WO2019150750A1

WO2019150750A1 - Pressure sensor and production method therefor

Info

Publication number: WO2019150750A1
Application number: PCT/JP2018/044436
Authority: WO
Inventors: 誠古小高
Original assignee: 日本電産コパル電子株式会社
Priority date: 2018-01-30
Filing date: 2018-12-03
Publication date: 2019-08-08

Abstract

A sensor element is provided in a base material 11. A housing 15 provided in the base material has an opening 15a. A diaphragm 16 covers the opening 15a of the housing 15. An insulating fluid 18 is filled inside the housing 15. The diaphragm 16 comprises: a joining section 16a joined to the housing 15; and a main body 16b on the inside of the joining section 16a and being thinner than the thickness of the joining section 16a. Deformation of the diaphragm can be prevented as a result.

Description

Pressure sensor and manufacturing method thereof

Embodiments of the present invention relate to, for example, a pressure sensor that detects the pressure of a gas or a liquid and a manufacturing method thereof.

In the pressure sensor, for example, a housing having a diaphragm is joined to a base material having a sensor chip, and the inside of the housing is filled with an insulating liquid (see, for example, Patent Document 1 and Patent Document 2).

JP-A-10-122997 Japanese Patent No. 3370593

In the above pressure sensor, the diaphragm is fixed to the housing. As the fixing method, for example, welding is used. In general, since the diaphragm is formed of an extremely thin metal material, the diaphragm may be deformed by heat of welding. When the diaphragm is deformed, the sensitivity of the pressure sensor decreases. For this reason, it is desired to prevent the diaphragm from being deformed.

Embodiments of the present invention provide a pressure sensor capable of preventing the deformation of a diaphragm and a manufacturing method thereof.

The pressure sensor according to the present embodiment includes a base material provided with a sensor element, a housing provided in the base material and having an opening, a diaphragm covering the opening of the housing, and an interior of the housing. An insulating liquid, and the diaphragm includes a joint portion joined to the housing, and a main body portion that is thinner than the thickness of the joint portion inside the joint portion.

The pressure sensor manufacturing method according to the present embodiment includes a base material in which a sensor element is disposed, a diaphragm having a joint portion and a main body portion that is thinner than the thickness of the joint portion inside the joint portion, and a housing having an opening portion. The joint portion of the diaphragm is placed on the housing, the opening is covered with the diaphragm, and the joint portion of the diaphragm is welded to the housing.

The embodiment of the present invention can provide a pressure sensor capable of preventing the deformation of the diaphragm and a manufacturing method thereof.

The top view which shows the pressure sensor which concerns on this embodiment. The bottom view which shows the pressure sensor shown in FIG. The disassembled perspective view which shows the pressure sensor shown in FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. 1. Sectional drawing along the VV line of FIG. The circuit diagram which shows an example of the sensor element applied to this embodiment. The flowchart which shows an example of the manufacturing method of this embodiment.

Hereinafter, embodiments will be described with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals.

1 to 5 show a pressure sensor 10 according to the present embodiment.

1 to 3, the pressure sensor 10 includes a base material 11 called a header, a sensor chip 12, a plurality of terminals 13a-13f, an adjustment member 14, a housing 15, a diaphragm 16, and the like.

The sensor chip 12, the plurality of terminals 13a-13f, and the adjustment member 14 are provided on the base material 11, and the housing 15 is attached to the base material 11. The diaphragm 16 is attached to the housing 15.

The base material 11 is made of a metal material, for example, an alloy such as iron, nickel, cobalt, etc., and is plated with gold, for example, in order to increase conductivity. However, the present invention is not limited to this, and the base material 11 can be made of stainless steel or the like.

As shown in FIGS. 3 and 4, the base material 11 includes a circular holding portion 11a having a first diameter D1, and a second diameter D2 that is provided around the holding portion 11a and is larger than the first diameter D1. The first flange 11b having a circular shape is provided.

The base material 11 has a first opening 11c and an injection port 11d penetrating from the front surface to the back surface of the holding portion 11a. The first opening portion 11c is provided in a substantially central portion of the holding portion 11a, and the injection port 11d is provided in the vicinity of the first opening portion 11c.

At the bottom of the base material 11, a pipe 17 communicating with the first opening 11c is provided, and air is introduced to the surface of the holding part 11a through the pipe 17 and the first opening 11c.

The inlet 11d is used to fill the inside of the pressure sensor 10 with an insulating liquid such as silicon oil 18. After filling the silicon oil 18, the injection port 11 d is sealed with a metal ball 19. The sphere 19 is formed of, for example, the same metal material as the base material 11 and is joined to the bottom surface of the base material 11 by welding.

