Pressure sensor

Abstract

The utility model provides a cheap pressure sensor, which can reduce stress applied to a built-in circuit substrate, and can be used in a simple structure with high precision and high reliability, and liquid tightness is ensured. A pressure sensor (100) in which a sensor chip (11) for detecting the pressure of an object to be measured is connected to a circuit board (50) built in a housing (20), the sensor chip being provided in a pressure chamber (PR) so as to receive the pressure of the object to be measured. The circuit board constitutes a part of a space-forming member which is formed in a liquid-tight manner by filling the housing with a sealing material (26) and which forms an installation space (SR) in which a mounting member (50J) of the circuit board is installed.

Description

Technical Field

[0001] The utility model relates to a pressure sensor which is molded in a liquid-tight manner by resin. Background Art

[0002] Various sensors for detecting pressure, temperature, etc. are fixed near a measurement object and are used in a manner of sending a detection signal to a measurement device or the like, and are widely used in a manner of being built in or external to the measurement device.

[0003] Such various sensors can be installed in a sensor unit and used in a location exposed to the same environment as the object to be measured. For example, when it is necessary to change the electrical characteristics of the input and output to the sensor chip, a circuit board is sometimes built in (see Patent Document 1).

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent No. 6633597

[0006] However, in the pressure sensor described in Patent Document 1, Figure 5 As shown, the circuit board 1431 connected to the sensor chip 1121 in the housing 1124 is accommodated in a case 1135 , and the case 1135 is sealed liquid-tightly by filling a sealing material 1136 such as a resin material in the case 1135 .

[0007] In such a structure, there are differences in the linear expansion coefficients of constituent materials such as the circuit substrate 1431, the housing 1135, and the sealing material 1136. Therefore, when a temperature difference occurs between the inside and outside of the measurement object, stress corresponding to the temperature difference may be generated. This stress may become a load on the circuit substrate 1431 itself or a component mounted on the circuit substrate 1431. In addition, for devices such as pressure sensors, cost reduction has been required. Utility Model Content

[0008] Therefore, an object of the present invention is to provide an inexpensive pressure sensor that can reduce stress applied to a built-in circuit board, realize a simple structure that ensures liquid-tightness with high accuracy, and can be used with high reliability.

[0009] One method of the utility model of a pressure sensor that solves the above-mentioned problem is a pressure sensor, wherein a sensor for detecting the pressure of a measuring object is connected to a circuit substrate built into a housing, and the pressure sensor is characterized in that the sensor is arranged in a pressure chamber in a manner to withstand the pressure of the measuring object, and the circuit substrate constitutes a part of a space forming component that is formed liquid-tight by filling a sealing material in the housing and forms a setting space for a mounting component on which the circuit substrate is set.

[0010] The space forming component comprises: a side wall portion, which constitutes the side surface of the cylindrical shape; and a closing portion, which is located on one end edge side of the side wall portion in a manner of closing an opening of the cylindrical shape, and the circuit substrate is constructed and forms the setting space by closing the other end edge side of the side wall portion, that is, the other opening of the cylindrical shape.

[0011] The circuit substrate is arranged in a manner between the sensor and the external device, and the circuit substrate is conductively connected to the sensor via a sensor connecting pin component that passes through the closed portion, and the circuit substrate is conductively connected to the external device via an external connecting component led to the outside. The sensor connecting pin component that passes through the closed portion to the circuit substrate and through the setting space is connected to the circuit substrate in the filling space of the sealing material.

[0012] The external connection member is connected to the circuit substrate in a space filled with the sealing material in the circuit substrate.

[0013] An insulating coating is applied to a mounting component mounting surface of the circuit substrate on the installation space side.

[0014] An insulating coating is applied to at least the penetration portion of the component on the forming surface of the space forming member which forms the forming surface of the installation space and has a penetration portion of the component exposed in the installation space.

[0015] The effects of the utility model are as follows.

[0016] Thus, according to one embodiment of the present invention, the mounting components of the circuit substrate are located in the installation space, which can avoid contact with the sealing material and prevent stress loads from being applied to the mounting components of the circuit substrate in advance. In addition, the installation space can also be formed by the circuit substrate, which can reduce the number of parts and achieve a simple structure. Therefore, it is possible to provide a cheap pressure sensor that can be used with high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a figure which shows the pressure sensor of 1st Embodiment of this invention, and is a longitudinal cross-sectional view which shows the schematic whole structure.

