JPH06288852A - Pressure sensor - Google Patents

Abstract

PURPOSE:To provide a pressure sensor which has a simple construction and can be easily produced. CONSTITUTION:A capacitive pressure conversion element 10 is provided with a substrate 11 with a thick wall and an elastic diaphragm 12 with a thin wall which is arranged to face the substrate 11 at a specified interval, and electrode holes 45 to 47 penetrating the substrate 11 are made to take out electrodes 31 to 33 on the substrate 11 side to the rear surface of the substrate 11, and by the through-holes formed in the central parts of the holes 45 to 47, the passage can be ensured to lead into a space 30 a fluid such as an air, etc., that becomes a reference pressure for pressure measurement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor for detecting the pressure of a fluid to be measured, and more particularly to a capacitance type pressure sensor for detecting the pressure by utilizing a change in capacitance between opposed electrodes. Regarding

[0002]

2. Description of the Related Art FIG. 12 shows a pressure conversion element 900 which is an example of a capacitance type pressure sensor (Japanese Patent Laid-Open No. Sho 60).
-56233 gazette). The pressure conversion element 900 is a thick substrate
901 and a thin-walled diaphragm 902 that is deformed by the pressure of the measured fluid.
2 are arranged in parallel to each other with a predetermined gap therebetween via a ring-shaped joint portion 903. Board 901 and diaphragm
A space 906 is formed between the facing surfaces 904 and 905 facing the 902 so as to be surrounded by the joint portion 903. Opposite side 90 of board 901
The electrode 4 is provided with two electrodes 910 and 911, while the electrode 912 is provided on the facing surface 905 of the diaphragm 902. The electrodes 910 and 912 form a capacitor 914, and the electrodes 911 and 912 form a capacitor 915. Each of these electrodes 910, 911, 912 is provided with a projecting portion toward the outer end at one location of each outer edge, and these projecting portions are further provided with lead wires 916, 917, 918, respectively.
Are connected, and the electrodes 910, 911, 912 are taken out to the outside by these. The substrate 901 is provided with a through hole 919 that communicates the space 906 with the outside, and the atmosphere serving as the reference pressure is supplied from the through hole 919 to the space 906.
It is designed to be guided inside. Also, the diaphragm 90
The surface opposite to the second facing surface 905 is a pressure receiving surface 907 to which the pressure of the measurement fluid is applied. In such a pressure conversion element 900, the atmosphere is introduced into the space 906 to be the reference pressure, while the pressure of the measurement fluid is applied from the pressure receiving surface 907.
The diaphragm 902 is deflected by these pressure differences. As the diaphragm 902 flexes, the electrodes 910, 912
The pressure of the fluid to be measured is detected by utilizing the fact that the distance between them and the distance between the electrodes 911 and 912 change, and the capacitance of each capacitor 914 and 915 changes.

Further, in such a capacitance type pressure conversion element, the electrode can be taken out from the outside by the lead wires 916, 917, 918 at the outer end of the pressure conversion element 900 as in the conventional example shown in FIG. In addition, there is also an example in which a through hole is provided in the substrate, a conductive portion is formed in this through hole, and the electrode is taken out on the back side of the substrate (the side opposite to the electrode installation surface) (Japanese Examined Patent Publication No. 63-9174). See Japanese Utility Model Laid-Open No. 57-105943, etc.).

[0004]

However, in the conventional example of FIG. 12 described above, in order to take out the electrodes 910, 911, 912 to the outside, a protruding portion toward the outer end is provided at one location of the outer edges of the electrodes 910, 911, 912. , To each lead wire 916,917,
In addition to having to connect the 918, the passage for introducing the atmosphere, which is the reference pressure for pressure measurement, into the space 906 is a through hole 919 that is provided separately from the structure for taking out these electrodes 910, 911, 912 to the outside. Therefore, there is a problem that the manufacturing process is complicated and the manufacturing cost cannot be reduced. Further, even when the electrode is taken out by providing the through hole in the above-mentioned substrate, since the through hole is provided only for taking out the electrode, it is necessary to secure a passage for introducing the atmosphere into the space. However, a hole different from the through hole must be provided, and the manufacturing process becomes complicated as in the case of the conventional example of FIG. 12, and there is a problem that the manufacturing cost cannot be reduced.

An object of the present invention is to provide a pressure sensor which has a simple structure and can be manufactured easily and surely.

[0006]

SUMMARY OF THE INVENTION The present invention utilizes a through hole formed in the central portion of an electrode hole for taking out an electrode to measure a pressure in a space formed between a substrate and an elastic diaphragm. It is intended to achieve the above-mentioned object by introducing a fluid such as the atmosphere, which serves as a reference pressure. Specifically, the present invention includes a thick-walled substrate and a thin-walled elastic diaphragm that is opposed to the substrate at a predetermined interval, and faces each of the facing surfaces of the substrate and the elastic diaphragm. An electrode is provided, which is a pressure sensor for detecting a pressure applied to the elastic diaphragm by a change in electrostatic capacitance between the electrodes, wherein an electrode terminal for an electrode on the substrate side of the electrodes is an electrode installation surface of the substrate. Is formed on the inner wall surface of the electrode hole provided so as to penetrate the substrate, the conducting portion being provided on the opposite surface and conducting the electrode on the substrate side and the electrode terminal for this electrode. A through hole is formed in the central portion of the electrode hole so as to be surrounded by, and the through hole is filled with a fluid such as air serving as a reference pressure for pressure measurement in a space formed between the substrate and the elastic diaphragm. Lead Characterized in that it is a road.

Here, in the conductive portion, the material of the electrode on the substrate side and the material of the electrode terminal for this electrode are the same, and the electrode on the substrate side and the electrode terminal for this electrode are formed respectively. At this time, it is preferable that the material on each side is vacuum-sucked from the opposite side of the electrode hole so as to propagate along the inner wall surface of the electrode hole, and the materials on both sides are conducted inside the electrode hole. Further, it is desirable that the material is silver palladium paste.

