JPS60185129A - Pressure sensor - Google Patents

Abstract

PURPOSE:To improve productivity, by bonding circumference of a flat-plate shaped diaphragm with a bonding agent, fixing a port having a pressure introducing part and a housing by caulking, thereby providing a structure, which is suitable for easy and highly accurate machining and mass productivity. CONSTITUTION:A strain gage 23 is formed on the side of a normal pressure chamber 24 in a flat-plate shape diaphragm 25. An electrode 29 of the gage is connected to a circuit substrate 28 in a housing 21 by a lead wire 30. A port 22 having a pressure introducing part 26 is inserted into the housing 21. O rings 31 and 32 are provided, and the port 22 is fixed by caulking 33. A part between the pressure on the side of the introducing part 26 and the normal pressure side 24 is sealed. A part between the housing 21 and the external pressure is sealed. Since the diaphragm 25 is made flat shape, a structure suitable for easy and highly accurate machining and mass productivity is obtained. A thin film is formed on the flat plate by a sputtering method, and a large amount of strain gages can be manufactured. Therefore the productivity can be improved.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention is based on a method in which a detected pressure J is applied to a flat plate (diaphragm) that can be deformed according to the pressure, and horns of the applied detected pressure are formed on the surface of the diaphragm. This relates to a pressure sensor that converts into an electrical signal using a strain gauge.

This type of pressure sensor is used as a sensor for general industrial hydraulic and pneumatic equipment.

[Prior Art] As a pressure-to-electrical signal conversion means (hereinafter simply referred to as a strain gauge) used in this type of pressure sensor, a resistance strainer is used to convert strain dimensional changes in a resistance wire attached to a diaphragm into an electrical signal. Gauges, semiconductor strain gauges that utilize the piezoresistance effect of a semiconductor crystal attached to a diaphragm, and the like are mainly used.

The strain gauge is used by being attached to a diaphragm that serves as a strain-generating body that generates strain that transmits the detected pressure to the strain gauge. 1 and 2 are plan views showing a conventional example of a pressure sensor in which a strain gauge is attached to a diaphragm.

FIG. 1 shows a boat 2 with a pressure introduction part 6 of a housing 1.
A diaphragm 5 is formed between the housing 1 and the normal pressure chamber 4 by increasing the wall thickness by cutting the housing 1. A strain gauge 3 is attached to the normal pressure chamber 4 side of the diaphragm 5 with adhesive.

Further, FIG. 2 shows a diffusion type semiconductor pressure sensor, which is used as a diaphragm 14 having a substantially concave cross-section, in which a diffusion strain gauge is formed on a silicon single crystal substrate using semiconductor brainer technology. The diaphragm 14 is made of low melting point glass with an adhesive 1.
The base 13 is then die-bonded to the stem 12 with an adhesive 18 such as low melting point glass or resin. And the electrode 15 of the strain gauge
and the boss 16 of the stem 12 are welded together with the gold wire 11,
Configure and cover electrical circuits. Further, the stem 12 and the cylinder 10 whose cylindrical portion is used as a pressure introduction port are sealed by resistance welding or the like to protect semiconductor chips and the like. Note that the atmosphere port 19 is for introducing atmospheric pressure to bring the sub-pressure to atmospheric pressure.

In this type of conventional pressure sensor, the diaphragm is formed by cutting and machining as shown in Figure 1, and although the housing structure is complex, it is necessary to finish it with a high processing power. In particular, the treatment of the diaphragm surface is extremely difficult work, resulting in a lack of productivity and, as a result, the cost has to be increased. In addition, in the diffusion type semiconductor pressure sensor shown in FIG. 2, the wafer is diced into semiconductor chips in individual strain gauge units, and the wafer is sealed in a pedestal 13 using low melting point glass. There is a difference in the coefficient of thermal expansion, and there is a drawback that the thermal response horn changes as the environmental temperature changes at the arrival part. Die bonding also has the same problem of thermal stress as the former, and furthermore, when resin is used as the adhesive, the temperature rise during the bonding process between the electrode 15 and the post 16 causes the bond to deteriorate. There were drawbacks such as deterioration of the agent. The problem of thermal stress results in residual strain and thermal strain. In addition, this type of semiconductor device has drawbacks such as being susceptible to temperature and contamination because the semiconductor of the pressure receiving section comes into contact with the medium to be measured.

