Patent Publication Number: US-2022229085-A1

Title: Sensor module

Description:
The present application is based on, and claims priority from JP Application Serial Number 2021-007141, filed Jan. 20, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a sensor module. 
     2. Related Art 
     In the related art, as described in JP-A-2004-31787, an electronic device is known in which a projecting piece provided at a hem portion of a metal cap and an insulating substrate surface are coupled by soldering or the like to dispose the metal cap so as to cover an electronic component mounted on an insulating substrate such as a printed circuit board. 
     In the electronic device described in JP-A-2004-31787, two opposing projecting pieces projecting from a central portion of the hem portions of the metal cap are coupled to the insulating substrate, and thus, in a step of mounting the electronic device or a thermal cycle in working environment of the electronic device, a stress caused by a difference in thermal expansion coefficient between the metal cap and the insulating substrate is applied to the insulating substrate. Since this stress is strongly applied to the insulating substrate in a linear region connecting the two opposing projecting pieces of the metal cap, when an electronic component such as a piezoelectric vibrator mounted on the insulating substrate is disposed in the linear region connecting two opposing projecting pieces of the metal cap, the stress is also applied to the electronic component, and characteristics of the electronic component change. 
     Such a change in the characteristics of the electronic component is the same as that of an electronic component other than an oscillator, for example, a sensor using vibration of an inertial element formed from a piezoelectric substrate such as crystal or a semiconductor substrate such as silicon using micro electro mechanical systems (MEMS) technology. In such a sensor, when the stress is applied to the sensor, the characteristics of the sensor may change and the detection accuracy of the sensor may decrease. 
     SUMMARY 
     A sensor module includes: a rectangular printed circuit board that has a main surface, a first recessed portion formed at a first side of the main surface, a second recessed portion formed at a second side facing the first side, a third recessed portion formed at a third side adjacent to the first side and the second side, and a fourth recessed portion formed at a fourth side facing the third side; a metal cap that includes a first convex portion bonded to the first recessed portion of the printed circuit board, a second convex portion bonded to the second recessed portion, a third convex portion bonded to the third recessed portion, and a fourth convex portion bonded to the fourth recessed portion; a first inertial sensor that is provided at the main surface of the printed circuit board and that is accommodated between the main surface and the metal cap; and a second inertial sensor that is provided at the main surface of the printed circuit board and that is accommodated between the main surface and the metal cap. In a plan view from a direction orthogonal to the main surface of the printed circuit board, the first inertial sensor and the second inertial sensor are disposed outside a region surrounded by a line segment connecting both ends of the first recessed portion of the printed circuit board in a width direction and both ends of the second recessed portion of the printed circuit board in the width direction, and outside a region surrounded by a line segment connecting both ends of the third recessed portion in the width direction and both ends of the fourth recessed portion in the width direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a sensor module according to a first embodiment. 
         FIG. 2  is a bottom view of the sensor module according to the first embodiment. 
         FIG. 3  is a cross-sectional view taken along a line A-A in  FIG. 1 . 
         FIG. 4  is a plan view illustrating a portion E in  FIG. 1 . 
         FIG. 5  is a plan view illustrating a portion F in  FIG. 1 . 
         FIG. 6  is a plan view of a sensor module according to a second embodiment. 
         FIG. 7  is a plan view illustrating a portion G in  FIG. 6 . 
         FIG. 8  is a plan view illustrating a portion H in  FIG. 6 . 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     1. First Embodiment 
     A sensor module  1  according to a first embodiment will be described with reference to  FIGS. 1 to 5 .  FIG. 1  illustrates an internal configuration of the sensor module  1  in a state in which a top plate portion  70  of a metal cap  7  is removed for convenience of description.  FIGS. 4 and 5  illustrate internal configurations of a first inertial sensor  3  and a second inertial sensor  4 , in which components other than an acceleration sensor element, an angular velocity sensor element, and an internal electrode are omitted for convenience of description. The dimensional ratio of components in the drawings is different from the actual dimensional ratio. 
     In the coordinates illustrated in the drawings, three axes orthogonal to one another are referred to as an X axis, a Y axis, and a Z axis. A direction along the X axis is defined as an “X direction”, a direction along the Y axis is defined as a “Y direction”, a direction along the Z axis is defined as a “Z direction”, and a direction of an arrow is a plus direction. A plus direction in the Z direction is referred to as “upper” or “upward”, and a minus direction in the Z direction is referred to as “lower” or “downward”. In a plan view from the Z direction, a surface on a plus side in the Z direction is referred to as an upper surface, and a surface on a minus side in the Z direction, which is an opposite-side surface from the upper surface, is referred to as a lower surface. 
