 24 in the longitudinal direction in which the GMR elements 22a to 22d extend, the GMR elements 22a to 22d are magnetized to be close to saturation, thereby increasing the demagnetizing effect and increasing the shape anisotropy of the sensitivity. Can be made. Accordingly, the magnetic sensor 20 has excellent sensitivity anisotropy and can detect polarity.

(Second Embodiment)
13 and 14 show a sensor chip package 30 including a magnetic sensor 40 according to the second embodiment of the present invention, and the magnetic sensor 40 is used as a current sensor. FIG. 13 is a plan view showing the main part inside the sensor chip package 30. Hereinafter, in the present embodiment, the front-rear and left-right directions will be described with reference to FIG. The sensor chip package 30 is installed across a package body 31 made of epoxy resin, a lead frame 32 passing through the package body 31, a magnetic sensor 40 attached to the lead frame 32, and the inside and outside of the package body 31. 6 lead frame terminals 33a to 33f, and four wirings 34a to 34d for connecting the magnetic sensor 40 and the lead frame terminals 33b to 33e, respectively.

  The lead frame 32 is made of copper, extends from the outside, enters the package body 31 from the left front side of the package body 31, extends in a U shape so that the rear side is convex, and then the package body 31 It extends outward from the right side. Further, the U-shaped frame body 32a of the lead frame 32 has a larger width than the other portions, and the width of the gap formed inside the U-shape is reduced. In the lead frame 32, current flows from the measurement current terminal 32b side at the left end through the frame body 32a to the measurement current terminal 32c side at the right end, and the magnetic sensor 40 detects this current.

  The lead frame terminals 33 a to 33 f constitute connection terminals and, like the lead frame 32, are made of a conductor made of copper. The six lead frame terminals 33 a to 33 f are arranged on the left and right sides of the package main body 31, respectively, and each of the six lead frame terminals 33 a to 33 f extends to the left and right from the outside of the package main body 31 to the inside. And a portion extending in the front-rear direction. The lead frame terminals 33c and 33d arranged on the left and right of the front side are formed in an L shape in which the portions extending in the front-rear direction from the ends of the portions extending in the left-right direction extend in the rear direction. It is arrange | positioned slightly from the center of the front part side.

  Among the lead frame terminals 33a to 33f, the lead frame terminals 33b and 33e arranged on the left and right of the center in the front-rear direction are respectively T-shaped in which the center in the front-rear direction of the part extending in the front-rear direction is located at the end of the part extending in the left-right direction. Is formed. Further, the lead frame terminals 33a and 33f arranged on the left and right sides of the rear side of the package main body 31 are formed in an L shape in which the portions extending in the front-rear direction from the end portions of the portions extending in the left and right directions extend forward. The three lead frame terminals 33a to 33c and the lead frame terminals 33d to 33f arranged on the left and right are respectively arranged with a part extending left and right and a part extending front and rear at equal intervals.

  The magnetic sensor 40 is installed in the center portion of the frame body 32a in the front-rear direction, and is formed on each of the insulating substrate 41 installed on the upper surface of the frame body 32a and the left and right of the center in the front-rear direction on the upper surface of the insulating substrate 41. And a pair of GMR elements 42a and 42b, and electrodes 43a to 43d formed at four corners on the upper surface of the insulating substrate 41, respectively. A bias magnet 44 is installed below the insulating substrate 41 on the lower surface of the frame body 32a. The magnetic sensor 40 includes an insulating substrate 41 side portion installed on the upper surface of the frame body 32a, and a bias magnet 44 installed on the lower surface of the frame body 32a. The insulating substrate 41 and the bias magnet 44 are: Each is fixed to the frame body 32a by die bonding.

  The insulating substrate 41 is formed of a rectangular plate-like body that is longer in the left and right directions than the front and rear, which are made of the same insulating material as the insulating substrate 21 described above. .8 mm and thickness is set to 0.25 mm. The insulating substrate 41 is installed on the upper surface of the frame main body 32 a so as to be positioned at the left and right and front and rear centers of the package main body 31. The GMR elements 42a and 42b are made of the same material as the GMR elements 22a to 22d described above, and are formed on the surface of the insulating substrate 41 by using the sputtering method described above. . Further, the GMR elements 42 a and 42 b are arranged with their longitudinal directions facing left and right, and both linear ends facing the left and right outer sides of the insulating substrate 41.

