Force sensor device

Abstract

To provide a force sensor device which has a substrate having such a shape as to suppress creeping-up of a resin.SOLUTION: A force sensor device has a sensor chip 110 for detecting displacement in a predetermined axial direction, a strain body 20 for transmitting applied force to the sensor chip, and a substrate 30 for inputting and outputting a signal from / to the sensor chip. The strain body has a first column 22a and a second column 22b, a first beam 23a for connecting the first column and the second column, and a first input part 24a that projects toward the upper part of the first beam and to which force is applied. The substrate has a first electrode arrangement part 61 fixed to the upper surface of the first column, and a first side face fixation part 30e which extends from the first electrode arrangement part and is fixed to the first side face of the first column; a contour of the first electrode arrangement part includes a first part 611 as a boundary between the first part and the first side face fixation part, and a second part 612 continued to the first end on the first input part side of the first part; and the second part has a part which passes through the first end, and protrudes to the first input part side with respect to a first virtual straight line L1 drawn in a direction perpendicular to the longitudinal direction of the first beam.SELECTED DRAWING: Figure 18

Description

[Technical Field]

[0001] The present invention relates to a force sensor device. [Background technology]

[0002] A force sensor device has been known that includes a sensor chip that detects displacement in a predetermined axial direction and a strain generator that transmits applied force to the sensor chip. This force sensor device has a substrate on which active components electrically connected to the sensor chip are mounted, and the substrate is fixed to the upper surface of the column of the strain generator with a resin adhesive. Furthermore, electrodes are arranged on the portion of the substrate that is fixed to the upper surface of the column (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-56684 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if a large amount of resin is applied to the top surface of the pillar, some of the resin may creep up onto the top surface of the substrate and reach the electrode, making the electrode unusable for electrical connection.

[0005] The present invention has been made in view of the above points, and has an object to provide a force sensor device having a substrate with a shape that can prevent resin from creeping up. [Means for solving the problem]

[0006] The force sensor device (1) includes a sensor chip (110) that detects displacement in a predetermined axial direction, a strain generator (20) that transmits an applied force to the sensor chip (110), and a substrate (30) that inputs and outputs signals to and from the sensor chip (110). The strain generator (20) includes a first pillar (22a) and a second pillar (22b) that are arranged adjacent to the periphery of the sensor chip (110) in a plan view, a first beam (23a) that connects the first pillar (22a) and the second pillar (22b) and that deforms when an applied force is applied, and a first input portion (24a) that projects upward from the center of the longitudinal direction of the first beam (23a) and to which a force is applied. The substrate (30) includes: The first pillar (22a) includes a first electrode arrangement portion (61) fixed to the upper surface thereof, and a first side surface fixing portion (30e) extending from the first electrode arrangement portion (61) and fixed to a first side surface of the first pillar (22a). In a plan view, the contour of the first electrode arrangement portion (61) includes a first portion (611) that forms the boundary with the first side surface fixing portion (30e) and a second portion (612) that is continuous with a first end portion of the first portion (611) on the first input portion (24a) side. In a plan view, the second portion (612) has a portion that protrudes toward the first input portion (24a) with respect to a first virtual straight line (L1) that passes through the first end portion and is drawn in a direction perpendicular to the longitudinal direction of the first beam (23a).

[0007] The reference symbols in parentheses are added for ease of understanding, are merely examples, and are not limited to the illustrated embodiment. [Effects of the Invention]

[0008] According to the disclosed technique, it is possible to provide a force sensor device having a substrate with a shape that can prevent resin from creeping up. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view illustrating a force sensor device according to an embodiment of the present invention; [Figure 2] 1 is a diagram illustrating a force sensor device according to an embodiment of the present invention; [Figure 3]FIG. 2 is a circuit block diagram illustrating active components 32 to 35. [Figure 4] FIG. 1 is a view of the sensor chip 110 as seen from above in the Z-axis direction. [Figure 5] FIG. 1 is a view of the sensor chip 110 as seen from below in the Z-axis direction. [Figure 6] 2 is a diagram illustrating an example of the arrangement of piezoresistance elements of the sensor chip 110. FIG. [Figure 7] 2 is a diagram illustrating an example of electrode arrangement and wiring in a sensor chip 110. FIG. [Figure 8] 2 is an enlarged plan view illustrating a temperature sensor of the sensor chip 110. FIG. [Figure 9] 1 is a diagram (part 1) illustrating a strain element 20. FIG. [Figure 10] FIG. 2 is a diagram (part 2) illustrating the strain element 20. [Figure 11] 10 is a diagram (part 3) illustrating the strain element 20. FIG. [Figure 12] 1A to 1C are diagrams illustrating a manufacturing process of the force sensor device 1 (part 1). [Figure 13] 10A to 10C are diagrams (part 2) illustrating the manufacturing process of the force sensor device 1. [Figure 14] 10A to 10C are diagrams (part 3) illustrating the manufacturing process of the force sensor device 1. [Figure 15] 10A to 10C are diagrams illustrating the manufacturing process of the force sensor device 1 (part 4). [Figure 16] FIG. 3 is a partially enlarged view of FIG. 2. [Figure 17] FIG. 17 is a cross-sectional view taken along line DD in FIG. [Figure 18] FIG. 17 is a partially enlarged view of FIG. [Figure 19] FIG. 19 is a partially enlarged view of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations may be omitted.

[0011] (Schematic configuration of the force sensor device 1) FIG. 1 is a perspective view illustrating a force sensor device according to this embodiment. FIG. 2 is a diagram illustrating the force sensor device according to this embodiment, with FIG. 2(a) being a plan view and FIG. 2(b) being a side view. Referring to FIGS. 1 and 2, the force sensor device 1 has a sensor chip 110, a strain element 20, and a substrate 30. The force sensor device 1 is a multi-axis force sensor device that is mounted on the arm or fingers of a robot used in machine tools, for example.

[0012] The sensor chip 110 has the function of detecting displacement in a maximum of six predetermined axial directions. As shown in Fig. 1 and Fig. 4 described later, the force in the X-axis direction is defined as Fx, the force in the Y-axis direction as Fy, and the force in the Z-axis direction as Fz. Furthermore, the moment of rotation about the X-axis is defined as Mx, the moment of rotation about the Y-axis as My, and the moment of rotation about the Z-axis as Mz.

[0013] The strain-generating body 20 has a function of transmitting the applied force to the sensor chip 110. In the following embodiments, as an example, a case where the sensor chip 110 detects six axes will be described, but the present invention is not limited to this, and the sensor chip 110 can also be used to detect, for example, three axes by selecting an axis to detect from forces in the X-axis, Y-axis, and Z-axis directions, and moments of X-axis rotation, Y-axis rotation, and Z-axis rotation.

[0014] The sensor chip 110 is adhered to the upper surface of the flexure body 20 so as not to protrude from the flexure body 20. One end of a substrate 30, which inputs and outputs signals to and from the sensor chip 110, is adhered in an appropriately bent state to the upper surface and each side surface of the flexure body 20. The sensor chip 110 and each electrode 31 of the substrate 30 are electrically connected by bonding wires or the like (not shown).

[0015] Active components 32 to 35 are disposed on the side surfaces of the flexure body 20. Specifically, the active components 32 to 35 are mounted on one surface of a substrate 30 (for example, a flexible printed circuit board), and the other surface of the substrate 30 is fixed to the side surface of the flexure body 20. The active components 32 to 35 are electrically connected to the corresponding electrodes 31 via wiring patterns (not shown) formed on the substrate 30.

[0016] More specifically, active components 32 are mounted in an area of ​​the substrate 30 that is located on the first side surface of the flexure body 20. Active components 33 and passive components 39 are mounted in an area of ​​the substrate 30 that is located on the second side surface of the flexure body 20. Active components 34 and passive components 39 are mounted in an area of ​​the substrate 30 that is located on the third side surface of the flexure body 20. Active components 35 and passive components 39 are mounted in an area of ​​the substrate 30 that is located on the fourth side surface of the flexure body 20. Note that, in addition to the active components 32, passive components 39 may also be mounted in the area of ​​the first side surface of the flexure body 20, as necessary.

[0017] Fig. 3 is a circuit block diagram illustrating the active components 32 to 35. As shown in Fig. 3, the active component 33 is electrically connected to the sensor chip 110, and receives, for example, an analog electrical signal from a bridge circuit that detects a force Fx in the X-axis direction output from the sensor chip 110, and an analog electrical signal from a bridge circuit that detects a force Fy in the Y-axis direction output from the sensor chip 110. The active component 33 is, for example, a control IC that has the function of converting the analog electrical signal output from the sensor chip 110 into a digital electrical signal, internally performing temperature correction, amplitude correction, etc., and outputting the digital electrical signal.

