Shielding structure of a pressure sensor and a pressure sensor having the shielding structure

Abstract

The present invention provides a pressure sensor. A lid-shaped shielding member (17) shields an unwanted electric field for a signal processing electronic circuit portion of a sensor chip (16), and is supported on an end face of a disk-shaped conductive plate (19) between one end face of the sensor chip (16) in a liquid seal chamber (13) and a diaphragm (32). The conductive plate (19) is electrically connected to an input / output terminal group (40ai) via a bonding wire (Wi), for example, and the sensor chip (16) is supported on one end portion of a chip mounting member (18) that is electrically connected to the input / output terminal group (40ai) via the bonding wire (Wi).

Description

[0001] This application is a divisional application; the application number of its parent application is "2018800768116", and the invention title is "Shielding Structure of Pressure Sensor and Pressure Sensor Having the Same". Technical Field

[0002] The present invention relates to a shielding structure of a pressure sensor and a pressure sensor having the same. Background Art

[0003] For example, as shown in Patent Document 1, a sensor unit built in a liquid-sealed semiconductor pressure sensor is configured to include the following components as main elements: a metal diaphragm that is supported within a joint portion and isolates a pressure detection chamber from a liquid-sealed chamber described below; a liquid-sealed chamber that is formed above the metal diaphragm and stores silicone oil as a pressure transmission medium; a sensor chip that is disposed within the liquid-sealed chamber and detects a pressure change of the silicone oil via the metal diaphragm; a sensor chip mounting member that supports the sensor chip; a sealing glass that seals around the sensor chip mounting member at a through-hole of a housing; and a terminal group (lead pins) that sends out an output signal from the sensor chip and supplies power to the sensor chip.

[0004] In the above structure, the metal diaphragm, the base plate, and the joint portion are connected at the same potential, and the above parts are insulated from the sensor chip. When insulation between a primary-side power source as a power source and a secondary-side power source of a control circuit that processes an output signal of the sensor chip is insufficient, since the impedance on the sensor chip side is high, a potential difference is generated between the opposed metal diaphragm and the sensor chip. In order to prevent the influence (output variation of the pressure sensor) of the potential generated between the metal diaphragm and the sensor chip on the electronic circuit and non-volatile memory within the sensor chip, for example, as shown in Patent Document 1, the following technology has been proposed: a metal lower plate and a metal member are provided at an end face of the sealing glass so as to surround the sensor chip and form a cylindrical space. The sensor chip is electrically connected to lead pins and the metal member that are connected to a zero potential of an electronic circuit integrated in the sensor chip via a pressing plate. As a result, the potential of the lower plate and the metal member is the same zero potential as the electronic circuit of the sensor chip located within the space surrounded by the lower plate and the metal member, and thus there is no potential difference between the metal diaphragm and the sensor chip. Consequently, there is no concern about an electric field that affects the electronic circuit of the sensor chip.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent No. 3987386 Gazette Summary of the Invention

[0008] As a countermeasure in such a case, for example, consider the following countermeasures: additionally dispose the above-mentioned pressing plate, which is connected to the lead pins protruding from the other end face of the sealing glass isolated from the above-mentioned liquid-sealing chamber, and is electrically connected to the lead pins in other processes, etc., to connect the lead pins to the zero potential of the electronic circuit integrated in the sensor chip.

[0009] However, the configuration of another pressing plate and the operation of connecting the lead pins to the pressing plate are required, whereby the number of components and the assembly operation process of the pressure sensor increase, which is not a good solution.

[0010] Considering the above problems, an object of the present invention is to provide a shielding structure of a pressure sensor and a pressure sensor having the shielding structure, in which the shielding structure of the pressure sensor and the pressure sensor having the shielding structure can reduce the influence on the electric field generated between the sensor chip and the metal diaphragm in the pressure sensor without increasing the number of components and the assembly operation process.

[0011] To achieve the above object, the shielding structure of the pressure sensor of the present invention is configured to include a sensor unit and an electric field shielding member. Among them, the sensor unit includes: a sensor chip that detects pressure and sends out a detection output signal; a chip mounting member that supports the sensor chip; a diaphragm that separates the liquid-sealing chamber in which the sensor chip and the chip mounting member are disposed from the pressure chamber opposed to the liquid-sealing chamber; and an input / output terminal group that is supported by the sealing glass and electrically connected to the sensor chip. The electric field shielding member is disposed between one end face of the sensor chip in the liquid-sealing chamber and the diaphragm by being supported by a conductive plate electrically connected to the input / output terminal group, and shields the electric field acting on the signal processing electronic circuit portion of the sensor chip. Preferably, the conductive plate is disposed on the end face of the sealing glass and electrically connected to the input / output terminal group. Preferably, the conductive plate and the signal processing electronic circuit portion of the sensor chip are at the same potential.

