JPH1090096A - Semiconductor pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and simple semiconductor pressure sensor, which is easily manufactured at low cost, excellent in pressure withstanding strength and operating stably for a long term. SOLUTION: The semiconductor pressure sensor transmits a pressure acting on a diaphragm 5 secured to a header 6, as an absolute pressure, to the pressure detecting part 14 of a pressure detection unit 4 secured onto a stem 12 disposed oppositely to the diaphragm 5 through an encapsulated liquid and obtains a detection output from a lead terminal 11 extending through the stem 12 built in the header 6. The stem 12 is integrated with the lead terminal 11 to produce an integrated member of glass which is then secured directly in the hole of the header 6. Furthermore, a liquid encapsulation passage internally press-fitted with a steel ball 21 having one end opening to the liquid encapsulation chamber and the other end opening to the atmospheric side is provided in same direction as the introducing direction of the lead terminal 11 with respect to the header 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor pressure sensor suitable for use in a high-pressure state, and more particularly, to an improvement in a mounting portion of a pressure sensor at a pressure detecting portion.

[0002]

2. Description of the Related Art In a semiconductor pressure sensor, a piezoresistive layer is provided on the surface of a diaphragm formed of a semiconductor chip such as silicon, and the pressure applied to the diaphragm is converted into an electric signal using a change in the specific resistance of the piezoresistive layer. Air conditioners using compressors, or for home appliances such as refrigerators, for detecting the refrigerant pressure of vehicle air conditioners,
For brake oil pressure detection, medical use,
It is used in a wide range of fields such as industrial measurement.

As shown in FIG. 4, such a semiconductor pressure sensor is provided with a pressure detecting unit 34 in a center space 33 at the tip of a joint 32 having a detection pressure fluid introduction passage 31 in the center. Around a header 36 having a diaphragm 35 fixed so as to cover the void 33,
The semiconductor pressure sensor 30 is formed by connecting with the lid 37. In the central space 33 of the header 36, a cylindrical metal stem 3 having an annular flange 39 at the lower end in FIG.
8, a stem 40 made of ceramic is fitted and fixed. A receiving plate 41 is provided so as to sandwich the flange 39 between lower end surfaces of the stem 40, and an outer peripheral portion 42 that appears to the outside as a joint between the three members is formed. It is fixed liquid-tight by welding.

A through hole 44 is provided in the upper part of the header 36 so that one end communicates with the space 33 and the other end communicates with the outer peripheral surface 43 of the header 36. The ball 45 is press-fitted. Thus, the liquid is sealed in the space 33 in a liquid-tight manner. The inner periphery of the lid 37 to which the joint 32 is fixed is fitted to the outer periphery of the header 36, and the flange 36 at the lower end overlaps the flange of the header 36, and the two are hermetically welded and fixed. Before the lid 37 is fixed and before the steel ball 45 is press-fitted into the through hole 44, the liquid is filled into the space 33 by opening the through hole 44 opened on the outer peripheral surface of the header 36. Supply liquid from the
The steel ball 45 is press-fitted into the through hole 44 as shown in the figure, and then the lid 37 is fixed to the header 36 by welding at its flange portion.

Various types of pressure detecting units in the semiconductor pressure sensor have been conventionally proposed. For example, as shown in FIG. 5, a stem 40 made of ceramic is used.
The opening 48 of the pressure introduction passage 47 formed at the center of
A pressure detecting section 50 having a semiconductor pressure chip fixed on a silicon diaphragm is fixed so that the opening 48 is airtight. A lead wire 51 derived from the semiconductor pressure chip is connected to an end of a lead terminal 52 passing through a terminal insertion hole passing through the stem 40. The inner diameter of the terminal insertion hole is set to be sufficiently larger than the outer shape of the lead terminal 52. After the lead terminal 52 is inserted into the terminal insertion hole, glass powder is put into the gap, heated and melted to form a hermetic seal 53. It constitutes an insulating part.

In addition, as shown in FIG. 6, a pedestal 54 is provided around an opening 48 on the upper end surface of the stem 40.
Are fitted and fixed, and the pressure detecting unit 50 is airtightly fixed thereon similarly to the above. Also in this case, the formation part of the hermetic seal 53 is the same. Further, as shown in FIG. 7, instead of the cage type for detecting a relative pressure with respect to the atmospheric pressure as described above, there is a type for detecting an absolute pressure without providing a pressure introduction passage. In this form, a metal stem 54 is used, the terminal insertion hole is made sufficiently large, a gap with the lead terminal 52 is increased, and a hermetic seal 58 is formed in the gap as described above. The insulation is improved, and the pressure detection unit 50 is fixed on the stem.

