JP4893529B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor formed by covering and protecting a pressure receiving surface of a sensor chip with a protective member containing oil.

  Conventionally, a pressure sensor that detects a pressure and generates an electric signal at a level corresponding to the detected value by covering it with a protective member having chemical resistance is disclosed in Patent Document 1, for example. Proposed. Specifically, in Patent Document 1, a detection unit that includes a resin package, a sensor chip that is mounted in a recess of the resin package and performs pressure detection, and a glass pedestal that holds the sensor chip, and the detection unit are covered. There has been proposed a pressure sensor configured to include a protective member that protects.

  The protective member has a two-layer structure of an upper layer and a lower layer. For example, fluororubber is employed as the lower layer protective member, and a fluorine gel having a lower elastic modulus than the lower layer protective member is employed as the upper layer protective member. . Each of these protective members is mixed with a fluorinated oil having a glass transition temperature lower than that of the base material, and the glass transition temperature of each protective member is made lower than the glass transition temperature of the base material. As a result, the protective member is prevented from becoming hard at a low temperature, and the deterioration of the characteristics of the sensor chip is reduced.

The same amount of non-functional fluorinated oil is mixed with each of the upper and lower protective members. This prevents the movement of the fluorinated oil at the interface between the layers of the protective member.
JP 2001-304999 A

  However, the conventional technique has a problem that non-functional fluorine-based oil does not bind to fluorine-based rubber or fluorine gel, and thus escapes from the upper protective member due to bleeding or volatilization. As a result, the fluorinated oil located on the lower protective member side moves to the location where the fluorinated oil has escaped in the upper protective member, and the fluorinated oil also protects the upper layer. It escapes from the member.

  When such movement of the fluorinated oil occurs in the upper protective member, the fluorinated oil moves from the lower protective member to the upper protective member. Therefore, the amount of fluorine-based oil mixed in each of the upper and lower protective members is reduced from the amount initially mixed. As a result, each protection member shrinks and hardens due to changes over time of each protection member, which may affect the characteristics of the sensor chip.

  In view of the above points, the present invention provides a pressure sensor that can prevent oil from being removed from a protective member that contacts the sensor chip, avoids hardening of the protective member, and does not affect the characteristics of the sensor chip. The purpose is to do.

  In order to achieve the above object, the present invention provides an amount of oil material contained in at least the first protection member (51) in contact with the pressure receiving surface of the sensor chip (20, 70) among the plurality of protection members (50). The amount of the oil material contained in the second protective member (52) in contact with the first protective member (51) is larger than that of the first protective member (51). It is a source of supply.

  According to this, oil can always be supplied to the 1st protection member (51) which touches a sensor chip (20, 70) from the 2nd protection member (52) which is an oil supply source. Accordingly, the oil can be always supplied to the first protection member (51), so that the oil can be prevented from coming off from the first protection member (51), and is in contact with the sensor chip (20, 70). It can be avoided that the first protective member (51) shrinks and hardens over time. Thereby, it is possible not to affect the characteristics of the sensor chip (20, 70), and it is possible to provide a pressure sensor in which the characteristics of the sensor chip (20, 70) are stable.

  In this case, the pressure sensor has a plate shape having one surface and the other surface, and a recess (12) is formed on one surface, and the pressure introducing hole (13) penetrating the bottom surface and the other surface of the recess (12). ) Is formed, and the sensor chip (20) is a plate having one surface and the other surface, and the one surface and the other surface are pressure receiving surfaces, and each pressure receiving surface. A differential pressure between the pressures applied to each of the two is detected, and one of the pressure receiving surfaces is disposed in the recess (12) so as to face the pressure introducing hole (13) of the case (10). It can be configured.

  Thus, in the sensor chip (20) for detecting the differential pressure, the first protective member (51) in contact with one of the pressure receiving surfaces can be prevented from becoming hard over time.

  Further, the plurality of protection members (50) are configured by only two layers of the first protection member (51) and the second protection member (52), and the first protection member (51) is the pressure of the sensor chip (20). The pressure introduction hole (13) is filled so as to be in contact with one of the pressure receiving surfaces, and the second protection member (52) is disposed in the pressure introduction hole (13) and on the first protection member (51). be able to.

  Furthermore, the second protection member (52) can be configured as a plate member (53) that is in the form of a sheet containing an oil material and is disposed on the first protection member (51).

  According to this, when the plate member (53) slides on the first protective member (51), the pressure is guided to the pressure receiving surface of the sensor chip (20) via the first protective member (51). it can. Further, the plate member (53) functions as an oil supply source of the first protection member (51), so that oil loss of the first protection member (51) can be prevented.

  Further, when the pressure sensor is manufactured, the plate member (53) is simply placed on the first protective member (51) after the first protective member (51) is filled in the pressure introducing hole (13). The plate member (53) can be easily installed.

  An oil supply chamber (16) in which liquid oil (17) is disposed is provided in the case (10), and the oil (17) is provided in a passage (19) leading from the oil supply chamber (16) to the pressure introduction hole (13). ) And the oil (17) is in direct contact with the first protective member (51) disposed in the pressure introducing hole (13), and the oil (17) is supplied to the first protective member (51) as an oil supply source. It can be.

  Thereby, it is possible to prevent the amount of oil material contained in the first protection member (51) from decreasing, and it is possible to prevent the first protection member (51) from being cured.