[0008]

In the present invention as described above, the fluid such as the atmosphere serving as the reference pressure for pressure measurement is introduced into the space formed between the substrate and the elastic diaphragm, while the pressure of the measured fluid acts on the elastic diaphragm. Then, it is bent, and the pressure of the measurement fluid is detected by catching the change in the capacitance with the change in the distance between the opposing electrodes at this time. At this time, a fluid such as the atmosphere is introduced into the space through a through hole formed in the central portion of the electrode hole for taking out the electrode from the outside. For this reason, the structure of the pressure sensor becomes simpler than in the case where a passage for guiding a fluid such as the atmosphere into the space is provided in a separate process, the manufacturing process is reduced, and the manufacturing cost is reduced. Further, when forming a through hole as a passage for introducing a fluid such as the atmosphere into such a space in the central portion of the electrode hole for taking out the electrode to the outside, the electrodes corresponding to the inlet portions on both sides of the electrode hole and By making the material of the electrode terminals the same and vacuum suctioning the material on each side from the opposite side of the electrode hole to form the conducting part,
A passage for guiding the fluid such as the atmosphere into the space is easily secured, and so-called erosion phenomenon (a phenomenon in which one material diffuses into the other material and disappears) also occurs when the electrode is taken out. As a result, more reliable conduction is achieved as compared with the case of conduction between different kinds of materials which may cause conduction failure, thereby achieving the above object.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 show a capacitance type pressure conversion element 10 according to a first embodiment of the present invention. In FIG. 1, the pressure conversion element 10 is mounted inside a pressure sensor (not shown), and converts the pressure of the measurement fluid into an electric output signal in order to detect the pressure. The pressure conversion element 10 has a flat columnar main body 10A, which includes a thick ceramic substrate 11 and a thin diaphragm 12 made of ceramic that is deformed by the pressure of a measured fluid. The substrate 11 and the diaphragm 12 are arranged in parallel with each other with a predetermined gap therebetween via the joint portion 20. A space 30 is formed between the facing surfaces 13 and 14 of the substrate 11 and the diaphragm 12 so as to be surrounded by the ring-shaped joint portion 20.

As shown in FIG. 2, on the facing surface 13 of the substrate 11, a solid circular central electrode 31, whose central portion is not removed,
Each ring-shaped reference electrode 32 and shield electrode 33
Are provided in total, while a solid circular common electrode 34 is provided on the facing surface 14 of the diaphragm 12. FIG. 2 is a view of the substrate 11 and the diaphragm 12 as seen from the facing surfaces 13 and 14 respectively (the joining portion 20 is not formed). Note that the hatching in the drawing is not a cross section, but is shown for the sake of clarity in explanation, and the hatching in FIGS. 3A and 9 described later is also the same. On the facing surface 13 of the substrate 11,
The central electrode 31 is formed into a solid circular shape and serves as a reference electrode.
32 is a circular ring (ring shape) closed so as to surround the central electrode 31.
The shield electrode 33 is formed in a closed annular shape (ring shape) so as to surround the reference electrode 32. The distance S1 between the central electrode 31 and the reference electrode 32 and the distance S2 between the reference electrode 32 and the shield electrode 33 are each about 500 μm, for example. On the facing surface 14 of the diaphragm 12, the common electrode 34
Is formed into a solid circular shape, and its outer diameter DC is the shield electrode
A portion of the common electrode 34, which is larger than the outer diameter DS and is located outside the outer edge of the shield electrode 33, serves as an outer edge portion 38 for forming an electrode terminal described later. Also,
On the outside of the shield electrode 33 on the facing surface 13 of the substrate 11, a connection terminal 39 that is electrically connected to the outer edge portion 38 of the common electrode 34 is formed of a conductive material such as silver palladium paste.

Returning to FIG. 1, a space is formed by each of these electrodes.
A total of three capacitors with the atmosphere in 30 as the dielectric are formed. That is, the central electrode 31 and the common electrode 34 form a capacitor 35 having a capacitance CM and a reference electrode 32.
The common electrode 34 and the common electrode 34 form a capacitor 36 having a capacitance CR, and the shield electrode 33 and the common electrode 34 form a capacitor 37 having a capacitance CS. The inter-electrode distance T of each of the capacitors 35, 36, 37 is determined by the thickness of the joint portion 20, and in the state where no pressure acts on the diaphragm 12,
For example, it is about 50 μm. The surface of the diaphragm 12 opposite to the facing surface 14 is a pressure receiving surface 16 to which the pressure of the measurement fluid is applied. The pressure conversion element 10 has a space 30 and the pressure of the measurement fluid acting on the pressure receiving surface 16 of the diaphragm 12.
The diaphragm 12 bends due to the pressure difference from the atmospheric pressure inside, and the inter-electrode distance of each capacitor 35, 36, 37 changes from its initial value T, and each capacitance CM, CR, CS changes accordingly. This is utilized to detect the pressure of the measurement fluid.

A one-chip IC 60 is mounted on the back surface 15 (the surface opposite to the facing surface 13) of the substrate 11. This one-chip IC 60 is a C-MOS, as will be described later in detail.
ASIC (custom IC) with each capacitance CM, C
Measuring circuit 65 for measuring changes in R and CS (see Fig. 5 below)
Built in. Further, an electrode pattern 40 for directly mounting the one-chip IC 60 is formed on the back surface 15 of the substrate 11 by printing. FIG. 3 shows a detailed configuration of the electrode pattern 40. (A) shows a state before the one-chip IC 60 is mounted, and (B) shows a state after the one-chip IC 60 is mounted. . The electrode pattern 40 includes a circuit path 63A formed in a ring shape on the outer edge of the back surface 15 of the substrate 11, and an electrode for the shield electrode 33 on the substrate 11 side is formed on the inner protruding portion on the right side of the circuit path 63A in the figure. The terminal 43 is formed in an electrically conductive state. On the other hand, inside the circuit path 63A, the central electrode 31 on the substrate 11 side, the respective electrode terminals 41 and 42 for the reference electrode 32, and the common electrode 34 on the diaphragm 12 side.
Electrode terminals 44 are formed in spots, and key-shaped circuit paths 61, 62, and 64 are formed from these electrode terminals 41, 42, and 44, respectively, and the tips thereof are formed by the one-chip IC 60.
Is guided to the position of the foot (pin). At this time, the common electrode
Around the electrode terminal 44 for 34 and the circuit path 64, a circuit path 63B is provided at a predetermined interval.
Is connected to the inside of the left side portion of the ring-shaped circuit path 63A in the figure and is integrated with the circuit path 63A. Further, the circuit path 63B is arranged so as to pass through the foot positions of the one-chip IC 60 located on both sides of the tip of the circuit path 64, and is connected to the grounding terminal of the one-chip IC 60. The circuit paths 63A and 63B electrically connected to the electrode terminals 43 for the shield electrode 33 are grounded. Therefore, the circuit path 61 including the electrode terminal 41 for the central electrode 31 and the circuit path 62 including the electrode terminal 42 for the reference electrode 32.
And the circuit path 64 including the electrode terminal 44 for the common electrode 34,
The circuit paths 63A and 63B as ground electrodes are arranged so as to be isolated from each other. Therefore, it is possible to reduce the influence of an increase in leak current due to a decrease in insulation resistance between them.

