JP2017102004A - Acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acceleration sensor capable of reducing the possibility of occurrence of resonance due to an impact from the outside while reducing an influence of a thermal stress.SOLUTION: An acceleration sensor comprises a sensor chip 10, a base material 20, a package 30, first adhesive 40, second adhesive 50 and a spacer 60. The sensor chip 10 is configured to convert acceleration into an electric signal, and mounted on the base material 20. The package 30 is configured to hold the base material 20. The first adhesive 40 is arranged between the sensor chip 10 and the base material 20, and configured to adhere the sensor chip 10 to the base material 20. The second adhesive 50 is arranged between the base material 20 and the package 30, and configured to adhere the base material 20 to the package 30. The spacer 60 is arranged between the base material 20 and the package 30, and configured to keep a gap between the base material 20 and the package 30 constant. The elastic modulus of each of the first adhesive 40 and the second adhesive 50 is lower than that of the base material 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an acceleration sensor, and more particularly to an acceleration sensor that reduces the influence of resonance and thermal stress.

  Conventionally, the acceleration sensor of Patent Document 1 includes a sensor chip, a pedestal, a substrate, and an adhesive. The sensor chip is an element that detects the magnitude of acceleration by converting impact acceleration into an electrical signal. The pedestal supports the sensor chip. The substrate supports a pedestal that supports the sensor chip. The adhesive bonds the sensor chip and the base and bonds the base and the substrate.

Japanese Patent Laid-Open No. 10-54843

  In the conventional acceleration sensor, when thermal stress due to the difference in thermal expansion coefficient between the sensor chip and the pedestal occurs, the sensor chip and the pedestal are bonded together with an adhesive, so that the generated thermal stress is transmitted to the sensor chip. End up. Then, the sensor chip is cracked by the thermal stress, which may cause a failure of the acceleration sensor.

  Moreover, there is a concern that resonance occurs when the frequency of the applied impact matches the resonance frequency of the acceleration sensor. Due to this resonance, an error may occur in the detection accuracy of the acceleration sensor, or the acceleration sensor may be deformed and cause a failure.

  In view of the above problems, an object of the present invention is to provide an acceleration sensor that can reduce the possibility of resonance due to an external impact while reducing the influence of thermal stress.

  The present invention employs the following means in order to achieve the above-described object.

  The invention according to claim 1 is an acceleration sensor that measures the acceleration of an object, a sensor chip that is an element that converts acceleration into an electrical signal, a base material on which the sensor chip is mounted, and a package that holds the base material And a first adhesive that is disposed between the sensor chip and the base material and bonds the sensor chip and the base material, and a second adhesive that is disposed between the base material and the package and bonds the base material and the package. An adhesive, and a spacer that is disposed between the base material and the package and that keeps a distance between the base material and the package constant, and the elastic modulus of the first adhesive and the second adhesive is The acceleration sensor is lower than the elastic modulus.

  According to this invention, since the elastic modulus of the first adhesive and the second adhesive is lower than the elastic modulus of the base material, the stress generated by the thermal expansion of the base material or the package can be reduced. Can be absorbed with 2 adhesives.

  Here, in order to prevent the acceleration sensor from resonating due to external vibration, it is better that the resonance frequency of the acceleration sensor is high. However, if both adhesives are too thick, the resonance frequency of the acceleration sensor is lowered. . Therefore, although it is preferable that the thickness of both adhesives is thin, conversely, if it is too thin, adhesive strength cannot be secured. That is, it is desirable that the thicknesses of the first adhesive and the second adhesive be as thin as possible to ensure the adhesive force. Therefore, a spacer is disposed between the base material and the package. By adjusting the distance between the base material and the package to a constant value by the spacer, the thickness of the second adhesive can be accurately controlled so that the resonance frequency of the acceleration sensor does not match the frequency of the impact from the outside. .

  Therefore, even when the resonance frequency of the acceleration sensor is lowered by using the first adhesive and the second adhesive whose elastic modulus is lower than that of the base material, the resonance frequency is secured while the adhesive force is secured by the spacer. Can be kept high. Therefore, it is possible to reduce the possibility of resonance due to an external impact while reducing the influence of thermal stress.

