JP6384405B2 - Sensor device - Google Patents

Description

  The present invention relates to a sensor device that detects pressure.

  As shown in Patent Document 1, a sensor chip, a terminal connected to the sensor chip, a case for housing the sensor chip and each of the terminals, a housing in which an introduction hole for flowing a fluid to be detected is formed, There is known a mechanical quantity sensor comprising:

Japanese Patent No. 5278387

  In the above-mentioned Patent Document 1, the case is assembled to the housing so that a part of the sensor chip is exposed to the outside of the case and the exposed part is installed in the introduction hole. Therefore, in the case of this configuration, a part of the sensor chip exposed from the case and the wall surface forming the introduction hole face each other with a predetermined interval, and thus the wall surface and the sensor chip may be electrostatically coupled. When the sensor chip and the housing are electrostatically coupled in this way, current may flow to the housing via the sensor chip.

  The terminal described in Patent Document 1 includes an island to which a sensor chip is fixed and a connection terminal that is electrically connected to the sensor chip. Therefore, when external noise is duplicated on the connection terminal, the external noise flows to the housing via the sensor chip, which may reduce the detection accuracy of the mechanical quantity (pressure) of the sensor chip.

  In view of the above problems, an object of the present invention is to provide a sensor device in which a decrease in pressure detection accuracy is suppressed.

One of the disclosed inventions for achieving the above object includes a sensor chip (20) for detecting pressure,
An island (45) that cantilever-supports the sensor chip;
A lead (40) electrically connected to the sensor chip;
A mold resin (50) covering each of the support end supported by the island in the sensor chip, the island, and the electrical connection portion of the lead with the sensor chip;
A housing (90) for fixing the mold resin to the mounted member,
The housing is conductive and has a cylindrical shape, and a part of its inner surface is connected to the mold resin by contacting the outer surface of the mold resin. Encloses the free end (20a) opposite the support end exposed from the resin;
The island is electrically connected to the lead,
The island has an extended portion (47-49) extending from the support end toward the free end,
The extending portion is closer to the housing than the sensor chip so that the electrostatic coupling between the extending portion and the housing is stronger than the electrostatic coupling between the sensor chip and the housing.

  As described above, according to the present invention, rather than the electrostatic coupling between the sensor chip (20) and the housing (90), the electrostatic force between the extended portion (47 to 49) (the island (45)) and the housing (90) can be reduced. Bonding is stronger. Therefore, even if noise is overlapped on the lead (40), the noise can be passed to the housing (90) through the island (45). As a result, noise flows to the sensor chip (20), thereby suppressing a decrease in pressure detection accuracy.

  In addition, the code | symbol with the parenthesis is attached | subjected to the element as described in the claim as described in a claim, and each means for solving a subject. The reference numerals in parentheses are for simply indicating the correspondence with each component described in the embodiment, and do not necessarily indicate the element itself described in the embodiment. The description of the reference numerals with parentheses does not unnecessarily narrow the scope of the claims.

It is sectional drawing which shows schematic structure of the sensor apparatus which concerns on 1st Embodiment. It is sectional drawing which shows schematic structure of the sensor part of FIG. It is a fragmentary sectional view which shows the positional relationship of a sensor chip and a housing. It is the schematic which shows the positional relationship of the sensor chip, the extension part, and the housing seen from the outline arrow direction of FIG. It is a fragmentary sectional view for explaining the extension part concerning a 2nd embodiment. It is a fragmentary sectional view for explaining the extension part concerning a 3rd embodiment. It is a fragmentary sectional view which shows the modification of an extending part. It is a fragmentary sectional view showing the modification of mold resin. It is a fragmentary sectional view showing the modification of mold resin. It is sectional drawing which shows the modification of a lead.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
The sensor device according to the present embodiment will be described with reference to FIGS. In order to clarify the configuration, the island 45 and the lead 40 are hatched in FIG. 2, and the island 45 and the housing 90 are hatched in FIG.

