JP2019020175A - Pressure detector - Google Patents

Abstract

To increase the ESD resistance of a pressure sensor while avoiding increase of cost.SOLUTION: A pressure detector 1 includes: a metal housing having a diaphragm 3a, the diaphragm being deformed by pressure from a pressure medium; a sensor element 2 for detecting a pressure by detecting a deformation of the diaphragm 3a; a first lead frame 8 electrically connected to the sensor element 2; a second lead frame 9, which is different from the first lead frame 8; and a connection member 7 for holding the first lead frame 8 and the second lead frame 9. The second lead frame 9 has a discharge terminal 9a exposed from the connection member 7 at a position distant from the metal housing by a predetermined length.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure detection device.

  In order to cope with the environment and improve fuel efficiency of automobiles, the adoption of a hydraulic system that generates hydraulic pressure with an electric motor, a fuel injection system that injects fuel under pressure, and the like is expanding. In these systems, a pressure sensor is provided to detect pressure. In general, a pressure sensor for detecting hydraulic pressure (hereinafter referred to as a pressure sensor) is housed in a metal housing to ensure strength reliability, and is a measurement object such as hydraulic oil or liquid fuel. It is attached by screw tightening to the metal pipe through which the pressure medium flows. The metal pipe is fixed to a structure having a body GND potential, such as an automobile body or an engine. Therefore, the potential of the metal housing of the pressure sensor becomes the body GND potential as in the case of the metal pipe.

  The pressure sensor is provided with a connector terminal for connection to an electronic control unit (ECU: Electronic Control Unit) mounted on the automobile. When the human body touches the connector terminal of the pressure sensor in an environment where measures for preventing electrostatic charge on the human body are not sufficiently taken, such as when manufacturing a pressure sensor, electrostatic discharge (ESD: ElectroStatic Discharge) from the human body to the pressure sensor occurs. Occasionally, a high voltage may be applied to the pressure sensor. A detection element for detecting pressure in the pressure sensor is disposed between the metal casing and an insulating layer. This corresponds to a parasitic capacitance having a relatively large capacitance being electrically connected between the detection element and the metal casing. Therefore, when a high voltage due to ESD is applied to the connector terminal of the pressure sensor when the potential of the metal casing is in the body GND potential as described above, charge flows from the pressure sensor to the parasitic capacitance, and the parasitic capacitance is reduced. Charged. At this time, if a current exceeding the allowable current flows through a processing circuit in the middle, the processing circuit may be destroyed.

  As an ESD countermeasure for solving the above-described problems, techniques described in Patent Documents 1 and 2 are known. Japanese Patent Application Laid-Open No. 2004-228561 extends the terminal connected to the control circuit board, and further forms a protrusion on the terminal, thereby forming a discharge gap between the control circuit board and the body GND body casing. An electronic device is disclosed. Further, in Patent Document 2, the shape of the metal casing on which the circuit board is installed is devised, and a part of the GND terminal is brought close to the protruding portion of the metal casing, thereby discharging between the metal casing and the GND terminal. An in-vehicle electronic device in which a gap is formed is disclosed.

Japanese Patent No. 4577276 Japanese Patent No. 5842898

  In the technologies described in Patent Documents 1 and 2, a discharge gap is formed by devising the terminal structure and the shape of the metal casing, and a high voltage due to ESD is released to the GND potential. Therefore, there is a problem that the number of parts and the number of processing steps increase, resulting in an increase in cost.

  A pressure detection device according to the present invention includes a metal casing having a deformation portion that is deformed by pressure received from a pressure medium, a detection element that detects the pressure by detecting deformation of the deformation portion, and an electrical connection between the detection element and the detection element. A first lead frame connected to the first lead frame, a second lead frame different from the first lead frame, and a structure holding the first lead frame and the second lead frame. The structure is formed with an insertion portion for inserting a connector terminal electrically connected to the detection element via the first lead frame, and the insertion portion includes the first portion. A lead frame and a press terminal for pressing the connector terminal to contact the first lead frame are disposed on the second lead frame. And discharging terminal exposed from the structure at a position apart a predetermined distance from the metal casing is formed.

  According to the present invention, it is possible to improve ESD resistance of a pressure sensor while avoiding an increase in cost.