It is sectional drawing of the acceleration sensor 1 of 1st Embodiment. It is a figure when the acceleration sensor 1 of 1st Embodiment is seen from the II direction of FIG. It is the figure which showed the relationship between the thickness of the 2nd adhesive agent 50 of the acceleration sensor 1 of 1st Embodiment, and the resonant frequency of the acceleration sensor 1. FIG. It is sectional drawing of the acceleration sensor 2 of 2nd Embodiment. It is a figure when the acceleration sensor 2 of 2nd Embodiment is seen from the V direction of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in the drawings are denoted by the same reference numerals as much as possible, and redundant description will be omitted.

(First embodiment)
The configuration of the acceleration sensor 1 of the first embodiment will be described with reference to FIG.

  The acceleration sensor 1 is mainly used for impact detection of a safety device mounted on a vehicle. As its function, it is possible to detect various movement information such as vibration, impact and tilt. And the acceleration sensor 1 of 1st Embodiment is provided with the sensor chip 10, the base material 20, the package 30, the 1st adhesive agent 40, the 2nd adhesive agent 50, and the spacer 60, as shown in FIG.

  The sensor chip 10 is an element that converts movement information such as an impact applied from the outside into an electric signal and measures the acceleration of the object. It is a semiconductor sensor mainly using Si (Silicon) crystal as a substrate material, and is manufactured by microfabrication using various MEMS (Micro Electro Mechanical Systems) technologies.

  Further, as an acceleration detection method of the sensor chip 10 of the first embodiment, a capacitance type sensor that detects a change in capacitance as acceleration is used. In the structure of the capacitive sensor, two pairs of electrodes, that is, a movable electrode that moves when acceleration is applied and a fixed electrode that does not react to acceleration are opposed to each other. The capacitance of these two pairs of opposing electrodes changes due to acceleration from the outside, and the change in capacitance is detected as an electrical signal. At this time, the damper is designed when the movable electrode and the fixed electrode are configured so that the frequency due to the impact from the outside does not match the resonance frequency of the sensor chip 10 itself.

  The base material 20 is a circuit board on which the sensor chip 10 is mounted. Therefore, the base material 20 has wiring and is electrically connected to the sensor chip 10. The wiring structure is called a printed circuit board, in which insulating layers that are insulator layers and wiring layers in which wiring is formed are alternately stacked. In the first embodiment, a ceramic material is mainly used for the insulating layer. The ceramic material has a modulus of gigapascal order and can be said to be a hard material as compared with other general insulating materials. The wiring layer is formed on the insulating layer by various fine processing techniques, and materials such as aluminum and copper are used as the wiring material.

  The package 30 holds the base material 20 on which the sensor chip 10 is mounted, and prevents the sensor chip 10 described above from being exposed to the external environment. However, a housing space 30b for housing the sensor chip 10 and the base material 20 is formed in the package 30, and the sensor chip 10 is exposed in the housing space 30b. Since the accommodation space 30b is a space isolated from the external environment, the sensor chip 10 is not directly exposed to the external environment. The material of the package 30 is resin, and it is formed by various resin molding techniques.

  The 1st adhesive agent 40 is arrange | positioned between the sensor chip 10 and the base material 20, and has adhere | attached both. Silicone is the most suitable material for the first adhesive 40.

  Silicone is a general term for artificial polymer compounds having a main skeleton of a siloxane bond, and is often used as a rubber material for general purposes. Therefore, the elastic modulus of the first adhesive 40 is smaller than the elastic modulus of the base material 20 using the above ceramic material. Desirably, the elastic modulus of the first adhesive 40 may be a value on the order of megapascals. Therefore, the stress generated by the thermal expansion of the base material 20 is absorbed by the first adhesive 40 and the stress acting on the sensor chip 10 can be reduced. In addition, about the thickness of the 1st adhesive agent 40, it is the thickness which can reduce the stress which acts on the sensor chip 10, and can ensure the adhesive force of the sensor chip 10 and the base material 20. FIG. Specifically, it is thinner than the thickness of the second adhesive 50 described later, and is desirably thinner than the thickness of the sensor chip 10 and the thickness of the base material 20.

  The 2nd adhesive agent 50 is arrange | positioned between the base material 20 and the package 30, and has adhere | attached both. As the material of the second adhesive 50, the above-mentioned silicone is optimal. Therefore, the elastic modulus of the second adhesive 50 is smaller than the elastic modulus of the base material 20 using the ceramic material. Desirably, the elastic modulus of the second adhesive 50 may be a value on the order of megapascals. More preferably, the elastic modulus of the second adhesive 50 is larger than the elastic modulus of the first adhesive 40. Further, the second adhesive 50 is applied to a surface facing the base material 20 on a holding surface 30 a that is a surface for holding the base material 20 of the package 30.

