JP2000002607A - Gas pressure detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a gas pressure detecting device with high accuracy and high reliability by stably detecting pressure in gasses to be measured (LP gas and city gas). SOLUTION: A pressure sensor element 1 is supported above a protruding part 14 for setting the interval of the pressure introducing tube 4 of a sensor case 5 integrally molded with a lead from 3 and a pressure introducing tube (gas proof material) 4 via a gas-proof adhesive 2 to from a gas pressure detecting passage so as to be airtightly held. A pressure introducing part 16 to come into contact with a gas to be measured is formed of a rubber sealing material or gas-proof material. By this, it is possible to prevent material degradation due to a fluid to be measured. By applying the gas-proof adhesive evenly in thickness, the function of buffering stress is sufficiently demonstrated, and the stability of output is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting gas pressure of a gas to be measured such as LP gas, city gas and the like.

[0002]

2. Description of the Related Art A conventional semiconductor pressure sensing device of this type will be described with reference to FIG.

In FIG. 6, reference numeral 31 denotes an outer frame, reference numeral 32 denotes a pressure inlet, and reference numeral 33 denotes a semiconductor pressure sensor element. A diaphragm film having a thickness of about 10 μm provided by etching on a silicon substrate has a lowermost surface. A semiconductor resistor whose electric resistance value changes due to mechanical strain generated by receiving pressure is formed.

Reference numeral 34 denotes a pedestal, which is usually made of metal, glass, or the like having a coefficient of thermal expansion close to that of the semiconductor pressure sensor element 33, as a flexible buffer absorbing mechanical strain, and holding the semiconductor pressure sensor element 33. Have been used to be. Reference numeral 35 denotes a lead frame, which is a semiconductor pressure sensor element 3.
3 and the circuit board 38 are held and fixed to the sensor case 37.

[0005] Reference numeral 36 denotes a joining portion, where the pedestal 34 and the sensor case 37 are joined by a high temperature of about 200 ° C such as an adhesive or eutectic joining. The sensor case 37 is provided with a differential pressure hole 42 communicating with the atmosphere at the upper part.

Reference numeral 38 denotes a circuit board on which an electric circuit such as an amplifier circuit is formed; 39, an adhesive for bonding the outer frame 31 to the sensor case 37; 40, a resin mold obtained by molding the sensor case 37 with a plastic resin; The outside of the pressure sensor element 33 is coated with a sufficiently soft gel 41 so as not to cause an error in pressure transmission so that dust and moisture in the atmosphere do not directly contact.

[0007]

However, in the above-mentioned conventional gas pressure detecting device, the bonding portion 36 of the adhesive and the soft gel 41 are deteriorated in the gas to be measured (LP gas, city gas) and a stable pressure is obtained. There was a problem that detection could not be performed.

An object of the present invention is to realize a highly accurate and highly reliable gas pressure detecting device by performing stable pressure detection in a gas to be measured (LP gas, city gas).

[0009]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention relates to a method for measuring the stress of a pressure sensor element (diaphragm film) due to swelling and shrinking of a material when the material comes into contact with a gas to be measured (LP gas, city gas). It is configured so as to reduce the change in absorptivity.

As a result, a stable, highly accurate and highly reliable gas pressure detecting device in the gas to be measured (LP gas, city gas) can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a pressure sensor element for outputting a pressure-receiving strain of a pressure-receiving film as an electric signal, and a gas detection passage, wherein an outer periphery of the pressure-receiving film of the pressure sensor element is provided. A pressure introducing pipe for supporting the pressure sensor element, comprising a projection for setting a gap so that the applied thickness of the gas-resistant adhesive on the adhesion surface is uniform, and a circuit for transmitting an electric signal from the pressure sensor element; A lead frame for transmitting to the substrate, a circuit substrate for adjusting and amplifying an electric signal from the pressure sensor element based on output / temperature characteristic data of the pressure sensor element, and transmitting the adjusted signal to the outside of the device; A pressure chamber having a pressure adjustment hole for opening the pressure receiving surface to the atmosphere is provided in a space on the non-pressure receiving surface side through a gel-like filler material that air-tightly blocks the pressure receiving surface and the non-pressure receiving surface of the pressure sensor element. Gas pressure detector It is obtained by the.

The portion where the fluid to be measured (LP gas, city gas) comes into contact is made of a gas-resistant rubber seal material and a gas-resistant material, so that material deterioration due to the fluid to be measured (LP gas, city gas) is prevented. In addition, by making the applied thickness of the gas-resistant adhesive uniform, an effect of sufficiently exhibiting a stress buffering function and stabilizing the output can be realized.