[0018] The active component 34 is electrically connected to the sensor chip 110, and receives, for example, an analog electrical signal from a bridge circuit that detects a force Fz in the Z-axis direction output from the sensor chip 110, and an analog electrical signal from a bridge circuit that detects a moment Mx of rotation about the X-axis output from the sensor chip 110. The active component 34 is, for example, a control IC that has the function of converting the analog electrical signal output from the sensor chip 110 into a digital electrical signal, internally performing temperature correction, amplitude correction, etc., and outputting the digital electrical signal.

[0019] The active component 35 is electrically connected to the sensor chip 110, and receives, for example, an analog electrical signal from a bridge circuit that detects a moment My of rotation about the Y-axis output from the sensor chip 110, and an analog electrical signal from a bridge circuit that detects a moment Mz of rotation about the Z-axis output from the sensor chip 110. The active component 35 is, for example, a control IC that has the function of converting the analog electrical signal output from the sensor chip 110 into a digital electrical signal, internally performing temperature correction, amplitude correction, etc., and outputting the digital electrical signal.

[0020] Active component 32 is electrically connected to active components 33 to 35 and is a calculation IC that performs predetermined calculations on the digital electrical signals output by active components 33, 34, and 35, converts forces Fx, Fy, and Fz and moments Mx, My, and Mz into units of force or moment, and outputs the results externally. Active component 32 can output forces Fx, Fy, and Fz in units of [N] and moments Mx, My, and Mz in units of [N·cm], for example. Active component 32 may be a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). Passive components 39 are resistors, capacitors, etc. connected to active components 33 to 35.

[0021] Note that, when digitizing all six-axis outputs from the sensor chip 110 or when digitizing and performing correction calculations, etc., one control IC is typically required per axis. In this case, if mounting space for the control ICs is to be provided within the force sensor device 1, it is necessary to secure space for at least six of them, which would require an increase in the size of the force sensor device 1. While it is possible to achieve digitization of the output without increasing the size of the force sensor device 1 by connecting an external control board module with a mounted control IC, this is not desirable because it would increase the total occupied area and volume. It is also possible to integrate a control IC with the performance and functions of six axes into a single chip. However, even in this case, although the chip size would be smaller than the above-mentioned case in which six control ICs are used, it would still require an increase in the size of the force sensor device 1 if it were to be provided within the force sensor device 1.

[0022] Therefore, in this embodiment, three control ICs are used in a 2-in-1 package in which two chips are stacked and housed in one package. Because there is not much difference in size between a one-chip package and a 2-in-1 package, the control ICs can be placed on the side of the strain sensor 20. This makes it possible to mount control ICs for six axes within the force sensor device 1 without increasing the size of the force sensor device 1. In other words, it is possible to miniaturize the force sensor device 1, including the active components. Furthermore, it is possible to digitize the output signal of the sensor chip 110 without increasing the size of the force sensor device 1.

[0023] It is possible to arbitrarily determine how many ICs are used to realize the functions of the active components 32 to 35. It is also possible to arbitrarily determine how many ICs are mounted in the force sensor device 1. For example, it is also possible to mount only one control IC in the force sensor device 1.

[0024] The substrate 30 is bent outward below the first side surface of the strain generating body 20, and the other end of the substrate 30 is drawn out to the outside. On the other end of the substrate 30, input / output terminals (not shown) are arranged that enable electrical input and output to and from an external circuit (such as a control device) connected to the force sensor device 1.

[0025] In this way, by placing active components (such as a control IC) on the side of the strain-generating body 20, it is possible to realize a force sensor device 1 that can output digital signals that have been adjusted and corrected by the active components while minimizing the total size of the force sensor device 1.

[0026] Furthermore, by using a control IC in a 2-in-1 package, digital output becomes possible without increasing the size of the force sensor device 1.

[0027] Furthermore, since digital electrical signals are output from the substrate 30, noise resistance can be improved compared to when analog electrical signals are output.

[0028] In this embodiment, for convenience, the side of the force sensor device 1 on which the sensor chip 110 is provided is referred to as the upper side or one side, and the opposite side is referred to as the lower side or other side. Furthermore, the surface on which the sensor chip 110 of each portion is provided is referred to as one side or upper side, and the opposite side is referred to as the other side or lower side. However, the force sensor device 1 can be used upside down or placed at any angle. Furthermore, a planar view refers to viewing an object from the normal direction (Z-axis direction) of the top surface of the sensor chip 110, and a planar shape refers to the shape of the object viewed from the normal direction (Z-axis direction) of the top surface of the sensor chip 110.

[0029] (sensor chip 110) FIG. 4 is a diagram of the sensor chip 110 viewed from above in the Z-axis direction, with FIG. 4(a) being a perspective view and FIG. 4(b) being a plan view. FIG. 5 is a diagram of the sensor chip 110 viewed from below in the Z-axis direction, with FIG. 5(a) being a perspective view and FIG. 5(b) being a bottom view. In FIG. 5(b), for convenience, surfaces at the same height are shown with the same matte finish pattern. Note that the direction parallel to one side of the top surface of the sensor chip 110 is defined as the X-axis direction, the direction perpendicular to it is defined as the Y-axis direction, and the thickness direction of the sensor chip 110 (the normal direction to the top surface of the sensor chip 110) is defined as the Z-axis direction. The X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to one another.

[0030] 4 and 5 is a MEMS (Micro Electro Mechanical Systems) sensor chip capable of detecting up to six axes per chip, and is formed from a semiconductor substrate such as an SOI (Silicon On Insulator) substrate. The planar shape of the sensor chip 110 can be, for example, a square with sides of approximately 3000 μm.

[0031] The sensor chip 110 has five pillar-shaped support portions 111a to 111e. The planar shape of the support portions 111a to 111e can be, for example, a square with sides of about 500 μm. The support portions 111a to 111d, which are first support portions, are arranged at the four corners of the sensor chip 110. The support portion 111e, which is a second support portion, is arranged in the center of the support portions 111a to 111d.

[0032] The support portions 111a to 111e can be formed from, for example, an active layer, a BOX layer, and a support layer of an SOI substrate, and each can have a thickness of, for example, about 500 μm.

[0033] Between support portion 111a and support portion 111b, a reinforcing beam 112a is provided, with both ends fixed to support portion 111a and support portion 111b (connecting adjacent support portions), for reinforcing the structure. Between support portion 111b and support portion 111c, a reinforcing beam 112b is provided, with both ends fixed to support portion 111b and support portion 111c (connecting adjacent support portions), for reinforcing the structure.

[0034] Between support portion 111c and support portion 111d, a reinforcing beam 112c is provided, with both ends fixed to support portion 111c and support portion 111d (connecting adjacent support portions), for reinforcing the structure. Between support portion 111d and support portion 111a, a reinforcing beam 112d is provided, with both ends fixed to support portion 111d and support portion 111a (connecting adjacent support portions), for reinforcing the structure.

[0035] In other words, the four reinforcing beams 112a, 112b, 112c, and 112d that are the first reinforcing beams are formed in a frame shape, and the corners that form the intersections of the reinforcing beams become the support portions 111b, 111c, 111d, and 111a.

[0036] The inner corner of support portion 111a and the opposing corner of support portion 111e are connected by reinforcing beam 112e for structural reinforcement. The inner corner of support portion 111b and the opposing corner of support portion 111e are connected by reinforcing beam 112f for structural reinforcement.

[0037] An inner corner of support portion 111c and an opposing corner of support portion 111e are connected by a reinforcing beam 112g for reinforcing the structure. An inner corner of support portion 111d and an opposing corner of support portion 111e are connected by a reinforcing beam 112h for reinforcing the structure. Reinforcing beams 112e to 112h, which are second reinforcing beams, are arranged diagonally with respect to the X-axis direction (Y-axis direction). In other words, reinforcing beams 112e to 112h are arranged non-parallel to reinforcing beams 112a, 112b, 112c, and 112d.

[0038] The reinforcing beams 112a-112h can be formed, for example, from the active layer, BOX layer, and support layer of an SOI substrate. The thickness (width in the short direction) of the reinforcing beams 112a-112h can be, for example, about 140 μm. The upper surfaces of the reinforcing beams 112a-112h are approximately flush with the upper surfaces of the support portions 111a-111e.

[0039] In contrast, the lower surfaces of the reinforcing beams 112a to 112h are recessed upward by several tens of μm from the lower surfaces of the support portions 111a to 111e and the lower surfaces of the force points 114a to 114d. This is to prevent the lower surfaces of the reinforcing beams 112a to 112h from coming into contact with the opposing surface of the flexure element 20 when the sensor chip 110 is bonded to the flexure element 20.

[0040] In this way, by disposing reinforcing beams that are thicker and more rigid than the detection beams, in addition to the detection beams for detecting strain, it is possible to increase the rigidity of the entire sensor chip 110. This makes it difficult for parts other than the detection beams to deform in response to input, thereby achieving good sensor characteristics.

[0041] A detection beam 113a for detecting strain is provided inside the reinforcing beam 112a between the support portions 111a and 111b, parallel to the reinforcing beam 112a at a predetermined distance, and has both ends fixed to the support portions 111a and 111b (connecting adjacent support portions).

