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CN-116075735-B - Magnetic sensor and method for manufacturing the same

CN116075735BCN 116075735 BCN116075735 BCN 116075735BCN-116075735-B

Abstract

The magnetic sensor of the present invention controls the size of a gap generated between an element forming surface and a magnetism collecting body based on the surface properties of the magnetism collecting body so that the deviation between products is within a certain range. The sensor chip (20) is mounted so that the element formation surface (20 a) is perpendicular to the substrate (2), and the magnet collector (30) is mounted so that the surface (31) faces the substrate (2) and the surface (32) faces the element formation surface (20 a). In the magnet assembly (30), the arithmetic average waviness Wa of the surface (32) is 0.1 μm or less. In this way, if the arithmetic average waviness Wa of the surface (32) of the collector (30) facing the element formation surface (20 a) is flattened to 0.1 μm or less, the decrease in detection sensitivity due to the gap between the element formation surface (20 a) and the collector (30) can be greatly reduced, and the variation in detection sensitivity between products can be greatly suppressed.

Inventors

  • YAMAJI ISAMU
  • Yuan Chuanxiu
  • Gui Yecheng

Assignees

  • TDK株式会社

Dates

Publication Date
20260505
Application Date
20210803
Priority Date
20200807

Claims (8)

  1. 1. A magnetic sensor is characterized in that, The device is provided with: A substrate; A sensor chip having an element forming surface on which a magneto-sensitive element is formed and mounted on a surface of the substrate so that the element forming surface is perpendicular to the surface of the substrate, and A magnet collector mounted on the surface of the substrate such that a first surface thereof faces the surface of the substrate and a second surface thereof faces the element formation surface of the sensor chip, The collector body has a third surface on an opposite side of the first surface, The sensor chip and the collector body are fixed to each other via an adhesive applied to the third surfaces of the sensor chip and the collector body, The second surface has a higher planarity than the first surface, The first surface has a higher planarity than the third surface, The arithmetic mean waviness Wa of the second surface is 0.1 μm or less.
  2. 2. A magnetic sensor according to claim 1, wherein, The collector body also has a fourth surface on an opposite side of the second surface, The substrate and the collector body are fixed to each other via an adhesive applied to the surface of the substrate and the fourth surface of the collector body, The first and second surfaces have a flatness that is higher than the flatness of the fourth surface.
  3. 3. A magnetic sensor according to claim 2, wherein, The magnet collector further has fifth and sixth surfaces orthogonal to the first to fourth surfaces and located on opposite sides from each other, The substrate and the collector are fixed to each other via an adhesive applied to the surface of the substrate and the fifth and sixth surfaces of the collector, The first and second surfaces have a flatness that is higher than the flatness of the fifth and sixth surfaces.
  4. 4. A magnetic sensor according to any one of claims 1 to 3, wherein, The collector body is composed of ferrite material.
  5. 5. A method for manufacturing a magnetic sensor is characterized in that, The device is provided with: A first step of cutting out a magnet collector from a block made of a magnetic material; A second step of grinding or polishing the first and second surfaces so that the flatness of the second surface is higher than that of the first surface and so that the flatness of the first surface is higher than that of the third surface, without grinding or polishing a third surface of the magnet collector having the first and second surfaces and a third surface located on the opposite side of the first surface, and setting the arithmetic average waviness Wa of the second surface to 0.1 μm or less; A third step of mounting a sensor chip on the surface of the substrate so that the element formation surface on which the magnetic sensor element is formed is perpendicular to the surface of the substrate, and And a fourth step of mounting the magnet collector on the surface of the substrate so that the first surface faces the surface of the substrate and the second surface faces the element formation surface of the sensor chip, and applying an adhesive to the third surfaces of the sensor chip and the magnet collector.
  6. 6. A method for manufacturing a magnetic sensor according to claim 5, wherein, The fourth step is performed while applying a force to the magnetism collecting body so that the second surface of the magnetism collecting body is pressed against the element forming surface of the sensor chip.
  7. 7. A method for manufacturing a magnetic sensor according to claim 5, wherein, The collector body also has a fourth surface on an opposite side of the second surface, In the second process step, a second step is performed, the fourth surface is not ground or polished and the first and second surfaces are ground or polished, In the fourth step, an adhesive is applied to the surface of the substrate and the fourth surface of the collector body.
  8. 8. A method for manufacturing a magnetic sensor according to claim 7, The magnet collector further has fifth and sixth surfaces orthogonal to the first to fourth surfaces and located on opposite sides from each other, In the second process step, a second step is performed, the first and second surfaces are ground or polished without grinding or polishing the fifth and sixth surfaces, In the fourth step, an adhesive is applied to the surface of the substrate and the fifth and sixth surfaces of the magnet assembly.