  The electrodes 43a to 43d are each made of a thin copper plate, the electrodes 43a and 43b are respectively connected to the end portions of the GMR element 42a, and the electrodes 43c and 43d are respectively connected to the end portions of the GMR element 42b. The electrodes 43a to 43d are connected to the four lead frame terminals 33b to 33d located on the front side of the six lead frame terminals 33a to 33f, respectively, by wire bonding via the wirings 34a to 34d. ing. The GMR elements 42a and 42b are connected in series via the electrodes 43a to 43d, the wirings 34a to 34d, and the lead frame terminals 33b to 33e, thereby forming the half bridge circuit shown in FIG. Yes.

  A power supply voltage of 5 V is supplied to the electrode 43a from the lead frame terminal 33b through the wiring 34a. The electrode 43d is grounded via the wiring 34d and the lead frame terminal 33e. The electrodes 43b and 43c serve as output terminals via the wirings 34b and 34c and the lead frame terminals 33c and 33d, respectively. The lead frame terminals 33c and 33d are connected via wiring (not shown), and the output V is taken out as a signal from the connection point. This output V is obtained in the same manner as Vx and Vy in the above-described equations 2 and 3.

  The bias magnet 44 is made of a square plate-shaped ferrite magnet made of iron oxide as a main material, and the length in the front-rear direction is set to 1.1 mm, the length in the left-right direction is set to 2.4 mm, and the thickness is set to 0.2 mm. Has been. The bias magnet 44 is polarized with a plane that bisects the left and right sides as a boundary and is magnetized in a direction perpendicular to the boundary surface. The left side is an N pole and the right side is an S pole. As a result, a magnetic field in the direction of the arrow shown in FIG. 13 is generated in the bias magnet 44, and a bias magnetic field along the longitudinal direction is applied to each of the GMR elements 42a and 42b. The MR characteristics of the GMR elements 42a and 42b included in the magnetic sensor 40 are substantially the same as the MR characteristics of the GMR elements 22a to 22d included in the magnetic sensor 20 described above, and when a bias magnetic field is not applied, FIG. ) And FIG. 5B appear, and when a bias magnetic field is applied, the MR characteristics shown in FIG. 7A and FIG. 7B appear.

  Next, the relationship between the applied current and the output of the magnetic sensor 40 when a current is applied between the measurement current terminals 32b and 32c of the lead frame 32 in the sensor chip package 30 will be described. When a current directed from the measurement current terminal 32b to the measurement current terminal 32c is applied to the lead frame 32, a portion of the frame main body 32a corresponding to the GMR element 42a is in a state where the cross section of the frame main body 32a is viewed from the front. An external magnetic field is generated in the clockwise direction, and an external magnetic field is generated in a portion corresponding to the GMR element 42b in the frame body 32a in a counterclockwise direction when the cross section of the frame body 32a is viewed from the front. That is, an external magnetic field in the opposite direction along the longitudinal direction is applied to the GMR elements 42a and 42b.

  At this time, since the magnitude and direction of the magnetic field applied to the GMR elements 42a and 42b are a combined vector of the magnitude and direction of the bias magnetic field and the external magnetic field, the magnitude of the magnetic field applied to the GMR element 42a is larger than the bias magnetic field. The magnitude of the magnetic field applied to the GMR element 42b becomes smaller than the bias magnetic field, and the magnitude of the magnetic field applied to the GMR element 42b becomes smaller. In this case, the resistance value of the GMR element 42a is smaller than the resistance value of the GMR element 42b. Further, the output of the magnetic sensor 40 with respect to the applied current becomes the output V of the half bridge shown in FIG. 15, and this output V changes according to the magnitude of the applied current.

  FIG. 16A and FIG. 16B show the relationship between the magnitude of the current applied to the lead frame 32 and the output of the magnetic sensor 40. In this case, the magnitude of the bias magnetic field by the bias magnet 44 is 14 kA / m. According to the magnetic sensor 40, the output value extends linearly regardless of the positive or negative direction of the current value, and a good detection value can be obtained for a wide operating magnetic field. Further, as shown in FIG. 16B, stable output characteristics were obtained even when the applied current was small. From this, it can be seen that the magnetic sensor 40 is not easily affected by the fluctuation of the stray magnetic field. As described above, according to the magnetic sensor 40, there is no output fluctuation due to the stray magnetic field from the outside, and in particular, output characteristics excellent in detection of the magnetic field gradient in the bias magnetic field direction can be obtained.

(Modification)
17 and 18 show a sensor chip package 50 according to a modification of the sensor chip package 30 described above. In this sensor chip package 50, the width of the U-shaped frame body 52a of the lead frame 52 is smaller than the width of the frame body 32a described above, and accordingly, the inner side of the U-shaped portion of the frame body 52a. The width of the gap formed in the is increased. And in the part in which the magnetic sensor 40a is located on both the left and right sides of the frame main body 52a, lead-in portions 52b and 52c extending toward the center side of the magnetic sensor 40a are formed. The length between the leading ends of the drawing-in portions 52b and 52c is substantially the same as the width of the gap formed inside the frame main body 32a. The rest of the configuration of the sensor chip package 50 is the same as that of the sensor chip package 30 described above. Accordingly, the same parts are denoted by the same reference numerals and the description thereof is omitted.