[0042] A detection beam 113b is provided between the detection beam 113a and the support portion 111e at a predetermined distance from the detection beam 113a and the support portion 111e and parallel to the detection beam 113a. The detection beam 113b connects the end of the reinforcing beam 112e on the support portion 111e side to the end of the reinforcing beam 112f on the support portion 111e side.

[0043] The approximate center of the longitudinal direction of detection beam 113a and the approximate center of the longitudinal direction of the opposing detection beam 113b are connected by detection beam 113c, which is arranged perpendicular to detection beam 113a and detection beam 113b.

[0044] A detection beam 113d for detecting strain is provided inside the reinforcing beam 112b between the support portions 111b and 111c, parallel to the reinforcing beam 112b at a predetermined distance, and has both ends fixed to the support portions 111b and 111c (connecting adjacent support portions).

[0045] A detection beam 113e is provided between the detection beam 113d and the support portion 111e at a predetermined distance from the detection beam 113d and the support portion 111e, and parallel to the detection beam 113d. The detection beam 113e connects the end of the reinforcing beam 112f on the support portion 111e side and the end of the reinforcing beam 112g on the support portion 111e side.

[0046] The approximate center of the longitudinal direction of detection beam 113d and the approximate center of the longitudinal direction of the opposing detection beam 113e are connected by detection beam 113f, which is arranged perpendicular to detection beam 113d and detection beam 113e.

[0047] A detection beam 113g for detecting distortion is provided inside the reinforcing beam 112c between the support portions 111c and 111d, parallel to the reinforcing beam 112c at a predetermined distance, and has both ends fixed to the support portions 111c and 111d (connecting adjacent support portions).

[0048] A detection beam 113h is provided between the detection beam 113g and the support portion 111e at a predetermined distance from the detection beam 113g and the support portion 111e and parallel to the detection beam 113g. The detection beam 113h connects the end of the reinforcing beam 112g on the support portion 111e side to the end of the reinforcing beam 112h on the support portion 111e side.

[0049] The approximate center of the longitudinal direction of the detection beam 113g and the approximate center of the longitudinal direction of the opposite detection beam 113h are connected by a detection beam 113i that is arranged perpendicular to the detection beam 113g and the detection beam 113h.

[0050] A detection beam 113j for detecting strain is provided inside the reinforcing beam 112d between the support portion 111d and the support portion 111a, parallel to the reinforcing beam 112d at a predetermined distance, and has both ends fixed to the support portion 111d and the support portion 111a (connecting adjacent support portions).

[0051] A detection beam 113k is provided between the detection beam 113j and the support portion 111e at a predetermined distance from the detection beam 113j and the support portion 111e and parallel to the detection beam 113j. The detection beam 113k connects the end of the reinforcing beam 112h on the support portion 111e side to the end of the reinforcing beam 112e on the support portion 111e side.

[0052] The approximate center of the longitudinal direction of the detection beam 113j and the approximate center of the longitudinal direction of the opposite detection beam 113k are connected by a detection beam 113l that is arranged perpendicular to the detection beam 113j and the detection beam 113k.

[0053] The detection beams 113a to 113l are provided on the upper end sides of the support portions 111a to 111e in the thickness direction, and can be formed, for example, from the active layer of an SOI substrate. The thickness (width in the short direction) of the detection beams 113a to 113l can be, for example, about 75 μm. The upper surfaces of the detection beams 113a to 113l are substantially flush with the upper surfaces of the support portions 111a to 111e. The thickness of the detection beams 113a to 113l can be, for example, about 50 μm.

[0054] A force point 114a is provided on the lower surface side of the longitudinal center portion of the detection beam 113a (the intersection of the detection beam 113a and the detection beam 113c). The detection beams 113a, 113b, and 113c and the force point 114a form a set of detection blocks.

[0055] A force point 114b is provided on the lower surface side of the longitudinal center portion of the detection beam 113d (the intersection of the detection beam 113d and the detection beam 113f). The detection beams 113d, 113e, and 113f and the force point 114b form a set of detection blocks.

[0056] A force point 114c is provided on the lower surface side of the longitudinal center portion of the detection beam 113g (the intersection of the detection beam 113g and the detection beam 113i). The detection beams 113g, 113h, and 113i and the force point 114c form a set of detection blocks.

[0057] A force point 114d is provided on the lower surface side of the longitudinal center portion of the detection beam 113j (the intersection of the detection beam 113j and the detection beam 113l). The detection beams 113j, 113k, and 113l and the force point 114d form one detection block.

[0058] The force points 114a to 114d are locations where an external force is applied, and can be formed from, for example, the BOX layer and support layer of an SOI substrate. The lower surfaces of the force points 114a to 114d are approximately flush with the lower surfaces of the support portions 111a to 111e.

[0059] In this way, by applying force or displacement from the four force points 114a to 114d, different beam deformations can be obtained for each type of force, making it possible to realize a sensor with good six-axis separation.

[0060] In the sensor chip 110, from the viewpoint of suppressing stress concentration, it is preferable that the portions forming the interior angles are rounded.

[0061] 6 is a diagram illustrating an example of the arrangement of piezoresistance elements on the sensor chip 110. A plurality of piezoresistance elements, which are strain sensing elements, are arranged at predetermined positions on each sensing block corresponding to the four force points 114a to 114d.

[0062] 4 and 6, in the detection block corresponding to the force point 114a, the piezoresistive elements MxR3 and MxR4 are arranged on a line that bisects the detection beam 113a in the longitudinal direction and at positions symmetrical with respect to the line that bisects the detection beam 113c in the longitudinal direction (Y direction) in a region of the detection beam 113a close to the detection beam 113c. The piezoresistive elements FyR3 and FyR4 are arranged closer to the reinforcing beam 112a than the line that bisects the detection beam 113a in the longitudinal direction and at positions symmetrical with respect to the line that bisects the detection beam 113c in the longitudinal direction in a region of the detection beam 113a farther from the detection beam 113c.

[0063] Furthermore, the piezoresistance elements MzR3' and MzR4' are located on a line that bisects the detection beam 113a in the longitudinal direction, and are positioned symmetrically with respect to the line that bisects the detection beam 113c in the longitudinal direction near the midpoint between the position where the detection beam 113a is connected to the support portions 111a and 111b and the position where the detection beam 113a is connected to the force point 114a.

[0064] Here, the width of the detection beam 113a at the position where the piezoresistive elements MzR3' and MzR4' are formed is smaller than the width of the detection beam 113a at the position where it is connected to the support portions 111a and 111b or the force point 114a. The detection beam 113a has a portion where the beam width is narrowed between the position where it is connected to the support portions 111a and 111b and the position where it is connected to the force point 114a, and the piezoresistive elements MzR3' and MzR4' are formed on the detection beam 113a at this portion where the beam width is narrowed.

[0065] In the detection block corresponding to the force point 114b, the piezoresistive elements MyR3 and MyR4 are arranged on a line that bisects the detection beam 113d in the longitudinal direction and at positions symmetrical with respect to the line that bisects the detection beam 113f in the longitudinal direction (X direction) in a region of the detection beam 113d close to the detection beam 113f. The piezoresistive elements FxR3 and FxR4 are arranged closer to the reinforcing beam 112b than the line that bisects the detection beam 113d in the longitudinal direction and at positions symmetrical with respect to the line that bisects the detection beam 113f in the longitudinal direction in a region of the detection beam 113d farther from the detection beam 113f.

[0066] Furthermore, the piezoresistance elements MzR3 and MzR4 are arranged on a line that bisects the detection beam 113d in the longitudinal direction, and at a position symmetrical with respect to the line that bisects the detection beam 113f in the longitudinal direction near the midpoint between the position where the detection beam 113d is connected to the support portions 111b, 111c and the position where the detection beam 113d is connected to the force point 114b.

[0067] Here, the width of the detection beam 113d at the position where the piezoresistive elements MzR3 and MzR4 are formed is smaller than the width of the detection beam 113d at the position where it is connected to the supports 111b, 111c or the force point 114b. The detection beam 113d has a portion where the beam width is narrowed between the position where it is connected to the supports 111b, 111c and the position where it is connected to the force point 114b, and the piezoresistive elements MzR3 and MzR4 are formed on the detection beam 113d at this portion where the beam width is narrowed.

[0068] The piezoresistive elements FzR2 and FzR3 are arranged on a line that bisects the detection beam 113e in the longitudinal direction, and at positions symmetrical with respect to the line that bisects the detection beam 113f in the longitudinal direction in a region of the detection beam 113e close to the detection beam 113f. The piezoresistive elements FzR1' and FzR4' are arranged on a line that bisects the detection beam 113e in the longitudinal direction, and at positions symmetrical with respect to the line that bisects the detection beam 113f in the longitudinal direction in a region of the detection beam 113e far from the detection beam 113f.