  In the above description, the pressure sensor including the sensor chip (20) for detecting the differential pressure has been described. However, in the pressure sensor formed by covering and protecting the sensor chip (70) for detecting the absolute pressure with a plurality of protective members, By prescribing the amount of oil material contained in the protective member in the same manner as described above, the protective member in contact with the sensor chip (70) can be prevented from being cured, and the characteristics of the sensor chip (70) can be maintained well. Can do.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings. In addition, the third embodiment and the seventh embodiment among the following embodiments from the first embodiment to the other embodiments are used as reference examples.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The pressure sensor shown in the present embodiment is used as, for example, an intake pressure sensor installed in an intake manifold or the like, or a pressure sensor that detects the pressure of exhaust gas in an exhaust gas purification system (DPF system) of an automobile diesel engine. Is.

  FIG. 1 is a schematic cross-sectional view of a pressure sensor according to a first embodiment of the present invention. As shown in this figure, the pressure sensor includes a case 10, a sensor chip 20, a circuit chip 30, a chip surface side protection member 40, and a chip back surface side protection member 50.

  The case 10 is, for example, a plate formed by molding a resin material such as PPS (polyphenylene sulfide), PBT (polybutylene terephthalate) or epoxy resin using a mold, and a plurality of conductor portions 11 are inserted. It is molded. The conductor part 11 is a terminal for electrical connection between the pressure sensor and the outside, and is made of a conductive material such as copper, for example. A recess 12 is formed on one surface of the plate forming the case 10, and a sensor chip 20 for pressure detection is stored in the recess 12.

  The sensor chip 20 detects a pressure and generates an electric signal having a level corresponding to the pressure, and has a plate shape utilizing a piezoresistance effect. Specifically, the sensor chip 20 has a diaphragm 21 that is a thin portion and a strained portion on one surface of the plate, and a recess 22 formed by anisotropic etching or the like to form the diaphragm 21 on the other surface of the plate. It is a semiconductor diaphragm type having That is, the sensor chip 20 has a recess 22 on the other surface of the plate, and has a diaphragm 21 as a distortion portion on one surface of the plate corresponding to the recess 22.

  Hereinafter, the surface of the sensor chip 20 on which the diaphragm 21 is formed is referred to as the front surface of the sensor chip 20, and the surface on which the recess 22 is formed is referred to as the back surface of the sensor chip 20. In this embodiment, since pressure is received by the front surface and the back surface of the sensor chip 20, both surfaces of the sensor chip 20 become pressure receiving surfaces.

  The diaphragm 21 is provided with a sensing unit including, for example, a bridge circuit configured by a diffused resistor or the like. Thereby, when pressure is applied to both surfaces of the plate of the sensor chip 20, the diaphragm 21 is distorted by the differential pressure between the two pressures, and an electrical signal corresponding to the differential pressure is generated in the bridge circuit.

  A pedestal 23 made of glass or the like is bonded to the back surface of the sensor chip 20 by anodic bonding or the like and integrated with the sensor chip 20. The pedestal 23 is adhered to the bottom surface of the recess 12 of the case 10 via an adhesive 24 and is housed and fixed in the case 10. Thus, the sensor chip 20 is fixed to the case 10 with the back surface of the sensor chip 20 facing the case 10.

  As the adhesive 24, a soft adhesive, for example, a silicon adhesive or a fluorosilicone adhesive, in which the thermal stress of the adhesive 24 hardly affects the sensor characteristics is employed.

  Further, one end of the conductor portion 11 insert-molded in the case 10 is exposed in the recess 12 of the case 10. The sensor chip 20 is connected to the exposed portion of the conductor portion 11 through the bonding wire 61 in the recess 12 and is electrically connected to the outside.

  The circuit chip 30 has a function of outputting a drive signal to the sensor chip 20, outputting a detection signal to the outside, inputting an electric signal from the sensor chip 20, calculating and amplifying the signal, and outputting the signal to the outside. A circuit is provided. As such a circuit chip 30, for example, a CMOS transistor or a bipolar transistor is formed on a silicon substrate or the like by a semiconductor process.

  Such a circuit chip 30 is housed and fixed in the recess 12 of the case 10. The circuit chip 30 and the sensor chip 20 are connected and electrically connected via bonding wires 62 made of gold, aluminum, or the like.

  Further, a conductor portion (not shown) is insert-molded in the vicinity of the circuit chip 30 in the case 10, and the conductor portion and the circuit chip 30 are connected via a bonding wire or the like and electrically connected to the outside. .

  In addition, the pedestal 23 is formed with a through hole 23a that penetrates from the surface to which the sensor chip 20 is fixed to the opposite surface. On the other hand, a pressure introduction hole 13 that penetrates from one surface of the plate forming the case 10 to the other surface is provided at a position corresponding to the through hole 23 a of the pedestal 23 on the bottom surface of the recess 12 of the case 10.

  The pressure introducing hole 13 is a through hole that guides pressure to the back surface of the sensor chip 20, and is closed by the sensor chip 20 via the pedestal 23. Thus, the recess 12 formed on one surface of the case 10 and the pressure introducing hole 13 opened on the other surface of the case 10 are partitioned by the sensor chip 20. Thereby, the diaphragm 21 of the sensor chip 20 is configured to receive pressure from the one surface side of the case 10 and the other surface side of the case 10.

