Pressure sensor and method for fabricating pressure sensor

Abstract

To provide an inexpensive pressure sensor that can achieve a structure securing stress reduction and insulating property for an internally installed circuit board and can achieve high-quality pressure measurement.SOLUTION: A method for fabricating a pressure sensor 100 in which a sensor chip 11 for detecting pressure is connected to a circuit board 50 in a case 20, includes: an assembly step of arranging the sensor chip in a pressure chamber PR of a housing 12 and connecting it to the circuit board; a storage step of inserting the sensor, the circuit board and the housing into the case having a cylindrical shape; a space formation step of arranging the case in an elected state so that the housing is positioned at an upper part and the circuit board is positioned blow the housing, and filling the other end side opening side of a lower part of the case with a sealing material 26 to liquid-tightly close the other end side opening side, and forming an installation space SR for the circuit board between the housing on one end side opening side and the sealing material on the other end side opening side of the case; and a closing step of liquid-tightly closing the one end side opening side of the case.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pressure sensor that is liquid-tightly molded with resin and a method for manufacturing the same. [Background technology]

[0002] 2. Description of the Related Art Various sensors for detecting pressure, temperature, etc. are fixed in the vicinity of a measurement object and are used to send a detection signal to a measuring instrument, etc., and are often used either built into the measuring instrument or attached externally.

[0003] These types of sensors are incorporated into sensor units so that they can be installed in locations exposed to the same environment as the object to be measured. For example, a circuit board may be installed inside the sensor chip when it is necessary to change the electrical characteristics input and output to the sensor chip (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6633597 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the pressure sensor described in Patent Document 1, as shown in FIG. 9, a circuit board 1431 connected to a sensor chip 1121 in a housing 1124 is contained in a case 1135, and the case 1135 is filled with a sealing material 1136 such as a resin material to provide a liquid-tight seal.

[0006] In such a structure, since there is a difference in the linear expansion coefficient of components such as the circuit board 1431, the case 1135, and the sealing material 1136, when a temperature difference occurs inside and outside the object to be measured, a stress corresponding to the temperature difference may occur. This stress may become a load on the circuit board 1431 itself and the components mounted on the circuit board 1431. In addition, since various electric and electronic components are mounted on the circuit board 1431 in such a pressure sensor, it is necessary to ensure insulation around the circuit board 1431. In addition, there is a constant demand for cost reduction in devices such as pressure sensors.

[0007] Therefore, an object of the present invention is to provide an inexpensive pressure sensor that can reduce the stress applied to the internal circuit board, realizes a structure that ensures insulation, and can perform high-quality pressure measurements. [Means for solving the problem]

[0008] One aspect of the invention of a method for manufacturing a pressure sensor that solves the above-mentioned problems is a method for manufacturing a pressure sensor in which a sensor for detecting the pressure of an object to be measured is connected to a circuit board that is mounted inside a case, the method comprising the steps of: arranging the sensor in a pressure chamber provided in a housing so as to receive the pressure of the object to be measured, and connecting the circuit board to the sensor; an accommodating step of inserting the housing together with the sensor and the circuit board into the cylindrical case that is open at both ends, so that the housing is positioned at the top and the circuit board is positioned below the housing, and filling the other end opening located at the bottom of the case with a sealant to liquid-tightly close the other end opening of the case, thereby forming an installation space capable of accommodating the circuit board between the housing on the one end opening side of the case and the sealant on the other end opening side; and a closing step of liquid-tightly closing the one end opening side of the case where the housing is located.

[0009] One aspect of the invention for a pressure sensor that solves the above-mentioned problems is a pressure sensor that is manufactured by the above-mentioned pressure sensor manufacturing method, and in which a sensor that detects the pressure of the object to be measured is connected to a circuit board that is mounted inside a case, the sensor is disposed in a pressure chamber provided in a housing so as to receive the pressure of the object to be measured, the circuit board is disposed in an installation space that is formed liquid-tight, the case is formed in a cylindrical shape that opens on both ends, and the installation space is formed such that the housing is installed so as to liquid-tightly close one end opening of the case, and a filler is filled on the other end opening side so as to liquid-tightly close the other end opening of the case, thereby liquid-tightly closing both ends of the case. Effect of the Invention

