JPH0894470A - Capacitive pressure sensor - Google Patents

Abstract

PURPOSE: To ensure electric connection while facilitating the handling through a simple structure. CONSTITUTION: The capacitive pressure sensor comprises an insulator diaphragm 11 being applied with the pressure of fluid, a planar diaphragm side electrode formed on the rear side of the diaphragm 11, an insulator base board 12 disposed oppositely to the diaphragm 11 through a constant interval, and a base side electrode disposed oppositely to the diaphragm side electrode on the surface of the base board 12. The diaphragm side electrode and the base side electrode are extended respectively, to the side face parts thereof and a wiring 24 extends along the side face of the base board 12 to the rear side thereof before being connected with each extended part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance-type pressure sensor that guides fluid pressure to a diaphragm, detects its distortion as a change in capacitance, and electrically obtains a pressure value.

[0002]

2. Description of the Related Art In a conventional pressure sensor, as shown in FIG. 6, a pair of lead terminals 2 is used to electrically connect to an electrode on the base substrate 4 side and an electrode on the diaphragm 6 side. This lead terminal 2 is, as shown in FIG.
The lead wire 2 is inserted into the terminal hole 8 of the base substrate 4 together with the conductive paste 9 such as silver paste, and is electrically contacted with the electrode inside the pressure sensor.

[0003]

In the case of the above-mentioned conventional technique, the lead terminal 2 is bent as shown in FIG. 6 when the pressure sensor is attached to an externally formed circuit board or during transportation. There were times when it ended up. Then, when a force is applied in the direction of the arrow in FIG. 6 in the bent state, an extremely large force is relatively applied to the connection portion between the terminal hole 8 and the electrode shown in FIG. There was a risk of peeling. Moreover, since the electrical contact state becomes unstable due to this peeling, even if the connection is confirmed at the time of inspection by the tester, there is a possibility that contact failure may occur during actual use, which is a big problem in quality control.

The present invention has been made in view of the above problems of the prior art, and provides a capacitance type pressure sensor having a simple structure, reliable electrical connection and easy handling. With the goal.

[0005]

The present invention is directed to ceramics such as alumina or zirconia to which a fluid pressure is applied,
A diaphragm made of an insulator such as silicon or quartz, a diaphragm-side electrode formed on the back surface of this diaphragm by flat printing or vacuum deposition, and alumina or zirconia provided facing the diaphragm at a constant interval. And the like, and a base side electrode formed on the surface of the base substrate and similarly provided facing the diaphragm side electrode. The diaphragm side electrode and the base side electrode respectively have the diaphragm. And an extension portion extending to a side surface portion of the base substrate, and a capacitance type pressure sensor in which wiring extending along the side surface of the base substrate and connected to the extension portions and extending to the back surface side of the base substrate is formed. Is.

On the side surface of the base substrate, recesses are formed in the front and back directions, and a conductive paste such as Au, Ag or Ag-Pd is applied to the recesses and connected to the extension of each electrode to connect the wiring. It was formed. Further, a circuit element connected to the wiring is attached to the back surface side of the base substrate.

[0007]

In the capacitance type pressure sensor of the present invention, the base side electrode and the diaphragm side electrode are electrically connected to the external circuit by the wiring such as the conductive paste formed on the side surface of the base substrate. There is no such thing as being caught by an external member as described above, and there is no risk of connection failure due to external force. In particular, by providing this wiring in the concave portion on the side surface of the base substrate, the wiring is located mechanically and electrically more safely with respect to the external member.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show an embodiment of the present invention. A capacitance type pressure sensor 10 of this embodiment is a circular diaphragm 1 made of alumina to which a fluid pressure is applied.
One. The diaphragm 11 is formed to have a thickness of, for example, about 0.2 to 2.0 mm, and the measurement pressure is 100.
It is up to about kg / cm ² . Diaphragm 11
As shown in FIG. 5, a diaphragm-side electrode 13 formed in a circular shape in plan view is provided on the back surface of the. The diaphragm-side electrode 13 is formed by printing with a conductive paste such as gold, silver, or silver-palladium, or formed by vacuum evaporation.

The capacitive pressure sensor 10 of this embodiment is further provided with a circular base substrate 12 made of alumina so as to face the diaphragm 11 at a constant interval. As shown in FIG. 4, a base side electrode 14 formed by a similar method is provided on the surface of the base substrate 12 so as to face the diaphragm side electrode 13. The side auxiliary electrode 15 is also formed.

Diaphragm side electrode 13, base side electrode 1
4 and base-side auxiliary electrode 15, extension portions 16, 17, and 18 which are extension patterns formed by a similar method are formed from their outer peripheral portions, respectively. The extension portions 16, 17, and 18 linearly extend to the side surface portions of the diaphragm 11 and the base substrate 12, respectively.

The diaphragm 11 and the base substrate 12 are
A sealing agent 19 made of glass frit is provided on the peripheral edge of the diaphragm-side electrode 13 and the base-side electrode 14,
They are formed so as to face each other at a predetermined distance within a range of about 10 to 30 μm. The sealing agent 19 is mixed with, for example, ceramic beads of a certain size, in order to form the diaphragm 11 and the base substrate 12 at a certain distance.

