JP2016188775A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent charging in a pressure-receiving space of a pressure sensor in a semiconductor pressure detector, the detector including: a diaphragm receiving the pressure of a fluid; a base having a pressure-receiving space containing a sealed insulating medium such as oil, the space being located between the base and the diaphragm; and a plurality of bonding pads in the pressure-receiving space having an earth pad.SOLUTION: A static eliminating plate 100 is arranged on a base 40 at a higher level than a semiconductor pressure detector 60, and is electrically connected to an earth pad and an earth terminal pin 72 of the semiconductor pressure detector 60.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure sensor, and more particularly, to a liquid-filled pressure sensor containing a semiconductor-type pressure detection device.

Conventionally, a liquid-filled pressure sensor that contains a semiconductor-type pressure detection device in a pressure-receiving chamber that is partitioned by a diaphragm and sealed with oil is installed in a freezer / refrigerator or an air conditioner to detect refrigerant pressure, It is installed in equipment and used to detect various fluid pressures.
The semiconductor-type pressure detection device is disposed in the pressure receiving chamber and has a function of converting a pressure change in the pressure receiving space into an electric signal and outputting the electric signal to the outside.
The diaphragm placed in the pressure-receiving space is made of a flexible metal plate, so that depending on the environment in which it is used, a potential difference may occur between the pressure sensing element made of semiconductor and the metal housing, or it may be sealed If the oil is charged with static electricity, charges may accumulate on the surface of the pressure detection element, which may cause a malfunction in the detection operation of the pressure detection element.

  Therefore, a pressure sensor that solves the above-described problem by further disposing a conductive member in the pressure receiving space in which the pressure detecting element is accommodated and connecting the conductive member to the zero potential of the electric circuit is as follows. It is disclosed in Patent Document 1.

Japanese Patent Laying-Open No. 2015-4591

However, in the pressure sensor disclosed in Patent Document 1, when the pressure detection element and the conductive member are charged with the upper member (base) forming the pressure receiving space, the pressure detection element is at a distance from the diaphragm. In this arrangement, the opposing surfaces are closer than the conductive member (the distance between them is narrow).
For this reason, the amount of charge charged between the pressure detection element and the diaphragm may be larger than the amount of charge charged between the conductive member and the diaphragm. There is concern that it will not play its role.

  Therefore, an object of the present invention is to concentrate the charge on the conductive member rather than the pressure detecting element when the conductive member is arranged in the pressure receiving space, and charge the external potential from the zero potential of the electric circuit of the pressure detecting element. It is to provide a pressure sensor that can release the pressure.

  In order to achieve the above object, a pressure sensor according to the present invention includes a diaphragm that receives a pressure of a fluid, a base in which a pressure receiving space in which an insulating medium such as oil is enclosed is formed between the diaphragm, A semiconductor-type pressure detection device provided in the pressure-receiving space and provided with a plurality of bonding pads including a ground pad; a plurality of terminal pins implanted in the base and electrically connected to the semiconductor-type pressure detection device; A pressure sensor including a single ground terminal pin connected to a zero potential of a semiconductor type pressure detection device, wherein a neutralization plate is provided on the base at a peripheral position of the semiconductor type pressure detection device; The neutralization plate is disposed so that a height from the base is higher than a height from the base of the semiconductor pressure detector, Plate, characterized in that the connected ground pad and the ground terminal pin and electrically the semiconductor-type pressure sensing device.

In the pressure sensor of the present invention, the charge removal plate is electrically connected to the ground terminal pin by soldering.
Furthermore, in the pressure sensor of the present invention, the charge removal plate may be configured to provide a charge removal plate in a part of the peripheral position of the semiconductor pressure detection device.

  According to the pressure sensor of the present invention, charges can be concentrated on the conductive member (static discharge plate) rather than the pressure detection element, and therefore, a pressure sensor excellent in resistance to static electricity and the like and reliability can be provided.