[0018] Figure 2 It is a figure which shows the pressure sensor of 2nd Embodiment of this invention, and is a longitudinal cross-sectional view which shows the schematic whole structure.

[0019] Figure 3 It is a diagram showing a pressure sensor according to a third embodiment of the present invention, and is a longitudinal sectional view showing a schematic overall structure thereof.

[0020] Figure 4It is a diagram showing another form of the third embodiment and is a longitudinal sectional view showing a schematic overall structure thereof.

[0021] Figure 5 It is a figure which shows the prior art of this embodiment, and is a longitudinal sectional view which shows the schematic whole structure.

[0022] In the figure: 10—pressure sensor unit, 11—pressure sensor chip, 12—housing, 14—sealed glass, 20—waterproof shell, 24—spacer, 24b—bottom, 24d—step, 24s—side wall, 25—cover part, 26—sealing material, 30—connector part, 38—lead, 38c—covering part, 40—pin, 50—circuit substrate, 50J—mounting part, 50h1, 50h2—through hole (through hole), 61, 63—insulating coating material, 100—pressure sensor, A—external equipment, C—core wire, PR—pressure chamber, SR—setting space. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 It is a figure explaining the pressure sensor which concerns on 1st Embodiment of this invention.

[0024] <First Embodiment>

[0025] exist Figure 1 In the embodiment, the pressure sensor 100 is manufactured as follows: a pressure sensor unit 10 provided with a pressure sensor chip (sensor) 11 is installed in a refrigerant piping in the unit to measure the pressure of the refrigerant in, for example, a refrigeration cycle, and the pressure information detected by the pressure sensor chip 11 is output to an external device A which is a control device for controlling the refrigeration cycle. The pressure sensor 100 of this embodiment is configured to be able to connect the pressure sensor unit 10 having a metal waterproof housing 20 formed in a cylindrical shape to a piping for guiding a fluid such as a gas or liquid whose pressure is to be detected by connecting them using a metal joint member 30.

[0026] The waterproof housing 20 is fixed by covering one end face side of a thick cylindrical metal housing 12 that houses the sensor chip 11 of the pressure sensor unit 10 and welding, etc., and the peripheral edge of a disc-shaped metal cover 28 to which a joint component 30 is fixed is connected by welding, etc. to the other end face side of the housing 12. The joint component 30 is formed with an internal thread 30s in a manner that allows it to be threadedly fixed to a pipe or the like to be a pressure measurement object, and a fluid supplied from the pipe in the direction of arrow P is introduced into a pressure chamber PR, which is a space surrounded by the cover 28, the housing 12, and a diaphragm 32 described later, through a port 30a connected to the internal thread 30s. The outer peripheral edges of the waterproof housing 20, the housing 12, and the cover 28 are welded from the outside by TIG welding, plasma welding, laser welding, etc., and are integrated with a desired bonding strength.

[0027] The housing 12 is arranged so that the pillar 13 having the pressure sensor chip 11 at one end is located at the center of the inner tube, and a sealing glass 14 is formed to fill between the inner surface of the housing 12 and the outer surface of the pillar 13 to ensure a closed state and to fix the components penetrating the interior in a liquid-tight manner.

[0028] In the pressure sensor unit 10, a metal diaphragm 32 is fixedly bonded to the lower end surface of the housing 12. The diaphragm 32 forms an airtight pressure chamber PR on the cover 28 side and isolates the installation space of the pressure sensor chip 11 on the support 13 side in the housing 12 from the pressure chamber PR.

[0029] Furthermore, in the pressure sensor unit 10, the installation space of the pressure sensor chip 11 formed by the sealing glass 14 and the diaphragm 32 in the inner cylinder of the housing 12 is filled with a predetermined amount of silicone oil (or fluorine-based inert liquid, etc.) as a pressure transmission medium to act as a liquid seal chamber LR.