  Here, the relationship between the thickness of the second adhesive 50 and the resonance frequency of the acceleration sensor 1 will be described. The thickness of the second adhesive 50 and the resonance frequency of the acceleration sensor 1 have a relationship as shown in FIG. That is, as the thickness of the second adhesive 50 increases, the resonance frequency of the acceleration sensor 1 decreases. Therefore, it is necessary to secure a resonance frequency equal to or higher than the dotted line L1 in FIG. 3 so that the resonance frequency of the acceleration sensor 1 does not coincide with the frequency of the impact from the outside. Further, in order to increase the resonance frequency of the acceleration sensor 1, the thickness of the second adhesive 50 may be reduced. However, as the thickness of the second adhesive 50 is reduced, the base material 20 and the package 30 may be reduced. Adhesive strength decreases. Therefore, the thickness of the second adhesive 50 has a lower limit value. The dotted line L2 in FIG. 3 shows the lower limit value that can secure the above-mentioned adhesive force. If the thickness of the second adhesive 50 is made thicker than this dotted line L2, the above-mentioned adhesive force can be ensured. . Therefore, in order to prevent the resonance frequency of the acceleration sensor 1 and the frequency of the external shock from matching, and to ensure the above-described adhesive force, the second adhesion is performed within the range surrounded by the dotted line L2 and the dotted line L3 in FIG. It is necessary to control the thickness of the agent 50.

  Note that the thickness of the first adhesive 40 is also related to the resonance frequency of the acceleration sensor 1, but the thickness of the first adhesive 40 prevents the stress from being transmitted to the sensor chip 10 compared to the second adhesive 50. The second adhesive 50 has a smaller influence on the resonance frequency. That is, the thickness of the first adhesive 40 is such that the stress is prevented from being transmitted, and the thickness of the second adhesive 50 is adjusted by the spacer 60 so that the resonance frequency of the acceleration sensor 1 is reduced by an external impact. Over frequency.

  The spacer 60 is disposed between the base material 20 and the package 30 and is mainly made of a resin material. Here, as shown in FIG. 2, a chain line CL1 passing through the center of gravity of the base material 20 in a direction parallel to the mounting surface 20a on which the sensor chip 10 is mounted, and a direction parallel to the mounting surface 20a on which the sensor chip 10 is mounted. Then, a chain line CL2 passing through the center of gravity of the base material 20 and perpendicular to the chain line CL1 is defined. Four spacers 60 are arranged symmetrically with respect to the chain line CL1 and the chain line CL2, and one spacer 60 is also arranged at the intersection of the chain line CL1 and the chain line CL2.

  Further, as the function of the spacer 60, one of the spacers 60 is in contact with the base material 20, and the other is in contact with the package 30, so that the height of the spacer 60 is between the base material 20 and the package 30. An interval of minutes is born. And the above-mentioned 2nd adhesive agent 50 is arrange | positioned between the base material 20 and the package 30, and when the space | interval for the height of the spacer 60 leaves | separates, the thickness of the 2nd adhesive agent 50 is unambiguous. It has been decided. Further, the interval formed by the spacer 60 is constant everywhere in the space where the base member 20 and the package 30 are opposed to each other. That is, by arranging the spacer 60 between the base material 20 and the package 30, the thickness of the second adhesive 50 can be made unambiguous and constant, so that the thickness of the second adhesive 50 can be controlled. it can.

  Although the spacer 60 is a separate member from the base material 20 and the package 30 in the first embodiment, the base material 20 may be provided with a protrusion having the function as the spacer 60 described above. A protrusion as the above-described spacer 60 may be formed on the package 30. That is, the spacer 60 is integrated with the base material 20 and may contact the holding surface 30 a of the package 30. Furthermore, the spacer 60 may be integrated with the package 30 and may be in contact with the opposite surface of the mounting surface 20 a of the base material 20. The shape of the spacer 60 is not limited to the rectangular parallelepiped shape as in the first embodiment, and may be a cylindrical shape or a spherical shape. The dimensions of the spacer 60 such as length, width, and height can be designed as appropriate.