It is a longitudinal cross-sectional view which shows the structure of the pressure detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows the external appearance of a connection member. It is a figure explaining capacitor formation by parasitic capacitance. It is a figure explaining the difference in the circuit operation | movement at the time of ESD generation | occurrence | production when not applying with this invention. It is a figure which shows the positional relationship of a lead frame and a metal housing | casing. It is a figure which shows the example of a shape of the connection member in the case of comprising a parallel plate capacitor | condenser using an adhesive agent.

  Hereinafter, an embodiment for carrying out the present invention will be described.

  FIG. 1 is a longitudinal sectional view showing a configuration of a pressure detection device 1 according to an embodiment of the present invention. The pressure detection device 1 is used by being mounted on an automobile, and includes a sensor element 2, a pressure port 3, a connector subassembly 5, a base member 6, a connection member 7, a first lead frame 8, and a second lead frame. 9 is provided.

  A rectangular diaphragm 3a that acts as a pressure receiving surface of a pressure medium to be measured is provided on the upper portion of the pressure port 3. The upper surface of the diaphragm 3a, that is, the surface opposite to the pressure receiving surface is a pedestal surface 3b on which the sensor element 2 is placed. The pressure port 3 introduces a pressure medium such as hydraulic oil or liquid fuel to the pressure receiving surface of the diaphragm 3a. Thereby, the diaphragm 3a deform | transforms according to the pressure of a pressure medium, and distortion generate | occur | produces. The sensor element 2 detects, for example, the amount of deformation of the diaphragm 3a, that is, the amount of strain by measuring a change in the resistance value according to the strain of the diaphragm 3a, thereby detecting the pressure of the pressure medium.

  Both the pressure port 3 and the base member 6 are made of metal such as SUS, and are joined to each other by welding or the like. On the base member 6, the connecting member 7 is fixed with an adhesive or the like. Hereinafter, a combination of the pressure port 3 and the base member 6 is referred to as a “metal casing”. There is no problem even if the pressure port 3 and the base member 6 are integrally formed instead of joining the pressure port 3 and the base member 6 to form a metal casing.

  The connector subassembly 5 has a connector terminal 5a. A harness (not shown) is connected to the connector terminal 5a. The pressure detection device 1 is connected to the ECU of the automobile via this harness, and outputs a pressure detection result to the ECU. The connector subassembly 5 is provided with a cover 11 for shielding the sensor element 2 and the like from the outside by integral molding. The cover 11 has a hexagonal shape, for example.

  The connection member 7 is a structure for holding the first lead frame 8 and the second lead frame 9. The connection member 7 is formed with an insertion portion for inserting the connector terminal 5a. In this insertion portion, one end of the first lead frame 8 and one end of the second lead frame 9 are arranged. On the other end side of the first lead frame 8, a bonding portion connected to the sensor element 2 by wire bonding using the wire 10 is provided. For example, aluminum (Al) or gold (Au) is used for the wire 10. By inserting the connector terminal 5a into the insertion portion of the connection member 7, the sensor element 2 is electrically connected to the ECU via the wire 10, the first lead frame 8, the connector terminal 5a, and the harness.

  On the other end side of the second lead frame 9, there is provided a discharge terminal 9a for protecting the sensor element 2 by discharging the high voltage when ESD is applied to the connector terminal 5a. . The discharge terminal 9a is exposed from the connection member 7 at a position spaced apart from the base member 6 constituting the metal casing by a predetermined distance. When the connector terminal 5a is inserted into the insertion portion of the connecting member 7, the connector terminal 5a comes into contact with the second lead frame 9 and is electrically connected to the discharge terminal 9a. When a high voltage due to ESD is applied to the connector terminal 5a in this state, dielectric breakdown occurs between the discharge terminal 9a and the base member 6, and the applied high voltage is discharged from the discharge terminal 9a to the base member 6.

  When assembling the pressure detection device 1, the connection member 7 in which the first lead frame 8 and the second lead frame 9 are assembled is disposed on the base member 6, and the bonding portion between the sensor element 2 and the first lead frame 8 is arranged. Are connected by a wire 10. Thereafter, in order to protect the sensor element 2 from foreign matter or the like, a silicone gel 12 is potted on the surface of the sensor element 2. And the connector subassembly 5 and a metal housing are integrated by joining the cover 11 and the base member 6 with welding etc. in the state in which the connector terminal 5a was inserted in the insertion part of the connection member 7. FIG. Thereby, the pressure detection apparatus 1 is comprised.

