JP2928748B2 - Pressure sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor for detecting pressure by a piezoresistance effect.

[0002]

2. Description of the Related Art Conventionally, there has been a pressure sensor as shown in FIGS.

A conventional pressure sensor will be described in detail with reference to FIGS. 19 and 20. The conventional pressure sensor includes an amplifier circuit (not shown) for amplifying a signal of a sensor chip 67 and a temperature compensation circuit (not shown). And a circuit board 53 provided with a variable resistor (hereinafter, referred to as a trimmer) 85 for setting a pressure value in order to obtain a digital signal such as ON / OFF according to an arbitrary pressure value, and detecting the pressure. It is configured by connecting the pressure detection board 55 to which the pressure sensor module 57 is attached with a flexible board 81 or a flat cable or the like (not shown). In the use state, the pressure detection board 55 to which the pressure sensor module 57 is attached as shown in FIG. 21 is arranged and stored in a case (not shown) so as to be substantially perpendicular to the circuit board 53. Have been. At this time, since the flexible board 81 is bent, the electrical connection between the pressure detection board 55 and the circuit board 53 is maintained even in such a state. Here, the pressure sensor module 57
This will be described in detail with reference to FIGS. 22 and 23. In the module housing 61, various terminals 63 are insert-molded, and a pressure inlet 59 is provided integrally. At the other end of the pressure inlet 59, the chip fixing portion 64 inside the module housing 61
Has a sensor chip 67 to which a glass pedestal 69 is joined.
Is fixed by an adhesive or the like, and is configured to receive the gas to be measured connected to the pressure inlet 59 on the pressure receiving surface 77 of the diaphragm 73 formed on the silicon chip 71. The pressure receiving surface 77 of the sensor chip 67
A pressure sensor element (not shown) is formed on the opposite side of the diaphragm 73. When the pressure of the gas to be measured causes the diaphragm 73 to bend and the pressure sensor element to be distorted, the pressure is increased in accordance with the applied pressure. Since the resistance value of the sensor element changes, the pressure to be measured can be detected using the change in the resistance value. A signal of the sensor chip 67 is supplied to a chip electrode 75 formed on the sensor chip 67,
By electrically bonding the terminal electrode 76 of the terminal 63 insert-molded to the module housing 61 to the sensor chip 67 and the various terminals 63, electrical connection is made. Further, after the wire bonding is performed, the sensor chip 67 and the terminal electrode 7 are connected.
The pressure sensor module 57 is configured by performing processing such as potting as necessary on 6 and the like, and mounting the module cover 65 on the bottom of the module housing 61.

[0004]

However, the conventional pressure sensor has the following disadvantages.

A sensor chip 67 for detecting pressure is housed in a pressure sensor module 57,
Since the temperature compensation circuit (not shown) provided for performing the temperature compensation of 7 is formed on the circuit board 53, the operating temperature of the sensor chip 67 differs from that of the circuit board 53, and the temperature of the circuit board 53 is different. The temperature compensation circuit (not shown) formed in the above does not function properly, and the reliability is reduced. Further, since the pressure sensor module 57 must be separately assembled as well as the assembly of the pressure sensor 51, the number of manufacturing steps and the number of parts are increased, resulting in a large number of defective assemblies.

To obtain a digital output according to an arbitrary set pressure, it is necessary to provide a variable resistor (trimmer) 85 for setting a pressure value on the circuit board 53. Pressure detection board 55
And the circuit board 53 to which the trimmer 85 is attached are separately formed via the flexible board 81. Therefore, when the pressure sensor 51 is housed in a case or the like (not shown), the pressure sensor module 57 A pressure inlet 59,
The relative position with respect to the trimmer 85 attached to the circuit board 53 is not fixed, so that the storing operation is difficult and the miniaturization is difficult. Further, during the storage operation or the like, an excessive force acts on the connection portion (A) 83 and the connection portion (B) 84 between the flexible substrate 81 and the pressure detection substrate 55 and the circuit board 53, and the connection portion (A) 83, The electrical connection and the mechanical connection of the connection portion (B) 84 are liable to cause troubles, resulting in poor durability and difficulty in automation of assembly.

