Load sensor element and method for manufacturing the same

Abstract

A load sensor element comprises: a substrate, which is made of a ceramic material; a rectangular inorganic layer, which has a pressure-bearing surface that bears a load and is arranged in a manner of covering a single surface of the substrate; a thin film resistor, which is a resistor whose resistance value changes according to the load borne by the inorganic layer, and has a main body portion that is placed on the covering portion of a single surface of the substrate in a manner of being sandwiched between the substrate and the inorganic layer, and two end portions that are placed on a single surface of the substrate and are not covered by the inorganic layer; a pair of electrodes that are electrically connected to the two end portions of the thin film resistor in a manner of being separated from the inorganic layer, and are arranged on one side of the substrate.

Description

Technical Field

[0001] The present invention relates to a load sensor element and a method for manufacturing the load sensor element. Background Art

[0002] Japanese Patent Laid-Open No. JP2002-310813A discloses a load sensor element comprising: a pressure-sensing portion formed of a composite material obtained by dispersing a pressure-resistance material in a ceramic material; a pair of insulating portions made of ceramic and disposed on both the upper and lower surfaces of the pressure-sensing portion; and a pair of electrodes disposed on both side surfaces of the pressure-sensing portion. Summary of the invention

[0003] However, in the load sensor element described in Japanese Patent Laid-Open JP2002-310813A, the pressure sensing portion is a sintered body formed by sintering a compact having a certain thickness and obtained by pressing a mixed powder obtained by mixing a ceramic material and a pressure resistor material, and therefore, in the pressure sensing portion, it is difficult to uniformly disperse the pressure resistor material in the ceramic material. Therefore, there is a problem that the detection accuracy of the load sensor element is reduced due to the deviation in the dispersion of the pressure resistor material.

[0004] In addition, since a pair of electrodes are provided on both sides of the pressure-sensing portion in the load sensor element described in Patent Document 1, it is easy for the electrodes to come into contact with a pressure-applying member that applies a load to the load sensor element. Furthermore, when the pressure-applying member is made of a metal material, there is also a problem that the load sensor element is easily short-circuited due to the contact between the electrodes and the pressure-applying member made of the metal material.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a load sensor element and a method for manufacturing the load sensor element that can avoid short circuit and detect a load stably and accurately.

[0006] According to one embodiment of the present invention, there is provided a load sensor element for detecting a load, wherein the load sensor element comprises: a substrate composed of a ceramic material or a metal material having an insulating layer on the surface; an inorganic layer having a pressure-bearing surface that bears the load and arranged to cover a portion of a single surface of the substrate; a thin film resistor, which is a resistor whose resistance value changes according to the load borne by the inorganic layer and has a main body sandwiched between the substrate and the inorganic layer, and two end portions that are placed on an exposed portion of the substrate that is not covered by the inorganic layer; and a pair of electrodes that are electrically connected to the two end portions of the thin film resistor in a manner separated from the inorganic layer and arranged on one side of the substrate.

[0007] According to another embodiment of the present invention, there is provided a method for manufacturing a load sensor element, which detects a load, wherein the method for manufacturing the load sensor element comprises: a process of preparing a substrate layer composed of a ceramic material or a metal material having an insulating layer on the surface; a process of laying a thin film resistor layer on the substrate layer, and laying an electrode layer on the thin film resistor layer; a process of forming a plurality of electrodes by patterning the electrode layer; a process of forming a plurality of thin film resistor bodies having a main body and two ends for carrying a pair of the electrodes by patterning the thin film resistor layer; a process of forming a load sensor element plate having a plurality of unit elements provided with a pair of the electrodes by laying an inorganic layer body, wherein the inorganic layer body is a plurality of inorganic layers corresponding to the number of the main body parts, which are continuously formed in a manner of being separated from the electrodes and covering the plurality of the main body parts; and a process of dividing the load sensor element plate into a plurality of the unit elements.

[0008] This makes it possible to avoid short circuits and detect loads stably and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a perspective view showing the load sensor element according to the first embodiment.

[0010] Figure 2 It is a plan view showing the load sensor element according to the first embodiment.

[0011] Figure 3 It is an exploded perspective view showing the load sensor element according to the first embodiment.

[0012] Figure 4 It is a flowchart showing the manufacturing method of the load sensor element which concerns on 1st Embodiment.

[0013] Figure 5 A schematic diagram showing the preparation process of the substrate layer.

[0014] Figure 6 A schematic diagram showing the steps of laying a thin film resistor layer and an electrode layer.

[0015] Figure 7 It is a schematic diagram showing the process of forming an electrode.

[0016] Figure 8 A schematic diagram showing the steps of forming a thin film resistor.

[0017] Fig. 9 A schematic diagram showing the steps of forming a load sensor element plate.

[0018] Fig.10A schematic diagram showing the division process of a unit element.

[0019] Fig.11 This is a schematic diagram showing the installation process of the guide wire.

[0020] Fig.12 It is a plan view showing a load sensor element according to a second embodiment.

[0021] Fig.13 It is a plan view showing a load sensor element according to a modified example of the second embodiment.

[0022] Fig.14A It is a perspective view showing a load sensor element according to a third embodiment.

[0023] Fig. 14B It is an exploded perspective view showing a load sensor element according to a third embodiment.

[0024] Fig.15 It is a plan view showing a load sensor element according to another modified example of the third embodiment. DETAILED DESCRIPTION

[0025] Hereinafter, the mode for carrying out the invention will be described with reference to the accompanying drawings. In this specification, the same elements are denoted by the same reference numerals throughout.

[0026] (First Embodiment)

[0027] First, refer to Figures 1 to 3 , while describing the load sensor element 1 according to the first embodiment.

[0028] Figure 1 It is a perspective view showing the load sensor element 1 according to the first embodiment. Figure 2 It is a plan view showing the load sensor element 1 according to the first embodiment. Figure 3 1 is an exploded perspective view showing the load sensor element 1 according to the first embodiment. In the figure, the long side direction, the width direction, and the thickness direction of the load sensor element 1 are respectively set as the direction along the X axis, the direction along the Y axis, and the direction along the Z axis. Hereinafter, for the sake of convenience, the long side direction, the width direction, and the thickness direction of the load sensor element 1 are simply referred to as the long side direction, the width direction, and the thickness direction.