  The sensor element 2 is a one-chip pressure detection element in which a strain detection element and a processing circuit are integrally formed on a silicon substrate. Therefore, a circuit board for laying out the processing circuit is not necessary. An output signal generated by the sensor element 2 with respect to the pressure received by the diaphragm 3a is transmitted to the ECU through the wire 10, the first lead frame 8, and the connector terminal 5a through the harness.

  Next, detailed shapes of the connection member 7, the first lead frame 8, and the second lead frame 9 will be described with reference to FIG. FIG. 2 is a view showing the appearance of the connection member 7 in which the first lead frame 8 and the second lead frame 9 are incorporated. In FIG. 2, the left drawing is a projection view of the connecting member 7, and the right drawing is a plan view.

  As shown in FIG. 2, an insertion portion 7 c is formed in the connection member 7. A connector contact portion 8b provided on one end side of the first lead frame 8 and a pressing terminal 9b provided on one end side of the second lead frame 9 are disposed in the insertion portion 7c. A bonding portion 8 a for connecting to the sensor element 2 by wire bonding is provided on the other end side of the first lead frame 8, and the sensor element 2 is connected to the other end side of the second lead frame 9. A discharge terminal 9a is provided for protection from ESD.

  Since the pressing terminal 9b has a spring property, when the connector terminal 5a is inserted into the insertion portion 7c, the pressing terminal 9b is deformed and presses the connector terminal 5a in the direction of the connector contact portion 8b. Thereby, the connector terminal 5a can be reliably brought into contact with the connector contact portion 8b and the pressing terminal 9b, and electrical connection between the connector terminal 5a and the first lead frame 8 and the second lead frame 9 can be ensured.

  The connecting member 7 is provided with an insertion guide 7b for positioning when the connector terminal 5a is inserted into the insertion portion 7c. The position and shape of the insertion guide 7 b are formed so as to correspond to the position and shape of a projection (not shown) provided in the connector subassembly 5. If the insertion guide 7b does not exist, the position and orientation of the connector terminal 5a may be shifted when the connector terminal 5a is inserted into the insertion portion 7c, and the connector terminal 5a may not be accurately in contact with the connector contact portion 8b. Therefore, in the present embodiment, the insertion guide 7b is provided in the connection member 7, so that when the connector subassembly 5 is assembled, the insertion guide 7b is fitted to the protruding portion of the connector subassembly 5 to position the connector terminal 5a. Has been done. By inserting the connector terminal 5a into the insertion portion 7c in such a positioned state, the connector terminal 5a can be brought into precise contact with the connector contact portion 8b.

  Further, the connection member 7 is provided with a mounting portion 7a on which electronic components such as a chip capacitor are mounted. The connector terminal 5a is press-molded into a shape that does not interfere with the electronic component mounted on the mounting portion 7a when inserted into the insertion portion 7c so as not to hinder the mounting of the electronic component on the mounting portion 7a. ing. Thereby, the circuit board can be abolished in the pressure detection device 1. After mounting necessary electronic components, the mounting portion 7a is potted with the silicone gel 12 in the same manner as the sensor element 2 to protect the surface (see FIG. 1).

  As described above, the pressing terminal 9b forms a spring for bringing the connector terminal 5a into contact with the connector contact portion 8b in the insertion portion 7c. When the connecting member 7 is molded, a plurality of second lead frames 9 are integrated by a carrier, and after the completion of molding, the second lead frames 9 are separated through a cutting process. The cut portion of each second lead frame 9 at this time is exposed from the connection member 7 at a position spaced apart from the contact surface of the connection member 7 with the base member 6 and is used as the discharge terminal 9a. That is, in the second lead frame 9 incorporated in the connection member 7, the discharge terminal 9a is automatically formed through a cutting process.

  Next, the discharge terminal 9a, which is a feature of this embodiment, will be described below with reference to FIGS.

  FIG. 3 is a partially enlarged view of the pressure port 3 on which the sensor element 2 is placed. As shown in FIG. 3, the sensor element 2 is bonded onto the pressure port 3 via a bonding agent 4. As described above, the sensor element 2 has a one-chip configuration in which the strain detection element and the processing circuit are integrally formed. The bonding agent 4 is an insulator such as an inorganic adhesive, for example, and is applied with a very thin thickness compared to the area of the sensor element 2. For this reason, on the circuit including the sensor element 2, the joint portion between the sensor element 2 and the pressure port 3 with the bonding agent 4 interposed therebetween acts as a parasitic capacitance Cic having a relatively large capacity.

