JPH0843224A - Pressure detecting device - Google Patents

Abstract

PURPOSE:To improve and stabilize the accuracy of a pressure sensor by making the atmosphere side of the sensor not fixed except a sensor case and resin case which are to be fixed. CONSTITUTION:A pressure detecting path is constituted by sticking a pressure sensor element 1 to the upper surface of the pressure introducing tube 4 of a sensor case 5. The sensor element 1 is electrically connected to leads 8, a lead frame 3, a circuit board 13, and terminals 12. In addition, such an electric circuit as the amplifier circuit, etc., is formed on the circuit board 10 and the surfaces of the sensor case 5 and board 10 are coated with a potting material 11 by housing the case 5 and board 10 in a resin case 6. Then, a resin case B14 is fixed to the resin case 6 after injecting the potting material 11. The sensor case 5 is not fixed to the resin case B14, but kept in a free state. Since the atmosphere side of a pressure detecting device is kept free, no unreasonable force is applied to the element 1 and the sensor element 1 becomes stable against such a thermal stress as the temperature change, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a pressure detecting device for detecting the gas pressure of LP gas / city gas.

[0002]

2. Description of the Related Art A conventional semiconductor pressure detecting device will be described. Generally, the conventional semiconductor pressure detecting device has a structure as shown in FIG. Semiconductor pressure sensor element 1
Is a diaphragm film having a thickness of several microns formed by etching on a silicon substrate, and a semiconductor resistor whose resistance value changes due to mechanical strain is formed on this film. A sensor case 5 formed by integrally molding the pressure sensor element 1 with the adhesive 2 and the lead frame 3 and the pressure introducing pipe 4 interposed therebetween.
It is held in an airtight state on the upper surface of the pressure introducing pipe 4 and constitutes a pressure detecting passage.

Electrically, the pressure sensor element 1, the lead 8, the lead frame 3, the circuit board 10, and the terminal 12 are electrically connected.
And the lead frame 3 is connected to the circuit board 10.
Is also held. Further, the circuit board 10 is formed with an electric circuit such as an amplifier circuit.

A resin case B 14 accommodates the sensor case 5 and the surface of the circuit board 10 coated with a potting material 11. Reference numeral 7 denotes a rubber seal material which is interposed in an airtight state between the outer wall surface of the pressure introducing pipe 4 and the inner wall surface of the pressure introducing portion of the resin case 6. The sensor case 5 is positioned on the resin case B14, and the adhesive B9
It is fixed at.

The operation of this pressure detecting device will be described below. The pressure sensor element 1 is mechanically distorted by the pressure difference between the pressure applied from the pressure introducing portion at the bottom of the resin case 6 and the atmosphere, and the mechanical strain is proportional to the pressure difference between the applied pressure and the atmospheric pressure. When the pressure sensor element 1 is distorted, a change in the resistance value of the semiconductor resistor formed on the pressure sensor element 1 is detected, amplified by an amplifier circuit provided on the circuit board 10, and output to apply. The pressure difference between the pressure and the atmospheric pressure is measured.

[0006]

However, in the above-mentioned structure, the pressure introducing pipe 4 on the pressure detecting side is fixed by the rubber seal material, and the sensor case 5 on the atmospheric pressure side is positioned on the resin case B14 and the adhesive B9. However, if the concentricity cannot be ensured due to the dimensional variation of the parts, there is a problem in that an unreasonable load is applied to the pressure sensor element 1 to cause distortion and change the original pressure.

Further, the sensor case 5 and the resin case B14
Even if the adhesive B9 used to fix the adhesive is defective in curing, it cannot be confirmed after assembly, and the potting material 11 penetrates into the upper portion of the pressure sensor element 1 to change the strain generated by the pressure. There was also the problem of letting it go.

[0008]

In order to solve the above problems, the present invention has a structure in which the fixing of the sensor case and the resin case B is removed, and the potting material can be filled from the atmospheric pressure side.

[0009]

The adhesive B can be eliminated by removing the fixing between the sensor case and the resin case B, and the pressure sensor element is not subjected to an unreasonable load because the atmospheric pressure side is free, so that the output of the pressure sensor is stable. In addition, the potting material can be filled from the atmospheric pressure side, and the filling amount can be managed while checking below the sensor case height, and it is possible to prevent the potting material from entering the pressure sensor element side and changing the strain. .

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The pressure detection device of this embodiment is shown in FIG. In addition,
Since the apparatus of this embodiment shown in FIG. 1 has basically the same configuration as the conventional apparatus shown in FIG. 2, the same components are designated by the same reference numerals and detailed description thereof will be omitted.

In the embodiment of FIG. 1, the pressure sensor element 1
Via the adhesive 2, the lead frame 3, the pressure introducing pipe 4
Is integrally molded, and is held in an airtight state on the upper surface of the pressure introduction pipe 4 of the sensor case 5 to form a pressure detection passage. Electrically, the pressure sensor element 1, the lead 8, the lead frame 3, the circuit board 10, and the terminal 12 are connected, and the lead frame 3 also holds the circuit board 10.

The circuit board 10 is formed with an electric circuit such as an amplifier circuit. A resin case 6 accommodates the sensor case 5 and the circuit board 10 whose surface is coated with a potting material 11. Reference numeral 7 denotes a rubber seal material which is interposed in an airtight state between the outer wall surface of the pressure introducing pipe 4 and the inner wall surface of the pressure introducing portion of the resin case 6. Also,
The sealing material 15 is interposed in an airtight state so that the potting material 11 does not enter the rubber sealing material 7. The resin case B14 is fixed by ultrasonic welding or the like after injecting the resin case 6 and the potting material 11, and has an air hole. The sensor case 5 is not fixed to the resin case B14 and is in a free state.

[0013]

As is apparent from the above description, in the pressure detecting device of the present invention, the adhesive B can be eliminated by removing the fixing between the sensor case and the resin case B, and the pressure can be reduced by freeing the atmospheric pressure side. Since an unreasonable load is not applied to the sensor element, it is possible to provide a pressure sensor that is stable against thermal stress such as temperature change.

Further, the structure is simple, the potting material can be filled from the atmospheric pressure side, and it is possible to manage the filling while checking the height below the sensor case height. Therefore, the potting material enters the upper part of the pressure sensor element. As a result, it is possible to provide a highly accurate pressure sensor without changing the generated strain.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of a pressure detection device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of a conventional pressure detecting device.

[Explanation of symbols]

 1 Pressure Sensor Element 2 Adhesive 4 Pressure Inlet Tube 5 Sensor Case 6 Resin Case 10 Circuit Board 11 Potting Material 14 Resin Case B

Claims (1)

[Claims] 1. A semiconductor pressure sensor element, a pressure introducing pipe which holds the pressure sensor element via an adhesive and constitutes a pressure detection passage surrounded in an airtight state with the surroundings, the pressure sensor element and a lead. A sensor case in which the lead frame electrically connected via
A resin case accommodating a circuit board electrically connected to the sensor case via the lead frame and an outer wall surface of the pressure introducing pipe and an inner wall surface of the pressure introducing portion of the resin case are hermetically sealed. A pressure detecting device comprising an intervening rubber seal material and filling a gel potting material around the circuit board inside the resin case.