Similarly, in a semiconductor pressure sensor of the type which detects an absolute pressure, as shown in FIG. 8, a metal stem 38 is used and a central part is made of Kovar or the like as shown in FIGS. And a material having a thermal expansion coefficient close to that of the pressure detecting section 50 is selected. Further, the terminal insertion hole is made sufficiently large so that a hermetic seal 58 is formed between the lead terminals 52. Some have a pressure detection unit 50 fixed thereto. Furthermore,
FIG. 9 shows a semiconductor pressure sensor that detects absolute pressure.
As shown in FIG. 7, the conventional pressure sensing unit 50 shown in FIG. 7 is provided with a Kovar or glass pedestal 57 on the center upper surface of a stainless steel stem 56, on which the pressure sensing unit 50 is mounted and fixed. Some have done it.

[0008]

In the prior art described above, for example, for detecting the relative pressure with respect to the atmospheric pressure shown in FIGS. 5 and 6, the pressure introducing passage 47 formed in the center of the stem 40 is large. It is necessary to keep it in contact with atmospheric pressure, and there is a disadvantage that workability is poor. 7 to 9
The conventional technique described in (1) requires a large hermetic seal, requires a lot of trouble to form this part, and has the disadvantage of low productivity. In particular, as shown in FIG. 7, the material of the stem must be selected to be close to the coefficient of thermal expansion of the pressure detecting part, which restricts the selection of the material and also requires a device for assembling. Has the disadvantage that it is complicated. In FIG. 8, it is necessary to select a hermetic seal having a coefficient of thermal expansion as close as possible to that of the stem 38. In the case of FIG. Base 5 to be fixed
No. 7 requires a Kovar or glass pedestal, and has a drawback that the manufacturing process is complicated.

Further, as shown in FIG. 4, when the liquid is sealed in the space 33 on the lower surface of the diaphragm 35, one end communicates with the space 33 above the header 36. A through hole 44 is provided so that the other end thereof communicates with the outer peripheral surface 43. After a liquid such as silicon oil is sealed from the through hole 44, a steel ball 45 must be press-fitted. Thereafter, the lid 3 fixing the joint 32
It is necessary to fit the inner circumference of the header 7 to the outer circumference of the header 36 while overlapping the flange of the header 36 with the flange 46 at the lower end, and to fix them together in an airtight manner.

Accordingly, the present invention provides a semiconductor pressure sensor which can be easily manufactured with a small and simple structure, can be an inexpensive semiconductor pressure sensor, and has excellent pressure resistance and stable operation for a long period of time. The purpose is to:

[0011]

According to the present invention, in order to solve the above-mentioned problems, a pressure acting on a diaphragm fixed to a header is fixed on a stem arranged opposite to the diaphragm via a sealed liquid. An absolute pressure type semiconductor pressure sensor configured to transmit a pressure to a pressure detecting unit of a pressure detecting unit and obtain a detection output from a lead terminal extending through a stem provided in the header, and integrating the stem with the lead terminal. One end is open to the liquid filling chamber and the other end is open to the atmosphere in the same direction as the lead terminal introduction direction with respect to the header. And a liquid-filled passage formed by press-fitting a steel ball therein.

Since the present invention is constructed as described above, the fluid pressure acting on the diaphragm is transmitted to the semiconductor pressure sensor of the pressure detecting unit via the sealed liquid sealed on the other side of the diaphragm, and the detection is performed. The output is led out through a lead terminal. In this semiconductor pressure sensor, the pressure detection stem is an integrally formed member of glass in which the lead terminals are integrated, and is directly fixed in the hole of the header, so that it can be easily manufactured with a small and simple structure, and has a pressure resistance. Excellent operation and stable operation for a long time.

[0013]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a semiconductor pressure sensor to which the present invention is applied. The schematic configuration is the same as that shown in FIG. 4 of the related art, and a joint 2 having a detection pressure fluid introduction passage 1 at the center thereof. At the tip, a pressure detection unit 4 is provided in a central space 3, and is connected to a periphery of a header 6 having a diaphragm 5 fixed so as to cover the space 3 by a lid 7 and a semiconductor pressure sensor 8. Is formed.

The details of the pressure detecting unit 4 are shown in FIG. 2, as shown in FIG.
As will be described later in detail, a stem 12 made of a soft glass and hermetically provided with a plurality of lead terminals 11 therein is provided in the center of a flat upper surface 13 of the glass stem 12. First, a pressure detector 14 formed by bonding a silicon wafer, which is a strain gauge, to a semiconductor chip of about 1 mm square is fixed. There is a gap 17 between the substrate 15 of the pressure detecting portion 14 and the flexible portion 16 serving as the pressure detecting portion mounted thereon, and the inside is -1 atm in vacuum. .

The header 6 has a liquid filling passage 20 having one end opening to the lower end surface and the other end opening to a liquid filling chamber 18 formed on the lower surface of the diaphragm 5. After the liquid is filled in the liquid filling chamber, a steel ball 21 for closing this passage is press-fitted into 20.