[0029] (Load sensor element)

[0030] The load sensor element 1 involved in this embodiment is a sensor element that detects the axial load of a machine tool for the purpose of, for example, preload management. Specifically, the load sensor element 1 moves along the thickness direction (Z-axis direction) by a pressurizing member of a metal material provided in various devices such as a machine tool, thereby detecting the load applied to the load sensor element 1. Figures 1 to 3 As shown, the load sensor element 1 includes a substrate 2, an inorganic layer 3, a thin film resistor 4, and a pair of electrodes 5 (5a, 5b).

[0031] The substrate 2 is rectangular when viewed from above and is made of, for example, an insulating ceramic material. From the viewpoint of increasing the compressive strength of the substrate 2, it is preferred to use zirconium oxide (ZrO2) or aluminum oxide (Al2O3) as the main component of the ceramic material. Since the substrate 2 made of such a material has a small deformation amount relative to pressure and a high rigidity, even when a large load is applied to the load sensor element 1, the substrate 2 will not sink or bend like a resin material substrate. As a result, the reduction in detection accuracy caused by the deformation of the substrate 2 is suppressed, and the load sensor 1 can detect the load with high accuracy.

[0032] In addition, from the perspective of achieving both an improvement in the compressive strength of the substrate 2 and a reduction in the thickness of the load sensor element 1, it is preferred that the thickness of the substrate be greater than or equal to 0.3 mm and less than or equal to 5.0 mm. When the thickness of the substrate 2 is less than 0.3 mm, when a large load is applied to the load sensor element 1, the substrate 2 bends, and therefore, it is not possible to suppress a reduction in detection accuracy due to the bending of the substrate 2. On the other hand, when the thickness of the substrate 2 exceeds 5.0 mm, even if a large load is applied to the load sensor element 1, the substrate 2 does not bend, and the load sensor element 1 can detect the large load with high accuracy. However, since the thickness of the substrate 2 is increased accordingly, it is not possible to fully achieve a reduction in the thickness of the entire load sensor element 1.

[0033] Preferably, the upper surface of the substrate 2 on which the thin film resistor 4 is formed is polished so that its flatness becomes 1 μm or less. Thus, the thin film resistor 4 can be formed on the upper surface of the substrate 2 with a uniform thickness. As a result, a decrease in detection accuracy caused by variations in the thickness of the thin film resistor 4 is suppressed.

[0034] The upper surface of the substrate 2 has a rectangular (including the positive direction) covering portion 21 covered by the inorganic layer 3, and a rectangular exposed portion 22 not covered by the inorganic layer 3. Since the area of ​​the thin film resistor 4 (especially the main body 41 described later) that will contribute to the detection of the load is ensured to be large, the covering portion 21 is formed in a manner larger than the exposed portion 22. The main body 41 of the thin film resistor 4 is provided on the covering portion 21. On the exposed portion 22, a pair of electrodes 5 (5a, 5b) are provided through the two end portions 42 of the thin film resistor 4 described later.

[0035] The inorganic layer 3 is a pressure-bearing portion having a pressure-bearing surface 31 that bears the load applied by a pressurizing member (not shown). That is, the pressure-bearing surface 31 is the back side of the surface opposite to the substrate 2 in the inorganic layer 3. The inorganic layer 3 is rectangular (including square) when viewed from above, similarly to the substrate 2, and is composed of, for example, an insulating ceramic substrate. Preferably, zirconium oxide (ZrO2) or aluminum oxide (Al2O3) is used as the main component of the ceramic material, similarly to the substrate 2. Thereby, even when a large load is applied to the load sensor element 1, the inorganic layer 3 will not sink or bend or deform like a resin material substrate. As a result, the reduction in detection accuracy caused by the deformation of the inorganic layer 3 is suppressed, and the load sensor 1 can detect the load with high accuracy.

[0036] In addition, from the perspective of achieving both improved compressive strength and thinning of the load sensor element 1, it is preferred that the thickness of the inorganic layer 3 is greater than 0.3 mm and less than 5.0 mm. When the thickness of the inorganic layer 3 is less than 0.3 mm, when a large load is applied to the load sensor element 1, the inorganic layer 3 bends, and therefore, the reduction in detection accuracy caused by the bending of the inorganic layer 3 cannot be suppressed. On the other hand, when the thickness of the inorganic layer 3 exceeds 5.0 mm, even if a large load is applied to the load sensor element 1, the inorganic layer 3 does not bend, and the load sensor element 1 can detect the large load with high accuracy. However, since the thickness of the inorganic layer 3 is increased accordingly, the overall thinning of the load sensor element 1 cannot be fully achieved. Thereby, both improved compressive strength of the inorganic layer 3 and thinning of the load sensor element 1 can be achieved. In addition, although the substrate 2 and the inorganic layer 3 can use substrates and inorganic layers of the same thickness, substrates and inorganic layers of different thicknesses can also be used.

[0037] The inorganic layer 3 covers a portion of the surface of the substrate 2. That is, the inorganic layer 3 does not cover the exposed portion 22 of the substrate 2 provided with the electrodes 5 (5a, 5b) through the two end portions 42 of the thin film resistor 4, but is provided to define the covering portion 21 relative to the area provided with the main body 41 of the thin film resistor 4. For example, in the case where the load sensor element has a pressure-receiving portion covering the electrode, when the load sensor element is subjected to a load, the electrodes are pressurized together, and the output signal may be deviated. On the other hand, in the present embodiment, the load sensor element 1 does not have an electrode on the pressure-receiving portion subjected to the load, and therefore, such a deviation does not occur, and the load can be detected with high accuracy.

