JP2013029376A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect boding wire even against sudden pressure fluctuation while miniaturizing constitution in a pressure sensor which measures pressure of measurement fluid containing liquid.SOLUTION: A sensor chip 30 for pressure detection is arranged on a recess bottom surface 24a of a first housing 20, and the sensor chip 30 is connected to a terminal 40 held by the first housing 20 via bonding wire 50. The sensor chip 30, an end 41 of the terminal 40, and the bonding wire 50 are protected by a protection member 60. The protection member 60 has: an elastic member 61 in which liquid rubber is hardened; and a high hardness member 62 which consists of a material with a Young's modulus higher than that of the elastic member 61, at least a part of which is embedded and held in the elastic member 61. With the elastic member 61, at least a part of the sensor chip 30, the end 41 of the terminal 40, and the bonding wire 50 are coated, and the high hardness member 62 is arranged at an upper part of a diaphragm 31.

Description

  In the present invention, the sensor chip is disposed on the bottom surface of the recess of the first housing and is electrically connected to the terminal held by the first housing via the bonding wire, and is exposed in the recess of the sensor chip and the terminal. The present invention relates to a pressure sensor configured to transmit the pressure of a measurement fluid to a diaphragm through a protective member disposed in a recess so as to cover the end portion and the bonding wire.

  A pressure sensor that measures the pressure of a measurement fluid (liquid or gas-liquid mixture) containing liquid is mounted on a vehicle, for example, and exposed to liquid such as engine oil, fuel, and air conditioner refrigerant. And a function capable of protecting bonding wires. In addition, since a liquid is included as a measurement fluid, a liquid capable of performing high-pressure measurement (for example, MPa order) is required. As such a pressure sensor, for example, one having a configuration shown in Patent Document 1 is known.

  In Patent Document 1, a sensor element (sensor chip) is disposed on a bottom surface of a concave portion of a connector case (first housing), and is electrically connected to a terminal (terminal) held by the connector case via a bonding wire. Yes. A metal diaphragm is disposed so as to close the concave portion of the connector case, and a pressure detection chamber is formed by the concave portion and the metal diaphragm. The pressure detection chamber (recessed portion) is filled with oil, and the oil covers the sensor element, the end exposed in the recessed portion of the terminal, and the bonding wire.

  Note that a ring weld pressed by the metal diaphragm is fixed to the housing (second housing) assembled to the connector case by welding all around the metal diaphragm, and the metal diaphragm is fixed to the housing via the ring weld. Further, the internal space of the housing formed in a cylindrical shape by the metal diaphragm is divided into a housing space for housing the connector case and an introduction space for introducing the measurement fluid into the concave portion of the connector case disposed in the housing space. Has been.

  In this pressure sensor, the pressure of the measurement fluid is transmitted to the sensor chip via a protective member made of a metal diaphragm and oil. In addition, the sensor chip and the bonding wire are protected from the engine oil, fuel, air conditioner refrigerant, and the like by the protective member.

JP 2010-85307 A

  As described above, in the pressure sensor configured to transmit the pressure of the measurement fluid to the sensor chip via the protective member made of the metal diaphragm and the oil, the volume of the oil changes according to the change in the ambient temperature. The volume of the pressure detection chamber also changes. In particular, when the ambient temperature becomes high, the volume of the oil increases due to thermal expansion or the like, and thus the volume of the pressure detection chamber increases.

  For this reason, in order to suppress the change in the internal pressure of the pressure detection chamber accompanying the change in the volume of the pressure detection chamber, that is, the decrease in pressure detection accuracy, the metal diaphragm must be provided so as to be greatly deformable. That is, the diameter of the deformable portion inside the fixed portion fixed by the ring weld has to be made larger, and it is difficult to reduce the size of the physique.

  Further, the sensor chip, the end portion exposed in the concave portion of the terminal, and the bonding wire are covered with oil which is a liquid. For this reason, when the pressure of the measurement fluid suddenly rises due to the pulsation of the pump that sends out the measurement fluid, the oil flows greatly and the bonding wire is damaged.

  In view of the above problems, an object of the present invention is to provide a pressure sensor that measures the pressure of a measurement fluid containing a liquid, and can protect a bonding wire against sudden pressure fluctuations while reducing the size of the body.

In order to achieve the above object, the pressure sensor according to claim 1 comprises:
A first housing (20) having a recess (24);
A diaphragm (31) formed on the one surface (30a) side and having gauge resistance, and an external connection pad (33) formed on the one surface (30a) in the peripheral region (32) surrounding the diaphragm (31). And a sensor chip (30) disposed on the bottom surface of the recess (24a) such that the back surface (30b) opposite to the one surface (30a) faces the bottom surface (24a) of the first housing (20). ,
The first housing (20) is held by the first housing (20), one end (41) is exposed in the recess (24), and the other end (42) is different from the recess (24). An external connection terminal (40) exposed to the outside,
A bonding wire (50) for electrically connecting the end (41) exposed in the recess (24) of the terminal (40) and the pad (33) of the sensor chip (30);
A sensor chip (30), an end (41) exposed in the recess (24) of the terminal (40), and a protective member (60) covering the bonding wire (50),
The pressure sensor is configured to transmit the pressure of the measurement fluid including the liquid to the sensor chip (30) via the protective member (60).