[0010] Thus, according to one aspect of the present invention, the mounted components of the circuit board are positioned within the installation space, and can be prevented from coming into contact with the sealing material, thereby preventing stress load from being applied to the mounted components of the circuit board. Furthermore, the circuit board is installed in the installation space that is liquid-tightly closed, and thus the mounted components are mounted with improved insulation resistance. Furthermore, the installation space can be formed by filling the sealing material, and the number of components can be reduced to achieve a simple structure. Therefore, an inexpensive pressure sensor that can be used with high reliability can be provided. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a pressure sensor according to a first embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration thereof. [Diagram 2] FIG. 2 is a diagram for explaining an assembly step of the method for producing the pressure sensor according to the first embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration at that step. [Diagram 3] FIG. 3 is a diagram for explaining an assembly step of the method for producing the pressure sensor according to the first embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration in the state following FIG. 2 at that step. [Figure 4]FIG. 4 is a diagram for explaining the accommodation step of the method for producing the pressure sensor according to the first embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration at that step. [Diagram 5] FIG. 5 is a diagram for explaining a space forming step in the method for producing the pressure sensor according to the first embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration at that step. [Figure 6] FIG. 6 is a diagram for explaining the closing step of the method for producing the pressure sensor according to the first embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration at that step. [Figure 7] FIG. 7 is a diagram for explaining one step of the method for producing a pressure sensor according to the second embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration at that step. [Figure 8] FIG. 8 is a diagram for explaining one step of the method for producing a pressure sensor according to the third embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration at that step. [Figure 9] FIG. 9 is a diagram showing the prior art of this embodiment, and is a vertical sectional view showing a schematic overall configuration thereof. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Figures 1 to 8 are diagrams illustrating a pressure sensor produced by a production method according to a first embodiment of the present invention.

[0013] <First embodiment of pressure sensor>

[0014] In Fig. 1, the pressure sensor 100 is fabricated so that a pressure sensor unit 10 having a pressure sensor chip (sensor) 11 installed therein is attached to a refrigerant pipe in a unit to measure the pressure of the refrigerant in a refrigeration cycle, for example, and 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 constructed so that the pressure sensor unit 10 having a cylindrical waterproof case 20 can be connected to a pipe to be measured, through which a fluid such as a gas or liquid whose pressure is to be detected is introduced, by connecting the pressure sensor unit 10 with a metallic joint member 30. Here, in this embodiment, a case where each part including the waterproof case 20 and a housing 12 described later is formed into a cylindrical shape is described as an example, but the present invention is not limited to this, and it goes without saying that a square tube shape or the like may be used.

[0015] Here, the waterproof case 20 is provided so as to cover one end surface side of a thick cylindrical metal housing 12 that houses the sensor chip 11 of the pressure sensor unit 10, and the peripheral portion of a disk-shaped metal cap 28 to which a joint member 30 is fixed is connected to the other end surface side of the housing 12 by welding or the like. This joint member 30 is formed with a female thread 30s so as to be screwed to a pipe or the like for pressure measurement, and realizes that 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 cap 28, the housing 12, and a diaphragm 32 described later, through a port 30a communicating with the female thread 30s. Here, the housing 12 and the cap 28 are integrated with a desired joint strength by welding the outer peripheral portions from the outside by TIG welding, plasma welding, laser welding, or the like.

[0016] The housing 12 is arranged so that the support 13, on one end of which the pressure sensor chip 11 is installed, is located at the center of the inner cylinder, and hermetic glass 14 is formed by filling the space between the inner surface of the housing 12 and the outer surface of the support 13 to ensure a closed state while fixing the members that pass through the interior in a liquid-tight manner.

[0017] In this pressure sensor unit 10, a metal diaphragm 32 is bonded and fixed to the bottom end surface of the housing 12. The diaphragm 32 forms an airtight pressure chamber PR on the cap 28 side, while isolating the installation space of the pressure sensor chip 11 on the support 13 side in the housing 12 from the pressure chamber PR.

[0018] In this pressure sensor unit 10, the installation space for the pressure sensor chip 11, which is formed by the hermetic glass 14 and the diaphragm 32 within the inner tube of the housing 12, is filled with, for example, a predetermined amount of silicone oil (or a fluorine-based inert liquid, etc.) as a pressure transmission medium, so as to function as a liquid-sealed chamber LR.

[0019] As a result, the pressure sensor chip 11 functions as a pressure sensor that detects the pressure of the fluid to be detected, introduced into the pressure chamber PR from the piping connected to the joint member 30, as a pressure fluctuation of the pressure transmission medium in the liquid-sealed chamber LR via the diaphragm 32. That is, the pressure chamber PR in this embodiment is constructed in a structure including a liquid-sealed chamber LR, and is fabricated in a structure that enables the pressure sensor chip 11 to detect the pressure of the fluid to be measured introduced from the joint member 30. Note that the pressure chamber may not include a liquid-sealed chamber, and the pressure of the fluid to be measured may be directly applied to the sensor chip to be measured, and it goes without saying that the measurement target is not limited to liquid, but may be gas such as various gases or mist-like gas containing fine fluid particles.

