JP2016031301A - Sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress variations of characteristics of a sensor device.SOLUTION: A sensor device according to the present invention comprises: a circuit board on which a flow rate detection unit and electronic components configuring a control circuit for controlling the flow rate detection unit are mounted; a resin housing covering the circuit board; a soft layer covering at least the top face of the electronic components mounted on the circuit board; and a hard layer interposed between the soft layer and the resin housing. The plastic housing is integrated with the hard layer in at least a portion of the hard layer, and the flow rate detection unit is exposed from the housing.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a sensor device.

  For example, an internal combustion engine such as an automobile is provided with an electronically controlled fuel injection device. The electronically controlled fuel injection device has a role of efficiently operating the internal combustion engine by appropriately adjusting the amount of gas and fuel flowing into the internal combustion engine. For this reason, in the electronically controlled fuel injection device, it is necessary to accurately grasp the gas flowing into the internal combustion engine. For this reason, the electronically controlled fuel injection device is provided with a flow rate sensor (also referred to as an air flow sensor or the like) that measures the flow rate of gas.

  The flow sensor module is formed by joining a substrate mounted with a sensor such as a pressure sensor and a humidity sensor to a housing (housing) in addition to electronic components such as a flow detection unit, a control circuit unit, and a microcomputer. The Conventionally, the substrate on which the electronic component is mounted and the housing formed by the resin mold are bonded with an adhesive. However, in order to reduce costs, the periphery of the substrate on which the electronic component is mounted is molded with the housing resin. Therefore, it is known that the substrate and the housing are directly joined without using an adhesive (see Patent Document 1).

JP 2008-1111859 A

  However, when the periphery of the board on which electronic components are mounted is molded with housing resin, the molding shrinkage force of the housing resin is loaded on the electronic components that control the sensor, and there is a risk that the characteristics of the sensor may fluctuate before and after molding. is there.

  A sensor device according to the present invention includes a flow rate detection unit, a substrate on which electronic components constituting a control circuit that controls the flow rate detection unit are mounted, a resin housing that covers the substrate, and an electronic component mounted on the substrate. A soft layer covering the upper surface, and a hard layer interposed between the soft layer and the resin housing. The resin housing is integrated with the hard layer at least at a part of the hard layer, and the flow rate detection unit is provided. Exposed.

  According to the present invention, fluctuations in characteristics as a sensor can be suppressed.

It is a system block diagram which shows one Embodiment at the time of using the flow sensor of this invention for an internal combustion engine control system. It is a perspective view which shows the external appearance of a flow sensor. It is the typical figure which looked at the housing before mounting | wearing with a front cover from the front side. It is the typical figure which looked at the housing before mounting | wearing with a back cover from the back side. It is a figure which shows the mounting structure of the front surface of a board | substrate. It is a figure which shows the mounting structure of the back surface of a board | substrate. It is the figure which showed typically the AA arrow cross section of FIG. It is the figure which looked at the front surface of the board | substrate after installing a soft layer. It is the figure which looked at the front surface of the board | substrate after installing a hard layer. FIG. 9 is a diagram corresponding to FIG. 7 of the first embodiment in the second embodiment. FIG. 9 is a diagram corresponding to FIG. 7 of the first embodiment in the second embodiment. FIG. 10 is a diagram corresponding to FIG. 7 of the first embodiment in the third embodiment. FIG. 10 is a diagram corresponding to FIG. 7 of the first embodiment in the third embodiment. FIG. 10 is a diagram corresponding to FIG. 7 of the first embodiment in the fourth embodiment. FIG. 10 is a diagram corresponding to FIG. 7 of the first embodiment in the fifth embodiment. FIG. 10 is a diagram corresponding to FIG. 7 of the first embodiment in the fifth embodiment. It is a figure which shows the analysis model in the example of a prior art structure. It is a figure which shows the structure of the analysis model in 2nd Embodiment shown in FIG. It is a figure which shows the structure of the analysis model in 3rd Embodiment shown in FIG. It is a graph which shows the analysis result regarding the transmission inhibitory effect of the shrinkage distortion of housing resin. It is a graph which shows the analysis result of the temperature of the electronic component interface regarding the heat transfer suppression effect at the time of injection molding. It is a figure which shows a modification.

--- First embodiment ---
A first embodiment of a sensor device according to the present invention will be described with reference to FIGS. FIG. 1 is a system diagram showing an embodiment in which a flow rate sensor, which is a sensor device according to the present invention, is used in an electronic fuel injection internal combustion engine control system. Based on the operation of the internal combustion engine 110 including the engine cylinder 112 and the engine piston 114, the intake air is sucked from the air cleaner 122 as the gas to be measured 30 and passes through the main passage 124 such as the intake body, the throttle body 126, and the intake manifold 128. To the combustion chamber of the engine cylinder 112. The flow rate of the gas 30 to be measured, which is the intake air introduced to the combustion chamber, is measured by the flow sensor 300 according to the present invention, and fuel is supplied from the fuel injection valve 152 based on the measured flow rate, and the air to be measured is the intake air. The gas 30 is introduced into the combustion chamber in the state of an air-fuel mixture. The flow sensor 300 is typically a thermal flow sensor that measures the state of the gas to be measured flowing through the auxiliary passage by performing heat transfer with the gas to be measured.

  In the present embodiment, the fuel injection valve 152 is provided in the intake port of the internal combustion engine, and the fuel injected into the intake port forms an air-fuel mixture with the measured gas 30 that is intake air, and passes through the intake valve 116. It is guided to the combustion chamber and burns to generate mechanical energy.

