Magnetic sensor element

Abstract

The present invention provides a magnetic sensor element that allows for an increase in the number of turns of a detection coil without narrowing the pitch of the detection coil. [Solution] The magnetic sensor element 1 of this disclosure comprises a substrate 3, a magnetic wire 4, and a multilayer coil 2 wound around the magnetic wire 4. The multilayer coil 2 has an inner layer coil 21 wound around the magnetic wire 4 and an outer layer coil 22 wound around the inner layer coil 21. The multilayer coil 2 further has a connection portion 23 that electrically connects the inner layer coil 21 and the outer layer coil 22.

Description

Technical Field

[0001] The present disclosure relates to a magnetic sensor element mounted in a magnetic sensor.

Background Art

[0002] Conventionally, magnetic sensor elements mounted in magnetic sensors are known. For example, Patent Document 1 introduces a magnetic wire provided with a detection coil, in which a lower coil portion and an upper coil portion are bonded and connected together.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Incidentally, in a magnetic sensor element as disclosed in Patent Document 1, sensitivity improves as the number of turns of the detection coil increases. For this reason, in magnetic sensor elements manufactured by MEMS (Micro Electro Mechanical Systems) technology, narrowing the pitch to increase the number of turns of the detection coil has been studied.

[0005] Here, when manufacturing the above-described detection coil, minute displacement occurs when the lower coil portion and the upper coil portion are bonded together. When the pitch is narrowed (the gap between coil wires is reduced), the minute displacement occurring during bonding may degrade the performance of the magnetic sensor.

[0006] Accordingly, an object of the present disclosure is to provide a magnetic sensor element that can increase the number of turns of a detection coil without narrowing the pitch of the detection coil.

Means for Solving the Problem

[0007] To solve the above problems, the magnetic sensor element of this disclosure comprises a substrate, a magnetic wire, and a multilayer coil wound around the magnetic wire, wherein the multilayer coil includes an inner layer coil wound around the magnetic wire and an outer layer coil wound around the inner layer coil. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of the magnetic sensor element of Example 1. [Figure 2] This is a schematic diagram of a multilayer coil in an exploded view. [Figure 3] Figure 1 shows schematic cross-sectional views of the magnetic sensor element, (a) along line AA, (b) along line BB, and (c) along line CC. [Figure 4] This is an explanatory diagram illustrating the manufacturing method of multilayer coils. [Figure 5] (a) A schematic diagram of a modified magnetic sensor element of Example 1, and (b) an exploded schematic diagram of a multilayer coil. [Figure 6] (a) A schematic diagram of the magnetic sensor element of Example 2, and (b) A schematic diagram of the magnetic sensor element of a modified example of Example 2. [Modes for carrying out the invention]

[0009] The magnetic sensor incorporating the magnetic sensor element of this disclosure is a coil-wound magnetic sensor using MEMS technology. Examples of such magnetic sensors include FG (Fluxgate) sensors, MI (Magneto Impedance) sensors, and GSR sensors (registered trademark). In these magnetic sensors, the magnetic sensor element is provided separately from the ASIC (Application Specific Integrated Circuit) (not shown). The magnetic sensor element and the ASIC are joined by wire bonding.

[0010] Hereinafter, two embodiments of this disclosure in a magnetic sensor element, 1 and 2, will be described with reference to the drawings. In Embodiment 2, components similar to those in Embodiment 1 are denoted by the same reference numerals, and their descriptions are omitted. [Examples]

[0011] As shown in Figures 1-3, the magnetic sensor element 1 comprises a substrate 3, a magnetic wire 4 whose characteristics change in response to an external magnetic field, and a multilayer coil 2 wound around the magnetic wire 4.

[0012] The magnetic sensor element 1 includes a wire electrode 5 that supplies electricity to a magnetic wire 4, wiring 7 that electrically connects the magnetic wire 4 and the wire electrode 5, a coil electrode 6 that acquires an electrical signal from a multilayer coil 2, and wiring 7 that electrically connects the multilayer coil 2 and the coil electrode 6.

[0013] The magnetic wire 4 is equipped with wire terminals at both ends. The magnetic wire 4 has a diameter of approximately 5 to 15 μm and is entirely covered with insulating glass approximately 1.0 μm thick. By performing reactive ion etching (RIE method) with carbon tetrafluoroethylene (CF4) gas on both ends of the magnetic wire 4, the insulating glass can be removed and wire terminals can be provided.