The protective member (60) is formed using an elastic member (61) obtained by curing liquid rubber and a material having a Young's modulus higher than that of the elastic member (61). A high-hardness member (62) partially embedded and held by the elastic member (61),
The elastic member (61) covers at least part of the sensor chip (30), the end (41) exposed in the recess (24) of the terminal (40), and the bonding wire (50),
The high hardness member (62) is arranged above the diaphragm (31).

  In the present invention, the end portion (41) exposed in the recess (24) of the sensor chip (30) and the terminal (40) by the protective member (60) having the elastic member (61) and the high hardness member (62). And the bonding wire (50) can be protected from liquids. Moreover, since oil (liquid) is not used as a protection member (60) conventionally and a metal diaphragm is unnecessary, a physique can also be reduced in size.

  Further, the elastic member (61) formed by curing the liquid rubber has at least a part of the sensor chip (30), the end (41) exposed in the recess (24) of the terminal (40), and the bonding wire. (50) is coated. For this reason, even if the pressure of the measurement fluid suddenly increases due to the pulsation of the pump that sends out the measurement fluid, the energy received from the measurement fluid can be attenuated by the elastic member (61). Therefore, the bonding wire (50) can be particularly protected against sudden pressure fluctuations.

  Moreover, the protection member (60) has the high hardness member (62) arrange | positioned above the diaphragm (31). The high hardness member (62) has a smaller amount of energy attenuation than the elastic member (61). For this reason, pressure can be efficiently transmitted to the diaphragm (31) as compared with the configuration in which the elastic member (61) is arranged instead of the high hardness member (62).

  As described above, according to the present invention, in the pressure sensor that measures the pressure of the measurement fluid containing the liquid, the bonding wire can be protected against sudden pressure fluctuations while reducing the size of the body.

As claimed in claim 2,
The high hardness member (62) is preferably exposed to the outside from the surface (61a) opposite to the surface in contact with the bottom surface (24a) of the recess in the elastic member (61).

  According to this, the high hardness member (62) is completely covered with the elastic member (61), and the pressure can be efficiently transmitted to the diaphragm (31) as compared with a configuration in which the high hardness member (62) is not exposed to the outside.

Furthermore, as described in claim 3,
The high hardness member (62) may project outward from the surface (61a) of the elastic member (61).

  According to this, when the protective member (60) is formed, the liquid rubber is filled in the concave portion (24) while holding the portion protruding from the elastic member (61) of the high hardness member (62), and the curing process is performed. Therefore, the high-hardness member (62) can be easily arranged with respect to the elastic member (61).

As claimed in claim 4,
More preferably, the high hardness member (62) is in contact with the diaphragm (31) of the sensor chip (30). According to this, a pressure can be efficiently transmitted to a diaphragm (31) compared with the structure where an elastic member (61) exists between a diaphragm (31) and a high-hardness member (62).

As claimed in claim 5,
The area of the high hardness member (62) in the direction along the one surface (30a) of the sensor chip (30) is more than the end portion (62a) contacting the diaphragm (31) of the sensor chip (30). It is preferable that the end (62b) opposite to is larger.

  According to this, the pressure which a diaphragm (31) receives can be raised by the high hardness member (62). That is, sensor sensitivity can be increased.

  Further, the length of the leak path generated from the surface (61a) of the elastic member (61) to the sensor chip (30) may be increased along the interface between the high hardness member (62) and the elastic member (61). it can.

Furthermore, as described in claim 6,
The high hardness member (62) is preferably formed in a spindle shape.

  According to this, compared with a step-like high hardness member (62) etc., the viscous resistance which acts between elastic members (61) can be made small, and this can raise sensor sensitivity more.

As claimed in claim 7,
The high hardness member (62) is preferably disposed at a position that does not overlap the bonding wire (50) in the direction along the one surface (30a) of the sensor chip (30).

  According to this, since the elastic member (61) can be thickened by the absence of the high-hardness member (62), the energy received from the measurement fluid by the elastic member (61) even if the pressure of the measurement fluid suddenly increases. Can be attenuated more effectively.

As claimed in claim 8,
In the direction along one surface (30a) of the sensor chip (30), it is preferable that the center of the high hardness member (62) and the center of the diaphragm (31) coincide.

  According to this, the displacement amount of the diaphragm (31) can be increased as compared with the configuration in which the center of the high hardness member (62) and the center of the diaphragm (31) are shifted. Therefore, the sensor sensitivity can be further increased.

As claimed in claim 9,
The first housing (20) is farther from the bottom surface of the recess (24a) than the bonding wire (50) in the direction perpendicular to the one surface (30a) of the sensor chip (30), and is in the elastic member (61). A support portion (26) positioned between the surface (61a) opposite to the surface in contact with the recess bottom surface (24a) and the bonding wire (50);
The protection member (60) is formed using a material having a higher Young's modulus than the elastic member (61), does not contact the high hardness member (62), and covers the bonding wire (50). It is good also as a structure which has the cover (63) fixed to 26).

  According to this, when the pressure of the measurement fluid suddenly increases, a part of the energy received by the protection member (60) from the measurement fluid is transferred to the first housing via the cover (63) and the support portion (26). You can escape to (20). Thereby, a bonding wire (50) can be protected more effectively.