The present invention has been made in view of the above-mentioned conventional drawbacks,
An object of the present invention is to provide a small, lightweight, highly reliable and durable pressure sensor that has high mechanical strength, has a small number of parts, simplifies the manufacturing process, is easy to automate, and has a high degree of reliability.

[0008]

In order to achieve the above object, the present invention relates to a pressure sensor for detecting pressure by a piezoresistive effect, which has a hole or a notch, and is provided around the hole or the notch. A circuit board having a plurality of positioning holes, and a chip fixing portion at a position corresponding to the hole or the notch, and a sensor chip is fixed to the chip fixing portion and corresponds to a positioning hole of the circuit board. It has a positioning pin at a location, and includes a pressure introduction port having a pressure introduction port in a direction substantially perpendicular to the positioning pin,
The pressure introducing port is fixed to the circuit board in a state where the positioning pin of the pressure introducing port is inserted into the positioning hole of the circuit board from below, and formed on the electrode formed on the sensor chip and the circuit board. The thus formed electrodes are electrically connected by wire bonding to form a pressure sensor. Further, in a pressure sensor for detecting pressure by a piezoresistance effect, a circuit board having a hole or a notch, and having a plurality of positioning holes around the hole or the notch, and a pressure sensor corresponding to the hole or the notch. And a sensor chip is fixed to the chip fixing portion, and a positioning pin is provided at a position corresponding to a positioning hole of the circuit board, and pressure is introduced in a direction substantially perpendicular to the positioning pin. A pressure introducing port having an opening, and a chip cover having an outwardly protruding locking piece engaged with a portion corresponding to the hole or the notch, wherein a positioning pin of the pressure introducing port is used for positioning the circuit board. The pressure introduction port is fixed to the circuit board in a state of being inserted into the hole from the lower side, and is formed on the electrode formed on the sensor chip and the circuit board. And the chip cover is electrically connected by wire bonding, and the locking piece of the chip cover is inserted from above the hole or cutout of the circuit board, and the connection between the lower surface of the circuit board and the chip cover is made. The tip cover is held by the engagement with the stop piece to constitute a pressure sensor. Further, in a pressure sensor for detecting pressure by a piezoresistive effect, a circuit board having a hole or a notch, and a zero point adjustment circuit or a span adjustment circuit and a temperature compensation circuit of a sensor chip provided on the circuit board; A large number of electric circuits are formed on a substrate, and a circuit selection means for variously selecting the electric circuit is provided by laser-cutting a circuit selection pattern formed on the circuit substrate according to an application. A chip fixing portion at a portion corresponding to a portion or a notch portion, a sensor chip fixed to the chip fixing portion, a pressure introduction port fixed to the circuit board, an electrode formed on the sensor chip, and the circuit. An electrode formed on a substrate is electrically connected by wire bonding to cover the sensor chip and block external light. Is provided in a hole or a notch of the circuit board, and the pressure sensor is configured by fixing the circuit board and the pressure introduction port by caulking and welding a positioning pin provided in the pressure introduction port. I have.

[0009]

In the pressure sensor configured as described above, the pressure introduction port and the sensor chip are integrally formed on the circuit board, so that the number of parts can be reduced and the mechanical strength can be improved. The operating environment temperatures of the sensor chip and the temperature compensation circuit become the same, so that appropriate temperature compensation can be performed, and the reliability of the pressure sensor improves. In addition, even when a variable resistor (trimmer) for setting a pressure value is provided to obtain a digital signal for an arbitrary set pressure, the relative position between the pressure introduction port and the trimmer is stabilized. Can be simplified, and automation can be facilitated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments of the invention shown in the drawings.