  In the first embodiment, the five spacers 60 are provided. However, the number of the spacers 60 is not limited to five and may be at least one. Furthermore, it is more preferable that the spacer 60 is provided between the base material 20 and the package 30 in a concentric shape centering on the center of gravity of the base material 20 as compared with the arrangement of the spacer 60 of the first embodiment. This is because the three spacers 60 are arranged concentrically with the center of gravity of the base material 20 as the center, so that the spacer 60 can reliably abut against the base material 20 and the package 30 and the thickness of the second adhesive 50 can be defined. is there. Furthermore, since the spacer 60 is disposed so as to surround the center of gravity, the base material 20 can be stably held. In short, in the present invention, the arrangement and number of the spacers 60 are not limited to those in the first embodiment, and the functions of the spacers 60 described above may be satisfied.

(Operational effects of the first embodiment)
Hereinafter, the effect of the acceleration sensor 1 of 1st Embodiment is demonstrated.

  According to the present embodiment, since the first adhesive 40 and the second adhesive 50 have a lower elastic modulus than the base material 20, the stress generated by the thermal expansion of the base material 20 and the package 30 is the first adhesive. 40 and the second adhesive 50 can absorb. Here, if the thickness of the second adhesive 50 is too thick, the resonance frequency of the acceleration sensor 1 is lowered, and conversely, if it is too thin, the adhesive force cannot be secured. Therefore, it is preferable that the thickness of the second adhesive 50 is thin, but it is desirable that the thickness of the second adhesive 50 be as thin as possible to ensure an adhesive force. Therefore, the distance between the base material 20 and the package 30 is adjusted to a constant value by the spacer 60. Then, the thickness of the second adhesive 50 is uniquely determined within the design region between the dotted line L2 and the dotted line L3 in FIG. 3 so that the resonance frequency of the acceleration sensor 1 and the frequency of the impact from the outside do not match. be able to. Therefore, since the thickness of the second adhesive 50 can be accurately controlled within the above design area, the acceleration sensor 1 is less affected by thermal stress and the possibility of resonance due to external impact is reduced. can do.

  Furthermore, according to the present embodiment, since the sensor chip 10 is exposed in the accommodation space 30b formed by the package 30, the thermal stress generated in the base material 20 is absorbed by the first adhesive 40, so that the sensor The thermal stress transmitted to the chip 10 can be reduced.

  More specifically, in the conventional general acceleration sensor 1, the sensor chip 10 is covered with a mold resin in order to protect the sensor chip 10 from the outside air. In such a conventional acceleration sensor 1, when thermal stress is generated due to differences in thermal expansion coefficients among the sensor chip 10, the base material 20, and the package 30, the stress is transmitted to the mold resin and applied to the entire sensor chip 10. . Therefore, there is a concern that the sensor chip 10 may be damaged by thermal stress. Therefore, in this embodiment, the sensor chip 10 is not covered with the mold resin and is exposed in the accommodation space 30b. According to this, since the inside of the accommodation space 30b is a space isolated from the external environment, the sensor chip 10 can be protected from the external environment. Further, in order to transmit the generated thermal stress to the sensor chip 10 without being covered with the mold resin, it is transmitted via the first adhesive 40 and the second adhesive 50, and these adhesives. Absorbs thermal stress. Therefore, the possibility of breakage of the sensor chip 10 due to the above-described thermal stress can be reduced while protecting the sensor chip 10 from the external environment.

  In the first embodiment, a ceramic material is used as the base material 20 and silicone is used as the first adhesive 40 and the second adhesive 50. However, the present invention is not limited to these in order to achieve the effects of the present invention. There is nothing. That is, various materials may be appropriately selected so that the elastic modulus of the first adhesive 40 and the second adhesive 50 is lower than the elastic modulus of the base material 20.

(Second Embodiment)
The configuration of the acceleration sensor 2 of the second embodiment will be described with reference to FIG. In addition, description about the same structure as 1st Embodiment is abbreviate | omitted.

  Unlike the first embodiment, the package 30 of the second embodiment has a recessed surface 31 and an adhesive arrangement surface 32. The recessed surface 31 is a surface that is recessed in a direction perpendicular to the holding surface 30 a that is a surface that holds the base material 20. The adhesive placement surface 32 is a surface on which the second adhesive 50 is placed on the holding surface 30a. Then, at least three spacers 60 are arranged on the adhesive arrangement surface 32 on the circumference of a concentric circle centered on the center of gravity of the base material 20. Hereinafter, the arrangement of the recessed surface 31, the adhesive arrangement surface 32, and the spacer 60 will be described.