As claimed in claim 10,
As the high hardness member (62), a member formed using a ceramic material or a metal material can be adopted.

In addition, each of the above-described inventions as described in claim 11
As a space inside the cylinder, which is formed in a cylindrical shape, an accommodation space for accommodating the recess (24) of the first housing (20), and a recess (24) of the first housing (20) disposed in the accommodation space And a second housing (70) having an introduction space for introducing a measurement fluid.
The first housing (20) has an annular fixed surface (20a) surrounding the recess (24) and a groove (25) formed along the annular shape on the fixed surface (20a).
The second housing (70) has an opposing surface (70a) facing the fixed surface (20a) as its inner wall surface,
The annular seal member (80) disposed in the groove (25) is suitable for a structure in close contact with the fixed surface (20a) of the first housing (20) and the facing surface (70a) of the second housing (70). is there.

In this case, as described in claim 12,
In a direction perpendicular to one surface (30a) of the sensor chip (30), the elastic member (61) is disposed to a position farther from the recess bottom surface (24a) than the facing surface (70a) of the second housing (70). It is good to have a configuration.

  According to this, the sealing member (80) can also be protected by the protection member (60). For this reason, an inexpensive thing can also be employ | adopted as a sealing member (80).

It is sectional drawing which shows schematic structure of the pressure sensor which concerns on 1st Embodiment. It is the figure which expanded the area | region II enclosed with the dashed-two dotted line in FIG. It is a figure which shows the positional relationship of a sensor chip and a high hardness member. It is sectional drawing which shows the modification of a protection member. It is sectional drawing which shows the modification of a protection member. It is sectional drawing which shows schematic structure of the pressure sensor which concerns on 2nd Embodiment, and respond | corresponds to the said FIG. It is sectional drawing which shows schematic structure of the pressure sensor which concerns on 3rd Embodiment, and respond | corresponds to the said FIG. It is a figure which shows the positional relationship of a sensor chip and a high hardness member. It is a top view which shows the 1st housing with which the sensor chip was mounted among the pressure sensors which concern on 4th Embodiment, (a) is a state without a cover, (b) has shown the state which fixed the cover. Note that both (a) and (b) show the state before the protective member is arranged. It is sectional drawing which shows schematic structure of the pressure sensor which concerns on 4th Embodiment. This sectional view is a sectional view taken along line XX in FIG. 9 and corresponds to FIG. 2 described above. It is sectional drawing which shows schematic structure of the pressure sensor which concerns on 4th Embodiment. This sectional view is a sectional view taken along line XI-XI in FIG. 9 and corresponds to FIG. It is sectional drawing which shows the modification of a protection member. It is sectional drawing which shows the other modification of a pressure sensor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is provided to the part which is mutually the same or equivalent in each figure below.

(First embodiment)
The pressure sensor according to the present embodiment is used for measuring the pressure of a measurement fluid containing a liquid (pressure of 1 MPa or more). Specifically, it is mounted on a vehicle and used for measuring the refrigerant pressure in the refrigerant piping of the air conditioner, the oil pressure of the CVT, the fuel pressure, and the like.

  As shown in FIGS. 1 to 3, the pressure sensor 10 includes a first housing 20 having a recess 24, a pressure measuring sensor chip 30 disposed in the recess 24 of the first housing 20, and the first housing 20. A terminal 40 as an external connection terminal held on the substrate, a bonding wire 50 for electrically connecting the sensor chip 30 and the terminal 40, and a protection covering the sensor chip 30, a part of the terminal 40, and the bonding wire 50. A member 60 is provided. The present embodiment further includes a second housing 70 that is assembled to the first housing 20 and guides the measurement fluid to the recess 24, and an O-ring 80 as a seal member.

  In the pressure sensor 10 configured as described above, the present embodiment is characterized by the protective member 60. Therefore, a part of the pressure sensor 10 excluding the protective member 60 will be described first.

  The first housing 20 is formed by injection molding a synthetic resin such as PPS or PBT, and has a recess 24 in which the sensor chip 30 is disposed. A terminal 40 is held in the first housing 20.

  In the present embodiment, a columnar enlarged diameter portion 21 accommodated in the second housing 70, a columnar small diameter portion 22 connected to the enlarged diameter portion 21 and having a smaller diameter than the enlarged diameter portion 21, and the small diameter portion 22 And a connector portion 23 that is connected to the opposite side of the enlarged diameter portion 21 and into which an external connector is fitted.

  An end surface of the enlarged diameter portion 21 opposite to the small diameter portion 22 forms one end surface 20a of the first housing 20, and a concave portion 24 is formed at a central portion of the end surface 20a. That is, the end surface 20a surrounds the recess 24 in an annular shape, and the end surface 20a corresponds to the fixed surface described in the claims. Hereinafter, the end surface 20a is referred to as a fixed surface 20a. The recess 24 has a planar circular shape, and a sensor chip 30 for pressure detection is disposed at the center position of the bottom surface 24 a of the recess 24.