In the first embodiment of the present invention shown in FIGS. 1 and 2, 1a is a pressure sensor of the present invention, and 3a is a hole 5
a and a positioning hole 7, and a circuit board on which an amplifying circuit (not shown) and a temperature compensating circuit (not shown) composed of circuit components (not shown) such as various chip resistors are formed. From below the positioning hole 7 of the circuit board 3a,
The positioning pin 15 formed in the pressure introducing port 11 is inserted, and the circuit board 3a and the pressure introducing port 17 are arranged substantially at the center lower portion of the hole 5a of the circuit board 3a. The port 11 is fixed by a method such as bonding. The fixing of the circuit board 3a and the pressure introducing port 11 may be performed by caulking and welding the positioning pins 15 without using a method such as bonding. A sensor chip 67 is fixed on the chip fixing portion 17 of the pressure introduction port 11 with an epoxy adhesive or the like, and a chip electrode 75 formed on the sensor chip 67 is formed.
And the substrate electrode 9 formed on the circuit board 3a are electrically connected by wire bonding. Although the sensor chip 67 to which the glass pedestal 69 is joined is used in FIG. 2, the sensor chip 67 is not limited to this, and the sensor chip 67 and the chip electrode 7 may be used.
5, a process such as potting may be performed on the substrate electrode 9 or the like.

In the pressure sensor 1a having the above structure, since the circuit board 3a, the pressure introduction port 11, and the sensor chip 67 are formed integrally, the mechanical strength is increased, the durability is excellent, and the number of parts is reduced. Simplification of the manufacturing process can be achieved. In addition, this makes it easy to automate the assembly and can reduce the cost.

Since the sensor chip 67 and the circuit board 3a on which the temperature compensation circuit is formed are disposed in substantially the same portion, the operating environment temperature becomes the same, and highly accurate temperature compensation can be performed. A pressure sensor having high performance can be obtained.

[0014]

Next, different embodiments of the present invention shown in FIGS. 3 to 18 will be described. In addition,
In describing these different embodiments of the present invention,
The same components as those of the first embodiment of the present invention are denoted by the same reference numerals, and redundant description will be omitted.

The second embodiment of the present invention shown in FIGS. 3 and 4 mainly differs from the first embodiment of the present invention in that a notch portion is provided instead of the hole 5a of the circuit board 3a. 5b
Has been formed.

In FIG. 3, reference numeral 3b denotes a circuit board composed of a printed circuit board (hereinafter referred to as a PCB), in which an amplifier circuit and a temperature compensation circuit are formed, as in the first embodiment of the present invention. A notch 5b and a positioning hole 7 are provided. A positioning pin 15 formed in the pressure introduction port 11 is positioned below the positioning hole 7 of the circuit board 3b.
Is inserted, and the tip of the positioning pin 15 of the pressure introduction port 11 is caulked and welded in a state where the chip fixing portion 17 of the pressure introduction port 11 is arranged substantially below the center of the cutout 5b of the circuit board 3b. The circuit board 3b and the pressure introduction port 11 are fixed. The circuit board 3b
As in the first embodiment of the present invention, a method such as adhesion can be used for fixing the pressure introduction port 11 to the pressure introduction port 11.

The third embodiment of the present invention shown in FIGS. 5 to 18 differs from the first embodiment of the present invention mainly in that a zero point adjusting circuit (not shown) is provided on the circuit board 3a. ), A span adjusting circuit (not shown) is formed, a plurality of electric circuits (not shown) are formed, and a circuit selecting means for variously selecting the electric circuit according to the application is provided. That is, the chip cover 31 is mounted on the circuit board 3a.