     As illustrated in  FIGS. 1 to 3 , the sensor module  1  includes a printed circuit board  2 , a metal cap  7  bonded to a main surface  21  which is an upper surface of the printed circuit board  2 , a first inertial sensor  3 , a second inertial sensor  4 , and an angular velocity sensor  5  that are provided at the main surface  21  of the printed circuit board  2  and that are accommodated between the main surface  21  and the metal cap  7 , a semiconductor device  8  mounted at a lower surface  22  of the printed circuit board  2 , and a lead group  90  including a plurality of lead terminals  9  electrically coupled to the lower surface  22  of the printed circuit board  2 . 
     The printed circuit board  2  has, in a plan view from the Z direction orthogonal to the main surface  21  of the printed circuit board  2 , a plate shape having a rectangular outer shape. As the printed circuit board  2 , for example, a ceramic substrate, a glass epoxy substrate, or the like can be used. For convenience of illustration, a wiring formed at the printed circuit board  2  is not illustrated, and only an external coupling terminal  292  disposed at the lower surface  22  is illustrated. 
     The printed circuit board  2  has, in the plan view from the Z direction, a first side  2 A, a second side  2 B facing the first side  2 A, a third side  2 C adjacent to the first side  2 A and the second side  2 B, and a fourth side  2 D facing the third side  2 C. 
     The term “rectangle” is a concept including a square and a rectangle, and further including a shape having a non-rectangular portion different from the rectangle in a part of the rectangle. The non-rectangular portion is, for example, a portion in which a corner of a rectangle is chamfered in a curved shape or a linear shape, a convex portion in which a part of a side surrounding the rectangle protrudes to the outside of the rectangle, a recessed portion such as a notch recessed to the inside of the rectangle, or the like. Accordingly, each side constituting the rectangle may be divided by the non-rectangular portion. 
     “Adjacent to” is a concept including not only a case in which two sides intersecting each other among the sides constituting the rectangle are in direct contact with each other, but also a case in which the two sides are in indirect contact with each other via the non-rectangular portion. For example, a case that the first side  2 A and the third side  2 C are adjacent to each other is not limited to a case in which the first side  2 A and the third side  2 C are in contact with each other at the corners of the rectangle, and may be in contact with each other via the non-rectangular portion such as a portion where the corners of the rectangle are chamfered. 
     In the main surface  21  of the printed circuit board  2 , a first recessed portion  23 A is formed at the first side  2 A, a second recessed portion  23 B is formed at the second side  2 B, a third recessed portion  23 C is formed at the third side  2 C, and a fourth recessed portion  23 D is formed at the fourth side  2 D. In the present embodiment, the recessed portions  23 A,  23 B,  23 C, and  23 D are respectively formed in central portions of the sides  2 A,  2 B,  2 C, and  2 D, but may be formed in portions other than the central portions of the sides  2 A,  2 B,  2 C, and  2 D. 
     Next, each portion located at a main surface  21  side of the printed circuit board  2  will be described. 
     As illustrated in  FIGS. 1 and 3 , the metal cap  7  is bonded to the main surface  21  of the printed circuit board  2 . The first inertial sensor  3 , the second inertial sensor  4 , and the angular velocity sensor  5  are provided at the main surface  21  of the printed circuit board  2 . The metal cap  7  is bonded to the main surface  21  of the printed circuit board  2 , so that the first inertial sensor  3 , the second inertial sensor  4 , and the angular velocity sensor  5  are accommodated between the main surface  21  of the printed circuit board  2  and the metal cap  7 . 
     The metal cap  7  has, in the plan view from the Z direction, a rectangular shape substantially similar to the printed circuit board  2 . As the metal cap  7 , for example, a  42  alloy, which is an iron-nickel alloy, can be used. 
     The metal cap  7  includes the top plate portion  70 , a side wall  71  extending downward from an outer peripheral edge of the top plate portion  70 , a recessed portion  711  formed by the top plate portion  70  and the side wall  71 , and a first convex portion  72 A, a second convex portion  72 B, a third convex portion  72 C, and a fourth convex portion  72 D that protrude inward from a lower end portion of the side wall  71 . 