  In recent years, as a method excellent in exhaust gas purification and fuel consumption improvement in many vehicles, a method in which a fuel injection valve 152 is attached to a cylinder head of an internal combustion engine and fuel is directly injected into each combustion chamber from the fuel injection valve 152 has been adopted. . The flow sensor 300 of the present invention can be used not only for the method of injecting fuel into the intake port of the internal combustion engine shown in FIG. 1 but also for the method of directly injecting fuel into each combustion chamber. The basic concept of the control parameter measurement method including the usage method of the flow rate sensor 300 and the control method of the internal combustion engine including the fuel supply amount and the ignition timing is substantially the same for both types. A method of injecting fuel is shown in FIG.

  The fuel and air guided to the combustion chamber are in a mixed state of fuel and air, and are burned explosively by the spark ignition of the spark plug 154 to generate mechanical energy. The combusted gas is guided from the exhaust valve 118 to the exhaust pipe, and exhausted as exhaust 24 from the exhaust pipe to the outside of the vehicle. The flow rate of the gas 30 to be measured, which is the intake air led to the combustion chamber, is controlled by a throttle valve 132 whose opening degree changes based on the operation of the accelerator pedal. The fuel supply amount is controlled based on the flow rate of the intake air guided to the combustion chamber. The driver can control the mechanical energy generated by the internal combustion engine by controlling the opening of the throttle valve 132 and controlling the flow rate of the intake air introduced into the combustion chamber.

  The flow rate and temperature of the gas 30 to be measured, which is intake air that is taken in from the air cleaner 122 and flows through the main passage 124, are measured by the flow sensor 300, and an electrical signal that represents the flow rate and temperature of the intake air is sent from the flow sensor 300 to the control device 200. Entered. Further, the output of the throttle angle sensor 144 that measures the opening degree of the throttle valve 132 is input to the control device 200, and the positions and states of the engine piston 114, the intake valve 116, and the exhaust valve 118 of the internal combustion engine, and the rotation of the internal combustion engine. In order to measure the speed, the output of the rotation angle sensor 146 is input to the control device 200. The output of the oxygen sensor 148 is input to the control device 200 in order to measure the state of the mixture ratio between the fuel amount and the air amount from the state of the exhaust 24.

  The control device 200 calculates the fuel injection amount and the ignition timing based on the flow rate of the intake air that is the output of the flow rate sensor 300 and the rotational speed of the internal combustion engine that is measured based on the output of the rotation angle sensor 146. Based on these calculation results, the amount of fuel supplied from the fuel injection valve 152 and the ignition timing ignited by the spark plug 154 are controlled. The fuel supply amount and ignition timing are actually based on the intake air temperature and throttle angle change state measured by the flow sensor 300, the engine speed change state, and the air-fuel ratio state measured by the oxygen sensor 148. It is finely controlled. The control device 200 further controls the amount of air that bypasses the throttle valve 132 by the idle air control valve 156 in the idle operation state of the internal combustion engine, thereby controlling the rotational speed of the internal combustion engine in the idle operation state.

<About the flow sensor 300>
FIG. 2 is a perspective view showing the appearance of the flow sensor 300 as viewed from the upstream side of the main passage 124. The flow sensor 300 includes a housing 301 including a housing 302, a front cover 303, and a back cover 304. The housing 302 and the front cover 303 and the housing 302 and the back cover 304 are welded, for example, by laser irradiation. FIG. 3 is a schematic view of the housing 302 before mounting the front cover 303 as viewed from the front side, and FIG. 4 is a schematic view of the housing 302 before mounting the back cover 304 as viewed from the back side. is there. For convenience of explanation, the front and back of the housing 302 are determined as described above. The flow sensor 300 is parallel to the surface of the substrate 1 to be described later, the flow direction of the gas 30 to be measured in the main passage 124 is the X direction, the direction parallel to the surface of the substrate 1 and perpendicular to the X direction is the Y direction. The direction perpendicular to the surface of the substrate 1 is taken as the Z direction.

  The housing 302 measures a flow rate and the like, a flange 312 for fixing the flow sensor 300 to the intake body as the main passage 124, an external connection unit 305 having an external terminal for electrical connection with an external device, and the like. A measuring unit 310 is provided. A sub-passage groove for creating a sub-passage is provided inside the measurement unit 310, and further, the flow rate detection unit 3, the pressure sensor 5, the humidity sensor 6, electronic components, and the like are mounted inside the measurement unit 310. A substrate 1 is provided. As shown in FIG. 3, the measurement unit 310 is provided with a connector-side connection unit 11 that is electrically connected to an external terminal (not shown) of the external connection unit 305. The connector side connecting portion 11 and a board side connecting portion 12 (to be described later) of the substrate 1 are electrically connected by a wire 13.

  The peripheral portions of the flow rate detection unit 3 and the flow rate detection unit 3 of the substrate 1 are exposed from a flow rate detection opening 306 a provided in the surface portion 306 of the housing 302. The connector-side connecting portion 11, the board-side connecting portion 12, and the peripheral portion of the board-side connecting portion 12 of the substrate 1 are exposed from a connecting-portion opening 306 b provided in the surface portion 306 of the housing 302. The back surface side of the peripheral portion of the flow rate detection unit 3 of the substrate 1 is exposed from a flow rate detection opening 307 a provided on the back surface portion 307 of the housing 302. The area of the pressure sensor 5 and the humidity sensor 6 and the peripheral edge of the substrate 1 is exposed from a sensor outlet opening 307 b provided on the back surface 307 of the housing 302.