  The sensor chip 30 is made of a semiconductor substrate such as silicon, and has a diaphragm 31 as a thin portion on one surface 30a side. The diaphragm 31 is formed by etching the semiconductor substrate from the back surface 30b side opposite to the one surface 30a. Further, on one surface 30a of the sensor chip 30, a gauge resistor (not shown) formed by diffusing impurities, for example, is formed in the diaphragm 31 portion. For example, four gauge resistors are provided, and constitute a bridge circuit (not shown).

  As described above, the sensor chip 30 of the present embodiment is configured as a semiconductor sensor chip. Specifically, the diaphragm 31 receives pressure, the diaphragm 31 is distorted (deformed) by the pressure, and the resistance value of the gauge resistance changes due to the piezoresistance effect. A signal corresponding to the distortion of the diaphragm 31, that is, a signal having a level corresponding to the applied pressure value is output by a bridge circuit made of a gauge resistor.

  In the present embodiment, not only a bridge circuit made of a gauge resistor but also a processing circuit for processing a signal output from the bridge circuit is formed (integrated) on the sensor chip 30. The signal processed by the processing circuit is output to the outside of the sensor chip 30 via the pad 33 formed in the peripheral region 32 surrounding the diaphragm 31 in the one surface 30a of the sensor chip 30. ing.

  The sensor chip 30 is fixed to the bottom surface 24 a of the recess 24 formed in the first housing 20 through a glass pedestal 34. Specifically, the pedestal 34 is bonded and fixed to the bottom surface 24 a of the recess 24, and the sensor chip 30 is anodically bonded to the pedestal 34 so that the back surface 30 b faces the pedestal 34. In this way, the sensor chip 30 is fixed to the first housing 20.

  The first housing 20 holds a plurality of terminals 40 as external connection terminals that electrically connect the sensor chip 30 to an external circuit or the like. The terminal 40 is formed by processing a metal material into a rod shape. In this embodiment, the terminal 40 is integrally formed with the first housing 20 as an insert part when the first housing 20 is formed.

  Each terminal 40 has one end 41 protruding from the bottom surface 24 a of the recess 24 and exposed in the recess 24, and the other end 42 exposed to the outside from the connector portion 23 of the first housing 20. Yes. Then, the end portion 41 exposed in the recess 24 in each terminal 40 and the corresponding pad 33 are electrically connected via the bonding wire 50.

  The second housing 70 is formed into a cylindrical shape using a metal material such as aluminum, and is formed with respect to the first cylindrical portion 71 that accommodates the enlarged diameter portion 21 of the first housing 20 and the concave portion 24 of the first housing 20. The second cylinder 72 for introducing the measurement fluid and the third cylinder 73 connecting the cylinders 71 and 72 are provided. The opening area of the first cylinder part 71 and the opening area of the second cylinder part 72 are substantially constant, respectively. Further, the opening area of the first cylinder portion 71 is larger than the opening area of the second cylinder portion 72. And the opening area of the 3rd cylinder part 73 which connects the cylinder parts 71 and 72 is so small that it distances from the sensor chip 30. FIG. A reference numeral 72 a shown in FIG. 1 is a pressure introduction hole formed in the second cylindrical portion 72 in order to guide the measurement fluid to the concave portion 24.

  The second housing 70 has a facing surface 70 a facing the fixed surface 20 a of the first housing 20 at the boundary between the first cylindrical portion 71 and the third cylindrical portion 73 as an inner wall surface. An annular groove 25 is formed on the fixed surface 20a of the first housing 20 so as to surround the recess 24, and an O-ring 80 for hermetically sealing the recess 24 is disposed in the groove 25. Yes. The O-ring 80 is in close contact with the bottom surface of the groove portion 25 of the first housing 20 and the facing surface 70a of the second housing 70, so that the fixed surface 20a of the first housing 20 and the second housing 70 face each other. A gap between the surface 70a is sealed.

  A caulking portion 74 for fixing the second housing 70 to the first housing 20 is formed at the end of the first tube portion 71 opposite to the third tube portion 73. The caulking portion 74 is bent from the side surface 21a of the enlarged diameter portion 21 in the first housing 20 to the back surface 21b side opposite to the fixed surface 20a, and the second housing 70 is formed by the caulking portion 74 and the opposing surface 70a. The enlarged diameter portion 21 is sandwiched.

  Next, in the pressure sensor 10 configured as described above, a configuration of the protective member 60 that is a characteristic part will be described.

  The protection member 60 covers and protects the sensor chip 30, the end 41 exposed in the recess 24 of the terminal 40, and the bonding wire 50, and transmits the pressure of the measurement fluid to the diaphragm 31 of the sensor chip 30. To fulfill. The protective member 60 is formed using an elastic member 61 formed by curing liquid rubber and a material having a higher Young's modulus than the elastic member 61, and at least a part of the protective member 60 is embedded in the elastic member 61. And a held high hardness member 62.

  In this embodiment, the elastic member 61 is made of room temperature curing type silicone rubber, and the high hardness member 62 is made of ceramic (alumina) in order to reduce the difference in linear expansion coefficient from the sensor chip 30. In addition, as the elastic member 61, other than that, fluorine-based rubber or the like can be adopted. Moreover, it is not limited to a room temperature curing type, Other heat curing types etc. can also be employ | adopted. Moreover, as the high hardness member 62, metals, such as SUS, can also be employ | adopted besides ceramics.