[0038] The substrate 2 of the load sensor element 1 has a covering portion 21 covered with the inorganic layer 3 and an exposed portion 22 not covered with the inorganic layer 3. Therefore, the user can easily distinguish the substrate 2 and the inorganic layer 3, and can assemble the load sensor element 1 in such a manner that the pressure-receiving surface 31 of the inorganic layer 3 faces the top end of the pressurizing member. Thereby, the situation in which the load sensor element 1 is assembled in such a manner that the substrate 2 is mistakenly facing the top end of the pressurizing member is reliably avoided.

[0039] From the viewpoint of achieving both a reduction in the load on the main body 41 and an improvement in the detection accuracy, it is preferred that the area of ​​the pressure receiving surface 31 of the inorganic layer 3 covering the main body 41 is 60 mm 2 Above and 70mm 2 When the area is within this range, the main body 41 is unlikely to be destroyed by a large load (for example, 3.5 kN), and a small load (for example, 3 N) can be detected with high accuracy.

[0040] The inorganic layer 3 is provided on the cover portion 21 of the substrate 2 and the body portion 41 of the thin film resistor 4 via an adhesive layer (not shown) made of a resin material. In the present embodiment, the adhesive layer contains epoxy resin as a main component.

[0041] Preferably, the lower surface of the inorganic layer 3 facing the thin film resistor 4 is polished to have a flatness of 1 μm or less. This allows the inorganic layer 3 to be provided on the adhesive layer with high accuracy.

[0042] The thin film resistor 4 is a resistor whose resistance value changes according to the load on the inorganic layer 3. The thin film resistor 4 is made of, for example, a nickel-chromium (NiCr) material or a chromium (Cr) material. As a result, the load sensor 1 can detect the load with high accuracy even in a high temperature environment of 50°C or above because the temperature coefficient of resistance (TCR) is small.

[0043] The thin film resistor 4 is a resistor film formed on the upper surface of the substrate 2 by vacuum processing such as vapor deposition or vacuum sputtering. Thus, a uniform resistor film is formed by vacuum processing such as vapor deposition or vacuum sputtering, thereby suppressing the dispersion of the resistor. Thus, the load sensor element 1 can detect the load with high accuracy.

[0044] Preferably, the thin film resistor 4 is formed in a manner that its thickness is greater than 0 and less than 1 μm. Thereby, even when a large load is applied to the load sensor element 1, there is almost no sinking of the thin film resistor 4, thereby suppressing the reduction in detection accuracy caused by the sinking of the resistor. In addition, the load sensor element 1 can be further thinned. In addition, it is more preferred that the thickness of the thin film resistor 4 is greater than 5 nm and less than 1 μm.

[0045] The thin film resistor 4 has: a main body 41, which is placed on the covering portion 21 of the substrate 2 in a manner sandwiched between the substrate 2 and the inorganic layer 3; and two end portions 42, which are placed on the exposed portion 22 of the substrate 2 that is not covered by the inorganic layer 3. The inorganic layer 3 only needs to not cover the electrode, and may also cover a portion of the one end side connecting portion 422a and / or the other end side connecting portion 422b described later. In the present embodiment, the boundary portion between the main body 41 (the winding pattern portion) and the connecting portions 422a, 422b and the boundary portion between the covering portion 21 and the exposed portion 22 are substantially consistent. Thereby, the boundary portion between the main body 41 (the winding pattern portion) and the connecting portions 422a, 422b can be positioned as the setting position of the inorganic layer 3. Therefore, the situation in which the unintentional part of the thin film resistor 4 is pressurized due to the position deviation of the inorganic layer 3 is suppressed, and the deviation of the detection accuracy can be suppressed.

[0046] The main body 41 extends in the width direction and is formed in a substantially line-symmetrical shape with a substantially uniform thickness over substantially the entire region of the cover portion 21 (inorganic layer 3) of the substrate 2. As a result, since the load applied to the pressure-bearing surface 31 of the inorganic layer 3 is easily and uniformly dispersed to the main body 41 formed in a meandering shape without deviation, the load sensor element 1 can detect the load with high accuracy.

[0047] The main body 41 of the thin film resistor 4 sandwiched between the substrate 2 and the inorganic layer 3 is composed of a winding resistor pattern, so that the resistance value of the thin film resistor 4 can be increased and the power consumption of the thin film resistor 4 can be reduced. In addition, by changing the pattern shape of the main body 41, the resistance value of the thin film resistor 4 can be easily designed.

[0048] In the present embodiment, the main body 41 of the thin film resistor 4 is formed in a meandering pattern, but the present invention is not limited thereto and may be formed uniformly over the entire region of the cover portion 21 (inorganic layer 3 ) of the substrate 2 .

[0049] In the present embodiment, the outer shape of the main body 41 is substantially rectangular. The main body 41 is a meandering pattern (meandering pattern), and has: a plurality of (e.g., eight) extensions 41 arranged in a manner extending along the long side direction; a plurality of (e.g., four) one-end side connecting portions 412 connecting one ends of adjacent extensions 411 to each other; and a plurality of (e.g., three) other-end side connecting portions 413 connecting the other ends of adjacent extensions 411 to each other.

[0050] The plurality of extension portions 411 have a predetermined width and are arranged at predetermined intervals in the width direction. The plurality of one-end side connecting portions 412 and the plurality of other-end side connecting portions 413 are alternately arranged in the width direction. In addition, by changing the width of the extension portion 411, the resistance value of the thin film resistor 4 can be easily designed.

[0051] The two end portions 42 are composed of a pair of one end portion 42a and the other end portion 42b. The one end portion 42a and the other end portion 42b are provided in a separated manner. This prevents a short circuit caused by contact between the one end portion 42a and the other end portion 42b.

[0052] The one end portion 42a has: a rectangular one end side electrode connecting portion 421a as the electrode connecting portion 421, on which the electrode 5a is provided; and a one end side connecting portion 422a as the connecting portion 422, which connects one end of the main body 41 and the one end side electrode connecting portion 421a.

[0053] Similarly, the other end portion 42b has: a rectangular other end side electrode connecting portion 421b as the electrode connecting portion 421, on which the electrode 5b is set; and an other end side connecting portion 422b as the connecting portion 422, which connects the other end of the main body 41 and the other end side electrode connecting portion 421b.

