JPH08233670A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE: To stably detect pressure of a corrosive and high temperature pressure measuring object medium by filling a pressure transmitting flow medium in an airtight space surrounded by a case, and slidably installing a pressure transmitting part in a pressure introducing port to be measured. CONSTITUTION: A detecting element part 10 is formed by joining a silicon substrate 1 having a diaphragm part 11 deformed by pressure to be measured and an insulating board 2 where an electrode part 31 is formed on a surface opposed to the diaphragm part 11 by electrostatic coupling. The whole element part 10 is adhered to a lower inner wall surface of a lower side case 5 by an adhesive 90, and the upper and lower cases 4 and 5 are joined together by ultrasonic welding or the like, and a pressure transmitting medium 7 is filled in an airtight space 70. A pressure transmitting slidingly movable member 6 is installed in a pressure introducing port 41 of the case 4, and prevents the medium 7 from leaking to a measuring object side medium 12. Pressure of the medium 12 applies pressure to a member 6, and this pressure is transmitted to the medium 7, and the diaphragm 11 of the substrate 1 of the element 10 is deformed by this pressure, and capacitance of the element 10 is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor type pressure sensor used for detecting various pressures used in automobiles and pressure detection for industrial and home electric appliances. Regarding the improvement of.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional capacitive semiconductor pressure sensor. The detection element unit 10 is joined to the lower case 5 with an adhesive or the like. In the detection element unit 10, the silicon substrate 1 having the diaphragm portion 11 that is deformed by the measured pressure and the insulating substrate 2 are electrostatically joined. The detection element section 10 is formed by being joined so as to face each other. Here, the insulating substrate 2 is provided with an electrode portion 31 which is an electrode for forming an air condenser portion so as to face the diaphragm portion 11 of the silicon substrate 1 and has a reference pressure P.
A through hole 9 for detecting 2 is opened.

The diaphragm 11 of the silicon substrate 1 is deformed by receiving a pressure difference (ΔP = P ₁ -P ₂ ).
The capacitance value of the air capacitor formed between the silicon substrate 1 and the electrode portion 2 changes, and this change in capacitance is used as the output of the subsequent processing circuit (capacitance-frequency conversion circuit). Here, P ₁ is the pressure of the medium to be measured, and P ₂ is the reference pressure.

[0004]

The above-mentioned conventional method has the following problems. The structure of the conventional example can detect only the non-corrosive gas etc. (general air etc.) as the pressure to be measured, and other corrosive gas or general liquid (water etc.), There is a problem that the reliability of detection is significantly reduced. The reason is that when a corrosive gas or a liquid such as water enters the airtight space formed by the upper and lower cases, the electrode connection of the detection element part, particularly the end 32 of the electrode part 31 and the bonding wire 33 is performed. This is because the portion (see FIG. 3) is corroded and a fatal defect such as disconnection is caused.

On the other hand, regarding the upper limit of the temperature of the medium to be measured,
It is limited by the heat resistance of the electrode connection part of the above-mentioned detection element part, and the limit is usually about 150 ° C. Therefore, it was impossible to measure the higher temperature medium.

[0006]

In order to solve the above-mentioned problems, in the pressure sensor of the present invention, pressure transmission excellent in corrosion resistance and heat resistance is carried out in the airtight space formed by the upper and lower cases. A sliding member for filling the liquid medium for use and for transmitting the pressure of the external pressure medium to be measured to the pressure transmitting medium in the airtight space is attached to the inner wall portion of the pressure introducing port of the upper case. .

[0007]

As shown in FIG. 1, the pressure P1 of the measured medium 12 is
Applies a pressure to the sliding member 6 for pressure transmission of the pressure introducing port 41, and the pressure is transmitted to the medium 7 for pressure transmission, and finally, the diaphragm 1 of the silicon substrate of the detection element 10 is
1 is deformed and detected as a change in the capacitance of the capacitor of the detection element section. Here, by using a liquid having excellent corrosion resistance and heat resistance as the pressure transmitting medium, the electrode connection portion is shielded from the corrosive medium and from the high temperature medium, and the corrosive and high temperature The pressure of the medium to be pressure-measured can be stably detected.

[0008]

1 shows a semiconductor pressure sensor according to the present invention.
An example will be described. The detection element section 10 includes a silicon substrate 1 having a diaphragm section 11 that is deformed by a measured pressure,
The insulating substrate 2 having the electrode portion 31 formed on the surface facing the diaphragm portion is joined by electrostatic joining. The entire detection element unit 10 is adhered to the lower inner wall surface of the lower case with an adhesive 90. The upper and lower cases 4 and 5 are joined by means such as ultrasonic welding, the airtight space 70 is filled with the pressure transmitting medium 7, and the pressure introducing port 41 of the upper case is provided with a pressure transmitting slide. The moving member 6 is mounted to prevent the pressure transmitting medium 7 from leaking to the medium 12 to be measured.

The principle of pressure detection will be described below with reference to FIG. The medium to be measured 12 (liquid or gas) is in contact with the outer tip of the pressure transmitting sliding member 6, and the pressure of the medium to be measured 12 applies pressure to the pressure transmitting sliding member 6. This pressure is transmitted to the pressure transmitting medium 7, and this pressure deforms the diaphragm 11 of the silicon substrate 1 of the detection element 10 to change the capacitance of the detection element,
This change in capacitance is detected by the processing circuit in the subsequent stage, and the pressure of the medium to be measured 12 is detected. Here, the pressure transmitting medium 7
Is selected as a liquid medium having excellent corrosion resistance and high temperature resistance, such as silicone oil, which does not affect the respective materials of the exposed portion of the detection element portion. Further, the pressure transmitting sliding member 6 is made of a metal material (stainless steel or the like) or a resin material (PBT, PBT) having excellent corrosion resistance and high temperature resistance.
It is formed of DS or the like) and is mounted so as to be slidable on the inner wall of the pressure introduction port 41 of the upper case 4.

[0010]

As described above, according to the present invention, by protecting the detection element portion from the corrosive and high temperature medium to be measured,
Stable pressure detection of corrosive gases and liquids, which was previously impossible to measure stably, is now possible.
It is possible to provide a semiconductor pressure sensor that can stably detect the pressure of high temperature gas and liquid.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of a pressure sensor according to the present invention.

FIG. 2 is a cross-sectional view showing the structure of an example of a conventional pressure sensor.

FIG. 3 is an external perspective view of a detection element unit.

[Explanation of Codes] 1 Silicon substrate 2 Insulating substrate 4 Upper case 5 Lower case 6 Sliding member 7 Pressure transmitting medium 8 Lead terminal 9 Through hole 10 Detection element section 11 Diaphragm section 12 Medium to be measured (liquid, gas) 31 Electrode Part 32 End part (of electrode part) 33 Bonding wire 41 Pressure inlet 70 Airtight space 90 Adhesive

Claims (3)

[Claims] 1. A semiconductor pressure device comprising: a detection element portion formed by joining a silicon substrate having a diaphragm portion and an insulating substrate formed with an electrode portion; and a case for housing the detection element portion. In the sensor, a liquid medium for pressure transmission is filled in an airtight space surrounded by the case, and a member for pressure transmission is slidably attached to a measured pressure introduction port provided in the case. A semiconductor pressure sensor characterized in that 2. The semiconductor pressure sensor according to claim 1, wherein the medium for pressure transmission is a liquid having excellent corrosion resistance and high temperature resistance. 3. The semiconductor pressure sensor according to claim 1, wherein the sliding member for pressure transmission is made of a material having excellent corrosion resistance and high temperature resistance.