[0020] Here, the pressure sensor chip 11 is installed so that it is supplied with power by electrically connecting lead pins (sensor connection pin members) 40 connected to a circuit board 50 (described later) via bonding wires 11w, respectively, from a plurality of lead wires (external connection members) 38 from the external device A, and outputs a detection signal as pressure information. In addition, the liquid-sealed chamber LR between the hermetic glass 14 and the diaphragm 32 in the inner cylinder of the housing 12 is filled with a pressure transmission medium via an oil filling pipe 44. These lead pins 40 and the oil filling pipe 44 are aligned at equal intervals in a circle centered on the support 13, and are supported insulated from the housing 12 via an insulator such as the hermetic glass 14. One end of the oil filling pipe 44 is closed after filling with the pressure transmission medium.

[0021] Here, the diaphragm 32 is prevented from being damaged by external forces or sudden pressures applied to the pressure chamber PR by a diaphragm protective cover 34 having a plurality of communication holes 34a bonded and fixed to the lower end surface of the housing 12. Also, a concave frame 16 is fixed to one end side of the hermetic glass 14 and a lid-like shield plate 17 is attached to the frame 16, and the frame 16 contains a pressure transmission medium between the pressure sensor chip 11 side and the diaphragm 32 side through the communication holes 17a formed in the shield plate 17 and suppressing sudden pressure fluctuations.

[0022] The lead pins 40 include two power supply 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 11w. These lead pins 40 are fixedly supported by the hermetic glass 14 so as to protrude from one end face side of the housing 12.

[0023] The pressure sensor unit 10 is constructed by filling and sealing the other end opening side of the waterproof case 20, which is separated from the housing 12, with a sealant 26 such as a urethane resin in a liquid-tight manner on one end surface side of the housing 12, thereby providing an installation space SR for the circuit board 50 to which the lead pins 40 and the lead wires 38 are connected. The waterproof case 20 of the pressure sensor unit 10 does not require the installation of a plate-like member or the like for forming and securing a space, and the installation space SR for the circuit board 50 is sealed while being waterproofed, by the sealant 26 such as a urethane resin being fixed in a liquid-tight manner, and the circuit board 50 is positioned and supported by being soldered to the lead pins 40 and the core wires C of the lead wires 38.

[0024] In this structure, the circuit board 50 is supported in the vertical direction by the soldered lead wires 38 and lead pins 40 and is held in the middle (hollow) of the installation space SR, and even if the sealing material 26, the circuit board 50, etc. contract or expand due to changes in the ambient temperature, the circuit board 50 is not in contact with the sealing material 26 or the housing 12, etc., and it is possible to prevent mechanical stress from acting on the mounted components 50J and especially on their soldered parts. Furthermore, even if temperature is transmitted from the lead pins 40, etc. connected to the circuit board 50, it is possible to prevent the supporting lead wires 38 and lead pins 40 from being slightly deformed and the stress itself from being applied.

[0025] Furthermore, by placing the circuit board 50 in the installation space SR inside the waterproof case 20, an air layer with low thermal conductivity can be formed around the circuit board 50, preventing the temperature change from around the pressure sensor or from the piping from being suddenly transmitted to the circuit board 50, i.e., preventing a so-called heat shock.

[0026] Meanwhile, both ends of the lead pin 40 penetrate both sides of the hermetic glass 14 inside the inner tube of the housing 12, and one end thereof which is on the liquid-sealed chamber LR side is conductively connected to the pressure sensor chip 11 via a bonding wire 11w, while the other end of the lead pin 40 which corresponds to the power supply terminal and the output signal terminal penetrates through multiple through holes (through holes) 50h1 in the circuit board 50 and is conductively connected by soldering or the like to a land pattern not shown.

[0027] Furthermore, the multiple lead wires 38 drawn out so as to be connectable to the external device A penetrate the sealing material 26 at the open end side of the waterproof case 20, and then penetrate the through hole 50h2 of the circuit board 50 toward the housing 12, and the core wires C are soldered or otherwise connected to a land pattern (not shown) in the direction toward the housing 12. Needless to say, the connection of the lead pins 40 and the lead wires 38 may be made not only by molten metal such as solder, but also by applying, for example, an adhesive containing a conductive material. Furthermore, as described above, in addition to the conductive connection by soldering or conductive adhesive, the conductive connection may be made by welding (for example, spot welding with a laser or the like), and there is no need to limit the means of conductive connection in particular.

[0028] Here, the circuit board 50 is disposed in the installation space SR in the waterproof case 20, and the installation space SR is formed to be liquid-tight and of a desired dimension that sufficiently secures the distance of the circuit board 50 from the electrically conductive lead pins 40 and the housing 12. That is, since the installation space SR is an air atmosphere, it is difficult to maintain the insulation with high reliability and low cost compared to embedding (molding) with the sealing material 26, but it is provided to improve the insulation resistance between the housing 12 and the circuit board 50 and the mounted component 50J by sufficiently securing the distance between them. The housing 12 is made of metal together with the joint member 30 and the piping to be connected, and therefore has the same potential as these. When noise or static electricity from the outside is transmitted to the housing through the metal parts, the housing 12 and the circuit board 50 are separated from each other, so that the adverse effects of noise, static electricity, etc. on the circuit board 50 and the sensor chip 11 can be reduced by isolating the housing 12 from the circuit board 50.