  Hereinafter, the three directions orthogonal to each other are referred to as an x direction, a y direction, and a z direction. A plane defined by the x direction and the y direction is an xy plane, a plane defined by the y direction and the z direction is a yz plane, and a plane defined by the z direction and the x direction is a zx plane. It shows.

  As shown in FIG. 1, the sensor device 100 includes a sensor unit 10, a connector 60, and a housing 90. The sensor unit 10 and the connector 60 are mechanically and electrically connected, and the connector 60 and the housing 90 are mechanically connected. The housing 90 is fixed to a member to be attached such as a pipe made of metal, and a part of the sensor chip 20 of the sensor unit 10 is exposed to a medium to be measured flowing in the pipe. The pressure of the medium to be measured is converted into an electrical signal by the sensor chip 20, and the electrical signal is output via the connector 60 to an external device such as an electronic control device. Hereinafter, the sensor unit 10, the connector 60, and the housing 90 will be described in detail.

  As shown in FIGS. 1 and 2, the sensor unit 10 includes a sensor chip 20, a circuit chip 30, leads 40, islands 45, and a mold resin 50. Each of the sensor chip 20 and the circuit chip 30 is mounted on the island 45 and is electrically connected to each other via the first wire 11. The circuit chip 30 and the lead 40 are electrically connected via the second wire 12. The support end of the sensor chip 20 with the island 45, the circuit chip 30, the connection end of the lead 40 with the circuit chip 30, the connection part of the chips 20 and 30, and the connection part of the lead 40 are integrated with the mold resin 50. Is covered.

  The sensor chip 20 includes a semiconductor substrate 21 and a piezoresistive element 22 formed on the semiconductor substrate 21. As shown in FIGS. 1 and 2, a thin portion 23 having a thin thickness is locally formed on the semiconductor substrate 21, and four piezoresistive elements 22 are formed therein. Two of these four piezoresistive elements 22 constitute a first half bridge circuit, and the remaining two constitute a second half bridge circuit. These two half-bridge circuits are connected to form a full-bridge circuit. A constant current circuit is connected to one end of the full bridge circuit, and the other end is fixed to the ground potential. When the thin portion 23 is distorted by the pressure of the medium to be measured, the resistance value of the piezoresistive element 22 changes accordingly. Then, the midpoint potential of each of the two half-bridge circuits changes. This midpoint potential is output to the circuit chip 30 as an electrical signal corresponding to the pressure of the medium to be measured.

  As shown in FIG. 2, the sensor chip 20 and the circuit chip 30 are electrically connected via five first wires 11. One of the five first wires 11 functions to supply the ground potential to the bridge circuit, and the other one functions to supply the constant current described above. The other two first wires 11 function to output the midpoint potential of the two half-bridge circuits to the circuit chip 30, and the last one first wire 11 fixes the potential of the sensor chip 20. The function of supplying a voltage of 2 to the sensor chip 20 is achieved.

  The circuit chip 30 is formed by forming a processing circuit for processing an electric signal output from the sensor chip 20 and the constant current circuit on a semiconductor substrate. The processing circuit includes a filter that removes noise included in the midpoint potential of the two half-bridge circuits, and a differential amplifier circuit that differentially amplifies the two midpoint potentials via the filter. Further, the processing circuit has a monitoring circuit that monitors a constant current supplied from the constant current circuit to the sensor chip 20. This monitoring circuit detects the temperature of the sensor chip according to the fluctuation of the constant current.

  As shown in FIG. 2, the circuit chip 30 and the leads 40 are electrically connected via the four second wires 12. One of the four second wires 12 functions to supply a ground potential to the circuit chip, and the other one functions to supply a power supply voltage. One of the remaining two second wires 12 functions to output a differentially amplified midpoint potential (a detection signal corresponding to the pressure of the measured medium) to the lead 40. The last one functions to output a detection signal corresponding to the temperature to the lead 40.

