Accelerator pedal, steering, door, door opening and closing system

Abstract

To provide an accelerator pedal provided with a sensor with high sensitivity, and the like.SOLUTION: The accelerator pedal is an accelerator pedal for an automobile, and comprises a sensor that detects a step-in force on the accelerator pedal. The sensor has: a base material made of resin having flexibility; a functional layer formed of metal, an alloy, or a compound of metal directly on one face of the base material; and a resistor including α-Cr as a main component, and formed of a film including Cr, CrN, and Cr2N directly on one face of the functional layer. The functional layer has a function to accelerate crystal growth of the α-Cr, and deposit a film including the α-Cr as a main component. The thickness of the resistor is 0.05 μm or more and 2 μm or less. The thickness of the functional layer is 1 nm or more and 100 nm or less. The accelerator pedal detects the step-in force on the accelerator pedal as a change in the value of resistance of the resistor.SELECTED DRAWING: Figure 25

Description

[Technical Field]

[0001] The present invention relates to an accelerator pedal, steering wheel, door, and door opening / closing system of an automobile equipped with a sensor. [Background technology]

[0002] There is known a strain gauge that is attached to an object to be measured to detect strain of the object. The strain gauge has a resistor that detects strain, and the resistor is made of a material containing, for example, chromium (Cr) or nickel (Ni). The resistor is formed on a substrate made of insulating resin, for example (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-74934 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when using strain gauges on objects with high rigidity, high sensitivity is required. However, conventional strain gauges did not have sufficient sensitivity, making it difficult to use them on objects with high rigidity.

[0005] The present invention has been made in view of the above points, and has an object to provide an accelerator pedal or the like equipped with a highly sensitive sensor. [Means for solving the problem]

[0006] This accelerator pedal is an accelerator pedal for an automobile and is equipped with a sensor that detects the force applied to the accelerator pedal. The sensor has a flexible resin substrate, a functional layer formed from a metal, alloy, or metal compound directly on one side of the substrate, and a resistor formed directly on one side of the functional layer from a film containing Cr, CrN, and CrN, the resistor having α-Cr as its main component, the resistor having a thickness of 0.05 μm or more and 2 μm or less, and the functional layer having a thickness of 1 nm or more and 100 nm or less. The accelerator pedal force is detected as a change in the resistance value of the resistor. [Effects of the Invention]

[0007] According to the disclosed technology, an accelerator pedal or the like equipped with a highly sensitive sensor can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view illustrating a strain gauge according to a first embodiment. [Figure 2] 1 is a cross-sectional view illustrating a strain gauge according to a first embodiment. [Figure 3] 3A to 3C are diagrams illustrating a manufacturing process of the strain gauge according to the first embodiment. [Figure 4] 1 is a cross-sectional view illustrating a strain gauge according to a first modified example of the first embodiment. [Figure 5] FIG. 10 is a plan view illustrating a strain gauge according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view illustrating a strain gauge according to a second embodiment. [Figure 7] 10A to 10C are diagrams (part 1) illustrating a manufacturing process of the strain gauge according to the second embodiment. [Figure 8] 10A to 10C are diagrams (part 2) illustrating the manufacturing process of the strain gauge according to the second embodiment. [Figure 9]FIG. 10 is a cross-sectional view illustrating a strain gauge according to a first modified example of the second embodiment. [Figure 10] FIG. 10 is a cross-sectional view illustrating a strain gauge according to a second modification of the second embodiment. [Figure 11] FIG. 10 is a cross-sectional view illustrating a sensor module according to a third embodiment. [Figure 12] FIG. 10 is a diagram showing the results of fluorescent X-ray analysis of the functional layer. [Figure 13] FIG. 10 is a diagram showing the results of X-ray diffraction of a resistor. [Figure 14] FIG. 10 is a diagram showing the relationship between the expansion coefficient of the substrate and the internal stress of the resistor. [Figure 15] FIG. 10 is a diagram showing the relationship between the surface irregularities of a substrate and the number of pinholes in a resistor. [Figure 16] FIG. 10 is a plan view illustrating a sensor according to a fourth embodiment. [Figure 17] FIG. 10 is a cross-sectional view illustrating a sensor according to a fourth embodiment. [Figure 18] FIG. 11 is a plan view illustrating a sensor according to a fifth embodiment. [Figure 19] FIG. 10 is a cross-sectional view illustrating a sensor according to a fifth embodiment. [Figure 20] FIG. 10 is a block diagram illustrating a sensor module according to a fifth embodiment. [Figure 21] FIG. 10 is a block diagram illustrating a control device for a sensor module according to a fifth embodiment. [Figure 22] FIG. 13 is a plan view illustrating a sensor according to a first modified example of the fifth embodiment. [Figure 23] FIG. 2 is a schematic diagram illustrating an example of air flow when a vehicle is running. [Figure 24] FIG. 1 is a perspective view showing an example in which a strain gauge 3 is attached to a spoiler of an automobile. [Figure 25] FIG. 1 is a perspective view showing an example in which a strain gauge 3 is attached to an accelerator pedal of an automobile. [Figure 26] FIG. 10 is a perspective view showing a comparative example in which a dedicated sensor is attached to the steering wheel of an automobile. [Figure 27] FIG. 1 is a cross-sectional view showing an example in which a strain gauge 3 is attached to a steering wheel of an automobile. [Figure 28] FIG. 1 is a plan view showing an example in which a strain gauge 3 is attached to a steering wheel of an automobile. [Figure 29] FIG. 1 is a schematic diagram illustrating detection of a grip force of a steering wheel of an automobile. [Figure 30] FIG. 1 is a perspective view showing an example in which a strain gauge 3 is attached to a car door. [Figure 31] FIG. 1 is a cross-sectional view showing an example in which a strain gauge 3 is attached to a car door. [Figure 32] FIG. 2 is a perspective view showing an example of a six-axis force sensor having a strain gauge 3. [Figure 33] FIG. 10 is a perspective view illustrating the position where a six-axis force sensor is arranged. [Figure 34] FIG. 1 is a schematic diagram showing an example in which a strain gauge 3 is attached to a windshield wiper of an automobile. [Figure 35] FIG. 1 is a schematic diagram showing an example in which a strain gauge 3 is attached to a bumper of an automobile. [Figure 36] FIG. 1 is a schematic diagram showing an example in which strain gauges 3 are arranged near an engine and a supercharger of an automobile. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] First Embodiment FIG. 1 is a plan view illustrating a strain gauge according to a first embodiment. FIG. 2 is a cross-sectional view illustrating the strain gauge according to the first embodiment, showing a cross section along line AA in FIG. 1. Referring to FIGS. 1 and 2, the strain gauge 1 has a substrate 10, a functional layer 20, a resistor 30, a terminal portion 41, and a cover layer 60. However, the functional layer 20 and the cover layer 60 are not essential components and can be provided as needed to improve performance, etc. In FIG. 1, for the sake of convenience, only the outer edge of the cover layer 60 is shown by a dashed line in order to illustrate the resistor 30.

[0011] In this embodiment, for convenience, the side of the strain gauge 1 on which the resistor 30 of the substrate 10 is provided is referred to as the upper side or one side, and the side on which the resistor 30 is not provided is referred to as the lower side or the other side. Furthermore, the surface on which the resistor 30 of each portion is provided is referred to as the one side or upper side, and the surface on which the resistor 30 is not provided is referred to as the other side or lower side. However, the strain gauge 1 can be used upside down or positioned at any angle. Furthermore, a planar view refers to viewing an object from the normal direction of the upper surface 10a of the substrate 10, and a planar shape refers to the shape of the object viewed from the normal direction of the upper surface 10a of the substrate 10.

[0012] The substrate 10 is a flexible member that serves as a base layer for forming the resistor 30 and the like. The thickness of the substrate 10 is not particularly limited and can be appropriately selected depending on the purpose, but can be, for example, about 5 μm to 500 μm. In particular, a thickness of 5 μm to 200 μm is preferable in terms of the transferability of strain from the surface of the strain generator bonded to the lower surface of the substrate 10 via an adhesive layer or the like and dimensional stability against the environment, and a thickness of 10 μm or more is even more preferable in terms of insulation properties.

[0013] The substrate 10 can be formed from an insulating resin film such as PI (polyimide) resin, epoxy resin, PEEK (polyether ether ketone) resin, PEN (polyethylene naphthalate) resin, PET (polyethylene terephthalate) resin, PPS (polyphenylene sulfide) resin, polyolefin resin, etc. The film refers to a flexible member having a thickness of about 500 μm or less.

[0014] Here, "formed from an insulating resin film" does not prevent the base material 10 from containing fillers, impurities, etc. in the insulating resin film. The base material 10 may be formed from an insulating resin film containing fillers such as silica or alumina, for example.

[0015] The functional layer 20 is formed on the upper surface 10a of the substrate 10 as a lower layer of the resistor 30. That is, the planar shape of the functional layer 20 is substantially the same as the planar shape of the resistor 30 shown in Fig. 1. The thickness of the functional layer 20 can be, for example, about 1 nm to 100 nm.

[0016] In the present application, the functional layer refers to a layer having a function of promoting crystal growth of at least the upper layer, the resistor 30. The functional layer 20 preferably also has a function of preventing oxidation of the resistor 30 due to oxygen and moisture contained in the substrate 10, and a function of improving adhesion between the substrate 10 and the resistor 30. The functional layer 20 may also have other functions.

[0017] The insulating resin film that constitutes the substrate 10 contains oxygen and moisture, and since Cr forms a self-oxidation film, particularly when the resistor 30 contains chromium (Cr), it is effective for the functional layer 20 to have the function of preventing oxidation of the resistor 30.

[0018] The material of the functional layer 20 is not particularly limited as long as it has the function of promoting the crystal growth of at least the upper layer, the resistor 30, and can be appropriately selected depending on the purpose. For example, Cr (chromium), Ti (titanium), V (vanadium), Nb (niobium), Ta (tantalum), Ni (nickel), Y (yttrium), Zr (zirconium), Hf (hafnium), Si (silicon), C (carbon), Zn (zinc), Cu (copper), Bi (bismuth), Examples of the metal include one or more metals selected from the group consisting of Fe (iron), Mo (molybdenum), W (tungsten), Ru (ruthenium), Rh (rhodium), Re (rhenium), Os (osmium), Ir (iridium), Pt (platinum), Pd (palladium), Ag (silver), Au (gold), Co (cobalt), Mn (manganese), and Al (aluminum), an alloy of any of the metals in this group, and a compound of any of the metals in this group.

[0019] Examples of the alloys include FeCr, TiAl, FeNi, NiCr, CrCu, etc. Examples of the compounds include TiN, TaN, Si3N4, TiO2, Ta2O5, SiO2, etc.

[0020] The resistor 30 is a thin film formed in a predetermined pattern on the upper surface of the functional layer 20, and is a sensing part that generates a change in resistance value when subjected to strain. For convenience, the resistor 30 is shown in Fig. 1 with a matte finish.

[0021] The resistor 30 can be formed from, for example, a material containing Cr (chromium), a material containing Ni (nickel), or a material containing both Cr and Ni. That is, the resistor 30 can be formed from a material containing at least one of Cr and Ni. An example of a material containing Cr is a Cr mixed phase film. An example of a material containing Ni is Cu-Ni (copper-nickel). An example of a material containing both Cr and Ni is Ni-Cr (nickel-chromium).

