Physical quantity sensor and physical quantity detection device

Abstract

The invention provides a physical quantity sensor and a physical quantity detection device, which prevent inclination of a weight and have small detection sensitivity deviation. A physical quantity sensor (10) is provided with: a base part (21); a support section (22) that supports the base section (21); a plate-shaped movable part (24) extending in one direction from the base part (21) via a hinge part (23); a physical quantity detection element (40) that spans the hinge section (23) and is joined to the base section (21) and the movable section (24); a package (50) that supports the support part (22) in the fixing region (25); and a weight (30) having a pair of recessed portions (32) that are recessed toward the center of gravity (80) of the weight portion (31) when viewed from a direction perpendicular to the main surface (24a) of the movable portion (24).

Description

Technical Field

[0001] The present invention relates to a physical quantity sensor and a physical quantity detection device. Background Art

[0002] For example, patent document 1 discloses a physical quantity detection device, which comprises: a base having a fixed portion and a movable portion extending to the fixed portion along a first direction via a joint portion and displacing according to a change in a physical quantity; a physical quantity detection element, which is fixed in a manner mounted on the fixed portion and the movable portion, and detects the physical quantity corresponding to the displacement of the movable portion; a weight portion, which is arranged on the movable portion; and a pillow portion, which is arranged on the base with a gap therebetween, and at least a portion of the movable portion or the weight portion is overlapped on the pillow portion when viewed from above in the direction in which the movable portion is displaced.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-145755

[0004] However, in the physical quantity detection device described in Patent Document 1, when the weight portion is fixed to the movable portion of the base, the weight portion is clamped with tweezers or the like to be fixed to the movable portion, so that the weight portion may be fixed in a manner tilted away from the first direction. Due to the tilt of the weight portion, for example, the weight portion may adhere to the adhesive used to fix the base to which the weight portion is fixed to the package, resulting in deterioration of detection sensitivity and deviation of detection sensitivity. Summary of the Invention

[0005] The physical quantity sensor comprises: a base; a supporting portion supporting the base; a plate-shaped movable portion extending from the base in one direction via a hinge portion; a physical quantity detection element spanning the hinge portion and joined to the base and the movable portion; a package supporting the supporting portion in a fixed area; and a weight having a pair of recessed portions that are respectively recessed toward the center of gravity of the weight portion when viewed in a direction perpendicular to the main surface of the movable portion.

[0006] A physical quantity detection device includes: the physical quantity sensor described above; and a processing circuit that drives the physical quantity sensor and processes a detection signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a plan view showing a schematic configuration of the physical quantity sensor according to the first embodiment.

[0008] Figure 2 yes Figure 1 Cross-sectional view along line AA.

[0009] Figure 3 It is a plan view schematically showing the structure of a weight included in the physical quantity sensor according to the first embodiment.

[0010] Figure 4 It is a plan view schematically showing the structure of a weight included in the physical quantity sensor according to the second embodiment.

[0011] Figure 5 It is an exploded perspective view of a physical quantity detection device according to a third embodiment.

[0012] Description of Reference Numerals

[0013] 10, 10a: physical quantity sensor; 20: cantilever structure; 21: base; 22: supporting part; 23: hinge part; 24: movable part; 24a: main surface; 25: fixed area; 30: weight; 31: weight part; 32: recessed part; 33: bottom; 34: surface; 40: physical quantity detection element; 41: electrode pad; 50: package; 50a: inner bottom; 51: step part; 52: internal terminal; 53: external terminal; 54: through hole; 55: accommodating space; 60: bonding part; 61, 62, 63: adhesive; 64: sealing part; 65: bonding wire; 70: cover; 80: center of gravity; 100: physical quantity detection device; 110: circuit substrate; 111: processing circuit; 120: connector substrate; 130: package base; 140: cover. DETAILED DESCRIPTION

[0014] 1. First Implementation

[0015] 1.1. Physical Quantity Sensor

[0016] First, regarding the physical quantity sensor 10 according to the first embodiment, an acceleration sensor that detects acceleration in the vertical direction is taken as an example, and reference is made to FIG. Figure 1 、 Figure 2 and Figure 3 It should be noted that Figure 1 In FIG. 1 , for convenience of explaining the internal structure of the physical quantity sensor 10 , the figure shows a state where the lower cover 70 is removed.

