JP-7856369-B2 - Magnetic sensor and method for manufacturing the same

Inventors

• 山地 勇一郎
• 原川 修
• 亀野 誠

Assignees

• ＴＤＫ株式会社

Dates

Publication Date

20260511

Application Date

20200807

Claims (5)

1. circuit board and A sensor chip having an element formation surface on which a magnetic element is formed, mounted on the surface of the substrate such that the element formation surface is perpendicular to the surface of the substrate, The substrate comprises a magnetic collector mounted on the surface such that the first surface faces the element forming surface of the sensor chip, The magnetic collector is a substantially rectangular parallelepiped having a second surface located opposite the first surface, a third surface perpendicular to the first and second surfaces and facing the surface of the substrate, a fourth surface located opposite the third surface, and fifth and sixth surfaces perpendicular to the first to fourth surfaces. The first and second surfaces of the magnetic collector, the third and fourth surfaces of the magnetic collector, and the fifth and sixth surfaces of the magnetic collector have different planar shapes from each other. A magnetic sensor characterized in that the first and second surfaces are planar, thereby the flatness of the first and second surfaces is higher than that of the third and fourth surfaces, and the flatness of the third and fourth surfaces is higher than that of the fifth and sixth surfaces.
2. The magnetic sensor according to claim 1, characterized in that the arithmetic mean waviness Wa of the first and second surfaces is 0.1 μm or less.
3. The magnetic sensor according to claim 1 or 2, characterized in that the magnetic collecting element is made of a ferrite material.
4. The first step is to cut out a roughly rectangular magnetizing body from a block made of magnetic material, A second step involves grinding or polishing the first and second surfaces located on opposite sides of the magnetic collector to flatten the first and second surfaces, A third step is to mount the sensor chip on the surface of the substrate such that the element formation surface on which the magnetic element is formed is perpendicular to the surface of the substrate, The process includes a fourth step of mounting the magnetic collector on the surface of the substrate such that the first surface faces the element forming surface of the sensor chip, and the third surface, which is perpendicular to the first and second surfaces, faces the surface of the substrate. The magnetic collector has a fourth surface located opposite to the third surface, and fifth and sixth surfaces perpendicular to the first to fourth surfaces. The first and second surfaces of the magnetic collector, the third and fourth surfaces of the magnetic collector, and the fifth and sixth surfaces of the magnetic collector have different planar shapes from each other. A method for manufacturing a magnetic sensor, characterized in that, in the second step, the first to fourth surfaces are ground or polished such that the flatness of the first and second surfaces is higher than the flatness of the third and fourth surfaces, and the flatness of the third and fourth surfaces is higher than the flatness of the fifth and sixth surfaces.
5. The fourth step is performed while biasing the magnetic collector so that the first surface of the magnetic collector is pressed against the element forming surface of the sensor chip, as described in claim 4.

Description

This invention relates to a magnetic sensor and a method for manufacturing the same, and more particularly to a magnetic sensor comprising a sensor chip mounted on the surface of a substrate and a magnetic collector, and a method for manufacturing the same. Magnetic sensors are widely used in devices such as ammeters and magnetic encoders. To improve detection sensitivity, magnetic sensors sometimes have a magnetic flux collector attached to the sensor chip. For example, Patent Document 1 discloses a magnetic sensor comprising a sensor chip mounted on a substrate so that the element formation surface is perpendicular to the substrate, and a magnetic flux collector mounted on the substrate so that its end faces the element formation surface. The magnetic sensor described in Patent Document 1 has the advantage of stably holding the magnetic collector on the substrate even when using a long magnetic collector, because the sensor chip is mounted on the substrate at a 90° angle so that the element formation surface is perpendicular to the substrate. Japanese Patent Publication No. 2017-090192 Figure 1 is a schematic perspective view showing the external appearance of a magnetic sensor 10 according to a preferred embodiment of the present invention.Figure 2 is a schematic perspective view illustrating the structure of the element formation surface 20a of the sensor chip 20.Figure 3 is a circuit diagram illustrating the connection relationships between the magnetic elements R1 to R4.Figure 4 is a schematic perspective view illustrating the structure of the magnetic collector 30.Figures 5(a) to 5(c) are schematic diagrams illustrating the application positions of adhesives 71 to 73.Figure 6 is a graph showing the relationship between the arithmetic mean undulation Wa of the surface 31 of the magnetic collector 30 and the gap G that occurs between the element formation surface 20a and the magnetic collector 30.Figure 7 is a graph showing the relationship between the gap G and the sensitivity of the magnetic sensor 10.Figure 8 is a flowchart illustrating the manufacturing process of the magnetic sensor 10.Figure 9 is a schematic diagram illustrating a method for supplying and curing adhesive 71 while biasing the magnetic collector 30. The following describes preferred embodiments of the present invention in detail with reference to the attached drawings. Figure 1 is a schematic perspective view showing the external appearance of a magnetic sensor 10 according to a preferred embodiment of the present invention. As shown in Figure 1, the magnetic sensor 10 according to this embodiment comprises a substrate 2 whose surface constitutes the xz plane, and a sensor chip 20 and magnetic collectors 30, 41, and 42 mounted on the surface of the substrate 2. The sensor chip 20 has an element formation surface 20a that constitutes the xy plane, and one end of the magnetic collector 30 in the z direction faces the element formation surface 20a. The magnetic collectors 41 and 42 are provided on the back side of the sensor chip 20. The magnetic collectors 30, 41, and 42 are blocks made of a soft magnetic material with high magnetic permeability, such as ferrite. As shown in Figure 1, in this embodiment, the sensor chip 20 is mounted such that its element formation surface 20a is perpendicular to the surface of the substrate 2. In other words, the sensor chip 20 is mounted at a 90° angle to the substrate 2. Therefore, even if the length of the magnetic collector 30 in the z-direction is long, the magnetic collector 30 can be stably fixed to the substrate 2. Figure 2 is a schematic perspective view illustrating the structure of the element formation surface 20a of the sensor chip 20. As shown in Figure 2, the sensor chip 20 has a substantially rectangular parallelepiped shape, and four magnetic sensing elements R1 to R4 are formed on the element formation surface 20a that constitutes the xy plane. The magnetic sensing elements R1 to R4 are not particularly limited as long as they are elements whose characteristics change according to the direction or strength of the magnetic field; for example, magnetoresistive elements can be used. In the following description, we will explain using the case where the magnetic sensing elements R1 to R4 are magnetoresistive elements and have the same magnetization fixing direction as an example. Here, the positions of magnetic sensing elements R1 and R3 in the x-direction are the same, and the positions of magnetic sensing elements R2 and R4 in the x-direction are the same. Also, the positions of magnetic sensing elements R1 and R4 in the y-direction are the same, and the positions of magnetic sensing elements R2 and R3 in the y-direction are the same. Magnetic layers 21-23 are formed on the element formation surface 20a of the sensor chip 20. Magnetic layer 21 is located approximately in the center of the element formation surface 20a in a plan view, with magnetic layers 22 and 23 positioned on eithe