JP2011007533A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise while restraining the number of members, and to improve reliability in connection work with external connectors.SOLUTION: A pressure sensor 1 includes: a pressure sensor chip 2 (hereinafter, a chip 2) for detecting pressure of fluid, a package 4, a housing 5, a connector part 6, and a chip capacitor 9 for reducing noise. The package 4 houses the chip 2 and is penetrated by a pressure introduction hole 10. The housing 5 accommodates the package 4 and a through-hole 15 communicating with the pressure introduction hole 10 penetrates an inner bottom surface 5a. The connector part 6 includes: a connector terminal 18 extended from the package 4; and a fitting part 19 integrally formed with the housing 5. Terminals 9a, 9b are arranged at both the ends of the chip capacitor 9. The connector terminal 18 is fixed along the inner bottom surface 5a by caulking. The terminal 9a is surface-mounted to one of the plurality of connector terminals 18 and the terminal 9b is surface-mounted to another connector terminal 18.

Description

  The present invention relates to a pressure sensor for measuring the pressure of a fluid.

Conventionally, various pressure sensors for measuring the pressure of a fluid have been provided. An example of this type of pressure sensor is a pressure sensor 80 as shown in FIG. The pressure sensor 80
A pressure sensor chip 81 for detecting fluid pressure, a package 82, a housing 83, a printed wiring board 84, a circuit component 85, and a connector portion 86 are provided. The pressure sensor chip 81 is
It consists of a diaphragm formed into a thin film by processing a semiconductor substrate (silicon substrate) and a plurality of piezoresistive elements constituting a bridge circuit on the diaphragm. For example, when pressure is applied to the pressure sensor chip 81 by a fluid such as water, the diaphragm is bent and distortion occurs in the piezoresistive element. And the resistance value of a piezoresistive element changes with the said distortion, The pressure of the fluid is measured by taking out the detected value detected according to the change.

As shown in FIG. 6, the package 82 is formed in a box shape from a synthetic resin material and accommodates the pressure sensor chip 81 therein, and a pressure introducing hole 87 for introducing fluid pressure is formed in the lower wall portion thereof. It will be installed. The pressure introduction hole 87 is formed to pass straight through to the outside through the axial center of the introduction pipe 82a protruding downward in a cylindrical shape from the lower wall portion of the package 82.

As shown in FIG. 6, the housing 83 is formed by combining flat box-shaped first and second cases 83 a, 83 b that open on one side with each other and the opening surfaces of each other. Store in. A port portion 83c protruding downward in a cylindrical shape is disposed at the lower end portion of the first case 83a. The inner bottom surface 83 d of the housing 83 has a package 82.
A hole 83e into which the introduction pipe 82a is fitted is formed. On the inner bottom surface of the hole 83e, the introduction tube 8 is provided.
A through hole 88 communicating with the pressure introducing hole 87 of 2a is provided, and an O-ring formed in an annular shape from an elastic material on the inner peripheral surface of the hole 83e and having an inner diameter substantially equal to the outer diameter of the introducing pipe 82a. 89
Is inserted. Then, the introduction pipe 82a fitted into the hole 83e is inserted through the O-ring 89, whereby the gap between the package 82 and the housing 83 is sealed. The O-ring 89 is
The upward movement is restricted by a washer 90 disposed thereon.

As shown in FIG. 6, the printed wiring board 84 is fixed to the peripheral edge of the opening of the first case 83a, and detection values detected from the pressure sensor chip 81 are signaled on the upper and lower surfaces of the printed wiring board 84. A plurality of circuit components 85 for processing are mounted. Further, a recess 84 a into which the upper end of the package 82 is fitted is formed at the substantially central portion of the lower surface of the printed wiring board 84. The connector portion 86 can be connected to an external connector, and is connected to the printed wiring board 8 through a lead wire 91 led out from a lead-out hole 92 penetrating through the left end portion of the housing 83.
4 is electrically connected to the conductive pattern formed on the substrate 4.

Incidentally, the pressure sensor 80 is provided with the printed wiring board 84 on which a plurality of circuit components 85 are mounted as described above, whereas the pressure sensor described in Patent Document 1 is such a printed circuit board. There is no wiring board, and the chip has a two-chip configuration in which an integrated circuit chip for signal processing the detected value from the pressure sensor chip is mounted on the inner surface of the package on which the conductive pattern is formed. In addition, the connector portion of the pressure sensor is formed integrally with the housing so as to surround a plurality of connector terminals extending from the package and outputting detection values detected by the pressure sensor chip, and surrounding one end portion of the connector terminal. It is comprised from the fitting part fitted to a connector. Therefore, since the pressure sensor has a smaller number of members than the pressure sensor 80, the cost can be reduced.