[0017] For ease of explanation, the X-axis, Y-axis, and Z-axis are shown as three mutually orthogonal axes in the following top views, cross-sectional views, and exploded perspective views. The direction along the X-axis is referred to as the "X direction," the direction along the Y-axis is referred to as the "Y direction," and the direction along the Z-axis is referred to as the "Z direction." The arrow side of each axis is also referred to as the "positive side," and the side opposite to the arrow is also referred to as the "negative side." The positive side in the Z direction is also referred to as "up," and the negative side in the Z direction is also referred to as "down."

[0018] The physical quantity sensor 10 of this embodiment can detect the acceleration of the physical quantity detection element 40 in the vertical direction, that is, the Z direction, as a physical quantity. Figure 1 and Figure 2 As shown, such a physical quantity sensor 10 includes a cantilever structure 20 to which a physical quantity detection element 40 and a weight 30 are fixed, a package 50 that houses the cantilever structure 20 , and a cover 70 that serves as a top cover of the package 50 .

[0019] The cantilever structure 20 is formed of a crystal substrate and includes a base 21 , a support 22 , and a cantilever. The cantilever includes a hinge 23 and a movable portion 24 .

[0020] The base 21 extends in the X direction and is connected to three support portions 22 at both ends in the X direction. It should be noted that the support portion 22 extending in the positive Y direction and the support portion 22 extending in the negative Y direction are connected to the end of the base 21 on the positive side in the X direction, and the support portion 22 extending in the positive Y direction is connected to the end of the base 21 on the negative side in the X direction.

[0021] The three support portions 22 support the base portion 21 . The base ends of the support portions 22 are connected to the base portion 21 , and the free ends thereof are provided with fixing regions 25 fixed to the step portion 51 of the package 50 by adhesive 61 .

[0022] The hinge portion 23 is disposed between the base portion 21 and the movable portion 24 , and connects the base portion 21 and the movable portion 24 .

[0023] The movable portion 24 is a plate extending from the base 21 in one direction, namely, the positive side in the Y direction, via the hinge portion 23. The movable portion 24 is disposed between two support portions 22 extending from both ends of the base 21 in the X direction toward the positive side in the Y direction.

[0024] The weight 30 is made of metal such as SUS or copper and is bonded to the upper and lower surfaces of the movable portion 24 on the free end side by an adhesive 62. Figure 3 As shown, the weight 30 has a pair of recessed portions 32 that are each recessed toward the center of gravity 80 of the weight portion 31. The pair of recessed portions 32 have a pair of bottom portions 33 that are configured so that, when viewed from a direction perpendicular to the main surface 24a of the movable portion 24, the center of gravity 80 is located within the region connecting the pair of bottom portions 33. The pair of bottom portions 33 are surfaces 34 that are parallel to each other. When viewed from a direction perpendicular to the main surface 24a of the movable portion 24, the pair of recessed portions 32 are separated from the fixed region 25 of the support portion 22.

[0025] Because the bottoms 33 of the pair of recessed portions 32 are positioned at the center of gravity 80 of the weight portion 31, when the weight 30 is clamped with tweezers or the like to be fixed to the movable portion 24, the weight 30 is lifted with good balance, and the weight 30 can be accurately positioned on the movable portion 24, thereby reducing the possibility of the weight 30 being fixed at an angle. Therefore, the adhesive 61 used to fix the cantilever structure 20 to the package 50 adhering to the weight 30 and causing deviations in detection sensitivity due to the tilt of the weight 30 can be reduced.

