Patent Publication Number: US-2023147973-A1

Title: Inertial measurement unit

Description:
The present application is based on, and claims priority from JP Application Serial Number 2021-183112, filed Nov. 10, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an inertial measurement unit. 
     2. Related Art 
     An inertial measurement unit having an inertial sensor module having an inertial sensor such as an acceleration sensor or an angular velocity sensor is known. The inertial measurement unit is incorporated in various electronic devices or machines or is installed in a moving body such as a vehicle and is used to monitor an amount of inertia such as acceleration or angular velocity. 
     For example, JP-A-2017-49122 describes a sensor unit having a sensor device having an inertial sensor sealed with a sealing resin. 
     However, when moisture from outside enters the sealing resin as described above, the stress of the sealing resin may change. As the stress of the sealing resin changes, the inertial sensor is deformed, affecting the measurement by the sensor device. 
     SUMMARY 
     According to an aspect of the present disclosure, an inertial measurement unit includes: a substrate; a sealing member; a first inertial sensor module including a first inertial sensor and a first package accommodating the first inertial sensor; and a second inertial sensor module including a second inertial sensor and a second package accommodating the second inertial sensor. A material of the first package includes a resin. A material of the second package is an inorganic material. The first inertial sensor module is accommodated in a space between the substrate and the sealing member and thus airtightly sealed therein. The second inertial sensor module is provided outside the space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    schematically shows an inertial measurement unit according to a first embodiment. 
         FIG.  2    schematically shows a production process for the inertial measurement unit according to the first embodiment. 
         FIG.  3    schematically shows the production process for the inertial measurement unit according to the first embodiment. 
         FIG.  4    schematically shows an inertial measurement unit according to a modification example of the first embodiment. 
         FIG.  5    schematically shows an inertial measurement unit according to a second embodiment. 
         FIG.  6    schematically shows a production process for the inertial measurement unit according to the second embodiment. 
         FIG.  7    schematically shows the production process for the inertial measurement unit according to the second embodiment. 
         FIG.  8    schematically shows an inertial measurement unit according to a modification example of the second embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     A preferred embodiment of the present disclosure will now be described in detail, using the drawings. The embodiment described below should not unduly limit the content of the present disclosure described in the claims. Not all the configurations described below are necessarily essential configurations. 
     1. First Embodiment 
     1.1. Inertial Measurement Unit 
     First, an inertial measurement unit according to a first embodiment will be described with reference to the drawings.  FIG.  1    schematically shows an inertial measurement unit  100  according to the first embodiment. 
     The inertial measurement unit  100  has, for example, a substrate  10 , a terminal  16 , a cap  30 , a first inertial sensor module  40 , a second inertial sensor module  50 , a semiconductor element  60 , and an electronic component  62 , as shown in  FIG.  1   . 
     The substrate  10  has a first substrate  12  and a second substrate  14 . The first substrate  12  is, for example, a ceramic substrate of aluminum oxide or the like. The first substrate  12  may be formed of a plurality of ceramic layers stacked on each other or may be formed of a single ceramic layer. 
     The second substrate  14  is provided on the first substrate  12 . The second substrate  14  is provided between the first substrate  12  and the first inertial sensor module  40 . The second substrate  14  is joined to the first substrate  12 , for example, by a solder. As viewed from the direction of a perpendicular line P to the top surface of the first substrate  12 , the area of the second substrate  14  is smaller than the area of the first substrate  12 . The second substrate  14  has a plate-like member  15 . The plate-like member  15  is, for example, a ceramic substrate of aluminum oxide or the like. The plate-like member  15  may be formed of a plurality of ceramic layers stacked on each other or may be formed of a single ceramic layer. The second substrate  14  may have a recess. In this case, The second substrate  14  may be formed of a plurality of ceramic layers stacked on each other. 
     The terminal  16  is provided under the first substrate  12 . The terminal  16  protrudes from the first substrate  12 . The terminal  16  is provided in a plural number. The number of terminals  16  is not particularly limited. The material of the terminal  16  is, for example, a metal such as copper, aluminum, or gold. The inertial measurement unit  100  can be installed at an external member, not illustrated, via the terminal  16 . 
     The second substrate  14  has a terminal electrode  20 . The terminal electrode  20  penetrates the plate-like member  15  in the direction of the perpendicular line P. Specifically, a penetration hole is provided in the plate-like member  15  and the terminal electrode  20  is provided in the penetration hole. The terminal electrode  20  is provided in a plural number. The number of terminal electrodes  20  is not particularly limited. The material of the terminal electrode  20  is, for example, a metal such as silver, silver-palladium, platinum-silver, or copper. 