[0022] Here, the Cr mixed phase film is a film in which Cr, CrN, CrN, etc. are mixed. The Cr mixed phase film may contain inevitable impurities such as chromium oxide. Furthermore, a portion of the material constituting the functional layer 20 may be diffused into the Cr mixed phase film. In this case, the material constituting the functional layer 20 may form a compound with nitrogen. For example, if the functional layer 20 is formed from Ti, the Cr mixed phase film may contain Ti or TiN (titanium nitride).

[0023] The thickness of resistor 30 is not particularly limited and can be appropriately selected depending on the purpose, but can be, for example, about 0.05 μm to 2 μm. In particular, a thickness of resistor 30 of 0.1 μm or more is preferable because it improves the crystallinity of the crystals constituting resistor 30 (for example, the crystallinity of α-Cr), and a thickness of 1 μm or less is even more preferable because it reduces cracks in the film constituting resistor 30 and warpage from substrate 10 caused by internal stress in the film.

[0024] By forming the resistor 30 on the functional layer 20, the resistor 30 can be formed using a stable crystalline phase, thereby improving the stability of the gauge characteristics (gauge factor, temperature coefficient of gauge factor TCS, and temperature coefficient of resistance TCR).

[0025] For example, when the resistor 30 is a Cr mixed phase film, the resistor 30 can be formed with α-Cr (alpha chromium) as the main component by providing the functional layer 20. Since α-Cr is a stable crystalline phase, the stability of the gauge characteristics can be improved.

[0026] Here, "main component" means that the target substance accounts for 50% by mass or more of all substances constituting the resistor. When the resistor 30 is a Cr mixed phase film, it is preferable that the resistor 30 contains 80% by weight or more of α-Cr in order to improve the gauge characteristics. Note that α-Cr is Cr with a bcc structure (body-centered cubic lattice structure).

[0027] Furthermore, the gauge characteristics can be improved by diffusing the metal (e.g., Ti) constituting the functional layer 20 into the Cr mixed phase film. Specifically, the gauge factor of the strain gauge 1 can be set to 10 or more, and the temperature coefficient of gauge factor TCS and the temperature coefficient of resistance TCR can be set within the range of -1000 ppm / °C to +1000 ppm / °C.

[0028] From the viewpoint of reducing warpage of the substrate 10 by making the internal stress of the resistor 30 close to zero, it is preferable that the expansion coefficient of the substrate 10 is 7 ppm / K to 20 ppm / K. The expansion coefficient of the substrate 10 can be adjusted, for example, by selecting the material of the substrate 10, selecting the material of the filler contained in the substrate 10, and adjusting the content thereof.

[0029] However, when resistor 30 is formed on substrate 10, pinholes may occur in resistor 30. If the number of pinholes occurring in resistor 30 exceeds a predetermined value, the gauge characteristics may deteriorate and the resistor may no longer function as a strain gauge. The inventors have discovered that one of the causes of pinholes occurring in resistor 30 is filler protruding from top surface 10a of substrate 10.

[0030] That is, when the substrate 10 contains a filler, a part of the filler protrudes from the upper surface 10a of the substrate 10, increasing the surface unevenness of the upper surface 10a of the substrate 10. As a result, the number of pinholes generated in the resistor 30 formed on the upper surface 10a of the substrate 10 increases, which causes deterioration of the gauge characteristics, etc.

[0031] The inventors have found that when the thickness of resistor 30 is 0.05 μm or more, if the surface roughness of upper surface 10a of substrate 10 is 15 nm or less, the number of pinholes that occur in resistor 30 can be suppressed and gauge characteristics can be maintained.

[0032] That is, when the thickness of resistor 30 is 0.05 μm or more, from the viewpoint of reducing the number of pinholes that occur in resistor 30 formed on upper surface 10a of substrate 10 and maintaining the gauge characteristics, the surface roughness of upper surface 10a of substrate 10 is preferably 15 nm or less, and even if substrate 10 contains a filler, the gauge characteristics will not deteriorate if the surface roughness is 15 nm or less. Note that the surface roughness of upper surface 10a of substrate 10 may be 0 nm.

[0033] The surface irregularities of the upper surface 10a of the substrate 10 can be reduced, for example, by heating the substrate 10. Alternatively, instead of heating the substrate 10, other methods may be used, such as a method of irradiating the upper surface 10a of the substrate 10 with laser light substantially perpendicularly to remove the convex portions, a method of moving a water cutter or the like parallel to the upper surface 10a of the substrate 10 to remove the convex portions, a method of polishing the upper surface 10a of the substrate 10 with a grindstone, or a method of applying pressure to the substrate 10 while heating it (heat press).

[0034] The surface roughness refers to the arithmetic mean roughness, and is generally expressed as Ra. The surface roughness can be measured, for example, by three-dimensional optical interferometry.

[0035] The terminal portions 41 extend from both ends of the resistor 30 and are formed in a generally rectangular shape wider than the resistor 30 in a plan view. The terminal portions 41 are a pair of electrodes for outputting a change in the resistance value of the resistor 30 caused by strain to the outside, and are connected to, for example, lead wires for external connection. For example, the resistor 30 extends from one of the terminal portions 41 while folding back in a zigzag pattern and is connected to the other terminal portion 41. The upper surface of the terminal portion 41 may be coated with a metal that has better solderability than the terminal portion 41. Although the resistor 30 and the terminal portion 41 are denoted by different reference numerals for convenience, they can be integrally formed from the same material in the same process.

[0036] The cover layer 60 is an insulating resin layer provided on the upper surface 10a of the substrate 10 so as to cover the resistor 30 and expose the terminal portions 41. By providing the cover layer 60, it is possible to prevent mechanical damage to the resistor 30. Furthermore, by providing the cover layer 60, it is possible to protect the resistor 30 from moisture and the like. Note that the cover layer 60 may be provided so as to cover the entire portion excluding the terminal portions 41.

[0037] The cover layer 60 can be formed from an insulating resin such as PI resin, epoxy resin, PEEK resin, PEN resin, PET resin, PPS resin, or composite resin (e.g., silicone resin or polyolefin resin). The cover layer 60 may contain a filler or a pigment. There are no particular restrictions on the thickness of the cover layer 60 and it can be appropriately selected depending on the purpose, but it can be, for example, about 2 μm to 30 μm.

[0038] 3A and 3B are diagrams illustrating the manufacturing process of the strain gauge according to the first embodiment, showing a cross section corresponding to that of FIG. 2. To manufacture the strain gauge 1, first, in the step shown in FIG. 3A, a substrate 10 is prepared, and a functional layer 20 is formed on the upper surface 10a of the substrate 10. The materials and thicknesses of the substrate 10 and the functional layer 20 are as described above.

[0039] The functional layer 20 can be formed in vacuum by conventional sputtering, for example, using a raw material capable of forming the functional layer 20 as a target and introducing Ar (argon) gas into a chamber. By using conventional sputtering, the functional layer 20 is formed while etching the upper surface 10a of the substrate 10 with Ar, so that the amount of the functional layer 20 formed can be minimized and an effect of improving adhesion can be obtained.

[0040] However, this is just one example of a method for forming the functional layer 20, and the functional layer 20 may be formed by other methods. For example, a method may be used in which the upper surface 10a of the substrate 10 is activated by plasma treatment using Ar or the like before forming the functional layer 20, thereby improving adhesion, and then the functional layer 20 is vacuum-formed by magnetron sputtering.

[0041] Next, in the step shown in FIG. 3( b), the resistor 30 and the terminal portion 41 are formed on the entire upper surface of the functional layer 20, and then the functional layer 20, the resistor 30, and the terminal portion 41 are patterned by photolithography into the planar shape shown in FIG. 1. The material and thickness of the resistor 30 and the terminal portion 41 are as described above. The resistor 30 and the terminal portion 41 can be integrally formed using the same material. The resistor 30 and the terminal portion 41 can be formed as films by, for example, magnetron sputtering using a target material capable of forming the resistor 30 and the terminal portion 41. The resistor 30 and the terminal portion 41 may also be formed as films using reactive sputtering, vapor deposition, arc ion plating, pulsed laser deposition, or the like instead of magnetron sputtering.

[0042] There are no particular limitations on the combination of the material of the functional layer 20 and the materials of the resistor 30 and terminal portion 41, and these can be selected appropriately depending on the purpose. For example, it is possible to use Ti for the functional layer 20, and to form a Cr mixed phase film containing α-Cr (alpha chromium) as the main component for the resistor 30 and terminal portion 41.

[0043] In this case, for example, the resistor 30 and the terminal portion 41 can be formed by magnetron sputtering using a target made of a material capable of forming a Cr mixed phase film and introducing Ar gas into a chamber. Alternatively, the resistor 30 and the terminal portion 41 can be formed by reactive sputtering using pure Cr as a target and introducing an appropriate amount of nitrogen gas into a chamber together with Ar gas.

[0044] In these methods, the Ti functional layer 20 defines the growth plane of the Cr mixed-phase film, allowing the formation of a Cr mixed-phase film primarily composed of α-Cr, which has a stable crystal structure. Furthermore, the Ti constituting the functional layer 20 diffuses into the Cr mixed-phase film, improving the gauge characteristics. For example, the gauge factor of the strain gauge 1 can be set to 10 or more, and the temperature coefficient of gauge factor (TCS) and temperature coefficient of resistance (TCR) can be set within the ranges of -1000 ppm / °C to +1000 ppm / °C.

[0045] When the resistor 30 is a Cr mixed phase film, the functional layer 20 made of Ti has all of the following functions: promoting crystal growth of the resistor 30, preventing oxidation of the resistor 30 due to oxygen and moisture contained in the substrate 10, and improving adhesion between the substrate 10 and the resistor 30. The same applies when Ta, Si, Al, or Fe is used as the functional layer 20 instead of Ti.

[0046] Next, in the step shown in FIG. 3(c), a cover layer 60 is formed on the upper surface 10a of the substrate 10 to cover the resistor 30 and expose the terminal portions 41. The material and thickness of the cover layer 60 are as described above. The cover layer 60 can be produced, for example, by laminating a semi-cured thermosetting insulating resin film on the upper surface 10a of the substrate 10 so as to cover the resistor 30 and expose the terminal portions 41, and then heating and curing the film. The cover layer 60 may also be produced by applying a liquid or paste-like thermosetting insulating resin to the upper surface 10a of the substrate 10 so as to cover the resistor 30 and expose the terminal portions 41, and then heating and curing the resin. The strain gauge 1 is completed through the steps described above.

[0047] In this way, by providing the functional layer 20 below the resistor 30, it is possible to promote crystal growth of the resistor 30, and to produce a resistor 30 consisting of a stable crystalline phase. As a result, it is possible to improve the stability of the gauge characteristics of the strain gauge 1. Furthermore, by diffusing the material that constitutes the functional layer 20 into the resistor 30, it is possible to improve the gauge characteristics of the strain gauge 1.