  The pressure introducing hole 13 includes a first hole 13a that opens to the other surface of the case 10 and a second hole 13b that has a smaller diameter than the first hole 13a and opens to the bottom surface of the recess 12 of the case 10. ing. In the present embodiment, the connecting portion between the first hole 13a and the second hole 13b has a stepped shape due to the difference in diameter between the first hole 13a and the second hole 13b. Thus, the pressure receiving area can be widened because the diameter of the first hole 13a is larger than that of the second hole 13b on the sensor chip 20 side.

  The chip front surface side protection member 40 and the chip back surface side protection member 50 seal and protect each of the above-described components. As described above, since the pressure sensor is placed in a severe environment exposed to a highly corrosive pressure medium such as exhaust gas, it is necessary to protect each component of the pressure sensor from the highly corrosive pressure medium. is there.

  Specifically, the chip surface side protection member 40 is filled in the recess 12 of the case 10. The chip surface side protective member 40 seals and protects the interface between the conductor portion 11 and the case 10, the sensor chip 20, the circuit chip 30, and the bonding wires 61 and 62.

  On the other hand, on the back side of the sensor chip 20, the pressure back hole 13 and the through hole 23 a of the pedestal 23 are filled with the chip back side protection member 50. The chip back surface side protection member 50 seals the back surface of the sensor chip 20 and prevents foreign matter from entering the pressure introducing hole 13. Further, it is possible to prevent problems such as characteristic fluctuations due to dirt adhering to the back surface of the sensor chip 20, blockage of the pressure introduction hole 13 due to freezing of condensed water, and destruction of the sensor chip 20 due to volume expansion when water freezes. It has become.

  As these chip surface side protection member 40 and chip back surface side protection member 50, for example, fluorine gel, silicon gel, fluorosilicon gel, or the like is employed. In particular, when the exhaust gas pressure is measured with a pressure sensor, the condensed water from the exhaust gas has a strong acidity because the nitrogen oxides and sulfur oxides of the exhaust gas dissolve therein. As the back surface side protection member 50, it is desirable to employ a fluorine gel with strong acid resistance.

  The chip back surface side protection member 50 includes a first protection member 51 that fills the through hole 23 a of the base 23 and the pressure introduction hole 13 so as to contact the back surface of the sensor chip 20, and a first hole 13 a of the pressure introduction hole 13. It is comprised as a two-layer structure with the 2nd protection member 52 provided in the inside and covering the 1st protection member 51 and contacting a pressure medium.

  In the first protective member 51 and the second protective member 52, when the thickness along the axial direction of the pressure introducing hole 13 is seen, the second protective member 52 is provided in a layer form thinner than the first protective member 51. . As each of these protection members 51 and 52, the above-mentioned fluorine gel or the like is employed.

  The first protective member 51 and the second protective member 52 are mixed with oil materials in order to prevent the protective members 51 and 52 from becoming hard over time. This oil material can adjust the hardness of each protection member 51 and 52 according to the amount of mixing with each protection member 51 and 52, for example, fluorine oil is adopted. Some fluorine-based oils are non-functional. For example, non-functional perfluoroalkyl can be used as the non-functional fluorine-based oil.

  Further, the amount of oil contained in the second protective member 52 in contact with the pressure medium is larger than the amount of oil contained in the first protective member 51 in contact with the back surface of the sensor chip 20. For example, the amount of oil contained in the first protective member 51 is 40% by weight, and the amount of oil contained in the second protective member 52 is 60% by weight.

  Thus, the grounds for increasing the amount of oil contained in the second protective member 52 rather than the first protective member 51 will be described.

  The inventors (1) Since the stress is released in the direction in which the oil swells, the oil does not affect the sensor chip 20. (2) In each of the protective members 51 and 52, the oil reduction speed is exposed to the atmosphere. The saturation value is determined by the total volume of each protection member 51, 52. (3) The oil transfer speed is determined by the contact area of each protection member 51, 52. However, on the premise that the saturation value is determined by the total volume of the protective members 51 and 52, the characteristics of the protective members 51 and 52 relating to oil were examined.

  In the present invention, all structures have at least one open end. Specifically, in FIG. 1, the surface side of the protective member 50 facing the sensor chip 20 (on the side opposite to the sensor chip 20) is open. In addition, similarly in the configuration of FIG. 8 to be described later on which the plate member 53 having the sliding portion is mounted, the surface facing the sensor chip 70 can be regarded as a kind of open end.

  And this configuration having at least one open end can release stress on the open end side, that is, the surface side opposite to the sensor chip 20 (opposite side of the sensor chip 20). An unfavorable stress is not generated in the diaphragm 21. Therefore, the sensor chip 20 is not affected by the oil.

  First, the inventors set the investigation target as a gel material, and applied a temperature of 120 ° C. or higher, for example, 150 ° C., which is a general temperature received by a pressure sensor mounted on a vehicle, to the gel material of oil concentration X. The weight of the gel material was examined. The result is shown in FIG.

