JP2004264095A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensor for improving vibration-resistant performance by filling a gel-like member for suppressing vibration in a circuit board. <P>SOLUTION: The pressure sensor A converts pressure to an electric signal by a sensor element 4 arranged while receiving pressure in a medium to be measured introduced from a pressure introduction section 1a, and transmits the electric signal to the outside. The flexible circuit board 5 comprises a sensor connection section 5a electrically connected to the sensor element 4, a terminal section 5d for transmitting the electric signal to an external conduction path 6, and an arrangement section 5b for arranging an amplification circuit section 7 for amplifying at least an electric signal from the sensor element 4. Cases 1, 2 for accommodating at least the sensor elements 4, 5 and the circuit board, and a gel-like member 10 that is filled into at least one portion of the cases 1, 2 and suppresses the vibration of the circuit board 5 having flexibility are provided. Additionally, the pressure sensor A comprises a reinforcing board 5g arranged at the arrangement section 5b; and an elastic member 9 reaching a peripheral wall 1a in the case 1 from the outer periphery of the reinforcing board 5g. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pressure sensor that detects a pressure of a medium to be measured.
[0002]
[Prior art]
As a pressure sensor for detecting the pressure of a medium to be measured composed of a liquid, a gas, or the like, there is a pressure sensor disclosed in Patent Document 1, for example. In this pressure sensor, a semiconductor sensor element is disposed on a metal stem having a pressure introduction hole for introducing the pressure of a medium to be measured, via a metal base plate so as to face the pressure introduction hole. The sensor element is electrically connected to a printed board having a hole surrounding the sensor element by wire bonding. Various electronic components having at least an amplifier circuit for amplifying a signal detected by the sensor element are mounted on the printed board, and the amplified signal is transmitted from a lead pin provided on the printed board to a terminal. And output to the outside.
[0003]
The sensor element and the printed circuit board are housed in a cylindrical metal housing attached to the upper portion of the stem, and a resin terminal housing for guiding and supporting the terminal is provided at the upper portion of the housing. The housing and the terminal housing are closed by bending and crimping the entire upper end of the housing. Further, a screw portion is formed at a lower portion of the stem, and the pressure sensor is fixed by directly screwing the screw portion into a part of a measuring portion, for example, a vehicle engine.
[0004]
The above-described conventional electrical connection structure of a pressure sensor has a configuration in which a lead pin is provided on the printed circuit board, the lead pin and the terminal are electrically connected via solder or the like, and a signal from the sensor element is transmitted to the outside. Therefore, there is a problem that the electrical connection structure is complicated, and a pressure sensor that can easily perform the electrical connection has been desired. Therefore, the present applicant has proposed a pressure sensor disclosed in Patent Document 2. Such a pressure sensor has a connection portion electrically connected to the sensor element, an amplification circuit portion for at least amplifying an electric signal from the sensor element, and a terminal for transmitting the electric signal amplified by the amplification circuit portion to the outside. And a printed circuit board (circuit board) made of FPC (Flexible Printed Circuit), and the printed circuit board is accommodated in a housing made of a resin material in a state where the printed circuit board is bent at a predetermined position. And the terminal portion of the printed circuit board and the terminal portion of the printed circuit board are electrically connected using solder or the like. With this configuration, the pressure sensor can transmit the signal of the sensor element to the outside without providing the lead pin, thereby simplifying the electrical connection configuration, and simplifying the structure itself of the pressure sensor to reduce its size. Becomes possible.
[0005]
[Patent Document 1]
JP-A-3-237332 [Patent Document 2]
JP-A-2000-111432
[Problems to be solved by the invention]
However, such a pressure sensor that has a simplified structure and can be downsized is expected to be mounted on an outboard motor of a ship or a moving object (vehicle) having large vibration such as a vehicle (two-wheeled vehicle or four-wheeled vehicle). Rarely, a pressure sensor provided with an FPC is desired to have improved vibration resistance.