[0048] <Modification 1 of the First Embodiment> In the first modification of the first embodiment, an example of a strain gauge in which an insulating layer is provided under a cover layer is shown. Note that in the first modification of the first embodiment, the description of the same components as those in the already described embodiments may be omitted.

[0049] Fig. 4 is a cross-sectional view illustrating a strain gauge according to Modification 1 of the first embodiment, showing a cross section corresponding to Fig. 2. Referring to Fig. 4, strain gauge 1A differs from strain gauge 1 (see Figs. 1, 2, etc.) in that an insulating layer 50 is provided below cover layer 60. Note that cover layer 60 may be provided so as to cover the entire portion excluding terminal portions 41.

[0050] The insulating layer 50 is provided on the upper surface 10a of the substrate 10 so as to cover the resistor 30 and expose the terminal portion 41. The cover layer 60 can be provided so as to cover, for example, part of the side surfaces and the upper surface of the insulating layer 50.

[0051] The material of the insulating layer 50 is not particularly limited and can be selected appropriately depending on the purpose as long as it has a higher resistance than the resistor 30 and the cover layer 60, and can be, for example, an oxide or nitride of Si, W, Ti, Ta, etc. The thickness of the insulating layer 50 is not particularly limited and can be selected appropriately depending on the purpose, and can be, for example, about 0.05 μm to 1 μm.

[0052] The method for forming the insulating layer 50 is not particularly limited and can be selected appropriately depending on the purpose, but for example, vacuum processes such as sputtering and chemical vapor deposition (CVD) methods, or solution processes such as spin coating and sol-gel methods can be used.

[0053] In this way, by providing the insulating layer 50 below the cover layer 60, it is possible to improve the insulating properties and environmental sealing properties compared to the case where only the cover layer 60 is provided. Therefore, the insulating layer 50 can be provided as appropriate according to the required specifications of insulating properties and environmental sealing properties.

[0054] Second Embodiment In the second embodiment, an example of a strain gauge in which electrodes have a laminated structure is shown. Note that in the second embodiment, the description of the same components as those in the already described embodiments may be omitted.

[0055] Fig. 5 is a plan view illustrating a strain gauge according to the second embodiment. Fig. 6 is a cross-sectional view illustrating the strain gauge according to the second embodiment, taken along line BB in Fig. 5. Referring to Figs. 5 and 6, the strain gauge 2 includes an electrode 40A formed by stacking multiple layers. Note that the cover layer 60 may be provided so as to cover the entire portion excluding the electrode 40A.

[0056] Electrode 40A has a laminated structure in which multiple metal layers are stacked. Specifically, electrode 40A has terminal portions 41 extending from both ends of resistor 30, metal layer 42 formed on the upper surface of terminal portion 41, metal layer 43 formed on the upper surface of metal layer 42, and metal layer 44 formed on the upper surface of metal layer 43. Metal layer 43 is a typical example of a first metal layer according to the present invention, and metal layer 44 is a typical example of a second metal layer according to the present invention.

[0057] The material of the metal layer 42 is not particularly limited and can be selected appropriately depending on the purpose, for example, Cu (copper). The thickness of the metal layer 42 is not particularly limited and can be selected appropriately depending on the purpose, for example, it can be about 0.01 μm to 1 μm.

[0058] The material of the metal layer 43 is preferably Cu, a Cu alloy, Ni, or a Ni alloy. The thickness of the metal layer 43 is determined taking into consideration the solderability to the electrode 40A, and is preferably 1 μm or more, more preferably 3 μm or more. By using Cu, a Cu alloy, Ni, or a Ni alloy as the material of the metal layer 43 and making the thickness of the metal layer 43 1 μm or more, solder erosion is improved. Furthermore, by using Cu, a Cu alloy, Ni, or a Ni alloy as the material of the metal layer 43 and making the thickness of the metal layer 43 3 μm or more, solder erosion is further improved. Note that, for ease of electroplating, the thickness of the metal layer 43 is preferably 30 μm or less.

[0059] Here, solder erosion refers to the material that constitutes electrode 40A dissolving in the solder that is joined to electrode 40A, causing a decrease in the thickness of electrode 40A or even the disappearance of electrode 40A. If solder erosion occurs, there is a risk that the adhesive strength and tensile strength between electrode 40A and the lead wire or the like joined to electrode 40A may decrease, so it is preferable that solder erosion does not occur.

[0060] The material of the metal layer 44 can be selected from materials having better solder wettability than the metal layer 43. For example, if the material of the metal layer 43 is Cu, a Cu alloy, Ni, or a Ni alloy, Au (gold) can be used as the material of the metal layer 44. By coating the surface of Cu, a Cu alloy, Ni, or a Ni alloy with Au, oxidation and corrosion of the Cu, Cu alloy, Ni, or Ni alloy can be prevented and good solder wettability can be obtained. The same effect can be achieved by using Pt (platinum) instead of Au as the material of the metal layer 44. There are no particular limitations on the thickness of the metal layer 44 and it can be appropriately selected depending on the purpose, but it can be, for example, about 0.01 μm to 1 μm.

[0061] In plan view, the terminal portion 41 is exposed around the laminated portion of the metal layers 42, 43, and 44, but the terminal portion 41 may have the same planar shape as the laminated portion of the metal layers 42, 43, and 44.

[0062] 7 and 8 are diagrams illustrating the manufacturing process of a strain gauge according to the second embodiment, showing a cross section corresponding to FIG. 6. To manufacture the strain gauge 2, first, a process similar to that of the first embodiment shown in FIG. 3(a) is performed, and then, in the process shown in FIG. 7(a), a metal layer 300 is formed on the upper surface of the functional layer 20. The metal layer 300 is a layer that will ultimately be patterned to become the resistor 30 and the terminal portion 41. Therefore, the material and thickness of the metal layer 300 are the same as those of the resistor 30 and the terminal portion 41 described above.

[0063] The metal layer 300 can be formed by, for example, magnetron sputtering using a target made of a raw material capable of forming the metal layer 300. Instead of magnetron sputtering, the metal layer 300 may be formed by reactive sputtering, vapor deposition, arc ion plating, pulsed laser deposition, or the like.

[0064] Next, in the step shown in FIG. 7(b), a seed layer 420 that will become the metal layer 42 is formed so as to cover the upper surface of the metal layer 300 by, for example, sputtering or electroless plating.

[0065] 7(c), a photosensitive resist 800 is formed on the entire upper surface of the seed layer 420, and is exposed and developed to form openings 800x that expose regions where the electrodes 40A will be formed. As the resist 800, for example, a dry film resist or the like can be used.

[0066] 7(d), for example, a metal layer 43 is formed on the seed layer 420 exposed in the opening 800x by electroplating using the seed layer 420 as a power supply path, and a metal layer 44 is further formed on the metal layer 43. Electroplating is advantageous in that it has a high tact time and can form a low-stress electroplated layer as the metal layer 43. By forming a thick electroplated layer with low stress, warping of the strain gauge 2 can be prevented. Alternatively, the metal layer 44 may be formed on the metal layer 43 by electroless plating.

[0067] When forming the metal layer 44, the side surfaces of the metal layer 43 are covered with the resist 800, so the metal layer 44 is formed only on the top surface of the metal layer 43, and not on the side surfaces.

[0068] Next, in the step shown in Fig. 8(a), the resist 800 shown in Fig. 7(d) is removed. The resist 800 can be removed, for example, by immersing it in a solution that can dissolve the material of the resist 800.

[0069] 8(b), a photosensitive resist 810 is formed on the entire upper surface of the seed layer 420, and is exposed to light and developed to be patterned into a planar shape similar to that of the resistor 30 and the terminal portion 41 in Fig. 5. For example, a dry film resist or the like can be used as the resist 810.

[0070] 8(c), the resist 810 is used as an etching mask to remove the functional layer 20, metal layer 300, and seed layer 420 exposed from the resist 810, thereby forming the functional layer 20, resistor 30, and terminal portion 41 having the planar shapes shown in FIG. 5. For example, unnecessary portions of the functional layer 20, metal layer 300, and seed layer 420 can be removed by wet etching. At this point, the seed layer 420 is formed on the resistor 30.

[0071] 8(d), the metal layer 43 and the metal layer 44 are used as an etching mask to remove unnecessary seed layer 420 exposed from the metal layer 43 and the metal layer 44, thereby forming the metal layer 42. For example, the unnecessary seed layer 420 can be removed by wet etching using an etching solution that etches the seed layer 420 but does not etch the functional layer 20 and the resistor 30.

[0072] After the step shown in Figure 8(d), in the same manner as the step shown in Figure 3(c), a cover layer 60 is formed on the upper surface 10a of the substrate 10 to cover the resistor 30 and expose the electrode 40A, thereby completing the strain gauge 2.

[0073] In this way, electrode 40A has metal layer 43 formed on terminal portion 41, which is made of a thick film (1 μm or more) of Cu, Cu alloy, Ni, or Ni alloy, and further has metal layer 44 formed on the outermost surface, which is made of a material (Au or Pt) that has better solder wettability than metal layer 43. This makes it possible to prevent solder erosion and improve solder wettability.

[0074] <Modification 1 of the Second Embodiment> In Modification 1 of the second embodiment, an example of an electrode having a layer structure different from that of the second embodiment is shown. Note that in Modification 1 of the second embodiment, the description of the same components as those in the already described embodiments may be omitted.

[0075] Fig. 9 is a cross-sectional view illustrating a strain gauge according to Modification 1 of the second embodiment, showing a cross section corresponding to Fig. 6. Referring to Fig. 9, strain gauge 2A differs from strain gauge 2 (see Fig. 6, etc.) in that electrode 40A is replaced with electrode 40B. Also, strain gauge 2A differs from strain gauge 2 (see Fig. 6, etc.) in that cover layer 60 is provided so as to cover substantially the entire portion except for electrode 40B.

[0076] Electrode 40B has a laminated structure in which multiple metal layers are stacked. Specifically, electrode 40B has terminal portions 41 extending from both ends of resistor 30, metal layer 42 formed on the upper surface of terminal portion 41, metal layer 43 formed on the upper surface of metal layer 42, metal layer 45 formed on the upper surface of metal layer 43, and metal layer 44 formed on the upper surface of metal layer 45. In other words, electrode 40B has a structure in which metal layer 45 is provided between metal layer 43 and metal layer 44 of electrode 40A.

[0077] The material of the metal layer 45 is not particularly limited and can be selected appropriately depending on the purpose, but for example, Ni can be used. NiP (nickel phosphorus) or Pd may be used instead of Ni. The metal layer 45 may also be Ni / Pd (a metal layer formed by laminating a Ni layer and a Pd layer in this order). The thickness of the metal layer 45 is not particularly limited and can be selected appropriately depending on the purpose, but can be, for example, about 1 μm to 2 μm.

[0078] The metal layer 45 can be formed on the metal layer 43 in the step shown in FIG. 7(d) by, for example, electrolytic plating using the seed layer 420 as a power supply path.

[0079] In this way, the number of layers of the electrodes is not particularly limited, and may be increased as necessary. In this case, too, a metal layer 43 made of a thick film (1 μm or more) of Cu, a Cu alloy, Ni, or a Ni alloy is formed on the terminal portion 41, and a metal layer 44 made of a material (Au or Pt) with better solder wettability than the metal layer 43 is further formed as the outermost layer. Therefore, as in the second embodiment, solder erosion can be prevented and solder wettability can be improved.

