Inertial Measurement Unit

Abstract

To provide an inertial measurement device with excellent detection accuracy.SOLUTION: An inertial measurement device 1 includes: an inertial sensor module 4 having a first inertial sensor 100 and having an external shape molded from a first resin 9; a component 6; a second resin 8 that molds the inertial sensor module 4 and the component 6; and metal 5 provided between the first resin 9 and the second resin 8 of the inertial sensor module 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to inertial measurement units. [Background technology]

[0002] In recent years, inertial sensors manufactured using MEMS (Micro Electro Mechanical Systems) technology have been developed. For example, Patent Document 1 discloses a sensor unit using such an inertial sensor, which includes a sensor device including an inertial sensor sealed with a sealing resin and electrodes connected to the inertial sensor and disposed on the outer surface of the sealing resin, a substrate to which the sensor device is bonded, a case member that houses the sensor device, and an adhesive member that connects the sensor device to the case member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-49122 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the inertial sensor described in Patent Document 1 is sealed with a sealing resin, and an adhesive member is disposed on the outside of this, so there is a risk that moisture in the adhesive member may affect the measurement of the sensor device. [Means for solving the problem]

[0005] The inertial measurement device has a first inertial sensor, an inertial sensor module whose outer shape is molded from a first resin, components, a second resin that molds the inertial sensor module and the components, and a metal provided between the first resin and the second resin of the inertial sensor module. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a plan view showing a schematic structure of an inertial measurement unit according to a first embodiment. [Figure 2] FIG. 2 is a side view of the inertial measurement unit of FIG. 1. [Figure 3] FIG. 2 is a plan view showing a schematic structure of the inertial sensor module shown in FIG. [Figure 4] 4 is a cross-sectional view taken along line AA in FIG. 3. [Figure 5] FIG. 4 is a cross-sectional view taken along line BB in FIG. 3 . [Figure 6] FIG. 2 is a plan view showing a schematic structure of a second inertial sensor in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line CC in FIG. [Figure 8] FIG. 10 is a plan view showing a schematic structure of an inertial measurement unit according to a second embodiment. [Figure 9] FIG. 9 is a side view of the inertial measurement unit of FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0007] 1. First embodiment First, an inertial measurement unit 1 according to a first embodiment will be described with reference to FIGS.

[0008] For ease of explanation, Figures 1 and 2 omit the illustration of the wiring electrically connecting the semiconductor element 50 formed on the base substrate 2 to the lead terminals 3, and the wiring electrically connecting the semiconductor element 50 to the inertial sensor module 4 and each component 6.

[0009] In the following plan views, side views, and cross-sectional views, three mutually orthogonal axes, the X-axis, the Y-axis, and the Z-axis, are illustrated. In this specification, the first axis is the X-axis, the second axis is the Y-axis, and the third axis is the Z-axis. The direction along the X-axis is referred to as the "X-direction," the direction along the Y-axis is referred to as the "Y-direction," and the direction along the Z-axis is referred to as the "Z-direction." The tip of the arrow in each axial direction is also referred to as the "plus side," the base end as the "minus side," the plus side of the Z direction as "up," and the minus side of the Z direction as "down." The Z-direction is along the vertical direction, and the XY plane is along the horizontal plane. In this specification, the plus and minus directions are collectively referred to as the X-direction, the Y-direction, and the Z-direction.

[0010] 1 and 2, the inertial measurement unit 1 according to this embodiment includes a base substrate 2 having a plurality of lead terminals 3, an inertial sensor module 4 whose outer shape is molded from a first resin 9, a metal 5 disposed on the upper surface 4a of the inertial sensor module 4, components 6 such as a second inertial sensor 200, an oscillator 7, and a semiconductor element 50, and a second resin 8 that molds the base substrate 2, inertial sensor module 4, metal 5, and components 6. In other words, the outer shape of the inertial measurement unit 1 is molded from the second resin 8, and the inertial measurement unit 1 is configured as a resin package made of the second resin 8. The end of the lead terminal 3 opposite the base substrate 2 is exposed from the second resin 8.

[0011] The base substrate 2 is a flat plate, and the inertial sensor module 4, the second inertial sensor 200, and the oscillator 7 are arranged on the upper surface 2a, and the semiconductor element 50 and a plurality of lead terminals 3 extending from the outer edge of the base substrate 2 to the outside of the base substrate 2 are arranged on the lower surface 2b.