According to a second aspect of the present invention, there is provided a gas detection device, further comprising a projection for setting a distance between the pressure introduction pipes, provided on the pressure sensor element. By uniformizing the amount, position, and condition of the adhesive to the pressure sensor element, the stress on the sensor chip generated by external stress (temperature, humidity, etc.) is uniformed and reduced, and the output is stabilized. It has the effect of doing.

According to a third aspect of the present invention, there is provided a gas pressure detecting device, further comprising a supporting spacer provided with the interval setting projection between the pressure sensor element and the pressure introducing pipe. By providing a supporting spacer, the shape of the interval setting convex portion, the material, the selection range of processing, and the accuracy of the bonding position with the sensor chip are significantly improved, and the uniformity and reduction of the stress on the sensor chip are reduced. With this, it has the effect of obtaining high accuracy and high reliability.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a gas pressure detecting device according to the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a sectional view of a gas pressure detecting device of Embodiment 1, and FIG. 2 is a pressure sensor element 1 of Embodiment 1.
FIG. 3 shows the arrangement of the interval setting projections. In FIG. 1, the semiconductor pressure sensor element 1 has a thickness of 10 μm provided by etching on a silicon substrate.
And a semiconductor resistor whose resistance value changes due to mechanical strain caused by application of pressure is formed on the diaphragm film.

This pressure sensor element 1 is replaced with a gas-resistant adhesive 2
For setting the interval between the pressure introducing pipes 4 of the bottomed cylindrical sensor case 5 formed integrally with the lead frame 3 and the pressure introducing pipes (gas-resistant material) 4 via a (fluorine silicon adhesive) or the like. The gas pressure detecting passage 5 is formed so as to be supported on the convex portion 14 and to be kept airtight on the upper surface of the pressure introducing hole 12.

Electrically, the pressure sensor element 1 to the lead 8
~ Lead frame 3 ~ connected by circuit board 10,
The lead frame 3 also holds the circuit board 10.
The circuit board 10 has an electric circuit such as an amplifier circuit (not shown) formed thereon.

The resin case 6 houses the sensor case 5 and the circuit board 10 whose surfaces are coated with a potting agent 11, and has a pressure adjusting hole 1 in the upper part.
2 and a pressure chamber 13 formed in the pressure adjusting hole 12 by holding the sensor case 5 in an airtight state via an adhesive 9.

The gas-resistant rubber sealing material 7 is
And an O-ring configuration interposed in an airtight state between the outer wall surface of the resin case 6 and the inner wall surface of the pressure introducing portion of the resin case 6.

The operation of the above configuration will be described below. Due to the pressure difference between the pressure of the gas to be measured (LP gas, city gas) and the atmospheric pressure applied from the pressure introducing section 16 at the lower part of the resin case 6, the pressure sensor element 1 generates mechanical strain, The strain is proportional to the pressure difference between the applied pressure and the atmospheric pressure.

When the strain is generated in the pressure sensor element 1, the resistance value of the semiconductor resistor formed on the pressure sensor element 1 changes in proportion to the magnitude of the strain. Detecting this change in resistance,
By outputting an electric signal amplified by an amplifier circuit provided on the circuit board 10, the differential pressure between the applied pressure and the atmospheric pressure is measured.

When thermal stress or the like is applied, the stress of each component is transmitted to the pressure sensor element 1 via the gas-resistant adhesive 2 and the output changes. In this case, the stress transmission rate differs depending on the thickness and application position of the gas-resistant adhesive 2.

As the thickness increases, the stress is alleviated. Also,
The more uniform the thickness and applied state, the more the stress variation is reduced.

As described above, according to the present embodiment, the portion to be contacted by the gas to be measured (LP gas, city gas) is made of the gas-resistant rubber seal material 7 and the gas-resistant material. , City gas) can be prevented from material deterioration.

The applied thickness of the gas-resistant adhesive 2 is determined by the height of the interval setting projection 14 provided on the pressure introducing pipe 4, and is locally increased by making the thickness uniform over the entire circumference. An advantageous effect of reducing the stress can be obtained.

(Embodiment 2) FIG. 4 shows a cross section of a joint portion of a pressure sensor element 21 of Embodiment 2. In FIG. 4, a plurality of interval setting projections 24 are provided on the bonding surface of the pressure sensor element 21, and are joined with the gas-resistant adhesive 2 at these intervals.