As shown in FIG. 1, the electrode terminals 41, 42, 43, 44 have conductive portions 51, 46 formed in electrode holes 45, 46, 47, 48 provided so as to penetrate the substrate 11, respectively. 52, 53, 54
Thus, the central electrode 31, the reference electrode 32, the shield electrode 33, and the common electrode 34 are electrically connected to the connecting terminal 39, respectively. At this time, the conducting parts 51, 52, 53, 54
Are provided on the inner wall surfaces of the electrode holes 45, 46, 47, 48, respectively, and a through hole is formed at the center of each hole. Of these, the through holes of the electrode holes 48 are closed by the conductive paste 25 described later, but the remaining electrode holes 45, 46,
At least one of the through holes of 47 is open on both sides so that outside air can be introduced into the space 30.

FIG. 4 shows a detailed cross section of the joint portion 20. The bonding portion 20 is an overcoat glass 21 closely attached to the substrate 11 side so as to cover the outer peripheral side of the shield electrode 33.
A ring-shaped high melting point glass 22 provided between them to adjust the distance between the overcoat glass 21 and the diaphragm 12, and between the overcoat glass 21 and the diaphragm 12. The high melting point glass 22 and the low melting point glass 23 arranged around the inner peripheral side and the outer peripheral side thereof are included. The overcoat glass 21 is provided to increase the edge distance between the shield electrode 33 and the common electrode 34 and increase the edge resistance.
The high-melting-point glass 22 is a crystallized glass or the like, and its thickness is adjusted so that the distance between the substrate 11 and the diaphragm 12, that is, the inter-electrode distance T is maintained at a predetermined distance. Diaphragm 12 is commonly used to change the pressure range.
The thickness of the high melting point glass 22 may be adjusted to change the distance T between the electrodes. The low-melting glass 23 is an amorphous glass or the like, and a space 24 is provided in a part thereof. In this space 24, a conductive paste 25 that electrically connects the outer edge portion 38 of the common electrode 34 and the connection terminal 39 is inserted, and the space 24 prevents the protrusion when the conductive paste 25 is inserted in a manufacturing process described later. Is separated from the space 30 by the low melting point glass 23. As a result, the common electrode 34 has its outer edge 38
From the above, the conductive paste 25, the connecting terminal 39, and the conducting portion 54 are conducted in this order to the electrode terminals 44 on the back surface 15 of the substrate 11. Further, a part of the space 24 into which the conductive paste 25 is inserted is also formed at the corresponding position of the overcoat glass 21.
It should be noted that such a space 24 may be provided in the high melting point glass 22 depending on the arrangement of the high melting point glass 22.

FIG. 5 shows a measuring circuit 65 built in the one-chip IC 60. In FIG. 5, the measurement circuit 65
Is a circuit means for obtaining an output signal related to the ratio of the sum of the capacitances CM and CR of the capacitors 35 and 36 in the body 10A of the pressure conversion element 10 and the difference thereof, as will be described later in detail. In addition to this, the zero point adjusting circuit 71 which is a zero point adjusting means for adjusting the zero point of the output signal of the measuring circuit 65, the pressure of the measurement fluid input and added to the diaphragm 12 of the main body 10A, and the pressure to be obtained for this In relation to the output signal of the measuring circuit 65, a span adjusting circuit 72 which is a span adjusting means for adjusting the magnitude relationship (span) between the range of the pressure on the input side and the range of the output signal on the output side, and the pressure applied to the input And a linearity correction circuit 73 which is a linearity correction means for correcting the linearity of the relationship between the output signal and the output signal.

The circuit 70 includes an operational amplifier 83, and the output signals of the span adjusting circuit 72 and the linearity correcting circuit 73 are input to the negative terminal of the operational amplifier 83. The output side of the operational amplifier 83 is directly connected to one terminal of the switch 75 and also connected to one terminal of the switch 74 via the operational amplifier 84. Each of these switches
The common terminals of 75 and 74 are connected to the central electrode 31 and the reference electrode 32, which are one of the electrodes of the capacitors 35 and 36, respectively. The common electrode 34, which is the other electrode of each capacitor 35, 36, is connected to the negative terminal of the operational amplifier 85 via the switch 76, and the output side of the operational amplifier 85 is common to the other terminal of each switch 75, 74. In addition to being connected, it is connected to the negative terminal of the operational amplifier 86. Further, a capacitor 77 for data hold (details will be described later) is provided between the output side of the operational amplifier 85 and the negative terminal.
(Capacitance C0) is provided. The output signal of the zero adjustment circuit 71 is input to the negative terminal of the operational amplifier 86, and the output side of the operational amplifier 86 is connected to the output terminal 78 and output to the linearity correction circuit 73. It is designed to feed back a signal. In addition,
The positive terminals of the operational amplifiers 83 to 86 are grounded.

The zero-point adjusting circuit 71, the span adjusting circuit 72, and the linearity correcting circuit 73 are each composed of a plurality of zeners connected in parallel to the digital-analog converter 80 (DAC).
By having a zap diode 81 (indicated by n in FIG. 5) and trimming these by the required number of bits,
The output signal can be adjusted according to each function.

In FIG. 5, circuit 70 includes three switches.
74, 75, 76 are provided, and these are adapted to switch between the dotted line and the solid line in the figure. First, each switch 74, 7
When 5, 76 are in dotted line, each capacitor 3 in the main unit 10A
The output voltage VI of the operational amplifier 83 and the output voltage −VI of the operational amplifier 84 are applied to 5 and 36, and the charges QM and QR corresponding to the respective capacitances CM and CR are QM = −CM × VI, QR = CR × Stored by VI. Here, to give concrete examples of the voltage, the capacitance, etc., the voltage VI is about 2.5V (2 × VI = 5V), and each capacitance CM,
CR is, for example, 30 pF, and the capacitance CM of the capacitor 35 normally changes by about 6 to 8 pF due to the deflection of the diaphragm 12.
On the other hand, the capacitance CR of the capacitor 36 changes by 1 to 2 pF,
The difference between both capacitances is about 5 to 6 pF. Next, when the switches 74, 75 and 76 are in the solid line state, the difference ΔQ between the charges QM and QR stored in the capacitors 35 and 36 moves to the capacitor 77 having the electrostatic capacitance C0. At this time, if QR> QM, the voltages VX of the capacitors 35 and 36 are balanced in the state of the following equation. VX = (QR−ΔQ) / CR = (QM + ΔQ) / CM From this, ΔQ = (CM × QR−CR × QM) / (CR + CM) is obtained. Therefore, due to the movement of this charge ΔQ, the operational amplifier is
The output voltage VO of 85 is VO = VX = (QR−ΔQ) / CR = [CR × VI − {(CM × QR−CR × QM) / (CR + CM)}] / CR = [CR × VI − {( CM × CR × VI + CR × CM × VI) / (CR + CM)}] / CR = {(CR-CM) / (CR + CM)} × VI, which is the sum of the capacitances CM and CR of the capacitors 35 and 36. It is now possible to obtain an output signal related to the ratio to.