[0054] Thereby, the electrode connection part 421 can be provided on the exposed part 22 of the substrate 2 in a manner separated from the inorganic layer 3. As a result, a pair of electrodes 5a, 5b are provided on the electrode connection parts 421a, 421b, respectively, in a manner separated from the inorganic layer 3. That is, the surface block of the substrate 2 is divided into two by the inorganic layer 3 and the exposed part 22, and the electrodes 5a, 5b are all concentratedly provided on one side of the substrate 2 which is the exposed part 22. The electrodes 5a, 5b are formed on the same surface where the thin film resistor 4 is formed, that is, one side of the substrate 2. Therefore, when the pressure member applies a load to the inorganic layer 3, contact with the electrode 5 can be avoided, thereby avoiding short circuit and damage of the load sensor element 1 caused by contact between the electrodes 5a, 5b and the pressure member.

[0055] The one-end side electrode connection part 421a is provided so that its width is larger than the width of the extension part 411 constituting the main body part 41. Similarly, the other-end side electrode connection part 421b is provided so that its width is larger than the width of the extension part 411 constituting the main body part 41. In this way, by making the electrode connection part 421 (421a, 421b) larger in width, the resistance value of the two end parts 42 (42a, 42b) can be made smaller than the resistance value of the main body part 41 of the meandering pattern.

[0056] The one-end connecting portion 422a is formed into a tapered shape whose width increases from the extension portion 411 side toward the one-end electrode connecting portion 421a side. Similarly, the other-end connecting portion 422b is formed into a tapered shape whose width increases from the extension portion 411 side toward the other-end electrode connecting portion 421b side.

[0057] In addition, by marking the boundary line between the extension portion 411 and the tapered connecting portion 422 (422a, 422b), the inorganic layer 3 is placed in the region of the covering portion 21 of the substrate 2, thereby avoiding the situation where the inorganic layer 3 is mistakenly covered in the region of the exposed portion 22 of the substrate 2.

[0058] The pair of electrodes 5 (5a, 5b) are separated from the inorganic layer 3 and are provided so as to be electrically connected to both ends 42 (42a, 42b) of the thin film resistor 4. The pair of electrodes 5 (5a, 5b) are made of materials such as copper (Cu), silver (Ag), and gold (Au).

[0059] Specifically, the pair of electrodes 5 (5a, 5b) are provided on the connecting portion 422 (422a, 422b) of both end portions 42 (42a, 42b) separated from the inorganic layer 3. Thus, the pair of electrodes 5 (5a, 5b) can be provided separated from the inorganic layer 3.

[0060] A pair of external connection terminals may also be installed on the pair of electrodes 5 (5a, 5b) in a manner of being electrically connected to each other. The external connection terminals are guide wires 6 (6a, 6b). Specifically, the pair of guide wires 6a, 6b are respectively installed on the pair of electrodes 5a, 5b by welding. In addition, the pair of guide wires 6 are made of materials such as copper (Cu). In addition to being guide wires, the external connection terminals are also wiring that can transmit the output signal of the load sensor element 1 to the processing device regardless of other forms such as covering wires and guide frames.

[0061] (Manufacturing method of load sensor element)

[0062] Next, refer to Figures 3 to 11 , while explaining a method for manufacturing the load sensor element 1.

[0063] Figure 4 1 is a flowchart showing a method for manufacturing the load sensor element 1 . Figure 5 It is a schematic diagram showing the preparation process of the substrate layer 7. Figure 6 It is a schematic diagram showing the process of laying the thin film resistance layer 8 and the electrode layer 9. Figure 7 It is a schematic diagram showing the formation process of the electrode 5. Figure 8 Schematic diagram showing the steps of forming the thin film resistor 4 . Fig. 9 It is a schematic diagram showing the formation process of the load sensor element plate 11. Fig.10 Schematic diagram showing the process of dividing the unit cell 12. Fig.11 It is a schematic diagram showing the installation process of the guide wire 6.

[0064] like Figure 4 As shown, the manufacturing method of the load sensor element 1 includes the following steps: preparing a substrate layer S1, laying a thin film resistor layer and an electrode layer S2, forming an electrode S3, forming a thin film resistor body S4, performing a heat treatment of the thin film resistor body S5, adjusting the resistance value of the thin film resistor body S6, forming a load sensor element plate S7, and dividing the load sensor element plate into unit elements S8.

[0065] First, if Figure 5 As shown, in step S1, a substrate layer 7 made of a ceramic material is prepared. Specifically, in step S1, the upper surface of the large rectangular substrate layer 7 including a plurality of rectangular substrates 2 is polished so that the flatness becomes less than 1 μm. Then, in order to prepare for the unit element division in step S8, a plurality of unit elements 12 are formed on the substrate layer 7 (see Fig.10 ) method, the dividing grooves 13 are formed in the substrate layer 7.

[0066] In the present embodiment, the dividing grooves 13 are formed in the substrate layer 7 , but the present invention is not limited thereto. For example, a dividing mark may be formed, or the dividing grooves 13 may not be formed.

[0067] Then, if Figure 6 As shown, in step S2, a thin film resistor layer 8 made of a nickel-chromium alloy (NiCr) material is sequentially laid (laminated) on the substrate layer 7 (see Figure 7 ) and an electrode layer 9 composed of copper (Cu). Specifically, in step S2, a thin film resistor layer 8 composed of a nickel-chromium alloy (NiCr) material is uniformly applied on the upper surface of the substrate layer 7 by vacuum sputtering, and an electrode layer 9 composed of copper (Cu) is uniformly applied on the upper surface of the thin film resistor layer 8 by vacuum sputtering.