JP 2000-337987 A

However, the pressure sensor described in Patent Document 1 has a problem that circuit components for reducing noise other than the above-described two chips cannot be easily mounted because the printed wiring board is not disposed. . On the other hand, there is also an idea that a chip capacitor for noise reduction is directly surface-mounted so as to straddle between connector terminals. However, an external force is applied to one end of the connector terminal each time the external connector is fitted to the fitting portion of the connector portion, and stress is applied to the joint portion between the connector terminal and the chip capacitor. There is a possibility that the joint portion is damaged by repeatedly performing the connecting operation.

The present invention has been made in view of the above-mentioned reasons, and the object thereof is to reduce noise while suppressing the number of members and to improve reliability during connection work with an external connector. It is to provide a pressure sensor that can be used.

In order to achieve the above object, a pressure sensor chip for detecting the pressure of a fluid and a pressure introduction hole for accommodating the pressure sensor chip and introducing the pressure of the fluid are provided. A box-shaped package, a box-shaped housing in which the package is housed and a through hole communicating with the pressure introduction hole is formed in the inner bottom surface; and an external connector connected to the pressure sensor chip And a noise reduction chip capacitor in which terminals are provided at both ends, respectively, and the connector part is electrically connected to the pressure sensor chip. A plurality of connector terminals extending from the package; and a fitting portion that is formed integrally with the housing so as to surround one end of the connector terminal and is fitted to the connector, The connector terminal is formed in the shape of an elongated strip, and is fixed by caulking along the inner bottom surface of the housing, and one of the terminals of the chip capacitor is one of the connectors The terminal is surface-mounted, and the other terminal of the chip capacitor is surface-mounted to the other connector terminal.

According to this invention, the connector terminal is formed in an elongated strip shape, and is caulked and fixed along the inner bottom surface of the housing, and the one terminal of the chip capacitor is
Since it is surface-mounted on any one of the plurality of connector terminals and the other terminal of the chip capacitor is surface-mounted on the other connector terminal, the chip can be provided without a printed wiring board. Capacitors can be easily mounted, and stress applied to the joint between the connector terminal and the chip capacitor during the connection work with the external connector, the connector terminal and the inner bottom surface of the housing It can be relaxed at the fixed part by caulking. Therefore, it is possible to reduce noise while suppressing the number of members, and it is possible to improve reliability at the time of connecting work with an external connector.

According to a second aspect of the present invention, in the first aspect of the invention, a groove portion into which the both end portions of the chip capacitor are respectively inserted is formed at a position where the terminal of the chip capacitor of the connector terminal is surface-mounted. It is characterized by that.

According to this invention, positioning of the chip capacitor to the connector terminal is facilitated and workability can be improved.

The invention of claim 3 is characterized in that, in the invention of claim 2, the groove is formed in a V-shape.

According to this invention, the corners of the both end portions of the chip capacitor can be fitted to face the groove portion, and positioning becomes easier. Furthermore, the area where the chip capacitor and the groove are joined by solder or an adhesive becomes wider than that formed by, for example, a U-shaped depression, and the joining strength can be improved.

In the present invention, it is possible to reduce noise while suppressing the number of members, and to improve the reliability at the time of connection work with an external connector.

It is sectional drawing of embodiment of this invention. It is a top view of the 1st case in the same as the above. The connector terminal in the same is shown, (a) is a top view, (b) is a sectional view. It is sectional drawing in which the groove part was formed in the connector terminal in the same as the above. (A) And (b) is sectional drawing in which the groove part in the same as the above was formed in V shape. It is sectional drawing of an example of the conventional pressure sensor.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the following description, the vertical and horizontal directions are defined in FIG. 1, and the front of FIG.

The pressure sensor 1 of this embodiment is for measuring the pressure of a fluid. As shown in FIG. 1, the pressure sensor chip 2, the integrated circuit chip 3, the package 4, the housing 5, and the connector portion 6 are used. , Oil 7, sealing material 8, and chip capacitor 9. And the pressure sensor 1 is attached to the flow path of the water (or warm water) in the water heater of a bathtub, for example,
The present invention can be applied to a water level sensor that detects the water level of a bathtub by the pressure in the flow path.

As described in the prior art, the pressure sensor chip 2 includes a diaphragm and a plurality of piezoresistive elements. As shown in FIG. 1, the silicon substrate is processed (etched) to form the recess 2a. The integrated circuit chip 3 processes the detection value detected from the pressure sensor chip 2. Further, since the resistance element of the pressure sensor chip 2 is easily influenced by the ambient temperature outside the pressure sensor 1 and there is a possibility that a change in resistance value due to the deflection of the diaphragm cannot be detected correctly, the integrated circuit chip 3 is The temperature of the detected value is also corrected by detecting the ambient temperature.