  The flow rate detection unit 3 is a sensor for measuring the flow rate of the measurement target gas 30 flowing through the main passage 124, and is mounted on the lower surface of the front surface 1 a of the substrate 1. The pressure sensor 5 is a sensor for measuring the pressure of the measurement target gas 30 flowing through the main passage 124, and is mounted on the back surface 1 b of the substrate 1. The humidity sensor 6 is a sensor for measuring the humidity of the measurement target gas 30 flowing through the main passage 124, and is mounted on the back surface 1 b of the substrate 1.

  The measuring unit 310 of the flow sensor 300 has a shape that extends long from the flange 312 toward the center of the main passage 124, and a tip part of the measuring unit 310 takes in a part of the measurement target gas 30 such as intake air into the sub passage. Outlets 352a and 352b for returning the measured gas 30 from the inlets 350a and 350b and the auxiliary passage to the main passage 124 are provided. The measuring unit 310 has a shape that extends long along the axis from the outer wall of the main passage 124 toward the center, but the width has a narrow shape as shown in FIG. That is, the measurement unit 310 of the flow sensor 300 has a side surface that is thin and has a substantially rectangular front surface. Thereby, the flow sensor 300 can be provided with a sufficiently long sub-passage, and the fluid resistance of the gas to be measured 30 can be suppressed to a small value.

  The gas 30 to be measured that has flowed into the sub-passage from the inlet 350a passes through the flow rate detector 3 as shown by the arrow 30a in FIG. . Although not shown, the housing 302 has a guide groove that guides the gas 30 to be measured from the inlet 350a to the flow rate detector 3 and a guide groove that guides the gas 30 to be measured from the flow rate detector 3 to the outlet 352a in a spiral shape. Is formed.

  The measured gas 30 flowing into the auxiliary passage from the inlet 350b passes through the pressure sensor 5 and the humidity sensor 6 as shown by an arrow 30c in FIG. 4, flows in the auxiliary passage as shown by an arrow 30d, and exits 352b. Spill from.

  In the present embodiment, in flow sensor 300, substrate 1 on which each sensor and electronic component are mounted and housing 302 are integrated by resin molding such as injection molding as will be described later. The surface on which the flow rate detection unit 3 and the microcomputer 4 of the substrate 1 are mounted is the front surface 1a as described above, and the opposite surface is the back surface 1b.

  FIG. 5 is a view showing a mounting structure of the front surface 1 a of the substrate 1. On the front surface 1a of the substrate 1, a plurality of electronic components including a flow rate detection unit 3, a control circuit 7 for processing the signal, a microcomputer 4 for processing information such as flow rate, pressure and humidity, and other chip resistors 8 is implemented. On the front surface 1 a of the substrate 1, a substrate side connection portion 12 for connecting to the connector side connection portion 11 is provided.

  FIG. 6 is a diagram illustrating a mounting structure of the back surface 1 b of the substrate 1. For example, a pressure sensor 5 and a humidity sensor 6 are mounted on the back surface 1 b of the substrate 1. Signals output from the pressure sensor 5 and the humidity sensor 6 are processed by the microcomputer 4 mounted on the front surface 1 a of the substrate 1.

  The housing 302 is integrally molded on the outside of the substrate 1 on which electronic components and the like are mounted by resin molding. Mounted products other than the flow rate detection unit 3, the pressure sensor 5, and the humidity sensor 6 that must be exposed for measurement are covered with a housing 302 for protection. In the following description, the resin constituting the housing 302 is referred to as housing resin.

  For example, when an electronic component such as the microcomputer 4 is covered in a state of being in direct contact with the housing resin, a force due to contraction of the housing resin having a volume much larger than that of the substrate 1 directly acts on the electronic component, and before and after molding the housing 302 There is a risk that the characteristics of the sensor are likely to fluctuate. The electronic component is mounted on the substrate 1 by soldering. The melting temperature of the solder is 220 to 260 ° C., whereas the resin temperature when the housing 302 is molded from a thermoplastic resin is 200 to 300 ° C. It is equivalent to the melting temperature of Therefore, for example, when the housing 302 is molded by injection molding in which a resin flows at a high pressure, there is a possibility that the solder connection portion may come off. Even if the solder connection portion does not come off, the molding shrinkage force of the housing resin acts not only on the electronic component but also on the solder connection portion, so that the durability of the solder connection portion may be reduced.

  Therefore, in the present embodiment, the above-described problem is solved as follows. FIG. 7 is a diagram schematically showing a cross section taken along the line AA of FIG. In the present embodiment, the soft layer 9 and the hard layer 10 are provided between the microcomputer 4, the control circuit 7, the electronic component 8 and the housing 302 mounted on the substrate 1. In FIG. 7, description will be made assuming that the microcomputer 4 and the electronic component 8 exist in the cross section taken along the line AA in FIG. 3.

  The hard layer 10 is a buffer layer provided to suppress the resistance force received from the housing resin that flows during injection molding, the transmission of shrinkage distortion of the housing resin, and the heat transfer from the high-temperature housing resin. It is. As shown in FIG. 7, the hard layer 10 is mounted on the front surface 1a of the substrate 1, and the upper surface is covered with the soft layer 9, as will be described later, the electronic component 8, and the hard layer 10 not shown in FIG. The illustrated control circuit 7 is covered from above. For convenience of explanation, the upper part in FIG. 7 is the upper direction, and the lower part is the lower direction.

  The soft layer 9 is a buffer layer provided to suppress the transmission of shrinkage distortion of the housing resin that cannot be suppressed by the hard layer 10 and to suppress heat transfer from the high-temperature housing resin together with the hard layer 10. is there. As shown in FIG. 7, the soft layer 9 covers the upper surface of the microcomputer 4, the electronic component 8, and the control circuit 7 not shown in FIG.