[0068] Then, if Figure 7 As shown, in step S3, a plurality of electrodes 5 are formed by patterning the electrode layer 9. Specifically, in step S3, a photoresist is applied to the electrode layer 9 and dried, and then the electrode layer 9 is patterned to obtain a plurality of electrodes 5, and is covered with a shielding material (photomask) in such a way that the photoresist remains in a pattern (electrode 5 shape). In addition, by irradiating the exposed portion of the photoresist not covered by the shielding material with ultraviolet rays or the like, the portion of the photoresist not covered by the shielding material is exposed. Then, the exposed photoresist is removed by an alkaline solution, and the electrode layer 9 not covered by the shielding material is removed by etching. A plurality of electrodes 5 are formed by stripping off the remaining photoresist.

[0069] Then, if Figure 8 As shown, in step S4, a thin film resistor layer 8 is formed in the same manner as step S3 (see Figure 7 ) is patterned to form a plurality of thin film resistors 4. Specifically, in step S4, a photoresist is applied on the thin film resistor layer 8 and dried, and then the thin film resistor layer 8 is patterned to obtain a plurality of thin film resistors 4, and covered with a shielding material (photomask) in such a way that the photoresist remains in a pattern (thin film resistor layer 8 shape and electrode 5 shape). In addition, by irradiating the exposed portion of the photoresist not covered by the shielding material with ultraviolet rays or the like, the portion of the photoresist not covered by the shielding material is exposed. Then, the exposed photoresist is removed by an alkaline solution, and the thin film resistor layer 8 not covered by the shielding material is removed by etching. By removing the remaining photoresist, a plurality of thin film resistors 4 are formed, and the plurality of thin film resistors 4 have a main body 41 and two end portions 42 on which a pair of electrodes 5 (5a, 5b) are placed.

[0070] Next, in step S5, a heat treatment is performed on the thin film resistor 4. This can stabilize the thin film resistor 4. As a result, the load sensor element 1 can detect the load with high accuracy even in a high temperature environment of 50°C or higher.

[0071] Next, in step S6, the resistance value of the thin film resistor 4 is adjusted. Specifically, in step S6, the resistance value between the pair of electrodes 5a and 5b is detected, and the body portion 41 of the thin film resistor 4 is cut and trimmed by laser or the like so as to obtain a predetermined resistance value, thereby adjusting the resistance value of the thin film resistor 4. In addition, this step S6 is not a necessary step and may not be performed.

[0072] Then, if Fig. 9 As shown, in step S7, the inorganic layer 10 is laid through an adhesive layer (not shown) to form a plurality of unit elements 12 (see Fig.10 Specifically, in step S7, a load sensor element plate 11 having a plurality of unit elements 12 provided with a pair of electrodes 5 (5a, 5b) is formed by laying a plurality of inorganic layer sheets 10 as inorganic layer bodies, wherein the inorganic layer sheets 10 are a plurality of inorganic layers 3 (see Fig.10 ) is continuously formed in a manner separated from the electrode 5 and covering multiple main body parts 41.

[0073] Then, if Fig.10 As shown, in step S8, the load sensor element plate 11 (see Fig. 9 ) is divided into a plurality of unit elements 12. Specifically, in step S8, a dicing blade, a laser, or the like is used to cut the unit elements 12 along the previously formed dividing grooves 13 (see Figure 1 ) and divide the load sensor element plate 11 into a plurality of unit elements 12.

[0074] In addition, if Fig.11 As shown, each unit element 12 ( Fig.10 ) is mounted on a pair of lead wires 6a, 6b made of copper (Cu). Specifically, a pair of lead wires 6a, 6b are mounted on a pair of electrodes 5a, 5b in each unit element 12 divided in step S8 by welding. In this way, a plurality of load sensor elements 1 are formed.

[0075] Next, the effects of this embodiment will be described.

[0076] As described above, the load sensor element 1 involved in the present embodiment detects the load and comprises: a substrate 2, which is made of a ceramic material; an inorganic layer 3, which has a pressure-bearing surface 31 that bears the load and is arranged in a manner of a covering portion 21 that covers the upper surface of the substrate 2; a thin film resistor 4, which is a resistor whose resistance value changes according to the load borne by the inorganic layer 3, and has a main body 41 sandwiched between the substrate 2 and the inorganic layer 3, and two end portions 42 (42a, 42b) of an exposed portion 22 that is not covered by the inorganic layer 3 and is carried on the substrate 2; a pair of electrodes 5, which are separated from the inorganic layer 3 and are electrically connected to the two end portions 42 (42a, 42b) of the thin film resistor 4, and are arranged on one side of the substrate 2.

[0077] Thus, since the substrate 2 is made of a ceramic material, even when a large load is applied to the load sensor element 1, the substrate 2 does not sink, bend, or deform like a resin material substrate. As a result, the reduction in detection accuracy due to deformation of the substrate 2 is suppressed, and the load sensor 1 can detect such a large load with high accuracy.

[0078] In addition, since the inorganic layer 3 is not configured to cover the entire area of ​​the upper surface of the substrate 2, but is configured as a covering layer 21 covering the upper surface of the substrate 2, it is possible to easily distinguish between the substrate 2 and the inorganic layer 3, and to assemble the load sensor element 1 in such a manner that the pressure-bearing surface 31 of the inorganic layer 3 faces the pressure-applying component.

[0079] As the resistor whose resistance value changes according to the load on the inorganic layer 3, a uniform thin film resistor 4 formed by vacuum processing such as vapor deposition or vacuum sputtering is used, so that the dispersion of the resistor is suppressed. Thus, the load sensor element 1 can detect the load with high accuracy.

[0080] The thin film resistor 4 has a main body 41 placed on the cover 21 of a single surface of the substrate 2 in a manner sandwiched between the substrate 2 and the inorganic layer 3, and two end portions 42 (42a, 42b) placed on the exposed portion 22 of the substrate 2 not covered by the inorganic layer 3. That is, the inorganic layer 3 does not cover the exposed portion 22 of the substrate 2 where the two end portions 42 (42a, 42b) of the thin film resistor 4 are provided, but only covers the cover 21 of the substrate 2 where the main body 41 of the thin film resistor 4 is provided. Thus, compared with a load sensor element having a pressure receiving portion including a covering electrode, etc., the load sensor element 1 can detect the load with high accuracy without picking up unnecessary signals.