It is a longitudinal cross-sectional view of the pressure sensor by this invention. It is the schematic which looked at the vicinity of the part which attached the semiconductor type pressure detection apparatus of the pressure sensor by this invention from the pressure receiving space side, and is AA sectional drawing of FIG. FIG. 3 is an enlarged view of a main part showing the positional relationship between the semiconductor pressure detector and the charge removal plate in the longitudinal sectional view shown in FIG. 1, and is an enlarged view of a portion B in FIG.

FIG. 1 is a longitudinal sectional view of a pressure sensor according to the present invention. FIG. 2 is a schematic view of the vicinity of the portion where the semiconductor type pressure detecting device of the pressure sensor according to the present invention is attached as viewed from the pressure receiving space side.
As shown in FIG. 1, the pressure sensor 1 includes a stepped cylindrical cover 10, and a base 40 on which a semiconductor-type pressure detection device 60 described later is mounted in a large-diameter opening 10 a of the cover 10. A pressure detection unit 2 including a mounting member 30 that supports a connection nut 20 to which a fluid inflow pipe (not shown) is connected, a base 40, a diaphragm 50 having an outer peripheral portion sandwiched between the mounting members 30, and the like is inserted.

The pressure receiving space 52 defined by the dish-shaped base 40 and the diaphragm 50 is filled with an insulating liquid medium such as oil. The ball 99 is for sealing the hole after filling the pressure receiving space 52 with a liquid medium through a hole (not shown) formed in the base 40, and the base 40 is sealed by means such as welding. It is fixed.
A semiconductor-type pressure detection device 60 is mounted at the center of the base 40 on the pressure receiving space 52 side. The semiconductor-type pressure detection device 60 includes a glass pedestal 62 and a pressure detection element (semiconductor chip) 64 attached thereto. The pressure detection element 64 includes eight bonding pads (electrodes) in this example, three of which are a power input pad for output signals, a ground pad (zero potential), and a signal output pad, and the remaining five are This is a signal adjustment pad.

In the base 40, a plurality of (for example, eight) terminal pins 70 and 72 penetrating the base 40 are provided around the semiconductor-type pressure detection device 60 by being hermetically sealed by a hermetic seal 74.
One of the plurality of terminal pins functions as the ground terminal pin 72. The ground terminal pin 72 and the other seven terminal pins 70 are connected to the relay board 90.

The power input pad and signal output pad formed in the semiconductor type pressure detecting device 60 (pressure detecting element 64) are connected to two of the plurality of terminal pins 70, and the ground pad is connected to the ground terminal pin 72. Is done. These three terminal pins 70 and 72 are connected to each of the lead wires 94 through a metal wiring pattern provided on the relay board 90 and a connector 92 attached to the relay board 90.
Further, the lead wire 94 is connected to an electric circuit (not shown) provided in a control panel such as a freezer / refrigerator or an air conditioner in which the pressure sensor 1 is installed. Thereby, the ground terminal pin 72 is connected to the external ground via the lead wire 94.

The plurality of terminal pins 70 and 72 connected to the relay board 90 may be only output terminal pins connected to the three pads for outputting output signals. At least one of the five terminal pins 70 connected to the formed signal adjustment pad may be further connected.
With such a configuration, the relay board 90 has a structure having connection points with the terminal pins 70 and 72 on both sides of the connector 92, so that a tensile force or the like is applied to the lead wire 94. Even so, no lateral stress is applied to the terminal pins 70 and 72, and as a result, the hermetic seal 74 that fixes the terminal pins 70 and 72 and the base 40 can be prevented from being damaged.

As shown in FIG. 2, among the bonding pads provided on the pressure detection element 64 of the semiconductor type pressure detection device 60, the seven bonding pads excluding the ground pad are respectively composed of seven terminal pins 70 and bonding wires 80. Electrically connected (connected). In addition, the ground pad is electrically connected (connected) with a neutralizing plate 100 described later and a bonding wire 81.
After the pressure detection unit 2 is disposed in the cover 10, the inside of the cover 10 is formed from the large-diameter opening 10 a side and the small-diameter opening 10 b side (the side from which the lead wire 94 is led out) of the cover 10. The resin P is filled and solidified, whereby the pressure detection unit 2 is fixed in the cover 10.