The operation of the above configuration will be described below. The thickness and the adhesive bonding position of the gas-resistant adhesive 2 are determined by the interval setting projection 24 of the pressure sensor element 21. The gas-resistant adhesive 2 has a function of a cushioning material due to rubber elasticity. Stress due to thermal stress from other components is applied to the pressure sensor element 2 via the gas-resistant adhesive 2.
1 and the output changes. Therefore, the pressure sensor element 2
The non-uniformity of the adhesive thickness of the gas-resistant adhesive 2 on the lower surface of 1 and the bonding position to the pressure sensor element 21 are important factors of the output change.

As described above, according to this embodiment, the gas-resistant adhesive 2 is applied to the pressure sensor
The thickness of the adhesive and the bonding position become uniform by providing the pressure sensor element 21, and the pressure sensor element 21 and the interval setting projection 14 can be simultaneously processed, thereby improving the positional accuracy. As a result, the stress due to the thermal stress from other components to the pressure sensor element 21 is reduced and made uniform, and an advantageous effect that variation in output voltage and output change can be prevented can be obtained.

(Embodiment 3) FIG. 5 shows a cross-sectional structure of a joint portion of a pressure sensor element 1 according to a third embodiment. In FIG. It is fixed with the gas-resistant adhesive 2 with a gap provided between the projections 14. The support spacer 15 and the pressure introducing pipe 4 are joined by an appropriate joining method depending on the material of the support spacer 15 and the pressure introducing pipe 4 and the like.

The operation will be described below based on the above configuration. The influence of the stress on the pressure sensor element 1 is largely due to the material of the components, the joining method, the shape and material of the interval setting projection, and the like. Processing methods suitable for the characteristics are also important factors for achieving high accuracy and high reliability.

As described above, according to the present embodiment, high precision and high reliability can be realized by manufacturing the support spacer 15 by using the optimum material, the joining method, the interval setting convex shape 14, and the processing method. An advantageous effect is obtained.

[0033]

As described above, according to the present invention, it is possible to prevent the joint portion of the adhesive and the soft gel, which have been problems in the prior art, from deteriorating in the gas to be measured (LP gas, city gas). . That is, it is possible to reduce a change in absorptivity of stress of the pressure sensor element (diaphragm) generated by swelling and shrinking of the material. Therefore, a stable, highly accurate and highly reliable gas pressure detecting device can be realized in the gas to be measured (LP gas, city gas).

[Brief description of the drawings]

FIG. 1 is a sectional view of a gas pressure detecting device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a pressure sensor element junction of the device.

FIG. 3 is a diagram showing an arrangement of convex portions for setting a gap of the joint portion;

FIG. 4 is a sectional view of a joint of a gas pressure detecting device according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a joint of a gas pressure detecting device according to a third embodiment of the present invention.

FIG. 6 is a sectional view of a conventional pressure detecting device.

[Explanation of symbols]

 1, 21 pressure sensor element 2 gas-resistant adhesive 3 lead frame 4, 44 pressure introduction pipe (gas-resistant material) 5 sensor case 6 resin case (gas-resistant material) 7 gas-resistant rubber sealing material 8 lead 9 adhesive DESCRIPTION OF SYMBOLS 10 Circuit board 11 Potting agent (gel) 12 Pressure adjustment hole 13 Pressure chamber 14, 24 Protrusion for spacing setting 15 Support spacer 16 Pressure introduction part

Claims (3)

[Claims] 1. A pressure sensor element for outputting a pressure-receiving strain of a pressure-receiving film as an electric signal, and a gas detection passage, wherein a coating thickness of a gas-resistant adhesive on an outer peripheral surface of the pressure-receiving film of the pressure sensor element is constant. A pressure introducing pipe having an interval setting projection so as to have a thickness and supporting an outer periphery of the pressure sensor element, a lead frame for transmitting an electric signal from the pressure sensor element to a circuit board, and the pressure sensor element A circuit board for amplifying and transmitting the electric signal from the pressure sensor element based on the output / temperature characteristic data of the pressure sensor element, a pressure adjustment hole for opening a non-pressure receiving surface of a pressure receiving film of the pressure sensor element to the atmosphere, and a pressure adjustment hole. A gas pressure detecting device comprising: a gel-like filler for hermetically blocking a pressure-receiving surface and a non-pressure-receiving surface of the pressure sensor element; and a pressure chamber formed in a space on the non-pressure-receiving surface side via the filler. 2. The gas pressure detection device according to claim 1, wherein the interval setting projection is provided on the pressure sensor element. 3. The gas pressure detecting device according to claim 1, wherein a spacing setting convex portion is provided on the supporting spacer.