In the first embodiment, the pressure of the measuring fluid is detected as follows. First, the pressure of the measurement fluid is applied to the pressure receiving surface 16 of the diaphragm 12, and at the same time, the atmosphere is introduced into the space 30 through at least one of the through holes formed in the electrode holes 45, 46, 47. The inside is atmospheric pressure. At this time, the diaphragm 12 is bent by the pressure difference between the pressure receiving surface 16 side and the space 30 side. Usually space
Although it bends to the 30 side, it bends to the opposite side when the pressure of the measured fluid is negative (below atmospheric pressure). Next, the measurement circuit 65 captures the change in each capacitance CM, CR due to the change in the electrode distance of each capacitor 35, 36 due to the deflection of the diaphragm 12, and the capacitance CM, CR of each capacitor 35, 36 is captured. Obtain an output signal related to the ratio of the sum and the difference of. Then, by calibrating the relationship between the output signal and the pressure in advance, the pressure of the measurement fluid corresponding to the detected output signal is obtained.

Hereinafter, the pressure conversion element 10 according to the first embodiment will be described.
An example of the manufacturing method will be described. First, in the manufacturing step (1), the substrate 11 and the diaphragm 12 are processed and formed by using an appropriate material, for example, alumina ceramics. Alumina (Al ₂ O ₃ ) is a typical fine ceramics material, has a high melting point, is hard, and is excellent in electrical insulation. Board 11
The thickness of the diaphragm 12 is usually about 4 mm, and the thickness of the diaphragm 12 is usually 0.2 mm to 1.0 mm, although it varies depending on the pressure range of the pressure to be measured and the relationship with the effective diameter of the diaphragm 12.
It is a degree.

Next, in the manufacturing process (2), each electrode and the joint portion 20 are printed and fired on the substrate 11 and the diaphragm 12. This printing and firing can all be performed using hybrid IC (HIC) manufacturing techniques and machines. In the manufacturing process (2A), the central electrode 3 is arranged on the front surface (opposing surface 13) of the substrate 11 as shown in FIG.
1, three electrodes of the reference electrode 32, the shield electrode 33, and the connection terminal 39 are screen-printed. The printing material is silver palladium paste, etc.
Bake at a temperature of about 900 ℃. Firing thickness is 5-10μ
It is about m. At this time, each of the electrode holes 45 to 48 is sucked by using the vacuum of the vacuum chuck so that the silver-palladium paste being printed can be transmitted along the inner wall surface of each of the electrode holes 45 to 48.
Pour into 48. In the manufacturing process (2B), the substrate 11
The electrode pattern 40 including the electrode terminals 41 to 44 is screen-printed on the back surface (rear surface 15) of FIG. The printing material is the same silver-palladium paste used in the manufacturing step (2A), and the firing method and firing thickness are the same as those in the manufacturing step (2A). Also in this case, the manufacturing process (2A)
Similarly, each of the electrode holes 45 to 48 is sucked by using the vacuum of the vacuum chuck, and the silver-palladium paste being printed is poured into each of the electrode holes 45 to 48 so as to be transmitted through the inner wall surface. By pouring by vacuum suction from the facing surface 13 side and the back surface 15 side, conductive portions 51 to 54 are formed on the inner wall surfaces of the electrode holes 45 to 48, respectively, as shown in the cross section of FIG. Through holes are formed. Of the through holes formed in each of the electrode holes 45 to 48, the electrode hole 48 for the common electrode 34 is formed on one side by the conductive paste 25 (see FIG. 4) inserted in the manufacturing step (4) described later. Although the entrance of the other is blocked, the other central electrode 31, reference electrode 32,
At least one of the electrode holes 45 to 47 for the shield electrode 33 has a low-pressure port for introducing the atmosphere into the space 30 and has inlets on both sides thereof open.

In the manufacturing process (2C), the overcoat glass 21 is printed on the facing surface 13 of the substrate 11 in the arrangement shown in FIGS. The printing material is passivation glass, etc., and is baked in a continuous furnace at a temperature of 700 to 900 ° C.
The calcined thickness is about 20 to 28 μm. Manufacturing process (2D)
In the above, the high melting point glass 22 functioning as a spacer on the overcoat glass 21 (arrangement shown in FIGS. 1 and 4).
To print. The printing material is glass paste, which is fired at a temperature of about 700-900 ° C in a continuous furnace. The calcined thickness is about 20 to 50 μm, but this thickness varies depending on the range of the pressure sensor. In the manufacturing process (2E), the manufacturing process (2D) is further performed on the overcoat glass 21.
The low-melting-point glass 23 for bonding is arranged so as to surround the inside and the outside of the high-melting-point glass 22 printed in, that is, the arrangement that extends over both sides of the high-melting-point glass 22 (the arrangement shown in FIGS.
Print and dry. At this time, printing is performed with a mask excluding this portion so that the space 24 is formed at the corresponding position of the electrode hole 48 at the same time. The printing material is glass paste, and the dry thickness is about 20 to 50 μm, but this thickness varies depending on the measurement range of the pressure sensor.

On the other hand, in the manufacturing process (2F), a circular common electrode as shown in FIG. 2 is formed on the facing surface 14 of the diaphragm 12.
Print 34. The printing material is, for example, gold resinate, and is baked at a temperature of about 700 to 900 ° C. in a continuous furnace.
The calcined thickness is about 0.5 to 1 μm. Manufacturing process (2
In G), the same material as the low melting point glass 23 for bonding printed in the manufacturing process (2E) is printed on the facing surface 14 of the diaphragm 12 in the arrangement shown in FIGS. 1 and 4, and dried. The dry thickness is about 20 to 50 μm, but it depends on the measurement range of the pressure sensor. The low-melting glass 23 is fired in the next manufacturing step (3), and the thickness after firing is greatly reduced with respect to the dry thickness. Further, the printing of the low melting point glass 23 in either the manufacturing step (2E) or the manufacturing step (2G) is omitted, and the low melting point glass 23 is printed only on one side of the substrate 11 side or the diaphragm 12 side to perform the joining. In some cases,
In short, the low melting point glass 23 is printed on at least one side so as to have the cross-sectional arrangement shape shown in FIG. 4 after firing in the next manufacturing step (3).