Description

Magnetic sensor and method for manufacturing the same Technical Field The present invention relates to a magnetic sensor and a method for manufacturing the same, and more particularly, to a magnetic sensor including a sensor chip and a magnetism collecting body mounted on a surface of a substrate, and a method for manufacturing the same. Background Magnetic sensors are widely used in ammeters, magnetic encoders, and the like. In order to improve the detection sensitivity, a magnetic sensor may be provided with a magnet assembly for focusing magnetic flux on a sensor chip. For example, patent document 1 discloses a magnetic sensor including a sensor chip mounted on a substrate so that an element formation surface is perpendicular to the substrate, and a magnet collector mounted on the substrate so that an end portion thereof faces the element formation surface. The magnetic sensor described in patent document 1 has an advantage in that the sensor chip is placed on the substrate by 90 ° so that the element formation surface is perpendicular to the substrate, and therefore, even when a long magnet collector is used, the magnet collector can be stably held on the substrate. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2017-090192 Disclosure of Invention Problems to be solved by the invention However, when the processing accuracy of the magnet assembly is low, the element formation surface of the sensor chip and the magnet assembly cannot be completely adhered to each other, and a minute gap may be generated therebetween. Since this gap has a large influence on the detection sensitivity of the magnetic field, it is desirable to control the size of the gap so that the deviation between products falls within a certain range. Here, in order to reduce the gap between the element formation surface of the sensor chip and the magnet collector as small as possible and to control the gap size so that the variation between products falls within a certain range, there is a method of grinding or polishing the surface of the magnet collector to improve the flatness of each surface and to make the angle formed by the two surfaces closer to 90 °. However, at present, the relationship between the surface properties of the magnet collectors and the gaps generated between the element formation surfaces and the magnet collectors is unknown, and therefore, it is difficult to suppress the variation between products. Accordingly, an object of the present invention is to provide a magnetic sensor and a method for manufacturing the same, which can control the size of a gap generated between an element forming surface and a magnetism collecting body based on the surface properties of the magnetism collecting body so as to reduce the variation between products within a certain range. Technical scheme for solving problems A magnetic sensor is provided with a substrate, a sensor chip having an element formation surface on which a magneto-sensitive element is formed, the sensor chip being mounted on the surface of the substrate so that the element formation surface is perpendicular to the surface of the substrate, and a magnet collector mounted on the surface of the substrate so that a first surface faces the surface of the substrate and a second surface faces the element formation surface of the sensor chip, wherein the arithmetic average waviness Wa of the second surface is 0.1 [ mu ] m or less. According to the present invention, since the arithmetic average waviness Wa of the second surface of the collector body opposed to the element formation surface is flattened to 0.1 μm or less, the decrease in detection sensitivity caused by the gap between the element formation surface and the collector body can be greatly reduced, and the variation in detection sensitivity between products can be greatly suppressed. In the present invention, the first and second surfaces may have a higher flatness than at least one other surface in the magnet assembly. Accordingly, since the flatness of at least one other surface of the magnet collector is not improved, unnecessary manufacturing costs for processing the surface are not generated. This can suppress an increase in manufacturing cost. In the present invention, the magnet collecting body may have a third surface, the sensor chip and the magnet collecting body may be fixed to each other via an adhesive applied to the third surface of the sensor chip and the magnet collecting body, and the first and second surfaces may have a flatness higher than that of the third surface. Accordingly, unnecessary manufacturing costs for processing the third surface are not generated. Further, the third surface has low flatness, so that the adhesive strength of the adhesive can be sufficiently ensured. In the present invention, the magnet collector may further have a fourth surface, and the substrate and the magnet collector may be fixed to each other via an adhesi