     The cap  30  is a sealing member described in the claims. The cap  30  is provided on the substrate  10 . In the illustrated example, the cap  30  is provided on the second substrate  14 . The cap  30  is joined to the second substrate  14 , for example, by a solder. The cap  30  is in the shape of a downwardly open case. The material of the cap  30  is, for example, a metal such as aluminum or stainless steel. The cap  30  is formed, for example, by press-molding a metal material. When the second substrate  14  has a recess, the cap  30  may be a flat plate. That is, the cap  30  may not have a recess. 
     The cap  30  together with the substrate  10  airtightly seals the first inertial sensor module  40 . In the illustrated example, the first inertial sensor module  40  is accommodated in a space  32  between the substrate  10  and the cap  30 . Specifically, the space  32  surrounded by the second substrate  14  and the cap  30  is airtightly sealed and the first inertial sensor module  40  is located in the space  32 . The cap  30  seals the first inertial sensor module  40  in the state where the airtightness of the space  32  is maintained. 
     The first inertial sensor module  40  is provided on the substrate  10 . In the illustrated example, the first inertial sensor module  40  is provided on the second substrate  14 . The first inertial sensor module  40  is joined to the second substrate  14 , for example, by a solder. The first inertial sensor module  40  is located inside the cap  30 . 
     The first inertial sensor module  40  has a first inertial sensor  42 . The first inertial sensor  42  may be an acceleration sensor detecting an acceleration or a gyro sensor detecting an angular velocity. The first inertial sensor module  40  may be a 6DoF (six-degrees of freedom) sensor. In this case, the first inertial sensor module  40  has a plurality of inertial sensors, not illustrated, in addition to the first inertial sensor  42 . Thus, the first inertial sensor module  40  can detect accelerations and angular velocities about three axes orthogonal to each other as detection axes. The first inertial sensor  42  is, for example, a silicon MEMS (micro-electromechanical systems) device. 
     The first inertial sensor module  40  has a first package  44 . The first package  44  accommodates the first inertial sensor  42 . The first package  44  molds the outer shape of the first inertial sensor module  40 . The material of the first package  44  includes a resin. Specifically, the material of the outside of the first package  44  is an epoxy resin. The inside of the resin of the first package  44  may be an inorganic material such as glass or silicon. 
     For example, two first inertial sensor modules  40  are provided. Averaging detection values detected by the two first inertial sensor modules  40  can make the detection accuracy of the inertial measurement unit  100  higher than when only one first inertial sensor module  40  is provided. The number of first inertial sensor modules  40  is not particularly limited and may be one, or three or more. 
     The second inertial sensor module  50  is provided on the substrate  10 . In the illustrated example, the second inertial sensor module  50  is provided on the first substrate  12 . The second inertial sensor module  50  is joined to the first substrate  12 , for example, by a solder. The second inertial sensor module  50  is located outside the cap  30 . The second inertial sensor module  50  is spaced apart from the second substrate  14 . 
     The second inertial sensor module  50  has a second inertial sensor  52 . The detection accuracy of the second inertial sensor  52  is, for example, higher than the detection accuracy of the first inertial sensor  42 . The second inertial sensor  52  is, for example, a quartz crystal gyro sensor. The second inertial sensor  52  may be an acceleration sensor. The second inertial sensor module  50  may also have a plurality of inertial sensors, not illustrated, in addition to the second inertial sensor  52 . 
     The second inertial sensor module  50  has a second package  54 . The second package  54  accommodates the second inertial sensor  52 . The second package  54  molds the outer shape of the second inertial sensor module  50 . The material of the outside of the second package  54  is not a resin. The material of the second package  54  is an inorganic material, which is less likely to be permeated by moisture than a resin. The material of the second package  54  is, for example, a ceramic or a metal. 
     The semiconductor element  60  is provided on the substrate  10 . In the illustrated example, the semiconductor element  60  is provided on the first substrate  12 . The semiconductor element  60  is joined to the first substrate  12 , for example, by a solder. The semiconductor element  60  is located outside the cap  30 . The semiconductor element  60  is spaced apart from the second substrate  14 . The semiconductor element  60  is formed, including an IC (integrated circuit). 