[0030] Thus, the pressure sensor chip 11 functions as a pressure sensor that detects the pressure of the fluid of the detection object introduced into the pressure chamber PR from the piping connected to the joint component 30 via the diaphragm 32 as the pressure change of the pressure transmission medium in the liquid seal chamber LR. That is, the pressure chamber PR of the present embodiment is constructed as a structure having the liquid seal chamber LR, and is made into a structure capable of detecting the pressure of the fluid of the measurement object introduced from the joint component 30 by the pressure sensor chip 11. In addition, as the pressure chamber, it is also possible to not have a liquid seal chamber, and directly load the pressure of the fluid of the measurement object on the sensor chip for measurement. In addition, the measurement object is not limited to liquids, and of course it can also be a gas such as various gases, or a mist gas containing tiny fluid particles.

[0031] The pressure sensor chip 11 is configured to be supplied with power by connecting a plurality of leads (external connection components) 38 from an external device A to pins (sensor connection pin components) 40 connected via a circuit substrate 50 described later via bonding wires 11w, and output a detection signal as pressure information. In addition, the pressure transmission medium is filled into the liquid seal chamber LR between the sealing glass 14 and the diaphragm 32 in the inner cylinder of the housing 12 via an oil filling tube 44. These pins 40 and the oil filling tube 44 are arranged in the same circle at equal intervals with the support 13 as the center, and are supported to be insulated from the housing 12 via an insulating material such as the sealing glass 14. In addition, the oil filling tube 44 is closed at one end after the pressure transmission medium is filled.

[0032] The diaphragm 32 is prevented from being damaged by external force or sudden pressure in the pressure chamber PR by joining and fixing a diaphragm protection cover 34 having a plurality of communication holes 34a to the lower end surface of the housing 12. In addition, a concave frame 16 is fixed to one end of the sealing glass 14 and a cover-shaped shielding plate 17 is installed. The frame 16 receives the pressure transmission medium between the pressure sensor chip 11 side and the diaphragm 32 side through the communication holes 17a formed in the shielding plate 17 to suppress sudden pressure changes.

[0033] The pins 40 are arranged with two power terminals, one output signal terminal, and five adjustment terminals used during assembly, and are electrically connected to the pressure sensor chip 11 via bonding wires 11 w. The pins 40 are fixedly supported on the sealing glass 14 in a manner protruding from one end surface of the housing 12 .

[0034] On one side of the housing 12, a resin spacer 24 formed in a short, substantially bottomed cylindrical shape is inserted into the waterproof case 20 from the bottom 24b side and abuts against it, and the side wall portion 24s of the spacer 24 is in close contact with the inner surface of the waterproof case 20. The spacer 24 is formed in a disk shape with the bottom 24b opened at the center side, and the pin 40 protruding from the sealing glass 14 of the housing 12 and the oil filling tube 44 can pass through the opening 24a of the bottom 24b to connect to the circuit board 50 and fill the pressure transmission medium. In this embodiment, the case where each part including the waterproof case 20 and the spacer 24 is formed in a cylindrical shape is described as an example, but it is not limited to this, and it may be a square cylinder shape. In addition, it is not limited to a bottomed cylinder shape, and of course, the bottom side thereof may be closed by a cover member.

[0035] Moreover, the circuit substrate 50 is fixed like a cover component in a manner in which the outer periphery is embedded in a step 24d formed on the opening side end of the side wall portion 24s of the spacer 24, and the mounting component 50J mounted on the circuit substrate 50 is located on the bottom 24b side (housing 12 side) of the spacer 24, closing the opening of the side wall portion 24s of the spacer 24.