[0081] Since a pair of electrodes 5 are arranged in a manner separated from the inorganic layer 3 and electrically connected to the two end portions 42 (42a, 42b) of the thin film resistor 4, contact between the electrodes 5 (5a, 5b) and a pressure component that applies a load to the inorganic layer 3 is reliably avoided, thereby avoiding a short circuit of the load sensor element 1 caused by contact between the electrodes 5 (5a, 5b) and the pressure component.

[0082] As described above, according to the load sensor element 1 according to the present embodiment, it is possible to avoid a short circuit and detect the load stably and accurately.

[0083] In addition, in the present embodiment, the inorganic layer 3 is composed of a ceramic substrate and is provided on the main body portion 41 via an adhesive layer.

[0084] Thus, since the inorganic layer 3 provided on the main body 41 via the adhesive layer is composed of a ceramic substrate, even when a large load is applied to the load sensor element 1, the inorganic layer 3 does not sink, bend, or deform like a resin material substrate. As a result, the reduction in detection accuracy due to deformation of the inorganic layer 3 is suppressed, and the load sensor 1 can detect such a large load with high accuracy.

[0085] In addition, in the present embodiment, the thickness of the substrate 2 is greater than or equal to 0.3 mm and less than or equal to 5.0 mm.

[0086] Thus, by controlling the thickness of the substrate 2 to be not less than 0.3 mm and not more than 5.0 mm, it is possible to achieve both improvement in the compressive strength of the substrate 2 and reduction in the thickness of the load sensor element 1 .

[0087] In addition, in the present embodiment, the thin film resistor 4 is made of a NiCr-based material or a Cr-based material.

[0088] Thus, since the temperature coefficient of resistance is small, the load sensor 1 can detect the load with high accuracy even in a high temperature environment of 50° C. or higher.

[0089] In addition, in the present embodiment, the thickness of the thin film resistor 4 is greater than 0 and is 1 μm or less.

[0090] Thus, by setting the thickness of the thin film resistor 4 to be greater than 0 and less than 1 μm, even when a large load is applied to the load sensor element 1, there is almost no sinking of the thin film resistor 4, thereby suppressing the reduction in detection accuracy caused by the sinking of the resistor. In addition, the load sensor element 1 can be further thinned.

[0091] In addition, in the present embodiment, the main body portion 41 is formed of a pattern formed in a meandering shape (a meandering pattern portion).

[0092] Thus, since the main body 41 whose resistance value changes according to the load borne by the inorganic layer 3 is composed of the meandering pattern portion, the resistance value of the thin film resistor 4 can be increased and the power consumption of the thin film resistor 4 can be reduced. In addition, the resistance value of the thin film resistor 4 can be easily adjusted by changing the pattern of the meandering pattern portion.

[0093] In addition, in this embodiment, the two end portions 42 (42a, 42b) have: an electrode connecting portion 421 (421a, 421b) on which a pair of electrodes 5 are provided; and a connecting portion 422 (422a, 422b) that connects the main body 41 and the electrode connecting portion 421 (421a, 421b).

[0094] Thus, the two end portions 42 (42a, 42b) have an electrode connection portion 421 (421a, 421b) on which a pair of electrodes 5 (5a, 5b) are provided, and a connection portion 422 (422a, 422b) that connects the main body 41 and the electrode connection portion 421, so that the electrode connection portion 421 (421a, 421b) can be provided on the exposed portion 22 of the substrate 2 in a manner separated from the inorganic layer 3. As a result, since the pair of electrodes 5 (5a, 5b) are provided on the electrode connection portion 421 (421a, 421b) in a manner separated from the inorganic layer 3, the contact between the electrodes 5 (5a, 5b) and the pressure member that applies a load to the inorganic layer 3 is reliably avoided, and a short circuit and damage to the load sensor element 1 caused by the contact between the electrodes 5 (5a, 5b) and the pressure member is avoided.

[0095] On the other hand, the manufacturing method of the load sensor element 1 involved in the present embodiment includes: a process of preparing a substrate layer 7 composed of a ceramic material; a process of laying a thin film resistor layer 8 on the substrate layer 7 and laying an electrode layer 9 on the thin film resistor layer 8; a process of forming a plurality of electrodes 5 by patterning the electrode layer 9; a process of forming a plurality of thin film resistor bodies 4 by patterning the thin film resistor layer 8, wherein the thin film resistor body 4 has a winding main body 41 and two end portions 42 for carrying a pair of electrodes 5 (5a, 5b); a process of forming a load sensor element plate 11 having a plurality of unit elements 12 provided with a pair of electrodes 5 (5a, 5b) by laying an inorganic layer body 10, wherein the inorganic layer body 10 is a plurality of inorganic layers 3 corresponding to the number of main bodies 41, which are continuously formed in a manner separated from the electrodes 5 and covering the plurality of main bodies 41; and a process of dividing the load sensor element plate 11 into a plurality of unit elements 12.

[0096] Thereby, it is possible to manufacture the load sensor element 1 which can avoid short circuit and damage of the electrode 5 and detect the load stably and with high accuracy.

[0097] (Modification of the first embodiment)

[0098] Although the substrate 2 is made of a ceramic material in the above embodiment, it is not limited thereto and may be made of, for example, a metal material, etc. In this case, it is necessary to perform an insulation treatment (by configuring a metal oxide or an insulating material by coating, etc.) on a single surface (upper surface) of the substrate 2 on which the thin film resistor 4 is formed, thereby forming an insulating layer.

[0099] Thus, since the substrate 2 is made of a metal material, it is possible to obtain an effect that the substrate 2 has better processability than a ceramic material.

[0100] In addition, although in the above embodiment, the inorganic layer 3 is composed of a ceramic substrate like the substrate 2, it is not limited thereto and may be composed of, for example, an aluminum oxide protective film. In this case, a uniform aluminum oxide protective film is directly formed on the thin film resistor 4 by vacuum processing such as vapor deposition and vacuum sputtering without passing through an adhesive layer.