     The metal cap  7  is disposed at the main surface  21  of the printed circuit board  2  so as to accommodate the first inertial sensor  3 , the second inertial sensor  4 , and the angular velocity sensor  5  in the recessed portion  711 . 
     In the plan view from the Z direction, the convex portions  72 A,  72 B,  72 C, and  72 D of the metal cap  7  respectively overlap the recessed portions  23 A,  23 B,  23 C, and  23 D of the printed circuit board  2 . 
     The first convex portion  72 A of the metal cap  7  is bonded to the first recessed portion  23 A of the printed circuit board  2  via an adhesive member  74 . Similarly, the second convex portion  72 B of the metal cap  7  is bonded to the second recessed portion  23 B of the printed circuit board  2  via the adhesive member  74 , the third convex portion  72 C is bonded to the third recessed portion  23 C via the adhesive member  74 , and the fourth convex portion  72 D is bonded to the fourth recessed portion  23 D via the adhesive member  74 . 
     As the adhesive member  74 , a resin adhesive made of an epoxy resin, a urethane resin, a silicone resin, or the like can be used. The adhesive member  74  may have electrical conductivity. As the adhesive member  74 , for example, solder or the like may be used in addition to the resin adhesive. 
     The first inertial sensor  3  and the second inertial sensor  4  are so-called six-axis inertial sensors that detect angular velocities around three axes which are the X axis, the Y axis, and the Z axis and accelerations in the directions along the three axes. 
     The angular velocity sensor  5  is provided to accurately detect a desired angular velocity around a detection axis among the three axes which are the X axis, the Y axis, and the Z axis. In the present embodiment, the angular velocity sensor  5  detects an angular velocity around the Z axis. The angular velocity sensor  5  may be omitted. 
     Here, a disposition of the first inertial sensor  3  and the second inertial sensor  4  according to the present embodiment will be described. 
     As illustrated in  FIG. 1 , in the plan view from the Z direction orthogonal to the main surface  21  of the printed circuit board  2 , the first inertial sensor  3  and the second inertial sensor  4  are disposed outside a region  243  surrounded by a line segment L 1  connecting both ends of the first recessed portion  23 A of the printed circuit board  2  in a width direction and both ends of the second recessed portion  23 B of the printed circuit board  2  in the width direction, and outside a region  244  surrounded by a line segment L 2  connecting both ends of the third recessed portion  23 C of the printed circuit board  2  in the width direction and both ends of the fourth recessed portion  23 D of the printed circuit board  2  in the width direction. 
     The line segment L 1  connecting both ends of the first recessed portion  23 A of the printed circuit board  2  in the width direction and both ends of the second recessed portion  23 B of the printed circuit board  2  in the width direction includes, in the plan view from the Z direction, a first line segment L 11  connecting end portions on the plus side in the Y direction of the first recessed portion  23 A and the second recessed portion  23 B in the width direction, and a second line segment L 12  connecting end portions on the minus side in the Y direction of the first recessed portion  23 A and the second recessed portion  23 B in the width direction. The first line segment L 11  and the second line segment L 12  do not intersect with each other. 
     Specifically, in the plan view from the Z direction, the region  243  surrounded by the line segment L 1  connecting both ends of the first recessed portion  23 A of the printed circuit board  2  in the width direction and both ends of the second recessed portion  23 B of the printed circuit board  2  in the width direction is a region surrounded by the first line segment L 11 , the second line segment L 12 , an outer edge of the first recessed portion  23 A in the width direction, and an outer edge of the second recessed portion  23 B in the width direction. 
     The line segment L 2  connecting both ends of the third recessed portion  23 C of the printed circuit board  2  in the width direction and both ends of the fourth recessed portion  23 D of the printed circuit board  2  in the width direction includes, in the plan view from the Z direction, a third line segment L 21  connecting the ends on the plus side in the X direction of the third recessed portion  23 C and the fourth recessed portion  23 D in the width direction, and a fourth line segment L 22  connecting the ends on the minus side in the X direction of the third recessed portion  23 C and the fourth recessed portion  23 D in the width direction. The third line segment L 21  and the fourth line segment L 22  do not intersect with each other. 