  Desirably, the elastic coefficient of the hard layer 10 is higher than the elastic coefficient of the housing 302, and the elastic coefficient of the soft layer 9 is lower than the elastic coefficient of the housing 302. That is, as described above, the role of the hard layer 10 is to suppress the transmission of the resin shrinkage strain of the housing 302. Therefore, the higher the rigidity of the hard layer 10 than the housing 302, the higher the effect of suppressing the shrinkage strain of the housing 302.

  On the other hand, since the role of the soft layer 9 is to relieve the shrinkage distortion of the housing 302 that could not be completely suppressed by the hard layer 10 by the deformation of the soft layer 9, the effect is improved as the soft layer 9 is easily deformed with low rigidity. high. For example, the housing 302 is made of a thermoplastic resin such as PBT, the soft layer 9 is made of a low-rigidity silicone resin or urethane resin, and the hard layer 10 is made of a glass-filled epoxy resin or the like. Satisfy the relationship. In addition, the structure of each member is applicable also with combinations other than the material shown above.

  Further, from the viewpoint of suppressing heat transfer from the high-temperature housing resin, it is desirable that the soft layer 9 and the hard layer 10 have a low thermal conductivity. However, even if the thermal conductivity is not low, the soft layer 9 and the hard layer 10 Since the components are separated from the high-temperature housing resin only by being provided, there is an effect of suppressing heat transfer.

  In the present embodiment, the housing 302 is manufactured as follows. First, as shown in FIG. 8, the soft layer 9 is provided on the substrate 1 as shown in FIG. 5 on which the sensors 3, 5, 6 and the microcomputer 4 are mounted. FIG. 8 is a view of the front surface 1a of the substrate 1 after the soft layer 9 is installed. In the present embodiment, the soft layer 9 is provided on the upper surface of the microcomputer 4, the control circuit 7, and the electronic component 8, that is, the surface opposite to the surface facing the front surface 1 a of the substrate 1. In order to provide the soft layer 9, for example, various methods such as a method of curing an ultraviolet curable resin with ultraviolet rays, a method of forming by hot melt molding, or a 3D printer can be used.

  In FIG. 8, as an example, the soft layer 9 is provided on the upper surfaces of all the components 4, 7, 8 mounted on the front surface 1 a of the substrate 1 except for the flow rate detection unit 3. The soft layer 9 should just be provided in the upper surface of the above components. In addition, by providing the soft layer 9 on the upper surface of each of the parts 4, 7, and 8 having the largest area in each of the parts 4, 7, and 8 and the distance from the housing 302, the transmission could not be suppressed by the hard layer 10. The shrinkage distortion of the housing 302 can be efficiently reduced by the soft layer 9.

  Thereafter, the hard layer 10 is provided. FIG. 9 is a view of the front surface 1a of the substrate 1 after the hard layer 10 is installed. The hard layer 10 is provided so as to cover the microcomputer 4, the electronic component 8, and the soft layer 9. That is, the hard layer 10 is on the soft layer 9, on the peripheral surface of the microcomputer 4 and the electronic component 8 where the soft layer 9 is not provided, and on the entire surface 1 a of the substrate 1 on which the microcomputer 4 and the electronic component 8 are not mounted. Is provided. The hard layer 10 is formed thick at a portion of the substrate 1 where the microcomputer 4 and the electronic component 8 are not disposed, and the upper surface thereof is formed to be a substantially flat surface. The flow rate detector 3 is not covered with the hard layer 10 because it needs to be exposed for measurement. As in the case of the soft layer 9, the hard layer 10 can be provided using various methods such as a method of curing an ultraviolet curable resin with ultraviolet rays, a method of forming by hot melt molding, or a 3D printer.

  In the present embodiment, since the microcomputer 4, the control circuit 7, and the electronic component 8 are mounted only on the front surface 1 a of the substrate 1, the soft layer 9 and the hard layer are mounted only on the front surface 1 a of the substrate 1. Layer 10 is provided. When double-sided mounting is performed by mounting an electronic component or the like on the back surface 1b, the soft layer 9 is provided on the electronic component or the like on the back surface 1b covered with the back surface portion 307 of the housing 302. It may be covered. However, since the pressure sensor 5 and the humidity sensor 6 need to be exposed for sensing, they are not covered with the hard layer 10. Moreover, since the board | substrate side connection part 12 connects with the connector side connection part 11 and the wire 13 after formation of the housing 302 by a resin mold, it is not covered with the hard layer 10.

  After providing the hard layer 10, the housing 302 is formed as shown in FIGS. 3 and 4, for example, by setting the substrate 1 in an injection mold and performing injection molding. Thereafter, the connector side connecting portion 11 and the board side connecting portion 12 are connected by the wire 13, and the front cover 303 and the back cover 304 are welded to the housing 302 by, for example, laser irradiation, thereby completing the flow sensor 300. Let

The flow sensor 300 of the present embodiment has the following operational effects.
(1) The upper surfaces of the components 4, 7, 8 mounted on the substrate 1 are covered with the soft layer 9, and the hard layer 10 is interposed between the soft layer 9 and the housing 302. Thereby, the hard layer 10 suppresses the resistance force received from the housing resin that flows during the injection molding and the transmission of the shrinkage strain of the housing resin, and the soft layer 9 suppresses the shrinkage strain of the housing resin that cannot be suppressed by the hard layer 10. Deform and absorb. Therefore, since the external force acting on each of the components 4, 7, and 8 after molding the housing 302 or after molding the housing 302 can be suppressed, the cost of the flow sensor 300 can be reduced while preventing the detection accuracy of the flow sensor 300 from being lowered.