As shown in FIG. 1, the package 4 is formed in a box shape with one surface (upper surface in the figure) opened by a synthetic resin material, and an introduction tube 4a in which a pressure introduction hole 10 is provided in the lower wall portion. Is protruding. As shown in FIG. 1, the pressure sensor chip 2
Is fixed with the recess 2a facing downward, and the pressure introduction hole 10 of the introduction pipe 4a is disposed at a position facing the pressure sensor chip 2. The pressure introduction hole 10 and the recess 2a communicate with each other, and the hole 7 is filled with oil 7 for transmitting pressure from the fluid to the pressure sensor chip 2.
The oil 7 is non-corrosive, and even if the fluid is corrosive, the oil 7 is interposed between the fluid and the pressure sensor chip 2 to prevent the pressure sensor chip 2 from being corroded. be able to.

The above-described integrated circuit chip 3 is fixed to the vicinity of the right side where the pressure sensor chip 2 is disposed on the inner bottom surface of the package 4 as shown in FIG. The piezoresistive element of the pressure sensor chip 2, the integrated circuit chip 3, and the conductive patterns formed on the inner bottom surface of the package 4 are electrically connected through bonding wires 11, respectively, and three connector terminals 18 to be described later are electrically connected. Conducting with the pattern, the package 4 extends outward from the left side wall.

As shown in FIG. 1, the pressure sensor chip 2 and the integrated circuit chip 3 as described above are sealed by a sealing material 8 filled from the upper surface of the package 4, and further a rectangular plate so as to close the upper surface of the package 4. A shaped cover 12 is attached. The sealing material 8 is used to protect the chips 2 and 3 from oxidation. In this embodiment, the sealing material 8 has a high adhesion with a silicon substrate.
(Non Coating Resin) is filled as the sealing material 8.

As shown in FIG. 1, the housing 5 is formed by combining flat box-shaped first and second cases 13, 14 that open on one side with each other opening surfaces to each other. Store in. A port portion 13a that protrudes downward in a cylindrical shape at the lower end of the first case 13
Is disposed. As shown in FIG. 1, a step portion 5b is formed on the inner bottom surface 5a of the housing 5 so as to be recessed downward in substantially the same shape as the bottom portion of the package 4, and the introduction pipe of the package 4 is further formed on the bottom surface of the step portion 5b. A hole 5c into which 4a is inserted is formed. Further, as shown in FIGS. 1 and 2, four protruding portions 5 d are provided in a protruding manner in the vicinity of both left and right end portions of the inner bottom surface 5 a of the housing 5. A through hole 15 communicating with the pressure introducing hole 10 of the introduction pipe 4a is formed through the inner bottom surface of the hole 5c. The inner circumference of the hole 5c is formed in an annular shape from an elastic material and is formed in an annular shape of the introduction pipe 4a. An O-ring 16 and a washer 17 having an inner diameter substantially equal to the outer diameter are fitted. Then, the introduction pipe 4 a that fits into the hole 5 c is inserted through the O-ring 16, whereby the gap between the package 4 and the housing 5 is sealed.

As shown in FIGS. 1 and 2, the connector portion 6 includes three connector terminals 18 and a fitting portion 19 formed integrally with the left end portion of the housing 5 so as to surround one end portion 18 a of the connector terminal 18.
And is connectable to an external male connector (not shown). The connector 6 is connected to the connector and outputs a detection value detected by the pressure sensor chip 2 to the outside of the housing 5.

As shown in FIGS. 2 and 3A, each of the three connector terminals 18 is formed in a long strip shape, and in order from the front, the output voltage terminal Vout, the ground terminal GND, and the power supply voltage terminal VDD. It has become. Two noise reducing chip capacitors 9 are mounted on the surface so as to straddle between the connector terminals 18. That is, as shown in FIG. 3 (b), which is a cross-sectional view of FIG. 3 (a) taken along the dotted line position, the lower surfaces of the front and rear ends of the chip capacitors 9, 9 (both ends in the left / right direction in FIG. 3) Terminals 9a and 9b are respectively provided, and the chip capacitor 9
, 9 are joined to the output voltage terminal Vout and the rear end of the upper surface of the GND terminal by the solder 21, respectively, and the rear terminals 9b and 9b are similarly joined by the solder 21 to the GND terminal and the power supply voltage terminal VDD. Are joined to the front end portions of the top surfaces of the two. The chip capacitor 9 may be fixed with a conductive adhesive instead of the solder 21. The two chip capacitors 9 and 9 of this embodiment are mounted so as to straddle between adjacent connector terminals 18. For example, a chip capacitor 9 having a larger outer shape is used to It may be mounted on the front and rear connector terminals 18 so as to straddle the other connector terminals 18.