The present invention has been made in view of the above problems, and has as its object to provide a pressure sensor having high vibration resistance.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention converts the pressure into an electric signal by a sensor element disposed in a state of receiving a pressure of a medium to be measured introduced from a pressure introducing unit. A pressure sensor for transmitting the electric signal to the outside, a sensor connection part electrically connected to the sensor element, a terminal part for transmitting the electric signal to an external current path, An arrangement section for arranging an amplification circuit section for amplifying at least the electric signal, a circuit board having flexibility, a case body accommodating at least the sensor element and the circuit board, and at least one of the case bodies. And a gel member that is filled in the portion and suppresses vibration of the circuit board having flexibility.
[0008]
Further, according to the present invention, as described in claim 2, the pressure is converted into an electric signal by a sensor element arranged in a state of receiving the pressure of the medium to be measured introduced from the pressure introducing section, Pressure sensor that transmits the electrical signal to the outside, a sensor connection portion electrically connected to the sensor element, a terminal portion that transmits the electrical signal to an external conduction path, at least the electrical signal from the sensor element An arrangement section for disposing an amplification circuit section for amplification is provided, a circuit board having flexibility, a reinforcing plate disposed on the arrangement section, and at least the sensor element, the circuit board, and the reinforcing plate. And an elastic member provided so as to reach the peripheral wall of the case body from the outer periphery of the reinforcing plate.
[0009]
Further, according to the present invention, as described in claim 3, in the case body above the reinforcing plate, a storage space in which the circuit board is provided in a bent state is provided, and the storage space is provided in the storage space. A gel member for suppressing the vibration of the circuit is provided.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
1, a pressure sensor A includes a lower housing (case body) 1, an upper housing 2 (case body), a base plate 3, a sensor element 4, a circuit board 5, a cord (external current path) 6, It is mainly composed of
[0011]
The lower housing 1 is made of a heat-resistant and creep-resistant synthetic resin material, for example, polyphenylene sulfide (PPS), and is formed by insert-molding a pressure introducing portion 1a made of a metal material such as SUM. A screw portion 1b is formed in a lower portion of the lower housing 1, and the pressure sensor A is fixed to a measurement portion in, for example, a vehicle engine by the screw portion 1b. A pressure introducing hole 1c for introducing a medium to be measured, which is made of a liquid or a gas, is formed substantially at the center of the pressure introducing section 1a. In addition, the lower housing 1 includes a holder 1d that supports a reinforcing plate described later.
[0012]
The upper housing 2 is formed of a resin material such as PBT, and is disposed and fixed by heat-tightening the open end of the upper housing 2 to the open end of the lower housing 1. , The circuit board 5 and the like are stored. The upper housing 2 has a concave portion 2a formed at the upper portion, and the cord 6 is drawn out from the inside of the upper housing 2 toward the concave portion 2a. A grommet 2b is provided in the recess 2a, and an epoxy resin, for example, flows in from above the grommet 2b to fix and hold the cord 6, and to prevent dust and moisture from entering from the base of the cord 6.
[0013]
The base plate 3 is made of a metal material such as Kovar, and is formed in a substantially circular shape. Further, the base plate 3 has a flange portion 3a for being disposed and fixed to the upper end portion of the pressure introducing portion 1a in the lower housing 1 by resistance welding, and a base which is fitted to the pressure introducing portion 1a and is attached to the pressure introducing portion 1a. A protruding portion 3b for determining an arrangement position of the plate 3 is provided. A hole 3c for transmitting pressure to the sensor element 4 is provided substantially at the center of the flange 3a.
[0014]
In the sensor element 4, a semiconductor chip 4a having a diaphragm formed by thinning a semiconductor substrate such as silicon is disposed on a glass pedestal 4b, and the semiconductor chip 4a and the glass pedestal 4b are joined by an anodic bonding method. The diaphragm receives the pressure of the fluid introduced from the pressure introduction passage 4c provided in the glass pedestal 4b, and detects the displacement of the diaphragm. The sensor element 4 forms four pressure-sensitive elements having a piezoresistive effect by diffusing impurities such as boron into a portion corresponding to the diaphragm, and converts each of the resistors into a conductive material such as aluminum. A bridge circuit is formed by a wiring pattern using a material, and a pressure of the fluid is detected based on an output voltage of the bridge circuit accompanying displacement of the diaphragm. Further, the sensor element 4 forms a metallized layer on the back surface side of the glass pedestal 4b, and is connected to the base plate 3 via solder.