In FIG. 5, reference numeral 3a denotes a circuit board made of a PCB. The pressure introducing port 11 is positioned by the positioning hole 7 and the positioning pin 15 similarly to the first embodiment of the present invention. Is fixed by caulking and welding. Similarly to the first embodiment of the present invention, after the sensor chip 67 is fixed at a predetermined position and potting or the like is performed on the sensor chip 67, the chip electrode 75, the substrate electrode 9, and the like, if necessary. The chip cover 31 covers the circuit board 3 so as to cover the sensor chip 67.
a. Reference numeral 85 denotes a variable resistor (trimmer) for setting an arbitrary pressure value when the pressure sensor of the present invention is operated as a pressure switch, and is connected to a predetermined circuit provided on the circuit board 3a. This trimmer 85
It can be unnecessary. Here, the mounting of the chip cover 31 will be described in detail with reference to FIGS. 10 to 13. The guide portion 35 of the chip cover 31 is inserted into the chip cover insertion portion 8 of the hole 5a, and is pressed as it is. The locking piece 33 engages with the chip cover locking portion 6 located in the hole 5a on the lower surface of the circuit board 3a, and the chip cover 31 is mounted and held on the circuit board 3a. At this time, the guide portion 35 and the like of the chip cover 31 are connected to the circuit board 3a.
As shown in FIGS. 14 and 15, a predetermined position of the pressure introduction port 11 is
9 or a concave portion (not shown) is formed. FIG.
FIG. 4 is a diagram for explaining trimming (resistance adjustment) of the trimming chip resistor 23 constituting the zero point adjustment circuit and the span adjustment circuit (not shown). The trimming chip resistor 23 formed on the base 27 is , (X1, Y1) to (X
1 ′, Y1 ′), (X2, Y2) to (X2 ′, Y
2 '), laser cuts from (X3, Y3) to (X3', Y3 ') are performed to obtain a desired resistance value and perform zero point adjustment and span adjustment. FIG. 17 is a front view thereof. FIG. 18 is a view for explaining a circuit selection pattern 29 (circuit selection means) for variously selecting a plurality of formed electric circuits (not shown) according to the purpose of use.
The circuit selection pattern 29 formed on the circuit board 3a as shown in FIG.
Various electric circuits are selected by making the patterns shown in FIG. Although the third embodiment of the present invention employs a laser cutting method for the circuit selecting means, various other methods such as forming the circuit selecting means by a rotary switch may be used. Can be.

Since the zero point adjustment circuit and the span adjustment circuit are formed on the circuit board 3a, the number of components can be reduced and the size can be reduced. In addition, by providing a plurality of electric circuits and circuit selection means on the circuit board 3a, it can be used for various purposes and cost can be reduced.

Since the chip cover 31 is mounted on the circuit board 3a so as to cover the sensor chip 67, the sensor chip 67 is irradiated with light even when the pressure sensor 1c is not housed in a case (not shown) or the like. And a stable sensor output can be obtained. Further, since it is possible to prevent foreign substances from adhering to the sensor chip 67, a pressure sensor having excellent reliability and durability can be obtained.

When the trimmer 85 is provided on the circuit board 3a, the pressure introducing port 13 of the pressure introducing port 11 and the trimmer 85
Since the relative position with respect to the position becomes accurate, the storing operation in a case or the like becomes easy and automation becomes easy.

[0022]

As apparent from the above description, the following effects can be obtained in the present invention.

