JPH04130670A - Electrostatic capacitance type pressure sensor - Google Patents

Abstract

PURPOSE:To obtain a small size electrostatic capacitance type pressure sensor having uniform performance by stacking necessary elements and packaging these elements into a case having lead terminals in the electrostatic capacitance type pressure sensor comprising a silicon diagphram, a glass base and an oscillation circuit IC. CONSTITUTION:An electrostatic capacitance type pressure sensor chip is formed by anode junction of silicon diagphram 3 and a glass base 2. At the interface between the silicon diagphram 3 and the glass base 2, electrodes are provided in both sides forming capacitance electrodes. The other surface of the glass base 2 of this sensor chip is bonded to the rear surface opposed to the circuit forming surface of an oscillation circuit IC 1. The other surface of the silicon diagphram 3 operates as a pressure receiving surface and a pressure receiving part is exposed to a case 4 providing holes at the position corresponding to the silicon diagphram 3. A pressure receiving aperture of case 4 is sealed by a gel membrane 6. A sensor as a whole may be integrated and reduced in size. Moreover, connection between the oscillating circuit IC and sensor is shortened and influence by floating capacitance and noise can also be reduced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a capacitive pressure sensor.

[Summary of the invention]

This invention is a capacitive pressure sensor consisting of a silicon diaphragm, a glass base, and an oscillation circuit IC.The above three elements are laminated and packaged in a case with lead terminals to make the sensor compact and uniform in performance. The purpose is to obtain a capacitive pressure sensor.

[Conventional technology]

Conventionally, as shown in FIG. 5, an oscillation circuit has consisted of a circuit block 8 made up of a plurality of elements, and has not been integrated into a one-chip IC.

The substrate constituting the oscillation circuit was connected inside the case 4 to a sensor chip consisting of a glass base 2 and a silicon diaphragm 3 using lead terminals 8. For example, a conventional structure is disclosed in Japanese Unexamined Patent Publication No. 58-198739.

[Problem to be solved by the invention]

However, in conventional capacitive sensor configurations, the oscillation circuit is placed close to the sensor chip and shielded within the same case. Therefore, the influence of external noise etc. is reduced. However, since the oscillation circuit was not integrated into a single chip IC, the wiring between elements was long and there was a lot of stray capacitance. In addition, if the capacitive pressure sensor chip is miniaturized,
While the capacitance of the sensor chip decreases, the stray capacitance increases relatively, making accurate sensing impossible.

SUMMARY OF THE INVENTION In order to solve these conventional problems, it is an object of the present invention to provide a small, high-performance electrostatic force sensor in which wiring between elements is shortened.

[Means to solve the problem]

Said! In order to solve the problem III, in the present invention, the oscillation circuit is integrated on a single chip [C], and is stacked together with a silicon diaphragm and a glass base, and housed in a case having lead terminals.

[Effect]

In the capacitive sensor configured as described above, the oscillation circuit is integrated into an IC. Furthermore, since the oscillation circuit IC is stacked together with the diaphragm and the glass base, it is possible to further reduce the planar space. Then, the connection between the sensor chip and the oscillation circuit IC, which are formed by bonding the diaphragm and the glass base, and the oscillation circuit IC.
The connection between the lead terminal and the lead terminal is shortened, reducing stray capacitance and reducing the effects of noise.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1 and 2 are a plan view and a sectional view showing a first embodiment of the present invention.

In FIG. 1, the lead terminal is made of a lead frame 5 and is insert molded into the case 4. The capacitive pressure sensor tinop is constructed by anodic bonding of a silicon diaphragm 3 and a glass base 2. Opposing surfaces of the silicon diaphragm 3 and the glass base 2 have t-scratches on both sides, forming capacitive electrodes. The other surface of the glass base 2 of this sensor chip and the back surface facing the circuit forming surface of the oscillation circuit ICI are bonded. The other surface of the silicon diaphragm 3 serves as a pressure-receiving surface, and is disposed with the pressure-receiving portion exposed to the case 4, which has a hole formed at a position opposite to the silicon diaphragm 3. Said case 4
The pressure-receiving opening is sealed with a gel-like member 6.

The stacked sensor chips and oscillation circuit ICI are each connected to a lead frame 5 for electrical connection.

As shown in FIG. 2, a part of the lead frame 5 is adhesively fixed to the base of the case 4, and the glass base side 2 of the sensor chip, in which the glass base and the silicon diaphragm are anodically bonded, is adhesively fixed to the base of the case 4. Fixed.

Since the surfaces to which the glass base 2 and the oscillation circuit ICI are bonded are each made of an insulator, a stacked arrangement is possible without electrical problems such as short circuits.

From the sensor chip, the electrodes provided on the opposing surface of the glass base are connected to the lead frame 5, and the electrodes of the oscillation circuit ICI are connected to the lead frame 5 for electrical connection.

FIGS. 4 and 5 are a plan view and a sectional view showing a second embodiment of the present invention.

As shown in FIG. 4, the surface of the silicon diaphragm 3 on the opening side of the case 4 becomes the pressure receiving surface, and the entire gel-like member 6
It is configured in a sealed manner.

〔Effect of the invention〕

According to the present invention, it is possible to bond the oscillation circuit IC and the silicon diaphragm through the glass base, and there is no need to arrange them separately on the case base in a two-dimensional manner. , it becomes possible to integrate the entire sensor and downsize it. Also, the oscillation circuit I
This has the effect that the connection between C and the sensor can be shortened and the effects of stray capacitance, noise, etc. can be reduced.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a first embodiment of the present invention, Fig. 2 is a sectional view thereof, Fig. 3 is a plan view showing a second embodiment of the invention, and Fig. 4 is a sectional view thereof; FIG. 5 is a sectional view showing a conventional example. Oscillation circuit RC glass base silicon diaphragm case lead frame gel encapsulant circuit block or more

Claims (3)

[Claims] (1) A capacitor bonded to a glass base with an electrode pattern on one side and a silicon diaphragm with a diaphragm-like thin part on a part and an electrode pattern on one side with the electrode patterns facing each other. a capacitive pressure sensor chip, an oscillation circuit connected to the capacitive pressure sensor chip, and a capacitive pressure sensor in which a pressure-receiving surface of a thick silicon diaphragm of the capacitive pressure sensor chip is pressure-sensitively sealed. A capacitive pressure sensor comprising: an oscillation circuit IC stacked and fixed on a glass base of the capacitive sensor chip. (2) The capacitive pressure sensor according to claim 1, comprising: a case having a pressure introduction port at the bottom; a lead terminal fixed to the case; and a pressure receiving surface fixed to the direction of the pressure introduction port of the case. a capacitive pressure sensor chip having a silicon diaphragm fixed in alignment with the direction of the oscillation circuit, an electrode pattern of the silicon diaphragm, and a connection means for connecting the electrode pad of the oscillation circuit IC and the lead terminal; A capacitive pressure sensor that has a gel-like sealant that seals the pressure-receiving surface. (3) In the capacitive pressure sensor according to claim 1, the capacitive pressure sensor chip has a glass base fixed to the circuit forming surface of the oscillation circuit IC, and the surface opposite to the circuit forming surface is fixed to the circuit forming surface of the oscillation circuit IC. an oscillation circuit IC fixed to the bottom of the case; a silicon diaphragm fixed to the opening of the case; an electrode pattern on the glass base; and a connection means connecting the electrode pad of the oscillation circuit IC and the lead terminal. and the silicon diaphragm, glass substrate, and oscillation circuit IC.
, and a capacitive pressure sensor having a gel-like sealing material that seals the connection means.