  As shown in FIG. 2, when the oil concentration of the oil contained in the gel material is X, the weight of the gel material decreases with time and decreases by 2.0% to be saturated. In addition, in the case of 2X in which the oil concentration of the oil contained in the gel material is doubled, the weight of the gel material is twice as much as that in the case where the oil concentration is X, that is, 4.0%, and is saturated. That is, the weight of the gel material decreased due to the oil escaping from the gel material. In this case, it can be said that the weight of the gel material tends to decrease with time as the oil concentration is increased. In this way, the weight of the gel material containing oil is reduced by the loss of oil over time.

  When this result is applied to the present embodiment, in the configuration of the chip back surface side protection member 50 shown in FIG. 1, the weight of the second protection member 52 is finally reduced by 2.0% over time. Therefore, the amount of oil in consideration of the weight loss by heating of the second protective member 52 is set to be larger than the amount of oil contained in the first protective member 51 that is supplemented with oil.

  For this reason, an oil concentration gradient is provided in each of the protection members 51 and 52 by setting the oil mixing amount of the second protection member 52 functioning as an oil supply source to, for example, 1.02 times or more of the oil mixing amount of the first protection member 51. It can be said that the oil mixing amount of the first protective member 51 can be prevented from decreasing. Further, when the oil concentration of the first protection member 51 is 2X, the oil mixing amount of the second protection member 52 may be, for example, 1.04 times or more with respect to the oil mixing amount of the first protection member 51. The oil concentration gradient such as 1.02 is an example, and the oil concentration gradient is determined by the material and volume of the protection members 51 and 52.

  Then, the inventors examined the amount of movement of the oil mixture amount of each of the protective members 51 and 52. FIG. 3 shows the correlation between the increased weight of the protective member supplemented with oil and time. In FIG. 3, 2X: 0 is an increase in weight of the first protective member 51 having an oil concentration of 0 when the second protective member 52 having an oil concentration of 2X and the first protective member 51 having an oil concentration of 0 are brought into contact with each other. Is shown. Similarly, 2X: X means that when the second protective member 52 having an oil concentration of 2X is brought into contact with the first protective member 51 having an oil concentration of X, 2X: 2X means that the second protective member having an oil concentration of 2X. The case where 52 and the 1st protection member 51 whose oil concentration is 2X is made to contact is shown.

  As shown in FIG. 3, even if the protective members 51 and 52 having an oil concentration of 2X (2X: 2X) are brought into contact with each other, the weight of the first protective member 51 hardly changes. However, the amount of oil in the second protective member 52 on the side of replenishing oil is made larger than that of the first protective member 51 on the side of replenishing oil (2X: X, 2X: 0), that is, each protective member. It can be seen that by increasing the difference in the amount of oil contained in each of 51 and 52, the weight of the first protective member 51 on the oil replenishment side increases.

  That is, when the difference in the amount of oil contained in each of the protection members 51 and 52 is large, the amount of oil that moves from the second protection member 52 that is an oil supply source to the first protection member 51 that contacts the back surface of the sensor chip 20 also increases. . Thereby, the oil amount of the 1st protection member 51 can be increased with progress of time, and the 1st protection member 51 can be made soft.

  Based on the above results, when oil is mixed in each of the protection members 51 and 52, the oil mixed in each of the protection members 51 and 52 is non-functional as described above, and each of the protection members 51 and 52 is configured. It is in the state which is not couple | bonded with the gel member to do. For this reason, the oil moves through the protection members 51 and 52 and escapes from the second protection member 52 into the pressure medium.

  However, since the amount of oil mixed in the second protective member 52 is larger than that in the first protective member 51, even if the oil escapes from the second protective member 52 into the pressure medium, the second protective member 52 has the first protective member. A place where oil can move from 51 is not formed. Therefore, the movement of oil from the first protection member 51 to the second protection member 52 does not occur, and the movement of oil at the interface between the first protection member 51 and the second protection member 52 can be prevented. Thereby, since the oil amount of the 1st protection member 51 does not reduce, the 1st protection member 51 does not become hard and it can prevent the characteristic of sensor chip 20 from occurring.

  Furthermore, since the amount of oil mixed in the second protective member 52 is larger than that in the first protective member 51, the oil moves from the second protective member 52 to the first protective member 51. For this reason, the oil amount of the 1st protection member 51 can be increased with time, and the 1st protection member 51 can be made softer than the time of manufacture of a pressure sensor. That is, the second protection member 52 functions as an oil supply source to the first protection member 51. As described above, since the oil can be supplied from the second protection member 52 to the first protection member 51, the first protection member 51 can be prevented from becoming hard.

  Next, a method for manufacturing the pressure sensor will be described. First, the conductor part 11 is insert-molded, and the case 10 provided with the recess 12 and the pressure introducing hole 13 is formed by molding.

  On the other hand, a sensor chip 20 for pressure detection in which a concave portion 22 is provided and a diaphragm 21 as a distortion portion is formed is prepared. Also, a circuit chip 30 provided with a processing circuit formed by a semiconductor process or the like is prepared.

  Further, a pedestal 23 provided with a through hole 23a is prepared. And the sensor chip 20 and the base 23 are joined by anodic bonding, for example so that the back surface of the sensor chip 20 and the through-hole 23a of the base 23 may oppose.