[0029] The circuit board 50 is arranged in series between the pressure sensor chip 11 and the external device A to function as a part of the circuit configuration, and in this embodiment, an input / output voltage conversion adjustment circuit is mounted thereon to adjust different input / output voltages between the pressure sensor chip 11 and the external device A, for example, to convert the input voltage DC12V or DC3.3V of the external device A to the operating voltage DC5V of the pressure sensor chip 11. This type of conversion adjustment circuit is not limited to this embodiment, but may be any conversion adjustment circuit for dealing with various driving voltages and signal formats of pressure detection signals, such as a voltage output format of driving / output voltages different from this embodiment, a current output format such as a two-wire type / three-wire type, or a digital output format. These conversion adjustment circuits are configured by mounting a plurality of electronic components (not shown).

[0030] <First embodiment of the method for producing a pressure sensor> The pressure sensor 100 is produced by the production method shown in FIGS. 2 to 8, in which an installation space SR for the circuit board 50 is formed inside the waterproof case 20. As shown in FIG.

[0031] <Assembly steps> First, as shown in FIG. 2, an assembly step is performed in which the above-mentioned components to be housed in the waterproof case 20 are prepared, and various operations such as connection and joining are performed to assemble the base sensor unit 10.

[0032] In this assembly step, the lead pins 40 and the oil filling pipe 44 are positioned in the housing 12 and filled with molten glass to form the hermetic glass 14 and fix the position, and then the sensor chip 11 to be fixed to the support 13 is connected to the lead pins 40 via the bonding wires 11w, and the components around the sensor such as the diaphragm 32 are attached to the housing 12 to form a space to be the pressure chamber PR having the liquid sealed chamber LR. After this, the lead pins 40 and the lead wires 38 are soldered to the mounted circuit board 50 of the assembly in which the cap 28 is joined together with the joint member 30 to the housing 12, and the liquid sealed chamber LR is made functional by filling it with a pressure transmission medium from the oil filling pipe 44, and then one end of the oil filling pipe 44 is closed to complete the assembly.

[0033] <Containment Steps> Next, as shown in the figure, a housing step is performed in which the assembled sensor unit 10 is housed in a waterproof case 20 having a generally cylindrical shape with openings on both ends.

[0034] In this accommodation step, the lead wires 38 are inserted into the waterproof case 20 from the side where they are inserted, and up to the housing 12, so that the housing 12 is positioned at one end opening side of the waterproof case 20, the lead wires 38 are pulled out from the other end opening of the waterproof case 20, and the circuit board 50 is positioned midway in the cylindrical axial direction of the waterproof case 20.

[0035] Here, the waterproof case 20 is formed in an approximately cylindrical shape with two stages of an end edge opening 21 and a next end edge opening 22 on one end opening side, each having an inner circumferential surface larger than the outer diameter of the housing 12, and with an other end edge opening 23 on the other end opening side opposite the position adjacent to the next end edge opening 22, which has an inner circumferential surface equal to the outer diameter of the housing 12 and into which the housing 12 can be fitted.

[0036] With this structure, when the sensor unit 10 is inserted into the waterproof case 20 from the lead wire 38 side, the waterproof case 20 can be positioned in such a way that the outer periphery of one end face side of the housing 12 is placed (contacted) on the step 25 of the next edge opening 22 and the other edge opening 23 while the joint member 30 is in an upright position facing upward (to the top) and the lead wire 38 facing downward (to the bottom), as shown in Fig. 2. In this state, the waterproof case 20 is positioned by the step 25 in such a way that a gap is secured between the outer periphery of the housing 12 and the inner periphery of the extreme edge opening 21, and the outer periphery of the housing 12 is in contact with the inner periphery of the next edge opening 22, and a gap (communication passage) G is secured between the inner periphery of the waterproof case 20 and the outer periphery of the housing 12 on the radial opposite side of the step 25, such that, for example, a tubular nozzle (not shown) that dispenses the sealant 26 (molten resin material R) can be inserted. In this embodiment, the gap G into which the nozzle can be inserted is formed by the difference in outer diameter between the waterproof case 20 and the housing 12. However, the present invention is not limited to this. For example, it is possible to form a through hole communicating with the outside in the cap 28 and the housing 12 as a communication passage. In addition, the waterproof case 20 is formed by stacking a plurality of cylindrical shapes, but the shape is not limited to this. For example, the waterproof case 20 may have a structure in which a plurality of ribs are formed along the axial direction on the inside of the waterproof case 20, and the ribs have a step portion on which the outer periphery of the housing 12 is placed on one end face side. The ribs can provide a gap large enough to form the communication passage G between the outer periphery of the housing 12 and the inner periphery of the waterproof case 20. Alternatively, the communication passage G may be formed in a pipe shape, that is, the shape is required to be such that the communication passage G can be formed between the inner surface of the waterproof case 20 and the outer periphery of the housing 12 while engaging with the waterproof case 20 at a certain position in the axial direction when the housing 12 is accommodated inside the waterproof case 20.

