JP2009236803A - Magnet impedance sensor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnet impedance sensor element of low profile for attaining Z-axis compactness and thinning of a three-dimensional magnetometric sensor. <P>SOLUTION: The magnet impedance sensor element 1 for the Z-axis has a substrate 11 made of a nonmagnetic material; a magnetic amorphous wire; a magnetic amorphous wire coating insulator and a detection coil 3 formed around the magnetic amorphous wire coating insulator; and a rectangular element insulator covering these parts and has an electrode terminal on the end face of the element insulator. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magneto-impedance sensor element (hereinafter referred to as an MI element) incorporating an amorphous wire used in a magnetic sensor, particularly a Z-axis MI element orthogonal to a plane composed of an X axis and a Y axis in a three-dimensional magnetic sensor. Related to miniaturization of

As a conventional MI element structure, there is a bobbin type element in which an amorphous wire is fixed at the center of a substrate and a detection coil is wound around the substrate (Patent Document 1, Patent Document 2, etc.).
Since the amorphous wire that is the magnetic core of the MI element is crystallized by soldering by heating, electrical coupling is performed between the both ends of the amorphous wire and the electrode by ultrasonic bonding or the like.
In addition, since the magnetic properties of the amorphous wire are easily affected by distortion due to external stress, the amorphous wire is covered with a gel material.
JP 2000-81471 A JP 2001-296127 A

As another MI element structure, the extending groove is cut in a certain direction of the substrate, the amorphous wire, the insulator and the first detecting coil part are embedded in the extending groove, and the second detecting coil part is provided on the upper surface of the groove. There is a grooved MI element to be formed (Patent Document 3).
Republished patent WO2003 / 071299

Further, as a structure of the MI element, a thin film type MI element in which a thin film magnetic core is provided on a substrate without using an amorphous wire has been proposed (Patent Document 4, Patent Document 5, etc.).
JP 2000-292506 A JP 2002-270918 A

However, the conventional MI element has the following problems.
This bobbin-type MI element is not suitable for miniaturization because an amorphous wire is arranged on a substrate and covered with a substance on a gel, and electrical coupling is made between the both ends of the amorphous wire and electrodes by ultrasonic bonding. Therefore, since a long amorphous wire is required, the size cannot be reduced, and when it is used as a Z-axis MI element of a magnetic sensor, there is a problem that the height of the three-dimensional magnetic sensor increases because the height increases.
Further, since the groove type MI element performs an extension process on the substrate, there is a problem that the extension groove process is limited to a material having a good damage or a good machinability. Furthermore, as shown in FIG. 8 of Patent Document 3, it is difficult to reduce the height of the Z-axis MI element of the magnetic sensor.
Further, since the thin film type MI element has a planar structure suitable for a one-dimensional or two-dimensional magnetic sensor, when used as a Z-axis MI element of the magnetic sensor, the height is smaller than the groove type MI element. Is even more difficult.

  The present invention has been made in view of the above-described problems with respect to a Z-axis MI element incorporating an amorphous wire having an excellent magnetic impedance effect as a three-dimensional MI sensor. By reducing the size, it is intended to reduce the size and thickness of the three-dimensional MI sensor, to increase the degree of freedom in selecting the substrate material, and to increase the size of the substrate wafer.

The magneto-impedance sensor element of the present invention is formed so as to include a substrate made of a non-magnetic material, a magnetic amorphous wire held on the substrate and provided with a conductive pattern at both longitudinal ends thereof, and the magnetic amorphous wire. And a foil-like conductive plane pattern and a foil-like conductive three-dimensional pattern formed around the magnetic amorphous wire-covered insulator, and conductive patterns are provided at both ends thereof. A detection coil, a rectangular element insulator formed on the substrate so as to cover the magnetic amorphous wire, the magnetic amorphous wire-covered insulator and the detection coil; On the surface perpendicular to the axial direction of the magnetic amorphous wire, the conduction of the magnetic amorphous wire Characterized in that it has a turn and electrodes which extend respectively from said conductive pattern of said detection coil (claim 1).