  Subsequently, the base 23 is fixed to the recess 12 of the case 10. Specifically, the base 23 is bonded and fixed to the recess 12 of the case 10 so that the through hole 23 a of the base 23 and the pressure introducing hole 13 are connected. Thereby, the back surface of the sensor chip 20 is in a state of facing the pressure introduction hole 13 of the case 10. Further, the circuit chip 30 is bonded and fixed to the recess 12 of the case 10.

  Thereafter, wire bonding is performed between the sensor chip 20 and the conductor portion 11, between the circuit chip 30 and the conductor portion, and between the sensor chip 20 and the circuit chip 30. Thereby, the members are connected by the bonding wires 61 and 62.

  Next, the chip surface side protection member 40 and the chip back surface side protection member 50 are provided in the case 10. Specifically, the chip surface side protection member 40 is injected and filled into the recess 12 of the case 10. Further, the chip back surface side protection member 50 is injected and filled into the pressure introduction hole 13 of the case 10. As described above, after the case 10 is filled with the chip front surface side protection member 40 and the chip back surface side protection member 50, vacuum degassing is performed to prevent the generation of bubbles.

  When the pressure introduction hole 13 of the case 10 is filled with the chip back surface side protection member 50, the first protection member 51 and the second protection member 52 having different amounts of oil to be mixed are used. As described above, the liquid protective members 51, 52 are prepared by mixing different amounts of oil so that the amount of oil in the second protective member 52 is larger than that in the first protective member 51. In addition, the first protective member 51 is filled in the second hole 13 b of the pressure introducing hole 13. As a result, the first protective member 51 contacts the back surface of the sensor chip 20 and fills the through hole 23 a of the base 23. The first protective member 51 is filled up to the inside of the second hole 13 b of the pressure introducing hole 13. Next, the second protective member 52 is filled on the first protective member 51 in the second hole 13 b of the pressure introducing hole 13.

  Thereafter, the protection members 51 and 52 are cured by heating, whereby the arrangement of the protection members 51 and 52 is completed. In the arrangement of the first protective member 51 and the second protective member 52, the first protective member 51 may be filled and cured, and then the second protective member 52 may be filled and cured. It is preferable to cure simultaneously after filling the second protective member 52.

  In addition, in the chip | tip surface side protection member 40 and the chip | tip back surface side protection member 50, filling and hardening may be performed simultaneously, and you may carry out separately. Thus, the pressure sensor shown in FIG. 1 is completed.

  Next, a pressure detection method of the pressure sensor manufactured as described above will be described. First, the surface side pressure P <b> 1 is applied to the surface of the sensor chip 20 via the chip surface side protection member 40. On the other hand, the back side pressure P <b> 2 is applied from the pressure introducing hole 13 to the back side of the sensor chip 20 through the chip back side protection member 50.

  For example, when a pressure sensor is employed in the DPF system, the pressure on the upstream side of the exhaust gas filter is detected on the surface of the sensor chip 20 as the front surface side pressure P1, and the downstream side of the exhaust gas filter on the back surface of the sensor chip 20 as the back surface side pressure P2. Side pressure is detected. When the pressure sensor is employed as an intake pressure sensor, the atmospheric pressure is detected as the front surface pressure P1 on the surface of the sensor chip 20, and the intake pressure in the intake manifold is detected as the back surface pressure P2 on the back surface of the sensor chip 20. Is done.

  The diaphragm 21 of the sensor chip 20 is distorted by the pressure difference between the front surface side and the back surface side of the sensor chip 20, and an electrical signal at a level corresponding to this distortion is output from the sensor chip 20. This electric signal is processed by the circuit chip 30 and output from the conductor portion 11 to the outside of the pressure sensor.

  As described above, in the present embodiment, the first protection member 51 and the second protection member 52 constituting the chip back surface side protection member 50 disposed on the back surface side of the sensor chip 20 are in contact with the back surface of the sensor chip 20. It is characterized in that the amount of oil contained in the second protective member 52 in contact with the pressure medium is made larger than the amount of oil contained in the first protective member 51.

  Thereby, oil can always be supplied from the 2nd protection member 52 to the 1st protection member 51, and oil can escape from the 1st protection member 51, and the 1st protection member 51 can be prevented from becoming hard.

  In this case, even if the oil contained in the second protection member 52 escapes into the pressure medium, the amount of oil contained in the second protection member 52 is larger than that of the first protection member 51, so that the first The movement of oil from the protection member 51 to the second protection member 52 can be prevented, and the amount of oil in the first protection member 51 can be prevented from decreasing. Therefore, hardening of the 1st protection member 51 and the 2nd protection member 52 by oil omission can be avoided, and it can avoid affecting the characteristic of the sensor chip 20 by extension.

(Second Embodiment)
In the present embodiment, only different parts from the first embodiment will be described. In the first embodiment, the second protective member 52 that is an oil supply source and the first protective member 51 that is in contact with the back surface of the sensor chip 20 are made of the same material. Instead of the protective member 52, a plate containing oil is used.

  FIG. 4 is a schematic cross-sectional view of a pressure sensor according to the second embodiment of the present invention. As shown in this figure, in the pressure sensor, a sheet-like plate member 53 is disposed on the first protection member 51, and the chip back surface side protection member 50 is configured by the first protection member 51 and the plate member 53. Yes.

  The plate member 53 functions as an oil supply source including oil, and is made of, for example, a resin or rubber material. Further, similarly to the first embodiment, the amount of oil contained in the plate member 53 is larger than the amount of oil contained in the first protective member 51.