[0012] Furthermore, the shielding structure of the pressure sensor of the present invention is configured to include a sensor unit and an electric field shielding member. Among them, the sensor unit includes: a sensor chip that detects pressure and sends out a detection output signal; a diaphragm that separates the liquid-sealing chamber in which the sensor chip is disposed from the pressure chamber opposed to the liquid-sealing chamber; and an input / output terminal group that is electrically connected to the sensor chip. The electric field shielding member is disposed between one end face of the sensor chip in the liquid-sealing chamber and the diaphragm by being supported by a conductive plate electrically connected to the input / output terminal group, and shields the electric field acting on the signal processing electronic circuit portion of the sensor chip. Preferably, the conductive plate is disposed on the inner peripheral surface of the sensor housing that houses the sensor unit and electrically connected to the input / output terminal group. Preferably, the conductive plate and the signal processing electronic circuit portion of the sensor chip are at the same potential.

[0013] In addition, the shielding structure of the pressure sensor of the present invention is configured to include a sensor unit and an electric field shielding member. The sensor unit includes: a sensor chip that detects pressure and sends out a detection output signal; a chip mounting member that supports the sensor chip; a diaphragm that separates a liquid-sealed chamber in which the sensor chip and the chip mounting member are disposed from a pressure chamber opposed to the liquid-sealed chamber; and an input / output terminal group that is supported by a sealing glass and electrically connected to the sensor chip. The electric field shielding member is disposed between one end face of the sensor chip in the liquid-sealed chamber and the diaphragm by being disposed on the end face of the sealing glass and electrically connected to the input / output terminal group, and shields the electric field acting on the signal processing electronic circuit portion of the sensor chip. Preferably, the electric field shielding member and the signal processing electronic circuit portion of the sensor chip are at the same potential.

[0014] Furthermore, the shielding structure of the pressure sensor of the present invention is configured to include a sensor unit and an electric field shielding member. The sensor unit includes: a sensor chip that detects pressure and sends out a detection output signal; a chip mounting member that supports the sensor chip; a diaphragm that separates a liquid-sealed chamber in which the sensor chip and the chip mounting member are disposed from a pressure chamber opposed to the liquid-sealed chamber; and an input / output terminal group that is electrically connected to the sensor chip and the chip mounting member. The electric field shielding member is disposed between one end face of the sensor chip in the liquid-sealed chamber and the diaphragm by being disposed on the end face of the chip mounting member and electrically connected to the input / output terminal group, and shields the electric field acting on the signal processing electronic circuit portion of the sensor chip. Preferably, the electric field shielding member and the signal processing electronic circuit portion of the sensor chip are at the same potential.

[0015] The pressure sensor of the present invention is constituted by including a sensor unit, an electric field shielding member, and a sensor unit housing portion that houses the sensor unit and the electric field shielding member. The sensor unit includes: a sensor chip that detects pressure and sends out a detection output signal; a chip mounting member that supports the sensor chip; a diaphragm that separates a liquid-sealed chamber in which the sensor chip and the chip mounting member are disposed from a pressure chamber opposed to the liquid-sealed chamber; and an input / output terminal group that is supported by a sealing glass and electrically connected to the sensor chip. The electric field shielding member is disposed between one end face of the sensor chip in the liquid-sealed chamber and the diaphragm by being supported by a conductive plate that is electrically connected to the input / output terminal group together with the chip mounting member, and shields the electric field acting on the signal processing electronic circuit portion of the sensor chip.

[0016] Furthermore, the pressure sensor of the present invention includes a sensor unit, an electric field shielding member, and a sensor unit housing portion that houses the sensor unit and the electric field shielding member. The sensor unit includes: a sensor chip that detects pressure and outputs a detection output signal; a diaphragm that separates a liquid-sealed chamber in which the sensor chip is disposed from a pressure chamber opposed to the liquid-sealed chamber; and an input / output terminal group that is electrically connected to the sensor chip. The electric field shielding member is supported by a conductive plate electrically connected to the input / output terminal group and is disposed between one end face of the sensor chip in the liquid-sealed chamber and the diaphragm to shield the electric field acting on the signal processing electronic circuit portion of the sensor chip. Preferably, the electric field shielding member and the signal processing electronic circuit portion of the sensor chip are at the same potential.

