JPH083500B2 - Current detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In order to obtain a small-sized current detector applicable to both AC and DC, the present invention provides a current to a conductor layer adhered to a hole wall of a through hole close to a magnetoelectric conversion element. Is a current detector that simply detects the current value by the output of the magnetoelectric conversion element.

[Industrial applications]

The present invention relates to a detector that detects a current value by changing the strength of a magnetic field generated when a current flows.

Conventional current detectors often require dedicated ones for direct current and alternating current, and are relatively large. Especially for direct current, it is necessary to develop a small insulated current detector. Was requested.

[Conventional technology]

Conventionally, a detector that uses a transformer and a detector that uses a leakage sensor are generally used as detectors for measuring AC current, and a detector that uses a resistance element and a Hall effect element for detectors that measure DC current. What you use is commonly used.

An AC current detector using a transformer is difficult to miniaturize, and since the transformer has an inductance component, it is difficult to accurately measure a current having many high frequency components such as a pulse current. On the other hand, an AC current detector using a leak sensor has a drawback that it cannot be applied in a wide range because it requires a current core and an annular core having a size suitable for the current.

A DC current detector using a resistance element consumes unnecessary power in the resistance element, and it is necessary to select and use the current value and the resistance value of the resistance element and the DC potentiometer each time. If an unnecessary signal is mixed in the circuit, it has a drawback that it directly affects the measurement and cannot be downsized.

Further, the DC current detector using the Hall effect element has a drawback that the device becomes complicated and large in size because a means for removing the influence of the external magnetic field and the earth magnetism is required.

Japanese Patent Application filed by the applicant of the present application on April 9, 1987
No. 62-87749 is a current detector from which the above-mentioned drawbacks are removed, and FIG. 8 is a principle configuration diagram of the current detector.

In FIG. 8, the pair of magnetoelectric conversion elements 1 and 2 have the same characteristics and receive magnetic fields in the same but different directions with respect to the magnetic loop 5 generated when a current 4 flows through the conductor 3. Therefore, since the outputs extracted from the conversion elements 1 and 2 have opposite phases, when the synthesis section 6 performs differential synthesis, the synthesis section 6
Is almost twice as high as the output of the element alone.

On the other hand, when the external magnetic field 7 influences the whole of the current detector 8, the outputs of the magnetoelectric conversion elements 1 and 2 are in phase with the external magnetic field 7, and thus the output differentially combined in the combining unit 6 is: The output signal from the external magnetic field 7 is canceled.

[Problems to be solved by the invention]

In the current detector 8, the conducting wire 3 is a pair of magnetoelectric conversion elements.
It is necessary to locate the currents at the opposing centers of 1 and 2 and to make the current flow perpendicular to the substrate. Therefore, the conversion element 1,
It is necessary that the through hole of the conducting wire 3 formed on the substrate on which the substrate 2 is formed or mounted is perpendicular to the surface of the substrate and has no play. However, it is extremely difficult to provide such a through hole and dispose the conducting wire in the through hole, and the current detector 8
However, there is a problem that it hinders high performance, and there has been a strong demand for improvement.

[Means for solving problems]

FIG. 1 is a block diagram showing the principle of a current detector according to the present invention.

In FIG. 1, a current detector 11 for the purpose of eliminating the above-mentioned problems comprises a conductor layer 14 which is attached to a hole wall surface of a through hole 13 provided in a predetermined portion of a substrate 12 and through which a current 18 to be measured flows. A magnetic field 19 generated around the conductor layer 14 when a current 18 to be measured flows in the layer 14 is provided with magnetoelectric conversion elements 15 and 16 for performing magnetoelectric conversion in a region facing the periphery of the conductor layer 14. It is characterized by

[Action]

According to the above means, the conductor layer through which the current to be measured flows is formed in the through hole of the substrate, and at least a pair of magnetoelectric conversion elements are provided in the peripheral facing region of the conductor layer, whereby the conductor layer and the magnetoelectric conversion element are provided. The relative positional relationship is fixed with high accuracy. Therefore, the measured value of the measured current is highly accurate and stable, realizing a high-performance current detector.