     Specifically, the region  244  surrounded by the line segment L 2  connecting both ends of the third recessed portion  23 C of the printed circuit board  2  in the width direction and both ends of the fourth recessed portion  23 D of the printed circuit board  2  in the width direction is a region surrounded by the third line segment L 21 , the fourth line segment L 22 , an outer edge of the third recessed portion  23 C in the width direction, and an outer edge of the fourth recessed portion  23 D in the width direction. 
     The region  243  surrounded by the line segment L 1  connecting both ends of the first recessed portion  23 A of the printed circuit board  2  in the width direction and both ends of the second recessed portion  23 B of the printed circuit board  2  in the width direction extends along the X direction in the plan view from the Z direction. The region  244  surrounded by the line segment L 2  connecting both ends of the third recessed portion  23 C of the printed circuit board  2  in the width direction and both ends of the fourth recessed portion  23 D of the printed circuit board  2  in the width direction extends along the Y direction in the plan view from the Z direction. 
     The region  243  surrounded by the line segment L 1  connecting both ends of the first recessed portion  23 A of the printed circuit board  2  in the width direction and both ends of the second recessed portion  23 B of the printed circuit board  2  in the width direction, and the region  244  surrounded by the line segment L 2  connecting both ends of the third recessed portion  23 C of the printed circuit board  2  in the width direction and both ends of the fourth recessed portion  23 D of the printed circuit board  2  in the width direction intersect with each other at a central portion of the printed circuit board  2 . A shape, in which the region  243  surrounded by the line segment L 1  connecting both ends of the first recessed portion  23 A in the width direction and both ends of the second recessed portion  23 B in the width direction and the region  244  surrounded by the line segment L 2  connecting both ends of the third recessed portion  23 C in the width direction and both ends of the fourth recessed portion  23 D in the width direction are superposed, is a cross shape. 
     In the present embodiment, as described above, the main surface  21  of the printed circuit board  2  is divided into a cross shape by the region  243  surrounded by the line segment L 1  and the region  244  surrounded by the line segment L 2 . The main surface  21  of the printed circuit board  2  includes the region  243  surrounded by the line segment L 1 , the region  244  surrounded by the line segment L 2 , and a first mounting region  246 , a second mounting region  247 , a third mounting region  248 , and a fourth mounting region  249  that are divided by the region  243  and the region  244 . In the plan view from the Z direction, the first mounting region  246 , the second mounting region  247 , the third mounting region  248 , and the fourth mounting region  249  are regions outside the region  243  surrounded by the line segment L 1  and the region  244  surrounded by the line segment L 2 . 
     Specifically, in the plan view from the Z direction, the first mounting region  246  is a region on the plus side in the Y direction with respect to the first line segment L 11  and on the plus side in the X direction with respect to the third line segment L 21 . Similarly, the second mounting region  247  is a region on the plus side in the Y direction with respect to the first line segment L 11  and on the minus side in the X direction with respect to the fourth line segment L 22 , the third mounting region  248  is a region on the minus side in the Y direction with respect to the second line segment L 12  and on the minus side in the X direction with respect to the fourth line segment L 22 , and the fourth mounting region  249  is a region on the minus side in the Y direction with respect to the second line segment L 12  and on the plus side in the X direction with respect to the third line segment L 21 . 
     The region  243  surrounded by the line segment L 1  connecting both ends of the first recessed portion  23 A of the printed circuit board  2  in the width direction and both ends of the second recessed portion  23 B of the printed circuit board  2  in the width direction, and the region  244  surrounded by the line segment L 2  connecting both ends of the third recessed portion  23 C of the printed circuit board  2  in the width direction and both ends of the fourth recessed portion  23 D of the printed circuit board  2  in the width direction are regions in which stress due to a difference in thermal expansion coefficient between the metal cap  7  and the printed circuit board  2  is strongly applied to the printed circuit board  2 . 
     The first mounting region  246 , the second mounting region  247 , the third mounting region  248 , and the fourth mounting region  249  are regions in which the stress due to the difference in thermal expansion coefficient between the metal cap  7  and the printed circuit board  2  is less likely to be applied to the printed circuit board  2 . That is, the first mounting region  246 , the second mounting region  247 , the third mounting region  248 , and the fourth mounting region  249  are regions suitable for disposing the first inertial sensor  3  and the second inertial sensor  4  on the main surface  21  of the printed circuit board  2 . 