(1) A pressure sensor for detecting pressure by a piezoresistance effect has a hole or a notch,
A circuit board having a plurality of positioning holes around the hole or the notch, and a chip fixing portion at a position corresponding to the hole or the notch, and a sensor chip fixed to the chip fixing portion; A positioning pin is provided at a position corresponding to the positioning hole of the circuit board, and a pressure introducing port having a pressure introducing port in a direction substantially perpendicular to the positioning pin is provided, and the positioning pin of the pressure introducing port is provided on the circuit board. The pressure introduction port is fixed to the circuit board while being inserted into the positioning hole from below, and the electrode formed on the sensor chip and the electrode formed on the circuit board are electrically connected by wire bonding. Since the pressure sensor is configured by this, the mechanical strength is improved as compared with a conventional circuit board and a pressure detection board having a different configuration, Durability is improved. In addition, the automation of assembly becomes easy to measure. Furthermore, since a pressure sensor module is not separately required, the number of components can be reduced, and the manufacturing process can be simplified. In addition, manufacturing defects can be reduced, and costs can be reduced. (2) In a pressure sensor for detecting pressure by a piezoresistance effect, a circuit board having a hole or a notch, and having a plurality of positioning holes around the hole or the notch; A chip fixing portion is provided at a corresponding position, a sensor chip is fixed to the chip fixing portion, and a positioning pin is provided at a position corresponding to a positioning hole of the circuit board, and pressure is applied in a direction substantially perpendicular to the positioning pin. A pressure introduction port having an introduction port, a chip cover having an outwardly protruding locking piece that engages with a portion corresponding to the hole or the notch, and a positioning pin of the pressure introduction port is provided on the circuit board. The pressure introducing port is fixed to the circuit board while being inserted into the positioning hole from below, and is formed on the electrode formed on the sensor chip and the circuit board. And the chip cover is electrically connected by wire bonding, and the locking piece of the chip cover is inserted from above the hole or cutout of the circuit board, and the connection between the lower surface of the circuit board and the chip cover is made. Since the tip cover is held by the engagement of the stopper and the tip cover, the pressure sensor is constituted.
In addition to the effects described above, the characteristics of the pressure sensor do not change due to the influence of light, and the adhesion of foreign substances to the sensor chip can be prevented, so that the reliability can be improved.
In addition, since there is no need for a separate case to block light,
Since the cost can be reduced and a transparent (light-transmitting) case can be used, it is possible to construct a playful product that is free from a black box-like element. (3) In a pressure sensor for detecting pressure by a piezoresistance effect, a circuit board having a hole or a notch;
A circuit selection pattern formed on the circuit board, provided with a zero point adjustment circuit or a span adjustment circuit and a temperature compensation circuit for a sensor chip, and a large number of electric circuits formed on the circuit board depending on the application. Circuit cutting means for variously selecting the electric circuit by laser cutting, a chip fixing portion at a position corresponding to a hole or a cutout of the circuit board, and a sensor chip fixed to the chip fixing portion. A pressure introducing port fixed to the circuit board, an electrode formed on the sensor chip and an electrode formed on the circuit board are electrically connected by wire bonding, and the sensor chip is covered with external light. A chip cover for shutting off the pressure is provided in a hole or a notch of the circuit board, and when the circuit board is fixed to the pressure introduction port, the pressure introduction port is fixed. Since the pressure sensor is constructed by being made by caulking welding of positioning pins provided on the bets, it is possible to reduce the number of parts, can be miniaturized. Further, the operating temperature environments of the sensor chip and the temperature compensating circuit are substantially the same, and optimal temperature compensation can be performed, so that reliability can be improved. Further, one pressure sensor can be used for various purposes, mass production is possible, and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a plan view showing a second embodiment of the present invention.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a plan view showing a third embodiment of the present invention.

FIG. 6 is a front view showing a third embodiment of the present invention.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 5;

FIG. 8 is a plan view showing a circuit board according to the first embodiment of the present invention.

FIG. 9 is a sectional view taken along line IX-IX of FIG. 8;

FIG. 10 is a sectional view taken along line XX of FIG. 8;

FIG. 11 is a plan view showing a chip cover according to a third embodiment of the present invention.

FIG. 12 is a front view showing a chip cover according to a third embodiment of the present invention.

FIG. 13 is a side view showing a chip cover according to a third embodiment of the present invention.

FIG. 14 is a plan view showing a pressure introduction port according to the first embodiment of the present invention.

FIG. 15 is a bottom view showing the pressure introduction port according to the first embodiment of the present invention.

FIG. 16 is a plan view showing a trimming chip resistor according to a third embodiment of the present invention.

FIG. 17 is a front view showing a chip resistor for trimming according to a third embodiment of the present invention.

FIG. 18 is an explanatory diagram showing a circuit selection pattern according to the third embodiment of the present invention.

FIG. 19 is a plan view showing a conventional pressure sensor.

FIG. 20 is a front view showing a conventional pressure sensor.

FIG. 21 is a front view showing a state in which a conventional pressure sensor is assembled.

FIG. 22 is a cross-sectional view showing a pressure sensor module of a conventional pressure sensor.