Further, as shown in FIG. 1, a hole 18 b is provided at a position facing the protruding portion 5 d of the housing 5 of the connector terminal 18. In addition to the connector terminals 18, the package 4 is formed in the shape of an elongated strip having the same shape as the connector terminals 18, and is further extended with a hole 20 a penetrating at a position facing the protrusion 5 d. One 20 is extended to the left wall and four to the right wall. Then, a total of eight protrusions 5 d are caulked and fixed in the opposing holes 18 b and 20 a, so that the connector terminal 18 and the extension piece 20 are fixed along the inner bottom surface 5 a of the housing 5. That is,
The package 4 is fixed to the housing 5 through the connector terminals 18 and the extension pieces 20.

When a fluid such as water flows into the through-hole 15 from the opening 13b on the lower surface of the port portion 13a, the diaphragm of the pressure sensor chip 2 is bent through the oil 7 and the piezoresistive element is distorted. Then, the resistance value of the piezoresistive element changes due to the strain, and the detection value detected in accordance with the change is taken out of the housing 5 through the connector portion 6, whereby the fluid pressure is measured.

Hereinafter, the operation of the pressure sensor 1 of the present embodiment will be described. Pressure sensor 1 of this embodiment
As described above, the connector terminal 18 is formed in the shape of an elongated strip, and is caulked and fixed along the inner bottom surface 5a of the housing 5. The front terminal 9a of the chip capacitor 9 is any one connector terminal. Since the rear terminal 9b is surface-mounted on the other connector terminal 18, the chip capacitor 9 can be easily mounted without a printed wiring board. Further, the stress applied to the joint portion between the connector terminal 18 and the chip capacitor 9 during connection work with an external connector is relieved by a fixing portion by caulking and fixing between the connector terminal 18 and the inner bottom surface 5a of the housing 5. Can do. Therefore, it is possible to reduce noise while suppressing the number of members, and it is possible to improve reliability at the time of connecting work with an external connector. 1 to 3, the fixing portion is disposed on the left side of the joint portion. However, the present invention is not limited to this, and the fixing portion may be disposed on the right side of the joint portion.

By the way, each terminal 9a, 9b of the above-mentioned chip capacitor 9 is directly joined to the upper surface of the adjacent connector terminal 18 by solder 21 as shown in FIG. 3 (b), but as shown in FIG. If the groove portions 22 into which the front and rear ends of the chip capacitor 9 are respectively inserted are formed at positions where the terminals 9a and 9b of the connector terminal 18 are surface-mounted, the positioning of the chip capacitor 9 to the connector terminal 18 is facilitated. Can be improved.

Further, as shown in FIGS. 5A and 5B, when the above-described groove portion 22 is formed in a V shape, the corners 9c of both ends in the front-rear direction of the chip capacitor 9 are fitted to face the groove portion 22. Can be positioned more easily. Furthermore, the area where the chip capacitor 9 and the groove portion 22 are bonded by the solder 21 or the adhesive is wider than that formed by being recessed in a U shape like the groove portion 22 in FIG. Can do. 4 and 5 (a) are shown in FIG. 3 (b).
5 is a cross-sectional view of the three connector terminals 18 cut in the front-rear direction, and FIG. 5B is a cross-sectional view of the single connector terminal 18 cut in the left-right direction.

DESCRIPTION OF SYMBOLS 1 Pressure sensor 2 Pressure sensor chip 4 Package 5 Housing 5a Inner bottom face 6 Connector part 9 Chip capacitor 9a Terminal 9b Terminal 10 Pressure introduction hole 15 Through-hole 18 Connector terminal 19 Fitting part

Claims (3)

A pressure sensor chip for detecting the pressure of the fluid; a box-type package in which the pressure sensor chip is housed and a pressure introduction hole for introducing the fluid pressure is provided; and the package is housed in the interior. A box-shaped housing having a through-hole communicating with the pressure introduction hole on the inner bottom surface; a connector portion that is connected to an external connector and outputs a detection value detected by the pressure sensor chip; and both end portions And a noise reduction chip capacitor in which each terminal is disposed,
The connector portion is formed integrally with the housing so as to surround a plurality of connector terminals electrically connected to the pressure sensor chip and extending from the package, and one end of the connector terminal. And a mating part
The connector terminal is formed in a long strip shape, and is fixed by caulking along the inner bottom surface of the housing, and one of the terminals of the chip capacitor is any one of a plurality.
The pressure sensor is surface-mounted on one of the connector terminals, and the other terminal of the chip capacitor is surface-mounted on the other connector terminal. The pressure sensor according to claim 1, wherein a groove portion into which the both end portions of the chip capacitor are respectively inserted is formed at a position where the terminal of the chip capacitor of the connector terminal is surface-mounted. The pressure sensor according to claim 2, wherein the groove is formed in a V shape.

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