     In the present embodiment, the first inertial sensor  3  is disposed in the first mounting region  246 , and the second inertial sensor  4  is disposed in the third mounting region  248 . However, the disposition of the first inertial sensor  3  and the second inertial sensor  4  is not limited thereto, and the first inertial sensor  3  and the second inertial sensor  4  may be disposed in any of the first mounting region  246 , the second mounting region  247 , the third mounting region  248 , and the fourth mounting region  249 . 
     As described above, in the plan view from the Z direction, the first inertial sensor  3  and the second inertial sensor  4  are disposed in the mounting regions  246 ,  247 ,  248 , and  249  outside the region  243  surrounded by the line segment L 1  connecting both ends of the first recessed portion  23 A of the printed circuit board  2  in the width direction and both ends of the second recessed portion  23 B of the printed circuit board  2  in the width direction and the region  244  surrounded by the line segment L 2  connecting both ends of the third recessed portion  23 C in the width direction and both ends of the fourth recessed portion  23 D in the width direction, so that the stress caused by the difference in thermal expansion coefficient between the metal cap  7  and the printed circuit board  2  is less likely to be applied to the first inertial sensor  3  and the second inertial sensor  4 . Accordingly, even if working environment or the like of the sensor module  1  changes, detection accuracy of the first inertial sensor  3  and the second inertial sensor  4  is less likely to decrease, and the sensor module  1  having high accuracy can be implemented. 
     Next, basic configurations of the first inertial sensor  3  and the second inertial sensor  4  will be described. 
     As illustrated in  FIGS. 4 and 5 , the first inertial sensor  3  and the second inertial sensor  4  have a similar basic configuration, and in the plan view from the Z direction, the second inertial sensor  4  is mounted in a posture in which the first inertial sensor  3  is rotated counterclockwise by 90 degrees. 
     As illustrated in  FIG. 4 , the first inertial sensor  3  has, in the plan view from the Z direction, a rectangular outer shape formed by being surrounded by a long side  31  and a short side  32  having a length different from that of the long side  31 . In the present embodiment, the long side  31  is parallel to the X direction, and the short side  32  is parallel to the Y direction. 
     The first inertial sensor  3  includes a first acceleration sensor element  30 , a first angular velocity sensor element  3   r , and a plurality of first internal electrodes  33  electrically coupled to the first acceleration sensor element  30  and the first angular velocity sensor element  3   r  by a wiring which is not illustrated. In the present embodiment, the first acceleration sensor element  30  and the first angular velocity sensor element  3   r  are each formed using a silicon substrate, and may be formed using a semiconductor substrate other than silicon or a piezoelectric substrate such as crystal. 
     The first acceleration sensor element  30  includes an X-axis acceleration sensor element  3   x  that detects acceleration in the X direction along the long side  31 , a Z-axis acceleration sensor element  3   z  that detects acceleration in the Z direction perpendicular to a plane including the long side  31  and the short side  32 , and a Y-axis acceleration sensor element  3   y  that detects acceleration in the Y direction along the short side  32 . In the present embodiment, the first acceleration sensor element  30  includes the X-axis acceleration sensor element  3   x , the Z-axis acceleration sensor element  3   z , and the Y-axis acceleration sensor element  3   y , and the first acceleration sensor element  30  may have one or more of the X-axis acceleration sensor element  3   x , the Z-axis acceleration sensor element  3   z , and the Y-axis acceleration sensor element  3   y.    
     In the present embodiment, the X-axis acceleration sensor element  3   x , the Z-axis acceleration sensor element  3   z , and the Y-axis acceleration sensor element  3   y  are disposed side by side in the Y direction along the short side  32  in order from the plus side in the Y direction toward the minus side in the Y direction. However, the disposition of the X-axis acceleration sensor element  3   x , the Z-axis acceleration sensor element  3   z , and the Y-axis acceleration sensor element  3   y  is not limited thereto, for example, the X-axis acceleration sensor element  3   x , the Z-axis acceleration sensor element  3   z , and the Y-axis acceleration sensor element  3   y  may be disposed side by side in the X direction along the long side  31 . 
     The first angular velocity sensor element  3   r  is a three-axis angular velocity sensor element that detects an angular velocity around each of the X axis, the Y axis, and the Z axis. The first acceleration sensor element  30  and the first angular velocity sensor element  3   r  are disposed side by side in the X direction along the long side  31 . The first angular velocity sensor element  3   r  may be omitted. 