[0069] Here, the detection beam 113e has a straight portion and an inclined portion connected to the straight portion by a connecting portion. The straight portion is a portion of the detection beam 113e where the beam width is approximately constant. The inclined portion is a portion provided at the end of the detection beam 113e or at the portion connecting to the detection beam 113f, and the beam width of the inclined portion gradually increases with increasing distance from the connecting portion. In the detection beam 113e configured as described above, the piezo-resistance elements FzR2, FzR3, FzR1', and FzR4' are arranged on the inclined portion side of the connecting portion.

[0070] That is, the piezoresistors FzR2, FzR3, FzR1', and FzR4' are disposed inside the inclined portion, not on the straight portion, of the detection beam 113e. Also, the piezoresistors FzR1' and FzR4' are formed so that a portion of each of the piezoresistors FzR1' and FzR4' overlaps the reinforcing beam 112g or the reinforcing beam 112f.

[0071] In the detection block corresponding to the force point 114c, the piezoresistive elements MxR1 and MxR2 are arranged on a line that bisects the detection beam 113g in the longitudinal direction and at positions symmetrical with respect to the line that bisects the detection beam 113i in the longitudinal direction (Y direction) in a region of the detection beam 113g close to the detection beam 113i. The piezoresistive elements FyR1 and FyR2 are arranged closer to the reinforcing beam 112c than the line that bisects the detection beam 113g in the longitudinal direction and at positions symmetrical with respect to the line that bisects the detection beam 113i in the longitudinal direction in a region of the detection beam 113g farther from the detection beam 113i.

[0072] The piezoresistance elements MzR1' and MzR2' are located on a line that bisects the detection beam 113g in the longitudinal direction, and are positioned symmetrically with respect to the line that bisects the detection beam 113i in the longitudinal direction near the midpoint between the position where the detection beam 113g is connected to the support portions 111c, 111d and the position where the detection beam 113g is connected to the force point 114c.

[0073] Here, the width of the detection beam 113g at the position where the piezoresistance elements MzR1' and MzR2' are formed is smaller than the width of the detection beam 113g at the position where it is connected to the support portions 111c, 111d or the force point 114c.

[0074] That is, the detection beam 113g has a portion where the beam width is narrowed between the position where it is connected to the support portions 111c and 111d and the position where it is connected to the force point 114c, and piezoresistance elements MzR1' and MzR2' are formed on the detection beam 113g at this portion where the beam width is narrowed.

[0075] In the detection block corresponding to the force point 114d, the piezoresistive elements MyR1 and MyR2 are arranged on a line that bisects the detection beam 113j in the longitudinal direction and at positions symmetrical with respect to the line that bisects the detection beam 113l in the longitudinal direction (X direction) in a region of the detection beam 113j close to the detection beam 113l. The piezoresistive elements FxR1 and FxR2 are arranged closer to the reinforcing beam 112d than the line that bisects the detection beam 113j in the longitudinal direction and at positions symmetrical with respect to the line that bisects the detection beam 113l in the longitudinal direction in a region of the detection beam 113j farther from the detection beam 113l.

[0076] The piezoresistive elements MzR1 and MzR2 are located on a line that bisects the detection beam 113j in the longitudinal direction, and are positioned symmetrically with respect to the line that bisects the detection beam 113l in the longitudinal direction near the midpoint between the position where the detection beam 113j is connected to the support portions 111d, 111a and the position where the detection beam 113j is connected to the force point 114d.

[0077] Here, the width of the detection beam 113j at the position where the piezoresistance elements MzR1 and MzR2 are formed is smaller than the width of the detection beam 113j at the position where it is connected to the support portions 111d, 111a or the force point 114d.

[0078] That is, the detection beam 113j has a portion where the beam width is narrowed between the position where it is connected to the support portions 111d and 111a and the position where it is connected to the force point 114d, and piezoresistance elements MzR1 and MzR2 are formed on the detection beam 113j at this portion where the beam width is narrowed.

[0079] The piezoresistive elements FzR1 and FzR4 are arranged on a line that bisects the detection beam 113k in the longitudinal direction, and at positions symmetrical with respect to the line that bisects the detection beam 113l in the longitudinal direction in a region of the detection beam 113k far from the detection beam 113l. The piezoresistive elements FzR2' and FzR3' are arranged on a line that bisects the detection beam 113k in the longitudinal direction, and at positions symmetrical with respect to the line that bisects the detection beam 113l in the longitudinal direction in a region of the detection beam 113k close to the detection beam 113l.

[0080] Here, the detection beam 113k has a straight portion and an inclined portion connected to the straight portion by a connecting portion. The straight portion is a portion of the detection beam 113k where the beam width is approximately constant. The inclined portion is a portion provided at the end of the detection beam 113k or at the portion connected to the detection beam 113l, and the beam width of the inclined portion gradually increases with increasing distance from the connecting portion. In the detection beam 113k configured as described above, the piezo-resistance elements FzR1, FzR4, FzR2', and FzR3' are arranged on the inclined portion side from the connecting portion.

[0081] That is, the piezoresistive elements FzR1, FzR4, FzR2', and FzR3' are disposed inside the inclined portion, not on the straight portion, of the detection beam 113k. Also, the piezoresistive elements FzR1 and FzR4 are formed so that a portion of each of the piezoresistive elements FzR1 and FzR4 overlaps the reinforcing beam 112h or the reinforcing beam 112e.

[0082] In this way, multiple piezoresistor elements are arranged separately in each detection block in the sensor chip 110. This makes it possible to detect displacement in a predetermined axial direction along up to six axes based on changes in output from multiple piezoresistor elements arranged on a predetermined beam according to the direction (axial direction) of force applied (transmitted) to the force points 114a to 114d.

[0083] Furthermore, in the sensor chip 110, the detection beams 113c, 113f, 113i, and 113l are made as short as possible, and the detection beams 113b, 113e, 113h, and 113k are brought close to the detection beams 113a, 113d, 113g, and 113j, thereby ensuring the lengths of the detection beams 113b, 113e, 113h, and 113k as much as possible. This structure makes it easier for the detection beams 113b, 113e, 113h, and 113k to bend in a bow shape, which alleviates stress concentration and improves load resistance.

[0084] Furthermore, in the sensor chip 110, piezoresistor elements are not arranged on the detection beams 113c, 113f, 113i, and 113l. Instead, piezoresistor elements are arranged near the positions where the stress is maximum on the detection beams 113a, 113d, 113g, and 113j, and the detection beams 113b, 113e, 113h, and 113k, which are thinner and longer than the detection beams 113c, 113f, 113i, and 113l and more likely to bend like a bow. As a result, the sensor chip 110 can efficiently take in stress, thereby improving sensitivity (the change in resistance of the piezoresistor element for the same stress).

[0085] In addition to the piezoresistance elements used for detecting strain, dummy piezoresistance elements are also arranged on the sensor chip 110. The dummy piezoresistance elements are arranged so that all the piezoresistance elements, including the piezoresistance elements used for detecting strain, are point-symmetric with respect to the center of the support portion 111e.

[0086] Here, piezoresistor elements FxR1 to FxR4 detect force Fx, piezoresistor elements FyR1 to FyR4 detect force Fy, and piezoresistor elements FzR1 to FzR4 and FzR1' to FzR4' detect force Fz. piezoresistor elements MxR1 to MxR4 detect moment Mx, piezoresistor elements MyR1 to MyR4 detect moment My, and piezoresistor elements MzR1 to MzR4 and MzR1' to MzR4' detect moment Mz. In this embodiment, piezoresistor elements FzR1' to FzR4' may be used as dummy elements, and force Fz may be detected from piezoresistor elements FzR1 to FzR4. Also, piezoresistor elements MzR1' to MzR4' may be used as dummy elements, and moment Mz may be detected from piezoresistor elements MzR1 to MzR4.

[0087] In this way, multiple piezoresistor elements are arranged separately in each detection block in the sensor chip 110. This makes it possible to detect displacement in a predetermined axial direction along up to six axes based on changes in output from multiple piezoresistor elements arranged on a predetermined beam according to the direction (axial direction) of the force or displacement applied (transmitted) to the force points 114a to 114d.

[0088] Specifically, in the sensor chip 110, displacements (Mx, My, Fz) in the Z-axis direction can be detected based on the deformation of predetermined detection beams. That is, moments (Mx, My) in the X-axis direction and Y-axis direction can be detected based on the deformation of detection beams 113a, 113d, 113g, and 113j, which are first detection beams. Furthermore, force (Fz) in the Z-axis direction can be detected based on the deformation of detection beams 113e and 113k, which are second detection beams.

[0089] Furthermore, in the sensor chip 110, displacements (Fx, Fy, Mz) in the X-axis direction and the Y-axis direction can be detected based on the deformation of predetermined detection beams. That is, forces (Fx, Fy) in the X-axis direction and the Y-axis direction can be detected based on the deformation of detection beams 113a, 113d, 113g, and 113j, which are first detection beams. Furthermore, moment (Mz) in the Z-axis direction can be detected based on the deformation of detection beams 113a, 113d, 113g, and 113j, which are first detection beams.