  In addition, since the soft layer 9 and the hard layer 10 are interposed between the housing 302 and the parts 4, 7, and 8, heat to the parts 4, 7, and 8 when the housing 302 is molded from a thermoplastic resin. The transmission can be suppressed, the deterioration of the durability of the solder connection portion can be prevented, and the durability of the flow sensor 300 can be improved.

(2) Since the hard layer 10 directly contacts the substrate 1 and covers the substrate 1, the rigidity of the hard layer 10 is reinforced by the rigidity of the substrate 1, and the shrinkage distortion of the housing resin is transmitted to the components 4, 7, and 8. Can be efficiently suppressed. Therefore, the volume of the hard layer 10 can be suppressed, which contributes to the cost reduction of the flow sensor 300.

(3) The elastic coefficient of the hard layer 10 is higher than the elastic coefficient of the housing 302, and the elastic coefficient of the soft layer 9 is lower than the elastic coefficient of the housing 302. Since the external force acting on each of the parts 4, 7, and 8 after 302 molding can be efficiently suppressed, the cost of the flow sensor 300 can be reduced while preventing the accuracy of the flow sensor 300 from being lowered.

(4) The soft layer 9, the hard layer 10, and the housing 302 are provided so that the flow rate detection unit 3, the pressure sensor 5, and the humidity sensor 6 that must be exposed for sensing are exposed. Thereby, since the part which needs protection can be protected reliably, the reliability of the flow sensor 300 can be improved.

(5) When electronic components are mounted on the substrate 1 at a high density, the electronic components occupy the substrate 1, so that it is difficult to secure a fixed portion to the mold when the housing 302 is injection molded. Therefore, as described above, the electronic components on the substrate 1 are covered with the soft layer 9 and the hard layer 10, so that even if the electronic components are mounted on the substrate 1 with a high density, the soft layer 9 and the hard layer 10 The substrate 1 can be fixed by contacting the mold from above. Thereby, since the housing 302 can be formed by injection molding etc. with respect to the board | substrate 1 with which the electronic component was mounted with high density, the high performance and cost reduction of the flow sensor 300 can be compatible.

--- Second Embodiment ---
A second embodiment of the sensor device according to the present invention will be described with reference to FIGS. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment is different from the first embodiment mainly in that the soft layer 9 covers not only the upper surfaces of the components 4, 7, and 8, but also the side surfaces.

  10 and 11 are diagrams corresponding to FIG. 7 in the first embodiment, and are schematic views corresponding to the cross-sectional view taken along the line AA in FIG. 3. As shown in FIGS. 10 and 11, in the second embodiment, the upper surface and side surfaces of the microcomputer 4, the electronic component 8, and the control circuit 7 (not shown in FIGS. 10 and 11) are covered with the soft layer 9. . That is, in the present embodiment, each of the components 4, 7, 8 is covered with the soft layer 9 except for the surface facing the front surface 1 a of the substrate 1.

  In the example shown in FIG. 10, the soft layer 9 individually covers the components 4, 7, and 8, and the front surface 1 a of the substrate 1 between adjacent components is covered with the soft layer 9. The hard layer 10 is in contact. In the example shown in FIG. 11, the soft layer 9 has a uniform thickness between each of the parts 4, 7, 8 and adjacent parts, in accordance with the thickest part among the parts 4, 7, 8. The front surface 1a of the substrate 1 is covered.

The flow sensor 300 of the second embodiment has the following operational effects in addition to the operational effects of the first embodiment.
(1) The upper surface and the side surface of each component 4, 7, 8 were configured to be covered with the soft layer 9. Thereby, since each component 4,7,8 does not contact the hard layer 10 directly, the external force which acts on each component 4,7,8 at the time of the shaping | molding of the housing 302 or after the housing 302 shaping | molding can be suppressed efficiently. Therefore, the cost of the flow sensor 300 can be reduced while preventing the accuracy of the flow sensor 300 from being lowered.

(2) As shown in FIG. 10, each component 4, 7, and 8 is individually covered with the soft layer 9, and the hard layer 10 contacts the front surface 1a of the board | substrate 1 between adjacent components. By configuring, the rigidity of the hard layer 10 is reinforced by the rigidity of the substrate 1. Thereby, it can suppress efficiently that the shrinkage distortion of housing resin is transmitted to each components 4, 7, and 8 and the volume of the hard layer 10 can be suppressed, Therefore It contributes to the cost reduction of the flow sensor 300.

(3) As shown in FIG. 11, in accordance with the thickest part among the parts 4, 7, and 8, each part 4, 7, 8 and a part between adjacent parts with a uniform thickness. By configuring the front surface 1a of the substrate 1 to be covered with the soft layer 9, the soft layer 9 can be easily installed. Thereby, the cost concerning installation of the soft layer 9 can be suppressed, and it contributes to the cost reduction of the flow sensor 300.

--- Third embodiment ---
A third embodiment of the sensor device according to the present invention will be described with reference to FIGS. In the following description, the same components as those in the first or second embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first or second embodiment. In the present embodiment, the mold region of the housing 302 mainly made of resin is different from the first and second embodiments.

  12 and 13 are diagrams corresponding to FIG. 7 in the first embodiment, and are schematic views corresponding to the cross-sectional view taken along the line AA in FIG. 3. As shown in FIGS. 12 and 13, in the third embodiment, when the substrate 1 is viewed from above, the resin of the housing 302 does not exist in a region that overlaps the mounting region of the components 4, 7, and 8. The hard layer 10 is exposed. That is, in the present embodiment, the soft layer 9 and the hard layer 10 are provided above the components 4, 7, and 8, but the resin of the housing 302 does not exist. The housing 302 is provided at least on both sides of the substrate 1 in the X direction.