As shown in FIGS. 2 and 5, the base material 11 around the first opening 11c holds a plurality of terminals 13a-13f made of conductive metal. One ends of the terminals 13a-13f are located above the surface of the holding portion 11a.

Between the terminals 13a-13f and the base material 11, for example, glass 20 as an insulating material is filled. The terminals 13a-13f are insulated from the base material 11 by the glass 20, and the gap between the base material 11 and the terminals 13a-13f is sealed by the glass 20.

As shown in FIGS. 3 to 5, a projection 11 e used for projection welding is provided integrally with the first flange 11 b on the surface of the first flange 11 b of the base material 11. The protrusion 11e has a triangular cross section, for example, is spaced from the periphery of the holding portion 11a by a predetermined distance, and is provided over the entire periphery of the first flange 11b.

The protrusion 11e is not necessarily provided on the first flange 11b, and may be provided on a second flange 15b of the housing 15 described later.

As shown in FIGS. 4 and 5, for example, a glass base 21 is provided at the center of the holding portion 11 a. The pedestal 21 is provided with a through hole 21a communicating with the first opening 11c, and the atmosphere is introduced through the through hole 21a.

The sensor chip 12 is provided on the pedestal 21, and the through hole 21 a (first opening 11 c) of the pedestal 21 is sealed with the sensor chip 12. The sensor chip 12 is made of, for example, a silicon substrate, and has a recess 12a on the back surface as shown in FIG. For this reason, the sensor chip 12 has a thin portion corresponding to the recess 12a, and the thin region functions as a diaphragm. On the surface of the sensor chip 12, that is, the surface of the diaphragm, a bridge circuit constituted by a plurality of sensor elements, for example, a Wheatstone bridge circuit is provided.

FIG. 6 shows an example of a Wheatstone bridge circuit applied to this embodiment.

Sensor elements R1, R2, R3, and R4 are, for example, piezoresistors, and are formed on a silicon substrate by, for example, thermal diffusion. The temperature compensation resistors RT1 and RT2 are, for example, thick film resistors formed on the silicon substrate.

The configuration of the bridge circuit is not limited to this, and can be modified.

Further, the sensor elements R1, R2, R3, R4 are not limited to piezoresistors formed by thermal diffusion on the silicon substrate, but, for example, chromium (Cr) and nitrogen (N) formed on the silicon substrate. It may be a thin film resistor containing

As shown in FIGS. 4 and 5, piezoresistors R1, R2, R3, R4 and temperature compensation resistors RT1, RT2 as sensor elements on the sensor chip 12 are connected to terminals 13a-13f by bonding wires 22. .

As shown in FIGS. 3 to 5, an adjustment member 14 is provided on the holding portion 11 a. The adjustment member 14 is formed of an insulator, for example, ceramic. The adjustment member 14 has a function of adjusting the amount of silicon oil 18 accommodated in the pressure sensor 10. For this reason, the adjustment member 14 has an opening 14a shaped to fill the space between the sensor chip 12 and the terminals 13a-13f as much as possible, and has a volume as large as possible inside the pressure sensor 10. Thus, the thickness is determined.

Further, the adjustment member 14 has a function of causing the center of the base material 11 and the center of the housing 15 to coincide with each other, and a function of separating an inner surface of a second opening 15a of the housing 15 described later from the periphery of the holding portion 11a. ing. For this reason, as shown in FIG. 4, the third diameter D3 of the adjustment member 14 is larger than the first diameter D1 of the holding portion 11a and smaller than the second diameter D2 of the first flange 11b.

The adjusting member 14 is attached to the base material 11 using a jig (not shown). For this reason, the center of the adjustment member 14 coincides with the center of the base material 11. The adjustment member 14 is fixed to the holding portion 11a using, for example, an adhesive. The fixing method of the adjustment member 14 is not limited to adhesion.

The housing 15 is substantially cylindrical and has a second opening 15a and a second flange 15b. The housing 15 is formed of, for example, the same metal material as the base material 11, but may be formed of another metal material.

As shown in FIG. 4, the inner diameter of the second opening 15a is substantially equal to the diameter (third diameter) D3 of the adjustment member 14.

The second flange 15 b is provided at one end (lower part) of the cylindrical housing 15 in the longitudinal direction, and is provided in parallel with the first flange 11 b of the base material 11.

In the state where the housing 15 is mounted on the base material 11, the inner surface of the second opening 15 a of the housing 15 contacts the periphery of the adjustment member 14. For this reason, the center of the housing 15 coincides with the centers of the base member 11 and the adjusting member 14, and one end portion in the longitudinal direction of the housing 15 is a distance (D3-D1) / from the periphery of the holding portion 11a of the base member 11. 2 apart.

In the state in which the housing 15 is mounted on the base material 11, the lower surface of the second flange 15 b illustrated is in contact with the tip of the protrusion 11 e provided on the first flange 11 b of the base material 11. In this state, the base material 11 and the housing 15 are joined by, for example, projection welding.