FIG. 23 is a bottom view showing a pressure sensor module viewed through a module cover of a conventional pressure sensor.

[Explanation of symbols]

1a, 1b, 1c: pressure sensor, 3a, 3b: circuit board, 5a: hole, 5b: notch, 6: chip cover locking part, 7: positioning hole, 8: chip cover insertion part, 9: substrate electrode, 11 : Pressure introduction port, 13: pressure introduction port, 15: positioning pin, 17: chip fixing part, 19: locking groove, 21: fixing groove, 23: chip resistance for trimming, 25: pattern cut part, 27: base 29: circuit selection pattern, 31: chip cover, 33: locking piece, 35: guide, 36: notch, 51: pressure sensor, 53: circuit board, 55: pressure detection board, 57: pressure sensor module, 59 : Pressure inlet, 61: module housing, 63: terminal, 64: chip fixing part, 65: module cover, 67: sensor chip, 69: glass pedestal, 71: silicon Chip, 73: diaphragm, 75: chip electrode, 76: terminal electrode, 77: pressure receiving surface, 79: wire, 81: flexible substrate, 83: connection part (A), 84: connection part (B), 85: variable resistance Vessel (trimmer).

Claims (3)

(57) [Claims] 1. Pressure is detected by a piezoresistance effect.
The pressure sensor has a hole or notchAround the hole or notch
Multiple positioning holes on the sideA circuit board, and a chip fixing portion corresponding to the hole or the notch.
A sensor chip is fixed to the chip fixing portion.And
Together, The circuit boardPosition corresponding to the positioning hole of
It has a positioning pin, and it is
Has a pressure inletPressure introduction port andEquipped,The positioning pin of the pressure introduction port is located in front of the circuit board.
With the pressure guide inserted into the positioning hole from the bottom,
An input port is fixed to the circuit board;  The electrodes formed on the sensor chip and the circuit board
The electrode formed is electrically connected by wire bonding.
ContinuedWasPressure sensor characterized by the above-mentioned. 2. Pressure is detected by a piezoresistance effect.
The pressure sensor has a hole or notchAround the hole or notch
Multiple positioning holes on the sideCircuit board,Said Tip fixing part at the place corresponding to the hole or notch
A sensor chip is fixed to the chip fixing portion.And
Together, The circuit boardPosition corresponding to the positioning hole of
It has a positioning pin, and it is
Has a pressure inletPressure introduction port,Outside engaging with the hole or notch
And a chip cover having a locking piece protruding into The positioning pin of the pressure introduction port is located in front of the circuit board.
With the pressure guide inserted into the positioning hole from the bottom,
An input port is fixed to the circuit board;  The electrodes formed on the sensor chip and the circuit board
The electrode formed is electrically connected by wire bonding.
ContinuedTogether with,Said Chip hippoThe locking piece isHoles or cuts in the circuit board
Missing partFrom the upper side of the circuit board, and the lower side of the circuit board and the
When the chip cover is engaged with the locking piece, the chip
Hippo was retainedPressure sensor characterized by the above-mentioned. 3. A pressure sensor for detecting pressure by a piezoresistance effect, comprising: a circuit board having a hole or a notch; a zero point adjustment circuit or a span adjustment circuit and a temperature compensation circuit for a sensor chip provided on the circuit board. And a circuit selecting means for selecting various electric circuits by laser cutting a circuit selection pattern formed on the circuit board according to the application, in which a large number of electric circuits are formed on the circuit board; A pressure fixing port having a chip fixing portion at a portion corresponding to a hole or a cutout portion of the substrate, a sensor chip fixed to the chip fixing portion, and a pressure introduction port fixed to the circuit board; and an electrode formed on the sensor chip. And the electrodes formed on the circuit board are electrically connected by wire bonding to cover the sensor chip and block external light. A cover is provided in a hole or a cutout of the circuit board, and the fixing between the circuit board and the pressure introduction port is performed by caulking and welding a positioning pin provided in the pressure introduction port. Features pressure sensor.