The fluid introduced into the connection nut 20 enters the fluid introduction chamber 32, and the diaphragm 50 is deformed by the pressure to pressurize the medium in the pressure receiving space 52.
The semiconductor-type pressure detecting element 64 detects this pressure fluctuation and converts it into an electric signal, and outputs the electric signal to the outside via the terminal pin 70.

In the pressure sensor 1 according to one embodiment of the present invention, the neutralizing plate 100 is attached to the base 40 with an adhesive or the like so as to surround the semiconductor type pressure detection device 60 (around the semiconductor type pressure detection device 60). .
The neutralization plate 100 has a polygonal planar shape, and is provided with a window hole 100a for enclosing the outer periphery of the semiconductor type pressure detection device 60 and a hole 100b for inserting the ground terminal pin 72 inside. It is.
In addition, the tip 72a of the ground terminal pin 72 inserted through the hole 100b provided in the charge removal plate 100 in a state where the charge removal plate 100 is attached to the base 40 is slightly from the upper surface 100c of the charge removal plate 100. The discharge plate 100 and the ground terminal pin are electrically connected by soldering 110 or the like (see FIG. 3).

  The ground terminal pin is connected to a zero potential (external ground) of an electric circuit provided in a control panel of a refrigerating / refrigeration apparatus or an air conditioner in which the pressure sensor 1 is installed via a lead wire 94. The electric potential charged around the semiconductor pressure detecting device 60 or the electric potential charged in the liquid medium filled in the pressure receiving space 52 is removed through the charge removing plate 100, thereby charging the semiconductor pressure detecting device 60. The resulting malfunction is prevented.

FIG. 3 is an enlarged view of a main part showing the positional relationship between the semiconductor pressure detector and the charge removal plate in the longitudinal sectional view shown in FIG.
As shown in FIG. 3, a pressure detection element 64 is attached to the base 40 on the pressure receiving space 52 side via a pedestal 62.
Further, a neutralizing plate 100 is attached to a position of the base 40 adjacent to the pressure detecting element 64, and a part thereof is electrically connected to the ground terminal pin 72 penetrating the base 40 by soldering 110. Yes.

In the pressure sensor according to the present invention, the height h2 from the surface of the base 40 to the surface of the charge removal plate 100 is configured to be higher than the height h1 from the surface of the base 40 to the surface of the pressure detection element 64. ing.
When the pressure sensor according to the present invention having such a configuration is charged by, for example, static electricity, the pressure detection element 64 and the charge removal plate 100 form an apparent capacitor (capacitor) with the diaphragm 50, respectively.

At this time, as described above, the height h2 from the base 40 to the surface of the charge removal plate 100 is configured to be higher than the height h1 from the base 40 to the surface of the pressure detection element 64. The surface of 100 is arranged at a position closer to the diaphragm 50 than the surface of the pressure detection element 64.
Further, since the inter-surface distance is reduced, the capacity between the static elimination plate 100 and the diaphragm 50 is larger than the capacity between the pressure detection element 64 and the diaphragm 50.
Accordingly, the charged electric charge is accumulated on the surface of the charge removal plate 100 with priority over the surface of the pressure detection element 64, and as a result, it is possible to prevent the pressure detection element 64 from malfunctioning due to charging. Can do.

The neutralization plate 100 is, for example, a structure in which an insulating material rich in heat resistance such as an inorganic material such as ceramics or glass, or polyamide, polyimide, polyethylene terephthalate (PET), or PPS is provided, and a conductive layer is formed on one surface thereof. And is fixed onto the base 40 via an adhesive layer. At this time, the conductive layer may be formed as a metal plate, or may be formed by printing or baking.
As the material for the conductive layer, gold, silver, copper, aluminum, nickel and the like are typical, but tungsten, molybdenum and the like can use a high melting point material in order to obtain high voltage durability.