  As described above, the elastic member 61 is formed by curing liquid rubber, and in this embodiment, the elastic member 61 is filled to a position flush with the fixed surface 20a so as to fill the concave portion 24 of the first housing 20. Has been. For this reason, the surface 61a opposite to the surface in contact with the bottom surface 24a of the recess 24 in the elastic member 61 is substantially flush with the fixed surface 20a.

  On the other hand, the high hardness member 62 has a cylindrical shape, and is located only above the diaphragm 31 in the one surface 30 a of the sensor chip 30. That is, the high hardness member 62 is arranged at a position that does not overlap the bonding wire 50 in the direction along the one surface 30 a of the sensor chip 30. As shown in FIG. 3, the center of the high hardness member 62 and the center of the diaphragm 31 coincide with each other at a point C <b> 1 in the direction along the one surface 30 a of the sensor chip 30. In addition, one end of the columnar high hardness member 62 is one surface 30 a of the sensor chip 30 and is in contact with the diaphragm 31, and the other end is flush with the surface 61 a of the elastic member 61. That is, the high hardness member 62 is exposed to the outside from the elastic member 61 while being in contact with the diaphragm 31 of the sensor chip 30.

  As described above, in the present embodiment, the columnar high hardness member 62 is located only above the diaphragm 31 in the one surface 30 a of the sensor chip 30, and the high hardness member 62 in the recess 24 of the first housing 20. The elastic member 61 is arrange | positioned at all the parts except the arrangement | positioning part. Therefore, the elastic member 61 covers the portion of the sensor chip 30 excluding the contact portion of the high hardness member 62, the end portion 41 exposed in the recess 24 in the terminal 40, and the bonding wire 50.

  The protection member 60 according to the present embodiment can be formed before the second housing 70 is assembled to the first housing 20, or can be formed after the second housing 70 is assembled to the first housing 20. .

  For example, the first housing 20 in which the terminal 40 is insert-molded is prepared, and the pedestal 34 is bonded and fixed to the bottom surface 24a of the recess 24 in a state where the fixing surface 20a faces upward. The sensor chip 30 is anodically bonded. Next, the pads 33 of the sensor chip 30 and the end portions 41 of the terminals 40 are connected by bonding wires 50. Then, the high hardness member 62 is adsorbed, and the high hardness member 62 is held at a predetermined position so that the end portion comes into contact with the diaphragm 31 of the sensor chip 30, and in this state, the recess 24 is filled with liquid rubber. And elastic member 61 and by extension, protection member 60 can be formed by hardening rubber at normal temperature. After the protective member 60 is formed, the O-ring 80 is disposed in the groove 25 of the first housing 20, and the second housing 70 may be assembled to the first housing 20 in this state.

  Further, the second housing 70 is assembled to the first housing 20 without forming the protective member 60. Then, the high hardness member 62 is adsorbed to the concave portion 24 of the first housing 20 through the pressure introduction hole 72 a of the second housing 70, and the high hardness member 62 is in contact with the diaphragm 31 of the sensor chip 30. 62 is held in place. In this state, liquid rubber is filled into the recess 24 through the pressure introducing hole 72a. And elastic member 61 and by extension, protection member 60 can be formed by hardening rubber at normal temperature.

  Next, the effect of the characteristic part of the pressure sensor 10 according to the present embodiment will be described.

  In the present embodiment, the protection member 60 having the elastic member 61 and the high hardness member 62 can protect the sensor chip 30, the end portion 41 of the terminal 40, and the bonding wire 50 from the liquid. Further, as the protective member 60, oil (liquid) is not used as in the prior art, and a metal diaphragm is unnecessary for oil sealing. Therefore, the size of the metal diaphragm does not need to be increased in order to prevent the oil from expanding in volume due to a change in ambient temperature and the stress from acting on the diaphragm 31 of the sensor chip 30. For this reason, a physique can also be reduced in size.

  In addition, at least a part of the sensor chip 30, the end 41 exposed in the recess 24 in the terminal 40, and the bonding wire 50 are covered with an elastic member 61 formed by curing liquid rubber. For this reason, even if the pressure of the measurement fluid suddenly increases due to the pulsation of the pump that sends out the measurement fluid, the energy received from the measurement fluid by the elastic member 61 can be attenuated. Therefore, particularly the bonding wire 50 can be protected against sudden pressure fluctuations.

  The protection member 60 has a high hardness member 62 disposed above the diaphragm 31. The high hardness member 62 is harder than the elastic member 61, and the amount of attenuation of energy received from the measurement fluid is small. For this reason, pressure can be efficiently transmitted to the diaphragm 31 as compared with the configuration in which only the elastic member 61 is disposed also on the diaphragm 31.

  As described above, according to the present embodiment, in the pressure sensor 10 that measures the pressure of the measurement fluid including the liquid, the bonding wire 50 can be protected against sudden pressure fluctuations while reducing the size of the body.

  In the present embodiment, the high hardness member 62 is exposed to the outside from the surface 61 a of the elastic member 61. For this reason, the measurement fluid acts directly on the high hardness member 62. Therefore, the pressure can be efficiently transmitted to the diaphragm 31 as compared with the configuration in which the high hardness member 62 is covered with the elastic member 61 and is not exposed to the outside.