  The plate member 53 is disposed on the first protective member 51, and is in contact with the wall surface of the pressure introducing hole 13, but is not fixed. That is, the plate member 53 is in a state of floating on the surface of the first protection member 51.

  According to such a structure, the plate member 53 only slides in the pressure application direction when receiving pressure from the pressure medium. Further, even if the plate member 53 is thermally contracted, the plate member 53 itself does not generate stress and does not affect the characteristics of the sensor chip 20.

  When the pressure sensor shown in FIG. 2 is manufactured, when the chip back surface side protection member 50 is formed, the first protection member 51 and the plate member are arranged so that the oil amount of the plate member 53 is larger than that of the first protection member 51. 53 are prepared, and the first protective member 51 is filled in the pressure introducing hole 13. Thereafter, the plate member 53 is placed on the first protection member 51 and the first protection member 51 is cured. Thereby, the chip | tip back surface side protection member 50 can be formed. Thus, since it is only necessary to place the plate member 53 on the first protection member 51, the chip back surface side protection member 50 can be easily formed.

  Further, in the pressure sensor according to the present embodiment, the rubber member 14 that covers the adhesive portion between the bottom surface of the concave portion 12 of the case 10 and the base 23 and the connection portion between the bonding wire 61 and the conductor portion 11 is provided in the concave portion 12 of the case 10. Is provided. The rubber member 14 functions to suppress the generation of bubbles from the interface between the conductor portion 11 and the case 10 and is made of a material having a high elastic modulus and chemical resistance. . A chip surface side protection member 40 is provided on the rubber member 14. Such a rubber member 14 can also be employed in the pressure sensor shown in the first embodiment.

  As described above, the plate member 53 that supplies oil to the first protection member 51 can be employed as the configuration of the chip back surface side protection member 50. By using this plate member 53 as an oil supply source, it is possible to prevent the first protective member 51 from becoming hard, and as a result, the characteristics of the sensor chip 20 can be prevented from being affected.

(Third embodiment)
In the present embodiment, only different portions from the above embodiments will be described. In each of the above embodiments, the second protective member 52 and the plate member 53 are disposed on the first protective member 51 in the first hole 13a of the pressure introducing hole 13, but in the present embodiment, the first hole 13a. The first protective member 51 is characterized in that the first protective member 51 is disposed on the member serving as the oil supply source.

  FIG. 5 is a schematic cross-sectional view of a pressure sensor according to a third embodiment of the present invention. As shown in this figure, a hollow cylindrical pipe member 15 is disposed in the second hole 13 b of the pressure introducing hole 13 provided in the case 10. The outer diameter of the pipe member 15 is the same as the diameter of the second hole 13b, and is attached so that the outer wall of the pipe member 15 is in contact with the wall surface of the second hole 13b. The pipe member 15 has a length protruding from the second hole 13b toward the first hole 13a. As the material of the pipe member 15, for example, metal or ceramic is employed. The pipe member 15 corresponds to the bank portion of the present invention.

  Further, a rubber member 54 as an oil supply source is disposed in a region constituted by the outer wall of the pipe member 15 protruding into the first hole 13a and the wall surface of the first hole 13a. And the 1st protection member 51 is filled on the through-hole 23a of the base 23, the hollow part of the pipe member 15, and the rubber member 54 so that the back surface of the sensor chip 20 may be contact | connected. Thus, the first protective member 51 in contact with the back surface of the sensor chip 20 is in contact with the pressure medium, and the rubber member 54 as an oil supply source is completely covered with the first protective member 51. In the present embodiment, the first protection member 51 and the rubber member 54 constitute a chip back surface side protection member 50. The rubber member 54 corresponds to the oil supply member of the present invention.

  The pipe member 15 functions as an embankment for filling the rubber member 54 into the bottom surface of the first hole 13a. Instead of using the pipe member 15, the case 10 in which an embankment portion that projects into the first hole 13 a is provided in advance in the opening portion of the second hole 13 b may be employed.

  In the chip back surface side protection member 50 having such a configuration, the amount of oil contained in the rubber member 54 is larger than the amount of oil contained in the first protection member 51 in contact with the back surface of the sensor chip 20.

  Here, since the first protective member 51 in contact with the back surface of the sensor chip 20 is in contact with the pressure medium, the oil escapes from the first protective member 51. However, since oil is always supplied from the rubber member 54 in contact with the first protection member 51, the amount of oil contained in the first protection member 51 can be prevented from decreasing.

  Therefore, the first protective member 51 can be prevented from becoming hard even when the rubber member 54 as the oil supply source is covered with the first protective member 51 and the first protective member 51 is exposed to the pressure medium. The characteristics of the chip 20 can be prevented from being affected.

(Fourth embodiment)
In the present embodiment, only different parts from the first embodiment will be described. The present embodiment is characterized in that oil is directly supplied to the first protection member 51.

  FIG. 6 is a schematic cross-sectional view of a pressure sensor according to a fourth embodiment of the present invention. As shown in this figure, an oil supply chamber 16 is provided in the case 10, and a liquid oil 17 is disposed in the oil supply chamber 16. The oil 17 is put into the oil supply chamber 16 from a supply port 18 provided on one surface of the plate forming the case 10.