[0026] The physical quantity detection element 40 is formed of, for example, a double-tuning-fork crystal oscillator and detects acceleration or pressure as a physical quantity. The physical quantity detection element 40 is arranged across the hinge portion 23 and is bonded to the base portion 21 and the movable portion 24 via an adhesive 63 .

[0027] The movable portion 24 displaces in response to acceleration with the hinge portion 23 as a fulcrum, thereby generating stress in the physical quantity detection element 40 attached to the base 21 and the movable portion 24. The resonant frequency, which is the vibration frequency of the physical quantity detection element 40, changes in response to the stress applied to the physical quantity detection element 40. Acceleration can be detected based on this change in the resonant frequency.

[0028] The package 50 is made of, for example, ceramic and has a stepped portion 51 that protrudes upward from the inner bottom 50a toward the positive side in the Z direction. The cantilever structure 20 is secured to the package 50 by securing the three fixing regions 25 of the cantilever structure 20 to the stepped portion 51 with an adhesive 61. A pair of internal terminals 52 are provided on the stepped portion 51 so as to sandwich the physical quantity detection element 40 located on the base 21. The internal terminals 52 are electrically connected to the electrode pads 41 via bonding wires 65. The electrode pads 41 are electrically connected to excitation electrodes (not shown) for driving the physical quantity detection element 40. External terminals 53 are provided on the surface of the inner bottom 50a opposite the cover 70. These external terminals 53 are electrically connected to the internal terminals 52 via through electrodes and wiring (not shown).

[0029] The cover 70 is bonded to the upper surface of the package 50 via the bonding member 60, and forms a storage space 55 for accommodating the cantilever structure 20 to which the physical quantity detection element 40 and the weight 30 are fixed. A through hole 54 for airtightly sealing the storage space 55 is provided in the inner bottom 50a. A sealing member 64 is disposed in the through hole 54, heated and melted, and then solidified, thereby airtightly sealing the storage space 55.

[0030] As described above, the physical quantity sensor 10 of this embodiment has a pair of recessed portions 32 that are respectively recessed toward the center of gravity 80 of the weight portion 31 when viewed from a direction perpendicular to the main surface 24a of the movable portion 24. Therefore, when the weight 30 is clamped with tweezers or the like to be fixed to the movable portion 24, the weight 30 is lifted with good balance and can be configured to the movable portion 24 with high precision. Therefore, the situation where the weight 30 is fixed at an angle can be reduced. Therefore, the adhesive 61 used to fix the cantilever structure 20 to the package 50 adhering to the weight 30 and the deviation in detection sensitivity caused by the tilt of the weight 30 can be reduced. Therefore, the weight 30 can be configured with high precision, the tilt of the weight 30 is reduced, and the physical quantity sensor 10 with small deviation in detection sensitivity can be obtained while suppressing the increase in manufacturing costs.

[0031] 2. Second Implementation

[0032] Next, refer to Figure 4 A physical quantity sensor 10 a according to a second embodiment will be described.

[0033] It should be noted that Figure 4 It is a plan view showing the structure of a weight 30 a in a physical quantity sensor 10 a according to the second embodiment.

[0034] The physical quantity sensor 10a of this embodiment is identical to the physical quantity sensor 10 of the first embodiment, except that the structure of the recessed portion 32a of the weight 30a is different. It should be noted that the description will focus on the differences from the first embodiment, and identical items will be denoted by the same reference numerals, and their description will be omitted.

[0035] like Figure 4 As shown, regarding the weight 30a of the physical quantity sensor 10a, the following points exist: when viewed from a direction perpendicular to the main surface 24a of the movable portion 24, the bottom 33a of the recessed portion 32a is defined by a surface 34a inclined relative to the direction connecting the bottoms 33a to each other, and the center of gravity 80 is located on the line connecting the bottoms 33a to each other. In other words, the pair of recessed portions 32a are cones with a pair of points as their respective vertices, wherein the center of gravity 80 is located on the line connecting the pair of points to each other when viewed in a direction perpendicular to the main surface 24a of the movable portion 24. In other words, the recessed portions 32a are recessed into a triangular shape, and the center of gravity 80 of the weight portion 31a is located on the line connecting the triangular front end of one recessed portion 32a and the triangular front end of the other recessed portion 32a.