     Here, a disposition of the first acceleration sensor element  30  and the first internal electrode  33  will be described. 
     The plurality of first internal electrodes  33  are disposed side by side in the X direction along the long side  31 . The first acceleration sensor element  30  and the plurality of first internal electrodes  33  are disposed side by side in the Y direction which is a direction along the short side  32 . 
     In the present embodiment, as described above, the first acceleration sensor element  30  and the plurality of first internal electrodes  33  are disposed side by side in the Y direction serving as a first direction. Further, the first acceleration sensor element  30  is disposed, in the Y direction, at a position that is closer to the third side  2 C, which is an outer edge of the printed circuit board  2 , than is the first internal electrode  33 . Accordingly, the stress caused by the difference in the thermal expansion coefficient between the metal cap  7  and the printed circuit board  2  is less likely to be applied to the first acceleration sensor element  30 , and detection accuracy of acceleration of the first inertial sensor  3  is further less likely to decrease. 
     As illustrated in  FIG. 5 , the second inertial sensor  4  has, in the plan view from the Z direction, a rectangular outer shape formed by being surrounded by a long side  41  and a short side  42  having a length different from that of the long side. In the present embodiment, the long side  41  is parallel to the Y direction, and the short side  42  is parallel to the X direction. 
     The second inertial sensor  4  includes a second acceleration sensor element  40 , a second angular velocity sensor element  4   r , and a plurality of second internal electrodes  43  electrically coupled to the second acceleration sensor element  40  and the second angular velocity sensor element  4   r  by a wiring which is not illustrated. 
     The second acceleration sensor element  40  includes a Y-axis acceleration sensor element  4   y  that detects acceleration in the Y direction along the long side  41 , a Z-axis acceleration sensor element  4   z  that detects acceleration in the Z direction perpendicular to a plane including the long side  41  and the short side  42 , and an X-axis acceleration sensor element  4   x  that detects acceleration in the X direction along the short side  42 . 
     In the present embodiment, the Y-axis acceleration sensor element  4   y , the Z-axis acceleration sensor element  4   z , and the X-axis acceleration sensor element  4   x  are disposed in the X direction along the short side  42  in order from the minus side in the X direction toward the plus side in the X direction. 
     The second angular velocity sensor element  4   r  is a three-axis angular velocity sensor element that detects an angular velocity around each of the X axis, the Y axis, and the Z axis. The second acceleration sensor element  40  and the second angular velocity sensor element  4   r  are disposed side by side in the Y direction along the long side  41 . 
     Here, a disposition of the second acceleration sensor element  40  and the second internal electrodes  43  will be described. 
     The plurality of second internal electrodes  43  are disposed side by side in the Y direction along the long side  41 . The second acceleration sensor element  40  and the plurality of second internal electrodes  43  are disposed side by side in the X direction which is a direction along the short side  42 . 
     In the present embodiment, as described above, the second acceleration sensor element  40  and the plurality of second internal electrodes  43  are disposed side by side in the X direction serving as a second direction. Further, the second acceleration sensor element  40  is disposed, in the X direction, at a position that is closer to the second side  2 B, which is an outer edge of the printed circuit board  2 , than is the second internal electrode  43 . Accordingly, the stress caused by the difference in the thermal expansion coefficient between the metal cap  7  and the printed circuit board  2  is less likely to be applied to the second acceleration sensor element  40 , and detection accuracy of acceleration of the second inertial sensor  4  is further less likely to decrease. 
     As described above, in the present embodiment, the first acceleration sensor element  30  is disposed at a position that is closer to the third side  2 C, which is an outer edge of the printed circuit board  2 , than are the plurality of first internal electrodes  33 , so that the detection accuracy of the acceleration of the first inertial sensor  3  is further less likely to decrease. Similarly, since the second acceleration sensor element  40  is disposed at a position that is closer to the second side  2 B, which is an outer edge of the printed circuit board  2 , than are the plurality of second internal electrodes  43 , the detection accuracy of the acceleration of the second inertial sensor  4  is further less likely to decrease. Accordingly, in the present embodiment, since the detection accuracy of the acceleration of each of the first inertial sensor  3  and the second inertial sensor  4  can be further less likely to decrease, the sensor module  1  having higher accuracy can be implemented. 