[0012] The inertial sensor module 4 will be described in detail with reference to FIGS. For ease of explanation, wiring that electrically connects the sensor elements 101, 102, 103, 301, 302, and 303 to the mounting terminals 42 formed on the lower surface 41a of the base substrate 41 is not shown in Figures 3 to 5. Furthermore, the first gyro sensor element 101, the second gyro sensor element 102, the third gyro sensor element 103, the first acceleration sensor element 301, the second acceleration sensor element 302, and the third acceleration sensor element 303 are illustrated in a simplified form in Figures 3 to 5.

[0013] 3 to 5, the inertial sensor module 4 includes a first inertial sensor 100, a third inertial sensor 300, a base substrate 41 on which the first inertial sensor 100 and the third inertial sensor 300 are arranged, and a first resin 9 that molds the first inertial sensor 100 and the third inertial sensor 300. That is, the outer shape of the inertial sensor module 4 is molded with the first resin 9, and the inertial sensor module 4 is configured as a resin package made of the first resin 9. In addition, a plurality of mounting terminals 42 are formed on a lower surface 41a of the base substrate 41.

[0014] The first inertial sensor 100 is a three-axis physical quantity sensor. The physical quantity is, for example, angular velocity, but may also be acceleration or another physical quantity. For example, if the physical quantity is angular velocity, the first inertial sensor 100 is a three-axis angular velocity sensor, and for example, if the physical quantity is acceleration, the first inertial sensor 100 is a three-axis acceleration sensor. The first inertial sensor 100 of this embodiment is a three-axis gyro sensor that includes a first gyro sensor element 101, a second gyro sensor element 102, and a third gyro sensor element 103, and is capable of measuring angular velocity about each of the detection axes, namely, the X-axis, which is the first axis, the Y-axis, which is the second axis, and the Z-axis, which is the third axis. The first gyro sensor element 101, the second gyro sensor element 102, and the third gyro sensor element 103 are gyro sensor elements manufactured by processing a silicon substrate using MEMS technology, and detect angular velocity based on a change in capacitance between a movable electrode and a fixed electrode.

[0015] 3 and 4, the first inertial sensor 100 has a substrate 10, a cover 10a, a first gyro sensor element 101, a second gyro sensor element 102, and a third gyro sensor element 103. The first gyro sensor element 101, the second gyro sensor element 102, and the third gyro sensor element 103 are housed in an internal space S1 defined by the substrate 10 and the cover 10a. The internal space S1 is an airtight space and is in a reduced pressure state, preferably closer to a vacuum.

[0016] In the first inertial sensor 100, the first gyro sensor element 101 detects an angular velocity around the X axis, the second gyro sensor element 102 detects an angular velocity around the Y axis, and the third gyro sensor element 103 detects an angular velocity around the Z axis.

[0017] The substrate 10 has three recesses 11, 12, and 13 formed therein that are recessed downward, and a first gyro sensor element 101, a second gyro sensor element 102, and a third gyro sensor element 103 are arranged on the substrate 10 so as to correspond to the recesses 11, 12, and 13, respectively. The recesses 11, 12, and 13 function as relief portions to prevent contact between the gyro sensor elements 101, 102, and 103 and the substrate 10, respectively.

[0018] The substrate 10 is mainly made of a glass material containing alkali metal ions, such as Pyrex (registered trademark) glass, which allows the gyro sensor elements 101, 102, and 103 formed from a silicon substrate to be firmly bonded to the substrate 10 by anodic bonding.

[0019] The lid body 10a has an upwardly recessed recess 11a formed therein, and when joined to the substrate 10, an internal space S1 is formed, which can accommodate the first gyro sensor element 101, the second gyro sensor element 102, and the third gyro sensor element 103. In this embodiment, the lid 10a is made of a silicon substrate, which allows the lid 10a and the substrate 10 to be firmly bonded together by anodic bonding.

[0020] The third inertial sensor 300 is a three-axis acceleration sensor that includes a first acceleration sensor element 301, a second acceleration sensor element 302, and a third acceleration sensor element 303, and is capable of measuring acceleration in each of the detection axes, namely, the X direction (first axis), the Y direction (second axis), and the Z direction (third axis). The first acceleration sensor element 301, the second acceleration sensor element 302, and the third acceleration sensor element 303 are acceleration sensor elements manufactured using MEMS technology, and detect acceleration based on changes in capacitance between a movable electrode and a fixed electrode.