Subsequently, in the manufacturing process (3), the substrate 11 and the diaphragm 12 are aligned so that the facing surfaces 13 and 14 face each other, and the low melting glass 23 is fired to bond them. The firing temperature is about 600-700 ° C. After that, in the manufacturing process (4), the conductive paste 25 (see FIG. 3) is attached to the tip of a thin wire or the like through the through hole formed in the electrode hole 48, and is inserted into the space 24. And the electrode terminals 44 provided on the back surface 15 of the substrate 11 are electrically connected. Firing is usually performed at a temperature of 600 ° C or lower. Finally,
In the manufacturing process (5), each circuit path on the back surface 15 of the substrate 11
One-chip IC where one end of 61 to 64 is concentrated
A pin for connecting the measuring circuit 65 inside the one-chip IC 60 is soldered to a position corresponding to the position of the foot of 60, and the one-chip IC 60 is mounted here.

According to such a first embodiment, there are the following effects. That is, the electrode on the substrate 11 side is the central electrode 3
1, the reference electrode 32, and the shield electrode 33 are divided into three, so that the influence of the ceramics which is the material of the substrate 11 near the joint 20 and the low melting point glass 23 forming the joint 20 is the outermost, that is, the joint 20. Side condenser 37 (capacitance CS)
Only the internal capacitors 35, 36 (capacitance
CM, CR) may not be affected by these. That is, due to the presence of the joint portion 20, the line of electric force connecting the shield electrode 33 and the common electrode 34 is formed so as to bulge outward, and the electrostatic capacitance CS causes a change in the dielectric constant due to the humidity change of the ceramics or the low melting point glass 23. On the other hand, the lines of electric force connecting the central electrode 31 and the reference electrode 32 to the common electrode 34 are normally straight lines formed in the space 30, and the capacitances CM and CR of the space 30 are affected. It will be affected only by the dielectric constant of the atmosphere. Therefore, the shield electrode 33 on the outermost side, that is, the joint 20 side is not used for measurement but is used for grounding, and the central electrode 31 and the reference electrode 32 on the inner side are used for measurement, whereby the above-mentioned ceramics and low melting point are measured. It is possible to perform accurate measurement without being affected by the glass 23 and the like.

Further, as shown in FIG. 5, the voltage V at the output terminal 78 is V∝VO = {(CR-CM) / (CR +) by the circuit 70.
CM)} × VI, and the capacitance C of each capacitor 35, 36
Since the output signal related to the ratio of the sum and difference of M and CR can be obtained, the permittivity of the atmosphere in the space 30 changes under the influence of temperature, humidity, etc., and the capacitance CM, Even if the CR changes, this effect can be corrected, and in addition to the effect of providing the shield electrode 33 described above, the measurement accuracy can be further improved. That is, capacitance C
M and CR are the electrode area AM and AR, the electrode distance is DM,
If DR and the amount of change are DMP and DRP (DMP> DRP), CM = ε × AM / (DM-DMP) and CR = ε × AR / (DR-DRP), where the dielectric constant ε is Even if it changes due to the influence of the temperature and humidity of the atmosphere in the space 30, since the voltage V of the output terminal 78 is the ratio of the sum and difference of the capacitances CM and CR, this influence is canceled. be able to.

Further, since the central electrode 31 is formed in a circular shape and the reference electrode 32 and the shield electrode 33 are formed in a closed annular shape, it can be easily manufactured. Further, since the common electrode 34 is formed in a circular shape, the substrate 11 and the diaphragm are
Since it is possible to perform the joining work without considering the directionality of the joining with 12, it is possible to facilitate the manufacturing. Then, the outer edge portion 38 of the circular common electrode 34
Is located outside the outer edge position of the outermost shield electrode 33 on the substrate 11 side, so that the electrode terminal 44 for the common electrode 34 can be easily taken out from the back surface 15 of the substrate 11. can do.

Further, since the shield electrode 33 is provided, when the resistance of the ceramics which is the material of the substrate 11 or the edge surface resistance of the low melting point glass 23 which constitutes the joint portion 20 is lowered with the increase of humidity, the reference is used. A leak current (leak current) flowing from the electrode 32 to the common electrode 34 can be absorbed by the shield electrode 33. Since the shield electrode 33 is not used for measurement, the influence of humidity on measurement can be reduced by installing the shield electrode 33.

The joint 20 has a high melting point glass 22 which functions as a spacer, and a low melting point glass 23 for bonding is arranged around the high melting point glass 22. Adjusting the board 11 and diaphragm
It is possible to easily set the distance between the electrodes 12 and 12, that is, the inter-electrode distance T in parallel and at a predetermined distance. In addition, the joint 20
Has an overcoat glass 21, which increases the edge distance between the shield electrode 33 and the common electrode 34 and increases the edge resistance, so that the leakage current between them can be reduced. Then, by printing this overcoat glass 21 so as to cover not only a part of the shield electrode 33 but also the central electrode 31 and the reference electrode 32, when the diaphragm 12 is excessively deformed, these electrodes and the common electrode 34 are Can be prevented from being short-circuited. Also,
Since the overcoat glass 21 covers a part of the shield electrode 33 and a part of the reference electrode 32 side is directly exposed to the atmosphere of the space 30, a structure that easily absorbs a leak current from the reference electrode 32 is generated. Has become. Therefore, the joint portion 20 by the shield electrode 33 described above
The effect of preventing the leakage current from the reference electrode 32 to the common electrode 34 along the edge surface of the can be improved. Further, since the space 24 is provided in advance in the low melting point glass 23 and the overcoat glass 21, it is possible to prevent the inconvenience that the conductive paste 25 for extracting the common electrode 34 to the outside protrudes into the space 30. can do.

In the electrode pattern 40 provided on the back surface 15 of the substrate 11, the circuit paths 63A and 63B connected to the electrode terminal 43 for absorbing the shield electrode 33 are connected to the circuit path including the electrode terminal 44 for the common electrode 34. It is arranged so as to surround the path 64 and includes a circuit path 61 including an electrode terminal 41 for the central electrode 31 and a circuit path 62 including an electrode terminal 42 for the reference electrode 32, and an electrode terminal 44 for the common electrode 34. The circuit path 64 and the circuit paths 63A and 63B serving as ground electrodes are separated from each other. Therefore, when the humidity of the atmosphere in contact with the electrode pattern 40 increases, the circuit path for the central electrode 31
The leak current from the circuit path 62 for the 61 and the reference electrode 32 to the circuit path 64 for the common electrode 34 can be absorbed by the circuit paths 63A and 63B for the shield electrode 33, and accurate measurement can be performed. .