  The lead 40 has four leads 41 to 44. The first lead 41 is fixed to the ground, and the power supply voltage is supplied to the second lead 42. The third lead 43 outputs a detection signal corresponding to the pressure of the medium to be measured to the electronic control unit, and the fourth lead 44 outputs a detection signal corresponding to the temperature to the electronic control unit.

  As shown in FIG. 2, an island 45 is integrally connected to one end of the first lead 41. The island 45 has a shape whose length in the x direction is wider than each of the leads 41 to 44 in the xy plane, and all of the back surface of the circuit chip 30 and a part of the back surface of the sensor chip 20 are formed on the island 45. Installed. As described above, the island 45 and the first lead 41 are connected. Therefore, the island 45 is fixed at the ground potential.

  As shown in FIG. 2, chip leads 46 for removing noise are mounted on the leads 41-44. One end of the chip capacitor 46 is connected to the first lead 41, and the other end is connected to any one of the other leads 42 to 44. In this way, by bridging the first lead 41 and the other leads 42 to 44 via the chip capacitor 46, the noise included in the electrical signals of the leads 42 to 44 flows to the first lead 41 (ground). It has become.

  The mold resin 50 covers the sensor chip 20, the circuit chip 30, and the leads 40 so as to integrally connect them. The sensor chip 20 is cantilevered on the island 45 through the adhesive 24, and the circuit chip 30 is fixed to the island 45 through the adhesive 31. As described above, the sensor chip 20 and the circuit chip 30 are electrically connected via the first wire 11, and the circuit chip 30 and the lead 40 are electrically connected via the second wire 12. The mold resin 50 integrally covers the connection end of the sensor chip 20 with the island 45, the circuit chip 30, and the connection end of the lead 40 with the circuit chip 30. The detection end 20 a where the thin portion 23 and the piezoresistive element 22 in the sensor chip 20 are formed, and the connection end opposite to the connection end in the lead 40 are exposed to the outside of the mold resin 50. As shown in FIG. 2, a part of the mold resin 50 has an annular shape so as to surround the detection end 20 a of the sensor chip 20. The detection end 20a corresponds to a free end described in the claims.

  The connector 60 is electrically connected to the lead 40 and is electrically connected to the electronic control device via a connector cable. The connector 60 has a plurality of external connection terminals 61 having one end electrically connected to the connecting end of the lead 40 and the other end electrically connected to the connector cable.

  The connector 60 also includes a cover portion 62 that integrally connects the plurality of external connection terminals 61. As shown in FIG. 1, the cover portion 62 has a column shape extending in the y direction, and annular surrounding portions 63 and 64 are formed at both ends thereof. The end of the external connection terminal 61 is exposed from one end of the cover part 62 and is surrounded by the first surrounding part 63. The other end of the cover 62 is formed with a recess 65 for fitting the connecting end of the lead 40 and the rear part of the mold resin 50 from which the lead 40 protrudes. The sensor unit 10 fitted in the recess 65 is surrounded by a second surrounding portion 64.

  Although not shown, the cover portion 62 is also formed with an opening for electrically connecting the lead 40 and the external connection terminal 61. The sensor unit 10 is fitted into the recess 65 and the lead 40 and the external connection terminal 61 are electrically and mechanically connected through the opening, and then the opening is closed with a resin material. By doing so, the sensor unit 10 and the connector 60 are mechanically and electrically connected. The mold resin 50 and the cover part 62 correspond to the mold resin described in the claims.

  An annular space formed between the mold resin 50 and the second surrounding portion 64 in order to suppress the pressure medium from entering the gap between the outer surface of the mold resin 50 and the wall surface constituting the recess 65. The potting material 66 is filled.

  The housing 90 fixes the connector 60 to the pipe. The housing 90 has a cylindrical shape and is made of a metal material. The housing 90 includes a first tube portion 91, a second tube portion 92 having a shorter diameter than the first tube portion 91, and a connecting portion 93 that integrally connects the first tube portion 91 and the second tube portion 92. Have. Each of the cylindrical portions 91 and 92 extends in the y direction, and the connecting portion 93 has an annular shape in the zx plane. The end portion of the first tube portion 91 is connected to the outer ring surface of the connection portion 93, and the end portion of the second tube portion 92 is connected to the inner ring surface of the connection portion 93.