[0014] The substrate 3 comprises grooves 31 for arranging magnetic wires 4 and a resin layer 32 that eliminates the step difference between the grooves 31 and the magnetic wires 4. The material of the substrate 3 is, for example, crystal orientation <100> Single-crystal silicon (Si) such as silicon (Si) can be selected. The surface of the substrate 3 is coated with an insulating film of silicon nitride (Si3N4). The resin layer 32 is formed from a positive resist-type resin material.

[0015] The groove 31 is formed in an inverted trapezoidal cross-section, with its inner width narrowing from the groove edge 31a towards the groove bottom 31b. The surface of the groove bottom 31b and the groove bottom corner (the corner between the groove bottom 31b and the groove side surface 31c) is covered with a negative-resist type resin coating. An R-shape is formed on the groove bottom corner and the groove edge 31a to prevent disconnection of the lower coil portions 211 and 221.

[0016] The multilayer coil 2 includes an inner layer coil 21 wound around a magnetic wire 4, and an outer layer coil 22 wound around the inner layer coil 21. The outer layer coil 22 is wound in the same direction as the inner layer coil 21. For example, the outer layer coil 22 may be S-wound and the inner layer coil 21 may be S-wound. Alternatively, the outer layer coil 22 may be Z-wound and the inner layer coil 21 may be Z-wound.

[0017] The multilayer coil 2 includes a connecting portion 23 that connects the inner layer coil 21 and the outer layer coil 22. End portions 2a and 2b of the multilayer coil 2 are connected to coil electrodes 6 via wiring 7. The end portion 2a is provided at an end portion 21a of the inner layer coil 21. The end portion 2b is provided at an end portion 22a of the outer layer coil 22. An end portion 21b of the inner layer coil 21 and an end portion 22b of the outer layer coil 22 are electrically connected at the connecting portion 23 to constitute a single multilayer coil 2.

[0018] The outer layer coil 22 is wound at the same pitch as the inner layer coil 21. The pitch of the inner layer coil and the outer layer coil 22 can be approximately 1.0 to 10.0 μm.

[0019] The inner layer coil 21 includes a plurality of lower coil portions 211 each passing between a substrate 3 and the magnetic wire 4, and a plurality of upper coil portions 212 each connecting adjacent lower coil portions 211 to each other. The lower coil portions 211 and the upper coil portions 212 are bonded to each other at both ends thereof and are electrically connected to each other.

[0020] The outer layer coil 22 includes a plurality of lower coil portions 221 each passing between the substrate 3 and the magnetic wire 4, and a plurality of upper coil portions 222 each connecting adjacent lower coil portions 221 to each other. The lower coil portions 221 and the upper coil portions 222 are bonded to each other at both ends thereof and are electrically connected to each other.

[0021] The lower coil portion 221 of the outer layer coil 22 is a metal wire printed on the substrate 3. The lower coil portion 211 of the inner layer coil 21 is a metal wire printed on the substrate 3 and the outer layer coil 22. The line width of the lower coil portions 211 and 221 is approximately 1.0 to 1.2 µm, and the thickness is approximately 0.7 µm. The line width of the upper coil portions 212 and 222 is approximately 0.5 to 1.5 µm, and the thickness is approximately 0.8 µm.

[0022] A method for forming the multilayer coil 2 having the above configuration will be described with reference to FIG. 4.

[0023] As shown in FIG. 4(a), first, a groove 31 is formed in the substrate 3. As shown in FIG. 4(b), the lower coil portion 221 of the outer layer coil 22 is printed on the substrate 3. As shown in FIG. 4(c), the lower coil portion 211 of the inner layer coil 21 is printed on the substrate 3 and the lower coil portion 221 of the outer layer coil 22. A coil electrode 6 is formed on the substrate 3 at the timing of FIG. 4(b) or FIG. 4(c). At the timing of FIG. 4(c), a connection portion 23 is formed at the confluence position of the end portion 21b of the inner layer coil 21 and the end portion 22b of the outer layer coil 22. Thereafter, as shown in FIG. 4(d), the magnetic wire 4 is placed in the groove 31 on which the lower coil portions 211 and 221 are printed.

[0024] As shown in FIG. 4(e), the upper coil portion 212 of the inner layer coil 21 is bonded to the lower coil portion 211 of the inner layer coil 21. At this time, the end portion 21a of the inner layer coil 21 is connected to the coil electrode 6 via the wiring 7. As shown in FIG. 3(f), the upper coil portion 222 of the outer layer coil 22 is bonded to the lower coil portion 221 of the outer layer coil 22. At this time, the end portion 22a of the outer layer coil 22 is connected to the coil electrode 6 via the wiring 7. Finally, as shown in FIG. 3(g), the end portion 21b of the inner layer coil 21 and the end portion 22b of the outer layer coil 22 are connected to the connection portion 23. Finally, a resin layer 32 is formed to eliminate the step difference between the groove 31 and the magnetic wire 4.