[0080] <Modification 2 of the Second Embodiment> Modification 2 of the second embodiment shows another example of an electrode having a layer structure different from that of the second embodiment. Note that in Modification 2 of the second embodiment, the description of the same components as those in the already described embodiment may be omitted.

[0081] Fig. 10 is a cross-sectional view illustrating a strain gauge according to Modification 2 of the second embodiment, showing a cross section corresponding to Fig. 6. Referring to Fig. 10, strain gauge 2B differs from strain gauge 2A (see Fig. 9) in that electrode 40B is replaced with electrode 40C. Also, strain gauge 2B differs from strain gauge 2 (see Fig. 6, etc.) in that cover layer 60 is provided so as to cover substantially the entire portion except for electrode 40C.

[0082] The electrode 40C has a laminated structure in which multiple metal layers are stacked. Specifically, the electrode 40C includes terminal portions 41 extending from both ends of the resistor 30, a metal layer 42 formed on the upper surface of the terminal portion 41, a metal layer 43 formed on the upper surface of the metal layer 42, a metal layer 45A formed on the upper and side surfaces of the metal layer 43 and the side surfaces of the metal layer 42, and a metal layer 44A formed on the upper and side surfaces of the metal layer 45A. The material and thickness of the metal layers 44A and 45A may be the same as those of the metal layers 44 and 45, for example. The metal layer 44A is a representative example of a second metal layer according to the present invention.

[0083] To form the electrode 40C, first, in the step shown in Fig. 7(d), for example, a metal layer 43 is formed by electrolytic plating using the seed layer 420 as a power supply path, and then the resist 800 is removed in the same manner as in the step shown in Fig. 8(a) without forming a metal layer 44. Thereafter, the same steps as in Figs. 8(b) to 8(d) are performed. Thereafter, for example, a metal layer 45A can be formed on the upper and side surfaces of the metal layer 43 and the side surfaces of the metal layer 42 by electroless plating. Furthermore, for example, a metal layer 44A can be formed on the upper and side surfaces of the metal layer 45A by electroless plating.

[0084] In this way, the electrode can be fabricated by appropriately combining electrolytic plating and electroless plating. In the structure of electrode 40C, metal layer 43 made of a thick film (1 μm or more) of Cu, Cu alloy, Ni, or Ni alloy is formed on terminal portion 41, and metal layer 44A made of a material (Au or Pt) with better solder wettability than metal layer 43 is further formed as the outermost layer. However, outermost metal layer 44A is formed not only on the top surface of metal layer 43 but also on the side surfaces of metal layers 42 and 43 via metal layer 45A. Therefore, compared to electrodes 40A and 40B, the effect of preventing oxidation and corrosion of Cu, Cu alloy, Ni, or Ni alloy constituting metal layer 43 can be further improved, and solder wettability can be further improved.

[0085] The same effect can be obtained by forming metal layer 44A directly on the upper and side surfaces of metal layer 43 and the side surfaces of metal layer 42 without forming metal layer 45A. That is, it is sufficient that metal layer 44A directly or indirectly covers the upper and side surfaces of metal layer 43 and the side surfaces of metal layer 42.

[0086] Third Embodiment In the third embodiment, an example of a sensor module using a strain gauge will be described. Note that in the third embodiment, the description of the same components as those in the embodiments already described may be omitted.

[0087] Fig. 11 is a cross-sectional view illustrating a sensor module according to the third embodiment, showing a cross section corresponding to Fig. 2. Referring to Fig. 11, the sensor module 5 has a strain gauge 1, a flexure element 110, and an adhesive layer 120. The cover layer 60 may be provided so as to cover the entire portion except for the terminal portion 41.

[0088] In the sensor module 5, the upper surface 110a of the flexure element 110 is fixed to the lower surface 10b of the substrate 10 via an adhesive layer 120. The flexure element 110 is made of, for example, a metal such as Fe, SUS (stainless steel), or Al, or a resin such as PEEK, and is an object that deforms (generates strain) in response to an applied force. The strain gauge 1 can detect the strain generated in the flexure element 110 as a change in the resistance value of the resistor 30.

[0089] The adhesive layer 120 is not particularly limited and can be selected appropriately depending on the purpose as long as it has the function of bonding the strain gauge 1 and the flexure element 110 together, and can be made of, for example, epoxy resin, modified epoxy resin, silicone resin, modified silicone resin, urethane resin, modified urethane resin, etc. Materials such as bonding sheets can also be used. The thickness of the adhesive layer 120 is not particularly limited and can be selected appropriately depending on the purpose, and can be, for example, about 0.1 μm to 50 μm.

[0090] To manufacture the sensor module 5, after fabricating the strain gauge 1, for example, one of the above materials to become the adhesive layer 120 is applied to the lower surface 10b of the substrate 10 and / or the upper surface 110a of the flexure element 110. Then, the lower surface 10b of the substrate 10 is placed opposite the upper surface 110a of the flexure element 110, and the strain gauge 1 is placed on the flexure element 110 with the applied material sandwiched between them. Alternatively, a bonding sheet may be sandwiched between the flexure element 110 and the substrate 10.

[0091] Next, the strain gauge 1 is heated to a predetermined temperature while being pressed against the flexure element 110, and the applied material is cured to form the adhesive layer 120. This bonds the upper surface 110a of the flexure element 110 to the lower surface 10b of the substrate 10 via the adhesive layer 120, completing the sensor module 5. The sensor module 5 can be used to measure, for example, load, pressure, torque, acceleration, etc.

[0092] In the sensor module 5, the strain gauge 1 may be replaced with the strain gauge 1A, 2, 2A, or 2B.

[0093] [Example 1] First, as a preliminary experiment, a Ti film was vacuum-deposited as the functional layer 20 on the upper surface 10a of a substrate 10 made of a 25 μm-thick polyimide resin by conventional sputtering. At this time, five samples were prepared by depositing Ti films with different film thicknesses.

[0094] Next, X-ray fluorescence (XRF) analysis was performed on the five samples produced, and the results shown in Figure 12 were obtained. The presence of Ti was confirmed from the X-ray peaks in Figure 12, and the X-ray intensity of each sample at the X-ray peak confirmed that the film thickness of the Ti film could be controlled in the range of 1 nm to 100 nm.

[0095] Next, in Example 1, a 3 nm thick Ti film was vacuum-formed as the functional layer 20 by conventional sputtering on the upper surface 10a of the substrate 10 made of polyimide resin and having a thickness of 25 μm.

[0096] Next, a Cr mixed phase film was formed as the resistor 30 and terminal portion 41 on the entire upper surface of the functional layer 20 by magnetron sputtering, and then the functional layer 20, resistor 30, and terminal portion 41 were patterned by photolithography as shown in FIG.

[0097] In Comparative Example 1, a Cr mixed phase film was formed as a resistor 30 and terminal portion 41 by magnetron sputtering on the upper surface 10a of a substrate 10 made of a 25 μm thick polyimide resin without forming a functional layer 20, and then patterned by photolithography as shown in Fig. 1. Note that the film formation conditions for the resistor 30 and terminal portion 41 were all the same in the sample of Example 1 and the sample of Comparative Example 1.

[0098] Next, X-ray diffraction (XRD) evaluation was performed on the sample of Example 1 and the sample of Comparative Example 1, and the results shown in Fig. 13 were obtained. Fig. 13 shows X-ray diffraction patterns in the 2θ diffraction angle range of 36 to 48 degrees, and the diffraction peak of Example 1 is shifted to the right compared to the diffraction peak of Comparative Example 1. In addition, the diffraction peak of Example 1 is higher than the diffraction peak of Comparative Example 1.

[0099] The diffraction peak of Example 1 is located near the diffraction line of α-Cr (110), and it is thought that the provision of the functional layer 20 made of Ti promoted the crystal growth of α-Cr, resulting in the formation of a Cr mixed phase film containing α-Cr as the main component.

[0100] Next, a plurality of samples of Example 1 and Comparative Example 1 were prepared and the gauge characteristics were measured. As a result, the gauge factor of each sample of Example 1 was 14 to 16, whereas the gauge factor of each sample of Comparative Example 1 was less than 10.

[0101] Furthermore, while the gauge factor temperature coefficient TCS and the temperature coefficient of resistance TCR of each sample in Example 1 were within the range of -1000 ppm / °C to +1000 ppm / °C, the gauge factor temperature coefficient TCS and the temperature coefficient of resistance TCR of each sample in Comparative Example 1 were not within the range of -1000 ppm / °C to +1000 ppm / °C.

[0102] In this way, by providing the functional layer 20 made of Ti, the crystal growth of α-Cr is promoted to form a Cr mixed phase film mainly composed of α-Cr, and a strain gauge was fabricated with a gauge factor of 10 or more and a temperature coefficient of gauge factor TCS and temperature coefficient of resistance TCR in the range of -1000 ppm / °C to +1000 ppm / °C. It is believed that the diffusion effect of Ti into the Cr mixed phase film contributes to the improvement of the gauge characteristics.

[0103] [Example 2] In Example 2, multiple substrates 10 made of 25 μm thick polyimide resin with different expansion coefficients were prepared, and when a Cr mixed phase film was formed as the resistor 30, the relationship between the expansion coefficient of the substrate 10 and the internal stress of the resistor 30 was investigated, and the results shown in Figure 14 were obtained.

[0104] The internal stress of resistor 30 was estimated by measuring the warpage of the evaluation sample and using Stoney's equation shown in formula (1). As can be seen from formula (1), the internal stress of resistor 30 shown in Fig. 14 is a value per unit thickness and does not depend on the thickness of resistor 30.

[0105]

number

[0106] 14, by setting the expansion coefficient of the substrate 10 within the range of 7 ppm / K to 20 ppm / K, the internal stress of the resistor 30 can be kept within the range of ±0.4 GPa. Here, ±0.4 GPa is the value at which the strain gauge 1 is warped to the limit of its functionality, and was determined experimentally by the inventors.

[0107] In other words, if the expansion coefficient of the substrate 10 is outside the range of 7 ppm / K to 20 ppm / K, the internal stress of the resistor 30 will exceed the range of ±0.4 GPa, causing the warping of the strain gauge 1 to increase and preventing it from functioning as a strain gauge. Therefore, the expansion coefficient of the substrate 10 must be within the range of 7 ppm / K to 20 ppm / K. Note that the material of the substrate 10 does not necessarily have to be polyimide resin.

[0108] By selecting the material of the substrate 10, selecting the material of the filler contained in the substrate 10 and adjusting the content, the expansion coefficient of the substrate 10 can be set within the range of 7 ppm / K to 20 ppm / K.

[0109] In this way, by setting the expansion coefficient of the substrate 10 within the range of 7 ppm / K to 20 ppm / K, the difference in the expansion rates between the substrate 10 and the resistor 30 and other factors can be absorbed, and the internal stress of the resistor 30 can be kept within the range of ±0.4 GPa. As a result, warping of the strain gauge 1 is reduced, and the strain gauge 1 can function stably while maintaining good gauge characteristics.