[0036] That is, in the sensor unit 10, the side wall portion 24s of the spacer 24 constitutes the side wall portion, and the bottom 24b of the spacer 24 and one side of the housing 12 (sealing glass 14) in the opening 24a constitute a sealing portion fixed to one end edge side of the side wall portion 24s and sealed, and together with the circuit substrate 50, constitute a space forming member forming the installation space SR for installing the mounting component 50J. In addition, the waterproof housing 20 of the pressure sensor unit 10 is filled with a sealing material 26 such as a polyurethane resin, and the circuit substrate 50 is waterproofed from the back side of the installation space SR for the mounting component 50J and fixed. The fixing method of the circuit substrate 50 may be, of course, a part of the outer periphery or the like fixed to the step 24d of the side wall portion 24s of the spacer 24 by an adhesive or the like, or a snap-fit ​​structure in which claws are provided on the inner surface side of the outer periphery and the side wall portion 24s or the step 24d to engage by pressing or elastic engagement, etc., and is not limited to bonding, and any fixing method may be used. In addition, in the present embodiment, the spacer 24 and the circuit substrate 50 are fixed by any method, but the circuit substrate 50 may be "placed" on the opening side end of the spacer 24 without being fixed, and the setting space SR may be formed by filling the sealing material 26. That is, any structure is sufficient as long as the sealing material 26 does not leak into the setting space SR. For example, by providing the step 24d as in the present embodiment, the circuit substrate 50 and the spacer 24 will not be offset, and the leakage of the sealing material 26 can be prevented.

[0037] Among them, by locating the mounting component 50J of the circuit substrate 50 in the installation space SR formed by the housing 12, the spacer 24 and the circuit substrate 50 in the waterproof housing 20, an air layer with low thermal conductivity can be formed around the mounting component 50J of the circuit substrate 50, and the temperature change around the pressure sensor and the piping from the housing 12 side can be prevented from being rapidly transmitted to the circuit substrate 50 side. In addition, by arranging the mounting component 50J mounted on the circuit substrate 50 so as not to contact the sealing material 26, it is possible to prevent the mechanical stress caused by the contraction and expansion of the sealing material 26 accompanying the ambient temperature change from directly acting on the connecting component, the mounting component 50J, etc. As the parts weak to the mechanical stress, there are the mounting part of the mounting component 50J, the wiring pattern of the circuit substrate 50, etc., but by arranging at least the parts weak to the mechanical stress in the installation space SR so as not to contact the sealing material, it is possible to improve the resistance to the thermal stress load.

[0038] Moreover, both ends of the pin 40 penetrate both sides of the sealing glass 14 in the inner tube of the housing 12, and are conductively connected to the pressure sensor chip 11 via a bonding wire 11w at one end side serving as the liquid seal chamber LR side, and the other end side of the pin 40 corresponding to a power supply terminal and an output signal terminal penetrates through holes (through holes) 50h1 at multiple locations of the circuit substrate 50, and is conductively connected to a pad pattern not shown in the figure by welding or the like.

[0039] In addition, the lead wire 38 led out in a manner that can be connected to the external device A passes through the through hole (through hole) 50h2 of the circuit substrate 50, and the core wire C is connected to the pad pattern (not shown) by welding in the direction toward the housing 12. In addition, the connection between the pin 40 and the lead wire 38 can be carried out by not only applying molten metal such as solder, but also applying an adhesive containing a conductive material, etc. As described above, in addition to the conductive connection using soldering and a conductive adhesive, the conductive connection can also be carried out by welding (for example, spot welding using a laser, etc.), and the means of welding does not need to be particularly limited.

[0040] In addition, the circuit substrate 50 is serially interposed between the pressure sensor chip 11 and the external device A and functions as a part of the circuit structure. In this embodiment, an input-output voltage conversion adjustment circuit is mounted to adjust the different input-output voltages of the pressure sensor chip 11 and the external device A, for example, to make the input voltage DC12V or DC3.3V of the external device A become the operating voltage DC5V of the pressure sensor chip 11. Such a conversion adjustment circuit is not limited to this embodiment, and is an arbitrary conversion adjustment circuit for responding to various drive voltages and pressure detection signal signal forms such as voltage output forms of drive / output voltages different from this embodiment, current output forms such as 2-wire / 3-wire, or digital output forms.

[0041] Thus, in the pressure sensor 100 of the present embodiment, the mounting component 50J of the circuit substrate 50 connected in series and interposed between the sensor chip 11 and the external device A is accommodated in the installation space SR in the housing 20 which is filled with the sealing material 26 and sealed liquid-tightly. Therefore, in the pressure sensor 100, the mounting component 50J of the circuit substrate 50 is located in the installation space SR formed on the side of one end surface of the housing 12 between the spacer 24 and the circuit substrate 50, and the mechanical load caused by the sealing material 26 of the high-temperature resin melted during manufacturing and the thermal stress caused by the difference in expansion and contraction caused by the difference in the linear expansion coefficient of the constituent materials corresponding to the temperature change during use can be prevented from being applied as stress load to the mounting component 50J.