  FIG. 4 is a diagram for explaining the operation of the discharge terminal 9a on the circuit having the parasitic capacitance Cic. FIG. 4A shows a circuit schematic diagram when the discharge terminal 9a is not provided, and FIG. 4B shows a circuit schematic diagram when the discharge terminal 9a is provided. The IC and the protection circuit shown in these circuit schematic diagrams indicate circuits constituted by electronic components mounted on the mounting portion 7a of the sensor element 2 and the connection member 7.

  When the human body touches the connector terminal 5a in a state where the connector terminal 5a is inserted into the insertion portion 7c of the connection member 7 at the time of manufacturing the pressure detecting device 1, the electric charge accumulated in the human body is discharged by ESD, and the connector terminal A high voltage may be applied to 5a. At this time, in the case of FIG. 4A in which the discharge terminal 9a is not provided, charging from the human body via the connector terminal 5a, the protection circuit, the IC, and the parasitic capacitance CiC to the metal casing of the body GND potential. A path is formed. Therefore, most of the electric charge released from the human body toward the connector terminal 5a flows into the parasitic capacitance CiC having a relatively large capacitance. At that time, when a high-voltage current flows through the IC, that is, the processing circuit of the sensor element 2, the resistance element or the like in the processing circuit may be burned by Joule heat, and the sensor element 2 may be destroyed. In order to avoid malfunction of the processing circuit due to noise, a capacitor that acts as a noise path may be provided between the wiring from the connector terminal 5a to the protection circuit and the metal housing. Since at least a part of the electric charge flows into the parasitic capacitance CiC, the sensor element 2 may similarly be destroyed. However, when the high voltage applied to the connector terminal 5a is a negative voltage, the flow of charges is reversed from that in FIG.

  On the other hand, in the case of FIG. 4B in which the discharge terminal 9a is provided, a discharge gap is formed between the discharge terminal 9a and the metal casing. When the charge due to ESD flows from the connector terminal 5a, the potential of the protection circuit and the IC rises with respect to the GND potential of the metal casing. When the potential gradient of the discharge gap reaches the breakdown level of air, the discharge gap is broken down, and discharge is generated from the discharge terminal 9a toward the metal casing. As a result, the electric charge released from the human body toward the connector terminal 5a flows from the discharge terminal 9a into the metal casing without passing through the IC. Thereby, it is possible to prevent a high-voltage current from flowing through the IC and to prevent the sensor element 2 from being destroyed. In addition, as shown in FIG.4 (b), it is preferable to provide the discharge gap by the discharge terminal 9a in the connector terminal 5a side rather than the protection circuit comprised by the electronic component mounted in the mounting part 7a.

  In the case of FIG. 4B, the dielectric breakdown level in the discharge gap can be adjusted by adjusting the distance between the discharge terminal 9a and the metal casing. In order to prevent destruction of the sensor element 2 due to ESD, it is necessary to cause dielectric breakdown of the discharge gap at a voltage level lower than the withstand voltage of the sensor element 2. Here, it is known that the dielectric breakdown of air generally occurs when the electric potential gradient E [V / m] is 3 [MV / m] or more.

  Further, the shape of the tip of the discharge terminal 9a is greatly involved in the voltage level at which the dielectric breakdown of the discharge gap occurs. Specifically, the sharper the tip of the discharge terminal 9a, the higher the potential gradient of the discharge gap, and the easier it is to discharge due to dielectric breakdown. Here, the discharge terminal 9a is formed on the second lead frame 9 by the cutting process after the molding of the connection member 7 as described above. Therefore, the tip shape of the discharge terminal 9a is generally sharply sharpened by cutting. Therefore, even at a relatively low voltage level, dielectric breakdown can occur in the discharge gap between the discharge terminal 9a and the metal housing, and the sensor element 2 can be more reliably prevented from being broken.

  FIG. 5 is a diagram showing the positional relationship between the first lead frame 8 and the second lead frame 9 and the metal housing. In FIG. 5, in order to facilitate understanding of the positional relationship between the first lead frame 8 and the second lead frame 9 and the metal housing, a portion of the connector subassembly 5 excluding the tip of the connector terminal 5 a and the connection member 7. And the external appearance of the pressure detection device 1 is shown by a front view.

