Accelerator pedal, steering wheel, doors, door opening / 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, a steering wheel, a door, and a door opening / closing system of an automobile equipped with sensors.

Background Art

[0002] A strain gauge that is attached to a measurement object to detect the strain of the measurement object is known. The strain gauge includes a resistor for detecting strain, and as the material of the resistor, for example, a material containing Cr (chromium) or Ni (nickel) is used. Further, the resistor is formed on a base material made of, for example, an insulating resin (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when using a strain gauge for a measurement object having high rigidity, high sensitivity is required. However, since the sensitivity of conventional strain gauges was not sufficient, it was difficult to use them for measurement objects having high rigidity.

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

Means for Solving the Problems

[0006] This accelerator pedal is an accelerator pedal for an automobile, and is equipped with a sensor that detects the force with which the accelerator pedal is pressed. The sensor comprises a flexible resin substrate, a functional layer formed directly on one surface of the substrate from a metal, alloy, or metal compound, and a resistor mainly composed of α-Cr, formed directly on one surface of the functional layer from a film containing Cr, CrN, and Cr2N. The functional layer has the function of promoting the crystal growth of α-Cr and forming a film mainly composed of α-Cr. The thickness of the resistor is 0.05 μm to 2 μm, and the thickness of the functional layer is 1 nm to 100 nm. The force with which the accelerator pedal is pressed is detected as a change in the resistance value of the resistor. [Effects of the Invention]

[0007] According to the disclosed technology, it is possible to provide an accelerator pedal, etc., equipped with a highly sensitive sensor. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view illustrating a strain gauge according to the first embodiment. [Figure 2] This is a cross-sectional view illustrating a strain gauge according to the first embodiment. [Figure 3] This figure illustrates the manufacturing process of a strain gauge according to the first embodiment. [Figure 4] This is a cross-sectional view illustrating a strain gauge according to a modified example 1 of the first embodiment. [Figure 5] This is a plan view illustrating a strain gauge according to a second embodiment. [Figure 6] This is a cross-sectional view illustrating a strain gauge according to a second embodiment. [Figure 7] This is a diagram (part 1) illustrating the manufacturing process of a strain gauge according to the second embodiment. [Figure 8] This is a diagram (part 2) illustrating the manufacturing process of a strain gauge according to the second embodiment. [Figure 9]Cross-sectional view illustrating a strain gauge according to Modification 1 of the Second Embodiment. [Figure 10] Cross-sectional view illustrating a strain gauge according to Modification 2 of the Second Embodiment. [Figure 11] Cross-sectional view illustrating a sensor module according to the Third Embodiment. [Figure 12] Diagram showing the results of fluorescence X-ray analysis of the functional layer. [Figure 13] Diagram showing the results of X-ray diffraction of the resistor. [Figure 14] Diagram showing the relationship between the expansion coefficient of the base material and the internal stress of the resistor. [Figure 15] Diagram showing the relationship between the surface unevenness of the base material and the number of pinholes in the resistor. [Figure 16] Plan view illustrating a sensor according to the Fourth Embodiment. [Figure 17] Cross-sectional view illustrating a sensor according to the Fourth Embodiment. [Figure 18] Plan view illustrating a sensor according to the Fifth Embodiment. [Figure 19] Cross-sectional view illustrating a sensor according to the Fifth Embodiment. [Figure 20] Block diagram illustrating a sensor module according to the Fifth Embodiment. [Figure 21] Block diagram illustrating a control device of a sensor module according to the Fifth Embodiment. [Figure 22] Plan view illustrating a sensor according to Modification 1 of the Fifth Embodiment. [Figure 23] Schematic diagram illustrating the air flow when an automobile is running. [Figure 24] Perspective view showing an example in which a strain gauge 3 is attached to a spoiler of an automobile. [Figure 25] Perspective view showing an example in which a strain gauge 3 is attached to an accelerator pedal of an automobile. [Figure 26] Perspective view showing a comparative example in which a dedicated sensor is attached to a steering of an automobile. [Figure 27] It is a cross-sectional view showing an example in which a strain gauge 3 is attached to the steering of an automobile. [Figure 28] It is a plan view showing an example in which a strain gauge 3 is attached to the steering of an automobile. [Figure 29] It is a schematic diagram for explaining the detection of the grip force of the steering of an automobile. [Figure 30] It is a perspective view showing an example in which a strain gauge 3 is attached to the door of an automobile. [Figure 31] It is a cross-sectional view showing an example in which a strain gauge 3 is attached to the door of an automobile. [Figure 32] It is a perspective view showing an example of a six-axis force sensor having a strain gauge 3. [Figure 33] It is a perspective view for explaining the position where a six-axis force sensor is arranged. [Figure 34] It is a schematic diagram showing an example in which a strain gauge 3 is attached to the wiper of an automobile. [Figure 35] It is a schematic diagram showing an example in which a strain gauge 3 is attached to the bumper of an automobile. [Figure 36] It is a schematic diagram showing an example in which a strain gauge 3 is arranged near the engine and supercharger of an automobile.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same reference numerals are given to the same constituent parts, and redundant explanations may be omitted.