[0017] According to the shielding structure of the pressure sensor of the present invention and the pressure sensor having the shielding structure, since there is an electric field shielding member that is supported by a conductive plate electrically connected to the input / output terminal group and is disposed between one end face of the sensor chip in the liquid-sealed chamber and the diaphragm to shield the electric field acting on the signal processing electronic circuit portion of the sensor chip, it is possible to reduce the influence on the electric field generated between the sensor chip and the metal diaphragm in the pressure sensor without increasing the number of components and the assembly operation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a cross-sectional view of a main part showing an example of the shielding structure of the pressure sensor of the present invention.

[0019] Figure 2 is from Figure 1 a front view of the electric field shielding member disposed in the liquid-sealed chamber as viewed from the direction of the arrow shown.

[0020] Figure 3 is a cross-sectional view showing the structure of an example of a pressure sensor applying an example of the shielding structure of the pressure sensor shown in Figure 1 is a cross-sectional view showing the structure of an example of a pressure sensor applying an example of the shielding structure of the pressure sensor shown in

[0021] Figure 4 is a cross-sectional view of a main part showing another example of the shielding structure of the pressure sensor of the present invention.

[0022] Figure 5 is a partially enlarged view showing Figure 4 part V in the example shown in an enlarged manner.

[0023] Figure 6 is from Figure 5 a front view of the electric field shielding member disposed in the liquid-sealed chamber as viewed from the direction of the arrow shown.

[0024] Figure 7It is a cross-sectional view of the main part showing another example of the shielding structure of the pressure sensor of the present invention.

[0025] Figure 8 It shows Figure 7 A top view of the electric field shielding member in the liquid seal chamber in the example shown.

[0026] Figure 9 It is a cross-sectional view of the main part showing another example of the shielding structure of the pressure sensor of the present invention.

[0027] Figure 10 It is a partially enlarged view showing Figure 9 A partially enlarged view of part X in the example shown.

[0028] Figure 11 It is from Figure 10 A front view of the electric field shielding member arranged in the liquid seal chamber as observed from the direction of the arrow shown.

[0029] Figure 12A It is a perspective view showing another example of the conductive plate used in the example shown, including a partial cross-section. Figure 7 A perspective view of another example of the conductive plate used in the example shown.

[0030] Figure 12B It shows Figure 12A A cross-sectional view of the state where the conductive plate shown is mounted on the sensor housing.

[0031] Figure 12C It is a cross-sectional view showing another example of the conductive plate used in the example shown in the state of being mounted on the sensor housing. Figure 7 A cross-sectional view of another example of the conductive plate used in the example shown. Detailed Description

[0032] Figure 3 Briefly shows the structure of a pressure sensor applying an example of the shielding structure of the pressure sensor of the present invention.

[0033] Figure 3 Among them, the pressure sensor is configured to include a joint member 30 and a sensor unit housing portion. The joint member 30 is connected to a pipe that guides the fluid whose pressure should be detected. The sensor unit housing portion is connected to the base plate 28 of the joint member 30 by, for example, brazing, etc., houses the following sensor unit, and supplies the detection output signal from the sensor chip to a predetermined pressure measuring device.

[0034] The metal joint member 30 has an internal thread portion 30fs on the inner side thereof, which has an external thread portion to be screwed into the connection portion of the above-mentioned pipe. The internal thread portion 30fs communicates with the port 30a of the joint member 30 that guides the fluid supplied from the direction indicated by the arrow P to the following pressure chamber 28A. One open end of the port 30a opens toward the pressure chamber 28A formed between the base plate 28 of the joint member 30 and the diaphragm 32 of the sensor unit.

[0035] The outer contour portion of the sensor unit housing portion is formed by a cylindrical waterproof housing 20 as a cover member. An opening portion 20b is formed at the lower end portion of the resin-made waterproof housing 20. The peripheral portion of the base plate 28 of the joint member 30 is engaged with the stepped portion on the periphery of the inner opening portion 20b.

[0036] The pressure of the fluid is introduced into the pressure chamber 28A via the port 30a of the joint member 30.

[0037] The lower end surface of the housing 12 of the sensor unit is connected to the peripheral portion of the base plate 28 by welding.

[0038] The sensor unit detects the pressure in the pressure chamber 28A and sends out a detection output signal. The sensor unit is configured to include the following components as main elements: a metal cylindrical housing 12; a metal diaphragm 32 that isolates the pressure chamber 28A from the inner peripheral portion of the housing 12; a sensor chip 16 that has a plurality of pressure detection elements and a signal processing electronic circuit portion for processing signals from the pressure detection elements; a metal chip mounting member 18 that supports the sensor chip 16 at one end via an adhesive layer 50; an input / output terminal group 40ai (i = 1 to 8) that is electrically connected to the sensor chip 16; and a sealing glass 14 that fixes the input / output terminal group 40ai and the filling oil pipe 44 between the outer peripheral surface of the chip mounting member 18 and the inner peripheral surface of the housing 12.