The second opening 15 a of the housing 15 is sealed with a diaphragm 16. The diaphragm 16 is made of, for example, a metal material such as stainless steel.

The diaphragm 16 has a joint portion 16a joined to the other end portion (upper portion) in the longitudinal direction of the housing 15, and has a main body portion 16b inside the joint portion 16a. The main body portion 16b has a concentric bellows structure 16c. However, the bellows structure 16c is not always necessary, and the main body portion 16b may have a flat shape.

The main body 16b is formed by etching a metal material. As shown in the enlarged portion of FIG. 5, the thickness of the metal material, that is, the thickness T1 of the joint portion 16a is, for example, 50 μm, and the thickness T2 of the main body portion 16b is 20 to 30 μm.

Specifically, first, a portion corresponding to the joint 16a of the metal material is masked with a mask material. When the bellows structure 16c is formed, for example, a mask corresponding to the bellows structure 16c is formed in a portion corresponding to the main body portion 16b of a metal material. Thereafter, the main body portion 16b is wet-etched with a chemical solution using these masks.

The formation method of the bellows structure 16c is not limited to this, and the bellows structure 16c can be formed by pressing after the flat main body portion 16b is formed by etching.

The diaphragm 16 formed in this way is joined to the upper surface of the housing 15 around the joint portion 16a by, for example, seam welding using a laser beam. An arrow A shown in the enlarged portion of FIG. 5 indicates a welding position. Thus, the boundary part of the junction part 16a and the housing 15 is welded.

FIG. 7 shows an example of a manufacturing method of the pressure sensor according to the present embodiment.

First, the base material 11, the sensor chip 12, the adjustment member 14, the housing 15, and the diaphragm 16 configured as described above are prepared (S11). The base material 11 may include a plurality of terminals 13a-13f, a pipe 17, a glass 20, and a pedestal 21.

Next, the sensor chip 12 is attached to the base 21 on the holding part 11a, and the first opening part 11c is sealed by the sensor chip 12 (S12).

The sensor chip 12 may be previously arranged on the pedestal 21, or the pedestal 21 on which the sensor chip 12 is arranged may be attached on the holding portion 11a.

Thereafter, the adjusting member 14 is provided on the holding portion 11a (S13). The adjustment member 14 uses a jig (not shown) so that the center of the adjustment member 14 and the center of the base material 11 are aligned, and the periphery of the adjustment member 14 is between the periphery of the holding portion 11a and the periphery of the first flange 11b. Located between. In this state, the sensor elements on the sensor chip 12 are connected to the terminals 13a-13f by the bonding wires 22.

Thereafter, the diaphragm 16 is attached to the housing 15, and the joint portion 16 a of the diaphragm 16 and the housing 15 are welded by, for example, seam welding using laser light, and the entire circumference of the diaphragm 16 is joined to the housing 15. Thereby, the 2nd opening part 15a of the housing 15 is sealed with the diaphragm 16 (S14).

Next, the housing 15 is mounted on the base material 11 by bringing the inner surface of the second opening 15a of the housing 15 into contact with the peripheral surface of the adjustment member 14 (S15). When the housing 15 is mounted on the base material 11, the lower surface of the second flange 15 b illustrated is in contact with the tip of the protrusion 11 e provided on the first flange 11 b of the base material 11.

In this state, when a voltage is applied between the base material 11 and the housing 15, a current flows between the protrusion 11e and the second flange 15b, Joule heat is generated, and the protrusion 11e melts, thereby causing the base material 11 to melt. And the housing 15 are joined (S16). That is, the entire circumference of the base material 11 and the housing 15 is joined.

Next, silicon oil 18 is filled into the inside of the housing 15 from the inlet 11d of the base material 11 (S17), and a metal ball 19 is welded to the inlet 11d, so that the inlet 11d is sealed by the ball 19. It is stopped (S18).

In the above process, after the diaphragm 16 was welded to the housing 15, the housing 15 was welded to the base material 11. However, the present invention is not limited to this, and the diaphragm 16 may be welded to the housing 15 after the housing 15 is welded to the base material 11.

(Effect of embodiment)
According to the embodiment, the adjustment member 14 is provided on the holding portion 11a of the base material 11, and the periphery of the adjustment member 14 is located between the periphery of the holding portion 11a and the periphery of the first flange 11b. When the housing 15 is attached to the base material 11, the inner surface of the second opening 15 a of the metal housing 15 is in contact with the peripheral surface of the insulating adjustment member 14. For this reason, the inner surface of the second opening portion 15a of the housing 15 is separated from the periphery of the metal holding portion 11a by a certain distance and is not in contact with it. Therefore, when a voltage is applied between the housing 15 and the base material 11, current is concentrated between the tip of the protrusion 11e provided on the first flange 11b and the second flange 15b of the housing 15, Since no current flows through this portion, the housing 15 and the base material 11 can be reliably welded at the position of the protrusion 11e. Therefore, the reliability of welding can be improved, and the silicone oil 18 in the housing 15 can be prevented from leaking outside the housing 15.