  The recessed surface 31 refers to a surface that is recessed in a direction perpendicular to the holding surface 30 a that is a surface that holds the base material 20 of the package 30. The recessed surface 31 has a bottom surface 31a, a first side surface 31b, and a second side surface 32b.

  The bottom surface 31a faces the base material 20 and is below the holding surface 30a with respect to the direction perpendicular to the holding surface 30a. The first side surface 31 b is one side surface of the recessed surface 31, and the second side surface 31 c is the other side surface of the recessed surface 31. The hollow surface 31 has a rectangular cross section as shown in FIG. 4 and has a rectangular shape when viewed from above as shown in FIG. In the second embodiment, the recessed surface 31 has a rectangular shape as described above. However, the present invention is not limited to this, and the cross section may be an arc shape or a taper shape, or may be an ellipse or a rhombus when viewed from above. The design can be changed as appropriate.

  The depression surface 31 is not coated with the second adhesive 50, and has a space surrounded by the base material 20, the bottom surface 31a, the first side surface 31b, and the second side surface 31c. That is, the base material 20 and the bottom surface 31a are separated by an amount corresponding to the thickness of the second adhesive 50 plus the depth of the depression of the depression surface 31, and a space having a predetermined width is formed. Therefore, in 2nd Embodiment, the circuit element of the magnitude | size which can be accommodated in this space can be mounted in the back side of the mounting surface in which the sensor chip of the base material 20 is mounted.

  The adhesive arrangement surface 32 in which the second adhesive 50 is applied to the holding surface 30 a is a surface that bonds the package 30 and the base material 20. That is, as shown in FIG. 5, the second adhesive 50 is applied to the surface of the holding surface 30a facing the base member 20, and is not applied to the bottom surface 31a as described above. In the second embodiment, the adhesive placement surface 32 means the entire surface of the holding surface 30a facing the base material 20, but is not limited to being applied to the entire surface, and It may be applied to the part.

  Three or more spacers 60 are arranged on the circumference of a circle O centering on the center of gravity G of the base material 20 on the adhesive arrangement surface 32 described above. Further, if a part of the spacer 60 is on the circumference of the circle O, it can be said that the spacer 60 is arranged on the circumference of the circle O. The spacer 60 is arranged without being biased to one side through the recessed surface 31. In other words, there are the adhesive placement surfaces 32 on both sides of the first side surface 31b or the second side surface 31c, but the spacer 60 is not disposed only on the adhesive placement surface 32 on one side. That is, when the number of the spacers 60 is an even number, half of the spacers are arranged on one adhesive arrangement surface 32 and the other half are arranged on the other. When the number of spacers 60 is an odd number, first, half as in the case of the above-described even number, and the remaining one may be appropriately disposed. The radius of the circle O may be a part of the circumference of the circle O on the adhesive placement surface 32.

(Operational effect of the second embodiment)
Hereinafter, the function and effect of the second embodiment will be described.

  In the second embodiment, the package 30 includes a recessed surface 31 that is recessed in a direction perpendicular to the holding surface 30a that is a surface that holds the base material 20, and the second adhesive 50 on the holding surface 30a. And an adhesive arrangement surface 32 which is a surface.

  According to this, even when the base material 20 warps due to an external temperature change, the thickness of the second adhesive 50 arranged on the adhesive arrangement surface 32 can be made constant.

  More specifically, in the acceleration sensor 1 of the first embodiment, thermal stress is generated in the base material 20 due to temperature changes in the external environment, and the base material 20 may be warped. When the base material 20 is warped, the distance between the base material 20 and the package 30 is different between the center and the end of the base material 20. Therefore, there is a concern that the thickness of the second adhesive 50 described above cannot be made constant, or peeling occurs at the interface between the second adhesive 50 and the base material 20 or the interface between the second adhesive 50 and the package 30. The

  Therefore, in the present embodiment, the package 30 has the recessed surface 31 and the adhesive placement surface 32 described above. According to this, although the said space | interval near the center of the base material 20 changes most greatly by curvature, since the 2nd adhesive agent 50 does not exist in the hollow surface 31, the above-mentioned space | interval change by curvature will be 2nd adhesion. The effect on the adjustment of the thickness of the agent is small. Therefore, since it can prevent that the space | interval of the base material 20 and the package 30 changes a lot by curvature, the thickness of the 2nd adhesive agent 50 mentioned above can be adjusted accurately.