[0037] <Space formation step> Next, as shown in Figures 3 and 4, a space forming step is performed in which the other end opening side of the waterproof case 20 is liquid-tightly sealed, for example, with a sealing material 26 (molten resin material R), to form an installation space SR capable of accommodating a circuit board 50 between the housing 12 on the one end opening side of the waterproof case 20.

[0038] In this space forming step, first, as shown in FIG. 3, a blocking member (opening closing member) 27 is placed to block at least the other end opening side of the waterproof case 20 to such an extent that the molten resin material R of the sealant 26 does not leak when filling the opening, with the lead wire 38 penetrating the through hole 27h. In one example, the blocking member 27 is an elastic member such as rubber or urethane resin, and is preferably made of a material that has good adhesion and bonding properties with the sealant 26. By using such a material, when the lead wire 38 is inserted through the through hole 27h, it elastically adheres to the coating of the lead wire 38, and when the lead wire 38 is fitted into the waterproof case 20, it elastically adheres to the inner surface of the waterproof case 20, and also has good adhesion to the sealant 26, so that the through hole 27h of the lead wire 38 and the gap when the lead wire 38 is assembled into the waterproof case 20 can be more reliably sealed. In addition, the lead wire 38 pull-out portion can flexibly respond to the bending load at the base of the lead wire 38, and the risk of cracking, disconnection, etc. of the coating can be reduced by reducing the load. 4, the tubular nozzle is inserted through the gap G between the waterproof case 20 in an upright state and the housing 12, and a predetermined amount of the molten resin material R of the sealant 26 is discharged and filled on the upper surface side of the blocking member 27 to liquid-tightly block the other end opening side of the waterproof case 20, thereby forming an installation space SR capable of accommodating the circuit board 50 between the sealant 26 and one end surface side of the housing 12. Here, in this embodiment, a communication passage is formed that connects the gap G, which is open so that the nozzle can be inserted, with the outside, but in addition to inserting the nozzle, if the waterproof case 20 has a large diameter so as not to come into contact with the circuit board 50, the molten resin material R may be dripped onto the inner surface of the waterproof case 20 from the gap G that communicates with the outside to liquid-tightly block the other end opening side. Further, although the other end of the waterproof case 20 is closed using the closing member 27 here, the present invention is not limited to this. For example, a closing member made of a material to which the sealant 26 does not adhere, or which can be easily peeled off even if it does adhere, such as PTFE or silicone rubber, may be pressed against the end face of the other end of the waterproof case 20, or the other end may be covered in a cap shape to temporarily close the other end, and the sealant 26 may be filled and hardened, and then the closing member may be removed, thereby closing the opening side of the other end of the waterproof case 20 with the hardened sealant 26 itself.By closing the opening at the other end of the waterproof case 20 in this manner using a jig or tool, it is possible to close the opening without using the closing member 27, thereby reducing the number of parts.

[0039] <Closing step> Next, as shown in Figures 5 and 6, a sealing step is performed on the opening side of one end of the waterproof case 20, in which, for example, a molten resin material R similar to the sealing material 26 is ejected to liquid-tightly seal the gap G between the housing 12 and the outer peripheral edge of the cap 28.

[0040] In this closing step, first, as shown in Fig. 5, a closing member (passage closing member) 37 is placed to close at least one end opening side of the waterproof case 20 to such an extent that the molten resin material R of the sealant 36 does not leak when it is discharged and filled. After this, as shown in Fig. 6, a predetermined amount of the molten resin material R of the sealant 36 is discharged and applied to the upper surface side of the closing member 37 that covers the gap G between the housing 12 and the outer periphery of the cap 28 located on the one end opening side (upper surface side) of the waterproof case 20 in the standing state, thereby liquid-tightly closing the one end opening side of the waterproof case 20 as well, thereby liquid-tightly closing the installation space SR formed between the sealant 26 and the one end surface side of the housing 12 to accommodate the circuit board 50. The closing member 37 here can be more reliably closed by using a material that has excellent adhesion and bonding properties with the sealant 36 and also has excellent elastic deformation because it fills the gap. For example, the cap 28, the outer peripheral surface of the housing 12 and the inner peripheral portion of the extreme edge opening 21 of the waterproof case 20 may be sealed using a commercially available rubber packing such as an O-ring, butyl rubber, sealing material, etc., either alone or in combination, and then closed by filling with sealing material 36.