[0039] The diaphragm 32 is supported on the lower end surface of the housing 12 on the side facing the above-mentioned pressure chamber 28A. A diaphragm protection cover 34 protects the diaphragm 32 disposed in the pressure chamber 28A, and the diaphragm protection cover 34 has a plurality of communication holes 34a. The periphery of the diaphragm protection cover 34 is joined to the periphery of the diaphragm 32 and the lower end surface of the housing 12 by welding. The housing 12, the diaphragm 32, the base plate 28, and the joint member 30 are connected and conduct electricity, so as to be at the same potential. And the input / output terminal group 40ai and the chip mounting member 18 are held insulated from the housing 12 via an insulator such as the sealing glass 14, for example.

[0040] A liquid seal chamber 13 is formed between the end faces of a metal diaphragm 32 and the opposed sensor chip 16 and sealing glass 14. For example, a pressure transmission medium PM such as a predetermined amount of silicone oil or a fluorine-based inert liquid is filled into the liquid seal chamber 13 via a filling oil tube 44. Further, after filling the oil, one end of the filling oil tube 44 is crushed and closed as shown by the double-dashed line.

[0041] The input / output terminal group 40ai (i = 1 to 8) is composed of two power supply terminals, one output terminal, and five adjustment terminals. Both end portions of each terminal project from the end of the above-mentioned sealing glass 14 toward the liquid seal chamber 13, or project into the holes 24b of the following terminal block 24. The two power supply terminals and one output terminal are connected to the core wires 38a of the respective wires 38 via connection terminals 36. Each wire 38 is connected to a predetermined pressure measuring device, for example. Further, Figure 3 Only four of the eight terminals are shown. The input / output terminal group 40ai is connected to the following sensor chip 16 via bonding wires Wi.

[0042] The terminal block 24 that arranges the input / output terminal group 40ai is formed of a resin material such as polybutylene terephthalate (PBT) as the main component. The terminal block 24 has a plurality of holes 24b into which the input / output terminal group 40ai is inserted, and has a cavity 24A with a predetermined volume inside. The terminal arrangement portion 24T has a plurality of holes 24b isolated from each other and is integrally formed in a manner orthogonal to the above-mentioned base end portion. The lower end face of the base end portion of the terminal block 24 serving as the bonding surface is bonded to the upper end face of the housing 12 using a silicone-based adhesive. Thus, a ring-shaped bonding layer 10a with a predetermined thickness is formed on the upper end face of the housing 12. And, on the entire upper end face of the sealing glass 14 where the input / output terminal group 40ai projects, a coating layer 10b made of a silicone-based adhesive is formed with a predetermined thickness.

[0043] A sealing material 26 is filled in a predetermined amount between the outer peripheral surface of the terminal block 24 as a terminal arrangement member and the inner peripheral surface of the waterproof housing 20, and between the inner peripheral surface of the waterproof housing 20 and the outer peripheral surface of the housing 12, and also between the outer peripheral surface of the end cap 22 that is connected to the terminal block 24 and covers the holes 24b of the above-mentioned terminal arrangement portion 24T and the upper open end of the terminal block 24. The terminal block 24 and the end cap 22 are arranged in the waterproof housing 20 so as to face the base plate 28 of the joint member 30 with the above-mentioned sensor unit interposed therebetween. The upper end face of the end cap 22 projects upward from the open end of the waterproof housing 20. That is, the position of the upper end face of the end cap 22 is higher than the position of the open end face of the waterproof housing 20.

[0044] The sensor chip 16 is bonded to one end portion of a chip mounting member 18 that forms the inside of the liquid seal chamber 13 via an adhesive layer 50, for example. AsFigure 1 As shown, the outer dimensions of the generally rectangular sensor chip 16 are set to be larger than the diameter of the chip mounting member 18.

[0045] In the liquid seal chamber 13, for example, a disk-shaped conductive plate 19 is supported on one end face of the sealing glass 14 so as to surround the sensor chip 16. The conductive plate 19 is formed of any one of insulating materials such as resin, glass, and ceramic, and one end face thereof is formed of a conductive layer formed by adhesion, evaporation, electroplating, etc., that is, a metal film such as gold, silver, copper, or aluminum, and is integrated. One end face of the above-mentioned conductive plate 19 that serves as the conductive layer faces the diaphragm 32, and the conductive plate 19 is supported on the sealing glass 14 at the other end face that serves as the insulating layer.

[0046] And, between one end face of the sensor chip 16 in the liquid seal chamber 13 and the diaphragm 32, a shielding member 17 serving as an electric field shielding member is provided. The shielding member 17 shields an electric field that is not desired for the signal processing electronic circuit portion of the sensor chip 16.