[0090] In the sensor chip of the present embodiment, the detection beam 113e has a straight portion and an inclined portion connected to the straight portion by a connecting portion, and the piezoresistors FzR2, FzR3, FzR1', and FzR4' are arranged on the inclined portion side of the connecting portion in the detection beam 113e having the above configuration. Also, the detection beam 113k has a straight portion and an inclined portion connected to the straight portion by a connecting portion, and the piezoresistors FzR1, FzR4, FzR2', and FzR3' are arranged on the inclined portion side of the connecting portion in the detection beam 113k having the above configuration.

[0091] By varying the thickness and width of each detection beam, it is possible to make adjustments such as making the detection sensitivity uniform or improving the detection sensitivity.

[0092] However, it is also possible to reduce the number of piezoresistance elements and create a sensor chip that detects displacement in five or fewer predetermined axial directions.

[0093] 7 is a diagram illustrating an example of electrode arrangement and wiring in the sensor chip 110, and is a plan view of the sensor chip 110 viewed from above in the Z-axis direction. As shown in FIG. 7, the sensor chip 110 has a plurality of electrodes 15 for extracting electrical signals. Each electrode 15 is arranged on the upper surface of the support portions 111a to 111d of the sensor chip 110, where distortion is minimal when force is applied to the force points 114a to 114d. Wiring 16 from each piezoresistance element to the electrode 15 can be routed appropriately over each reinforcing beam and each detection beam.

[0094] In this way, each reinforcing beam can be used as a detour when pulling out wiring as needed, so by arranging the reinforcing beams separately from the detection beams, the degree of freedom in wiring design can be improved, and each piezo-resistive element can be placed in a more ideal position.

[0095] Fig. 8 is an enlarged plan view illustrating the temperature sensor of the sensor chip 110. As shown in Fig. 7 and Fig. 8, the sensor chip 110 includes a temperature sensor 17 for performing temperature compensation on the piezoresistance elements used for strain detection. The temperature sensor 17 has a bridge-connected configuration of four piezoresistance elements TR1, TR2, TR3, and TR4.

[0096] Of the piezoresistor elements TR1, TR2, TR3, and TR4, two opposing elements have the same characteristics as the piezoresistor elements MxR1, etc. used for strain detection. In addition, the other two opposing elements of the piezoresistor elements TR1, TR2, TR3, and TR4 have different characteristics from the piezoresistor elements MxR1, etc. by changing the impurity concentration using an impurity semiconductor. This causes the bridge to lose balance due to temperature changes, making it possible to detect temperature.

[0097] All of the piezoresistance elements (MxR1, etc.) used for strain detection are arranged horizontally or vertically to the crystal orientation of the semiconductor substrate (silicon, etc.) that constitutes the sensor chip 110. This allows a larger change in resistance to be obtained for the same strain, making it possible to improve the measurement accuracy of applied forces and moments.

[0098] In contrast, the piezoresistance elements TR1, TR2, TR3, and TR4 that make up the temperature sensor 17 are arranged at an angle of 45 degrees with respect to the crystal orientation of the semiconductor substrate (silicon or the like) that makes up the sensor chip 110. This reduces resistance changes due to stress, allowing only temperature changes to be detected with high accuracy.

[0099] Furthermore, the temperature sensor 17 is disposed on the upper surface of the support portion 111a of the sensor chip 110, where distortion is minimal when force is applied to the force points 114a to 114d. This further reduces resistance changes due to stress.

[0100] The piezoresistance element is a typical example of the strain detection element according to the present invention.

[0101] (Strain body 20) FIG. 9 is a diagram (part 1) illustrating the flexure body 20, with FIG. 9(a) being a perspective view and FIG. 9(b) being a side view. FIG. 10 is a diagram (part 2) illustrating the flexure body 20, with FIG. 10(a) being a plan view and FIG. 10(b) being a perspective vertical cross-sectional view taken along line AA in FIG. 10(a). In FIG. 10(a), for convenience, surfaces at the same height are shown with the same matte finish pattern. FIG. 11 is a diagram (part 3) illustrating the flexure body 20, with FIG. 11(a) being a vertical cross-sectional view taken along line BB in FIG. 10(a) and FIG. 11(b) being a horizontal cross-sectional view taken along line CC in FIG. 11(a).

[0102] As shown in Figures 9 to 11, the strain-generating body 20 includes a base 21 that is directly attached to the fixed portion, a pillar 28 that serves as a sensor chip mounting portion on which the sensor chip 110 is mounted, and pillars 22a to 22d that are arranged around the pillar 28 at a distance.

[0103] More specifically, in the flexure body 20, four pillars 22a to 22d are arranged on the upper surface of a substantially circular base 21 so as to be evenly spaced (point symmetric) about the center of the base 21, and beams 23a to 23d are provided in a frame shape to connect adjacent pillars on the opposite side of the base 21. A pillar 28 is arranged above the center of the upper surface of the base 21. The planar shape of the base 21 is not limited to a circle, and may be a polygon (for example, a square), etc.

[0104] The pillar 28 is formed to be thicker and shorter than the pillars 22a to 22d. The sensor chip 110 is fixed on the pillar 28 so as not to protrude from the upper surfaces of the pillars 22a to 22d.

[0105] Pillar 28 is not fixed directly to the upper surface of base 21, but is fixed to pillars 22a to 22d via connecting beams 28a to 28d. Therefore, there is a space between the upper surface of base 21 and the lower surface of pillar 28. The lower surface of pillar 28 and the lower surfaces of each of connecting beams 28a to 28d can be flush with each other.

[0106] The cross-sectional shape of the portion of the pillar 28 where the connecting beams 28a-28d are connected is, for example, rectangular, and the four corners of the rectangle are connected to the pillars 22a-22d facing the four corners of the rectangle via the connecting beams 28a-28d. It is preferable that the positions 221-224 where the connecting beams 28a-28d are connected to the pillars 22a-22d are lower than the middle in the height direction of the pillars 22a-22d. The reason for this will be described later. Note that the cross-sectional shape of the portion of the pillar 28 where the connecting beams 28a-28d are connected is not limited to a rectangle, and may be a circle, a polygon (for example, a hexagon), or the like.

[0107] The connecting beams 28a to 28d are arranged substantially parallel to the upper surface of the base 21 at a predetermined distance from the upper surface of the base 21 so as to be uniform (point symmetric) about the center of the base 21. The width and thickness (rigidity) of the connecting beams 28a to 28d are preferably formed to be thinner and narrower than the columns 22a to 22d and the beams 23a to 23d so as not to hinder the deformation of the strain-generating body 20.

[0108] In this way, the upper surface of the base 21 and the lower surface of the pillar 28 are spaced a predetermined distance apart. The predetermined distance can be, for example, about several millimeters. In a structure in which the pillar 28 is not directly fixed to the upper surface of the base 21 but is fixed to the pillars 22a to 22d via the connecting beams 28a to 28d, the longer the distance between the upper surface of the base 21 and the lower surface of the pillar 28, the less deformation of the pillar 28 occurs when the screws are fastened, and as a result, the Fz output (offset) of the sensor chip 110 is reduced. On the other hand, the longer the distance between the upper surface of the base 21 and the lower surface of the pillar 28, the lower the output of the sensor chip 110 (the lower the sensitivity).

[0109] That is, it is preferable to connect the pillar 28 below the midpoint between the pillars 22a to 22d. This ensures the sensitivity of the sensor chip 110 while reducing the Fz output (offset) of the sensor chip 110 when fastened with the screws.

[0110] If an attempt were made to reduce the Fz output (offset) of the sensor chip 110 when the screws are tightened by increasing the rigidity of the base 21, it would be necessary to increase the thickness of the base 21, which would increase the size of the entire force sensor device. By using a structure in which the pillars 28 are not fixed directly to the upper surface of the base 21 but are fixed to the pillars 22a to 22d via the connecting beams 28a to 28d, the Fz output (offset) of the sensor chip 110 when the screws are tightened can be reduced without increasing the size of the entire force sensor device.

[0111] Furthermore, by fixing the pillars 28 not directly to the upper surface of the base 21 but to the pillars 22a to 22d via the connecting beams 28a to 28d, it is possible to improve the separation of the moment components (Mx, My) and the translational force components (Fx, Fy) when a moment (Mx, My) is input.

[0112] The base 21 is provided with through holes 21x for fastening the strain body 20 to a fixed portion using screws or the like. In this embodiment, the base 21 is provided with four through holes 21x, but the number of through holes 21x can be determined arbitrarily.

[0113] The general shape of the flexure element 20 excluding the base 21 can be, for example, a rectangular parallelepiped with a length of about 5000 μm, a width of about 5000 μm, and a height of about 7000 μm. The cross-sectional shape of the pillars 22a to 22d can be, for example, a square with sides of about 1000 μm. The cross-sectional shape of the pillar 28 can be, for example, a square with sides of about 2000 μm.