  In the pressure detection apparatus 1 of the present embodiment, the lower surface of the first lead frame 8, that is, the surface on the base member 6 side, and the upper surface of the base member 6 in the metal housing are connecting members that are insulators. 7 are arranged opposite to each other at a predetermined interval with a resin or adhesive 7 interposed therebetween. Accordingly, a parallel plate capacitor having a parasitic capacitance Ct is formed between the first lead frame 8 and the metal casing in a section indicated by a broken line in FIG. As shown in FIG. 5, the parallel plate capacitor region is in contact with the connector terminal 5a on the electrical path rather than the mounting portion 7a on which the electronic component is mounted in the bonding portion 8a connected to the sensor element 2 and the connection member 7. It is preferable to form at a position close to the connector contact portion 8b. By providing Ct in parallel with the parasitic capacitance Cic, the ESD charge can be shunted, and an effect of reducing the influence of Cic is expected.

  Further, the second lead frame 9 is formed with a discharge terminal 9a and a pressing terminal 9b. As shown in FIG. 5, the discharge terminal 9 a is disposed at a predetermined distance from the metal housing at a position different from the parallel plate capacitor region formed by the first lead frame 8. In order to facilitate discharge, the tip shape of the discharge terminal 9a is sharply pointed as described above. By doing so, unnecessary discharge from other than the discharge terminal 9a is eliminated, and the sensor element 2 can be more reliably protected from ESD high voltage. Unlike the parallel plate capacitor region of the first lead frame 8, in order to avoid carbonization due to discharge, the resin or adhesive of the connecting member 7 is disposed between the tip of the discharge terminal 9a and the metal housing. Preferably not.

  The distance between the discharge terminal 9a and the metal housing is preferably set in the range of 0.1 [mm] to 0.6 [mm]. The reason for this will be described below.

  In the case of an automotive part such as the pressure detection device 1, high voltage noise (surge) that is generated from another automotive part having a large inductance may be input. Even when a surge voltage of about several hundreds [V] is input, it is necessary to maintain a certain distance so as to ensure insulation between the discharge terminal 9a and the metal casing and not to be in a conductive state. .

  As described above, it is known that the breakdown of air generally occurs when the potential gradient E [V / m] is 3 [MV / m] or more. Here, the value of the surge voltage generally assumed in the surge test is about 300 [V]. When these values are applied to the equation of potential gradient E [V / m], that is, E = V / d (where V: voltage [V], d: distance between electrode plates [m]), The minimum distance between the metal housings is calculated as 0.1 [mm].

  On the other hand, in order to prevent the destruction of the sensor element 2 due to ESD, as described above, the dielectric breakdown of the discharge gap needs to occur at a voltage level lower than the withstand voltage of the sensor element 2. Here, the withstand voltage required for the sensor element 2 is, for example, 2 [kV] which is one of the standard values of the ESD withstand voltage test in the human body model. Therefore, the distance between the discharge terminal 9a and the metal casing must be set so that the breakdown of the discharge gap is surely generated at a voltage less than the standard value and the discharge is performed from the discharge terminal 9a.

  As a value allowing for a margin with respect to the standard value 2 [kV], for example, when the voltage level is 1.8 [kV] or higher, dielectric breakdown occurs between the discharge terminal 9a and the metal casing. In this case, when d = 0.6 [mm] in the above-described equation of the potential gradient E [V / m], the potential gradient E [V / m] is 3 [MV] when V = 1.8 [kV]. / M]. Therefore, the maximum distance between the discharge terminal 9a and the metal housing is calculated as 0.6 [mm].

  As described above, it is desirable to set the distance between the discharge terminal 9a and the metal casing in a range of a lower limit value of 0.1 [mm] or more and an upper limit value of 0.6 [mm] or less. However, it is also possible to employ only one of these lower limit value and upper limit value. That is, when it is not necessary to consider the surge voltage, the distance between the discharge terminal 9a and the metal housing may be less than 0.1 [mm]. When the withstand voltage of the sensor element 2 is high, the distance between the discharge terminal 9a and the metal housing may be larger than 0.6 [mm].

  When the connecting member 7 is made of a mold resin, there is a minimum thickness that can be disposed between the first lead frame 8 or the second lead frame 9 and the metal housing due to restrictions during molding. Therefore, by using a connection member having a shape different from that of the connection member 7, the resin of the connection member is not disposed between the first lead frame 8 and the second lead frame 9 and the metal housing (base member 6). An adhesive that joins the connecting member and the base member 6 may be used as a dielectric of the parallel plate capacitor.