  In the present embodiment, the high hardness member 62 is in contact with the diaphragm 31 of the sensor chip 30. For this reason, the pressure is directly transmitted to the sensor chip 30 via the high hardness member 62. According to this, the elastic member 61 exists between the diaphragm 31 and the high-hardness member 62, and the pressure can be efficiently transmitted to the diaphragm 31 as compared with a configuration in which the elastic member 61 attenuates the energy. .

  In the present embodiment, the high hardness member 62 is disposed at a position that does not overlap the bonding wire 50 in the direction along the one surface 30 a of the sensor chip 30. Thus, since the high hardness member 62 does not exist above the bonding wire 50, the thickness of the elastic member 61 can be increased accordingly. Thereby, even if the pressure of the measurement fluid suddenly increases, the energy received from the measurement fluid can be effectively attenuated by the elastic member 61.

  In the present embodiment, the center of the high hardness member 62 and the center of the diaphragm 31 coincide with each other at the point C1 in the direction along the one surface 30a of the sensor chip 30. For this reason, the displacement amount of the diaphragm 31 can be increased as compared with the configuration in which the center of the high hardness member 62 and the center of the diaphragm 31 are displaced. That is, the sensor sensitivity can be further increased.

  In the present embodiment, an example is shown in which one end of the high hardness member 62 is one surface 30a of the sensor chip 30 and is in contact with the portion of the diaphragm 31, and the other end is flush with the surface 61a of the elastic member 61. . However, the arrangement of the high hardness member 62 is not limited to the above example. What is necessary is just to be arrange | positioned above the diaphragm 31 at least.

  For example, in the example illustrated in FIG. 4, the high hardness member 62 does not contact the diaphragm 31, and the elastic member 61 is interposed between the diaphragm 31 and the diaphragm 31. Further, the high hardness member 62 is completely embedded in the elastic member 61, and the elastic member 61 is located on the high hardness member 62. Even with such a configuration, it is possible to efficiently transmit the pressure to the diaphragm 31 as compared with a configuration in which only the elastic member 61 exists above the diaphragm 31.

  In the example shown in FIG. 5, the high hardness member 62 protrudes from the surface 61 a of the elastic member 61 to the outside. With this arrangement, when forming the protective member 60, the concave portion 24 can be filled with liquid rubber and cured while the portion of the high hardness member 62 protruding from the elastic member 61 is gripped. Therefore, the high hardness member 62 can be easily arranged with respect to the elastic member 61. In FIG. 5, the high hardness member 62 is in contact with the diaphragm 31 of the sensor chip 30, but may be configured not to contact.

  In the present embodiment, a cylindrical example is shown as the high hardness member 62, but a prismatic shape (rectangular, triangular, etc.) may be used.

(Second Embodiment)
In the present embodiment, description of portions common to the pressure sensor 10 shown in the above embodiment is omitted. In the first embodiment, an example in which the elastic member 61 is disposed only in the recess 24 of the first housing 20 has been described. On the other hand, in this embodiment, as shown in FIG. 6, the elastic member 61 is farther from the recess bottom surface 24 a than the facing surface 70 a of the second housing 70 in the direction perpendicular to the one surface 30 a of the sensor chip 30. To the position. Specifically, a portion from the bottom surface 24 a of the recess 24 of the first housing 20 to a part of the third cylindrical portion 73 in the second housing 70 is filled. In the example shown in FIG. 6, one end of the high hardness member 62 is in contact with the portion of the diaphragm 31 on the one surface 30 a of the sensor chip 30, and the other end is flush with the surface 61 a of the elastic member 61.

  With such a configuration, the clearance between the fixed surface 20a of the first housing 20 and the opposing surface 70a of the second housing 70, that is, the O-ring 80 can be protected by the protection member 60 (elastic member 61). . Therefore, an inexpensive O-ring 80 can be used.

  In the pressure sensor 10 having such a configuration, as shown in the first embodiment, after the second housing 70 is assembled to the first housing 20, the pressure introduction hole 72a of the second housing 70 is provided. It can be obtained by forming the protective member 60.

(Third embodiment)
In the present embodiment, description of portions common to the pressure sensor 10 shown in the above embodiment is omitted. In the said embodiment, the example whose shape of the high hardness member 62 was a column shape was shown. In other words, an example is shown in which the area of the high hardness member 62 in the direction along the one surface 30a of the sensor chip 30 is constant in the direction perpendicular to the one surface 30a.

  On the other hand, in this embodiment, as shown in FIGS. 7 and 8, the area of the high hardness member 62 in the direction along the one surface 30 a of the sensor chip 30 is the end of the sensor chip 30 on the side in contact with the diaphragm 31. The end 62b opposite to the end 62a is larger than 62a. More specifically, it has a conical shape in which the area increases as the distance from the sensor chip 30 increases. Further, as shown in FIG. 8, all of the end portion 62a on the sensor chip 30 side (the portion surrounded by the one-dot chain line in FIG. 8) is in contact with the diaphragm 31, and the opposite end portion 62b is the diaphragm 31. The pad 33 and thus the bonding wire 50 are provided so as not to overlap.