  In the second embodiment, at least three spacers 60 are arranged on the adhesive arrangement surface 32.

  According to this, it is possible to prevent the interval between the base material 20 and the package 30 from becoming constant due to the inclination of the base material 20 as compared with the case where there are two spacers 60. That is, by arranging three or more spacers 60, it is possible to prevent the base material 20 from being inclined and to keep the distance between the base material 20 and the package 30 constant.

  Furthermore, in the second embodiment, the spacer 60 is disposed on the circumference of a circle centered on the center of gravity of the base material 20. Since it is considered that the warp mainly occurs around the center of gravity of the base material 20, the distance between the base material 20 and the package 30 becomes wider toward the end of the base material 20 far from the center of gravity. Therefore, when the spacers 60 are arranged on the circumference of a circle centered on the center of gravity, the thickness of the second adhesive 50 at the locations where the spacers 60 are arranged can be made substantially uniform even when the base material 20 is warped.

  Therefore, according to the acceleration sensor 2 of 2nd Embodiment, the effect of the above-mentioned 1st Embodiment can be show | played, reducing the influence of the curvature of the base material 20. FIG.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made as illustrated above. In addition, not only combinations of parts that clearly indicate that the combination is possible in each embodiment, but also a combination of the embodiments even if not clearly indicated, unless there is a problem with the combination. It is also possible.

  Moreover, the thing for vehicle-mounted is considered as a use of the acceleration sensor of this invention. Since the vehicle is equipped with an internal combustion engine that becomes hot when driven, it can be said that when the acceleration sensor is mounted on the vehicle, it is mounted in an environment where the temperature change is very large. Since it is used in an environment where the temperature change is large, the acceleration sensor is greatly affected by the above-described thermal stress.

  Furthermore, an in-vehicle acceleration sensor is required to have a resonance frequency sufficiently higher than the frequency of vibration received from the outside. This is because an in-vehicle acceleration sensor is mounted on a safety device such as an air bag and has a role of detecting an impact at the time of a vehicle collision. Here, when the acceleration sensor resonates due to weak vibrations other than impact from the outside, for example, impact or engine vibration when the vehicle rides on a step, the weak vibration is amplified by resonance. Then, since the acceleration detected by the acceleration sensor is very large due to the amplified weak vibration, the safety device detects that a vehicle collision has occurred. Therefore, the resonance frequency of the acceleration sensor must be set high so that the frequency of the weak vibration does not match the resonance frequency of the acceleration sensor.

  Because of the above-described background, the above-described action is achieved when the acceleration sensor of the present invention, which has both the functions of reducing the influence of thermal stress and setting the optimum resonance frequency, is used for vehicle mounting. The effect can be fully achieved. Specific examples of the use of the acceleration sensor mounted on the vehicle include detection of impact when driving an airbag, detection of acceleration of a skid prevention device, and detection of acceleration of an ABS (Antilock Break System) device.

DESCRIPTION OF SYMBOLS 10 ... Sensor chip, 20 ... Base material, 30 ... Package, 40 ... 1st adhesive agent,
50 ... second adhesive, 60 ... spacer

Claims (5)

In an acceleration sensor that measures the acceleration of an object,
A sensor chip (10) which is an element for converting the acceleration into an electrical signal;
A base material (20) on which the sensor chip is mounted;
A package (30) for holding the base material;
A first adhesive (40) disposed between the sensor chip and the base material to bond the sensor chip and the base material;
A second adhesive (50) disposed between the base material and the package and bonding the base material and the package;
A spacer (60) disposed between the base material and the package and maintaining a constant distance between the base material and the package,
The first and second adhesives have an elastic modulus lower than that of the base material. In the package, an accommodation space (30b) for accommodating the sensor chip, the base material, the first adhesive, and the second adhesive is formed,
The acceleration sensor according to claim 1, wherein the sensor chip is exposed in the housing space. The package is
A recessed surface (31) which is disposed facing the base material and is recessed in a direction perpendicular to the holding surface (30a) which is a surface for holding the base material;
The acceleration sensor according to claim 1, further comprising an adhesive arrangement surface (32) that is a surface on which the second adhesive is arranged on the holding surface.   The acceleration sensor according to claim 3, wherein at least three spacers are arranged on the adhesive arrangement surface.   The acceleration sensor according to claim 4, wherein the spacer is disposed on a circumference of a circle centered on the center of gravity of the base material.

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