  As shown in FIG. 1, the inner surface of the first cylindrical portion 91 is in contact with the outer surface of the second surrounding portion 64, and the inner surface of the connecting portion 93 is in contact with the end surface of the second surrounding portion 64. The detection end 20 a of the sensor chip 20 exposed to the outside from the mold resin 50 is located in the internal space formed by the second cylindrical portion 92. The inner surface of the second cylindrical portion 92 corresponds to a non-contact portion described in the claims.

  When the housing 90 is coupled to the connector 60 to which the sensor unit 10 is connected, the following procedure is performed. First, the tip of the sensor unit 10 (annular portion surrounding the detection end 20a in the mold resin 50) is located in the internal space of the second cylinder 92, and the inner surface of the first cylinder 91 and the outer surface of the second enclosure 64 The connector 60 and the sensor unit 10 are inserted into the housing 90 so that they contact each other. Thereafter, as shown by a curved arrow in FIG. 1, the end of the first cylindrical portion 91 is caulked toward the connector 60. By doing so, the housing 90 is coupled to the connector 60.

  In order to prevent the pressure medium from being discharged from the inside of the pipe to the outside through the gap between the housing 90 and the connector 60, the inner surface of the connecting portion 93 and the end surface of the second surrounding portion 64 are connected. An O-ring 94 is provided therebetween. An annular groove in the xy plane is formed at the end of the second surrounding portion 64, and an O-ring 94 is provided in this groove. The O-ring 94 is pressed in the y direction by caulking the end portion of the first cylindrical portion 91 described above. As a result, the gap between the housing 90 and the cover portion 62 is sealed by the O-ring 94.

  On the outer surface of the second cylinder portion 92, a screw groove 92a for screwing to the wall portion of the pipe is formed. When the housing 90 is screwed to the pipe, the housing 90 and the pipe are electrically connected. As a result, the housing 90 is grounded.

  Next, the island 45 of the lead 40 will be described in detail. As shown in FIG. 2, the island 45 has a rectangular shape in the xy plane. The island 45 is formed with two extending portions 47 and 48 extending along the y direction so as to approach the sensor chip 20. As shown in FIG. 3, each of the two extending portions 47 and 48 is located in the internal space of the second cylindrical portion 92 together with the detection end 20 a of the sensor chip 20, and is surrounded by the inner surface thereof. As shown in FIG. 4, the distance d2 between the two extending portions 47 and 48 and the inner surface is shorter than the distance d1 between the sensor chip 20 and the inner surface. Thereby, the electrostatic coupling between the extending portions 47 and 48 (first lead 41) and the housing 90 is stronger than the electrostatic coupling between the sensor chip 20 and the housing 90.

  As shown in FIG. 4, the facing surface S <b> 1 between the sensor chip 20 and the housing 90 is larger than the facing surface S <b> 2 between the extending portions 47 and 48 and the housing 90. However, what substantially contributes to the electrostatic coupling described above is the facing area between the housing 90 and the conductive surface formed on the sensor chip 20 in the facing surface S1, which is larger than the facing surface S2. It is narrower. Therefore, the electrostatic coupling between the extending portions 47 and 48 (first lead 41) and the housing 90 is stronger than the electrostatic coupling between the sensor chip 20 and the housing 90. In other words, the capacitance formed by the extending portions 47 and 48 (first lead 41) and the housing 90 is larger than the capacitance formed by the sensor chip 20 and the housing 90. Yes.

  Next, functions and effects of the sensor device 100 according to the present embodiment will be described. As described above, the electrostatic coupling between the extending portions 47 and 48 (the island 45) and the housing 90 is stronger than the electrostatic coupling between the sensor chip 20 and the housing 90. Therefore, even if noise is overlapped on the lead 40, the noise can flow to the housing 90 via the extending portions 47 and 48. That is, noise can be caused to flow through the wall portion of the pipe that is the member to be attached. As a result, noise flows to the sensor chip 20 and the circuit chip 30, thereby reducing the pressure detection accuracy. Moreover, it is suppressed that the temperature detection accuracy falls.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In the following, description of common parts is omitted, and different parts are mainly described. The same applies to other embodiments.