Further, on the side surface of the base substrate 12, three concave portions 21, 22, 23 are formed linearly in parallel with each other in the front and back direction of the base substrate 12 on the outer periphery of the side surface. A conductive paste 24 of Au, Ag, Ag-Pd or the like is applied over the entire lengths of the recesses 21, 22, 23 to provide electrical wiring. And this recess 2
1, the extension 16 of the diaphragm-side electrode 13 shown in FIG.
The tip ends of the electrodes face each other, and the conductive paste 24 is applied between the diaphragm 11 and the base substrate 12 for electrical connection. In addition, the conductive paste 2 in the recesses 22 and 23
4, the extension parts 17 and 18 of the base side electrode 14 and the base side auxiliary electrode 15 shown in FIG. 4 are connected, respectively.

The pressure sensor 10 does not require a separate HIC substrate or the like, and the circuit pattern 25 is directly formed on the base substrate 12 as shown in FIG. To the circuit pattern 25, wirings of the conductive pastes 24 of the recesses 21, 22, 23, a dedicated IC 26 which is a CV conversion circuit as an electronic element, and a capacitor 27 are connected, respectively, and an input / output pad 28 is also provided. It is connected.

According to the capacitance type pressure sensor of this embodiment, the wiring of the conductive paste 24 provided in the recesses 21, 22, 23 of the base substrate 12 allows the electrodes 13, 1 to be formed.
Since 4 and 15 are connected to an external circuit, they are not bent or have a connection failure due to an external force unlike the conventional lead terminals. In addition, extension parts 16, 17, 18 from each electrode 13, 14, 15
The connection state of each recess 21, 22, 23 with the conductive paste 24 can be visually confirmed, and the inspection of the electrical connection is facilitated. Further, the circuit can be directly formed on the back surface of the base substrate 12 without the need for a separate HIC substrate.

The capacitance type pressure sensor of the present invention is
The present invention is not limited to the above embodiment, and the outer shape and the shape of the electrodes may be formed in a square or other polygonal shape in addition to the circular shape. The position of the recess and the wiring formed in the recess can be changed as appropriate, and the wiring may be directly formed on the side surface of the base substrate in addition to the recess. Furthermore, the wiring on the side surface of the base substrate may be a conductive paste, copper foil, or another conductive thin film formed. Further, the diaphragm may be zirconia, silicon, crystal, or the like, in addition to ceramics. Also, the base substrate may be an insulator such as zirconia other than alumina.

[0016]

EFFECTS OF THE INVENTION The capacitance type pressure sensor of the present invention is easy to handle because the connection between each electrode and the external circuit is achieved by the wiring provided on the side surface of the base substrate. As described above, there is nothing caught on an external member, and a connection failure does not occur due to an external force. Further, by forming the wiring in the concave portion on the side surface of the base substrate, the wiring does not come into contact with an external member, which is safer. Also, by forming the wiring with a conductive paste,
The work is easy and reliable wiring is possible, and the electrical connection can be made highly reliable. Further, a circuit pattern can be formed on the back surface of the base substrate and an electronic element can be attached, which contributes to downsizing of the device and cost reduction.

[Brief description of drawings]

FIG. 1 is a perspective view of a capacitance type pressure sensor according to an embodiment of the present invention.

FIG. 2 is a bottom view of the capacitance type pressure sensor of this embodiment.

FIG. 3 is a side view of the capacitance type pressure sensor of this embodiment.

FIG. 4 is a plan view of a base substrate on a base-side electrode formation surface of the capacitance type pressure sensor of this embodiment.

FIG. 5 is a plan view of the diaphragm on the diaphragm-side electrode forming surface of the capacitance type pressure sensor of this embodiment.

FIG. 6 is a perspective view of a conventional capacitance type pressure sensor.

FIG. 7 is a partially enlarged sectional view of a conventional capacitance type pressure sensor.

[Explanation of symbols]

 10 Capacitive Pressure Sensor 11 Diaphragm 12 Base Substrate 13 Diaphragm Side Electrode 14 Base Side Electrode 16, 17, 18 Extensions 21, 22, 23 Recess 24 24 Conductive Paste

Claims (4)

[Claims] 1. A diaphragm of an insulator to which a fluid pressure is applied, a diaphragm-side electrode formed flat on the back surface of the diaphragm, and a base substrate facing the diaphragm at a constant interval. And a base-side electrode formed on the surface of the base substrate so as to face the diaphragm-side electrode and provided in the same manner, and side surfaces of the diaphragm and the base substrate, which are formed by extending from the diaphragm-side electrode and the base-side electrode, respectively. And an extension portion extending to a portion, and one end connected to each extension portion along the side surface of the base substrate and the other end having a wiring extending to the opposite side of the diaphragm of the base substrate. Sensor. 2. The electrostatic capacitor according to claim 1, wherein a concave portion is formed on a side surface of the base substrate in a front and back direction, and the wiring connected to an extended portion of each electrode is formed in the concave portion. Capacitive pressure sensor. 3. The capacitance type pressure sensor according to claim 1, wherein the wiring formed on the side surface of the base substrate is formed by applying a conductive paste. 4. The capacitive pressure according to claim 1, wherein a circuit pattern connected to the wiring is formed on the back surface side of the base substrate, and an electronic element is attached to the circuit pattern. Sensor.