     The portions located at the main surface  21  side, which is the upper surface of the printed circuit board  2 , are described above. Next, portions located at a lower surface  22  side of the printed circuit board  2  will be described. 
     As illustrated in  FIGS. 2 and 3 , the semiconductor device  8  is mounted at the lower surface  22  of the printed circuit board  2 . The semiconductor device  8  is electrically coupled to the first inertial sensor  3 , the second inertial sensor  4 , and the angular velocity sensor  5  via a wiring that is not illustrated and that is provided at the printed circuit board  2 . The semiconductor device  8  is a circuit element, and is, for example, a configuration in which a bare chip, which is a semiconductor chip, is molded. The semiconductor device  8  controls driving of the first inertial sensor  3 , the second inertial sensor  4 , and the angular velocity sensor  5 , executes various types of processing such as sampling processing, zero point correction, sensitivity adjustment, filter processing, and temperature correction on detection signals from the first inertial sensor  3 , the second inertial sensor  4 , and the angular velocity sensor  5 , and outputs the processed detection signals. 
     The semiconductor device  8  combines the detection signals that have the same detection axis and that are output from the first inertial sensor  3  and the second inertial sensor  4 , so that noise included in the detection signals can be reduced and signal quality can be improved. For example, the semiconductor device  8  combines a detection signal in the X direction output from the X-axis acceleration sensor element  3   x  of the first inertial sensor  3  and a detection signal in the X direction output from the X-axis acceleration sensor element  4   x  of the second inertial sensor  4 , so that noise uncorrelated with the detection signals, such as thermal noise included in the detection signals, can be reduced, and the signal quality can be improved. 
     The external coupling terminal  292  electrically coupled to the semiconductor device  8  via a wiring which is not illustrated is provided at the lower surface  22  of the printed circuit board  2 . The external coupling terminal  292  is electrically coupled to the lead group  90  via a bonding member having electrical conductivity, which is not illustrated, such as solder. 
     Next, the lead group  90  will be described. As illustrated in  FIG. 1 , the lead group  90  includes, at the lower surface  22  of the printed circuit board  2 , a first lead group  90 A including a plurality of lead terminals  9  disposed along the first side  2 A, a second lead group  90 B including a plurality of lead terminals  9  disposed along the second side  2 B, a third lead group  90 C including a plurality of lead terminals  9  disposed along the third side  2 C, and a fourth lead group  90 D including a plurality of lead terminals  9  disposed along the fourth side  2 D. 
     The plurality of lead terminals  9  included in the lead group  90  are formed by, for example, cutting a lead frame at the time of manufacturing, and are formed of, for example, an iron-based material or a copper-based material. As illustrated in  FIGS. 2 and 3 , each of the plurality of lead terminals  9  includes a coupling portion  91  coupled to the printed circuit board  2 . The coupling portion  91  is electrically coupled to, via a bonding member having electrical conductivity, which is not illustrated, such as solder, the external coupling terminal  292  formed at the lower surface  22  of the printed circuit board  2 . 
     As described above, according to the present embodiment, the following effect can be attained. 
     In the plan view from the Z direction orthogonal to the main surface  21  of the printed circuit board  2 , the first inertial sensor  3  and the second inertial sensor  4  are disposed outside the region  243  surrounded by the line segment L 1  connecting both ends of the first recessed portion  23 A of the printed circuit board  2  in the width direction and both ends of the second recessed portion  23 B of the printed circuit board  2  in the width direction, and outside the region  244  surrounded by the line segment L 2  connecting both ends of the third recessed portion  23 C in the width direction and both ends of the fourth recessed portion  23 D in the width direction. Accordingly, the stress caused by the difference in thermal expansion coefficient between the metal cap  7  and the printed circuit board  2  is less likely to be applied to the first inertial sensor  3  and the second inertial sensor  4 . Therefore, the detection accuracy of the first inertial sensor  3  and the second inertial sensor  4  is stabilized, and the sensor module  1  having high accuracy can be implemented. 
     2. Second Embodiment 
     Next, a sensor module  1   a  according to a second embodiment will be described with reference to  FIGS. 6 to 8 . In the following description, differences from the first embodiment described above will be mainly described, and the same configurations as those according to the first embodiment are denoted by the same reference numerals, and redundant description thereof will be omitted. 