[0041] In this manner, in the pressure sensor 100 and the manufacturing method thereof according to the present embodiment, the sealant 26 is filled in the other end opening side of the waterproof case 20 to close (seal) it liquid-tightly, and the one end opening side where the housing 12 is located is also liquid-tightly closed, thereby forming an installation space SR for the circuit board 50 to be connected in series between the sensor chip 11 and the external device A without using a special plate material or cylindrical material. Therefore, in the pressure sensor 100, the installation space SR can be formed on one end surface side of the housing 12 by discharging the molten high-temperature resin from a nozzle to fill the sealants 26, 36 so as not to come into direct contact during manufacturing, and since the circuit board 50 is accommodated in the installation space SR, which is a space surrounded by the housing 12, the waterproof case 20, and the sealant 26, it is possible to prevent a mechanical load due to direct contact during manufacturing and a stress load caused by a difference in linear expansion coefficient due to a temperature change during use from being applied to the board itself or the mounted component 50J. In addition, since an air layer with low thermal conductivity is interposed between the housing 12 and the circuit board 50 and the mounted components 50J, it is possible to suppress heat shock caused by a sudden change in temperature around the pressure sensor or from the piping being transmitted to the circuit board 50.

[0042] Furthermore, in this pressure sensor 100, an air atmosphere is interposed within the space surrounded by the housing 12 and the waterproof case 20 in the installation space SR in which the circuit board 50 is installed, thereby improving the insulation resistance between the housing 12 and the circuit board 50 and the mounted components 50J.

[0043] Furthermore, in both cases, the sealing material 26, 36 is filled from one direction with the other end opening of the waterproof case 20 facing downward and the one end opening facing upward, and since the pressure sensor 100 does not need to be turned upside down during the two sealing material filling processes, the process can be easily automated.

[0044] As a result, the pressure sensor 100 ensures the insulation of the circuit board 50 and can perform high-quality pressure measurement.

[0045] <Second embodiment> 7 is a diagram illustrating a pressure sensor fabricated by a fabrication method according to a second embodiment of the present invention. Since this embodiment is configured in substantially the same manner as the above-described embodiment, the same components are given the same reference numerals, detailed descriptions are omitted, and only the characteristic parts are described (the same applies to the other embodiments described below).

[0046] In FIG. 7, the pressure sensor 100 is configured in a manner substantially similar to the first embodiment described above. In this pressure sensor 100, a resin material is applied so as to cover the entire area including the lead pins 40 and the areas around the through holes 50h1 and 50h2 of the lead wires 38 and the mounted components 50J within the installation space SR of the circuit board 50, and thus a coating is performed with an insulating coating material 61.

[0047] Due to this structure, in the pressure sensor 100, the entire periphery of the circuit board 50 in the installation space SR is covered with the insulating coating material 61, thereby improving and ensuring insulation between the mounting surface of the mounted component 50J on the circuit board 50 and the lead pins 40 and lead wires 38, and also ensuring improved insulation between the waterproof case 20 due to the insulating coating material 61 reaching the outer edge of the circuit board 50.

[0048] Although not shown in the drawings, this pressure sensor 100 is also manufactured by the manufacturing method described in the above embodiment, and in particular, the insulating coating material 61 is formed around the circuit board 50 in the assembly step.

[0049] <Assembly steps> As in the above embodiment, the above-mentioned components to be housed in the waterproof case 20 are prepared, and various operations such as connection and joining are carried out to assemble the base sensor unit 10 in an assembly step.

[0050] In this assembly step, first, the pressure chamber PR is formed by attaching various parts such as the support 13, sensor chip 11, lead pins 40 and diaphragm 32 to the housing 12, and then the lead pins 40 and oil filling pipe 44 are positioned and fixed within the housing 12 using the hermetic glass 14.

[0051] After this, the coupling member 30 and the cap 28 are joined to the housing 12, and the lead pins 40 and the lead wires 38 are soldered to the circuit board 50 to establish a conductive connection, and a liquid-sealed chamber LR is formed in which the pressure transmission medium is filled from the oil filling pipe 44 (including closing one end of the oil filling pipe 44). After this, the entire outer surface of the circuit board 50 carrying the mounted component 50J is coated with an insulating coating material 61.

[0052] Thus, in the pressure sensor 100 of this embodiment, in addition to the effects of the above-mentioned embodiments, the entire circuit board 50 in the installation space SR is covered with the insulating coating material 61, which improves the insulation of the connection points of the lead pins 40 and the lead wires 38 together with the mounted components 50J, thereby enabling reliable and high-quality pressure measurement. In the first embodiment, it was necessary to separate the circuit board 50 from the housing 12 in order to ensure an insulation distance between them. However, in this embodiment, by covering the entire circuit board 50 with the insulating coating material 61, the insulation distance can be made shorter than when there is only an air layer, i.e., the height of the installation space SR can be kept low.