When the semiconductor pressure sensor 8 shown in FIG. 1 equipped with such a pressure detecting unit 4 is used, a fluid whose pressure is to be measured is introduced from the introduction passage 1, and the diaphragm 5 and the liquid in the liquid sealing chamber 18 are introduced. The pressure detection unit detects the pressure of the introduced fluid via the pressure sensor. This detection pressure indicates an absolute pressure based on the pressure sealed in the gap 17 of the pressure detection portion. The signal is led from the lead terminal 11 to the control device.

At the time of manufacturing the pressure detecting unit 4, as shown in FIG. 3, a cylindrical metal stem 12 is placed in a cylindrical space of a predetermined size formed in a mold 22, and the mold is mounted. The lead terminal 11 is set up in a recess 24 formed on the bottom surface 23 of the base 22 and having an inside diameter into which the lead terminal 11 can be fitted. Next, glass powder of a soft glass such as lead glass is put into the cylindrical metal stem 12 and about 10 mm.
Heat to 00 degrees to melt the glass powder. Thereby, the outer metal stem 12 and the inner lead terminal 11 are all integrated by the molten glass. In this case,
By placing a carbon jig on the surface on which the pressure detector is placed and making contact with the glass surface, the surface can be flattened and the pressure detector can be placed reliably. it can.

After cooling the molten glass, the pressure detecting unit 4 is taken out of the mold 22, and the pressure detecting portion is fixed on the upper surface of the stem with an adhesive or the like as described above. In this way, even when the pressure detecting portion was bonded with the adhesive, no problem occurred in both the pressure characteristics and the temperature characteristics. Next, the end of the lead terminal 11 protruding above the stem and the lead wire 25 of the pressure detection portion are connected by wire using a wire bonder machine. As the lead wire 25, it is preferable to use an aluminum wire having a diameter of about 40 μm.

The semiconductor pressure sensor of the present invention configured as described above is used for detecting a refrigerant pressure of an air conditioner using a compressor, an air conditioner for household appliances such as a refrigerator, and an air conditioner for a vehicle, and for detecting a brake oil pressure. Furthermore, it can be used in a wide range of fields, such as equipment using a steam or hot water boiler, in addition to medical use, industrial measurement, and the like.

[0020]

The present invention is configured as described above.
In this semiconductor pressure sensor, the pressure detecting stem is an integrally formed member of glass in which the lead terminals are integrated and is directly fixed in the hole of the header, so that it can be easily manufactured with a small and simple structure, and has a pressure resistance. Excellent operation and stable operation for a long time. When the liquid is sealed in the manufacture of the semiconductor pressure sensor, one end is opened to the liquid enclosing chamber and the other end is opened to the atmosphere in the same direction as the lead terminal introduction direction with respect to the header. The steel ball that closes the sealing passage during operation of the semiconductor pressure sensor receives only pressure from one direction at all times because the steel ball is sealed from the liquid sealing passage formed by press-fitting the steel ball. Low, excellent pressure resistance and stable operation for a long time. In addition, since the hermetic plate is removed and the insulation distance is increased, the withstand voltage can be improved. Therefore, this semiconductor pressure sensor can be easily manufactured with a small and simple structure, can be an inexpensive semiconductor pressure sensor, and has excellent pressure resistance and stable operation for a long period of time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an overall configuration of a semiconductor pressure sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view of the pressure detection unit.

FIG. 3 is a cross-sectional view of the pressure detecting unit during manufacture.

FIG. 4 is a cross-sectional view showing the entire configuration of a conventional semiconductor pressure sensor.

FIG. 5 is a cross-sectional view of the same pressure detection unit.

FIG. 6 is a sectional view showing another conventional example of the pressure detecting unit.

FIG. 7 is a sectional view showing still another conventional example.

FIG. 8 is a sectional view showing still another conventional example.

FIG. 9 is a sectional view showing still another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Introductory passage 2 Joint 3 Vacuum 4 Pressure detection unit 5 Diaphragm 6 Header 7 Lid 8 Semiconductor pressure sensor 10 Metal stem 11 Lead terminal 12 Stem 13 Upper surface 14 Pressure detector 15 Substrate 16 Flexible portion 17 Void 18 Lower end surface 20 Liquid filling passage 21 steel ball

Claims (4)

[Claims] 1. A pressure acting on a diaphragm fixed to a header is transmitted to a pressure detecting portion of a pressure detecting unit fixed on a stem disposed opposite to the diaphragm via a sealed liquid, and the header is internally mounted. An absolute pressure type semiconductor pressure sensor configured to obtain a detection output from a lead terminal extending through the stem, and the stem is directly formed in a hole of the header by forming the stem into an integrally formed member of glass integrated with the lead terminal. A semiconductor pressure sensor characterized in that: 2. The semiconductor pressure sensor according to claim 1, wherein said stem is made of a melt of soft glass powder. 3. The semiconductor pressure sensor according to claim 1, wherein the stem is provided with a glass powder in a state where a lead wire is provided upright in a hole of the header, and is heated and melted and integrated. 4. The semiconductor pressure sensor according to claim 1, wherein a stem made of a glass melt is provided in a hole of the header via a metal cylindrical stem.