[0021] 3 and 5, the third inertial sensor 300 includes a substrate 30, a cover 30a, a first acceleration sensor element 301, a second acceleration sensor element 302, and a third acceleration sensor element 303. The first acceleration sensor element 301, the second acceleration sensor element 302, and the third acceleration sensor element 303 are housed in an internal space S3 defined by the substrate 30 and the cover 30a. The internal space S3 is preferably an airtight space filled with an inert gas such as nitrogen, helium, or argon, and is preferably maintained at an operating temperature of approximately −40°C to 125°C and at approximately atmospheric pressure. However, the atmosphere in the internal space S3 is not particularly limited and may be, for example, reduced pressure or pressurized.

[0022] In the third inertial sensor 300, the first acceleration sensor element 301 detects acceleration in the X direction, the second acceleration sensor element 302 detects acceleration in the Y direction, and the third acceleration sensor element 303 detects acceleration in the Z direction.

[0023] The substrate 30 has three downwardly recessed portions 31, 32, and 33 formed therein, and the first acceleration sensor element 301, the second acceleration sensor element 302, and the third acceleration sensor element 303 are arranged on the substrate 30 so as to correspond to the recessed portions 31, 32, and 33, respectively. The recessed portions 31, 32, and 33 function as relief portions to prevent contact between the acceleration sensor elements 301, 302, and 303 and the substrate 30, respectively.

[0024] The substrate 30 is mainly made of a glass material containing alkali metal ions, such as Pyrex (registered trademark) glass, which allows the acceleration sensor elements 301, 302, and 303, each made of a silicon substrate, to be firmly bonded to the substrate 30 by anodic bonding.

[0025] The lid body 30a has an upwardly recessed recess 31a formed therein, and when joined to the substrate 30, an internal space S3 is formed, which can accommodate the first acceleration sensor element 301, the second acceleration sensor element 302, and the third acceleration sensor element 303. In this embodiment, the lid 30a is made of a silicon substrate, which allows the lid 30a and the substrate 30 to be firmly bonded together by anodic bonding.

[0026] Therefore, the inertial sensor module 4 is a six-axis combo sensor that includes a three-axis gyro sensor and a three-axis acceleration sensor.

[0027] In this embodiment, the inertial sensor module 4 is equipped with two sensors: the first inertial sensor 100, which is a three-axis gyro sensor, and the third inertial sensor 300, which is a three-axis acceleration sensor; however, this is not limited to this, and either the first inertial sensor 100 or the third inertial sensor 300 may be used.

[0028] 1 and 2, the metal 5 is a flat plate that is disposed on the upper surface 4a of the inertial sensor module 4 and is disposed so as to overlap and cover the upper surface 4a in a plan view. The metal 5 is also disposed between the first resin 9 and the second resin 8 of the inertial sensor module 4. Therefore, when the inertial sensor module 4 mounted on the base substrate 2 is resin-sealed with the second resin 8, it is possible to prevent moisture contained in the second resin 8 from penetrating into the first resin 9 of the inertial sensor module 4, thereby reducing the influence on the measurement of the inertial sensor module 4.

[0029] The second inertial sensor 200 will be described in detail with reference to FIGS. For ease of explanation, the lid 207 is not shown in Fig. 6. Furthermore, wiring electrically connecting the vibrating gyro sensor element 201 and the mounting terminals 205 formed on the base 202, and drive electrodes and detection electrodes formed on the vibrating gyro sensor element 201 are not shown in Figs. 6 and 7.

[0030] The second inertial sensor 200 is one of the components 6 and is a single-axis gyro sensor equipped with a vibration gyro sensor element 201, capable of measuring the angular velocity of the detection axis around the Z-axis, which serves as the third axis. The vibration gyro sensor element 201 is a gyro sensor element manufactured by processing a quartz substrate using photolithography technology, and converts the vibration of the detection vibration arm into an electrical signal to detect angular velocity. Furthermore, since the base material is quartz, it has excellent temperature characteristics. Therefore, compared to gyro sensor elements manufactured using MEMS technology, it is less susceptible to external noise and temperature effects, and has higher detection accuracy. In other words, the detection accuracy of the second inertial sensor 200 is higher than that of the first inertial sensor 100.