Further, by reducing the influence of atmospheric humidity change by disposing the electrode pattern 40 as described above, in order to obtain a large capacitance change in which the influence of leakage current is negligible as in the conventional case, a pressure sensor is used. It is possible to prevent the inconvenience that the size becomes large. Furthermore, it is not necessary to seal the atmosphere in contact with the electrode pattern 40 in order to reduce the influence of the humidity change as in the conventional case, and it is possible to reduce the sealing parts and the sealing process, so that the cost can be reduced. Since the space for sealing is unnecessary, the pressure sensor can be downsized also from this point. The rear surface of the substrate 11 is covered so as to cover the electrode pattern 40, except for at least one of the through holes formed in the electrode holes 45, 46, 47 which are low voltage ports.
By applying a process of dropping molten resin or the like to 15 and closing it, that is, so-called potting, it can be used even in a severe environment. As the potting material, polyurethane resin or the like can be used. Further, such an arrangement of the electrode pattern 40 can reduce the influence of the disturbance as described above, and thus a weak current can be detected. Therefore, since the amplification sensitivity of the amplification element can be increased and the pressure conversion element 10 can be made to have a minute capacitance, the pressure sensor can be downsized.

Further, since the passage (low pressure port) for guiding the atmosphere serving as the reference pressure for measurement to the space 30 is secured by utilizing the through holes formed in the electrode holes 45, 46, 47,
The low-pressure port can be secured only by the manufacturing steps (2A) and (2B) in which the electrode pattern 40 on the back surface 15 side of 11 and the electrodes on the opposite surface 13 side are electrically connected to each other. The manufacturing process can be omitted.

Furthermore, all the measuring circuits 65 are one-chip ICs.
Put this one-chip IC60 in the inside of 60 and the back of the board 11.
Since it is mounted directly on the electrode pattern 40 on 15, compared to the case where a measurement circuit composed of a large number of components is mounted on a printed circuit board provided as a separate member as in the conventional example,
It is possible to reduce the number of parts that make up the measurement circuit, and to omit the members such as the printed circuit boards that mount them.
The number of parts can be reduced. As a result, the number of steps for mounting the components that make up these measurement circuits, the printed circuit board, and the like can be reduced, and the manufacturing process can be simplified. In addition, the installation space for the printed circuit board and the like can be omitted, and the pressure sensor can be miniaturized. be able to.

Further, the electrode pattern 40 on the rear surface 15 side of the substrate 11
Since the central electrode 31, the reference electrode 32, the shield electrode 33, and the connection terminal 39 on the facing surface 13 side are printed with a silver-palladium paste having a low viscosity and a good elongation, it is possible to reliably conduct these. It can be carried out. At this time, in the conduction by the gold resinate and the silver-palladium paste, which is generally performed as a combination of these, since different materials are used and the thickness of the gold resinate after firing is thin, a portion where these different materials are in contact with each other is used. , There is a possibility that the so-called gold side erosion phenomenon may occur due to the fact that the gold resinate, which is the material on one side, diffuses into the silver-palladium paste, which is the other material, and disappears. In the example, this can be prevented in advance. Further, both sides of the electrode pattern 40 on the back surface 15 side of the substrate 11, the central electrode 31, the reference electrode 32, the shield electrode 33, and the connection terminal 39 on the facing surface 13 side are printed with gold resinate, and each electrode hole 45 is printed. When through hole processing of ~ 48,
Since the gold resinate is thinly finished, the printed amount of the conductive parts 51 to 54 may be extremely small and the conductive property may be incomplete, but the through-hole processing using silver palladium paste on both sides as in the present embodiment is more reliable. Can be conducted to.

FIG. 7 and FIG. 8 show a capacitance type pressure conversion element 100 according to a second embodiment of the present invention. The pressure conversion element 100 has substantially the same configuration, operation, and the like as the above-described first embodiment except for the measurement circuit incorporated in the one-chip IC, and the manufacturing method is also the same. Therefore, the same portions are denoted by the same reference numerals, detailed description thereof will be omitted, and only different portions will be described. FIG. 7 shows the body 10A of the pressure conversion element 100.
And each condenser 35, 36, formed in this main body 10A
Measuring circuit 165 for measuring changes in capacitance CM, CR, and CS of 37
The connection state with is shown, and the measurement principle is shown in FIG. Also, on the back surface 15 of the substrate 11, the same electrode pattern 40 as that of the first embodiment shown in FIG. 3A is formed, and the one-chip IC 160 in which the measuring circuit 165 is built in this electrode pattern 40. Is installed directly.

In FIGS. 7 and 8, the measuring circuit 165 is provided with an oscillator (AC power supply) 170, and the voltage from the oscillator 170 is passed through the operational amplifiers 171 and 172 as an accurate positive / inverted signal to the capacitor 35 (electrostatic capacitance CM), condenser
Applied to 36 (Capacitance CR). At this time, the condenser
The voltages VM and VR generated between both electrodes of 35 and 36 are
The values dVM / dt = IM / CM and dVR / dt = IR / CR are satisfied, and the currents IM and IR flowing through the capacitors 35 and 36 are values proportional to the capacitances CM and CR. The signal applied by the oscillator 170 may be a sine wave or a triangular wave. As a result, an operational amplifier that is an amplification element
A current I proportional to the difference in capacitance (CM-CR) between the capacitors 35 and 36 flows through the input terminal 174 of 173. Therefore, the capacitances CM and CR are set to be substantially equal to each other, and the change amounts ΔCM and ΔCR of the capacitances CM and CR according to the deflection of the diaphragm 12 due to the pressure of the measurement fluid are set to ΔCM> ΔCR. By arranging the condensers 35 and 36, that is, the condenser 35 is placed on the center side where the deflection amount of the diaphragm 12 is large.
By arranging (capacitance CM), an output signal as a function of the pressure of the measurement fluid acting on the pressure receiving surface 16 of the diaphragm 12 can be obtained at the output terminal 175 of the operational amplifier 173.

Dotted lines in FIG. 7 indicate lines of electric force running between the electrodes, and the lines of electric force in such a state are formed while reversing the direction at a constant cycle according to the signal of the oscillator 170. It is like this. Electrode terminal 43 for shield electrode 33
The circuit paths 63A and 63B (see FIG. 3) that are electrically connected to each other are arranged so as to surround the circuit path 64 including the electrode terminal 44 for the common electrode 34 (corresponding to the dotted line in FIG. 8), and are connected from the grounding terminals 176 and 177 to the buffer. Connected to element 178 and grounded. These grounding terminals 176 and 177 are the input terminals 174 of the operational amplifier 173.
And the signal application terminals 179,18 from each operational amplifier 171,172.
It is arranged so that it is separated from 0.

According to the second embodiment as described above, it is possible to obtain the effects of high-accuracy measurement, downsizing of the pressure sensor, and the like, substantially in the same manner as the first embodiment. In the second embodiment, the difference in capacitance between the capacitors 35 and 36 (CM-CR)
Since the output is detected as, it is not possible to avoid the influence of the change in the dielectric constant due to the temperature change or the humidity change of the atmosphere in the space 30 as in the first embodiment described above, but since the shield electrode 33 is provided, Similar to the one embodiment, the influence of the ceramics, the low melting point glass 23, etc. can be avoided. Then, in the second embodiment, each of the above effects can be realized with a simple circuit as compared with the first embodiment described above.