Generally, the fixation around the diaphragm of this extreme pressure sensor needs to minimize the occurrence of mechanical and thermal strain. If the fixed part around the diaphragm shifts when it is struck or receives pressure, the diaphragm will not be able to return to its initial state even after the pressure is released.This will affect the strain gauge and appear as hysteresis, especially when using the '10K9/ci scale. In the above-described pressure sensors, it has been considered necessary to securely fix the periphery of the diaphragm in order to ensure stability of performance. In addition, if a low-melting glass or the like is used to fix the area around the diaphragm, the coefficient of thermal expansion will be significantly different from that of the diaphragm.
I had to look at it. In turn, this has become a factor that restricts the productivity of this type of pressure sensor.

1. Purpose of the Invention] The present invention eliminates the above-mentioned drawbacks, makes the shape of the diaphragm easy to process, and has a pressure of about 10 kg/crA or higher [
The purpose is to improve the productivity of operators.

[Structure of the Invention] The present invention includes a flat diaphragm made of an electrical insulator disposed in a housing, and a strain gauge made of an amorphous alloy thin film formed using the flat diaphragm as a substrate, The periphery of the flat diaphragm, which is displaced within the elastic limit due to the pressure received by the diaphragm, is bonded with an epoxy adhesive to improve productivity.

[Embodiments of the invention] FIG. 4 is a cross-sectional view of one embodiment of the present invention.

In the figure, 21 is a housing, and 22 is a boat having a pressure introduction part 26 for guiding the pressure to be detected. The flat diaphragm 25 is interposed between the port 22 and the housing 21, and one surface of the flat diaphragm 25 and the housing 2
The inner wall of 1 forms a normal pressure chamber 24. A strain gauge 23 is formed on the normal pressure chamber 24 side of the flat diaphragm 25, and the electrodes 29 of the strain gauge 23 are connected to the circuit board 28 disposed inside the housing 21 by lead wires 30. There is. The circuit board 28 is further guided to a circuit board 36 equipped with an amplifier circuit, etc., and the lead wire 3 is connected to the circuit board 36 from the circuit board 36.
4 predicts the detection output of the pressure sensor by 1. The circuit board 28 is fixed within the housing with a rubber sealing material 37. Moreover, the space between the housing 21 and the lead wire 34 is sealed by a rubber main 11 knob 35. Then, the blank space formed by the circuit board 28, the inner wall of the housing 21, and the rubber break 35 is filled with epoxy resin 38.

Furthermore, the pressure of the embodiment of the invention shown in FIG.

(a), (b), and (c) of FIG. 3 are manufacturing process diagrams of the pressure sensor of this example.

The diaphragm 25 is formed into a flat plate shape from an electrical insulator such as chemically strengthened glass or partially stabilized reinforced ceramics. The chemically strengthened glass is a glass that is rich in elasticity and pressure resistance, and has the properties of being a good electrical insulator. As a glass having a large size, a Poisson's ratio of 0.22, and an electrically good insulating property, there is a glass commercially available from Corning Co., Ltd. (USA). Further, as the partially stabilized reinforced ceramics, partially stabilized zirconia alleramix can be mentioned.

The diaphragm formed in a flat plate shape is used as a substrate as shown in the manufacturing process diagram (a) in FIG. is processed into a strain gauge pattern (see an example of a strain gauge pattern in FIG. 4). For example, an amorphous alloy thin film (the amorphous alloy used in this example has a composition of N1xSi and B2) is formed on the chemically strengthened glass that forms the flat diaphragm 25 by sputtering, and then photo Apply resist, expose and develop the photoresist using a mask formed according to the strain gauge pattern, bake,
A strain gauge is formed by etching, removing the photoresist, cleaning the surface, etc.