[0110] [Example 3] In Example 3, multiple substrates 10 were prepared, each made of a 25 μm thick polyimide resin containing a filler. Three samples were prepared: one unheated sample, one heat-treated at 100° C., one heat-treated at 200° C., and one heat-treated at 300° C. After returning to room temperature, the surface irregularities of the upper surface 10a of each substrate 10 were measured by three-dimensional optical interferometry.

[0111] Next, a resistor 30 having a thickness of 0.05 μm was formed on the upper surface 10 a of each substrate 10 by magnetron sputtering, and patterned by photolithography as shown in FIG. 1. Thereafter, the number of pinholes generated in the resistor 30 was measured by an optical transmission method in which light was transmitted from the back surface of the sample.

[0112] Next, based on the measurement results, the relationship between the surface irregularities of the upper surface 10a of the substrate 10 and the number of pinholes that occur in the resistor 30 is summarized in Fig. 15. Note that the bar graph in Fig. 15 shows the surface irregularities, and the line graph shows the number of pinholes. Also, 100°C, 200°C, and 300°C on the horizontal axis show the temperatures at which the substrate 10 was heat-treated, and "untreated" indicates that no heat treatment was performed.

[0113] FIG. 15 shows that by heat-treating the substrate 10 at a temperature between 100°C and 300°C, the surface irregularities on the upper surface 10a of the substrate 10 are reduced to 15 nm or less, approximately half of the untreated value, and as a result, the number of pinholes in the resistor 30 is dramatically reduced to approximately one-seventh of the original value. However, considering the heat resistance temperature of polyimide resin, heat treatment at temperatures above 250°C may cause deterioration or degradation. Therefore, it is preferable to perform the heat treatment at a temperature between 100°C and 250°C. The reduction in surface irregularities due to heat treatment is thought to be due to the polyimide resin constituting the substrate 10 incorporating the filler during thermal shrinkage caused by the heat treatment.

[0114] 15 (approximately 140) is at a level that deteriorates the gauge characteristics, but the number of pinholes after heat treatment (approximately 20) is at a level that does not adversely affect the gauge characteristics. In other words, when resistor 30 having a film thickness of 0.05 μm is used, it has been confirmed that the number of pinholes generated in resistor 30 can be reduced to a level that does not adversely affect the gauge characteristics by setting the surface roughness of upper surface 10a of substrate 10 to 15 nm or less.

[0115] It goes without saying that even when a resistor 30 having a film thickness of more than 0.05 μm is used, the number of pinholes generated in the resistor 30 can be reduced to a level that does not adversely affect the gauge characteristics by setting the surface roughness of the upper surface 10a of the substrate 10 to 15 nm or less. That is, when a resistor 30 having a film thickness of 0.05 μm or more is used, by setting the surface roughness of the upper surface 10a of the substrate 10 to 15 nm or less, the number of pinholes generated in the resistor 30 can be reduced to a level that does not adversely affect the gauge characteristics.

[0116] In this way, by subjecting the substrate 10 to heat treatment, it is possible to reduce the surface roughness of the upper surface 10a of the substrate 10 to 15 nm or less, thereby significantly reducing the number of pinholes that occur in resistor 30 with a film thickness of 0.05 μm or more. As a result, the strain gauge 1 can function stably while maintaining good gauge characteristics.

[0117] In order to reduce the number of pinholes that occur in resistor 30, it is important to reduce the surface irregularities of upper surface 10a of substrate 10, but the method for reducing the surface irregularities is not important. Although the method for reducing the surface irregularities by performing a heat treatment has been described above, the present invention is not limited to this, and any method may be used as long as it can reduce the surface irregularities of upper surface 10a of substrate 10.

[0118] The surface unevenness of the upper surface 10a of the substrate 10 can be reduced by, for example, irradiating the upper surface 10a of the substrate 10 with laser light approximately perpendicular to the substrate 10 to remove the convex portions, moving a water cutter or the like parallel to the substrate 10 to remove the convex portions, polishing the upper surface 10a of the substrate 10 with a grinding stone, or applying pressure to the substrate 10 while heating it (heat press).

[0119] Furthermore, reducing the surface unevenness of the upper surface 10a of the substrate 10 is important to reduce the number of pinholes that occur in the resistor 30. This is not necessarily limited to surface unevenness caused by the presence of filler; reducing surface unevenness that is not caused by the presence of filler using the various methods described above is also effective. For example, if the surface unevenness of the substrate 10 that does not contain filler is greater than 15 nm, the number of pinholes that occur in a resistor 30 with a film thickness of 0.05 μm or more can be reduced to a level that does not adversely affect the gauge characteristics by using the various methods described above to reduce the surface unevenness of the upper surface 10a of the substrate 10 to 15 nm or less.

[0120] [Example 4] 7 and 8 was modified to resemble Variation 1 of the second embodiment to fabricate a strain gauge 2A equipped with an electrode 40B, and the presence or absence of solder erosion was confirmed. Specifically, Cu was used for metal layers 42 and 43, NiP was used for metal layer 45, and Au was used for metal layer 44, and 10 types of samples were fabricated (Samples No. 1 to No. 10) with different thicknesses of each metal layer, and the presence or absence of solder erosion was confirmed.

[0121] The results are shown in Table 1. In Table 1, a film thickness of "0" indicates that the metal layer was not formed. Also, "x" indicates that solder erosion occurred during the first soldering. Also, "o" indicates that no solder erosion occurred during the first soldering, but some solder erosion occurred during the second soldering (assuming solder rework, etc.). Also, "◎" indicates that no solder erosion occurred during either the first or second soldering.

[0122] [Table 1] As shown in Table 1, it was confirmed that solder erosion was improved by increasing the Cu thickness to 1 μm or more, and that solder erosion was further improved by increasing the Cu thickness to 3 μm or more. Furthermore, the results of Samples 1 and 5 confirmed that the presence or absence of solder erosion depends only on the Cu thickness, and not on the presence or absence of NiP or Au. However, as mentioned above, a metal layer made of Au or an equivalent material (such as Pt) is necessary to prevent solder erosion and improve solder wettability.

[0123] Fourth Embodiment The fourth embodiment will show an example of a sensor having a structure different from that of the first embodiment. Note that in the fourth embodiment, the description of the same components as those in the embodiments already described may be omitted.

[0124] Fig. 16 is a plan view illustrating a sensor according to the fourth embodiment, and Fig. 17 is a cross-sectional view illustrating the sensor according to the fourth embodiment, taken along line CC in Fig. 16.

[0125] 16 and 17, the sensor 6A is an assembly of individual sensors 70 (strain gauges). In the present embodiment, as an example, the sensor 6A has six individual sensors 70, but the number of individual sensors 70 is not limited to six.

[0126] The sensor 6A has a substrate 10 common to each of the individual sensors 70, and a resistor 30 and a terminal portion 41 provided for each of the individual sensors 70. The individual sensors 70 are arranged on one side of the same substrate 10. The characteristics of the individual sensors 70 are similar to those of the strain gauge 1.

[0127] The cover layer 60 described in the first embodiment may be provided on the upper surface 10a of the substrate 10 so as to cover the resistor 30 of each individual sensor 70 and expose the terminal portion 41. By providing the cover layer 60, it is possible to prevent mechanical damage, etc. from occurring to the resistor 30 of each individual sensor 70. Furthermore, by providing the cover layer 60, it is possible to protect the resistor 30 of each individual sensor 70 from moisture, etc. Note that the cover layer 60 may be provided so as to cover the entire portion except for the terminal portion 41.

[0128] The sensor 6A may be attached to the surface of the object to be measured, or may be embedded in the object to be measured, for example.

[0129] In this way, the state of the object to be measured may be detected using the sensor 6A, which is an assembly of individual sensors 70 (strain gauges). This may be more convenient than using multiple individual strain gauges 1. The state of the object to be measured may be strain, expansion, contraction, deformation, etc. of the object to be measured.

[0130] Fifth Embodiment In the fifth embodiment, an example of a sensor capable of acquiring three-dimensional information will be described. Note that in the fifth embodiment, the description of the same components as those in the embodiments already described may be omitted.

[0131] Fig. 18 is a plan view illustrating a sensor according to the fifth embodiment, and Fig. 19 is a cross-sectional view illustrating the sensor according to the fifth embodiment, taken along line DD in Fig. 18.

[0132] Referring to FIGS. 18 and 19, the sensor 6B has a resistor 30B and terminal portions 41B and 42B.

[0133] The resistor 30B includes a plurality of resistive portions 31B and 32B laminated via the substrate 10. That is, the resistor 30B is a collective term for the plurality of resistive portions 31B and 32B, and will be referred to as the resistor 30B when there is no need to particularly distinguish between the resistive portions 31B and 32B. For convenience, the resistive portions 31B and 32B are shown with a matte finish in FIG. 18.

[0134] The plurality of resistor portions 31B are thin films arranged in the Y direction at predetermined intervals on the upper surface 10a of the substrate 10, with their longitudinal directions facing the X direction. The plurality of resistor portions 32B are thin films arranged in the X direction at predetermined intervals on the lower surface 10b of the substrate 10, with their longitudinal directions facing the Y direction. However, the plurality of resistor portions 31B and the plurality of resistor portions 32B do not need to be orthogonal to each other in a plan view, as long as they intersect.

[0135] The width of the resistor 30B is not particularly limited and can be selected appropriately depending on the purpose, and can be, for example, approximately 0.1 μm to 1000 μm (1 mm). The pitch between adjacent resistors 30B is not particularly limited and can be selected appropriately depending on the purpose, and can be, for example, approximately 1 mm to 100 mm. Although FIGS. 18 and 19 show ten resistor portions 31B and ten resistor portions 32B, the numbers of resistor portions 31B and 32B can be changed appropriately as needed. The material, thickness, manufacturing method, etc. of the resistor 30B can be the same as those of the resistor 30.

[0136] The terminal portions 41B extend from both ends of each of the resistor portions 31B on the upper surface 10a of the substrate 10 and are formed in a generally rectangular shape wider than the resistor portions 31B in a plan view. The terminal portions 41B are a pair of electrodes for outputting to the outside a change in the resistance value of the resistor portion 31B according to the state of the object to be measured, and are joined to, for example, a flexible substrate or lead wire for external connection. The upper surface of the terminal portion 41B may be covered with a metal that has better solderability than the terminal portion 41B. Note that, although the resistor portions 31B and the terminal portions 41B are denoted by different reference numerals for convenience, they can be integrally formed from the same material in the same process.

[0137] The terminal portions 42B extend from both ends of each of the resistor portions 32B on the lower surface 10b of the substrate 10 and are formed in a generally rectangular shape wider than the resistor portions 32B in a plan view. The terminal portions 42B are a pair of electrodes for outputting to the outside a change in the resistance value of the resistor portion 32B corresponding to the state of the object to be measured, and are joined to, for example, a flexible substrate or lead wire for external connection. The upper surface of the terminal portion 42B may be covered with a metal that has better solderability than the terminal portion 42B. Note that, although the resistor portions 32B and the terminal portions 42B are denoted by different reference numerals for convenience, they can be integrally formed from the same material in the same process.

[0138] It is also possible to provide through-holes that penetrate the base material 10, and to concentrate the terminal portions 41B and 42B on the upper surface 10a side or the lower surface 10b side of the base material 10.