9 to 11 show a capacitance type pressure conversion element 200 according to the third embodiment of the present invention.
The pressure conversion element 200 has substantially the same configuration, operation, and the like as those of the first and second embodiments described above except for the measurement circuit incorporated in the one-chip IC and the electrode pattern on the back surface of the substrate. Are also the same. Therefore, the same portions are denoted by the same reference numerals, detailed description thereof will be omitted, and only different portions will be described. FIG. 9 shows the detailed structure of the electrode pattern 240 of the pressure conversion element 200, and FIG. 10 shows the main body 10A of the pressure conversion element 200 and the capacitors 35, 36, 37 formed in the main body 10A. Shows the connection state with the measurement circuit 265 that measures changes in the capacitances CM, CR, and CS of
FIG. 11 shows the measurement principle.

In FIG. 9, the substrate 11 of the pressure conversion element 200 is shown.
An electrode pattern 240 different from those of the first and second embodiments described above is provided on the back surface 15 of the device, and the one-chip IC 260 is directly mounted on the electrode pattern 240. 9 is a state before mounting the one-chip IC 260. Electrode pattern 24 of the third embodiment
0 is each electrode terminal 41, 4 for the central electrode 31, the reference electrode 32, the shield electrode 33, and the common electrode 34 at the same position as the electrode pattern 40 (see FIG. 3) of the first and second embodiments.
2, 43, 44 of which electrode terminals 41, 42, 4
Each of the key-shaped circuit paths 261, 262 and 264 led from 4 to the position of the pin (pin) of the one-chip IC 260 also has the same arrangement shape as the circuit paths 61, 62 and 64 of the first and second embodiments. Further, the circuit path 263A formed in a ring shape on the outer edge portion of the back surface 15 of the substrate 11 that is electrically connected to the electrode terminal 43 is also the first,
It has the same layout shape as the circuit path 63A of the second embodiment. However, the electrode pattern 240 of the third embodiment has a circuit path 263B having an arrangement shape different from the circuit path 63B of the electrode pattern 40 of the first and second embodiments. That is, the circuit path of the electrode pattern 40 of the first and second embodiments
63B is connected to the inner side of the left side portion of the ring-shaped circuit path 63A in FIG. 3 and is arranged so as to surround the electrode terminal 44 for the common electrode 34 and the circuit path 64. The circuit path 263B of the example electrode pattern 240 is connected to the inner protrusion of the ring-shaped circuit path 263A on the right side in FIG. 9 and includes the electrode terminal 41 for the central electrode 31.
Also, the circuit paths 262 including the electrode terminals 42 for the reference electrodes 32 are arranged so as to individually surround the circuit paths 262 at predetermined intervals. In addition, this circuit path 263B is
The grounding terminal 27, which will be described later, has passed through the position of the foot of the one-chip IC 260, which is located alternately with the tips of the 261,262,264.
It is designed to be connected to 7,278,279. Each circuit path 26 electrically connected to the electrode terminal 43 for these shield electrodes 33
3A and 263B are grounded. Therefore, the common electrode 34
Circuit path 264 including the electrode terminal 44 for the central electrode 31 and the circuit path 261 including the electrode terminal 41 for the central electrode 31 and the reference electrode
The circuit path 262 including the electrode terminal 42 for 32 and the circuit path 263A, 263B serving as ground electrodes are separated from each other. Therefore, it is possible to reduce the influence of an increase in leak current due to a decrease in insulation resistance between them.

10 and 11, the measuring circuit 265 according to the third embodiment is the measuring circuit 16 of the second embodiment.
Unlike 5, the power is applied from the common electrode 34 side. The measuring circuit 265 is provided with an oscillator (AC power supply) 270, and the signal of this oscillator 270 is transferred to the capacitor 35 (electrostatic capacitance CM),
A common electrode 34 is applied to a capacitor 36 (capacitance CR) to excite them and a current I is passed. At this time, currents IM and IR proportional to the capacitances CM and CR flow to the input terminals 271 and 272. The input signals are amplified by the operational amplifiers 273 and 274, respectively, and the difference between them is calculated by the calculation circuit 275 and output to the output terminal 276. This makes it possible to obtain an output signal at the output terminal 276 as a function of the pressure of the measurement fluid acting on the pressure receiving surface 16 of the diaphragm 12. The oscillator 270
The signal applied by can be a sine wave or a triangular wave. Here, showing an example of specific numerical values,
If the pressure sensor has a specification of 0 to 2000 mmH ₂ O, an AC signal is applied from the oscillator 270 and each capacitance
When CM and CR are set to 30 pF, for example, the capacitance CM of the capacitor 35 usually changes by 6 to 8 pF due to the deflection of the diaphragm 12, while the capacitance CR of the capacitor 36 is 1 to 2 pF.
F changes, and the difference between both capacitances is about 5 to 6 pF.

Dotted lines in FIG. 10 indicate lines of electric force running between the electrodes, and the lines of electric force in such a state are formed while reversing the direction at a constant cycle according to the signal of the oscillator 270. It is like this. Electrode terminal 43 of shield electrode 33
The circuit paths 263A and 263B (see FIG. 9) that are electrically connected to each other surround the circuit path 261 including the electrode terminal 41 for the central electrode 31 and the circuit path 262 including the electrode terminal 42 for the reference electrode 32 separately. They are arranged (corresponding to the dotted line in FIG. 11), are connected to the buffer element 280 from the grounding terminals 277, 278, 279 and are grounded. These ground terminals 277, 27
8,279 are arranged so as to separate the signal application terminal 281 from the oscillator 270 and the input terminals 271 and 272 to the operational amplifiers 273 and 274, respectively. Therefore, it is possible to reduce the influence of an increase in leak current due to a decrease in insulation resistance between them.

According to the third embodiment as described above, it is possible to obtain the effects of high-accuracy measurement, downsizing of the pressure sensor, and the like, as in the first and second embodiments. Further, in the third embodiment, since the output is detected by taking the difference between the currents IM and IR by the arithmetic circuit 275, the dielectric due to the temperature change or humidity change of the atmosphere in the space 30 as in the first embodiment described above is detected. Although the influence of the rate change cannot be avoided, since the shield electrode 33 is provided, the influence of the ceramics, the low melting point glass 23 and the like can be avoided as in the first embodiment. Then, in the third embodiment, each of the above effects can be realized with a simple circuit as compared with the first embodiment described above.