     The semiconductor element  60  drives the first inertial sensor  42 . The semiconductor element  60  is electrically coupled to the first inertial sensor  42 , for example, via a wiring, not illustrated, that is provided on the first substrate  12 , and via the terminal electrode  20 . The semiconductor element  60  is electrically coupled to the terminal  16 , for example, through a via hole, not illustrated, that penetrates the first substrate  12 . The semiconductor element  60  also drives the second inertial sensor  52 . The semiconductor element  60  is electrically coupled to the second inertial sensor  52 , for example, via a wiring, not illustrated, that is provided on the first substrate  12 . 
     The semiconductor element  60  may be not electrically coupled to the second inertial sensor  52 . In this case, the inertial measurement unit  100  includes a semiconductor element, not illustrated, that is electrically coupled to the second inertial sensor  52 . 
     The electronic component  62  is provided on the substrate  10 . In the illustrated example, the electronic component  62  is provided on the first substrate  12 . The electronic component  62  is joined to the first substrate  12 , for example, by a solder. The electronic component  62  is located outside the cap  30 . The number of electronic components  62  is not particularly limited. The electronic component  62  is electrically coupled to the terminal  16 , for example, through a via hole, not illustrated, that penetrates the first substrate  12 . The electronic component  62  is electrically coupled to the first inertial sensor  42 , for example, via a wiring, not illustrated, that is provided on the first substrate  12 . The electronic component  62  is, for example, a capacitor or the like. 
     1.2. Method for Producing Inertial Measurement Unit 
     A method for producing the inertial measurement unit  100  according to the first embodiment will now be described with reference to the drawings.  FIGS.  2  and  3    schematically show a production process for the inertial measurement unit  100  according to the first embodiment. 
     As shown in  FIG.  2   , the second substrate  14  provided with the terminal electrode  20 , the cap  30 , and the first inertial sensor module  40  are prepared. Next, the first inertial sensor module  40  is joined to the second substrate  14 . Next, the cap  30  is joined to the second substrate  14 , thus airtightly sealing the first inertial sensor module  40 . 
     As shown in  FIG.  3   , the first substrate  12  provided with the terminal  16 , the second inertial sensor module  50 , the semiconductor element  60 , and the electronic component  62  are prepared. Next, the second substrate  14  provided with the cap  30  and the first inertial sensor module  40 , the second inertial sensor module  50 , the semiconductor element  60 , and the electronic component  62  are jointed to the first substrate  12 . The order of joining the second substrate  14 , the second inertial sensor module  50 , the semiconductor element  60 , and the electronic component  62  is not particularly limited. 
     This process can produce the inertial measurement unit  100  as shown in  FIG.  1   . 
     1.3. Advantageous Effects 
     In the inertial measurement unit  100 , the first inertial sensor module  40  is accommodated in the space  32  between the substrate  10  and the cap  30  (sealing member) and thus airtightly sealed therein. The second inertial sensor module  50  is provided outside the space  32  between the substrate  10  and the cap  30  (sealing member). 
     Therefore, in the inertial measurement unit  100 , the probability of moisture entering the first package  44  whose material includes a resin can be made lower than when the first inertial sensor module is not airtightly sealed. Thus, in the inertial measurement unit  100 , the deformation of the first inertial sensor  42  due to the change in the stress of the first package  44  caused by the entry of moisture into the first package  44  can be restrained. Therefore, the first inertial sensor  42  can have good properties. 
     Also, in the inertial measurement unit  100 , the size of the cap  30  can be made smaller than when the second inertial sensor module is provided inside the cap. Thus, a reduction in cost can be achieved in the inertial measurement unit  100 . 
     In the inertial measurement unit  100 , the substrate  10  has the first substrate  12 , and the second substrate  14  arranged between the first inertial sensor module  40  and the first substrate  12 . The first inertial sensor module  40  is accommodated in the space  32  between the second substrate  14  and the cap  30  (sealing member). The second inertial sensor module  50  is provided on the first substrate  12  and spaced apart from the second substrate  14 . Therefore, in the inertial measurement unit  100 , the second substrate  14  and the cap  30  together can easily airtightly seal the first inertial sensor module  40 . For example, when the second substrate is not provided and the first substrate and the cap together airtightly seal the first inertial sensor module, a wiring, not illustrated, that is electrically coupled to the first inertial sensor needs to be laid between the first substrate and the cap, making the airtight sealing difficult. Also, in the inertial measurement unit  100 , the size of the second substrate  14  can be made smaller than when the second inertial sensor module is provided at the second substrate. Thus, a reduction in cost can be achieved. 