[0025] With the magnetic sensor element 1 configured as described above, since the inner layer coil 21 and the outer layer coil 22 are connected to form a multilayer coil 2, the total number of turns in the multilayer coil 2 can be doubled without narrowing the pitch. Furthermore, because the pitch is not narrowed, misalignment of the bonding between the lower coil sections 211, 221 and the upper coil sections 212, 222 can be suppressed. In other words, with the magnetic sensor element 1 of this disclosure, the performance of the magnetic sensor can be greatly improved by increasing the number of turns in the coil while suppressing the impact on the magnetic sensor by suppressing misalignment of the bonding.

[0026] Furthermore, when using a coil with the same number of turns as a conventional magnetic sensor element (not shown), it is possible to manufacture a smaller magnetic sensor element 1 with a narrower width (width in the longitudinal direction of the coil) than a conventional magnetic sensor element. In this case as well, since the same coil spacing is maintained as in the conventional case, product assurance becomes easier from the standpoint of reliability, such as electromigration.

[0027] As shown in Figure 5, in the modified magnetic sensor element 1 of Example 1, the outer layer coil 22 is wound in the opposite direction to the inner layer coil 21. For example, the outer layer coil 22 can be S-wound and the inner layer coil 21 can be Z-wound. Alternatively, the outer layer coil 22 can be Z-wound and the inner layer coil 21 can be S-wound. Even when using the modified magnetic sensor element 1, the total number of turns in the multilayer coil 2 can be doubled without narrowing the pitch, and a compact magnetic sensor element 1 can be manufactured. [Examples]

[0028] As shown in Figure 6(a), the magnetic sensor element 1 of Embodiment 2 is equipped with an intermediate electrode 6'. By supplying voltage and current from the intermediate electrode 6', the inner layer coil 21 and the outer layer coil 22 form a parallel circuit. The outer layer coil 22 is wound in the same direction as the inner layer coil 21. Because it is a parallel circuit, more precise sensing is possible.

[0029] As shown in Figure 6(b), the modified magnetic sensor element 1 of Embodiment 2 is equipped with an intermediate electrode 6', and the outer layer coil 22 is wound in the opposite direction to the inner layer coil 21. In this modified example, the connection portion 23 is provided near the end 21b of the inner layer coil 21. In the modified example of Embodiment 2, the inner layer coil 21 and the outer layer coil 22 are connected in a parallel circuit by providing the intermediate electrode 6', and the outer layer coil 22 and the inner layer coil 21 are wound in opposite directions. In the modified example of Embodiment 2, the inner layer coil 21 and the outer layer coil 22 are connected in a parallel circuit by providing the intermediate electrode 6', and the outer layer coil 22 and the inner layer coil 21 are wound in opposite directions, so that two response signals of opposite polarity can be obtained from the multilayer coil 2, making it possible to miniaturize the magnetic sensor element 1.

[0030] This disclosure is not limited to the embodiments described above, and it is possible to implement the invention by appropriately changing the shape and configuration of each part without departing from the spirit of this disclosure. For example, although the multilayer coil 2 is shown as having two layers, it is also possible to have three, four, ... n layers. Furthermore, it is also possible to add more intermediate electrodes 6' to have two, three, ... n electrodes. In this case, it becomes possible to measure the magnetic field with greater precision.

Claims

1. The device comprises a substrate, a magnetic wire, and a multilayer coil wound around the magnetic wire, A magnetic sensor element comprising a multilayer coil including an inner layer coil wound around the magnetic wire and an outer layer coil wound around the inner layer coil.

2. The magnetic sensor element according to claim 1, wherein the multilayer coil includes a connection portion in which the inner layer coil and the outer layer coil are electrically connected.

3. The magnetic sensor element according to claim 1 or 2, wherein the outer layer coil is wound in the same direction as the inner layer coil.

4. The magnetic sensor element according to any one of claims 1 to 3, wherein the outer layer coil is wound in the opposite direction to the inner layer coil.

5. The magnetic sensor element according to any one of claims 1 to 4, wherein the outer layer coil is wound at the same pitch as the inner layer coil.

6. The system includes multiple coil electrodes that acquire electrical signals from the multilayer coil, The multilayer coil includes both ends of the multilayer coil and an intermediate portion between the two ends. The coil electrode is connected to both ends and the intermediate portion, respectively, as described in any one of claims 1 to 5.

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