  Here, assuming that the area of the end 62b opposite to the sensor chip 30 is S1, the pressure of the measurement fluid acting on the end 62b is P1, the area of the end 62a on the sensor chip 30 side is S2, and the pressure is P2. Ideally, P1 · S1 = P2 · S2. Therefore, if it is set as the structure shown to this embodiment, the pressure which the diaphragm 31 receives by the high hardness member 62 can be raised. That is, sensor sensitivity can be increased.

  In particular, in the present embodiment, the conical high hardness member 62 is adopted, and the side surface connecting the end portions 62a and 62b is tapered, so that the elastic member 61 is compared with the stepped high hardness member 62 and the like. It is possible to reduce the viscous resistance acting between the high hardness member 62 and the high hardness member 62, thereby further increasing the sensitivity of the sensor.

  In the present embodiment, the high hardness member 62 is provided so as not to overlap the bonding wire 50 in the direction along the one surface 30 a of the sensor chip 30. For this reason, the bonding wire 50 can be effectively protected as compared with the configuration in which the high hardness member 62 is also located above the bonding wire 50.

  Further, the length of the leak path generated from the surface 61 a of the elastic member 61 to the sensor chip 30 can be increased along the interface between the high hardness member 62 and the elastic member 61.

  The shape of the high-hardness member 62, which is larger at the end 62b opposite to the end 62a than at the end 62a on the side of the sensor chip 30 that contacts the diaphragm 31, is limited to the conical shape described above. is not. For example, a pyramid shape may be used. In addition, a stepped shape in which the area changes for each predetermined length in a direction perpendicular to the one surface 30a of the sensor chip 30 may be used.

  Further, the high hardness member 62 may be arranged so that a part of the high hardness member 62 is positioned above the bonding wire 50. According to this, the area S1 of the end 62b of the high hardness member 62 can be further increased, and the sensor sensitivity can be further increased.

(Fourth embodiment)
In the present embodiment, description of portions common to the pressure sensor 10 shown in the above embodiment is omitted. In the said embodiment, the example of the protection member 60 which has the elastic member 61 and the high hardness member 62 was shown. In contrast, the present embodiment is characterized in that the protection member 60 includes a cover 63 together with the elastic member 61 and the high hardness member 62 as shown in FIGS.

  In the recess 24 of the first housing 20, a support surface 26 a that is farther from the bottom surface 24 a of the recess 24 than the bonding wire 50 in the direction perpendicular to the one surface 30 a of the sensor chip 30 and supports the cover 63, A support portion 26 is provided between the surface 61 a of the elastic member 61 and the bonding wire 50.

  The cover 63 is formed using a material (resin, ceramic, metal, etc.) having a higher Young's modulus than the elastic member 61. And it is fixed to the support part 26, and it arrange | positions so that the high hardness member 62, the sensor chip 30, the edge part 41 of the terminal 40, and the bonding wire 50 may not be contacted, and the bonding wire 50 may be covered. In the present embodiment, the cover 63 is configured using the same material (for example, PPS) as the constituent material of the first housing 20.

  In the example shown in the present embodiment, as shown in FIG. 9B, the cover 63 has a planar circular shape corresponding to the concave portion 24, and a through hole 63 a corresponding to the high-hardness member 62 at the center portion thereof. have. Further, in a state where the cover 63 is bonded and fixed to the support portion 26, a region below the cover 63 in the recess 24 is filled with liquid rubber so as to form the elastic member 61 so as to surround the through hole 63 a. Four through holes 63b are formed. As shown in FIG. 9A, the through holes 63 b are formed above the end portions 41 corresponding to the end portions 41 of the four terminals 40.

  As described above, when the cover 63 is provided above the bonding wire 50 and this cover 63 is fixed to the support portion 26 of the first housing 20, the protective member 60 is protected from the measurement fluid when the pressure of the measurement fluid suddenly increases. Part of the received energy can be released to the first housing 20 via the cover 63 and the support portion 26. Thereby, the bonding wire 50 can be protected more effectively.

  In this embodiment, as shown in FIGS. 10 and 11, the cover 63 is completely covered with the elastic member 61. Further, the elastic member 61 is disposed up to the third cylindrical portion 73 of the second housing 70. However, as shown in FIG. 12, a part of the cover 63 may be exposed from the elastic member 61. In FIG. 12, the surface opposite to the bottom surface 24a of the cover 63 is exposed. Further, the elastic member 61 may be arranged only in the recess 24 of the first housing 20.

  Moreover, the form of the support part 26 is not limited to the said example. Any configuration that protrudes from the wall surface (for example, the bottom surface 24 a) of the recess 24 of the first housing 20 into the recess 24 and can support the cover 63 above the bonding wire 50 can be adopted.

  Further, the cover 63 is not limited to the above example. For example, the cover 63 may be divided and arranged for every four bonding wires 50. That is, a plurality of covers 63 may be used. A substantially cross-shaped cover 63 can also be employed.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the present embodiment, an example in which the pressure sensor 10 includes the second housing 70 together with the first housing 20 has been described. However, as shown in FIG. 13, the pressure sensor 10 includes at least a first housing 20 having a recess 24, a pressure measuring sensor chip 30 disposed in the recess 24 of the first housing 20, and a first housing. 20, a terminal 40 as an external connection terminal held by 20, a bonding wire 50 that electrically connects the sensor chip 30 and the terminal 40, a part of the sensor chip 30, the terminal 40, and the bonding wire 50 are covered. What is necessary is just to provide the protection member 60. FIG. In FIG. 13, the first housing 20 is made of a metal material, and the terminal 40 is hermetically sealed to the first housing 20.