The joining of the base material 11 and the housing 15 is not limited to projection welding using the protrusions 11e, and for example, seam welding using laser light can be applied. Even when performing seam welding, the base material 11 and the center of the housing 15 coincide with each other, so that the base material 11 and the housing 15 can be reliably joined and liquid leakage can be prevented.

Furthermore, the main body 16b of the diaphragm 16 is formed by etching a metal material. For this reason, the thickness of the diaphragm 16 can be reduced to 20 to 30 μm, and the sensitivity of the pressure sensor can be improved.

Moreover, the diaphragm 16 has a joint portion 16a around the main body portion 16b. The thickness of the joint portion 16a is larger than the thickness of the main body portion 16b, and the joint portion 16a is joined to the housing 15 by welding. Accordingly, the heat generated during welding is almost absorbed by the joint portion 16a having a larger heat capacity than the main body portion 16b, so that the extremely thin main body portion 16b can be prevented from being deformed, and the sensitivity of the pressure sensor 10 is improved. It can be prevented from decreasing.

In the above embodiment, the base material 11, the adjustment member 14, the housing 15, and the diaphragm 16 are not limited to a circle, but may be a rectangle. Even if these shapes are rectangular, it is possible to match the center positions of the base material 11 and the housing 15 by using the adjusting member 14 as in the case of a circular shape.

Further, the outer periphery of the adjusting member 14 and the inner surface of the second opening 15a of the housing 15 may be any shape that can be centered. The outer periphery of the adjusting member 14 and the inner surface of the second opening 15a of the housing 15 may be used. Need not all touch. For example, the outer periphery of the adjustment member 14 and a part of the inner surface of the second opening 15a of the housing 15 may be in contact with each other. In this case, it may be point contact or surface contact. However, since the adjustment member 14 is a member intended to reduce the amount of silicon oil, it is possible to increase the volume when the entire circumference of the adjustment member 14 is in contact with the inner surface of the second opening 15a of the housing 15. Therefore, it is advantageous.

In the above embodiment, the pressure sensor that measures the gauge pressure (differential pressure between the measurement target and the atmospheric pressure) has been described. However, in the case of a pressure sensor that measures absolute pressure, the first opening 11c of the base material 11, the pipe 17, and the through hole 21a of the base 21 can be omitted.

In addition, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The pressure sensor according to the embodiment of the present invention can be applied to detection of gas or liquid pressure.

DESCRIPTION OF SYMBOLS 10 ... Pressure sensor, 11 ... Base material, 11a ... Holding part, 11b ... 1st flange, 11c ... 1st opening part, 11d ... Injection port, 12 ... Sensor chip, 13a-13f ... Terminal, 14 ... Adjustment member , 15 ... housing, 15a ... second opening, 15b ... second flange, 16 ... diaphragm, 16a ... joint, 16b ... main body.

Claims

A base material provided with a sensor element;
A housing provided in the base material and having an opening;
A diaphragm covering the opening of the housing;
An insulating liquid filled in the housing;
Comprising
The diaphragm includes a joint portion joined to the housing, a main body portion thinner than the thickness of the joint portion inside the joint portion,
A pressure sensor comprising:
The pressure sensor according to claim 1, wherein the main body has a thickness of 20 to 30 µm.
Preparing a base material in which a sensor element is arranged, a diaphragm having a joint and a main body thinner than the thickness of the joint at the inside of the joint, and a housing having an opening;
Placing the joint of the diaphragm on the housing, covering the opening with the diaphragm;
Welding the joint of the diaphragm to the housing;
A method for manufacturing a pressure sensor comprising:
After welding the joint of the diaphragm to the housing, the base is provided with the housing,
Filling the inside of the housing with an insulating liquid;
The method of manufacturing a pressure sensor according to claim 3, further comprising:
Before covering the opening with the diaphragm, the base is provided with the housing,
Filling the inside of the housing with an insulating liquid after welding the joint of the diaphragm to the housing;
The method of manufacturing a pressure sensor according to claim 3, further comprising:
6. The method of manufacturing a pressure sensor according to claim 4, wherein the main body of the diaphragm is formed by etching.
6. The method of manufacturing a pressure sensor according to claim 4, wherein the main body of the diaphragm is formed by press working.
The method for manufacturing a pressure sensor according to claim 4, wherein the periphery of the joint portion of the diaphragm is welded to the periphery of the housing.