[0047] The shielding member 17 can be made of a conductive metal material such as stainless steel, copper, or aluminum, or can also be made of an insulating material such as resin, glass, or ceramic, for example, and its surface layer is formed of a conductive metal formed by film formation such as bonding, evaporation, sputtering, or electroplating and is integrated.

[0048] As Figure 2 As shown, the four fixed ends of the lid-shaped shielding member 17 are closely joined to the outer periphery of the sensor chip 16 at one end face of the disk-shaped conductive plate 19 and are electrically connected thereto. A plurality of openings are provided on the side surface of the shielding member 17, and illustration thereof is omitted. The shape of the shielding member 17 is such that the pressure transmission medium PM can move, so that the pressure corresponding to the displacement of the diaphragm 32 is transmitted to the sensor chip 16 via the pressure transmission medium PM.

[0049] The conductive plate 19 is connected and electrically connected to any one or more of the input / output terminal groups 40ai, for example, the zero (V) terminal, via the bonding lead Wi. According to such a structure, the potentials of the shielding member 17 and the conductive plate 19 are the same as those of the electronic circuit mounted on the sensor chip 16.

[0050] A predetermined gap is formed between the portion of the shielding member 17 that covers the entire sensor chip 16 and the end face of the sensor chip 16. In addition, the outer dimensions of the shielding member 17 can also be appropriately set according to the size of the signal processing electronic circuit portion of the sensor chip 16 so as to shield an electric field that is not desired for the signal processing electronic circuit portion of the sensor chip 16.

[0051] Therefore, by disposing a shielding member 17 having the same potential as that of the sensor chip 16 between the diaphragm 32 and the signal processing electronic circuit portion of the sensor chip 16, the shielding member 17 blocks the electric field acting on the sensor chip 16 generated by the potential difference between the diaphragm 32 having the same potential as the primary side power supply (not shown) of the sum unit and the control circuit (not shown) side. And since the potentials of the shielding member 17 and the sensor chip 16 are the same potential, no electric field is generated between them. Therefore, the potential difference generated between the sensor chip 16 and the diaphragm 32 does not act on the sensor chip 16, thereby preventing an influence on the electronic circuit in the sensor chip 16.

[0052] Figure 4 Partially shown is a main part of a pressure sensor showing another example of a shielding structure of a pressure sensor to which the present invention is applied.

[0053] In Figure 1 the example shown, the four fixed ends of the lid-shaped shielding member 17 are, for example, closely joined to the outer periphery of the sensor chip 16 at the end face of the disc-shaped conductive plate 19, but alternatively, in Figure 4 the example shown, the shielding plate 48 is supported on the end face of the sealing glass 14 in the liquid sealing chamber 13.

[0054] In addition, Figures 4 to 6 in, the same reference numerals are used to denote the same components as those in Figure 1 and Figure 3 the example shown, and the repeated description thereof is omitted.

[0055] In such a pressure sensor, it is also configured to include a joint member and a sensor unit accommodating portion, wherein the joint member is connected to a pipe for guiding a fluid whose pressure should be detected, the sensor unit accommodating portion is connected to the base plate material of the joint member, accommodates the following sensor unit, and supplies a detection output signal from the sensor chip to a predetermined pressure measuring device, which is omitted from illustration.

[0056] Between one end face of the sensor chip 16 in the liquid sealing chamber 13 and the diaphragm 32, a shielding plate 48 as an electric field blocking member is provided. The shielding plate 48 blocks an unwanted electric field for the signal processing electronic circuit portion of the sensor chip 16. The shielding plate 48 can be made of a conductive metal material such as stainless steel, copper, aluminum, etc., or the shielding plate 48 can also be made of an insulating material such as resin, glass, ceramic, etc., and a conductive layer of a conductive metal formed by bonding, evaporation, sputtering, electroplating, etc. is formed on one surface layer thereof and integrated. As Figure 6As shown, the strip-shaped shielding plate 48 is composed of a groove-shaped portion 48A facing one end face of the sensor chip 16, a first fixing portion 48B and a second fixing portion 48C connected to both end portions of the groove-shaped portion 48A. The groove-shaped portion 48A, the first fixing portion 48B and the second fixing portion 48C are integrally formed by, for example, stamping. The groove-shaped portion 48A passes directly above the central portion of the sensor chip 16 with a predetermined gap. A tube 44 for filling oil is press-fitted into the hole 48b of the first fixing portion 48B, and each input / output terminal group 40ai protruding from the end face of the sealing glass 14 is inserted into the holes 48f, 48d and the cutout portion 48e of the second fixing portion 48C. Thus, the first fixing portion 48B and the second fixing portion 48C approach the outer peripheral portion of the sensor chip 16 at one end portion of the chip mounting member 18 and abut against and support the end face of the sealing glass 14.