In the above embodiment, the case where the neutralization plate 100 is arranged in a manner surrounding the semiconductor pressure detection device 60 is illustrated, but the neutralization plate 100 is only a part (side surface) around the semiconductor pressure detection device 60. You may comprise so that it may attach to.
In this case, since the static elimination plate 100 can be reduced in size compared with what surrounds the circumference | surroundings of the semiconductor type pressure detection apparatus 60, the whole pressure sensor can be reduced in weight.

As described above, in the pressure sensor according to the present invention, the neutralization plate 100 is set at a position where the height from the base 40 is higher than the height from the base 40 of the semiconductor-type pressure detection device 60. In other words, the surface height position of the charge removal plate 100 is configured to be closer to the diaphragm 50 than the surface height position of the semiconductor-type pressure detection device 60.
Thus, even when the pressure sensor is charged for some reason, the charge can be concentrated preferentially between the static elimination plate 100 and the diaphragm 50 and can be released to the outside via the ground terminal pin. The neutralization of the sensor can be carried out effectively.
Therefore, the pressure sensor according to the present invention can effectively remove the charge in the pressure receiving space 52 and more reliably prevent the malfunction of the semiconductor pressure detecting device 60.

The pressure sensor according to the present invention is provided with a static eliminating plate around or at a side position of the semiconductor type pressure detecting device, thereby preventing the influence of static electricity in the pressure receiving space and improving the reliability as the sensor. be able to.
Further, the static elimination plate 100 and the ground terminal pin 72 are electrically connected by soldering 110, but the present invention is not particularly limited to this, and caulking, crimping, press fitting, welding Alternatively, they may be electrically connected by a technique such as adhesion using a conductive adhesive or connection using a bonding wire.

DESCRIPTION OF SYMBOLS 1 Pressure sensor 10 Cover 20 Connection nut 30 Mounting member 32 Fluid introduction chamber 40 Base 50 Diaphragm 52 Pressure receiving space 60 Semiconductor type pressure detection apparatus 62 Base 64 Pressure detection element 70 Terminal pin 72 Ground terminal pin 74 Hermetic seal 80 Bonding wire 81 For earth Bonding wire 90 Relay board 92 Connector 94 Lead wire 100 Static elimination board

Claims (4)

A diaphragm for receiving the pressure of the fluid;
A base in which a pressure receiving space in which an insulating medium such as oil is sealed is formed between the diaphragm and the diaphragm;
A semiconductor-type pressure detection device provided in the pressure receiving space and provided with a plurality of bonding pads including a ground pad;
A pressure sensor comprising a plurality of terminal pins implanted in the base and electrically connected to the semiconductor type pressure detecting device, and one ground terminal pin connected to a zero potential of the semiconductor type pressure detecting device. ,
On the base, a neutralization plate is provided at a peripheral position of the semiconductor-type pressure detection device,
The charge removal plate is disposed so that the height from the base is higher than the height from the base of the semiconductor pressure detector,
The pressure sensor, wherein the static eliminating plate is electrically connected to an earth pad and the earth terminal pin of the semiconductor type pressure detecting device.   The pressure sensor according to claim 1, wherein the static eliminating plate is electrically connected to the ground terminal pin by soldering. A diaphragm for receiving the pressure of the fluid;
A base in which a pressure receiving space in which an insulating medium such as oil is sealed is formed between the diaphragm and the diaphragm;
A semiconductor-type pressure detection device provided in the pressure receiving space and provided with a plurality of bonding pads including a ground pad;
A pressure sensor comprising a plurality of terminal pins implanted in the base and electrically connected to the semiconductor type pressure detecting device, and one ground terminal pin connected to a zero potential of the semiconductor type pressure detecting device. ,
On the base, a neutralization plate is provided in a part of the peripheral position of the semiconductor type pressure detection device,
The charge removal plate is disposed so that the height from the base is higher than the height from the base of the semiconductor pressure detector,
The pressure sensor, wherein the static eliminating plate is electrically connected to an earth pad and the earth terminal pin of the semiconductor type pressure detecting device.   The pressure sensor according to claim 3, wherein the charge removal plate is electrically connected to the ground terminal pin by soldering.

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