[0114] However, in order to suppress stress concentration in the flexure element 20, it is preferable that the portions forming the interior angles are rounded. For example, it is preferable that the top and bottom of the surfaces of the columns 22a to 22d on the center side of the upper surface of the base 21 are rounded. Similarly, it is preferable that the surfaces of the beams 23a to 23d facing the upper surface of the base 21 are rounded on the left and right.

[0115] The larger the radius of curvature of the R-shaped portion, the greater the effect of suppressing stress concentration. However, if the radius of curvature of the R-shaped portion is made too large, the strain element 20 becomes large, and as a result, the force sensor device 1 also becomes large, so there is a limit to how large the radius of curvature of the R-shaped portion can be made.

[0116] 10(a), the beams 23a to 23d are thicker at their longitudinal center portions than at their both ends, where excessive stress concentration occurs when Mx, My, and Mz are applied to the force sensor device 1. The longitudinal center portions of the beams 23a to 23d are provided with protruding portions that protrude inward and outward beyond the side surfaces of the pillars 22a to 22d.

[0117] This increases the cross-sectional area of ​​the longitudinal central portions of the beams 23a to 23d, thereby reducing the stress that occurs in the longitudinal central portions of the beams 23a to 23d where stress was originally concentrated when Mx, My, and Mz are applied to the force sensor device 1. In other words, it is possible to alleviate the stress concentration in the longitudinal central portions of the beams 23a to 23d.

[0118] Furthermore, by providing protruding portions by causing the side surfaces of the longitudinal center portions of the beams 23a to 23d to protrude outward beyond the side surfaces of the columns 22a to 22d, excess space is generated on the four side surfaces of the strain-generating body 20, and therefore at least a portion of each of the active components 32 to 35 can fit into the excess space, allowing them to be efficiently arranged on the side surfaces of the strain-generating body 20 (see Figures 1, 2, etc.).

[0119] The active components 32 to 35 can be arranged, for example, on the side of the strain generating body 20 closer to the base 21 than the beams 23a to 23d so that they at least partially overlap with the protruding portion in a plan view (see Figures 2(a), 2(b), etc.).

[0120] Input portions 24a to 24d are provided at the longitudinal center of the upper surface of each of the beams 23a to 23d, protruding upward from the longitudinal center of the beams 23a to 23d. The input portions 24a to 24d are, for example, rectangular, but may also be circular, elliptical, or other more complex shapes. The input portions 24a to 24d are portions to which an external force is applied, and when a force is applied to the input portions 24a to 24d, the beams 23a to 23d and the columns 22a to 22d deform accordingly.

[0121] By providing four input portions 24a to 24d in this way, the load resistance of beams 23a to 23d can be improved compared to a structure with one input portion, for example.

[0122] Four pillars 25a to 25d are arranged at the four corners of the top surface of pillar 28, and a fourth pillar 25e is arranged in the center of the top surface of pillar 28. Pillars 25a to 25e are formed to be the same height.

[0123] That is, the upper surfaces of the pillars 25a to 25e are located on the same plane. The upper surfaces of the pillars 25a to 25e form joints that are bonded to the lower surface of the sensor chip 110.

[0124] Beams 26a to 26d are provided at the longitudinal center of each inner surface of beams 23a to 23d, protruding horizontally inward from the inner surface of each beam 23a to 23d. Beams 26a to 26d transmit deformation of beams 23a to 23d and columns 22a to 22d to sensor chip 110. Furthermore, protrusions 27a to 27d are provided at the tip end of the upper surface of each beam 26a to 26d, protruding upward from the tip end of the upper surface of each beam 26a to 26d.

[0125] The protrusions 27a to 27d are formed at the same height. That is, the upper surfaces of the protrusions 27a to 27d are located on the same plane. The upper surfaces of the protrusions 27a to 27d serve as joints that are bonded to the lower surface of the sensor chip 110. The beams 26a to 26d and the protrusions 27a to 27d are connected to the beams 23a to 23d that serve as movable parts, and therefore, when a force is applied to the input parts 24a to 24d, they deform accordingly.

[0126] When no force is applied to the input portions 24a to 24d, the upper surfaces of the pillars 25a to 25e and the upper surfaces of the protrusions 27a to 27d are located on the same plane.

[0127] In the flexure element 20, the base 21, pillars 22a-22d, pillar 28, beams 23a-23d, input portions 24a-24d, pillars 25a-25e, beams 26a-26d, and protrusions 27a-27d are preferably integrally formed from the viewpoint of ensuring rigidity and fabricating with high precision. The material of the flexure element 20 may be, for example, a hard metal material such as SUS (stainless steel). Among these, it is preferable to use SUS630, which is particularly hard and has high mechanical strength.

[0128] In this way, by making the strain-generating body 20 have a structure with pillars and beams, similar to the sensor chip 110, it shows different deformations in each of the six axes depending on the applied force, and therefore deformations with good separation in the six axes can be transmitted to the sensor chip 110.

[0129] That is, the force applied to the input portions 24a to 24d of the strain-generating body 20 is transmitted to the sensor chip 110 via the pillars 22a to 22d, the beams 23a to 23d, and the beams 26a to 26d, and the displacement is detected by the sensor chip 110. Then, in the sensor chip 110, an output for each axis can be obtained from a bridge circuit formed one for each axis.

[0130] (Manufacturing process of the force sensor device 1) 12 to 15 are diagrams illustrating an example of a manufacturing process for the force sensor device 1. First, in the process shown in FIG. 12, adhesive 41 is applied to the upper surfaces of the pillars 25a to 25e and the upper surfaces of the protrusions 27a to 27d of the flexure body 20. Then, the sensor chip 110 is placed within the flexure body 20 while being pressed so that the lower surface of the sensor chip 110 contacts the adhesive 41 applied to the upper surfaces of the pillars 25a to 25e and the upper surfaces of the protrusions 27a to 27d. The adhesive 41 is then heated to a predetermined temperature and cured. This fixes the sensor chip 110 within the flexure body 20. Specifically, the support portions 111a to 111d of the sensor chip 110 are fixed onto the pillars 25a to 25e, respectively, the support portion 111e is fixed onto the pillar 25e, and the force points 114a to 114d are fixed onto the protrusions 27a to 27d, respectively.

[0131] The flexure element 20 can be formed as a single unit by, for example, molding, cutting, wire discharge, or the like. As the material for the flexure element 20, for example, a hard metal material such as SUS (stainless steel) can be used. Among these, it is preferable to use SUS630, which is particularly hard and has high mechanical strength. When producing the flexure element 20 by molding, for example, metal particles and a resin that serves as a binder are placed in a mold and molded, and then sintered to evaporate the resin, thereby producing the flexure element 20 made of metal.

[0132] For example, an adhesive such as modified silicone can be used as the adhesive 41. The Young's modulus of the adhesive 41 is preferably 130 MPa or more and 1.5 GPa or less, and the thickness of the adhesive 41 is preferably 10 μm or more and 40 μm or less.

[0133] The sensor chip 110 can be fabricated by a well-known method, for example, by preparing an SOI substrate and subjecting the prepared substrate to etching (e.g., reactive ion etching, etc.) etc. The electrodes and wiring can be fabricated by, for example, forming a metal film such as aluminum on the surface of the substrate by sputtering, etc., and then patterning the metal film by photolithography.

[0134] Next, in the step shown in Fig. 13, a substrate 30 on which active components 32 to 35 and passive components 39 are mounted is prepared. The substrate 30 has end surface fixing portions 30a that are fixed to the upper surfaces (end surfaces) of the pillars 22a to 22d. In Fig. 13, the crossed areas are the end surface fixing portions 30a. Electrodes 31 (bonding pads) are provided at the four corners of the end surface fixing portion 30a.

[0135] The substrate 30 has side surface fixing portions 30b to 30e that extend in four directions from the end surface fixing portion 30a and are bent relative to the end surface fixing portion 30a in the step of FIG. 15(a) and fixed to the side surfaces of the pillars 22a to 22d.

[0136] In this embodiment, active component 32 is mounted on side surface fixing portion 30b, active component 33 and passive component 39 are mounted on side surface fixing portion 30c, active component 34 and passive component 39 are mounted on side surface fixing portion 30d, and active component 35 and passive component 39 are mounted on side surface fixing portion 30e. However, it is not necessary for active components to be mounted on all of side surface fixing portions 30b to 30e, as long as an active component is mounted on at least one of side surface fixing portions 30b to 30e.

[0137] The substrate 30 has an extension portion 30f extending from the side fixing portion 30b. Input / output terminals (not shown) that can electrically input and output data to and from an external circuit (such as a control device) connected to the force sensor device 1 are arranged at the end of the extension portion 30f.