As described above, on the substrate, the bulk magnetic amorphous wire (the cross-sectional shape is circular) is held on the substrate by the magnetic amorphous wire-covered insulator without applying stress to the magnetic amorphous wire. As a result, since no stress is applied to the magnetic amorphous wire in the planar structure, no stress distortion occurs, so that the magnetic impedance effect of the amorphous wire is not harmed.
Further, the outer peripheral surface of the magnetic amorphous wire is covered with a magnetic amorphous wire covering insulator. And the helical detection coil which consists of a foil-like electroconductive plane pattern and foil-like electroconductive solid pattern is formed in the circumference | surroundings of an insulator. Thereby, the output and sensitivity of the Z-axis MI element can be improved.

Further, a rectangular element insulator is formed on the substrate so as to cover the magnetic amorphous wire, the magnetic amorphous wire covering insulator, and the detection coil, and is orthogonal to the axial direction of the magnetic amorphous wire on the outer surface of the element insulator. Electrodes extending from the conductive pattern of the magnetic amorphous wire and the conductive pattern of the detection coil are formed on the surface. As a result, the magnetic amorphous wire, the magnetic amorphous wire-covered insulator and the detection coil on the substrate constituting the Z-axis MI element can be protected, and a rectangular flat surface having a certain thickness can be obtained. Bonding to the upper part of the Z-axis MI element at the time of manufacturing the three-dimensional sensor is enabled. Furthermore, the height of the Z-axis MI element can be reduced.

In the magneto-impedance sensor element of the above invention, the magnetic amorphous wire-wire-covered insulator is
A first insulator formed between the planar pattern and the magnetic amorphous wire;
A second insulator for fixing the magnetic amorphous wire to an upper surface of the first insulator;
A third insulator formed between the three-dimensional pattern and the magnetic amorphous wire;
Preferably, the second insulator is made of a liquid resin capable of fixing and fixing the magnetic amorphous wire on the planar pattern by surface tension.

That is, a straight amorphous wire is placed on the upper surface of the first insulator, and a liquid resin is dropped between the first insulator and the magnetic amorphous wire. The liquid resin wets between the magnetic amorphous wire and the first insulator in the longitudinal direction of the magnetic amorphous wire, and the magnetic amorphous wire is fixed on the upper surface of the first insulator by the surface tension of the liquid resin. Thereafter, when the liquid resin is cured, the magnetic amorphous wire is fixed to the upper surface of the first insulator.
In this way, the magnetic amorphous wire with a small diameter gets wet with the liquid, is fixed on the surface of the insulator formed on the substrate by the surface tension of the liquid, and is further dried and fixed as it is. It can be incorporated into the Z-axis MI element without applying any stress. Thereby, since the distortion to the magnetic amorphous wire due to the external stress generated when the magnetic amorphous wire is incorporated in the Z-axis MI element can be prevented, the decrease in the output and sensitivity of the Z-axis MI element can be eliminated.

In the magneto-impedance sensor element of the above invention, it is preferable that at least two magnetic amorphous wires are arranged in parallel, and the magnetic amorphous wires are electrically connected in series to each other ( Claim 3).

With this configuration, since the number of detection coils wound around the magnetic amorphous wire can be increased, the output and sensitivity can be improved without increasing the height of the Z-axis MI element.

Since the magneto-impedance sensor element of the present invention can reduce the height of the Z-axis MI element in the three-dimensional MI sensor, the three-dimensional MI sensor can be reduced in size, particularly reduced in thickness.
In addition, it is possible to arrange a magnetic amorphous wire having a small diameter on the detection coil pattern of the substrate in a state where no stress is applied by utilizing the surface tension. Thereby, the magneto-impedance sensor element omits the bulk magnetic amorphous wire, the insulator, and the extending groove (concave structure) for embedding the first detection coil portion in the substrate without impairing the magnetic impedance effect. be able to.
In addition, since there is no cutting for the extending groove, the possibility of damage to the substrate is eliminated. The problem of micro workability is solved and the choice of substrate material is expanded.

  The Z-axis MI element in the three-dimensional MI sensor of the present invention sequentially forms a magnetic amorphous wire insulator, a detection coil, an element insulator, and an electrode with a bulk magnetic amorphous wire as a core on a substrate by fine processing. It consists of a planar structure.