[0139] The cover layer 60 described in the first embodiment may be provided on the upper surface 10a of the substrate 10 so as to cover the resistor portion 31B and expose the terminal portion 41B. The cover layer 60 described in the first embodiment may also be provided on the lower surface 10b of the substrate 10 so as to cover the resistor portion 32B and expose the terminal portion 42B. By providing the cover layer 60, mechanical damage to the resistor portions 31B and 32B can be prevented. Furthermore, by providing the cover layer 60, the resistor portions 31B and 32B can be protected from moisture and the like. The cover layer 60 may also be provided to cover the entire portion excluding the terminal portions 41B and 42B.

[0140] 20, a sensor module 8 can be realized by a sensor 6B and a control device 7. In the sensor module 8, the sensor 6B is attached to an object to be measured, and the state of the object to be measured can be detected by the control device 7. Multiple sensors 6B may be attached to the object to be measured.

[0141] In the sensor module 8, the terminal portions 41B and 42B of the sensor 6B are connected to the control device 7 using, for example, a flexible substrate, lead wires, or the like.

[0142] The control device 7 can detect, for example, the coordinate of the position where the sensor 6B is pressed and the magnitude of the pressing force based on the information obtained via the terminals 41B and 42B. For example, the resistor 31B of the sensor 6B can be used to detect the X coordinate, and the resistor 32B can be used to detect the Y coordinate.

[0143] As shown in FIG. 21, the control device 7 can include, for example, an analog front-end unit 71 and a signal processing unit 72.

[0144] The analog front-end unit 71 includes, for example, an input signal selection switch, a bridge circuit, an amplifier, an analog / digital conversion circuit (A / D conversion circuit), etc. The analog front-end unit 71 may also include a temperature compensation circuit.

[0145] In the analog front-end unit 71, for example, all of the terminals 41B and 42B of the sensor 6B are connected to input signal selection switches, and a pair of electrodes is selected by the input signal selection switches. The pair of electrodes selected by the input signal selection switches is connected to a bridge circuit.

[0146] That is, one side of the bridge circuit is composed of a resistor section between a pair of electrodes selected by the input signal selection switch, and the other three sides are composed of fixed resistors. This makes it possible to obtain, as the output of the bridge circuit, a voltage (analog signal) corresponding to the resistance value of the resistor section between a pair of electrodes selected by the input signal selection switch. The input signal selection switch can be controlled by the signal processing unit 72.

[0147] The voltage output from the bridge circuit is amplified by an amplifier, converted into a digital signal by an A / D conversion circuit, and sent to the signal processing unit 72. If the analog front-end unit 71 is equipped with a temperature compensation circuit, the temperature-compensated digital signal is sent to the signal processing unit 72. By switching the input signal selection switch at high speed, digital signals corresponding to the resistance values of all of the terminal units 41B and 42B of the sensor 6B can be sent to the signal processing unit 72 in an extremely short time.

[0148] Based on the information sent from the analog front end unit 71, the signal processing unit 72 can detect the coordinates of the position where the sensor 6B is pressed and the magnitude of the pressing force.

[0149] Furthermore, if the resistance values of the plurality of resistor portions 31B and the resistance values of the plurality of resistor portions 32B change, it can be detected that the sensor 6B has been pressed at a plurality of positions.

[0150] In addition, when the magnitude of the pressing force is small, it may happen that only the resistor unit 31B or 32B that is closer to the pressed side is pressed, and the resistor unit farther from the pressed side is not pressed. In this case, only the resistance value between the pair of electrodes of the resistor unit closer to the pressed side changes continuously according to the magnitude of the pressing force, but even in this case, the signal processing unit 72 can detect the magnitude of the pressing force based on the magnitude of the change in the resistance value of the resistor unit closer to the pressed side.

[0151] That is, when the resistor 31B and / or the resistor 32B is pressed, the resistance value between the pair of electrodes of the pressed resistor (the resistor 31B and / or the resistor 32B) changes continuously depending on the magnitude of the pressing force. The signal processor 72 can detect the magnitude of the pressing force based on the magnitude of the change in the resistance value of the pressed resistor, regardless of whether one or both of the resistors 31B and 32B are pressed.

[0152] The signal processing unit 72 may include, for example, a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), a main memory, and the like.

[0153] In this case, the various functions of the signal processing unit 72 can be realized by reading a program recorded in a ROM or the like into a main memory and executing it by a CPU. However, part or all of the signal processing unit 72 may be realized solely by hardware. Furthermore, the signal processing unit 72 may be physically configured by multiple devices or the like.

[0154] Thus, in the fifth embodiment, a sensor 6B is used that has a resistor 30B that includes a plurality of resistor sections 31B arranged side by side with their longitudinal direction facing a first direction, and a plurality of resistor sections 32B arranged side by side with their longitudinal direction facing a second direction that intersects the first direction.

[0155] As a result, when resistor portions 31B and 32B are pressed, the pressed resistor portions 31B and 32B bend in response to the pressing force, and the resistance value between a pair of electrodes of the pressed resistor portions 31B and 32B changes continuously in response to the magnitude of the pressing force. That is, by using sensor 6B, three-dimensional information (the coordinates of the pressed position and the magnitude of the pressing force) can be obtained. That is, information on the entire object to be measured can be obtained, and the locations where the state of the object to be measured is changing can be grasped in detail, making it possible to accurately detect the state of the object to be measured.

[0156] In particular, when the resistor portions 31B and 32B are formed from a Cr mixed-phase film, the sensitivity of the resistance value to the pressing force (the amount of change in the resistance value of the resistor portions 31B and 32B with respect to the same pressing force) is significantly improved compared to when the resistor portions 31B and 32B are formed from Cu—Ni or Ni—Cr. When the resistor portions 31B and 32B are formed from a Cr mixed-phase film, the sensitivity of the resistance value to the pressing force is approximately 5 to 10 times higher compared to when the resistor portions 31B and 32B are formed from Cu—Ni or Ni—Cr. Therefore, by forming the resistor portions 31B and 32B from a Cr mixed-phase film, the detection accuracy of the coordinates of the pressed position can be improved, and the pressing force can be detected with high sensitivity.

[0157] Furthermore, the high sensitivity of the resistance value to the pressure makes it possible to realize control such that a predetermined operation is performed when a small pressure is detected, another operation is performed when a medium pressure is detected, and yet another operation is performed when a large pressure is detected. Alternatively, it is possible to realize control such that no operation is performed when a small or medium pressure is detected, and a predetermined operation is performed only when a large pressure is detected.

[0158] Furthermore, if the resistance value has high sensitivity to pressure, a signal with a high S / N ratio can be obtained. Therefore, accurate signal detection is possible even if the number of averaging operations in the A / D conversion circuit of the analog front end unit 71 is reduced. By reducing the number of averaging operations in the A / D conversion circuit, the time required for one A / D conversion can be shortened, making it possible to switch the input signal selection switch at even higher speeds. As a result, even fast movements input to the sensor module 8 can be detected.

[0159] Furthermore, when the resistor 30B is made of a Cr mixed phase film, the sensor 6B can be made smaller, which improves the degree of freedom in selecting the location where it is to be disposed.

[0160] <Modification 1 of the Fifth Embodiment> In the first modification of the fifth embodiment, an example in which the resistor portion of the sensor is formed in a zigzag pattern is shown. Note that in the first modification of the fifth embodiment, the description of the same components as those in the previously described embodiments may be omitted.

[0161] Fig. 22 is a plan view illustrating a sensor according to Modification 1 of the fifth embodiment, showing a plane corresponding to Fig. 18. Referring to Fig. 22, sensor 6C differs from sensor 6B (see Figs. 18 and 19) in that resistor 30B is replaced with resistor 30C.

[0162] The resistor 30C includes resistive portions 31C and 32C. The resistive portion 31C has a zigzag pattern formed between a pair of terminal portions 41B. The resistive portion 32C also has a zigzag pattern formed between a pair of terminal portions 42B. The material and thickness of the resistive portions 31C and 32C may be the same as, for example, the material and thickness of the resistive portions 31B and 32B.

[0163] In this way, by forming resistor portions 31C and 32C in a zigzag pattern, the resistance value between a pair of terminal portions 41B and the resistance value between a pair of terminal portions 42B can be increased compared to when they are formed in a linear pattern. As a result, the amount of change in the resistance value between a pair of terminal portions 41B and the amount of change in the resistance value between a pair of terminal portions 42B when pressed increases, which further improves the detection accuracy of the coordinates of the pressed position and enables force to be detected with even higher sensitivity.

[0164] Furthermore, since the resistance value between the pair of terminal portions 41B and the resistance value between the pair of terminal portions 42B can be increased, it is possible to reduce the power consumption of the sensor 6C.

[0165] Sixth Embodiment The sixth embodiment shows an application example in which a Cr mixed phase film is used as the material of the resistor 30 in the strain gauge according to the first embodiment. Note that in the sixth embodiment, the description of the same components as those in the already described embodiments may be omitted.

[0166] In the strain gauge 1 according to the first embodiment, when a Cr mixed-phase film is used as the material of the resistor 30, high sensitivity (500% or more compared to conventional devices) and miniaturization (1 / 10 or less compared to conventional devices) can be achieved. Hereinafter, the strain gauge 1 using the Cr mixed-phase film will be referred to as a strain gauge 3 for convenience.

[0167] For example, while the output of a conventional strain gauge was approximately 0.04 mV / 2 V, the strain gauge 3 can obtain an output of 0.3 mV / 2 V or more. Also, while the size of a conventional strain gauge (gauge length x gauge width) was approximately 3 mm x 3 mm, the size of the strain gauge 3 (gauge length x gauge width) can be reduced to approximately 0.3 mm x 0.3 mm.

[0168] Strain gauges are generally used by attaching them to a strain-generating body (metal, etc.). Conventional strain gauges have low sensitivity, so there were design restrictions on the material selection for the strain-generating body in order to ensure the sensor characteristics.

[0169] In contrast, the strain gauge 3 is more sensitive than conventional strain gauges, and therefore the design restrictions imposed when using conventional strain gauges can be significantly alleviated, allowing for greater freedom in selecting the material for the strain-generating body.

[0170] Furthermore, since the strain gauge 3 is smaller than conventional strain gauges, it can be installed in minute measurement locations where it was previously not possible to use a strain gauge.

[0171] Furthermore, since the strain gauge 3 is a flexible film-type gauge, it can be produced and supplied in a variety of sizes, not just small ones.

[0172] Furthermore, the strain gauge 3 is lightweight and can be attached to the location where measurement is desired, which gives it the advantage of being able to measure the desired location directly, compared to MEMS (Micro Electro Mechanical Systems) sensors, which require mounting on an electronic board for similar measurements.

[0173] In addition, the strain gauge 3 is very small and its mass can be ignored, so it is not affected by inertia and has excellent sensitivity, stability, and fatigue life.

[0174] Furthermore, the strain gauge 3 is capable of self-temperature compensation, in which case it can be used for measuring any object having a variety of thermal expansion coefficients, regardless of whether it is made of metal or plastic.

[0175] Furthermore, the strain gauge 3 is highly sensitive and can detect small displacements, so it can also be used for measuring objects with high rigidity.