[0101] Thus, since the inorganic layer 3 is composed of an aluminum oxide protective film, the adhesive layer sandwiched between the thin film resistor 4 and the inorganic layer 3 can be eliminated. Thus, when a large load is applied to the load sensor element 1, the decrease in detection accuracy due to the sinking of the adhesive layer is suppressed. In addition, the load sensor element 1 can be made thinner.

[0102] In this modification, the aluminum oxide protective film is formed so that the thickness thereof is 3 μm or more and smaller than the thickness of the substrate 2 .

[0103] Thus, by controlling the thickness of the aluminum oxide protective film to be 3 μm or more and smaller than the thickness of the substrate 2 , it is possible to achieve both improvement in the compressive strength of the inorganic layer 3 and reduction in the thickness of the load sensor element 1 .

[0104] In addition, when the inorganic layer 3 is composed of an aluminum oxide protective film, the manufacturing method of the load sensor element 1 including the inorganic layer 3 composed of an aluminum oxide protective film includes steps S1 to S8 in the same manner as the manufacturing method described in the above embodiment. Among them, in step S7, an inorganic film layer as an inorganic layer body is applied on the cover portion 21 of the substrate 2 by vacuum treatment such as vapor deposition and vacuum sputtering, thereby forming a load sensor element plate 11 having a plurality of unit elements 12 provided with a pair of electrodes 5 (5a, 5b), wherein the inorganic film layer is a plurality of inorganic layers 3 corresponding to the number of the main body portions 41, which are separated from the electrodes 5 and cover the plurality of main body portions 41, and are continuously formed.

[0105] (Second Embodiment)

[0106] Below, while referring to Fig.12 , a load sensor element 1 according to a second embodiment will be described. In the second embodiment, descriptions of points common to the first embodiment will be omitted, and points different from the first embodiment will be mainly described.

[0107] Fig.12 It is a plan view showing a load sensor element according to a second embodiment.

[0108] Although the main body 41 of the thin film resistor 4 is formed of a meandering pattern in the first embodiment, the present invention is not limited thereto. For example, the main body 41 may be formed of a U-shaped pattern portion 41A (see FIG. 1 ) as in the second embodiment. Fig.12 ) or a V-shaped pattern portion (not shown).

[0109] like Fig.12 As shown in FIG. 1 , the main body 41A formed by the U-shaped pattern is connected to the electrode connecting portion 421A via the taper 422A as a connecting portion, similarly to the main body 41 formed by the meandering pattern described above. The main body 41A is placed at the center of the cover 21 on the upper surface of the substrate 2. Thus, even when the substrate 2 is used in a state of being warped toward the center, a load is applied to the main body 41A, and thus the load can be detected with high accuracy.

[0110] (Variation of the Second Embodiment)

[0111] Although the load sensor element 1 does not include a positioning portion in the second embodiment, the present invention is not limited thereto. For example, the load sensor element 1 may include a positioning portion. Fig.13 As shown in the modified example, a positioning portion 14 is provided for positioning the load sensor element 1. In addition, Fig.13 It is a plan view showing a load sensor element 1 according to a modified example of the second embodiment.

[0112] like Fig.13 As shown, the positioning portion 14 is provided in a manner that does not interfere with the U-shaped pattern portion 41A as the main body. The positioning portion 14 is composed of two positioning pins 141. Each positioning pin 141 has: a cylindrical through-portion 141a, which is penetrated by a circular through-hole formed in the substrate 2 and the inorganic layer 3; and a head 141b, which is provided at one end of the through-portion 141a. In addition, the head 141b is formed coaxially with the through-portion 141a in a manner that its outer diameter is larger than the outer diameter of the through-portion 141a.

[0113] Thus, the load sensor element 1 can be assembled at a determined position only by using the positioning portion 14 , thereby improving positioning accuracy and making it difficult for positioning deviation of the assembled load sensor element 1 to occur, thereby improving detection accuracy of the load sensor element 1 .

[0114] In this modification, the positioning portion 14 is composed of two positioning pins 141 , but the present invention is not limited thereto and may be composed of, for example, two screws.

[0115] In addition, although in this modification, the positioning portion 14 passes through the through hole formed in the substrate 2 and the inorganic layer 3, it is not limited to this, and it can also be a notch or groove that engages with the positioning portion 14 instead of the through hole. In this case, the notch or groove only needs to be formed in at least one of the substrate 2 and the inorganic layer 3.

[0116] (Third Embodiment)

[0117] Below, while referring to Fig.14A as well as Fig. 14B , a load sensor element 1 according to a third embodiment will be described. In the third embodiment, description of the same points as the first embodiment will be omitted, and description will be mainly made of points different from the first embodiment.

[0118] Fig.14A It is a perspective view showing a load sensor element 1 according to a third embodiment. Fig. 14B It is an exploded perspective view showing a load sensor element 1 according to a third embodiment.

[0119] Although the substrate 2 and the inorganic layer 3 are both formed into a rectangular shape in the first embodiment, the present invention is not limited thereto and may also be formed into a rectangular shape. Fig.14A as well as Fig. 14B As shown, the substrate 2 is formed into a circular shape, and the inorganic layer 3 is formed into a notched circular shape. In addition, the notched circular shape includes an arch shape, a D-cut shape (refer to Fig.14A as well as Fig. 14B )wait.

[0120] like Fig.14A as well as Fig. 14B As shown, in this embodiment, the circular upper surface of the substrate 2 has: a D-cut-shaped covering portion 21A, which is covered by the inorganic layer 3; and an arch-shaped exposed portion 22A, which is not covered by the inorganic layer 3. The main body 41B of the thin film resistor 4 is provided on the D-cut-shaped covering portion 21A. A pair of electrodes 5 are provided on the arch-shaped exposed portion 22A through the two end portions 42B of the thin film resistor 4.

[0121] The main body 41B is formed of an arc-shaped meandering pattern provided so as to extend on the same arc with the center of the substrate 2 as the center. That is, the main body 41B is formed of an arc-shaped meandering pattern along the outer shape of the substrate 2. The main body 41B is provided so that one end thereof is connected to one of the two end portions 42B, and the other end thereof is connected to the other of the two end portions 42B.