The present invention is not limited to the above-described embodiments, but includes other configurations that can achieve the object of the present invention, such as the following modifications and the like. . That is, in each of the embodiments, through holes are applied to all of the central electrode 31, the reference electrode 32, and the electrode holes 45 to 47 for the shield electrode 33 on the side of the substrate 11, but all the electrode holes 45 to The inlets on both sides of 47 may be opened and used as passages (low-pressure ports) for introducing the atmosphere into the space 30, or the inlets on the back surface 15 side of some of the electrode holes may be closed, and both sides of the remaining electrode holes may be closed. The entrance of each of these electrode holes 45 ~
At least one of the through holes formed in 47 should be a passage. Further, when the pressure conversion element 10 is covered with a casing and a passage for communicating the space 30 with the outside is further formed in this casing, considering the arrangement of the passage formed in the casing, for example, , The center electrode 31, the reference electrode 32 electrode holes 45, 46 of the rear side 15 side entrance is blocked, the shield electrode 33 electrode hole
The inlet on the rear surface 15 side of 47 may be connected to a passage formed in the casing to form one continuous passage.

Further, the conducting portions 51 to 53 of the electrode holes 45 to 47 of each of the embodiments are formed by vacuum suction from both sides (see FIG. 6), but the invention is not limited to this, and for example, It may be formed of metal fittings such as eyelets through which the shoelace is passed. In short, it is formed to have a cross-sectional shape as shown in FIG. 6, and it is possible to form a through hole which serves as a passage for guiding a fluid such as the atmosphere into the space 30, and It suffices that the electrodes 31 to 33 and the electrode terminals 41 to 43 be electrically connected to each other with certainty.

The shape of each of the electrodes 31 to 34 in each of the above embodiments is arbitrary, and may be, for example, a polygonal shape or a polygonal annular shape instead of a circular or annular shape. The number of divisions is not limited to three, and may be arbitrary. Furthermore, the method of forming the electrodes 31 to 34 and the method of forming the bonding portion 20 do not need to be the method shown in the manufacturing process of each of the embodiments, for example, the electrodes 31 to 34 are not screen-printed, It may be formed by other commonly used means such as plating, etching and sputtering. In addition, the electrode patterns 40, 240 formed on the back surface 15 of the substrate 11 of each of the embodiments
The arrangement shape is arbitrary, and each of the electrode terminals 41 to 43 for the central electrode 31, the reference electrode 32, and the shield electrode 33 on the substrate 11 side.
It may be configured to include. Furthermore, the substrate 11 of the present invention
Numerical values such as the thickness of the diaphragm 12, the thickness of each electrode 31 to 34, the distance between the electrodes, the capacitances CM, CR, CS of the capacitors 35 to 37, the specifications of the pressure sensor, etc. It is not limited to the numerical values described, and may be appropriately determined according to the measurement target, the measurement environment, and the like.

In each of the above-described embodiments, the space 30 is set to the atmospheric pressure and the pressure of the measurement fluid is detected as a gauge pressure. The pressure difference between the pressure in the space 30 and the pressure applied to the pressure receiving surface 16 may be detected. Further, the measurement fluid (fluid acting on the pressure receiving surface 16), which is the pressure measurement target of the pressure sensor including the pressure conversion element 10 of the present invention, may be liquid or gas.

[0048]

As described above, according to the present invention, the inside of the space formed between the substrate and the elastic diaphragm is utilized by utilizing the through hole formed in the central portion of the electrode hole for taking out the electrode to the outside. Since a fluid such as the atmosphere that serves as a reference pressure for pressure measurement is introduced to the pressure sensor, the structure of the pressure sensor can be simplified, and the manufacturing process can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is an exploded view of the first embodiment.

FIG. 3 is a configuration diagram showing an electrode pattern on the back surface of the first embodiment.

FIG. 4 is a sectional view showing a main part of the first embodiment.

FIG. 5 is a configuration diagram showing a measurement circuit of the first embodiment.

FIG. 6 is a sectional view showing another main part of the first embodiment.

FIG. 7 is a configuration diagram showing a second embodiment of the present invention.

FIG. 8 is an explanatory diagram of a measuring circuit according to a second embodiment.

FIG. 9 is a configuration diagram showing an electrode pattern on the back surface of a third embodiment of the present invention.

FIG. 10 is a configuration diagram showing a third embodiment.

FIG. 11 is an explanatory diagram of a measuring circuit according to a third embodiment.

FIG. 12 is a sectional view showing a conventional example.

[Explanation of symbols]

 10,100,200 Pressure conversion element 11 Substrate 12 Diaphragm 20 Joint 30 Space 31 Center electrode 32 Reference electrode 33 Shield electrode 34 Common electrode 41 Electrode terminal for center electrode 42 Electrode terminal for reference electrode 43 Electrode terminal for shield electrode 45 to 47 Through Electrode holes with holes 51-53 Conductive part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigemitsu Ogawa 2-14-2 Chuonishi, Ueda City, Nagano Prefecture (72) Inventor Fujino Tanaka 5463, Otowa, Higashibu-cho, Oka-gun, Nagano Prefecture Inventor Munenori Tsuchiya 694-1 Furusato, Ueda City, Nagano Prefecture (72) Inventor Daiji Uehara 1-9-4 Saikimachi, Ueda City, Nagano Prefecture (72) Kenji Nagasawa 160-5 Ueda, Ueda City, Nagano Prefecture

Claims (3)

[Claims] 1. A thick-walled substrate, and a thin-walled elastic diaphragm that is arranged facing the substrate at a predetermined interval,
A pressure sensor provided with electrodes facing each of the facing surfaces of the substrate and the elastic diaphragm, the pressure sensor detecting a pressure applied to the elastic diaphragm by a change in capacitance between the electrodes. The electrode terminal for the side electrode is provided on the surface opposite to the electrode installation surface of the substrate, so that the conducting portion for conducting the electrode on the substrate side and the electrode terminal for this electrode penetrates the substrate. A through hole is formed in the inner wall surface of the provided electrode hole, and a through hole is formed in the central portion of the electrode hole so as to be surrounded by the conducting portion. The through hole is formed between the substrate and the elastic diaphragm. A pressure sensor characterized by being a passage for guiding a fluid such as the atmosphere, which serves as a reference pressure for pressure measurement, into the space. 2. The pressure sensor according to claim 1, wherein the conductive portion is made of the same material as that of the electrode on the substrate side and the material of the electrode terminal for this electrode, and When forming each electrode terminal for an electrode, vacuum suction the material on each side from the opposite side of the electrode hole so as to propagate along the inner wall surface of the electrode hole, and conduct the material on both sides inside the electrode hole. The pressure sensor is characterized by being formed by. 3. The pressure sensor according to claim 2, wherein the material is silver palladium paste.