  In the first embodiment, as shown in FIG. 3, the example in which the lengths in the y direction of the two extending portions 47 and 48 are equal is shown. On the other hand, this embodiment is characterized in that the lengths of the two extending portions 47 and 48 in the y direction are different.

  According to this, the facing area between the first extending portion 47 and the housing 90 is different from the facing area between the second extending portion 48 and the housing 90. Therefore, the first capacitance constituted by the first extending portion 47 and the housing 90 is different from the second capacitance constituted by the second extending portion 48 and the housing 90. Therefore, noises having different frequency bands can flow to the housing 90 by these two capacitances.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, as shown in FIG. 3, an example in which the length (width) in the x direction of each of the two extending portions 47 and 48 is constant has been described. On the other hand, this embodiment is characterized in that each of the two extending portions 47 and 48 has a shape protruding toward the housing 90. That is, as shown in FIG. 6, each of the two extending portions 47 and 48 is longer in the x direction by d3 than the extending portions 47 and 48 described in the first embodiment. The separation distance from is shortened. According to this, the electrostatic coupling between the extending portions 47 and 48 and the housing 90 can be further strengthened.

  In the present embodiment, an example is shown in which the lengths of the two extending portions 47 and 48 in the x direction are equal to each other and are increased by d3. However, the lengths of the extending portions 47 and 48 in the x direction may be different from each other. According to this, since the first capacitance and the second capacitance described in the second embodiment are different, noises having different frequency bands can be caused to flow to the housing 90 by these two capacitances. .

  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.

(First modification)
In each embodiment, the example in which the extending portions 47 and 48 extending in the y direction are formed on the island 45 is shown. However, as shown in FIG. 7, the extending portions 47 and 48 extending in the y direction may be connected to each other by a third extending portion 49 extending in the x direction to form a ring as a whole.

(Second modification)
In each embodiment, the example in which a part of the mold resin 50 has an annular shape so as to surround the detection end 20a of the sensor chip 20 has been described. As shown in FIG. 3, an example in which a part of the annular mold resin 50 covers the extended portions 47 and 48 is shown. However, as shown in FIGS. 8 and 9, the portions covering the extended portions 47 and 48 in the mold resin 50 do not have to be annular. As shown in FIG. 8, only the extending portions 47 and 48 may be covered. Alternatively, as shown in FIG. 9, a part of the mold resin 50 may be formed so as to incline from the tip portions of the extending portions 47 and 48 toward the sensor chip 20 side. This facilitates insertion of the sensor unit 10 into the housing 90.

(Third Modification)
Although not shown, a configuration in which the outer surface of the portion covering the extended portions 47 and 48 in the mold resin 50 is in contact with the inner surface of the second cylindrical portion 92 may be employed. According to this, since only the mold resin 50 is provided between the extending portions 47 and 48 and the second cylindrical portion 92, the strength of electrostatic coupling between the extending portions 47 and 48 and the housing 90 is reduced. It becomes easy to calculate. Strictly speaking, there is always a gap between the extended portions 47 and 48 and the second cylindrical portion 92. Therefore, a medium to be detected exists between the two in addition to the mold resin 50. However, as described above, the portion of the mold resin 50 that covers the extended portions 47 and 48 and the inner surface of the second cylindrical portion 92 are in contact with each other, so ignore the detected medium when calculating the electrostatic coupling. Even if it calculates, it is suppressed that the calculation precision falls remarkably. It is also possible to adopt a configuration in which a conductive member is formed on the outer surface of the portion covering the extended portions 47 and 48 in the mold resin 50 and the inner surface of the second cylindrical portion 92 is in contact with the conductive member. This can also increase the strength of electrostatic coupling.