     The inertial measurement unit  100  has the semiconductor element  60  driving the first inertial sensor  42 . The second substrate  14  has the plate-like member  15  and the terminal electrode  20  penetrating the plate-like member  15 . The semiconductor element  60  is electrically coupled to the first inertial sensor  42  via the terminal electrode  20 . Therefore, in the inertial measurement unit  100 , the semiconductor element  60  and the first inertial sensor  42  can be electrically coupled together while the first inertial sensor module  40  is airtightly sealed. 
     In the inertial measurement unit  100 , the material of the second package  54  is a ceramic. Therefore, in the inertial measurement unit  100 , the entry of moisture into the second inertial sensor  52  can be restrained. 
     In the inertial measurement unit  100 , the first inertial sensor module  40  uses three axes orthogonal to each other as detection axes. Therefore, the inertial measurement unit  100  can detect an amount of inertia, using the three axes orthogonal to each other as the detection axes. 
     In the inertial measurement unit  100 , the first inertial sensor module  40  detects an acceleration and an angular velocity. Therefore, the inertial measurement unit  100  can detect an acceleration and an angular velocity, using the three axes orthogonal to each other as the detection axes. 
     In the inertial measurement unit  100 , the detection accuracy of the second inertial sensor  52  is higher than the detection accuracy of the first inertial sensor  42 . Therefore, the inertial measurement unit  100  can detect an amount of inertia with high accuracy by the second inertial sensor  52 . 
     1.4. Modification Example 
     An inertial measurement unit according to a modification example of the first embodiment will now be described with reference to the drawings.  FIG.  4    schematically shows an inertial measurement unit  110  according to a modification example of the first embodiment. In the following description of the inertial measurement unit  110  according to the modification example of the first embodiment, components having functions similar to those of components of the inertial measurement unit  100  are denoted by the same reference signs and are not described further in detail. 
     The inertial measurement unit  110  differs from the inertial measurement unit  100  in having a mold resin  70 , as shown in  FIG.  4   . 
     The mold resin  70  covers the first substrate  12 , the second substrate  14 , the cap  30 , the second inertial sensor module  50 , the semiconductor element  60 , and the electronic component  62 . In the illustrated example, the mold resin  70  covers the side surface and the bottom surface of the first substrate  12 . The terminal  16  protrudes from the mold resin  70 . The material of the mold resin  70  is, for example, an epoxy resin. The mold resin  70  is formed, for example, by a method such as spin coating or CVD (chemical vapor deposition). 
     The inertial measurement unit  110  has the mold resin  70  covering the cap  30  and the second inertial sensor module  50 . Therefore, in the inertial measurement unit  110 , an external impact on the cap  30  and the second inertial sensor module  50  can be reduced. Thus, the breakage or falling-off of the cap  30  and the second inertial sensor module  50  can be restrained. The external impact may be contact with an external member, not illustrated, or the like. 
     2. Second Embodiment 
     2.1. Inertial Measurement Unit 
     An inertial measurement unit according to a second embodiment will now be described with reference to the drawings.  FIG.  5    schematically shows an inertial measurement unit  200  according to the second embodiment. In the following description of the inertial measurement unit  200  according to the second embodiment, components having functions similar to those of components of the inertial measurement units  100 ,  110  are denoted by the same reference signs and are not described further in detail. 
     In the inertial measurement unit  100 , the second substrate  14  and the cap  30  airtightly seal the first inertial sensor module  40 , as shown in  FIG.  1   . 
     In contrast, in the inertial measurement unit  200 , the cap  30  is not provided and the first inertial sensor module  40  is accommodated in the space  32  between a recess  18  on the substrate  12  and a third substrate  14  and thus airtightly sealed therein, as shown in  FIG.  5   . The third substrate  14  is a sealing member in the claims. 
     The recess  18  is provided on the substrate  12 . The recess  18  is provided at the top surface of the substrate  12 . In the illustrated example, the substrate  12  is formed of five ceramic layers  2 . A part of the third, fourth, and the fifth ceramic layers  2  from the bottom, of the five ceramic layers  2 , are eliminated to form the recess  18 . The ceramic layer  2  is, for example, an aluminum oxide layer. The number of ceramic layers  2  is not particularly limited. 
     The third substrate  14  closes the recess  18 . The space  32 , where the recess  18  is provided, is airtightly sealed by the substrate  12  and the third substrate  14 . The third substrate  14  has a first surface  14   a  and a second surface  14   b  facing the opposite directions. The third substrate  14  is joined to the substrate  12 , with the first surface  14   a  facing the substrate  12 . In the illustrated example, the third substrate  14  is formed of three ceramic layers  4 . The ceramic layer  4  is, for example, an aluminum oxide layer. The number of ceramic layers  4  is not particularly limited. 