[0031] As shown in Figures 6 and 7, the second inertial sensor 200 has a vibration gyro sensor element 201, a base 202 made of ceramic or the like that houses the vibration gyro sensor element 201, and a lid 207 made of glass, ceramic, metal, or the like.

[0032] The base 202 is formed by laminating a plate-shaped first substrate 203 and a frame-shaped second substrate 204. The base 202 also has an internal space S2 that is open upward. The internal space S2 that houses the vibration gyro sensor element 201 is hermetically sealed in a reduced pressure state, preferably a state closer to a vacuum, by joining a lid 207 with a joining member 206 such as a seal ring.

[0033] A protrusion 21 that protrudes upward is formed on the upper surface 203a of the first substrate 203 of the base 202, and the vibrating gyro sensor element 201 is electrically and mechanically fixed to the upper surface 21a of the protrusion 21 via a metal bump 90 or the like. Therefore, contact between the vibrating gyro sensor element 201 and the first substrate 203 can be prevented.

[0034] A plurality of mounting terminals 205 are provided on the lower surface 203b of the first substrate 203 of the base 202. The mounting terminals 205 are electrically connected to the vibration gyro sensor element 201 via wiring (not shown).

[0035] The vibrating gyro sensor element 201 has a base 22 located in the center, a pair of detection vibrating arms 23 extending from the base 22 in the Y direction, a pair of connecting arms 24 extending from the base 22 in the X direction so as to be perpendicular to the detection vibrating arms 23, and pairs of drive vibrating arms 25, 26 extending in the Y direction from the tip side of each connecting arm 24 so as to be parallel to the detection vibrating arms 23. The vibrating gyro sensor element 201 is electrically and mechanically fixed at the base 22 to an upper surface 21a of a protrusion 21 provided on a base 202 via a metal bump 90 or the like.

[0036] When an angular velocity ωz about the Z axis is applied to the vibrating gyro sensor element 201 in a state where the drive vibrating arms 25, 26 are flexurally vibrating in the X direction in opposite phases to each other, a Coriolis force in the Y direction acts on the drive vibrating arms 25, 26 and the connecting arm 24, causing them to vibrate in the Y direction. This vibration causes the detection vibrating arm 23 to flexurally vibrate in the X direction. Therefore, the detection electrode formed on the detection vibrating arm 23 detects the distortion of the quartz crystal caused by the vibration as an electrical signal, thereby determining the angular velocity ωz.

[0037] In this embodiment, the second inertial sensor 200 is a uniaxial gyro sensor capable of measuring angular velocity around the Z-axis (the third axis). However, this is not a limitation, and a uniaxial gyro sensor capable of measuring angular velocity around the X-axis (the first axis) or the Y-axis (the second axis) may be used. The second inertial sensor 200 may also be a uniaxial acceleration sensor that has higher detection accuracy than the third inertial sensor 300 and is capable of measuring acceleration in the X-axis (the first axis), acceleration in the Y-axis (the second axis), or acceleration in the Z-axis (the third axis). The second inertial sensor 200 uses a sensor element based on quartz, but this is not a limitation, and any sensor may be used as long as it has higher detection accuracy than the first inertial sensor 100 or the third inertial sensor 300.

[0038] The oscillator 7 is one of the components 6, and as shown in Fig. 1, is disposed on the upper surface 2a of the base substrate 2. The oscillator 7 outputs a clock signal to the semiconductor element 50, and the semiconductor element 50 controls the detection timing and detection time of the angular velocity and acceleration detected by each of the sensors 100, 200, and 300 based on the clock signal.

[0039] The semiconductor element 50 is one of the components 6, and is disposed on the lower surface 2b of the base substrate 2, as shown in Fig. 2. The semiconductor element 50 includes a drive circuit that drives each of the sensors 100, 200, and 300, a detection circuit that detects angular velocities around three axes and accelerations in three axial directions based on signals from each of the sensors 100, 200, and 300, and an output circuit that converts signals from the detection circuits into predetermined signals and outputs them.