(Other variations)
In the present embodiment, an example in which the island 45 and the first lead 41 are integrally connected is shown. However, as shown in FIG. 10, the island 45 and the first lead 41 may be separated. In this case, the island 45 and the first lead 41 are electrically connected via the second wire 12 and the third wire 13.

  In the present embodiment, an example in which the island 45 and the first lead 41 are electrically connected is shown. However, the island 45 and the second lead 42 may be electrically connected. In this case, the island 45 and the second lead 42 may be integrally connected. Further, the island 45 and the second lead 42 may be separated. However, in this case, the island 45 and the second lead 42 are electrically connected via the second wire 12 and the third wire 13.

  In the present embodiment, an example in which four piezoresistive elements 22 are formed in the thin portion 23 and a full bridge circuit is formed by these is shown. However, it is also possible to adopt a configuration in which two piezoresistive elements 22 are formed in the thin portion 23 and thereby a half bridge circuit is formed.

  In the present embodiment, an example in which the chip capacitor 46 is mounted on the leads 41 to 44 is shown. However, the chip capacitor 46 may not be provided.

  In the present embodiment, an example in which the sensor chip 20 is cantilevered on the island 45 via the adhesive 24 is shown. However, a configuration in which the sensor chip 20 is cantilevered by the island 45 via bumps may be employed.

DESCRIPTION OF SYMBOLS 20 ... Sensor chip, 20a ... Free end, 40 ... Lead, 45 ... Island, 47 ... 1st extending part, 48 ... 2nd extending part, 49 ... 3rd extending part, 50 ... Mold resin, 90 ... Housing , 100 ... Sensor device

Claims (11)

A sensor chip (20) for detecting pressure;
An island (45) for cantilevering the sensor chip;
A lead (40) electrically connected to the sensor chip;
A mold resin (50) for covering each of the electrical connection sites of the sensor chip in the support end, the island, and the lead that are supported by the island in the sensor chip;
A housing (90) for fixing the mold resin to the attached member,
The housing has conductivity and forms a cylindrical shape, and a part of the inner surface thereof is connected to the mold resin by contacting the outer surface of the mold resin, and a non-contact portion of the inner surface with the mold resin is provided. , Surrounding the free end (20a) opposite to the support end exposed from the mold resin in the sensor chip,
The island is electrically connected to the lead;
The island has an extending portion (47 to 49) extending from the support end toward the free end,
The extension portion is closer to the housing than the sensor chip so that the electrostatic coupling between the extension portion and the housing is stronger than the electrostatic coupling between the sensor chip and the housing. apparatus. As the extension part, it has a first extension part (47) and a second extension part (48),
The sensor device according to claim 1, wherein the first extending portion is longer in a direction from the support end toward the free end than the second extending portion.   The sensor device according to claim 1, wherein the extending portion (47 to 49) has an annular shape.   The sensor device according to any one of claims 1 to 3, wherein the extending portion (47, 48) protrudes toward the non-contact portion.   The sensor chip includes: a piezoresistive element (22) that converts a pressure of a medium to be measured in a space surrounded by the non-contact portion into an electric signal; and a substrate (21) on which the piezoresistive element is formed. The sensor device according to any one of claims 1 to 4.   The sensor device according to claim 5, wherein a thin portion (23) having a locally thin thickness is formed on the substrate, and the piezoresistive element is formed in the thin portion.   As the leads, a first lead (41) fixed to the ground potential, a second lead (42) to which a power supply voltage is supplied, and a third lead (outputting the electrical signal of the piezoresistive element) to an external device ( 43) The sensor device according to claim 5 or 6, comprising: 43).   The sensor device according to claim 7, wherein the island and the first lead are electrically connected.   The sensor device according to claim 8, wherein the island and the first lead are mechanically integrally connected.   The sensor device according to claim 7, wherein the island and the second lead are electrically connected.   The sensor device according to claim 10, wherein the island and the second lead are mechanically integrally connected.

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