     The first inertial sensor module  40  is provided on the first surface  14   a  of the third substrate  14 . In the illustrated example, only one first inertial sensor module  40  is provided. The first inertial sensor module  40  is located in the space  32 . In the illustrated example, four electronic components  62  are provided. Two electronic components  62 , of the four electronic components  62 , are provided on the first surface  14   a  of the third substrate  14  and located in the space  32 . The other two electronic components  62  are provided on the substrate  12  and not located in the space  32 . 
     The semiconductor element  60  is provided on the second surface  14   b  of the third substrate  14 . The semiconductor element  60  is not located in the recess  18 . Although not illustrated, the semiconductor element  60  may be provided on the substrate  12 . 
     2.2. Method for Producing Inertial Measurement Unit 
     A method for producing the inertial measurement unit  200  according to the second embodiment will now be described with reference to the drawings.  FIGS.  6  and  7    schematically show a production process for the inertial measurement unit  200  according to the second embodiment. 
     As shown in  FIG.  6   , the third substrate  14  provided with the terminal electrode  20 , the first inertial sensor module  40 , and the electronic component  62  are prepared. Next, the first inertial sensor module  40  and the electronic component  62  are joined to the first surface  14   a  of the third substrate  14 . Next, the semiconductor element  60  is joined to the second surface  14   b  of the third substrate  14 . The order of joining the second inertial sensor module  50 , the semiconductor element  60 , and the electronic component  62  is not particularly limited. 
     As shown in  FIG.  7   , the first substrate  12  provided with the recess  18 , the second inertial sensor module  50 , the semiconductor element  60 , and the electronic component  62  are prepared. Next, the third substrate  14  provided with the first inertial sensor module  40  and the electronic component  62 , the second inertial sensor module  50 , the semiconductor element  60 , and the electronic component  62  are jointed to the substrate  12 . The third substrate  14  is joined to the substrate  12 , with the first surface  14   a  facing the substrate  12 , thus airtightly sealing the recess  18 . The order of joining the third substrate  14 , the second inertial sensor module  50 , the semiconductor element  60 , and the electronic component  62  is not particularly limited. 
     This process can produce the inertial measurement unit  200  as shown in  FIG.  5   . 
     2.3. Advantageous Effects 
     In the inertial measurement unit  200 , the first inertial sensor module  40  is accommodated in the space  32  between the recess  18  in the substrate  12  and the third substrate  14  and thus airtightly sealed therein. 
     Therefore, in the inertial measurement unit  200 , as in the inertial measurement unit  100 , the probability of moisture entering the first package  44  whose material includes a resin can be reduced. Also, in the inertial measurement unit  200 , the size of the third substrate  14  can be made smaller than when the second inertial sensor module is provided in the space between the recess in the substrate and the third substrate. Thus, a reduction in cost can be achieved in the inertial measurement unit  200 . 
     2.4. Modification Example 
     An inertial measurement unit according to a modification example of the second embodiment will now be described with reference to the drawings.  FIG.  8    schematically shows an inertial measurement unit  210  according to a modification example of the second embodiment. In the following description of the inertial measurement unit  210  according to the modification example of the second embodiment, components having functions similar to those of components of the inertial measurement units  100 ,  110 ,  200  are denoted by the same reference signs and are not described further in detail. 
     The inertial measurement unit  210  differs from the inertial measurement unit  200  in having the mold resin  70 , as shown in  FIG.  8   . 
     In the inertial measurement unit  210 , the mold resin  70  covers the substrate  12 , the third substrate  14 , the terminal electrode  20 , the second inertial sensor module  50 , the semiconductor element  60 , and the electronic component  62 . 
     The inertial measurement unit  210  has the mold resin  70  covering the substrate  12 , the third substrate  14 , and the second inertial sensor module  50 , as described above. Therefore, in the inertial measurement unit  210 , an external impact on the substrate  12 , the third substrate  14 , and the second inertial sensor module  50  can be reduced, as in the inertial measurement unit  110 . 
     The above embodiments and modification examples are simply examples. The present disclosure is not limited to these embodiments and modification examples. For example, the embodiments and the modification examples can be suitably combined together where appropriate. 