  FIG. 6 is a diagram showing an example of the shape of a connection member when a parallel plate capacitor is configured using an adhesive. In the connection member 13 shown in FIG. 6A, the first lead frame 8 with the lower surface in the parallel plate region of the first lead frame 8, that is, the surface on the base member 6 side exposed from the connection member 13. Is attached to the connecting member 13. When the connection member 13 to which the first lead frame 8 is attached is placed on the base member 6, the first lead is formed from the bottom surface of the connection member 13, that is, the surface of the connection member 13 facing the metal housing (base member 6). A part of the frame 8, that is, a surface facing the base member 6 of the first lead frame 8 is exposed. In this state, the connection member 13 is attached to the base member 6 with an insulating adhesive. However, as described above, in order to avoid carbonization of the adhesive due to discharge, the adhesive is not disposed between the discharge terminal 9a and the metal casing (base member 6). Then, the adhesive acts as a dielectric of the parallel plate capacitor, and a parasitic capacitance Ct is formed between the first lead frame 8 and the metal housing. At this time, a desired capacitance value can be obtained in the parasitic capacitance Ct by controlling the amount of the adhesive and adjusting the thickness of the adhesive layer.

  Moreover, you may use the connection member 14 shown in FIG.6 (b). On the bottom surface of the connecting member 14, a wall portion 14a formed along the outer edge and a filling portion 14b surrounded by the wall portion 14a are provided. The filling part 14b is recessed rather than the wall part 14a with respect to the bottom face. Similarly to the connection member 13 in FIG. 6A, this connection member 14 is also in a state where the lower surface in the parallel plate region of the first lead frame 8, that is, the surface on the base member 6 side is exposed from the connection member 14. The first lead frame 8 is attached to the connection member 14. When the connection member 14 to which the first lead frame 8 is attached is placed on the base member 6, the bottom surface of the wall portion 14a comes into contact with the metal casing (base member 6). At this time, you may make it perform positioning at the time of attaching the connection member 14 to a metal housing | casing by the wall part 14a. Further, a groove or step corresponding to the protruding shape of the wall 14a is formed on the metal casing side, and the wall 14a is aligned with the groove or step so that the connecting member 14 is positioned. Also good. Further, a state in which a part of the first lead frame 8, that is, a surface facing the base member 6 of the first lead frame 8 is exposed from the surface of the filling portion 14b facing the metal casing (base member 6). Become. In this state, the filling portion 14 b is filled with an insulating adhesive, and the connection member 14 is attached to the base member 6. However, in this case as well, as described above, in order to avoid carbonization of the adhesive due to electric discharge, the adhesive is not arranged between the discharge terminal 9a and the metal casing (base member 6). Then, as in the case of the connection member 13, the adhesive acts as a dielectric for the parallel plate capacitor, and a parasitic capacitance Ct is formed between the first lead frame 8 and the metal housing. Since the thickness of the adhesive layer at this time becomes the height of the wall portion 14a, variations in the distance between the first lead frame 8 and the discharge terminal 9a and the metal housing can be suppressed. Therefore, by adjusting the height of the wall portion 14a, a desired capacitance value can be accurately obtained in the parasitic capacitance Ct, and variations in the discharge voltage can be suppressed. Note that a part of the first lead frame 8 may not be exposed in the filling portion 14b.

  Further, when the connection member 14 is attached to the metal casing, the metal casing may protrude toward the first lead frame 8 in the filling portion 14b with respect to the bottom surface of the wall portion 14a. For example, a table-like convex part with a flat top is formed on a metal casing, and when attaching the connecting member 14, the convex part is inserted into the concave part of the filling part 14b as described above. Can be realized. Alternatively, as described above, the above-described arrangement can also be realized by providing a groove corresponding to the protruding shape of the wall portion 14a in the metal housing and fitting the wall portion 14a into the groove. As a result, since the metal casing and the first lead frame 8 can be arranged at a distance smaller than the minimum resin thickness due to the restrictions at the time of molding as described above, the parasitic capacitance Ct can be increased.

  Similarly, when the connection member 14 is attached to the metal casing, the metal casing may protrude toward the discharge terminal 9a with respect to the bottom surface of the wall portion 14a. As a result, the metal casing and the discharge terminal 9a can be arranged at a distance smaller than the minimum resin thickness due to the restrictions at the time of molding as described above, so that the discharge voltage can be reduced.