     As illustrated in  FIG. 8 , in the sensor module  1   a  according to the present embodiment, the posture of the second inertial sensor  4  is different from that according to the first embodiment. Specifically, in the plan view from the Z direction, the second inertial sensor  4  is mounted in a posture in which the first inertial sensor  3  is rotated clockwise by 90 degrees. As illustrated in  FIG. 6 , in the sensor module  1   a  according to the present embodiment, similarly to the first embodiment, the first inertial sensor  3  is disposed in the first mounting region  246 , and the second inertial sensor  4  is disposed in the third mounting region  248 . 
     First, a disposition of the first acceleration sensor element  30  and the first angular velocity sensor element  3   r  in the first inertial sensor  3  will be described. 
     As illustrated in  FIG. 7 , the configuration and posture of the first inertial sensor  3  are the same as those according to the first embodiment, and the first acceleration sensor element  30  and the first angular velocity sensor element  3   r  are disposed side by side in the X direction along the long side  31 . 
     In the present embodiment, as described above, the first acceleration sensor element  30  and the first angular velocity sensor element  3   r  are disposed side by side in the X direction serving as a third direction. Further, the first acceleration sensor element  30  is disposed, in the X direction, at a position that is closer to the first side  2 A, which is an outer edge of the printed circuit board  2 , than is the first angular velocity sensor element  3   r . Accordingly, the stress caused by the difference in the thermal expansion coefficient between the metal cap  7  and the printed circuit board  2  is less likely to be applied to the first acceleration sensor element  30 , and the detection accuracy of the acceleration of the first inertial sensor  3  is further less likely to decrease. 
     Next, a disposition of the second acceleration sensor element  40  and the second angular velocity sensor element  4   r  in the second inertial sensor  4  will be described. 
     As illustrated in  FIG. 8 , the second acceleration sensor element  40  includes the Y-axis acceleration sensor element  4   y  that detects the acceleration in the Y direction along the long side  41 , the Z-axis acceleration sensor element  4   z  that detects the acceleration in the Z direction perpendicular to the plane including the long side  41  and the short side  42 , and the X-axis acceleration sensor element  4   x  that detects the acceleration in the X direction along the short side  42 . The Y-axis acceleration sensor element  4   y , the Z-axis acceleration sensor element  4   z , and the X-axis acceleration sensor element  4   x  are disposed side by side in the X direction along the short side  42  in order from the plus side in the X direction toward the minus side in the X direction. 
     The second acceleration sensor element  40  and the second angular velocity sensor element  4   r  are disposed side by side in the Y direction along the long side  41 . 
     In the present embodiment, as described above, the second acceleration sensor element  40  and the second angular velocity sensor element  4   r  are disposed side by side in the Y direction serving as a fourth direction. The second acceleration sensor element  40  is disposed at a position that is closer to the fourth side  2 D, which is an outer edge of the printed circuit board  2 , than is the second angular velocity sensor element  4   r . Accordingly, the stress caused by the difference in the thermal expansion coefficient between the metal cap  7  and the printed circuit board  2  is less likely to be applied to the second acceleration sensor element  40 , and the detection accuracy of the acceleration of the second inertial sensor  4  is further less likely to decrease. 
     According to the present embodiment, the following effects can be attained in addition to the effect according to the first embodiment. 
     In the X direction, which is the third direction in which the first acceleration sensor element  30  and the first angular velocity sensor element  3   r  are disposed side by side, the first acceleration sensor element  30  is disposed at the position that is closer to the first side  2 A, which is an outer edge of the printed circuit board  2 , than is the first angular velocity sensor element  3   r , so that the detection accuracy of the acceleration of the first inertial sensor  3  is further less likely to decrease. Similarly, in the Y direction, which is the fourth direction in which the second acceleration sensor element  40  and the second angular velocity sensor element  4   r  are disposed side by side, the second acceleration sensor element  40  is disposed at the position closer to the fourth side  2 D, which is an outer edge of the printed circuit board  2 , than is the second angular velocity sensor element  4   r , so that the detection accuracy of the acceleration of the second inertial sensor  4  is further less likely to decrease. Accordingly, since the detection accuracy of the acceleration of each of the first inertial sensor  3  and the second inertial sensor  4  can be further less likely to decrease, the sensor module  1   a  having higher accuracy can be implemented. 
     The sensor modules  1  and  1   a  can be applied to, for example, vehicles such as construction machines and agricultural machines, moving bodies such as robots and drones, and electronic devices such as smartphones and head mounted displays.