[0176] Due to the above-mentioned characteristics, the strain gauge 3 can be used in a variety of applications. Specific application examples of the strain gauge 3 are shown below. <First application example> The air resistance of an automobile is invisible, unstable, and difficult to measure. This makes it difficult to grasp the downforce generated on the vehicle body and the air diagram of lift. In light of this, the first application example shows an example in which strain gauges 3 are used to detect the wind pressure and other factors that a moving automobile experiences.

[0177] Fig. 23 is a schematic diagram illustrating the air flow when an automobile 500 is traveling. When automobile 500 travels, air flows, for example, as shown by the arrows in Fig. 23. When the traveling speed of automobile 500 increases due to such air flows, lift is exerted on the vehicle body, causing the vehicle body to rise up, which may result in unstable traveling.

[0178] Therefore, automobile 500 has front spoiler 510, side spoiler 520, and rear spoiler (rear wing) 530. By having front spoiler 510, side spoiler 520, and rear spoiler 530, automobile 500 generates downforce in the direction of the arrow, reducing the lift acting on the vehicle body even when speeding up, thereby suppressing lifting of the vehicle body and enabling stable driving.

[0179] Fig. 24 is a perspective view showing an example in which a strain gauge 3 is attached to the spoiler of an automobile. An automobile 500A shown in Fig. 24 has a front spoiler 510A, a side spoiler 520A, and a rear spoiler (rear wing) 530A. A strain gauge 3 is attached to at least one of the front spoiler 510A, the side spoiler 520A, and the rear spoiler (rear wing) 530A.

[0180] The strain gauges 3 may be attached to or embedded in the surface of at least one of the front spoiler 510A, the side spoiler 520A, and the rear spoiler (rear wing) 530A, for example. Alternatively, an air intake may be provided in at least one of the front spoiler 510A, the side spoiler 520A, and the rear spoiler (rear wing) 530A, and the strain gauges 3 may be attached to or embedded in a location where the flow of the taken-in air concentrates.

[0181] In this way, by attaching the strain gauge 3 to the spoiler, it is possible to sense the wind pressure on the surface of the spoiler and detect the lift and downforce acting on the vehicle body.

[0182] Furthermore, by displaying the detected values on the Center Information Display (CID), E-Cockpit display, head-up display, etc., it becomes possible to visualize the downforce acting on the vehicle body and quantify the air diagram.

[0183] Spoilers are often made of resin to reduce weight, but the strain gauge 3 is made of a flexible base material and is lightweight and flexible, making it easy to attach and enabling highly sensitive detection of wind pressure.

[0184] Furthermore, if the spoiler is configured to be adjustable using a motor or the like, it is possible to adjust the spoiler based on the wind pressure detected by the strain gauge 3, thereby optimizing the lift and downforce acting on the vehicle body and achieving more stable driving.

[0185] As described above, the strain gauge 3 is highly sensitive and can easily detect wind pressure acting on the spoiler. Furthermore, by displaying the detection results on a display, it is possible to visualize airflow, such as downforce. Furthermore, by feeding back the detection results of the strain gauge 3 to the variable spoiler, it is possible to actively control the lift and downforce acting on the vehicle body, thereby achieving more stable driving. Furthermore, by converting the detection results into the degree of fuel economy impact caused by air resistance and displaying it on a display, it is possible to visualize fuel economy information. The strain gauge 3 may be used not only in engine-driven vehicles, but also in electric vehicles, hybrid vehicles, etc.

[0186] It is possible to use one or more strain gauges 3. Furthermore, instead of the strain gauge 3, it is also possible to use strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C that use a Cr mixed phase film as the resistor material. <Second application example> Automobile accelerator pedals are made of a highly rigid material (a material that is difficult to bend), and conventional sensors using strain gauges were unable to accurately sense the accelerator pedal force as an auxiliary sensor. In other words, conventional strain gauges have low sensitivity, so they could only be used to measure components made of a material that is easy to bend. Alternatively, when measuring components made of a highly rigid material (a material that is difficult to bend), the sensor was attached to the object to be measured via a strain generator made of a material with low rigidity (a material that is easy to bend). In view of this, the second application example shows an example of detecting accelerator pedal force using a strain gauge 3.

[0187] Fig. 25 is a perspective view showing an example in which a strain gauge 3 is attached to an accelerator pedal of an automobile. In Fig. 25, the strain gauge 3 is attached to the side of the accelerator pedal 540 of the automobile, but the strain gauge 3 may also be attached to the back surface or the like of the accelerator pedal 540. Alternatively, the strain gauge 3 may be embedded in the accelerator pedal 540.

[0188] Attaching strain gauge 3 to accelerator pedal 540 makes it possible to detect the depression force of accelerator pedal 540. By using a highly sensitive strain gauge 3, even if accelerator pedal 540 is made of a highly rigid material (a material that is difficult to bend), highly sensitive sensing becomes possible, making it possible to detect the depression force more accurately.

[0189] In this way, because the strain gauge 3 has high sensitivity, it can detect the depression force with high accuracy even when the accelerator pedal 540 is made of a highly rigid material (a material that is difficult to bend). This is expected to improve the speed controllability and fuel efficiency of the automobile.

[0190] It is possible to use one or more strain gauges 3. Furthermore, instead of the strain gauge 3, it is also possible to use strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C that use a Cr mixed phase film as the resistor material. <Third application example> The grip force applied to the steering wheel of a car can be detected, for example, by a dedicated sensor placed on the steering wheel. For example, the dedicated sensors can be placed in two symmetrical locations on the left and right that are easy to grip, and the grip force at the locations can be detected. The dedicated sensors can be placed, for example, between the core material and exterior of the steering wheel, but this placement can cause problems such as impairing the design of the steering wheel in some high-end cars. In consideration of this, the third application example is an example in which the grip force of the steering wheel is detected using a strain gauge 3.

[0191] Figure 26 is a perspective view showing a comparative example in which a dedicated sensor is attached to an automobile steering wheel. Figure 26(a) is a perspective view of the steering wheel, and also shows an enlarged view of the internal structure of the steering wheel. Figure 26(b) is a cross-sectional view taken along line EE in Figure 26(a).

[0192] 26 has a structure in which the outer periphery of a metal core 551 is covered with resin 552 such as urethane, dedicated sensors 3X for detecting grip force are arranged so as to be attached to the outer periphery of resin 552, and the outer periphery of dedicated sensors 3X is covered with exterior 553 made of leather or the like. Dedicated sensors 3X are arranged, for example, at two symmetrical positions on the left and right of annular steering wheel 550X that are easy to grip.

[0193] Dedicated sensor 3X has lower sensitivity than strain gauge 3, and therefore sensing is difficult if it is attached to the inside of metal core material 551, which is difficult to deform. For this reason, in steering wheel 550X, dedicated sensor 3X is attached to the outer periphery of resin 552, which is easy to deform.

[0194] On the other hand, because strain gauges 3 are highly sensitive, grip force sensing can be performed even when strain gauges 3 are attached inside core material 551, as in steering wheel 550 shown in the cross-sectional view of Fig. 27. That is, because strain gauges 3 are highly sensitive and can reliably detect even slight grip force, grip force sensing can be performed even when strain gauges 3 are attached inside core material 551. Note that Fig. 27 shows a cross section corresponding to Fig. 26.

[0195] Furthermore, as shown in Fig. 28, by arranging strain gauges 3 in the entire circumferential direction of the steering wheel 550, it becomes possible to detect grip force in a 360° direction. In this case, it becomes possible to detect grip force not only during normal driving as shown in Fig. 29(a) but also when gripping various positions on the steering wheel 550, such as when turning the steering wheel as shown in Fig. 29(b) and Fig. 29(c). However, the strain gauges 3 do not necessarily need to be arranged in the entire circumferential direction of the steering wheel 550, as long as they are arranged at least in a part of the steering wheel 550.

[0196] In this way, because strain gauge 3 is highly sensitive, it is possible to detect grip force even when attached inside highly rigid core material 551. Furthermore, by attaching strain gauge 3 inside core material 551, the design of steering wheel 550 is not affected, thereby improving the design of steering wheel 550.

[0197] Furthermore, by arranging highly sensitive strain gauges 3 in the all-around direction of the steering wheel 550, it becomes possible to detect grip force even when steering is performed while turning right or left, or while curving, etc.

[0198] It is possible to use one or more strain gauges 3. Furthermore, instead of the strain gauge 3, it is also possible to use strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C that use a Cr mixed phase film as the resistor material. <Fourth Application Example> Automobile door knobs (door handles) are used as a key insertion slot for locking the door and as a handle for opening and closing the door, but some luxury cars are considering removing door knobs because they have a negative impact on the image of the car body. Door knobs also have the disadvantage of being easily damaged due to their uneven shape. In view of this, the fourth application example shows an example of a door knob-less door that uses a strain gauge 3 to unlock the door.

[0199] FIG. 30 is a perspective view showing an example in which a strain gauge 3 is attached to a car door. FIG. 31 is a cross-sectional view showing an example in which a strain gauge 3 is attached to a car door. A door 560 shown in FIGS. 30 and 31 has an inner panel 561 and an outer panel 562, but does not have a door handle. A strain gauge 3 is attached to a predetermined position on the inside of the outer panel 562. Alternatively, the strain gauge 3 may be embedded in the outer panel 562.

[0200] By placing a strain gauge 3 at a predetermined position on the outer panel 562 side of the door 560, it is possible to detect that the predetermined position has been pressed, thereby unlocking the door. For example, the door may be structured to open and close using the power of a motor or the like, and when it is detected that the predetermined position where the strain gauge 3 is attached has been pressed, the door lock can be released using the power of the motor or the like to open the door.

[0201] By placing the strain gauge 3 at a predetermined position on the outer panel 562 side of the door 560, sensing can be performed inside the outer panel 562, without compromising the design of the vehicle body. In addition, the strain gauge 3 is highly sensitive, so it can reliably detect door unlocking.

[0202] For example, strain gauges 3 may be arranged in multiple locations on the outer panel 562, and the door may be unlocked and opened / closed when the strain gauges 3 arranged in multiple locations are pressed in a predetermined specific order. This can prevent false detection and allows only specific people to unlock the door and open / close the door, making it possible to use this for door lock authentication.

[0203] Alternatively, the sensor 6B (see FIGS. 18 and 19) may be placed at a predetermined position on the outer panel 562 side, and the sensor 6B may detect that a predetermined specific input pattern has been traced with a finger or the like. In this case, false detection can also be prevented, and only specific persons can unlock the door and open and close the door, making it possible to use this for door lock authentication.

[0204] In this way, the use of strain gauges 3 not only eliminates the need for door handles to open and close doors, but also increases the degree of freedom in car body design, making it possible to design beautiful car bodies like those sought by some luxury cars. Furthermore, it will be possible to propose a new opening and closing system that is less likely to scratch the doors when they are opened and closed.