[0138] The end surface fixing portion 30a has openings 30x that expose the sensor chip 110 and the input portions 24a to 24d when it is fixed to the upper surfaces (end surfaces) of the pillars 22a to 22d in the step of Fig. 14(a). The openings 30x extend from the end surface fixing portion 30a to a portion of each of the side surface fixing portions 30b to 30e.

[0139] In this way, the substrate 30 can have, for example, a cross-shaped outer shape because it has the opening 30x, allows for easy routing of wiring, and has the active components 32 to 35 mounted thereon.

[0140] After preparing the substrate 30 as described above, adhesive 42 is applied to the upper surfaces of the pillars 22a to 22d. For example, an epoxy adhesive or the like can be used as the adhesive 42. Note that the adhesive 42 is used to fix the substrate 30 onto the strain-generating body 20, and since no external force is applied to it, a general-purpose adhesive can be used.

[0141] 14(a), the substrate 30 is placed on the strain generating body 20 so that the lower surfaces of the four corners of the end face fixing portion 30a of the substrate 30 come into contact with the adhesive 42 applied to the upper surfaces of the pillars 22a to 22d. At this point, the side face fixing portions 30b to 30e are not bent relative to the end face fixing portion 30a.

[0142] 14(b), adhesive 43 is applied to the two outward-facing side surfaces of each of the pillars 22a to 22d (for example, two locations on each of the top and bottom). However, in the region where the active components 32 are mounted and bonded to the bottom surface of the substrate 30, adhesive 43 is applied so as to extend from the lower side surfaces of the pillars 22a and 22d to the outer periphery of the top surface of the base 21.

[0143] As the adhesive 43, for example, an epoxy-based adhesive or the like can be used. Note that the adhesive 43 is used to fix the substrate 30 onto the flexure element 20, and since no external force is applied, a general-purpose adhesive can be used. The same adhesive as the adhesive 42 may be used as the adhesive 43. Alternatively, a relatively hard adhesive (high Young's modulus) containing filler may be used as the adhesive 42 to ensure wire bonding properties, and a relatively soft adhesive (low Young's modulus) may be used as the adhesive 43 to ensure flexibility to follow the deformation of the flexure element 20. Furthermore, the adhesive 43 may be applied together with the adhesive 42 in the step of FIG. 13.

[0144] 15(a), the side surface fixing portions 30b to 30e that protrude horizontally from the end surface fixing portion 30a arranged on the flexure element 20 are bent toward each side surface of the flexure element 20. Then, while pressing the substrate 30 toward the flexure element 20, the adhesives 42 and 43 are heated to a predetermined temperature and hardened. This fixes the substrate 30 to the flexure element 20. Note that the substrate 30 is a flexible substrate and is sufficiently soft relative to the flexure element 20, and the substrate 30 and the flexure element 20 are only partially bonded together, so the substrate 30 does not hinder the deformation of the flexure element 20.

[0145] Next, the electrodes 31 on the substrate 30 are electrically connected to the corresponding electrodes 15 on the sensor chip 110 by bonding wires (metal wires such as gold wires or copper wires) or the like (not shown). On the substrate 30, the electrodes 31 are formed in the four corner areas of the end face fixing portion 30a that overlap with the upper surfaces (end faces) of the pillars 22a to 22d in a planar view, and the upper surfaces (end faces) of the pillars 22a to 22d are the areas that are least distorted when force is applied to the input portions 24a to 24d. Therefore, this area can be easily pressurized with ultrasonic waves, and wire bonding can be performed stably. The force sensor device 1 is completed through the above steps.

[0146] In this way, the force sensor device 1 can be manufactured using only three components: the sensor chip 110, the strain body 20, and the substrate 30. This makes assembly easy and minimizes the number of alignment points required, thereby reducing the deterioration of accuracy due to implementation.

[0147] Furthermore, since the connection points of the flexure body 20 with the sensor chip 110 (the upper surfaces of the pillars 25a to 25e and the upper surfaces of the protrusions 27a to 27d) are all on the same plane, the sensor chip 110 only needs to be aligned with the flexure body 20 once, making it easy to mount the sensor chip 110 on the flexure body 20.

[0148] 15(b), a step of adhering a cover may be further provided. In the step shown in FIG. 15(b), a cover 50 having openings exposing the input portions 24a to 24d is adhered to the outer periphery of the base 21 so as to cover the upper side of the strain element 20 above the base 21 and the sensor chip 110. The input portions 24a to 24d protrude from the upper surface of the cover 50 through the openings. The cover 50 may be made of, for example, a metal material with a nickel-plated surface.

[0149] The substrate 30 is bonded to the flexure body 20, and the portion of the substrate 30 on which the active components 32 to 35 are mounted is within the height dimension of the flexure body 20 when the substrate 30 is bent. Therefore, the substrate 30 does not hinder the attachment of the cover 50.

[0150] The provision of the cover 50 makes it possible to provide dust protection and electrical noise countermeasures. In particular, noise resistance (signal stability) can be improved by electrically connecting the metallic strain element 20 and cover 50 to the GND of the substrate 30 using silver paste or the like. In this case, it is preferable to provide a GND terminal on the substrate 30 that is in a different series from the sensor chip 110 and active components 32 to 35, and to electrically connect this GND terminal to the strain element 20 and cover 50.

[0151] Here, the shape of the substrate 30 will be described in more detail.

[0152] Fig. 16 is a partially enlarged view of Fig. 2. Fig. 17 is a cross-sectional view taken along line DD in Fig. 16. Fig. 18 is a partially enlarged view of Fig. 16. In Figs. 16 to 18, the four corners of the end surface fixing portion 30a shown in Fig. 13 are electrode arrangement portions 61 to 64, respectively.

[0153] For example, in a plan view, the sensor chip 110 is rectangular, and in a plan view, pillars 22a to 22d are arranged on the extensions of two diagonals of the rectangle. Electrode arrangement sections 61 to 64 are fixed to the upper surface of each pillar. In a plan view, the electrode arrangement sections 61 to 64 may have a shape that is line-symmetrical with respect to the diagonal of the rectangle of the sensor chip 110. In a plan view, the electrode arrangement sections 61 to 64 may have the same shape. Here, the same shape includes a rotationally symmetric shape.

[0154] The lower surfaces of the electrode arrangement sections 61 to 64 are fixed to the upper surfaces of the pillars 22a to 22d, respectively, with resin (adhesive 42 in FIG. 13). Side surface fixing sections 30b to 30e extend from the electrode arrangement sections 61 to 64, and the lower surfaces of the side surface fixing sections 30b to 30e are fixed to the side surfaces of the pillars 22a to 22d with resin (adhesive 43 in FIG. 14). However, the adhesives 42 and 43 are not shown in FIG. 17.

[0155] 18, in a plan view, the outline of the electrode arrangement section 61 includes a first portion 611 that forms the boundary with the side surface fixing section 30e, and a second portion 612 that is continuous with the end of the first portion 611 on the input section 24a side. In addition, in a plan view, the second portion 612 has a portion that protrudes toward the input section 24a with respect to a first imaginary straight line L1 that passes through the end of the first portion 611 on the input section 24a side and is drawn in a direction perpendicular to the longitudinal direction of the beam 23a. In the second portion 612, the portion that protrudes toward the input section 24a with respect to the first imaginary straight line L1 may protrude to the extent that it touches the base of the input section 24a in a cross-sectional view.

[0156] In addition, in a plan view, the outline of the electrode arrangement portion 61 includes a third portion 613 that is the boundary with the side surface fixing portion 30b, and a fourth portion 614 that is continuous with the end of the third portion 613 on the input portion 24d side. In a plan view, the fourth portion 614 has a portion that protrudes toward the input portion 24d with respect to a second imaginary straight line L2 that passes through the end of the third portion 613 on the input portion 24d side and is drawn in a direction perpendicular to the longitudinal direction of the beam 23d. In the fourth portion 614, the portion that protrudes toward the input portion 24d with respect to the second imaginary straight line L2 may protrude to the extent that it touches the base of the input portion 24d in a cross-sectional view.

[0157] The longitudinal direction of the beam refers to the direction of a straight line connecting the centers of gravity of the top surfaces of adjacent columns in a plan view.

[0158] In plan view, the side of the second portion 612 opposite to the side where it is connected to the first portion 611 is continuous with the side of the fourth portion 614 opposite to the side where it is connected to the third portion 613. In addition, in plan view, the side surface of the pillar 22a to which the side surface fixing portion 30e is fixed and the side surface to which the side surface fixing portion 30b is fixed are not parallel to each other. For example, in plan view, the side surface to which the side surface fixing portion 30e is fixed and the side surface to which the side surface fixing portion 30b is fixed are oriented in directions that are approximately perpendicular to each other.

[0159] In this way, in the force sensor device 1, the electrode arrangement portion 61 of the substrate 30 is provided with the second portion 612 and the fourth portion 614 having portions that protrude toward the input portion side. This makes it possible to prevent the resin from creeping up to the upper surface of the electrode arrangement portion 61 in the areas inscribed in the second portion 612 and the fourth portion 614 of the electrode arrangement portion 61, even if a relatively large amount of resin (adhesive 42) is applied to the upper surface of the pillar 22a.