  Further, the oil supply chamber 16 and the first hole 13 a of the pressure introducing hole 13 are connected by a passage 19 provided in the case 10. Thereby, when the first protective member 51 is filled in the first hole 13 a and the oil 17 is put into the oil supply chamber 16, the oil 17 comes into direct contact with the first protective member 51.

  According to such a configuration, the first protection member 51 is supplied with oil from the second protection member 52, while the oil 17 is directly supplied from the oil supply chamber 16 through the passage 19. Therefore, the amount of oil contained in the first protection member 51 does not decrease, and the first protection member 51 becomes softer than that when the pressure sensor is completed depending on the amount of oil supplied.

  As described above, the oil supply chamber 16 is provided in the case 10 so that the oil 17 is in direct contact with the first protective member 51, so that the oil 17 is not only supplied from the second protective member 52 but also the first protective member 51. Can be supplied to.

  In this case, since the oil 17 can be directly supplied to the first protection member 51, the amount of oil contained in each of the first protection member 51 and the second protection member 52 may be the same. Further, the oil supply chamber 16 shown in the present embodiment can also be employed in the pressure sensor shown in FIGS. In the pressure sensor shown in FIG. 5, the oil 17 can be in direct contact with the rubber member 54.

(Fifth embodiment)
In the present embodiment, only different portions from the above embodiments will be described. In each of the above embodiments, the pressure sensor is configured to detect a differential pressure between the pressures received on the front surface and the back surface of the sensor chip 20, but the contents of the invention described above are applied to the pressure sensor that detects the absolute pressure. Can be applied.

  FIG. 7 is a partial schematic cross-sectional view of the pressure sensor according to the fifth embodiment of the present invention, and is an enlarged view of the vicinity of the sensor chip 70. In the pressure sensor, for example, a recess 81 is provided in a case 80, and a sensor chip 70 is fixed to the bottom surface of the recess 81 via a glass pedestal 71. Each input / output terminal (not shown) of the sensor chip 70 is insert-molded in the case 80 and is electrically connected to one end side of the terminal 82 exposed on the bottom surface of the recess 81 via a bonding wire 83. Yes.

  The sensor chip 70 has a plate shape and is configured to detect absolute pressure. That is, one surface of the plate constituting the sensor chip 70 is a pressure receiving surface, and the other surface of the plate is a surface that detects a vacuum pressure that is a reference pressure.

  Further, a rubber member 55 is provided at the bottom of the concave portion 81 of the case 80 so as to cover the connection portion between the terminal 82 and the bonding wire 83 and its peripheral portion. A first protective member 51 that contacts the pressure receiving surface of the sensor chip 70 is laminated on the upper surface of the rubber member 55, and a second protective member 52 is provided on the first protective member 51.

  Also in the pressure sensor having such a configuration, the amount of oil contained in the second protective member 52 in contact with the pressure medium is made larger than the amount of oil contained in the first protective member 51 in contact with the pressure receiving surface of the sensor chip 70. The oil can be supplied from the second protective member 52 to the first protective member 51, and the first protective member 51 can be prevented from curing.

(Sixth embodiment)
In the present embodiment, only parts different from the fifth embodiment will be described. FIG. 8 is a partial schematic cross-sectional view of a pressure sensor according to a sixth embodiment of the present invention. As shown in this figure, a plate member 53 in which more oil than the first protection member 51 is mixed is disposed on the first protection member 51. Thus, in the pressure sensor for measuring the absolute pressure, the plate member 53 can be adopted.

(Seventh embodiment)
In the present embodiment, only parts different from the fifth and sixth embodiments will be described. FIG. 9 is a partial schematic cross-sectional view of a pressure sensor according to a seventh embodiment of the present invention. In the present embodiment, the rubber member 55 is supplied with oil by increasing the amount of oil contained in the lower rubber member 55 than the first protective member 51 in contact with the pressure receiving surface of the sensor chip 70. It functions as a source. Thus, the rubber member 55 covered with the first protective member 51 can be used as an oil supply source. The rubber member 55 according to the present embodiment corresponds to the oil supply member of the present invention.

(Other embodiments)
The form of the pressure sensor shown in each of the above embodiments is merely an example, and the present invention is not limited to these, and other forms may be used.

  In each of the above embodiments, a gel member is employed as the second protection member 52 of the chip back surface side protection member 50, but it is also possible to use a resin material such as rubber, for example. Even in this case, the amount of oil mixed in the second protective member 52 may be larger than that of the first protective member 51.

  In each of the above embodiments, the chip back surface side protection member 50 has been described as having a two-layer structure, but it may be three or more layers. In this case, at least the amount of oil contained in the second protective member in contact with the first protective member may be larger than the amount of oil contained in the first protective member in contact with the sensor chip 20.

  Moreover, in the said 1st-4th embodiment, although only the chip | tip back surface side protection member 50 is comprised by the protection members 51 and 52 containing oil, each chip | tip surface side protection member 40 is each protection member containing oil. 51 and 52 may be comprised. In this case, the chip surface side protection member 40 can also be constituted by a plurality of protection members as described above.

  The oil supply chamber 16 shown in the fourth embodiment can be provided for the pressure sensor that detects the absolute pressure shown in the fifth to seventh embodiments. Thereby, since the oil 17 in the oil supply chamber 16 directly contacts the first protection member 51 provided in the recess 81, the oil 17 can be used as an oil supply source for the first protection member 51. In this case, in the pressure sensor shown in FIG. 9 in the seventh embodiment, the oil 17 can be in direct contact with the rubber member 55.