[0205] It is possible to use one or more strain gauges 3. Furthermore, instead of the strain gauge 3, it is also possible to use strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C that use a Cr mixed phase film as the resistor material. <5th application example> Electronic Stability Control (ESC) is a preventive safety (active safety) system that detects unstable vehicle posture, such as oversteer or understeer, and controls the vehicle's basic performance of turning. ESC systems typically use tilt sensors. Specifically, they use "pendulum-type" or "float-type" tilt sensors that detect the deviation between a weight suspended in the direction of gravity or the liquid level and an inclined object. MEMS acceleration sensors and gyros (angular velocity sensors) have also been used. However, tilt sensors have accuracy issues, and acceleration sensors and gyros (angular velocity sensors) are expensive and cost-intensive. In consideration of these issues, the fifth application example shows an example of detecting vehicle posture using strain gauges 3.

[0206] Fig. 32 is a perspective view showing an example of a six-axis force sensor having strain gauges 3. A six-axis force sensor 570 shown in Fig. 32 has a strain element 571 including an outer frame 572 and four beams 573, a weight 574, and a plurality of strain gauges 3.

[0207] Each of the four beams 573 is a rectangular prism, and is arranged to form a cross on the inner wall side of the outer frame 572. Two strain gauges 3 are arranged side by side on each surface of each beam 573, for a total of 32 strain gauges 3. However, the shapes of the outer frame 572 and beams 573 of the strain element 571 and the number of strain gauges 3 are merely examples, and are not limited to these.

[0208] In six-axis force sensor 570, the intersection of four beams 573 arranged to form a cross serves as a sensing part, and weight 574 is fixed to the sensing part. As a result, six-axis force sensor 570 can detect translational forces and couples in three axial directions with a single sensor.

[0209] The six-axis force sensor 570 can be placed, for example, near the center of gravity G of the automobile 500B shown in Fig. 33. This causes the weight 574 of the six-axis force sensor 570 to tilt in response to the attitude of the automobile 500B, making it possible to detect the up-and-down movement, left-and-right movement, forward movement, yawing movement, pitching movement, and rolling movement of the automobile 500B, thereby enabling control of the attitude of the vehicle body.

[0210] In this way, by using the 6-axis force sensor 570 having the strain gauges 3 as a sensor for controlling the vehicle body posture, a simple ESC can be constructed, and an inexpensive and safe ESC system can be realized. Furthermore, by using the highly sensitive strain gauges 3, even slight posture deviations such as oversteer and understeer can be detected, and an inexpensive and safe ESC system can be easily realized.

[0211] Furthermore, the attitude control of the fifth application example may be used in combination with the control of the variable spoiler of the first application example. For example, by controlling the variable spoiler so as to stabilize the attitude of the vehicle body detected by the six-axis force sensor 570, it is possible to prevent an accident in which the automobile 500B is hit by a strong wind and rolls over.

[0212] It is possible to use one or more strain gauges 3. Furthermore, instead of the strain gauge 3, it is also possible to use strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C that use a Cr mixed phase film as the resistor material. <Sixth Application Example> In the sixth application example, the strain gauge 3 is used to detect the operating state of a wiper.

[0213] Fig. 34 is a schematic diagram showing an example in which a strain gauge 3 is attached to a windshield wiper of an automobile. In Fig. 34, 380 denotes two wipers, and a strain gauge 3 is attached to the surface of each wiper 580. Alternatively, the strain gauge 3 may be embedded in the wiper 580.

[0214] By attaching the strain gauge 3 to the wiper 580, it is possible to detect the sliding state of the wiper 580 and the state of wiping unevenness (wiping unevenness).

[0215] It is also possible to vary the operating speed of the wiper 580 based on the detection results of the strain gauge 3. Alternatively, the wiper 580 may be configured so that the angle of the rubber portion is variable, and the angle of the rubber portion may be varied based on the detection results of the strain gauge 3 to improve the sliding state or uneven wiping. It is also possible to detect wear on the rubber portion of the wiper 580 based on the detection results of the strain gauge 3.

[0216] It is possible to use one or more strain gauges 3. Furthermore, instead of the strain gauge 3, it is also possible to use strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C that use a Cr mixed phase film as the resistor material. <7th Application Example> In the seventh application example, an example in which the strain gauge 3 is used to activate an airbag is shown.

[0217] 35 is a schematic diagram showing an example in which a strain gauge 3 is attached to the bumper of an automobile, illustrating the automobile colliding with a wall. In FIG. 35, a strain gauge 3 is attached to bumper 590 of automobile 500C. Alternatively, the strain gauge 3 may be embedded in bumper 590. In FIG. 35, the left side of bumper 590 of automobile 500C collides with wall 700.

[0218] By attaching a strain gauge 3 to the bumper 590, it is possible to detect the impact that the automobile 500C receives and activate the airbag. Alternatively, it is also possible to attach a strain gauge 3 to the airbag and detect whether the pressure when the airbag is activated is appropriate.

[0219] It is possible to use one or more strain gauges 3. Furthermore, instead of the strain gauge 3, it is also possible to use strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C that use a Cr mixed phase film as the resistor material. <8th Application Example> In the eighth application example, a malfunction of an engine or a supercharger is detected using the strain gauge 3.

[0220] Fig. 36 is a schematic diagram showing an example in which strain gauges 3 are arranged near an automobile engine and a supercharger. In Fig. 36, 610 is a supercharger, 620 is an exhaust turbine, 630 is an intake valve, and 640 is an exhaust valve, and strain gauges 3 are arranged near the supercharger 610.

[0221] By placing the strain gauge 3 near the engine or a turbocharger such as a turbocharger or supercharger, it is possible to detect malfunctions of the engine or turbocharger, for example, by detecting changes in pressure. Furthermore, based on the detection results of the strain gauge 3, it is also possible to reduce the engine speed or stop the engine.

[0222] When the temperature inside the engine becomes high, it is preferable to use a highly heat-resistant material such as ceramic (for example, alumina, zirconia, or sapphire) as the base material 10 of the strain gauge 3, rather than resin.

[0223] It is possible to use one or more strain gauges 3. Furthermore, instead of the strain gauge 3, it is also possible to use strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C that use a Cr mixed phase film as the resistor material.

[0224] The above describes in detail preferred embodiments, but 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]

[0225] 1, 1A, 2, 2A, 2B, 3 strain gauge, 5 sensor module, 6A, 6B, 6C sensor, 7 control device, 10 substrate, 10a upper surface, 20 functional layer, 30, 30B, 30C resistor, 31B, 31C, 32B, 32C resistor section, 41, 41B, 42B terminal section, 40A, 40B, 40C electrode, 42, 43, 44, 44A, 45, 45A metal layer, 50 insulating layer, 60 cover layer, 70 individual sensor, 71 analog front end section, 72 signal processing section, 110 strain element, 120 adhesive layer, 500, 500A, 500B, 500C automobile, 510, 510A front spoiler, 520, 520A Side spoiler, 530, 530A Rear spoiler, 540 Accelerator pedal, 550 Steering wheel, 551 Core material, 552 Resin, 553 Exterior, 560 Door, 561 Inner panel, 562 Outer panel, 570 Six-axis force sensor, 571 Strain body, 572 Outer frame, 573 Beam, 574 Weight, 580 Wiper, 590 Bumper, 610 Supercharger, 620 Exhaust turbine, 630 Intake valve, 640 Exhaust valve, Wall 700

Claims

1. An accelerator pedal of a motor vehicle, a sensor for detecting the depression force of the accelerator pedal; The sensor a flexible resin substrate; a functional layer formed of a metal, an alloy, or a metal compound directly on one surface of the substrate; Cr, CrN, and Cr are directly applied to one surface of the functional layer. ２ a resistor formed from a film containing N and containing α-Cr as a main component; the functional layer has a function of promoting crystal growth of the α-Cr and forming a film containing the α-Cr as a main component; The resistor has a thickness of 0.05 μm or more and 2 μm or less, The thickness of the functional layer is 1 nm or more and 100 nm or less, An accelerator pedal that detects the depression force of the accelerator pedal as a change in the resistance value of the resistor.

2. The sensor 2. The accelerator pedal according to claim 1, wherein the accelerator pedal is provided on a side surface of the accelerator pedal.

3. The accelerator pedal 3. The accelerator pedal according to claim 1, wherein the accelerator pedal is made of a material having high rigidity.

4. The resistor is a plurality of first resistors arranged side by side on one side of the substrate with their longitudinal directions directed in a first direction; 4. The accelerator pedal according to claim 1, further comprising: a plurality of second resistors arranged side by side on the other side of the base member, the longitudinal direction of the second resistors being oriented in a second direction intersecting the first direction.

5. A steering wheel for a motor vehicle, a sensor for detecting the grip force of the steering wheel; The sensor a flexible resin substrate; a functional layer formed of a metal, an alloy, or a metal compound directly on one surface of the substrate; Cr, CrN, and Cr are directly applied to one surface of the functional layer. ２ a resistor formed from a film containing N and containing α-Cr as a main component; the functional layer has a function of promoting crystal growth of the α-Cr and forming a film containing the α-Cr as a main component; The resistor has a thickness of 0.05 μm or more and 2 μm or less, The thickness of the functional layer is 1 nm or more and 100 nm or less, A steering wheel that detects the grip force of the steering wheel as a change in the resistance value of the resistor.

6. A core material formed of a highly rigid material; a resin that coats the outer periphery of the core material, The sensor The steering wheel according to claim 5, wherein the core member is provided inside the core member.

7. The sensor The steering wheel according to claim 6, wherein the core member is provided in an entire circumferential direction inside the core member.

8. The resistor is a plurality of first resistors arranged side by side on one side of the substrate with their longitudinal directions directed in a first direction; The steering according to any one of claims 5 to 7, further comprising: a plurality of second resistors arranged side by side on the other side of the base member, the longitudinal direction of the second resistors being oriented in a second direction intersecting the first direction.

9. A door of a motor vehicle, The inner panel and an outer panel; a sensor provided at a predetermined position inside the outer panel to detect a pressing force at the predetermined position; The sensor a flexible resin substrate; a functional layer formed of a metal, an alloy, or a metal compound directly on one surface of the substrate; Cr, CrN, and Cr are directly applied to one surface of the functional layer. ２ a resistor formed from a film containing N and containing α-Cr as a main component; the functional layer has a function of promoting crystal growth of the α-Cr and forming a film containing the α-Cr as a main component; The resistor has a thickness of 0.05 μm or more and 2 μm or less, the thickness of the functional layer is 1 nm or more and 100 nm or less; The door detects the pressing force of the outer panel as a change in the resistance value of the resistor.

10. 10. The door according to claim 9, wherein a plurality of the sensors are provided at a plurality of locations on the inside of the outer panel.

11. The resistor is a plurality of first resistors arranged side by side on one side of the substrate with their longitudinal directions directed in a first direction; The door according to claim 9 or 10, further comprising: a plurality of second resistors arranged side by side on the other side of the base member, the longitudinal direction of the second resistors being oriented in a second direction intersecting the first direction.

12. A door according to any one of claims 9 to 11; and an opening / closing mechanism that opens and closes the door based on the detection of the pressing force.

13. A door according to any one of claims 9 to 11; and an opening / closing mechanism that unlocks the door or opens / closes the door when the plurality of sensors are pressed in a predetermined specific order.

14. A door according to any one of claims 9 to 11; an opening / closing mechanism that unlocks a door or opens or closes a door when the sensor is traced with a predetermined specific input pattern; A door opening and closing system comprising:

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