[0057] The second fixing portion 48C is electrically connected, via a bonding wire Wi, to one of the input / output terminal groups 40ai, for example, to zero (V). The input / output terminal group 40ai is connected to one end face which is the conductor surface of the shielding plate 48. With such a structure, the potential of the conductor surface which is one end face of the shielding plate 48 is at the same potential as the electronic circuit mounted on the sensor chip 16.

[0058] In addition, the outer dimension and the width dimension of the shielding plate 48 can also be appropriately set according to the size of the signal processing electronic circuit portion of the sensor chip 16 so as to shield an unwanted electric field for the signal processing electronic circuit portion of the sensor chip 16.

[0059] Therefore, by disposing the shielding plate 48 having the same potential as the signal processing electronic circuit portion of the sensor chip 16 between the diaphragm 32 and the sensor chip 16, the shielding plate 48 shields the electric field acting on the sensor chip 16 due to the potential difference between the diaphragm 32 having the same potential as the primary side power supply (not shown) of the sum unit and the control circuit (not shown) side. And since the potential of the shielding plate 48 and the potential of the sensor chip 16 are the same potential, no electric field is generated between them. Therefore, the potential difference caused by the potential difference generated between the sensor chip 16 and the diaphragm 32 does not act on the sensor chip 16, and thus it is possible to prevent an influence on the electronic circuit in the sensor chip 16.

[0060] Figure 7 The structure of a pressure sensor which locally shows another example of the shielding structure of the pressure sensor to which the present invention is applied is shown.

[0061] Figure 7The pressure sensor shown is configured to include a joint member 60 and a metallic sensor housing 56. Among them, the joint member 60 is connected to a pipe that guides the fluid whose pressure should be detected, and the metallic sensor housing 56 connects the joint member 60 and the base plate 58 by brazing or the like and houses the following sensor unit.

[0062] One open end of the port 60a of the joint member 60 opens toward the pressure chamber 58A formed between the base plate 58 of the joint member 60 and the diaphragm 70 of the sensor unit.

[0063] The sensor unit that detects the pressure in the pressure chamber 58A and outputs a detection output signal is configured to include the following components as main elements: a metallic diaphragm 70 that isolates the pressure chamber 58A from the inner peripheral portion of the sensor housing 56; a sensor chip 66 that has a plurality of pressure detection elements and a signal processing electronic circuit portion that processes signals from the pressure detection elements; a conductive plate 62 that has a hole into which the outer peripheral portion of the sensor chip 66 is inserted and surrounds the sensor chip 66; and an input / output terminal group 54ai (i = 1 to 8) that is electrically connected to the sensor chip 66.

[0064] The metallic diaphragm 70 is fixedly welded between the joint end of the above-mentioned sensor housing 56 and the joint end of the base plate 58. Therefore, the potential of the sensor housing 56 is connected and conducted with the diaphragm 70, the base plate 58, and the joint member 60, and thus is at the same potential as the potential of the diaphragm 70 and the like.

[0065] In the sealed space formed by the diaphragm 70 and the inner peripheral portion of the sensor housing 56, that is, the liquid seal chamber 68, for example, a pressure transmission medium PM such as a predetermined amount of silicone oil or a fluorine-based inert liquid is filled. After filling the pressure transmission medium PM through the hole 56a of the sensor housing 56, the hole 56a is blocked by the plug member 52. The input / output terminal group 54ai is supported in insulation from the sensor housing 56 via a sealing glass 65 (refer to Figure 8 ). The input / output terminal group 54ai is connected to the sensor chip 66 by bonding wires Wi.

[0066] In the liquid seal chamber 68, for example, a rectangular conductive plate 62 is supported on the inner peripheral surface of the sensor housing 56 so as to surround the sensor chip 66. The conductive plate 62 can be made of any insulating material such as resin, glass, or ceramic, and a conductive layer, that is, a metal film such as gold, silver, copper, or aluminum, is formed on one end face by adhesion, evaporation plating, electroplating, or the like and integrated. One end face of the conductive plate 62 that serves as the conductive layer faces the diaphragm 70, and the insulating layer on the other end face is supported by the sensor housing 56. And, between one end face of the sensor chip 66 and the diaphragm 70 in the liquid seal chamber 68, a shielding member 64 serving as an electric field shielding member is provided.

[0067] In addition, for example, as Figure 12A shown, the conductive plate may also be composed of a core member 63 made of an insulating material and a cover member 67 made of a conductive material and covering the core member 63. In addition, Figures 12A to 12C the illustration of the shielding member 64 is omitted.