[0010] 〈First Embodiment〉 Figure 1 is a plan view illustrating a strain gauge according to the first embodiment. Figure 2 is a cross-sectional view illustrating a strain gauge according to the first embodiment, showing a cross-section along line AA in Figure 1. Referring to Figures 1 and 2, the strain gauge 1 includes a base material 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 Figure 1, for convenience in illustrating the resistor 30, only the outer edge of the cover layer 60 is shown with a dashed line.

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

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

[0013] The base material 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, or polyolefin resin. The term "film" refers to a flexible material with a thickness of approximately 500 μm or less.

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

[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 Figure 1. The thickness of the functional layer 20 can be, for example, about 1 nm to 100 nm.

[0016] In this application, the functional layer refers to a layer that has the function of promoting crystal growth of the resistor 30, which is at least the upper layer. Preferably, the functional layer 20 further has the function of preventing oxidation of the resistor 30 by oxygen and moisture contained in the substrate 10, and the function of improving the adhesion between the substrate 10 and the resistor 30. The functional layer 20 may further have other functions.

[0017] Since the insulating resin film that makes up the base material 10 contains oxygen and moisture, and especially when the resistor 30 contains Cr (chromium), the Cr forms an oxidation film, it is effective for the functional layer 20 to have a function to prevent oxidation of the resistor 30.

[0018] The material of the functional layer 20 is not particularly limited as long as it is a material that has the function of promoting crystal growth of the upper layer resistor 30, and can be appropriately selected according to the purpose. Examples include 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), and Bi (bismuth). Examples 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 these metals, or a compound of any of these metals.

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

[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 sensitive part that changes its resistance value when subjected to strain. For convenience, in Figure 1, the resistor 30 is shown with a textured surface.

[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 multiphase 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, a Cr multiphase film is a film in which Cr, CrN, Cr2N, etc., are mixed. The Cr multiphase film may contain unavoidable impurities such as chromium oxide. In addition, some of the material constituting the functional layer 20 may be diffused into the Cr multiphase film. In this case, the material constituting the functional layer 20 and nitrogen may form a compound. For example, if the functional layer 20 is made of Ti, the Cr multiphase film may contain Ti or TiN (titanium nitride).

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

[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, gauge factor temperature coefficient TCS, and resistance temperature coefficient TCR).

[0025] For example, if the resistor 30 is a Cr multiphase film, a resistor 30 mainly composed of α-Cr (alpha-chromium) can be formed by providing a 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 substance in question accounts for 50% or more by mass of the total substances constituting the resistor. When the resistor 30 is a Cr multiphase film, it is preferable that the resistor 30 contains 80% or more by weight of α-Cr from the viewpoint of improving 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 the diffusion of the metal (e.g., Ti) constituting the functional layer 20 into the Cr multiphase film. Specifically, the gauge factor of the strain gauge 1 can be set to 10 or higher, and the gauge factor temperature coefficient TCS and resistance temperature coefficient TCR can be set within the range of -1000 ppm / °C to +1000 ppm / °C.