[0042] As a result, the pressure sensor 100 can construct the sensor unit 10 at low cost and perform high-quality pressure measurement.

[0043] <Second Embodiment>

[0044] then, Figure 2 This is a diagram illustrating a pressure sensor according to a second embodiment of the present invention. Since this embodiment is substantially the same as the above-mentioned embodiment, the same reference numerals are used for the same structures and detailed description is omitted, and only the characteristic parts are described (the same also applies to other embodiments described below).

[0045] exist Figure 2 In the pressure sensor 100, the through hole 50h2 is not formed on the circuit substrate 50, but the core wire C of the lead 38 is welded on the back side of the circuit substrate 50 relative to the mounting component 50J to connect with the external device A, and a circuit that is conductive with the mounting component 50J and the like is formed on the back side of the circuit substrate 50, and a welding pattern (not shown) connected to the core wire C of the lead 38 is formed.

[0046] In the pressure sensor 100, the end of the cover portion 38c of the lead 38 is located outside the circuit substrate 50 forming the installation space SR and is buried (molded) in the sealing material 26 to be sealed liquid-tightly. Even if the core wire C of the lead 38 is a twisted wire, it is buried in the sealing material 26 outside the installation space SR between the core wire C and the cover portion 38c. Therefore, in the pressure sensor 100, even if there is moisture that is transferred to the periphery of the core wire C of the lead 38, it is possible to prevent the moisture from entering the installation space SR.

[0047] As described above, in the pressure sensor 100 of the present embodiment, the covering portion 38 c of the lead wire 38 is peeled off outside the circuit board 50 forming the installation space SR, and the core wire C of the lead wire 38 is conductively connected without penetrating the circuit board 50 .

[0048] Therefore, in addition to the effects of the above-mentioned embodiment, the end of the covering portion 38c with a small gap between the core wire C of the lead 38 is buried in the sealing material 26 outside the setting space SR. Even if there is moisture transferred to the periphery of the core wire C, it is possible to suppress the infiltration into the setting space SR and the generation of short circuits, migration, etc. caused by condensation, thereby using it with high reliability. In addition, in this embodiment, the conductive connection portion of the pin 40 and the lead 38 exists on the surface opposite to the setting space SR across the circuit substrate 50, that is, the filling side of the sealing material 26. Therefore, the conductive connection operation of the circuit substrate 50 and the pin 40 and the lead 38 can be performed on the same plane and at the same time. Therefore, compared with the first embodiment, the productivity can be improved.

[0049] As a result, in the pressure sensor 100 , the same operational effects as those of the above-described embodiment can be obtained, and the pressure measurement can be performed with high quality while ensuring the insulation of the installation space SR.

[0050] <Third Embodiment>

[0051] then, Figure 3 It is a figure explaining the pressure sensor which concerns on 3rd Embodiment of this invention.

[0052] exist Figure 3 In the pressure sensor 100, the resin material is coated in a manner to cover the periphery of the through hole 50h1 of the pin 40 in the setting space SR of the circuit substrate 50 and the entirety including the mounting component 50J, and is coated with the insulating coating material 61. Furthermore, the resin material is coated in a manner to cover the entirety of one end surface side of the through protruding portion of the pin 40 on the sealing glass 14 side including the pillar 13 in the housing 12, and is coated with the insulating coating material 63.

[0053] According to this structure, in the pressure sensor 100, the installation space SR side of the circuit substrate 50 is covered with the insulating coating material 61, thereby ensuring improved insulation between the mounting surface of the mounting component 50J of the circuit substrate 50 and the pin 40, and the housing 12 side is also covered with the insulating coating material 63, thereby ensuring improved insulation between the housing 12 and the pin 40. In addition, the insulating coating material 61 reaching the outer edge of the circuit substrate 50 can also block the tiny gap located at the step 24d of the spacer 24 with the insulating coating material 61, thereby preventing the sealing material 26 from leaking into the installation space SR.