  The sensor chip package 50 can have a higher current density than the frame main body 32a of the sensor chip package 30 by reducing the width of the frame main body 52a. As a result, as shown in FIG. 19, the output of the magnetic sensor 40a when the same current is applied can be increased as compared with the sensor chip package 30 described above. For example, when the applied current is 1 amp, the output of the magnetic sensor 40a is about 1.7 mV as shown in FIG. 19, but the output of the magnetic sensor 20 of the sensor chip package 30 is as shown in FIG. ) As shown in FIG. Thus, the magnetic sensor 40a can be made highly sensitive by reducing the width of the frame body 52a.

  Further, in the sensor chip package 50, even if the lead-in portions 52b and 52c are not provided, the same effect as that in the case where the lead-in portions 52b and 52c are provided is obtained. As the area is reduced, die bonding of the insulating substrate 41 to the frame main body 52a becomes difficult. Further, when a large current is passed through the lead frame 52, heat is generated from the lead frame 52 due to Joule loss. However, providing the lead-in portions 52b and 52c also has an effect of diffusing the heat. For this reason, in the sensor chip package 50, lead-in portions 52b and 52c are provided in the lead frame 52.

  The magnetic sensor according to the present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications within the technical scope of the present invention. For example, in each of the embodiments described above, the bias magnets 24 and 44 are used as the bias magnetic field applying means, but instead of this, a magnetic coil may be used and a bias magnetic field may be generated by passing a current through the magnetic coil. Good. In each of the embodiments described above, the bridge circuit is a half bridge circuit, but a full bridge circuit may be used. For example, in the embodiment using the magnetic sensors 40 and 40a as current sensors, the full bridge circuit shown in FIGS. 20 and 21 can be used.

  FIG. 20 shows a full bridge circuit including GMR elements 62a to 62d, electrodes 63a to 63h, and conductive portions 65a to 65e. FIG. 21 shows a full bridge circuit including GMR elements 72a to 72d, electrodes 73a to 73h, and conductive portions 75a to 75d. The GMR elements 72a and 72b and the GMR elements 72c and 72d are linear. By arranging them in parallel, they are nested. In addition, other portions of the magnetic sensor according to the present invention can be implemented with appropriate modifications.

  20, 40, 40a ... magnetic sensor, 21, 41 ... insulating substrate, 22a-22d, 42a, 42b, 62a-62d, 72a-72d ... GMR element, 24, 44 ... bias magnet.

Claims (5)

An insulating substrate;
A GMR element formed of a linear high permeability granular thin film formed on the surface of the insulating substrate and extending between the one side and the other side;
A magnetic sensor, comprising: a bias magnetic field applying unit that is disposed in the vicinity of the insulating substrate and applies a bias magnetic field in a longitudinal direction in which the linear shape of the GMR element extends.   The magnetic sensor according to claim 1, wherein the granular thin film constituting the GMR element is configured by dispersing fine particles made of FeCo in a matrix phase made of Ag.   The magnitude | size of the said external magnetic field and a positive / negative polarity are detected based on the resistance value which generate | occur | produces in the said GMR element when an external magnetic field is applied to the longitudinal direction where the linear form of the said GMR element extends. Magnetic sensor.   The bias magnetic field applying means is composed of a bias magnet disposed facing the insulating substrate in a state where the magnetic center of the magnetic pole surface is aligned with the center of the insulating substrate, and the GMR element is arranged at the center of the insulating substrate. It is composed of four elements formed at the same distance from the center point along two axes that are orthogonal to each other and extend in parallel to the magnetic pole surface, and are provided along each of the two axes. Two GMR elements are connected in series to form two bridge circuits, and a power supply voltage is applied to both ends of the two bridge circuits so that output signals are taken out from the connection points of the two GMR elements, respectively. The magnetic sensor according to claim 1.   The bias magnetic field applying means is composed of a bias magnet magnetized in two poles along the back surface of the insulating substrate, and the GMR element is disposed at a portion corresponding to both poles of the bias magnet on the surface of the insulating substrate. The two GMR elements are formed in series, and the two GMR elements are connected in series to form a bridge circuit. A power supply voltage is applied to both ends of the bridge circuit, and output signals are respectively output from the connection points of the GMR elements. The magnetic sensor according to claim 1, wherein the magnetic sensor is taken out.

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