[0015]
The circuit board 5 is electrically connected to the sensor element 4 by wire bonding, and is formed by a flexible FPC. As shown in FIG. 2, the circuit board 5 made of the FPC includes a sensor connection portion 5 a that is wire-bonded to the sensor element 4, an amplifying function for amplifying an electric signal from the sensor element 4, an offset voltage of the sensor element 4, A first arranging portion 5b for arranging an amplifier circuit portion 7 composed of an IC package also having a temperature correction adjusting function of a full-scale voltage, a chip resistor for adjusting the magnitude of a current applied to the sensor element 4; A second arrangement part 5 c for disposing an electronic component 8 such as a capacitor for removing external noise is provided, and a terminal part 5 d for connecting to the cord 6.
[0016]
The circuit board 5 is provided between the sensor connection part 5a and the first disposition part 5b, between the first disposition part 5b and the second disposition part 5c, and between the second disposition part 5c and the second disposition part 5c. It is folded in a multilayer shape at a predetermined position between the terminal portion 5d and is housed in a space formed by the lower housing 1 and the upper housing 2 with the respective portions 5a to 5d facing each other.
[0017]
The sensor connection portion 5a includes a receiving plate 5e attached to the back surface of the circuit board 5 and reinforcing the circuit board 5 made of FPC, and a hole 5f communicating the circuit board 5 and the receiving plate 5e. With the circuit board 5 mounted on the base plate 4 together with 5e, wire bonding with the sensor element 4 can be performed through the hole 5f. In addition, the receiving plate 5e ensures the attachment to the lower housing 1.
[0018]
The first arranging part 5b is provided between the sensor connecting part 5a and the second arranging part 5c (between the sensor connecting part 5a and the terminal part 5d), and bends a predetermined portion of the circuit board 5. A reinforcing plate 5g is attached to one side of the non-opposite side of the sensor element 4, which is opposite to the sensor element 4, and an amplifier circuit section is provided on the other side. 7 is surface-mounted and is electrically connected to the amplifier circuit section 7 by soldering. The first arranging portion 5b is fixed on the lower housing 1 in a stable state by supporting the reinforcing plate 5g by a holder 1d attached to the lower housing 1.
[0019]
The second arranging portion 5c is provided between the first arranging portion 5b and the terminal portion 5d (between the sensor connecting portion 5a and the terminal portion 5d), and bends a predetermined portion of the circuit board 5 to form the second arranging portion 5c. It is disposed so as to be located above one disposition portion 5b, and removes chip resistance and external noise for adjusting a current value applied to the sensor element 4 from an external power supply (not shown) on both surfaces. Electronic component 8 including a capacitor and the like is provided. Further, the electronic component 8 is bonded to the reinforcing plate 5g via an adhesive so that a part of the electronic component 8 functions as a spacer member, so that the second disposing portion 5c is stably fixed. ing. The electronic component 8 may be provided only on one surface of the second mounting portion 5c. In addition, a dedicated spacer member may be provided on the second disposition portion 5c for fixing the second disposition portion 5c. In the embodiment of the present invention, a reinforcing plate 5g is provided on the first mounting portion 5b, a holder 1d for supporting the reinforcing plate 5g is provided, and a reinforcing plate 5g is provided on the second mounting portion 5c. Although the configuration is such that the spacer member is adhered to the second mounting portion 5c, a reinforcing plate is provided in the second mounting portion 5c, a holder for supporting the reinforcing plate is provided, and the first mounting portion is provided in the first mounting portion 5c. A configuration in which a spacer member adhered to the reinforcing plate may be provided.
[0020]
The terminal portion 5d is provided at an end of the circuit board 5, and is connected by soldering to a cord 6 for transmitting an electric signal detected by the sensor element 4 and adjusted and amplified by the amplifier circuit portion 7 to the outside. .
[0021]
A silicone rubber (elastic member) 9 is provided between the periphery of the reinforcing plate 5g and the peripheral wall 1a of the lower housing 1. That is, the area between the periphery of the reinforcing plate 5g and the peripheral wall 1a of the lower housing 1 is closed by the silicone rubber 9. Further, in order to suppress the vibration of the circuit board 5, a portion above the reinforcing plate 5g, that is, the terminal portion 5d side is filled with a silicone gel (gel member) 10. The silicone rubber 9 and the silicone gel 10 can provide a vibration suppressing structure for the circuit board 5 and the reinforcing plate 5g in the pressure sensor A. The silicone rubber 9 is applied to the outer periphery of the reinforcing plate 5g, and the silicone gel 10 Since it is possible to prevent the sensor element 4 from flowing into the pressure reference chamber in which the sensor element 4 is disposed, it is possible to perform good pressure detection by the sensor element 4.