In addition, if an amorphous alloy is used for the strain gauge 23 as in the embodiment of the present invention, the resistance temperature coefficient can be made to a negligible value, and the melt drift can be made extremely small. Further, in the case where an amorphous alloy thin film is formed on the flat diaphragm 25 made of chemically strengthened glass, the linear expansion changes are the same, and it is possible to prevent the occurrence of distortion due to temperature rise between the diaphragms 25 and 25. And the tensile strength can be increased,
A large stress can be applied to the strain gauge, resulting in increased sensitivity. In particular, amorphous alloy thin films formed using the sputtering method can be made thinner than the roll quenching method, so they have higher electrical resistance.
Since the pattern can be made thicker in order to maintain the same resistance value, it is possible to manufacture with a high yield and improve productivity.

Then, as shown in (b) of the manufacturing process diagram in FIG. 3, the flat diaphragm 25 is used as a substrate, and the strain gauge 23 is formed thereon.The lead wire 30 is connected to the electrode 29, and the lead wire 30 is connected to the end of the housing 21. The housing 21 is bonded with an organic adhesive 39 that approximates the line WfJ coating rate. Of course, the ends of the bows 1 to 22 may be bonded with an organic adhesive. According to experiments, the adhesive 39 has a shear tensile strength of 200K.
If the pressure is above g/cM, the diaphragm will not shift up to a pressure twice the measurement range. For example, the shear tensile strength of epoxy adhesives is up to 400 kg/ci, so there is no problem with pressure resistance.

Next, as shown in (C) in the manufacturing process diagram of FIG.
- 22 is inserted, and the boat 22 is fixed with caulking 33. O-rings 31 and 3 are provided between the boat 22 and the flat diaphragm 25 and between the boat 22 and the housing 21.
2, the pressure on the pressure introduction part 26 side and the normal pressure side 2/
11 and the housing 21 is sealed from external pressure.

Then, remove the circuit board 36, fit the rubber seal 37 to the one-digit circuit board 28, insert it into the housing 21, attach the rubber cap 35 to the housing 21, and insert the rubber seal 37 from the hole in the rubber cap 35. The epoxy resin 38 is filled and fixed.

The product manufactured in this manner has a configuration as shown in FIG.

FIG. 6 shows experimental values when the strain gauge pattern shown in FIG. 5 is formed on the flat diaphragm 25 and the pressure P is applied to the pressure introduction part 26, and the relationship between the pressure P and the resistance change rate ΔR/R is shown. It is a characteristic diagram showing a relationship. In the figure, R is the resistance value of the strain gauge, and ΔR is the change in resistance value due to pressure.

As can be seen from the characteristic diagram, even when the periphery of the flat diaphragm 25 is coated with an epoxy adhesive, the distribution applied to the flat diaphragm 25 causes
Distortion in the radial direction and tangential direction of the flat diaphragm 25 occurs. G2 of the strain gauge pattern shown in FIG. G3
The average tensile strain in the tangential direction at the center of the flat diaphragm 25 is detected. This output is as shown in characteristic A. At the same time, distortion occurs in the radial direction of the flat diaphragm 25, and G1 of the J' strain gauge pattern shown in FIG. G4
As shown in characteristic B, the compressive average strain in the radial direction of the peripheral portion can be detected.

Therefore, results similar to those obtained by fixing the periphery of a conventional diaphragm can be obtained.

As described above, according to the embodiment of the present invention, by forming the diaphragm into a flat plate shape, high-precision machining becomes easy and the structure becomes suitable for mass production. Furthermore, since the material of the flat diaphragm is an electrical insulator, a thin film resistor can be formed directly thereon by sputtering, and at the same time a great-circle strain gauge can be manufactured.

Since chemically strengthened glass is used as the flat diaphragm and an amorphous alloy thin film is used as the strain gauge, both have the same linear expansion change and can prevent strain from occurring between them due to temperature TR. In addition, since it is rich in elastic saw and shear stress, it can be used as a pressure sensor for high pressure that can be used under severe temperature conditions.