In order to improve the ESD tolerance of the pressure detection device 1, it is also effective to reduce the capacitance value of the parasitic capacitance Cic. Specifically, for example, by increasing the thickness of the bonding agent 4 that bonds the sensor element 2 to the pressure port 3, the capacitance value of the parasitic capacitance Cic can be reduced. Here, the parallel plate capacitor capacitance C [F] is defined as C = ε ·, where S [m ² ] is the area of the plates, d [m] is the distance between the plates, and ε [F / m] is the dielectric constant. It is represented by the formula of S / d. From this equation, it can be seen that the parallel plate capacitor capacitance C decreases as the electrode distance d increases. Therefore, by increasing the thickness of the bonding agent 4 within a range that does not affect the strain detection performance of the sensor element 2 and increasing the distance between the sensor element 2 and the pressure port 3, the capacitance value of the parasitic capacitance CiC is reduced. It is possible to improve the ESD tolerance of the pressure detection device 1.

  According to one embodiment of the present invention described above, the following operational effects are obtained.

(1) A pressure detecting device 1 includes a deforming portion that is deformed by pressure received from a pressure medium, that is, a metal housing having a diaphragm 3a, a sensor element 2 that detects pressure by detecting deformation of the deforming portion, and a sensor element. 2, a first lead frame 8 electrically connected to the second lead frame 9, a second lead frame 9 different from the first lead frame 8, and a structure that holds the first lead frame 8 and the second lead frame 9, that is, a connection Member 7. The connecting member 7 is formed with an insertion portion 7 c for inserting a connector terminal 5 a electrically connected to the sensor element 2 via the first lead frame 8. A first lead frame 8 and a pressing terminal 9b for pressing the connector terminal 5a to contact the first lead frame 8 are arranged in the insertion portion 7c. The second lead frame 9 is formed with a press terminal 9b and a discharge terminal 9a exposed from the connection member 7 at a position spaced apart from the metal housing by a predetermined distance. Since it did in this way, ESD tolerance of the pressure detection apparatus 1 which is a pressure sensor can be improved, avoiding a cost increase.

(2) The first lead frame 8 has a connection portion connected to the sensor element 2 by wire bonding, that is, a bonding portion 8a, and a connector contact portion 8b to which the connector terminal 5a pressed by the pressing terminal 9b contacts. The electronic component is connected on the electrical path between the bonding portion 8a and the connector contact portion 8b. Since it did in this way, the noise tolerance of the pressure detection apparatus 1 can be improved.

(3) The connection member 7, 13 or 14 is joined to the metal casing by an adhesive. This adhesive is not disposed between the discharge terminal 9a and the metal casing. Since it did in this way, carbonization of the adhesive agent by discharge can be avoided and it can prevent that the discharge terminal 9a and a metal housing | casing conduct | electrically_connect.

(4) The adhesive is an insulator, and the first surface of the first lead frame 8, that is, the surface on the metal housing side in the parallel plate region, and the second surface of the metal housing, that is, the base member 6. The upper surface is disposed opposite to the adhesive with the adhesive interposed therebetween. Since it did in this way, a parasitic capacitance can be produced between the 1st lead frame 8 and a metal housing | casing, and the noise resistance of the pressure detection apparatus 1 which is a pressure sensor can be improved.

(5) The connection member 14 has a contact surface in contact with the metal casing, that is, the bottom surface of the wall portion 14a, and a filling portion 14b that is recessed with respect to the contact surface and is filled with an adhesive. If such a connection member 14 is used, the discharge voltage at which discharge from the discharge terminal 9a is performed can be set to a desired voltage value by adjusting the height of the wall portion 14a.

(6) The predetermined distance between the discharge terminal 9a and the metal housing is preferably 0.1 mm or more. In this way, conduction between the discharge terminal 9a and the metal casing due to the input of the surge voltage can be avoided.

(7) Moreover, it is preferable that the predetermined space | interval between the discharge terminal 9a and a metal housing | casing is 0.6 mm or less. If it does in this way, dielectric breakdown will be produced between the discharge terminal 9a and a metal housing | casing below withstand voltage of the sensor element 2, and damage to the sensor element 2 can be avoided.

(8) The metal housing includes the pressure port 3 for introducing the pressure medium into the deforming portion, and the base member 6 joined to the connection member 7. Since it did in this way, the pressure detection apparatus 1 with high noise resistance can be comprised.

  In the above-described embodiment, the description has been given by taking the one-chip type sensor element 2 in which the strain detection element and the processing circuit are integrated as an example. However, a sensor element other than the one-chip type, that is, the strain gauge and the processing circuit, The present invention can be similarly applied to sensor elements formed on different substrates. In this case, since the strain gauge is generally arranged in a state of being insulated at a location closest to the metal casing, a parasitic capacitance having a large capacitance value is formed between the strain gauge and the metal casing. Therefore, the sensor element may be destroyed by passing through the processing circuit when the charge due to ESD flows into the parasitic capacitance. Therefore, even in this case, the same measures as in the embodiment are effective.