[0028] Furthermore, from the viewpoint of reducing the warping of the base material 10 by keeping the internal stress of the resistor 30 near zero, it is preferable that the thermal expansion coefficient of the base material 10 be 7 ppm / K to 20 ppm / K. The thermal expansion coefficient of the base material 10 can be adjusted, for example, by selecting the material of the base material 10, selecting the material of the filler contained in the base material 10 and adjusting its content.

[0029] Incidentally, when a resistor 30 is formed on a substrate 10, pinholes may occur in the resistor 30. If the number of pinholes in the resistor 30 exceeds a predetermined value, the gauge characteristics may deteriorate or the resistor may cease to function as a strain gauge. The inventors have discovered that one of the causes of pinholes occurring in the resistor 30 is filler protruding from the upper surface 10a of the substrate 10.

[0030] In other words, when the substrate 10 contains filler, a portion of the filler protrudes from the upper surface 10a of the substrate 10, increasing the surface irregularities of the upper surface 10a of the substrate 10. As a result, the number of pinholes formed in the resistor 30 on the upper surface 10a of the substrate 10 increases, leading to factors such as deterioration of gauge characteristics.

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

[0032] In other words, when the thickness of the resistor 30 is 0.05 μm or more, from the viewpoint of reducing the number of pinholes formed in the resistor 30 on the upper surface 10a of the substrate 10 and maintaining the gauge characteristics, it is preferable that the surface irregularities of the upper surface 10a of the substrate 10 be 15 nm or less. If the surface irregularities are 15 nm or less, the presence of filler in the substrate 10 will not lead to a deterioration of the gauge characteristics. Note that the surface irregularities of the upper surface 10a of the substrate 10 may be 0 nm.

[0033] Surface irregularities on 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, methods such as irradiating the upper surface 10a of the substrate 10 with laser light approximately perpendicular to it to remove the protrusions, moving a water cutter or the like parallel to the upper surface 10a of the substrate 10 to remove the protrusions, polishing the upper surface 10a of the substrate 10 using a grinding wheel, or heating and pressing the substrate 10 (heat press) may be used.

[0034] Surface roughness refers to the arithmetic mean roughness, generally denoted as Ra. Surface roughness can be measured, for example, by three-dimensional optical interferometry.

[0035] The terminal portion 41 extends from both ends of the resistor 30 and, in a plan view, is wider than the resistor 30 and is formed in a substantially rectangular shape. The terminal portion 41 is a pair of electrodes for outputting the change in the resistance value of the resistor 30 caused by strain to the outside, and for example, lead wires for external connection are joined to it. The resistor 30 extends from one terminal portion 41 in a zigzag pattern and is connected to the other terminal portion 41. The upper surface of the terminal portion 41 may be covered with a metal that has better solderability than the terminal portion 41. Although the resistor 30 and the terminal portion 41 are given different reference numerals for convenience, both can be formed integrally 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 base material 10 so as to cover the resistor 30 and expose the terminal portion 41. By providing the cover layer 60, mechanical damage to the resistor 30 can be prevented. In addition, by providing the cover layer 60, the resistor 30 can be protected from moisture and other elements. The cover layer 60 may be provided so as to cover the entire portion excluding the terminal portion 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, polyolefin resin). The cover layer 60 may contain fillers or pigments. There are no particular restrictions on the thickness of the cover layer 60, and it can be appropriately selected depending on the purpose, but for example, it can be about 2 μm to 30 μm.

[0038] Figure 3 is a diagram illustrating the manufacturing process of a strain gauge according to the first embodiment, and shows a cross-section corresponding to Figure 2. In order to manufacture the strain gauge 1, first, in the process shown in Figure 3(a), a base material 10 is prepared, and a functional layer 20 is formed on the upper surface 10a of the base material 10. The materials and thicknesses of the base material 10 and the functional layer 20 are as described above.

[0039] The functional layer 20 can be deposited using a conventional sputtering method, for example, by targeting a raw material capable of forming the functional layer 20 and introducing Ar (argon) gas into a chamber. By using the conventional sputtering method, the functional layer 20 is deposited while etching the upper surface 10a of the substrate 10 with Ar, thus minimizing the amount of functional layer 20 deposited and achieving improved adhesion.