     The present disclosure includes a configuration that is substantially the same as any of the configurations described in the embodiments, for example, a configuration having the same function, method, and result, or a configuration having the same object and effect. The present disclosure also includes a configuration formed by replacing a non-essential part of any of the configurations described in the embodiments. The present disclosure also includes a configuration having the same advantageous effect as any of the configurations described in the embodiments or a configuration that can achieve the same object. The present disclosure also includes a configuration formed by adding a known technique to any of the configurations described in the embodiments. 
     The following contents are derived from the above embodiments and modification examples. 
     According to an aspect, the inertial measurement unit includes: a substrate; a sealing member; a first inertial sensor module including a first inertial sensor and a first package accommodating the first inertial sensor; and a second inertial sensor module including a second inertial sensor and a second package accommodating the second inertial sensor. A material of the first package includes a resin. A material of the second package is an inorganic material. The first inertial sensor module is accommodated in a space between the substrate and the sealing member and thus airtightly sealed therein. The second inertial sensor module is provided outside the space. 
     According to another aspect, the inertial measurement unit includes: a substrate; a sealing member; a first inertial sensor module including a first inertial sensor and a first package accommodating the first inertial sensor; and a second inertial sensor module including a second inertial sensor and a second package accommodating the second inertial sensor. A material of the first package includes a resin. A material of the second package is not a resin. The first inertial sensor module is accommodated in a space between the substrate and the sealing member and thus airtightly sealed therein. The second inertial sensor module is provided outside the space between the substrate and the sealing member. 
     In this inertial measurement unit, the probability of moisture entering the first package whose material includes a resin can be reduced. 
     According to another aspect, in the inertial measurement unit, the substrate may have a first substrate, and a second substrate arranged between the first inertial sensor module and the first substrate. The sealing member may be a cap. The first inertial sensor module may be accommodated in the space between the second substrate and the cap. The second inertial sensor module may be provided at the first substrate and spaced apart from the second substrate. 
     In this inertial measurement unit, the second substrate and the sealing member together can easily airtightly seal the first inertial sensor module. 
     According to another aspect, the inertial measurement unit may have a mold resin covering the cap and the second inertial sensor module. 
     In this inertial measurement unit, an external impact on the cap and the second inertial sensor module can be reduced. 
     According to another aspect, the inertial measurement unit may have a semiconductor element driving the first inertial sensor. The second substrate may have a plate-like member, and a terminal electrode penetrating the plate-like member. The semiconductor element may be electrically coupled to the first inertial sensor via the terminal electrode. 
     In this inertial measurement unit, the semiconductor element and the first inertial sensor can be electrically coupled together while the first inertial sensor module is airtightly sealed. 
     According to another aspect, in the inertial measurement unit, the substrate may be provided with a recess. The sealing member may be a third substrate. The first inertial sensor module may be accommodated in the space between the recess in the substrate and the third substrate and thus airtightly sealed therein. 
     In this inertial measurement unit, the probability of moisture entering the first package whose material includes a resin can be reduced. 
     According to another aspect, the inertial measurement unit may have a mold resin covering the substrate, the third substrate, and the second inertial sensor module. 
     In this inertial measurement unit, an external impact on the substrate, the third substrate, and the second inertial sensor module can be reduced. 
     According to another aspect, the inertial measurement unit may have a semiconductor element driving the first inertial sensor. The third substrate may have a plate-like member, and a terminal electrode penetrating the plate-like member. The semiconductor element may be electrically coupled to the first inertial sensor via the terminal electrode. 
     In this inertial measurement unit, the semiconductor element and the first inertial sensor can be electrically coupled together while the first inertial sensor module is airtightly sealed. 
     According to another aspect, in the inertial measurement unit, the material of the second package may be a ceramic. 
     In this inertial measurement unit, the entry of moisture into the second inertial sensor can be restrained. 
     According to another aspect, in the inertial measurement unit, the first inertial sensor module may use three axes orthogonal to each other as detection axes. 
     In this inertial measurement unit, an amount of inertia can be detected using the three axes orthogonal to each other as the detection axes. 
     According to another aspect, in the inertial measurement unit, the first inertial sensor module may detect an acceleration and an angular velocity. 
     In this inertial measurement unit, an acceleration and an angular velocity can be detected using the three axes orthogonal to each other as the detection axes. 
     According to another aspect, in the inertial measurement unit, a detection accuracy of the second inertial sensor may be higher than a detection accuracy of the first inertial sensor. 
     In this inertial measurement unit, an amount of inertia can be detected with high accuracy by the second inertial sensor.