〔Example〕

A Hall effect element or a magnetoresistive element can be used as the magnetoelectric conversion element used in the present invention. In particular, a detector provided with a barber pole type magnetoresistive element on a substrate is effective in manufacturing and performance.

Hereinafter, the current detector according to the present invention will be described with reference to the drawings.

FIG. 2 is a schematic view showing the main configuration of a current detector according to an embodiment of the present invention, FIG. 3 is a perspective view showing the whole current detection element, and FIG. 4 is a plane showing a barber pole type magnetoresistive element pattern. 5 and 5 are a plan view (a), a bottom view (b), and a side sectional view (c) of the through hole.

In FIG. 2, the magnetoresistive elements 15-1 and 15-2 formed on the surface of the substrate 12-1 made of glass or silicon are shown.
16-1 and 16-2 are examples of paired magnetoresistive elements. A barber pole type is suitable as the magnetic resistance element, and each resistance element 15-1, 15-2, 16-1, 16-2 and the resistance elements 15-3, 16-3 for adjusting their resistance values are , Connected to the bridge as shown.

The through hole 13-1 having a circular cross section formed on the substrate 12-1 is located at the center of each of the resistance elements 15-1, 15-2, 15-3, 16-1, 16-2, 16-3. As shown in FIG. 5, a conductor layer 14 through which a current to be measured flows is deposited on the hole wall, and a land portion 14-1 including external connection terminals is formed integrally with the conductor layer 14 on the surface of the substrate 12-1. Along with the formation, a conductor layer 14-2, which is formed integrally with the conductor layer 14 and serves as an external connection medium, is deposited on the entire back surface of the substrate 12-1. In FIG. 5 (a), the regions sandwiched by the pair of concentric circles indicated by the alternate long and short dash line are resistance elements 15-1, 15-2, 16-
It is a formation region of 1, 16-2.

One diagonal apex of the bridge connecting the resistance elements 15-1 to 16-3 is connected to the constant current source 22, and the other diagonal apex of the bridge is an operational amplifier for differentially combining the outputs of the bridge. Part) 23 is connected.

In the current detector 21 configured as above, the land portion
When the conductors 24 and 25 are connected to the conductor layer 14-1 and the conductor layer 14-2, respectively, and a direct current is applied to the conductor layer 14 through the conductors 24 and 25, the magnetic field generated in the conductor layer 14 becomes the magnetoresistive element 15-1. 15-2,16
-1 and 16-2 are affected in the opposite directions to change their resistance values.

Therefore, the constant current applied from the constant current source 22 to one of the diagonal vertices of the bridge is changed, the output taken from between the other diagonal vertices will be differentially amplified by the operational amplifier 23, If the change in the strength of the magnetic field generated in the conductor layer 14 and the output voltage of the operational amplifier 23 are calibrated in advance, the current value flowing in the conductor layer 14 can be detected from the output voltage of the operational amplifier 23.

When an alternating current flows through the conductor layer 14, a change in the magnetic field strength corresponding to the alternating current peak value can be taken out from between one of the diagonal apexes of the bridge.

FIG. 3 shows a current detection element 26 in which the substrate 12-1 is housed in a package 27, which includes a through hole 13-1, resistance elements 15-1, 15-2, 16
-1, 16-2 and the like formed on the substrate 12-1 is a lead terminal 28-
1 is mounted on an integrally formed metal plate 29, and the land portion 14-1
And lead terminal 28-2, pad 31-1 formed on substrate 12-1
To 4 and lead terminals 28-3 facing the pads 31-1 to 31-4
6 to 6 are connected to each other by a bonding wire 30.