  Since the substrate does not require a concave extending groove, the substrate may be thin. However, since it is used for the Z-axis, it is preferable that the substrate has a certain thickness. For example, a substrate having a thickness of 0.1 mm to 0.5 mm can be used. If the thickness is less than 0.1 mm, it is difficult to form an amorphous wire, an insulator, and a detection coil with a planar structure on the substrate, and it is also difficult to assemble a three-dimensional sensor for the Z axis. If it exceeds 0.5 mm, the MI element cannot be miniaturized. When a silicon wafer is used, a thickness of 0.25 mm to 0.35 mm is preferable from the viewpoint of the size and thinning of the silicon wafer.

Further, since the cutting process for forming the extending groove on the substrate is not required and the substrate material is not limited, insulating alumina ceramics, semiconductor silicon wafers, conductor metals, and the like can be used. Further, in the case of a silicon wafer for use as a substrate, the size can be from 6 inches to 12 inches in diameter.

The bulk magnetic amorphous wire used for the Z-axis MI element is a zero magnetostrictive amorphous wire that can exhibit the MI effect. Since it is preferable that the MI sensor has no hysteresis, the diameter of the magnetic amorphous wire is preferably 20 μm or less.
This MI effect cannot be fully exerted when an external stress is applied to the magnetic amorphous wire, and the magnetic characteristics such as the linearity of the output voltage detected with respect to the strength of the magnetic field and the decrease in sensitivity are deteriorated.

Therefore, the magnetic amorphous wire-covered insulator containing the magnetic amorphous wire has a function of insulating the magnetic amorphous wire to which the excitation current is passed and the detection coil for detecting the strength of the magnetic field, and a small diameter and short magnetic amorphous wire. It is necessary to have a function of fixing the substrate on the substrate.
Here, the first insulator that electrically insulates the planar pattern constituting the lower part of the detection coil and the magnetic amorphous wire and the third insulator that covers the magnetic amorphous wire and the three-dimensional pattern constituting the upper part of the detection coil are: At least an electrical insulation function is required. Examples of the insulator include an inorganic insulating material such as aluminum oxide and silicon oxide, and an organic insulating material such as an epoxy resin.
The second insulator that fixes the magnetic amorphous wire to the upper surface of the first insulator needs to have both an electrical insulating function and a fixing function. As long as the insulator has both functions, an organic insulating material or an inorganic insulating material may be used.

A liquid epoxy resin is preferable as the organic insulating material having both functions. On the substrate, an insulating layer made of an insulator (which may be a SiO2 film by a CVD method or an epoxy resin film by a coating method) is formed on a planar pattern made of a plurality of conductor films constituting the lower part of the detection coil. Next, a straight amorphous wire is placed on the upper surface of the insulating layer in a state where no stress is applied, and a liquid epoxy resin whose wettability is improved by solvent dilution is dropped between the insulating layer and the amorphous wire. Then, the surface of the amorphous wire including the lower part of the amorphous wire and the insulating layer are wetted by the epoxy resin. Then, the surface tension acts between the insulating layer and the amorphous wire, and the amorphous wire remains in a straight state, and the amorphous wire affects the MI effect of the amorphous wire on the upper surface of the insulator, that is, the planar pattern of the substrate. Fixes only with surface tension without applying external stress.

Next, the magnetic amorphous wire fixed by the surface tension of the epoxy resin is left as it is or baked, so that the epoxy resin is cured and fixed on the substrate.
Thus, the magnetic amorphous wire having a diameter of 5 to 20 μm can be disposed on the planar pattern of the substrate without applying stress.

Furthermore, when a liquid resin utilizing surface tension is applied to a magnetic amorphous wire fixed on a flat pattern, an insulator is formed in a film shape along the shape of the outer peripheral surface of the magnetic amorphous wire. It is enclosed in a thin film insulator having a circumferential shape similar to the cross-sectional shape of the amorphous wire.