[0122] Thus, the load applied to the pressure receiving surface 31 of the inorganic layer 3 can be easily and more uniformly distributed to the main body portion 41B without causing any deviation, and therefore the load sensor element 1 can detect such a load with higher accuracy.

[0123] (Variation of the Third Embodiment)

[0124] In the third embodiment, the main body portion 41B is formed of the arc-shaped meandering pattern portion, but the present invention is not limited thereto, and for example, the main body portion 41B may be formed of a simple arc-shaped pattern portion.

[0125] In addition, although the load sensor element 1 does not include a positioning portion in the third embodiment, the present invention is not limited thereto. For example, the load sensor element 1 may include a positioning portion. Fig.15 As shown in another modified example, a positioning portion 14A is provided for positioning the load sensor element 1. In addition, Fig.15 It is a perspective view showing a load sensor element 1 according to another modified example of the third embodiment.

[0126] like Fig.15 As shown in FIG. 1 , the positioning portion 14A is provided so as not to interfere with the meandering pattern portion of the main body portion 41B. The positioning portion 14A is formed by the main body portion 41B (see FIG. 1 ) which is a meandering pattern. Fig. 14B ) and is surrounded by a positioning pin.

[0127] Thus, the load sensor element 1 can be assembled at a determined position only by using the positioning portion 14A, thereby improving positioning accuracy and making it difficult for positioning deviation of the assembled load sensor element 1 to occur, thereby improving detection accuracy of the load sensor element 1 .

[0128] In the present modification, the positioning portion 14A is formed of one positioning pin, but the present invention is not limited thereto and may be formed of, for example, one screw.

[0129] In addition, although in this modification, the positioning portion 14A penetrates the through hole formed in the substrate 2 and the inorganic layer 3, it is not limited to this, and it can also be, for example, a notch or groove engaged with the positioning portion 14A, instead of the through hole. In this case, the notch or groove only needs to be formed in at least one of the substrate 2 and the inorganic layer 3.

[0130] Although the present embodiment has been described above, the above embodiment merely shows a part of application examples of the present invention, and does not limit the technical scope of the present invention to the specific configuration of the above embodiment.

[0131] This application claims priority based on Japanese Patent Application No. 2019-155589 filed with the Japan Patent Office on August 28, 2019, and all the contents of that application are incorporated into this specification by reference.

[0132] Description of Reference Numerals

[0133] 1 Load sensor element

[0134] 2 substrates

[0135] 3 Inorganic layer

[0136] 4 Thin film resistor

[0137] 5 electrodes

[0138] 6. Leading lines

[0139] 7 substrate layer

[0140] 8 Thin film resistor layer

[0141] 9 Electrode Layer

[0142] 10Inorganic layers

[0143] 11 Load sensor element board

[0144] 12-unit element

[0145] 21 Covering

[0146] 22 exposed part

[0147] 41 body part

[0148] 42 Both ends

[0149] 421 electrode connection part

[0150] 422 connection part

Claims

1. A load sensor element for detecting a load, wherein: have: A substrate composed of a ceramic material or a metal material having an insulating layer on the surface; an inorganic layer having a pressure-bearing surface that bears a load and provided so as to cover a portion of a single surface of the substrate; A thin film resistor having a resistance value that changes according to a load on the inorganic layer, and having a main body portion sandwiched between the substrate and the inorganic layer, and two end portions placed on an exposed portion of the substrate that is not covered by the inorganic layer; a pair of electrodes electrically connected to both ends of the thin film resistor in a manner not covered by the inorganic layer and provided on one side of the substrate; The inorganic layer is a ceramic material or a metal material having an insulating layer on the surface; The thickness of the inorganic layer is greater than or equal to 0.3 mm and less than or equal to 5.0 mm.

2. The load sensor element of claim 1, wherein: The inorganic layer is composed of a ceramic substrate and is arranged on the main body through an adhesive layer.

3. The load sensor element according to claim 1 or 2, wherein: The substrate has a thickness of 0.3 mm or more and 5.0 mm or less.

4. The load sensor element according to any one of claims 1 to 3, wherein: The thin film resistor is made of NiCr-based material or Cr-based material.

5. The load sensor element according to any one of claims 1 to 4, wherein: The thickness of the thin film resistor is greater than 0 and less than 1 μm.

6. The load sensor element according to any one of claims 1 to 5, wherein: The main body portion is composed of a meandering pattern portion.

7. The load sensor element of claim 6, wherein: The two ends have: an electrode connecting portion provided with the pair of electrodes; A connecting portion connects the meandering pattern portion and the electrode connecting portion.

8. The load sensor element according to any one of claims 1 to 7, wherein: The substrate and the inorganic layer are both rectangular.

9. The load sensor element according to any one of claims 1 to 8, wherein: The substrate is circular. The main body portion is composed of an arc-shaped meandering pattern or an arc-shaped pattern portion along the outer shape of the substrate.

10. The load sensor element according to any one of claims 1 to 9, wherein: A positioning portion is further provided, the positioning portion being provided so as not to interfere with the main body portion and positioning the load sensor element.

11. A method for manufacturing a load sensor element according to claim 1, wherein the load sensor element detects a load, wherein: The method for manufacturing the load sensor element comprises: A step of preparing a substrate layer made of a ceramic material or a metal material having an insulating layer on the surface; The process of laying a thin film resistor layer on the substrate layer, and laying an electrode layer on the thin film resistor layer; A step of forming a plurality of electrodes by patterning the electrode layer; A step of patterning the thin film resistor layer to form a plurality of thin film resistors each having a main body and two end portions on which a pair of the electrodes are placed; A step of forming a load sensor element plate having a plurality of unit elements provided with a pair of the electrodes by laying an inorganic layer body in which a plurality of inorganic layers corresponding to the number of the body parts are continuously formed in a manner separated from the electrodes and covering the plurality of the body parts; The step of dividing the load sensor element plate into a plurality of the unit elements.

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