[Effects of the Invention] As described above, by forming the diaphragm in a flat plate shape, high-precision machining can be performed without interruption, and it is possible to obtain a @ structure suitable for mass production. Since the material is an electrical insulator, when forming a strain gauge on the surface of a flat diaphragm, there is no need to insulate the surface unlike a metallic flat diaphragm. Manufacturing ■ Culms can be made easily. Further, since a thin film can be formed by sputtering using a flat diaphragm as a substrate, a large amount of strain gauges can be manufactured at the same time, and productivity can be improved by being able to manufacture the strain gauges with good continuity.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional pressure sensor with a diaphragm formed by cutting, Fig. 2 is an Ili side view of a conventional pressure sensor with a diaphragm formed with a 2F conductor, and Fig. 3 is a pressure sensor of the wooden embodiment. 4 is a cross-sectional view of the pressure sensor of the present invention, FIG. 5 is a plan view of the strain gauge pattern used in the pressure sensor of the present invention, and FIG. 6 is the strain gauge of FIG. 5. It is a characteristic diagram when a pattern is used for the pressure relief of this invention. In the figure, 21...Housing, 22...Port, 23
... Strain gauge, 24 ... Normal pressure chamber, 25 ... Flat diaphragm, 26 ... Pressure introduction part, 29 ... Electrode, 28 ... Circuit board, 30 and 34 ... Lead line,
31 and 32...O ring, 35...Rubber cap, 39...Adhesive. In addition, in the figures, the same reference numerals and the same symbols indicate the same or equivalent parts. Special 7. r (Applicant: Aisin Seiki Co., Ltd. 1! 11 Patent Attorney Takehisa Higuchi Figure 3, Figure 25, Figure 4, Figure 6, o--1st Year Proceedings Nerti JJE (Spontaneous) December 20, 1980 1, Indication of the case Patent application No. 59-040697 No. 2, name of the invention Pressure sensor 3, relationship with the person making the amendment f1 Patent applicant address 2-1 Asahicho, Kariya City, Aichi Prefecture Name (001)
) Aisin Seiki Co., Ltd. Representative Rei Nakai 4, Agent 500 ffi 0582-62-47
22ζ 岨5 Formula % Formula % Section [3. Detailed Description of the Invention] 7・--1\3,'d
! −' ＼ 6. Contents of correction

[1] The entire text of section [2. Scope of Claims] of the specification is amended as shown in the attached sheet.

[2] In the section [3. Detailed Description of the Invention] of the specification, delete the phrase [especially for pressure sensors of about 10 Kg/cd or more] on page 5, line 6.

[3] In the section [3. Detailed Description of the Invention] of the book, delete the phrase "r' 10 is about 9/ci or more" on page 5, line 16. [4] In the section [3. Detailed Description of the Invention] of the specification, "epoxy-based" from page 6, line 5 to page 6, line 6 will be deleted. 2. Claims (1) A pressure sensor comprising an Ic flat diaphragm arranged in a housing and a strain gauge formed of a thin film resistor using the flat diaphragm as a substrate,
A pressure sensor characterized in that the periphery of the flat diaphragm is adhered with a contact agent, and the boat and the housing having the pressure introduction part on the right side are fixed by caulking. (2) The pressure sensor 1 according to claim 1, wherein the thin film resistor is formed of an amorphous alloy. (3) The pressure lens fogger according to claim 1, wherein the flat diaphragm is made of chemically strengthened glass.

Claims (2)

[Claims] (1) In a pressure sensor consisting of a flat diaphragm made of chemically strengthened glass disposed in a housing and a strain gauge formed of a thin film resistor using the flat diaphragm as a substrate, the periphery of the flat diaphragm is coated with epoxy. A pressure sensor characterized by a structure in which a boat having a pressure introduction part and a housing are fixed together by caulking, as well as being bonded with a type of adhesive. (2) The J King Casenza according to claim 1, wherein the thin film resistor is formed of an amorphous alloy.