[0068] At the inner peripheral edge of the annular core member 63, there is a stepped portion 63R adjacent to one end face. The cover member 67 is composed of the following members: a disc-shaped portion 67A that covers the other end face of the core member 63 facing the diaphragm 70; an inner peripheral edge portion 67C that is connected to the disc-shaped portion 67A and covers the inner portion of the core member 63; and a fixing portion 67B that is connected to the inner peripheral edge portion 67C and is fixed to the stepped portion 63R of the core member 63 by riveting. One end face of the core member 63 of the conductive plate is bonded to the inner peripheral surface of the sensor housing 56. At this time, as Figure 12B shown, by forming a predetermined gap between the fixing portion 67B of the cover member 67 at the conductive plate and the inner peripheral surface of the sensor housing 56, and between the outer peripheral surface of the sensor chip 66 and the inner peripheral edge portion 67C of the cover member 67 at the conductive plate, contact between the sensor housing 56 and the cover member 67 is prevented.

[0069] And, for example, as Figure 12C shown, the conductive plate may also be composed of a core member 63' made of an insulating material and a cover member 67' made of a conductive material and covering the core member 63'. The annular core member 63' has a thin-walled protruding portion 63'F at its outer peripheral edge. The cover member 67' is composed of the following members: a disc-shaped portion 67'A that covers the other end face of the core member 63' facing the diaphragm 70; an outer peripheral edge portion 67'C that is connected to the disc-shaped portion 67'A and covers the outer portion of the protruding portion 63'F of the core member 63'; and a fixing portion 67'B that is connected to the outer peripheral edge portion 67'C and is fixed to one end face of the protruding portion 63'F of the core member 63' by riveting. The end face around the inner peripheral edge of the core member 63' of the conductive plate is bonded to the inner peripheral surface of the sensor housing 56. At this time, as Figure 12C shown, by forming a predetermined gap between the fixing portion 67'B of the cover member 67' at the conductive plate and the inner peripheral surface of the sensor housing 56, and between the outer peripheral surface of the sensor chip 66 and the inner peripheral edge portion 67'a of the cover member 67' at the conductive plate and the inner peripheral surface of the core member 63', contact between the sensor housing 56 and the cover member 67' is prevented.

[0070] The shielding member 64 can be made of a conductive metal material such as stainless steel, copper, aluminum, etc., or the shielding member 64 can also be made of an insulating material such as resin, glass, ceramic, etc., and one surface layer is formed of a conductive metal film formed by film formation such as bonding, evaporation plating, sputtering, electroplating, etc. and integrated. That is, the shielding member 64 is supported via an insulator (the insulating layer of the conductive plate 62) on the sensor housing 56 having the same potential as the primary side potential.

[0071] The shielding member 64 covers the entire one end face of the sensor chip 66 with a predetermined interval therebetween to block an unwanted electric field for the signal processing electronic circuit portion of the sensor chip 66. The pair of fixed ends of the shielding member 64 and the conductive plate 62 are joined and conduct electricity with each other at the conductor surface. One end face of the conductive plate 62 serving as the conductor surface is joined and conducts electricity with any one or more of the input / output terminal groups 54ai, for example, the input / output terminal group 54ai for zero (V), via the bonding lead Wi. According to such a structure, the potentials of the shielding member 64 and the conductive plate 62 are the same as the potential of the electronic circuit mounted on the sensor chip 66.

[0072] Therefore, by disposing the shielding member 64 having the same potential as the signal processing electronic circuit portion of the sensor chip 66 between the diaphragm 70 and one end face of the sensor chip 66, the shielding member 64 blocks the electric field acting on the sensor chip 66 generated between the diaphragm 70 having the same potential as the primary side power supply (not shown) of the sum unit and the control circuit (not shown) side due to the potential difference. And since the potential of the shielding member 64 is the same as the potential of the sensor chip 66, no electric field is generated between them. Therefore, the potential difference generated between the sensor chip 66 and the diaphragm 70 does not act on the sensor chip 66, and thus it is possible to prevent an influence on the electronic circuit in the sensor chip 66.

[0073] Figure 9 Partially shows the main part of a pressure sensor showing another example of the shielding structure of the pressure sensor to which the present invention is applied.

[0074] In Figure 1 In the example shown, the four fixed ends of the lid-shaped shielding member 17 are joined close to the outer periphery of the sensor chip 16 at the end face of the disk-shaped conductive plate 19, but alternatively, in Figure 9 In the example shown, the shielding plate 17' is joined to the end face of the chip mounting member 18' facing the liquid seal chamber 13.