[0053] <Third embodiment> Next, FIG. 8 is a diagram illustrating a pressure sensor according to a third embodiment of the present invention. 8, the pressure sensor 100 is configured substantially similarly to the first embodiment, and in this pressure sensor 100, instead of the core wire C of the lead wire 38 being directly conductively connected to the circuit board 50, the core wire C of the lead wire 38 is soldered to one end of a contact pin (external connection pin member) 65 and extended. The other end of the contact pin 65 penetrates the through hole 50h2 of the circuit board 50 in the direction toward the housing 12 and is conductively connected by soldering or the like, and the connection point of the contact pin 65 and the core wire C of the lead wire 38 is adjusted so as to be embedded and molded in the sealant 26 that liquid-tightly closes the other end opening side of the waterproof case 20.

[0054] For this reason, the lead wire 38 that is pulled out so as to be connectable to the external device A has its connection point with the contact pin 65 embedded in the sealing material 26 that forms the installation space SR, and the end of the exposed coating 38c around the core wire C is liquid-tightly sealed.

[0055] Although not shown in the figures, this pressure sensor 100 is also manufactured using the manufacturing method described in the above embodiment, and in particular, in the assembly step, accommodation step and space formation step, the connection points of the lead wires 38 and the contact pins 65 are embedded in the sealing material 26 on the other end opening side of the waterproof case 20.

[0056] <Assembly steps> As in the above embodiment, the above-mentioned components to be housed in the waterproof case 20 are prepared, and various operations such as connection and joining are carried out to assemble the base sensor unit 10 in an assembly step.

[0057] In this assembly step, first, the pressure chamber PR is formed by attaching various parts such as the support 13, sensor chip 11, lead pins 40 and diaphragm 32 to the housing 12, and then the lead pins 40 and oil filling pipe 44 are positioned and fixed within the housing 12 using the hermetic glass 14.

[0058] This is followed by the joining of the joint member 30 and the cap 28 to the housing 12, the conductive connection of the lead pins 40, the contact pins 65 and the lead wires 38 to the circuit board 50 by soldering, and the formation of a liquid-sealed chamber LR into which the pressure transmission medium is filled from the oil filling pipe 44. In this case, when soldering the lead wires 38 and the contact pins 65, either the operation of connecting the core wire C of the lead wire 38 to one end of the contact pin 65 or the operation of connecting the other end of the contact pin 65 to the circuit board 50 may be performed first, or they may be performed simultaneously.

[0059] <Containment Steps> Next, as in the above embodiment, a substantially cylindrical waterproof case 20 with openings on both ends is prepared, and a housing step is performed in which the assembled sensor unit 10 is housed in the waterproof case 20.

[0060] In this accommodation step, the lead wire 38 with the contact pin 65 is inserted into the waterproof case 20 from the side thereof, and the housing 12 is accommodated therein, and the outer periphery of one end face of the housing 12 is placed on the step 25 of the waterproof case 20 to position it.

[0061] <Space formation step> Next, similarly to the above embodiment, a space forming step is performed in which the other end opening of the waterproof case 20 is liquid-tightly sealed with the sealant 26 to form an installation space SR capable of accommodating the circuit board 50 between the housing 12 and the waterproof case 20 .

[0062] In this space forming step, first, the blocking member 27, through which the lead wire 38 passes through the through hole 27h, is placed (covered) on the other end opening side of the waterproof case 20 to block the sealing material 26 (molten resin material R) to an extent that it does not leak when filled. After this, the tubular nozzle is inserted from the gap G between the waterproof case 20 in an upright state and the housing 12, and a predetermined amount of the molten resin material R of the sealing material 26 is discharged and filled onto the upper surface side of the blocking member 27 until the connection portion between the lead wire 38 and the contact pin 65 is filled, and the end of the coating 38c exposing the periphery of the core wire C of the lead wire 38 is molded and liquid-tightly sealed, thereby forming an installation space SR capable of accommodating the circuit board 50 between the sealing material 26 and one end surface side of the housing 12.

[0063] Thus, in the pressure sensor 100 of this embodiment, the connection portion between the contact pin 65 connected to the circuit board 50 and the lead wire 38 is embedded in the sealing material 26 that forms the installation space SR, and the end of the coating 38c that exposes the core wire C of the lead wire 38 is liquid-tightly molded in the sealing material 26. Therefore, even if the core wire C of the lead wire 38 is a twisted wire, the space between the coating 38c can be embedded in the sealing material 26 that forms the installation space SR, and even if there is moisture that has been transferred around the core wire C, it can be prevented in advance from infiltrating into the circuit board 50 side in the installation space SR.