In addition, when a SiO2 film is formed on the outer peripheral surface of a magnetic amorphous wire fixed on a flat pattern by a CVD method, a film-like insulating layer is formed and a circumferential insulation similar to the cross-sectional shape of the magnetic amorphous wire is formed. Become a layer.
As a result, the detection coil formed on the outer peripheral surface of the insulator also has a circular shape, and the magnetic amorphous wire and the detection coil have a circular shape close to each other through the insulator, so that the detection sensitivity of the external magnetic field can be improved. .

Moreover, the insulation by a glass film can also be performed to part or all of the outer periphery of a magnetic amorphous wire. Thereby, the thickness of the circular insulator can be further reduced, and the detection sensitivity of the external magnetic field can be improved.

Furthermore, even if a magnetic amorphous wire having an insulating glass film is placed directly on a flat pattern, the insulating property is secured by glass between the two, so the magnetic amorphous wire is fixed and fixed on the flat pattern. For the function of the material, only the function of fixing is required. In other words, the present invention is not limited to an insulating material, and for fixing the magnetic amorphous wire on the plane pattern of the substrate without applying any external stress that affects the MI effect of the magnetic amorphous wire as described above. The flexibility of material selection is expanded.

Next, the detection coil has a foil-like conductive planar pattern composed of a plurality of ribbon-like conductor films constituting the lower part of the detection coil, and a foil-like conductive pattern consisting of a plurality of ribbon-like conductor films constituting the upper part of the detection coil. A conductive three-dimensional pattern. And a detection coil can be comprised combining the one coil part which consists of a plane pattern, and the other coil part which consists of a solid pattern which electrically connects the edge part of an adjacent plane pattern.
These ribbon-like conductor films can be formed with high accuracy by metal deposition, etching treatment, or the like. Therefore, a highly accurate detection coil is formed.

The element insulator is made of a rectangular insulating resin having a thickness of 0.10 to 0.20 mm so as to cover the magnetic amorphous wire on the substrate, the magnetic amorphous wire covering insulator, and the detection coil. Has been.
For bonding from the upper part of the Z-axis MI element, the bonding processing surface becomes small at a thickness of 0.10 mm or less, while when the thickness exceeds 0.20 mm, the size of the bonding processing surface is as follows: Not only is the protective film unnecessary, but it takes too much time to form the element insulator.

The flat surface of the element insulator perpendicular to the axial direction of the magnetic amorphous wire includes an electrode for the magnetic amorphous wire and an electrode for the detection coil. The electrode, the magnetic amorphous wire, and the electrode and the detection coil are electrically connected to each other. A conductive pattern is formed so as to be connected. The electrodes and the conductive pattern are formed on the outer surface of the element insulator by a method by metal vapor deposition or a method of removing the metal foil film (Cu plating) by etching.

(Example)
Examples of the planar MI element for Z-axis according to the present invention will be described with reference to FIGS. FIG. 1 is a conceptual diagram showing the front of the planar MI element 1, and FIG. 2 is a conceptual diagram showing a cross section taken along the line AA 'in FIG. 3 is a side view from the direction B of FIG. 1, and FIG. 4 is a side view from the direction C from FIG.

The substrate 11 is a nonmagnetic and insulating alumina substrate having a width of 0.7 mm, a thickness of 0.3 mm, and a length of 0.7 mm.
Here, when used as the Z-axis MI element of the three-dimensional MI sensor, the length of 0.7 mm is the height direction.

Two magnetic amorphous wires 2 having a diameter of 10 μm and a length of 0.48 mm made of a zero magnetostrictive amorphous CoFeSiB alloy are used. Each amorphous wire 2 is arranged in parallel on the upper surface of a first insulator 41 formed on the upper surface of a foil-like conductive flat pattern 31 composed of a plurality of ribbon-like conductor films.

The detection coil 3 includes a planar pattern 31 and a three-dimensional pattern 32 and is formed in a spiral shape.
In the planar pattern 31, seven ribbon-like conductor films having a width of 15 μm and a thickness of 2 μm are arranged on the flat surface of the substrate 11.