  Moreover, although the pressure detection apparatus 1 demonstrated in embodiment was mounted in the motor vehicle and demonstrated as what detects the pressure of pressure media, such as hydraulic oil and liquid fuel, also about the pressure detection apparatus used for another use, Similarly, the present invention can be applied. As long as the sensor element is arranged close to the metal casing in an insulated state and the metal casing is at a GND potential, the ESD resistance improvement according to the present invention can be effectively achieved for various pressure detection devices. Can act. For example, in a sensor that detects a load as strain, a large force is applied to the sensor, and therefore resin or the like cannot be used for the pressure receiving portion. In addition, it is necessary to firmly configure the pedestal of the sensor element. Accordingly, the casing of such a sensor is necessarily made of metal, and has a configuration similar to that of the pressure detection device 1 described in the embodiment. Therefore, the ESD resistance can be improved by applying the present invention in the same manner. Can be planned.

  As described above, the sensor element used in the sensor may be a one-chip type sensor element in which the strain detection element and the processing circuit are integrated, or may be formed on separate substrates. It may be. In either case, the same effects as described in the embodiment can be obtained.

  The pressure detection device to which the present invention is applied is not limited to the donut shape as described in the embodiment, and may have other shapes. As long as the technical elements as described above are incorporated, there is no problem in any shape.

  As described above, by applying the present invention to the pressure detection device, it is possible to improve the ESD resistance without generating a dissimilar metal bond and without performing special processing. Further, since this is a configuration that does not use a chip capacitor, it can be expected to improve connection reliability, reduce costs, and save space.

  The embodiment and various modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. Moreover, although various embodiment and the modification were demonstrated above, this invention is not limited to these content. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Pressure detection apparatus 2 Sensor element 3 Pressure port 3a Diaphragm 3b Base surface 4 Bonding agent 5 Connector subassembly 5a Connector terminal 6 Base member 7 Connection member 7a Mounting part 7b Insertion guide 7c Insertion part 8 1st lead frame 8a Bonding part 8b Connector contact portion 9 Second lead frame 9a Discharge terminal 9b Press terminal 10 Wire 11 Cover 12 Silicone gel

Claims (8)

A metal housing having a deforming portion that is deformed by pressure received from the pressure medium;
A detection element that detects the pressure by detecting the deformation of the deformation portion;
A first lead frame electrically connected to the detection element;
A second lead frame different from the first lead frame;
A structure for holding the first lead frame and the second lead frame,
The structure is formed with an insertion portion for inserting a connector terminal electrically connected to the detection element via the first lead frame,
In the insertion portion, the first lead frame and a pressing terminal for pressing the connector terminal to contact the first lead frame are arranged,
The pressure detection device, wherein the second lead frame is formed with the pressing terminal and a discharge terminal exposed from the structure at a position spaced apart from the metal housing by a predetermined distance. The pressure detection device according to claim 1,
The first lead frame has a connection portion connected to the detection element by wire bonding, and a contact portion to which the connector terminal pressed by the pressing terminal comes into contact,
A pressure detection device in which an electronic component is connected on an electrical path between the connection portion and the contact portion. The pressure detection device according to claim 1 or 2,
The structure is bonded to the metal casing by an adhesive,
The pressure detection device in which the adhesive is not disposed between the discharge terminal and the metal casing. The pressure detection device according to claim 3,
The adhesive is an insulator;
A pressure detection device in which a first surface of the first lead frame and a second surface of the metal housing are arranged to face each other with the adhesive interposed therebetween. The pressure detection device according to claim 4,
The said structure is a pressure detection apparatus which has the contact surface which contact | connects the said metal housing | casing, and the filling part which is depressed with respect to the said contact surface and is filled with the said adhesive agent. In the pressure detection device according to any one of claims 1 to 5,
The pressure detecting device, wherein the predetermined interval is 0.1 mm or more. In the pressure detection device according to any one of claims 1 to 6,
The pressure detecting device, wherein the predetermined interval is 0.6 mm or less. In the pressure detection device according to any one of claims 1 to 7,
The metal casing includes a pressure port for introducing the pressure medium into the deforming portion, and a base member joined to the structure.

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