[0064] As a result, the pressure sensor 100 can achieve the same effects as the above-described embodiment, and the insulation of the circuit board 50 is ensured, enabling high-quality pressure measurement.

[0065] The scope of the present invention is not limited to the exemplary embodiments shown and described, but includes all embodiments that achieve equivalent effects to the object of the present invention. Moreover, the scope of the present invention is not limited to the combination of inventive features specified in each claim, but may be defined by any desired combination of each and every particular feature disclosed. [Explanation of symbols]

[0066] 10...Pressure sensor unit 11...Pressure sensor chip 12. Housing 20...Waterproof case 25...Step 26, 36...Sealing material 27, 37...Blocking member 28...Cap 30...Joint member 38...Lead wire 38c……Covering 40...Lead pin 50...Circuit board 50J...Mounted parts 61...Insulating coating material 65...Contact pin 100...Pressure sensor A……External device C...Core wire G...gap R……Molten resin material SR……Installation space

Claims

1. A method for manufacturing a pressure sensor in which a sensor for detecting a pressure to be measured is connected to a circuit board that is installed inside a case, comprising the steps of: an assembly step of disposing the sensor in a pressure chamber of a housing so as to receive a pressure to be measured, and connecting the circuit board to the sensor; an accommodating step of inserting and accommodating the housing together with the sensor and the circuit board into the cylindrical case having openings at both ends so that the housing is positioned at one end opening side of the case; a space forming step of standing the case upright so that the housing is located at the top and the circuit board is located below the housing, filling the other end opening side located at the bottom of the case with a sealant to liquid-tightly close the other end opening side of the case, and forming an installation space capable of accommodating the circuit board between the housing on the one end opening side of the case and the sealant on the other end opening side; a closing step of liquid-tightly closing an opening side of one end of the case where the housing is located; A method for manufacturing a pressure sensor comprising the steps of:

2. In the accommodating step, a communication passage is formed on the housing side, the communication passage leading from the outside of the housing to the inside of the case, In the space forming step, the sealant is filled into the other end opening of the case located at the lower part through the communication passage on the housing side located at the upper part, thereby liquid-tightly closing the other end opening of the case.

2. A method for producing a pressure sensor according to claim 1.

3. 3. The method for manufacturing a pressure sensor according to claim 2, wherein the communication passage is formed by manufacturing the housing and the case to dimensions that generate a gap between an outer peripheral surface of the housing and an inner peripheral surface of the case.

4. The method for manufacturing a pressure sensor as described in claim 1, characterized in that in the space forming step, an opening closure member is attached to close the other end opening of the case located at the bottom so that the sealing material made of resin can be filled into the other end opening of the case.

5. 3. The method for producing a pressure sensor according to claim 2, wherein in the closing step, the communication passage on the housing side located at the upper part is filled with a sealing material made of a resin material to close the communication passage liquid-tightly.

6. 6. The method for producing a pressure sensor according to claim 5, wherein in the closing step, a passage closing member is attached to close the communication passage so that the sealing material can be formed in the communication passage.

7. the circuit board is disposed between the sensor and an external device, In the assembly step, an external connection member for connecting to the external device is connected to the circuit board, In the accommodating step, the external connection member is pulled out from the other end opening side of the case, In the space forming step, a sealant is filled into the other end opening of the case located at the lower portion, thereby liquid-tightly closing the other end opening of the case in a state in which the external connection member passes from inside the case to the outside.

2. A method for producing a pressure sensor according to claim 1.

8. In the assembly step, an external connection member for connecting to the external device is connected to the circuit board via an external connection pin member, In the space forming step, a sealant is filled into the other end opening side of the case located at the lower part, and the connection points of the external connection member and the external connection pin member are positioned within the sealant filled into the other end opening side of the case located at the lower part, thereby liquid-tightly closing the other end opening side of the case.

8. The method for producing a pressure sensor according to claim 7.

9. 2. The method for producing a pressure sensor according to claim 1, wherein the assembling step includes providing an insulating coating to cover an outer surface of the circuit board.

10. A pressure sensor manufactured by the method for manufacturing a pressure sensor according to any one of claims 1 to 9, in which a sensor for detecting a pressure to be measured is connected to a circuit board that is installed inside a case, the sensor is disposed in a pressure chamber of the housing so as to receive the pressure of the object to be measured, and the circuit board is disposed in an installation space formed liquid-tight; The case is formed in a cylindrical shape with both ends open, The installation space is formed by liquid-tightly closing both ends of the case by the housing being installed so as to liquid-tightly close one end opening of the case, and by filling the other end opening side of the case with a filler so as to liquid-tightly close the other end opening.

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