[0160] If the amount of resin applied to the top surface of the pillar 22a is small, the electrode arrangement portion 61 will not be sufficiently flat, which will cause problems when performing wire bonding. In the force sensor device 1, the amount of resin applied can be increased to a certain extent, making it possible to obtain a sufficiently flat electrode arrangement portion 61 and perform wire bonding stably.

[0161] In plan view, the second portion 612 may have a constricted portion 615 that is constricted in the opposite direction to the input portion 24a. For example, by controlling the amount of resin (adhesive 42) applied, it is possible to make a portion of the resin (adhesive 42) flow from the lower surface of the electrode arrangement portion 61 to the upper surface of the electrode arrangement portion 61 via the constricted portion 615, as shown in FIG.

[0162] Furthermore, in plan view, the fourth portion 614 may have a constricted portion 616 that is constricted in the opposite direction to the input portion 24d. For example, by controlling the amount of resin (adhesive 42) applied, it is possible to make a portion of the resin (adhesive 42) flow from the lower surface of the electrode arrangement portion 61 to the upper surface of the electrode arrangement portion 61 via the constricted portion 616, as shown in FIG.

[0163] In this way, by controlling the amount of resin (adhesive 42) applied and causing part of the resin (adhesive 42) to flow around to the upper surface side of the electrode placement section 61, it is possible to improve the fixing strength when fixing the electrode placement section 61 to the pillar 22a. Furthermore, it is possible to visually confirm from the upper surface side of the electrode placement section 61 that a sufficient amount of resin has been applied to the lower surface side of the electrode placement section 61.

[0164] It is preferable to provide an insulating layer 70 that covers at least a portion of the outer edge of the upper surface of the electrode placement section 61 and exposes a portion of the center side. The insulating layer 70 is a so-called solder resist layer and is formed, for example, from an epoxy-based resin or the like. The thickness of the insulating layer 70 is, for example, approximately 30 μm. A conductor layer, such as the electrodes 31 and plated wires extending from the electrodes 31, is formed on the portion of the upper surface of the electrode placement section 61 that is exposed from the insulating layer 70. Note that in Figures 16, 18, and 19, the portion shown with a matte finish is the insulating layer 70. The insulating layer 70 is not shown in Figure 17.

[0165] By providing an insulating layer 70 that covers at least a portion of the outer edge of the upper surface of the electrode placement section 61, it is possible to prevent the resin (adhesive 42) from creeping up onto the upper surface of the electrode placement section 61. Furthermore, by covering the ends of the conductor layers with the insulating layer 70, it is possible to prevent short circuits between the conductor layers. It is more preferable that the insulating layer 70 covers the outer edge of the upper surface of the electrode placement section 61 in a ring shape. This makes it possible to further prevent the resin (adhesive 42) from creeping up onto the upper surface of the electrode placement section 61. It is also possible to further prevent short circuits between the conductor layers.

[0166] Furthermore, when fixing the electrode placement section 61 to the upper surface of the pillar 22a, a resin (adhesive 42) is applied to the upper surface of the pillar 22a, the electrode placement section 61 is placed on the resin, and the upper surface of the electrode placement section 61 is pressed with a jig having a flat surface. When the insulating layer 70 covers the outer edge of the upper surface of the electrode placement section 61 in a ring shape, the entire electrode placement section 61 can be pressed evenly with the flat surface of the jig via the ring-shaped insulating layer 70. This prevents the electrode placement section 61 from tilting with respect to the upper surface of the pillar 22a and improves the fixing strength of the electrode placement section 61.

[0167] Furthermore, by providing the second portion 612 and the fourth portion 614 of the electrode placement section 61 with portions that extend beyond the input section side, the area of ​​the top surface of the electrode placement section 61 is larger than before, which makes it possible to provide the insulating layer 70 on the outer edge of the top surface of the electrode placement section 61, thereby achieving the above-mentioned effect. Even at its narrowest part, the insulating layer 70 can have a thickness of about 200 to 300 μm.

[0168] The above has been described with respect to the electrode placement section 61, but the electrode placement sections 62 to 64 also have the same effect as the electrode placement section 61.

[0169] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. [Explanation of symbols]

[0170] 1 Force sensor device, 15 Electrode, 16 Wiring, 17 Temperature sensor, 20 Strain generating body, 21 Base, 22a to 22d, 25a to 25d, 28 Pillar, 23a to 23d, 26a to 26d Beam, 24a to 24h Input section, 27a to 27d Protrusion, 29a to 29d Joint, 30 Substrate, 30x Opening, 31 Electrode, 32 to 35 Active component, 39 Passive component, 41, 42, 43 Adhesive, 50 Cover, 61 to 64 Electrode arrangement section, 70 Insulating layer, 110 Sensor chip, 111a to 111e Support, 112a to 112h Reinforcing beam, 113a to 113l Detection beam, 114a to 114d Force point, 611 First part, 612 Second part, 613 Third part, 614 Fourth part, 615, 616 Neck part

Claims

1. a sensor chip that detects displacement in a predetermined axial direction; a strain generating body that transmits an applied force to the sensor chip; a substrate for inputting and outputting signals to and from the sensor chip; The strain body is a first pillar and a second pillar arranged adjacent to the periphery of the sensor chip in a plan view; a first beam that connects the first pillar and the second pillar and that deforms when a force is applied; a first input portion to which a force is applied, the first input portion protruding upward from a central portion in a longitudinal direction of the first beam; the substrate includes a first electrode arrangement portion fixed to an upper surface of the first pillar, and a first side surface fixing portion extending from the first electrode arrangement portion and fixed to a first side surface of the first pillar, In a plan view, an outline of the first electrode arrangement portion includes a first portion that is a boundary with the first side surface fixing portion, and a second portion that is continuous with a first end portion of the first portion on the first input portion side, A force sensor device in which, in a planar view, the second portion has a portion that protrudes toward the first input portion with respect to a first imaginary line drawn through the first end in a direction perpendicular to the longitudinal direction of the first beam.

2. The force sensor device according to claim 1 , wherein the second portion has a first constricted portion that is constricted toward the first portion in a plan view.

3. A resin is provided that bonds and fixes the upper surface of the first pillar and the lower surface of the first electrode arrangement portion, The force sensor device according to claim 2 , wherein a portion of the resin extends from the lower surface side of the first electrode arrangement portion to the upper surface side of the first electrode arrangement portion via the first constricted portion.

4. The strain body is third pillars arranged adjacent to the first pillars around the sensor chip in a plan view; a second beam that connects the first pillar and the third pillar and that deforms when a force is applied; a second input portion to which a force is applied, the second input portion projecting upward from a central portion in a longitudinal direction of the second beam; In a plan view, the first pillar has a second side surface that is arranged non-parallel to the first side surface; the substrate includes a second side surface fixing portion extending from the first electrode arrangement portion and fixed to the second side surface, In a plan view, an outline of the first electrode arrangement portion includes a third portion that is a boundary with the second side surface fixing portion, and a fourth portion that is continuous with a second end portion of the third portion on a side of the second input portion, 4. The force sensor device according to claim 1, wherein, in a plan view, the fourth portion has a portion that protrudes toward the second input portion with respect to a second imaginary line drawn through the second end portion in a direction perpendicular to the longitudinal direction of the second beam.

5. The force sensor device according to claim 4 , wherein the fourth portion has a second constricted portion that is constricted toward the third portion in a plan view.

6. A resin is provided that bonds and fixes the upper surface of the first pillar and the lower surface of the first electrode arrangement portion, The force sensor device according to claim 5 , wherein a portion of the resin extends from the lower surface side of the first electrode arrangement portion to the upper surface side of the first electrode arrangement portion via the second constricted portion.

7. 7. The force sensor device according to claim 4, wherein, in a plan view, the second portion has a side opposite to a side connected to the first portion that is continuous with the fourth portion having a side opposite to a side connected to the third portion.

8. an insulating layer is provided that covers at least a portion of the outer edge of the upper surface of the first electrode arrangement portion and exposes a portion of the center side; The force sensor device according to claim 1 , wherein a conductor layer is formed on a portion of the upper surface of the first electrode arrangement portion that is exposed from the insulating layer.

9. The force sensor device according to claim 8 , wherein the insulating layer covers an outer edge of the upper surface of the first electrode arrangement portion in an annular shape.

10. In plan view, the sensor chip is rectangular; In a plan view, four pillars including the first pillar and the second pillar are arranged on extensions of two diagonal lines of the rectangle, 10. The force sensor device according to claim 1, wherein electrode placement sections having the same shape as the first electrode placement section are fixed to upper surfaces of the three pillars other than the first pillar.

11. The force sensor device according to claim 10 , wherein the first electrode arrangement portion has a shape that is line-symmetrical with respect to the diagonal line in a plan view.

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