In FIG. 4, barber pole type magnetoresistive elements 15-1, 15-2, 16- formed in a zigzag shape by a known technique.
1, 16-2 are formed by connecting them in a ring shape. However, one end of the magnetoresistive element 15-1 and one end of the magnetoresistive element 16-1 are connected to the bonding pad 31-1 so that the magnetoresistive element 15-1
−1 of the other end of the magnetic resistance element 16-2 is connected to the bonding pad 31-4, and the other end of the magnetic resistance element 16-2 and one end of the magnetic resistance element 15-2 are connected to the bonding pad 31−.
3, the other end of the magnetic resistance element 16-1 is connected to the bonding pad 31-2 via the resistance value adjusting resistance element 16-3, and the other end of the magnetic resistance element 15-2 is adjusted in resistance value. It is connected to the bonding pad 31-2 through the resistance element 15-3 for use.

The zigzag pattern of the resistance elements 15-1, 15-2, 16-1, 16-2 is formed by laminating striped conductive bands on the zigzag magnetic thin film by a lithography technique.

FIG. 6 is a plan view (a) showing a substrate of a current detector according to another embodiment, a bottom view thereof (b), a bottom view thereof (b), a side sectional view of a through hole (c), and FIG. A plan view (a) showing a substrate of a current detector according to still another embodiment, its bottom view (b), AA sectional view (c), and BB sectional view (d).
Is.

As is well known, when a silicon single crystal is etched using a heated alkaline etching solution, it becomes anisotropic etching in which the etching rate varies depending on the crystal orientation. That is, while the etching rate is fast in the (100) and (110) directions on both sides, the etching rate is extremely slow in the (111) plane. Therefore, the (111) plane will remain when etching with an anisotropic etching solution.

Therefore, by using a silicon wafer with an appropriate plane orientation, aligning the through holes of the mask pattern of the oxide film with the appropriate crystal axis direction, and performing anisotropic etching, the silicon substrate has an accurate point symmetric cross section with respect to the center. Through holes are formed.

In FIG. 6, a substrate 12 corresponding to the above-mentioned substrate 12-1.
-2 is a silicon single crystal plate having a plane orientation of (100), and the truncated pyramid-shaped through hole 13-2 is a surface of the silicon substrate 12-2 <
The mask is formed by anisotropic etching with the angle side of the mask aligned with the 110> direction, and the conductor layer 32 through which the current to be measured flows is attached to the hole wall of the through hole 13-2. Two
A land portion 32-1 including external connection terminals is provided on the upper surface of the conductor layer.
32 is formed integrally with the conductor layer 32 and is formed integrally with the conductor layer 32 on the entire lower surface of the substrate 12-2 to serve as an external connection medium.
2 is attached.

An example of the main manufacturing process of the substrate 12-2 will be described below in order of process.

An oxide film by thermal oxidation is formed on the surface of the silicon substrate 12-2 to a thickness of 0.5 to 1.0 μm.

A square through hole is formed in a required portion of the oxide film by photolithography, and a resist mask pattern is completed.
However, one side of the through hole is the surface of the silicon substrate 12-2 <11.
0> direction.

When the through hole 13-2 is opened by anisotropic etching,
The through hole 13-2 has a truncated pyramid shape with an inclination angle of the hole wall and about 55 degrees. However, as an etchant, ethylenediamine 255c
When a mixed solution of 120 g of c, H ₂ O and 45 g of catechol is used at 100 to 110 ° C., the etching depth is 60 to 80 μm / hour, and when the thickness of the silicon substrate 12-2 is 280 μm, the through hole 1
It takes about 4 hours to form 3-2.

An oxide film is formed on the entire surface of the silicon substrate 12-2 by thermal oxidation.

A magnetoresistive element is formed on the surface of the silicon substrate 12-2.

 A protective film for the magnetoresistive element is formed.

 The conductor layers 32, 32-1, 32-2 are deposited.