[0075] In addition, Figures 9 to 11 In, the same reference numerals are used to denote the constituent elements the same as those in the Figure 1 example shown, and the repeated description thereof is omitted.

[0076] The sensor chip 16 is bonded, for example, via an adhesive layer 50 to one end portion of a chip mounting member 18' that forms the inside of the liquid seal chamber 13. As Figure 9 shown, the outer dimensions of the substantially rectangular sensor chip 16 are set to be smaller than the diameter of the chip mounting member 18'. The chip mounting member 18' is connected and electrically conducted to any one or more of the input / output terminal groups 40ai, for example, the input / output terminal for zero (V), via the bonding lead Wi.

[0077] Between one end face of the sensor chip 16 in the liquid seal chamber 13 and the diaphragm 32, a shielding plate 17' serving as an electric field shielding member is provided. The shielding plate 17' shields an electric field that is not desired for the signal processing electronic circuit portion of the sensor chip 16. The shielding plate 17' can be made of, for example, a conductive metal material such as stainless steel, copper, or aluminum, or the shielding plate 17' can also be made of an insulating material such as resin, glass, or ceramic, and a conductive metal film formed by film formation such as bonding, evaporation, sputtering, or electroplating is formed and integrated on one surface of the surface layer of the shielding plate 17'.

[0078] The fixed end portion of the strip-shaped shielding plate 17' is closely joined to the outer peripheral portion of the sensor chip 16 at one end portion of the chip mounting member 18' and is electrically conducted. According to such a structure, the potentials of the shielding plate 17' and the chip mounting member 18' are at the same potential as the potential of the electronic circuit mounted on the sensor chip 16.

[0079] A predetermined gap is formed between the portion of the shielding plate 17' facing one end face of the sensor chip 16 and one end face of the sensor chip 16. In addition, the outer dimensions and width dimensions of the shielding plate 17' can also be appropriately set according to the size of the signal processing electronic circuit portion of the sensor chip 16 so as to shield an electric field that is not desired for the signal processing electronic circuit portion of the sensor chip 16.

[0080] And here, the input / output terminal 40ai and the bonding lead Wi are connected to the chip mounting member 18', but not limited to this example, and the input / output terminal 40ai and the bonding lead Wi can also be directly connected to the shielding member 17'.

[0081] Therefore, by disposing a shielding plate 17' having the same potential as the signal processing electronic circuit portion of the sensor chip 16 between the diaphragm 32 and the sensor chip 16, the shielding plate 17' blocks the electric field acting on the sensor chip 16 generated by the potential difference between the diaphragm 32 having the same potential as the primary side power supply (not shown) of the sum unit and the control circuit (not shown) side. And since the potential of the shielding plate 17' is the same as the potential of the sensor chip 16, no electric field is generated between them. Therefore, the potential difference generated between the sensor chip 16 and the diaphragm 32 does not act on the sensor chip 16, thereby preventing the electronic circuit in the sensor chip 16 from being affected.

[0082] From the above description, it is clear that in an example of the shielding structure of the pressure sensor according to the present invention, in the pressure sensor, the shielding plates 17', 48 or the shielding members 17, 64, the conductive plates 19, 62 are used to avoid the influence (output variation of the pressure sensor) on the electronic circuit in the sensor chip caused by the potential generated between the sensor chips 16, 66 and the diaphragms 32, 70, respectively. Thus, it is possible to reduce the influence on the electric field generated between the sensor chip and the diaphragm in the pressure sensor without increasing the number of components and the assembly operation process.

Claims

1. A shielding structure for a pressure sensor, characterized in that it is configured to include a sensor unit and an electric field shielding member, the above-mentioned sensor unit includes: a sensor chip that detects pressure and sends out a detection output signal; a chip mounting member made of metal, whose diameter is larger than the outer dimension of the sensor chip and supports the sensor chip; a diaphragm that separates the liquid-sealed chamber in which the sensor chip and the chip mounting member are arranged from the pressure chamber opposed to the liquid-sealed chamber; and an input / output terminal group that is electrically connected to the sensor chip and the chip mounting member, and the chip mounting member is electrically connected to at least one or more terminals in the input / output terminal group. The above-mentioned electric field shielding member is arranged between one end face of the sensor chip in the liquid-sealed chamber and the diaphragm, and is fixed to a position near the outer peripheral portion of the sensor chip of the chip mounting member and is electrically connected to the input / output terminal group via the chip mounting member, so as to shield the electric field acting on the signal processing electronic circuit portion of the sensor chip.

2. The shielding structure for a pressure sensor according to claim 1, characterized in that the above-mentioned electric field shielding member and the signal processing electronic circuit portion of the sensor chip are at the same potential.

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