  As the amount of resin in the housing 302 above the parts 4, 7, and 8 increases, and as the distance from the housing 302 above the parts 4, 7, and 8 decreases, the parts 4, 7, and 8 move toward the housing 302. Easy to receive resin shrinkage during molding. For this reason, if the housing 302 is not formed above each component 4, 7, and 8 like this Embodiment, the influence on the components 4, 7, 8 of the resin shrinkage force mentioned above can be reduced. As shown in FIG. 12, the housing 302 may be configured so that the resin of the housing 302 exists only at the periphery of the substrate 1, and as shown in FIG. The housing 302 may be configured so that the resin of the housing 302 exists.

  The structure of the soft layer 9 and the hard layer 10 shown in FIGS. 12 and 13 is the same as that shown in FIG. 11 in the second embodiment, but shown in FIG. 10 in the second embodiment. The same structure as that described above may be used.

  If the resin of the housing 302 does not exist above all the parts 4, 7, and 8 mounted on the front surface 1a of the substrate 1, the parts 4, 7, and 8 are mounted with high density. In this case, it is difficult to secure a bonding area between the substrate 1 and the housing 302. Therefore, the parts are preferentially given to the parts having high sensitivity to the above-described resin shrinkage force, or parts that are large and have a large influence on the parts themselves or the solder joints (for example, the microcomputer 4 and the control circuit 7). What is necessary is just to set it as the structure mentioned above which does not provide resin of the housing 302 above. As a result, it is possible to reduce both the influence of the above-described resin shrinkage force on the main parts and secure the fixing region of the housing 302.

The flow sensor 300 of the third embodiment has the following operational effects in addition to the operational effects of the first and second embodiments.
(1) When the substrate 1 is viewed from above the components 4, 7, and 8, the housing 302 is configured so that the resin of the housing 302 does not exist in the region where the components 4, 7, and 8 are present. As a result, the external force acting on the parts 4, 7, and 8 can be efficiently suppressed when the housing 302 is molded or after the housing 302 is molded, thereby reducing the cost of the flow sensor 300 while preventing the flow sensor 300 from being degraded. Can be planned.

(2) Since the amount of resin used in the housing 302 can be reduced, the flow sensor 300 can be reduced in weight.

--- Fourth embodiment ---
A fourth embodiment of the sensor device according to the present invention will be described with reference to FIG. In the following description, the same components as those in the first to third embodiments are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first to third embodiments. In the present embodiment, when the substrate 1 is viewed from above, the housing 302 in the region that overlaps the mounting region of the components 4, 7, and 8 is thinner than the other regions. Different from the third embodiment.

  14 is a diagram corresponding to FIG. 7 in the first embodiment, and is a schematic diagram corresponding to the cross-sectional view taken along the line AA in FIG. 3. As shown in FIG. 14, in the fourth embodiment, when the substrate 1 is viewed from above, the thickness of the housing 302 in the region overlapping the mounting region of the components 4, 7, and 8 is larger than that in the other regions. Is also thin.

  For example, in the third embodiment described above, when the housing 302 is formed, the substrate 1 is set and clamped in a mold, but the upper surface of the hard layer 10 that is the outermost layer is in contact with the mold. There are dimensional tolerances in the base 1, the soft layer 9, and the hard layer 10. In the third embodiment described above, the mold used when forming the housing 302 is the base 1, the soft layer 9, and the hard layer. The thickness of 10 is made to the smallest dimension. Therefore, even if the thicknesses of the base 1, the soft layer 9, and the hard layer 10 are within the dimensional tolerances, the thickness of the portion sandwiched between the molds may be larger than the mold dimensions. Therefore, when the board | substrate 1 is clamped by the metal mold | die, there exists a possibility that compressive force may act on each components 4, 7, and 8 undesirably.

  Therefore, the mold used when forming the housing 302 in the present embodiment is configured such that a gap is formed between the outermost hard layer 10 when the substrate 1 is sandwiched. By configuring the mold in this way, even if the substrate 1 is sandwiched between the molds, there is no possibility that an undesired compressive force acts on the components 4, 7, and 8. When the housing 302 is formed using this mold, as shown in FIG. 14, the thin housing 302 is formed in the region overlapping with the mounting region of the components 4, 7, and 8, but the thickness is small. Therefore, the influence of the resin shrinkage force when molding the housing 302 is smaller than that of the first and second embodiments described above.

The flow sensor 300 according to the fourth embodiment has the following functions and effects in addition to the functions and effects of the first to third embodiments.
(1) When the substrate 1 is viewed from above the components 4, 7, and 8, the resin in the housing 302 is thinner in the region where the components 4, 7, and 8 are present than in the other regions. The housing 302 was configured as described above. As a result, the external force acting on the parts 4, 7, and 8 can be efficiently suppressed when the housing 302 is molded or after the housing 302 is molded, thereby reducing the cost of the flow sensor 300 while preventing the flow sensor 300 from being degraded. Can be planned.

(2) When the substrate 1 is sandwiched between the molds for forming the housing 302, a mold configured such that a gap is formed between the outermost hard layer 10 can be used. Since it is not necessary to increase the dimensional accuracy more than necessary, the cost of the mold can be suppressed, and the cost of the flow sensor 300 can be reduced.

--- Fifth embodiment ---
A fifth embodiment of the sensor device according to the present invention will be described with reference to FIGS. In the following description, the same components as those in the first to fourth embodiments are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first to fourth embodiments. In the present embodiment, the first to fourth points are mainly configured in such a manner that a groove 14 is provided on the front surface 1a of the substrate 1 and the soft layer 9 or the hard layer 10 is also provided in the groove 14. This is different from the embodiment.