[0054] Thus, in the pressure sensor 100 of this embodiment, in addition to the effects of the above-mentioned embodiments, the insulation coating materials 61 and 63 can be used to cover the circuit substrate 50 side and the housing 12 side in the setting space SR and together with the mounting component 50J, the insulation of the connection part of the pin 40 can be improved, thereby enabling high-reliability and high-quality pressure measurement.

[0055] As another method of the third embodiment, Figure 4 As shown, the formation of the insulating coating material 61 can also be omitted, and there is no connection portion of the lead 38 connected to the circuit substrate 50 side in the setting space SR from the outside. In addition, the through-protruding portion of the sealing glass 14 side of the pin 40 is coated with the insulating coating material 63, so that the insulation performance equivalent to that in the above-mentioned embodiment can be ensured cheaply.

[0056] In addition, in order to further reduce the number of parts and realize a simple structure, the waterproof housing 20 is similar in shape to the cylindrical spacer 24, so the waterproof housing 20 can also have the function of a spacer supporting the circuit substrate 50. Although not shown in the figure, it can also be configured that a locking portion that is a pit or a rib protruding toward the inner surface is formed on the waterproof housing 20 at a position in the height direction that can form the installation space SR equivalent to the above-mentioned embodiments, and the circuit substrate 50 is supported by the locking portion. Even if the spacer 24 is omitted, the support portion of the circuit substrate 50 is formed by the locking portion of the waterproof housing 20, so that the installation space SR is formed between the circuit substrate 50 and the housing 12, and the mounting component 50J of the circuit substrate 50 is arranged in the space.

[0057] In addition, as another example, the housing may also function as a spacer for supporting the substrate. This is also omitted in the figure, but the housing 12 may also be configured such that the outer peripheral edge of the cylinder of the housing 12 is extended upward, that is, in the direction in which the lead wire 38 is led out, and a step 24d for supporting the circuit substrate 50 is integrally formed at the extended end, and the circuit substrate 50 is supported by the step so that the installation space SR equivalent to the above-mentioned embodiments can be formed. Even if the spacer 24 is omitted, the support portion of the circuit substrate 50 is integrally formed by extending the housing 12 upward, so that the installation space SR is formed between the circuit substrate 50 and the housing 12, and the mounting component 50J of the circuit substrate is arranged in the space.

[0058] The scope of the present invention is not limited to the exemplary embodiments shown in the drawings, but also includes all embodiments that bring about the same effect as the purpose of the present invention. In addition, the scope of the present invention is not limited to the combination of features of the present invention determined by the scope of each technical solution, but can be divided by all desired combinations of all disclosed specific features.

Claims

1. A pressure sensor, wherein a sensor for detecting the pressure of a measurement object is connected to a circuit substrate built into a housing, wherein the pressure sensor is characterized in that: The sensor is installed in the pressure chamber so as to receive the pressure of the measurement object, and the circuit board constitutes a part of a space forming member which is formed liquid-tight by filling the housing with a sealing material and forms an installation space for installing a mounting member of the circuit board.

2. The pressure sensor according to claim 1, characterized in that: The space forming component comprises: a side wall portion, which constitutes the side surface of the cylindrical shape; and a closing portion, which is located on one end edge side of the side wall portion in a manner of closing an opening of the cylindrical shape, and the circuit substrate is constructed and forms the setting space by closing the other end edge side of the side wall portion, that is, the other opening of the cylindrical shape.

3. The pressure sensor according to claim 2, characterized in that: The circuit substrate is disposed between the sensor and the external device. The circuit substrate is electrically connected to the sensor via a sensor connection pin member penetrating the sealing portion, and the circuit substrate is electrically connected to the external device via an external connection member led out to the outside. The sensor connection pin member that penetrates from the sealing portion to the circuit board and passes through the installation space is connected to the circuit board in the space filled with the sealing material.

4. The pressure sensor according to claim 3, characterized in that: The external connection member is connected to the circuit substrate in a space filled with the sealing material in the circuit substrate.

5. The pressure sensor according to claim 1, characterized in that: An insulating coating is applied to a mounting component mounting surface of the circuit substrate on the installation space side.

6. The pressure sensor according to claim 1, characterized in that: An insulating coating is applied to at least the penetration portion of the component on the forming surface of the space forming member which forms the forming surface of the installation space and has a penetration portion of the component exposed in the installation space.

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