[0036] Since the front ends of a pair of recessed portions 32a are arranged at the position of the center of gravity 80 of the clamped weight portion 31a, when the weight 30a is clamped using tweezers or the like to fix it to the movable portion 24, the weight 30a will be lifted in a well-balanced manner, and the weight 30a can be arranged on the movable portion 24 with high precision, thereby further reducing the situation where the weight 30a is fixed at an angle.

[0037] This configuration achieves the same effects as the physical quantity sensor 10 of the first embodiment. It should be noted that the shape of the pair of recessed portions 32a, as seen when viewed from a direction perpendicular to the main surface 24a, does not need to be a strict triangle; it can simply be a shape that is inclined so as to guide tweezers or the like to the bottom portion 33a when grasping the weight 30a. In other words, the surface 34a may be curved.

[0038] 3. Third Implementation

[0039] Next, regarding the physical quantity detection device 100 according to the third embodiment, a device including three physical quantity sensors 10 is given as an example, and reference is made to FIG. Figure 5 Provide explanation.

[0040] The physical quantity detection device 100 includes three physical quantity sensors 10 and can detect physical quantities on three orthogonal axes. Note that the physical quantity in the physical quantity detection device 100 of this embodiment is acceleration.

[0041] like Figure 5 As shown, the physical quantity detection device 100 includes three physical quantity sensors 10 mounted on a circuit board 110 having a processing circuit 111 that drives the physical quantity sensors 10 and processes detection signals. The three physical quantity sensors 10 are mounted on the circuit board 110 so that their detection axes align with three orthogonal axes. The circuit board 110 is electrically connected to a connector board 120. These circuit board 110 and connector board 120 are housed and retained in a package formed by a package base 130 and a cover 140.

[0042] As described above, the physical quantity detection device 100 of this embodiment can detect acceleration along the three axes with high accuracy because the three physical quantity sensors 10, each equipped with a weight 30 with high precision, are installed along three axes that are orthogonal to each other and serve as detection axes. The same applies to the case where the physical quantity detection device 100 includes three physical quantity sensors 10a.

Claims

1. A physical quantity sensor, characterized in that: have: base; a supporting portion supporting the base; A plate-shaped movable portion extending in one direction from the base portion via a hinge portion; a physical quantity detecting element spanning the hinge portion and engaging with the base portion and the movable portion; a packaging member supporting the support portion in a fixing area; as well as The weight has a pair of recessed portions each recessed toward a center of gravity of the weight portion when viewed in a direction perpendicular to a main surface of the movable portion.

2. The physical quantity sensor according to claim 1, wherein The pair of recessed portions have a pair of bottom portions, and the pair of bottom portions are arranged so that the center of gravity is located in a region connecting the pair of bottom portions when viewed from a direction perpendicular to the main surface of the movable portion.

3. The physical quantity sensor according to claim 2, wherein: The pair of bottoms are surfaces parallel to each other.

4. The physical quantity sensor according to claim 1, wherein The pair of recessed portions are tapered with a pair of points as respective vertices when viewed from a direction perpendicular to the main surface of the movable portion, and the center of gravity is located on a line connecting the pair of points.

5. The physical quantity sensor according to any one of claims 1 to 4, characterized in that The pair of recessed portions are separated from the fixed region when viewed from a direction perpendicular to the main surface of the movable portion.

6. A physical quantity detection device, characterized in that: have: The physical quantity sensor according to any one of claims 1 to 5; and The processing circuit drives the physical quantity sensor and processes the detection signal.

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