It is a schematic sectional drawing of the pressure sensor which concerns on 1st Embodiment of this invention. It is the figure which showed the correlation of the weight loss at the time of heating the protection member of oil concentration X, and time. It is the figure which showed the correlation with the increase weight of the protection member replenished with oil, and time. It is a schematic sectional drawing of the pressure sensor which concerns on 2nd Embodiment of this invention. It is a schematic sectional drawing of the pressure sensor which concerns on 3rd Embodiment of this invention. It is a schematic sectional drawing of the pressure sensor which concerns on 4th Embodiment of this invention. It is a partial schematic sectional drawing of the pressure sensor which concerns on 5th Embodiment of this invention. It is a partial schematic sectional drawing of the pressure sensor which concerns on 6th Embodiment of this invention. It is a partial schematic sectional drawing of the pressure sensor which concerns on 7th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 80 ... Case, 12, 81 ... Case recessed part, 13 ... Pressure introduction hole, 13a ... 1st hole, 13b ... 2nd hole, 15 ... Pipe member, 16 ... Oil supply chamber, 17 ... Oil, 19 ... Passage 20, 70 ... sensor chip, 50 ... chip back side protection member, 51 ... first protection member, 52 ... second protection member, 53 ... plate member, 54, 55 ... rubber member.

Claims (6)

A sensor chip (20, 70) having a pressure receiving surface, which detects the pressure of the pressure medium by the pressure receiving surface and generates an electrical signal corresponding to the pressure medium, is provided with a plurality of protective members (oil members mixed) 50) a pressure sensor that is covered and protected,
Among the plurality of protective members (50), at least the first protective member (50) is more than the amount of oil material contained in the first protective member (51) in contact with the pressure receiving surface of the sensor chip (20, 70). 51) The amount of oil material contained in the second protective member (52) in contact with the second protective member (52) is increased, and the second protective member (52) is an oil supply source of the first protective member (51) ,
A plate-shaped member having one surface and the other surface, wherein a recess (12) is formed on the one surface, and a pressure introducing hole (13) penetrating the bottom surface of the recess (12) and the other surface is formed. A case (10),
The sensor chip (20) has a plate-like shape having one surface and another surface, and the one surface and the other surface are pressure receiving surfaces, and differential pressures of pressure applied to the pressure receiving surfaces, respectively. Is disposed in the recess (12) so that one of the pressure receiving surfaces faces the pressure introduction hole (13) of the case (10),
The plurality of protection members (50) are configured by only two layers of the first protection member (51) and the second protection member (52), and the first protection member (51) is the sensor chip (20). ) Is filled in the pressure introducing hole (13) so as to be in contact with one of the pressure receiving surfaces, and the second protective member (52) is in the pressure introducing hole (13), and the first protective member ( 51) A pressure sensor which is arranged on top of . The second protective member (52) has a sheet shape including an oil material, and is configured as a plate member (53) disposed on the first protective member (51). The pressure sensor according to claim 1 . An oil supply chamber (16) in which liquid oil (17) is disposed in the case (10) is provided, and the oil (17) is supplied from the oil supply chamber (16) to the pressure introducing hole (13). Through the passage (19) leading to the first protective member (51) disposed in the pressure introducing hole (13), and the oil (17) is in contact with the first protective member (51). The pressure sensor according to claim 1 , wherein the pressure sensor is an oil supply source. A sensor chip (20, 70) having a pressure receiving surface, which detects the pressure of the pressure medium by the pressure receiving surface and generates an electrical signal corresponding to the pressure medium, is provided with a plurality of protective members (oil members mixed) 50) a pressure sensor that is covered and protected,
Among the plurality of protective members (50), at least the first protective member (50) is more than the amount of oil material contained in the first protective member (51) in contact with the pressure receiving surface of the sensor chip (20, 70). 51) The amount of oil material contained in the second protective member (52) in contact with the second protective member (52) is increased, and the second protective member (52) is an oil supply source of the first protective member (51) ,
A case (80) having a recess (81),
The sensor chip (70) is a plate having a pressure receiving surface, and is disposed in the recess (81) so as to detect the pressure applied to the pressure receiving surface as an absolute pressure,
The plurality of protection members (50) are configured by only two layers of the first protection member (51) and the second protection member (52), and the first protection member (51) is the sensor chip (20). ) Is filled in the concave portion (81) so as to be in contact with one of the pressure-receiving surfaces of the second pressure member, and the second protective member (52) is in the concave portion (81) and above the first protective member (51). A pressure sensor characterized by being arranged in The second protective member (52) has a sheet shape including an oil material, and is configured as a plate member (53) disposed on the first protective member (51). The pressure sensor according to claim 4 . An oil supply chamber (16) in which liquid oil (17) is disposed is provided in the case (80), and the oil (17) communicates from the oil supply chamber (16) to the recess (81). The oil (17) is in direct contact with the first protection member (51) disposed in the recess (81) through the passage (19), and the oil (17) is an oil supply source for the first protection member (51). The pressure sensor according to claim 4 , wherein the pressure sensor is configured as follows.

Images