DESCRIPTION OF SYMBOLS 10 ... Pressure sensor 20 ... 1st housing 24 ... Recessed part 24a ... Bottom face (recessed part bottom face)
30 ... Sensor chip 31 ... Diaphragm 33 ... Pad 40 ... Terminal (terminal)
50 ... Bonding wire 60 ... Protective member 61 ... Elastic member 62 ... High hardness member 70 ... Second housing 72a ... Pressure introducing hole

Claims (12)

A first housing (20) having a recess (24);
A diaphragm (31) formed on one surface (30a) and having a gauge resistance, and an external connection pad (33) formed on the one surface (30a) in a peripheral region (32) surrounding the diaphragm (31) The back surface (30b) opposite to the one surface (30a) is disposed on the recess bottom surface (24a) so as to face the recess bottom surface (24a) of the first housing (20). A sensor chip (30);
The first housing (20) is held, one end (41) is exposed in the recess (24), and the other end (42) is different from the recess (24). A terminal (40) for external connection exposed to the outside of the housing (20);
A bonding wire (50) for electrically connecting the end (41) exposed in the recess (24) of the terminal (40) and the pad (33) of the sensor chip (30);
A protective member (60) covering the sensor chip (30), an end (41) exposed in the recess (24) of the terminal (40), and the bonding wire (50);
A pressure sensor in which a pressure of a measurement fluid including a liquid is transmitted to the sensor chip (30) via the protective member (60),
The protective member (60) is formed using an elastic member (61) obtained by curing liquid rubber, and a material having a Young's modulus higher than that of the elastic member (61). A high-hardness member (62) partially embedded and held by the elastic member (61),
The elastic member (61) covers at least a part of the sensor chip (30), the end (41) exposed in the recess (24) of the terminal (40), and the bonding wire (50). ,
The pressure sensor according to claim 1, wherein the high hardness member (62) is disposed above the diaphragm (31).   The pressure according to claim 1, wherein the high hardness member (62) is exposed to the outside from a surface (61a) opposite to a surface of the elastic member (61) in contact with the bottom surface (24a) of the recess. Sensor.   The pressure sensor according to claim 2, wherein the high hardness member (62) protrudes from the surface (61a) of the elastic member (61) to the outside.   The pressure sensor according to any one of claims 1 to 3, wherein the high hardness member (62) is in contact with a diaphragm (31) of the sensor chip (30).   The area of the high hardness member (62) in the direction along the one surface (30a) of the sensor chip (30) is more than the end portion (62a) contacting the diaphragm (31) of the sensor chip (30). The pressure sensor according to claim 4, wherein the end (62b) opposite to the part (62a) is larger.   The pressure sensor according to claim 5, wherein the high hardness member (62) is formed in a spindle shape.   The said high hardness member (62) is arrange | positioned in the position along the one surface (30a) of the said sensor chip (30) in the position which does not overlap with the said bonding wire (50). The pressure sensor according to any one of claims.   The center of the high hardness member (62) and the center of the diaphragm (31) coincide with each other in a direction along one surface (30a) of the sensor chip (30). The pressure sensor according to claim 1. The first housing (20) is farther from the recess bottom surface (24a) than the bonding wire (50) in a direction perpendicular to the one surface (30a) of the sensor chip (30), and is elastic. A support (26) located between the bonding wire (50) and the surface (61a) opposite to the surface in contact with the bottom surface (24a) of the recess in the member (61);
The protective member (60) is formed using a material having a higher Young's modulus than the elastic member (61), does not contact the high-hardness member (62), and covers the bonding wire (50). The pressure sensor according to any one of claims 1 to 8, further comprising a cover (63) fixed to the support portion (26).   The pressure sensor according to any one of claims 1 to 9, wherein the high-hardness member (62) is formed using a ceramic material or a metal material. An accommodation space that is formed in a cylindrical shape and accommodates a recess (24) of the first housing (20) as a space inside the cylinder, and a recess (24) of the first housing (20) disposed in the accommodation space. A second housing (70) having an introduction space for introducing a measurement fluid with respect to
The first housing (20) has an annular fixed surface (20a) surrounding the concave portion (24) and a groove (25) formed along the annular shape on the fixed surface (20a).
The second housing (70) has an opposing surface (70a) facing the fixed surface (20a) as an inner wall surface thereof,
An annular seal member (80) disposed in the groove (25) is in close contact with the fixed surface (20a) of the first housing (20) and the opposing surface (70a) of the second housing (70). The pressure sensor according to any one of claims 1 to 10, wherein:   In the direction perpendicular to one surface (30a) of the sensor chip (30), the elastic member (61) is farther from the concave bottom surface (24a) than the facing surface (70a) of the second housing (70). The pressure sensor according to claim 11, wherein the pressure sensor is disposed up to a position.

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