In FIG. 7, a substrate 12 corresponding to the above-mentioned substrate 12-1.
-3 is a silicon single crystal plate of which both positions are (110), and the upper surface is rhomboid and the lower surface is hexagonal. Through-hole 13-3 has a sharp angle of 70.5 in the surface <111> direction of silicon substrate 12-3. One side of the rhombic through hole of the mask is formed by anisotropic etching, and the obtuse angle portion of the rhombus is etched perpendicularly to the surface, but from the sharp corner of the rhombus to the slope. Is etched. Through hole 13-3
A conductor layer 33 through which a measured current flows is deposited on the hole wall of the
A land portion 33-1 including external connection terminals is formed integrally with the conductor layer 33 on the upper surface of 12-3, and is formed integrally with the conductor layer 33 on the entire lower surface of the substrate 12-3 to serve as an external connection medium. The conductor layer 33-2 is deposited.

The substrate 12-3 is manufactured by the same process as the substrate 12-2.

〔The invention's effect〕

According to the present invention described above, at least a pair of magnetoelectric conversion elements is provided with a through hole at the facing center, and a conductor layer through which a current to be measured flows is formed on the hole wall of the through hole, and the magnetoelectric conversion element and the conductor layer are connected. Since the positional relationship is accurate and fixed, the output change of the magnetoelectric conversion element can be taken out and the measurement current value flowing through the conductor layer can be detected with high accuracy and stability.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of a current detector of the present invention, FIG. 2 is a schematic diagram showing a main configuration of a current detector of one embodiment of the present invention, and FIG. 3 is a perspective view showing an entire current detection element. 4, FIG. 4 is a plan view showing a barber pole type magnetoresistive element pattern, FIG. 5 is a block diagram of a substrate shown in FIG. 2, FIG. 6 is a block diagram of a substrate of a current detector according to another embodiment, 7 is a block diagram of a substrate of a current detector according to still another embodiment, and FIG. 8 is a principle block diagram of a conventional current detector. In the figure, 11,21 are current detectors, 12,12-1,12-2,12-3 are substrates, 1
3,13-1,13-2,13-3 are through holes, 14,32,33 are conductor layers, 1
5, 16 are magnetoelectric conversion elements, 15-1, 15-2, 16-1, 16-2 are barber pole magnetoresistive elements, 17 is a combining part, 18 is a measured current, and 19 is a magnetic loop.

Front page continuation (72) Inventor Noboru Wakatsuki 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (56) References JP-A-63-253264 (JP, A) JP-A-57-128854 (JP) , A)

Claims (8)

[Claims] 1. A through hole (13) provided in a predetermined portion of a substrate (12).
Of the conductor layer (1
4) and a magnetic field (19) generated around the conductor layer (14) when the current to be measured (18) flows through the conductor layer (14) faces the periphery of the conductor layer (14). A current detector comprising a magnetoelectric conversion element (15, 16) for performing a magnetoelectric conversion in a region. 2. The current detector according to claim 1, wherein a magnetoresistive element is used as the magnetoelectric conversion element. 3. The magnetoelectric conversion element (15, 16) is provided on the substrate (1).
The current detector according to claim 1, wherein the current detector is formed in 2). 4. The current detector according to claim 2, wherein the magnetoresistive elements (15, 16) are barber pole type magnetoresistive elements. 5. The current detector according to claim 1, wherein the through hole (13) is formed in the substrate (12) by etching. 6. The method according to claim 5, wherein the substrate (12) is a silicon substrate, and the through hole (13) is formed by utilizing anisotropic etching of silicon.
The current detector according to the item. 7. The surface orientation of the silicon substrate is (110), and the through hole (13) has one opening of a rhombic shape and the other opening of a hexagonal shape, and part of the hole wall is on the surface of the silicon substrate. The current detector according to claim 6, wherein the current detector is formed vertically. 8. The current detector according to claim 6, wherein the silicon substrate has a plane orientation of (100) and the through hole (13) is formed in a square cross section. .