  FIGS. 15 and 16 are diagrams corresponding to FIG. 7 in the first embodiment, and are schematic views corresponding to the cross-sectional view taken along the line AA in FIG. 3. As shown in FIGS. 15 and 16, in the fifth embodiment, a groove 14 is provided on the front surface 1 a of the substrate 1. In the example shown in FIG. 15, since the soft layer 9 is also formed in the groove 14, the bonding strength between the substrate 1 and the soft layer 9 is improved by the anchor effect. In the example shown in FIG. 16, since the hard layer 10 is also formed in the groove 14, the bonding strength between the substrate 1 and the hard layer 10 is improved by the anchor effect.

  The flow sensor 300 according to the fifth embodiment provides the following operational effects in addition to the operational effects of the first to fourth embodiments. That is, since the groove 14 is provided on the front surface 1a of the substrate 1 and the soft layer 9 or the hard layer 10 is also provided in the groove 14, the resin of the housing 302 is molded by, for example, injection molding. Even if a high injection pressure is applied, the soft layer 9 and the hard layer 10 do not come off the substrate 1. Therefore, the reliability of the flow sensor 300 can be improved.

--- About effects of each embodiment ---
Hereinafter, as an example, in the second embodiment shown in FIG. 11 and the third embodiment shown in FIG. 12, the effect of suppressing the shrinkage distortion of the housing resin and the heat transfer during injection molding are suppressed. About the effect, the result calculated | required analytically using the predetermined model is demonstrated. In this analysis, analysis was performed by a computer simulation software using a known resin molding analysis method.

  FIG. 17 is a diagram illustrating an analysis model in a conventional structure example in which the soft layer 9 and the hard layer 10 are not provided. In FIG. 17, reference numeral 16 denotes a substrate area, 15 denotes an electronic component area such as a microcomputer or a control circuit, and 17 denotes a housing area. As an example, as shown in FIG. 17, the thickness of the region 16 of the substrate is 0.5 mm, the width in the X direction is 15 mm, and the width in the Y direction is 15.0 mm, the same as in the X direction. The thickness of the region 15 of the electronic component was 0.5 mm, the width in the X direction was 3.0 mm, and the width in the Y direction was 3.0 mm, the same as in the X direction. The electronic component region 15 was placed at the center of the substrate region 16. The thickness of the housing region 17 was 1.5 mm, the width in the X direction was 15.0 mm, and the width in the Y direction was 15.0 mm, the same as in the X direction. However, the region overlapping with the electronic component region 15 was excluded from the housing region 17.

  FIG. 18 is a diagram showing an analysis model in the second embodiment shown in FIG. In this analysis model, a soft layer region 18 and a hard layer region 19 are set in addition to a substrate region 16, an electronic component region 15 such as a microcomputer and a control circuit, and a housing region 17 as shown in FIG. To do. The substrate region 16 and the electronic component region 15 were set in the same manner as the analysis model in the conventional structure example. A soft layer region 18 is provided around the XY plane on the upper side of the substrate region 16 in the Z direction and the region 15 of the electronic component, the thickness is 0.7 mm, the width in the X direction is 15 mm, and the width in the Y direction is X. Same as the direction, it was 15.0mm. However, the area overlapping the area 15 of the electronic component was excluded from the area 18 of the soft layer.

  Further, a hard layer region 19 is installed on the XY plane on the upper side of the soft layer region 18 in the Z direction, the thickness is 0.3 mm, the width in the X direction is 15 mm, and the width in the Y direction is 15.0 mm, which is the same as the X direction. did. Further, the housing region 17 is installed on the XY plane on the upper side in the Z direction of the hard layer region 19, and the thickness thereof is set to 0.5 mm, and the upper side in the Z direction on the housing region 17 from the XY plane on the upper side in the Z direction of the substrate region 16 The distance on the XY plane was set to 1.5 mm, which is the same as the analysis model of the conventional structure example shown in FIG. The width of the housing region 17 in the X direction was 15 mm, and the width in the Y direction was 15.0 mm, the same as in the X direction.

  FIG. 19 is a diagram showing an analysis model in the third embodiment shown in FIG. This analysis model has the same configuration as the analysis model in FIG. 11 of the second embodiment shown in FIG. 18 except for the region 17 of the housing. The housing region 17 was installed except for the region above the electronic component region 15.

As physical property data, a printed circuit board is assumed as an example in the board region 16, and an elastic modulus of 20 GPa, a Poisson's ratio of 0.2, a linear expansion coefficient of 12.0 × 10 ⁻⁶ , a thermal conductivity of 0.62 W / mK, a specific heat of 950 J / kgK, a density 2000kg / m ³ was entered. As an example, the electronic component region 15 is assumed to be a silicon chip, with an elastic modulus of 188 GPa, a Poisson's ratio of 0.18, a linear expansion coefficient of 2.3 × 10 ⁻⁶ , a thermal conductivity of 150 W / mK, a specific heat of 712 J / kgK, and a density of 2330 kg / m ^3. Was entered. As an example, the soft layer region 18 is assumed to be urethane, with an elastic modulus of 0.2 GPa, a Poisson's ratio of 0.2, a linear expansion coefficient of 200 × 10 ⁻⁶ , a thermal conductivity of 0.15 W / mK, a specific heat of 1900 J / kgK, and a density of 1180 kg / m. ³ was entered.