[0040] The second resin 8 molds the base substrate 2, the inertial sensor module 4, the metal 5, the components 6, and part of the lead terminals 3. In other words, the outer shape of the inertial measurement device 1 is molded from the second resin 8, and the inertial measurement device 1 is configured as a resin package made of the second resin 8.

[0041] As described above, in the inertial measurement unit 1 of this embodiment, the metal 5 is provided between the first resin 9 that constitutes the package of the inertial sensor module 4 and the second resin 8 that constitutes the package of the inertial measurement unit 1, so that when the inertial sensor module 4 mounted on the base substrate 2 is molded with the second resin 8, it is possible to prevent moisture contained in the second resin 8 from penetrating into the first resin 9 of the inertial sensor module 4, thereby reducing the influence on the measurement of the inertial sensor module 4. Therefore, it is possible to obtain an inertial measurement unit 1 with excellent detection accuracy.

[0042] Furthermore, the inertial measurement device 1 of this embodiment is equipped with a second inertial sensor 200 that has a detection axis around the Z axis, which is the third axis, and has a higher detection accuracy than the first inertial sensor 100, so an inertial measurement device 1 with even better detection accuracy can be obtained.

[0043] 2. Second embodiment Next, an inertial measurement device 1a according to a second embodiment will be described with reference to Figures 8 and 9. For ease of explanation, wiring electrically connecting the semiconductor element 50 formed on the base substrate 2 to the lead terminals 3, and wiring electrically connecting the semiconductor element 50 to the inertial sensor module 4 and each component 6 are not shown in Figures 8 and 9.

[0044] The inertial measurement unit 1a of this embodiment is similar to the inertial measurement unit 1 of the first embodiment, except that the shape of the metal 5a arranged on the top surface 4a of the inertial sensor module 4 is different from that of the inertial measurement unit 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment described above, and a description of similar points will be omitted.

[0045] 8 and 9, in the inertial measurement device 1a, metal 5a disposed on the top surface 4a of the inertial sensor module 4 covers the top surface 4a and four side surfaces 4b of the inertial sensor module 4. This prevents moisture from penetrating the second resin 8 not only from the top surface 4a of the inertial sensor module 4 but also from the four side surfaces 4b.

[0046] With this configuration, it is possible to obtain the same effects as the inertial measurement unit 1 of the first embodiment. [Explanation of symbols]

[0047] 1, 1a... inertial measurement unit, 2... base substrate, 2a... upper surface, 2b... lower surface, 3... lead terminal, 4... inertial sensor module, 4a... upper surface, 5... metal, 6... component, 7... oscillator, 8... second resin, 9... first resin, 10... substrate, 10a... lid, 11, 11a, 12, 13... recess, 21... convex portion, 21a... upper surface, 22... base, 23... detection vibrating arm, 24... connecting arm, 25... driving vibrating arm, 26... driving vibrating arm, 30... substrate, 30a... lid, 31, 31a, 32, 33... recess, 41... base substrate, 41a... lower surface, 42... mounting terminal, 50... semiconductor Conductor element, 90...metal bump, 100...first inertial sensor, 101...first gyro sensor element, 102...second gyro sensor element, 103...third gyro sensor element, 200...second inertial sensor, 201...vibration gyro sensor element, 202...base, 203...first substrate, 204...second substrate, 205...mounting terminal, 206...joint member, 207...lid, 300...third inertial sensor, 301...first acceleration sensor element, 302...second acceleration sensor element, 303...third acceleration sensor element, S1, S2, S3...internal space.

Claims

1. an inertial sensor module having a first inertial sensor and having an outer shape molded from a first resin; Components and a second resin for molding the inertial sensor module and the components; a metal that is a flat plate and is arranged so as to cover at least an upper surface of the inertial sensor module and is provided between the first resin and the second resin of the inertial sensor module; Inertial measurement unit.

2. the metal covers the top and side surfaces of the inertial sensor module; 10. The inertial measurement unit of claim 1.

3. the first inertial sensor has a first axis, a second axis, and a third axis, which are orthogonal to each other, as detection axes, respectively; 3. The inertial measurement device according to claim 1 or 2.

4. the component includes a second inertial sensor having a detection accuracy higher than that of the first inertial sensor and having the third axis as a detection axis; 4. The inertial measurement unit of claim 3.

5. the component includes a semiconductor element that controls the first inertial sensor; 5. An inertial measurement unit according to claim 1.

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