On the other hand, the three-dimensional pattern 32 is formed across the outer surface of the third insulator 43 formed so as to enclose the amorphous wire 2 and the surface of the planar pattern 31, and has seven conductive widths of 15 μm and thickness of 2 μm. Made of a ribbon-like conductor film.

That is, the planar pattern 31 and the three-dimensional pattern 32 are formed by forming laminated joint portions formed by joining the ends of the respective ribbon-like conductor films in a laminated state on both sides of the magnetic amorphous wire 2. 31 and the three-dimensional pattern 32 are integrally formed to form two spiral detection coils 3 each having 7 turns.

Here, the ribbon-like conductor film constituting the planar pattern 31 is formed on the flat surface of the substrate 11. It is formed by performing planar patterning of the lower coil, then copper plating, and removing the lower Ti / Cu seed layer by etching.
Further, the ribbon-like conductor film constituting the three-dimensional pattern 32 is subjected to three-dimensional patterning on the outer surface of the insulator 43 and the surface of the flat pattern 31, and then subjected to copper plating and etching to form an upper Ti / Cu seed. Formed by removing the layer.

The insulator 4 includes a first insulator 41 formed on the upper surface of the planar pattern 31 for insulation between the planar pattern 31 formed on the flat surface of the substrate piece 11 and the magnetic amorphous wire 2, and a first insulator A second insulator 42 for fixing the magnetic amorphous wire 2 on the upper surface, and a second so as to enclose the amorphous wire 2 for insulation between the magnetic amorphous wire 2 disposed on the upper surface of the second insulator 42 and the three-dimensional pattern 32. 3 insulators 43.

That is, after the planar pattern 31 is formed on the flat surface of the substrate 11, the first insulator 41 having a thickness of 2 μm is formed on the upper surface of the planar pattern 31 with a photosensitive epoxy resin.
Next, the magnetic amorphous wire 2 is placed straight on the upper surface of the first insulator 41 in the longitudinal direction, and the solvent diluted liquid which becomes the second insulator 42 is interposed between the first insulator 41 and the magnetic amorphous wire 2. An epoxy resin is dripped. The longitudinal direction along the gap between the surface of the magnetic amorphous wire 2 and the first insulator 41 gets wet with the epoxy resin, and the magnetic amorphous wire 2 is fixed to the upper surface of the first insulator 41 by the action of surface tension. After fixing, when the solvent-diluted epoxy resin is baked at 100 ° C. for about 30 minutes, the magnetic amorphous wire 2 is fixed to the upper surface of the first insulator 41 by the second insulator 42.

After the magnetic amorphous wire 2 is fixed to the upper surface of the first insulator, a third insulator 43 made of an insulating layer having a thickness of about 2 μm is formed of a photosensitive epoxy resin so as to enclose the magnetic amorphous wire 2. The third insulator 43 is formed into a film shape along the shape of the outer peripheral surface of the magnetic amorphous wire by applying a liquid resin utilizing surface tension. This insulator consists of a thin insulating layer having a circumferential shape similar to the cross-sectional shape of the magnetic amorphous wire.

Next, a ribbon-like conductor film is formed from the outer surface of the third insulator 43 to the surface of the planar pattern 31 as described above.
Then, the three-dimensional pattern 31 has many ring-shaped portions resembling the cross-sectional shape of the magnetic amorphous wire through the thin film third insulator 43.

After the detection coil is formed, a conductive pattern 60 for electrically connecting the magnetic amorphous wire 2 in series, a conductive pattern 60 for electrically connecting the detection coil 3 in series, and a later process. A conductive pattern 60 for electrically connecting the electrode 6 to be formed, the magnetic amorphous wire 2 and the detection coil 3 is formed by a method similar to the method for forming the planar pattern 31.

Next, a rectangular shape having a width of 0.7 mm, a length of 0.6 mm, and a thickness of 0.10 mm so as to cover the magnetic amorphous wire 2, the magnetic amorphous wire covering insulator 4, the detection coil 3, and the conductive pattern 60 on the substrate. An element insulator 5 made of an insulating resin is formed.