As an example, the hard layer region 19 is assumed to be made of epoxy resin containing glass filler, elastic modulus 27 GPa, Poisson's ratio 0.3, linear expansion coefficient 8.0 × 10 ⁻⁶ , thermal conductivity 0.3 W / mK, specific heat 1100 J / kgK, A density of 1850 kg / m ³ was entered. As an example, assuming that the region 17 of the housing is polybutylene terephthalate (PBT) containing glass filler, the elastic modulus is 7.4 GPa, the Poisson's ratio is 0.2, the linear expansion coefficient is 50 × 10 ⁻⁶ , the thermal conductivity is 0.3 W / mK, Specific heat 1200 J / kgK, enter the density 1300 kg / m ^3.

  As an analysis condition, in the analysis related to the effect of suppressing the transmission of shrinkage strain of the housing resin, a heat shrinkage load having a temperature change ΔT = −170 ° C. is applied to the region of the housing resin, and the lower surface of the substrate on the central axis as shown in FIGS. Was defined as the restraint point. On the other hand, in the analysis of the temperature of the electronic component boundary surface regarding the heat transfer suppression effect at the time of injection molding, the initial temperature of the housing resin region is set to 250 ° C. of the resin melting temperature, and the temperature of the lower surface of the substrate region is The temperature boundary was set to be ℃.

  FIG. 20 is a graph showing an analysis regarding the effect of suppressing the shrinkage strain of the housing resin. As shown in FIG. 20, (a) as compared with the conventional structure example, (b) when a soft layer and a hard layer are provided around the electronic component as in the second embodiment, the load is applied to the electronic component. The stress reduction effect is -68%. (B) A housing structure in which an area overlapping with an electronic component on the XY plane is removed from the second embodiment. (C) In the case of the third embodiment, (a) Compared to the conventional structure example, the electronic component is loaded. The stress reduction effect was -79%.

  FIG. 21 is a graph showing the analysis result of the temperature of the electronic component boundary surface related to the effect of suppressing heat transfer during injection molding. In FIG. 21, the highest achieved temperature at the electronic component boundary surface is plotted on the vertical axis and evaluated. As shown in FIG. 21, (a) in the conventional structure example, since the housing resin is in direct contact with the solder, the maximum temperature reached at the electronic component interface is 250 ° C., the same as the melting resin temperature. On the other hand, in (b) Embodiment 2 and (c) Embodiment 3, the soft layer and the hard layer having low thermal conductivity are sandwiched between the housing resin and the electronic component, so that the maximum reach of each electronic component interface is achieved. The temperatures are 101 ° C. and 91 ° C., which is sufficiently lower than the melting temperature of 220 to 260 ° C., and the thermal load on the solder can be reduced.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say. The present invention can be applied to the structure of a sensor device in which a substrate on which electronic components such as a flow rate detection unit, a control circuit unit, a pressure sensor, a humidity sensor, and a microcomputer are mounted is joined to a housing (housing). It is. For example, the present invention can be applied not only to the flow rate sensor but also to other types of sensor devices that adopt a similar module structure.

In the above description, the resin of the housing 302 is in direct contact with the substrate 1 at least partially, but the present invention is not limited to this. For example, as shown in FIG. 22, the hard layer 10 may be interposed between the resin in the housing 302 and the substrate 1, and the resin in the housing 302 may not be in direct contact with the substrate 1.
The above-described embodiments and modifications may be combined.

DESCRIPTION OF SYMBOLS 1 Board | substrate, 3 Flow volume detection part, 4 Microcomputer, 5 Pressure sensor, 6 Humidity sensor, 7 Control circuit, 8 Electronic component, 9 Soft layer, 10 Hard layer, 300 Flow rate sensor, 301 Case, 302 Housing, 310 Measurement part

Claims (9)

A substrate on which electronic components constituting a flow rate detection unit and a control circuit for controlling the flow rate detection unit are mounted;
A resin housing covering the substrate;
A soft layer covering at least the upper surface of the electronic component mounted on the substrate;
A hard layer interposed between the soft layer and the resin housing;
The resin housing is a sensor device in which at least a part of the hard layer is integrated with the hard layer and exposes the flow rate detection unit. The sensor device according to claim 1,
The said soft layer is a sensor apparatus which covers all the surfaces other than the surface which opposes the said board | substrate among the surfaces of the said electronic component. The sensor device according to claim 1 or 2,
The electronic component is mounted on one side of both sides of the substrate,
The hard layer is a sensor device that is in contact with the one surface of the substrate at a portion of the one surface of the substrate that is not covered with the soft layer. The sensor device according to claim 2,
The electronic component is mounted on one side of both sides of the substrate,
The soft layer is a sensor device that covers all of the one surface of the substrate. The sensor device according to claim 1,
A sensor device in which the resin housing is not provided in a region where the electronic component is present when the substrate is viewed from above the electronic component. The sensor device according to claim 1,
When the substrate is viewed from above the electronic component, the region where the electronic component is present is a sensor device in which the resin housing is thinner than the other regions. In the sensor device according to any one of claims 1 to 6,
The substrate has a groove formed on the one surface;
A sensor device in which at least one of the soft layer and the hard layer is also formed in the groove. In the sensor device according to any one of claims 1 to 6,
A pressure sensor for detecting the pressure of the fluid to be detected and a humidity sensor for detecting the humidity of the fluid to be detected are further mounted on the substrate.
The pressure sensor and the humidity sensor are exposed sensor devices. In the sensor device according to any one of claims 1 to 6,
The elastic modulus of the soft layer is lower than the elastic modulus of the resin housing,
A sensor device in which an elastic coefficient of the hard layer is higher than an elastic coefficient of the resin housing.

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