[0022]
The cord 6 transmits the electric signal adjusted and amplified by the amplifier circuit section 7 to the outside through the terminal section 5d. The cord 6 is guided and supported from the recess 2a of the upper housing 2 via the grommet 2b. Is an external conduction path led to the outside. The external power supply path is not limited to a cord. For example, a configuration may be used in which a connector pin is projected from the upper housing and connection with the outside is made by a connector.
[0023]
The pressure sensor A includes a sensor connection part 5a electrically connected to the sensor element 4, a terminal part 5d for transmitting an electric signal to the cord 6, and an amplification circuit part 7 for amplifying the electric signal from the sensor element 4. A circuit board 5 composed of an FPC having an arrangement portion 5b to be arranged is accommodated in a case body composed of a lower housing 1 and an upper housing 2. Further, a reinforcing plate 5g is provided on the mounting portion 5b of the circuit board 5, and a silicone rubber 9 is provided so as to reach the peripheral wall 1a of the lower housing 1 from the outer periphery of the reinforcing plate 5g. With the above configuration, the vibration of the reinforcing plate 5g is suppressed by the vibration, and the electrical connection between the amplifier circuit portion 7 and the first disposing portion 5b, that is, the crack at the soldering portion of the amplifier circuit portion 7 due to the vibration is prevented. Is suppressed, the reliability of the electrical connection is improved, and a pressure sensor A having high vibration resistance can be obtained.
[0024]
Also, by filling a silicone gel 10 that suppresses vibration of the flexible circuit board 5 into a part of the case body, the circuit board 5 can be prevented from swinging due to the vibration. The connection point between the portion 5d and the cord 6 improves the reliability of the electrical connection in the same manner as the above-described portion, and the pressure sensor A with good vibration resistance can be obtained.
[0025]
【The invention's effect】
The present invention relates to a pressure sensor for detecting a pressure of a medium to be measured, and has improved vibration resistance.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a pressure sensor according to an embodiment of the present invention.
FIG. 2 is a diagram showing a circuit board of the pressure sensor according to the first embodiment;
[Explanation of symbols]
A pressure sensor 1 lower housing 2 upper housing 3 base plate 4 sensor element 5 circuit board 5a sensor connection part 5b first arrangement part 5c second arrangement part 5d terminal part 6 code (external conduction path)
7 Amplification circuit section 8 Electronic component 9 Silicone rubber (elastic member)
10 Silicone gel (gel member)

Claims (3)

A pressure sensor that converts the pressure into an electric signal by a sensor element disposed in a state of receiving the pressure of the medium to be measured introduced from the pressure introducing unit, and transmits the electric signal to the outside,
An arrangement in which a sensor connection electrically connected to the sensor element, a terminal for transmitting the electric signal to an external current path, and an amplifier circuit for amplifying at least the electric signal from the sensor are arranged. And a circuit board having flexibility,
A case body containing at least the sensor element and the circuit board;
And a gel member that is filled in at least a part of the case body and suppresses vibration of the circuit board having flexibility. A pressure sensor that converts the pressure into an electric signal by a sensor element disposed in a state of receiving the pressure of the medium to be measured introduced from the pressure introducing unit, and transmits the electric signal to the outside,
An arrangement in which a sensor connection electrically connected to the sensor element, a terminal for transmitting the electric signal to an external current path, and an amplifier circuit for amplifying at least the electric signal from the sensor are arranged. And a circuit board having flexibility,
A reinforcing plate disposed in the disposing portion,
A case housing at least the sensor element, the circuit board, and the reinforcing plate,
An elastic member provided so as to reach a peripheral wall of the case body from an outer periphery of the reinforcing plate. A storage space in which the circuit board is disposed in a bent state is provided in the case body above the reinforcing plate, and a gel member that suppresses vibration of the circuit is disposed in the storage space. The pressure sensor according to claim 2, wherein:

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