The electrodes 61 electrically connected to the two conductive patterns 60 on the substrate extended from the magnetic amorphous wire 2 and the two conductive patterns 60 on the substrate extended from the detection coil 3 are electrically connected. The connecting electrode 62 is formed on the flat surface in the length direction of the element insulator 4 by vapor deposition of copper metal having a thickness of 3 μm.

The size of the Z-axis MI element configured as described above is 0.7 mm in height, 0.7 mm in width, and 0.4 mm in thickness. Thereby, the height can be reduced to 0.7 mm, which is lower than the conventional groove type, and the three-dimensional MI sensor can be made thinner. Further, since the thickness is 0.4 mm, it is stable even when incorporated in a three-dimensional MI sensor, and an electrode width of 0.1 mm is sufficient for bonding during wiring.

Next, the characteristics of the Z-axis MI element of the present invention are evaluated and described with reference to FIGS.
Regarding the characteristics shown in FIG. 5, the rotation angle around the axis is defined on the horizontal axis, and the magnitude of the output signal of the magnetic sensor is defined on the vertical axis as 0 mV when the rotation angle is 0 °. FIG. 6 shows a circuit diagram of the Z-axis magnetic sensor.
A change in output signal is shown when a Z-axis magnetic sensor incorporating an MI element in the Z-axis direction and the amorphous wire 2 in the vertical direction on the XY plane is rotated 360 degrees around the X-axis. .

From FIG. 5, magnetic sensing in the Z-axis direction can be detected with high accuracy.
Therefore, by using the magnetic sensor incorporating the MI element of the present invention for the Z-axis of the three-axis magnetic sensor, the height of the Z-axis magnetic sensor can be reduced. Can be realized.

  Since the magneto-impedance sensor element according to the present invention can reduce the height of the three-dimensional magnetic sensor for the Z-axis, the three-dimensional magnetic sensor can be made thinner and smaller, so that it can be used for small electronic devices such as mobile phones. It can be applied to a small magnetic sensor.

It is a conceptual diagram which shows the front of the planar Z-axis MI element of this invention. It is a conceptual diagram which shows the cross section which follows the A-A 'line | wire of FIG. 1 in an Example. It is a conceptual diagram which shows the cross section of the B direction of FIG. 1 in an Example. It is a conceptual diagram which shows the surface of the C direction of FIG. 1 in an Example. It is a diagram which shows the characteristic in an Example. It is a circuit diagram in an example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Z-axis MI element 11 Board | substrate 2 Amorphous wire 3 Detection coil 31 Planar pattern 32 Three-dimensional pattern 4 Insulator 41 1st insulator 42 2nd insulator 43 3rd insulator 5 Element insulator 6 Terminal 60 Conductive pattern 61 Detection coil Terminal 62 Amorphous Wire Terminal

Claims (3)

A non-magnetic substrate;
A magnetic amorphous wire held on the substrate and provided with conductive patterns at both longitudinal ends thereof;
A magnetic amorphous wire-covered insulator formed to enclose the magnetic amorphous wire;
A detection coil having a foil-like conductive plane pattern and a foil-like conductive three-dimensional pattern formed around the magnetic amorphous wire-covered insulator, and provided with a conductive pattern at both ends thereof;
A rectangular element insulator formed on the substrate so as to cover the magnetic amorphous wire, the magnetic amorphous wire covering insulator, and the detection coil;
The element insulator has electrodes extending from the conductive pattern of the magnetic amorphous wire and the conductive pattern of the detection coil on a surface of the outer surface perpendicular to the axial direction of the magnetic amorphous wire. A magneto-impedance sensor element comprising: In Claim 1, the magnetic amorphous wire wire covering insulator is:
A first insulator formed between the planar pattern and the magnetic amorphous wire;
A second insulator for fixing the magnetic amorphous wire to an upper surface of the first insulator;
A third insulator formed between the three-dimensional pattern and the magnetic amorphous wire;
The magneto-impedance sensor element, wherein the second insulator is made of a liquid resin capable of fixing and fixing the magnetic amorphous wire on the planar pattern by surface tension. In Claim 1 or Claim 2,
A magneto-impedance sensor element, wherein at least two of the magnetic amorphous wires are arranged in parallel, and the magnetic amorphous wires are electrically connected to each other in series.

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