[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, the upper surface 10a of the substrate 10 may be activated by plasma treatment using Ar or the like before forming the functional layer 20 to improve adhesion, and then the functional layer 20 may be formed in a vacuum by magnetron sputtering.

[0041] Next, in the process shown in Figure 3(b), the resistor 30 and 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 into the planar shape shown in Figure 1 by photolithography. The material and thickness of the resistor 30 and terminal portion 41 are as described above. The resistor 30 and the terminal portion 41 can be formed integrally from the same material. The resistor 30 and the terminal portion 41 can be deposited, for example, by a magnetron sputtering method targeting a raw material capable of forming the resistor 30 and the terminal portion 41. The resistor 30 and the terminal portion 41 may also be deposited using reactive sputtering, evaporation, arc ion plating, pulsed laser deposition, etc., instead of magnetron sputtering.

[0042] There are no particular restrictions on the combination of materials for the functional layer 20 and the resistor 30 and terminal portion 41, and they can be appropriately selected according to the purpose. For example, it is possible to use Ti as the functional layer 20 and deposit a Cr multiphase film mainly composed of α-Cr (alpha-chromium) as the resistor 30 and terminal portion 41.

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

[0044] In these methods, the functional layer 20 made of Ti initiates the growth surface of the Cr multiphase film, enabling the formation of a Cr multiphase film mainly composed of α-Cr, which has a stable crystalline structure. Furthermore, the diffusion of Ti constituting the functional layer 20 into the Cr multiphase film improves the gauge characteristics. For example, the gauge factor of strain gauge 1 can be set to 10 or higher, and the gauge factor temperature coefficient TCS and resistance temperature coefficient TCR can be set within the range of -1000 ppm / °C to +1000 ppm / °C.

[0045] Furthermore, when the resistor 30 is a Cr multiphase 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 by oxygen and moisture contained in the substrate 10, and improving the adhesion between the substrate 10 and the resistor 30. The same applies when Ta, Si, Al, or Fe is used instead of Ti as the functional layer 20.

[0046] Next, in the process shown in Figure 3(c), a cover layer 60 is formed on the upper surface 10a of the base material 10, covering the resistor 30 and exposing the terminal portion 41. The material and thickness of the cover layer 60 are as described above. The cover layer 60 can be made, for example, by laminating a semi-cured thermosetting insulating resin film onto the upper surface 10a of the base material 10 so as to cover the resistor 30 and expose the terminal portion 41, and then heating and curing it. Alternatively, the cover layer 60 may be made by applying a liquid or paste-like thermosetting insulating resin to the upper surface 10a of the base material 10 so as to cover the resistor 30 and expose the terminal portion 41, and then heating and curing it. Through the above process, the strain gauge 1 is completed.

[0047] Thus, by providing a functional layer 20 beneath the resistor 30, it becomes possible to promote crystal growth in the resistor 30, and a resistor 30 consisting of a stable crystalline phase can be fabricated. As a result, the stability of the gauge characteristics in the strain gauge 1 can be improved. Furthermore, the diffusion of the material constituting the functional layer 20 into the resistor 30 can improve the gauge characteristics in the strain gauge 1.

[0048] <Modification 1 of the first embodiment> Modification 1 of the first embodiment shows an example of a strain gauge in which an insulating layer is provided below the cover layer. In Modification 1 of the first embodiment, descriptions of components that are the same as those described in the previously described embodiment may be omitted.

[0049] Figure 4 is a cross-sectional view illustrating a strain gauge according to modification 1 of the first embodiment, and shows the cross-section corresponding to Figure 2. Referring to Figure 4, strain gauge 1A differs from strain gauge 1 (see Figures 1, 2, etc.) in that an insulating layer 50 is provided below the cover layer 60. The cover layer 60 may be provided to cover the entire portion excluding the terminal portion 41.

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

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

[0052] There are no particular restrictions on the method for forming the insulating layer 50, and it can be appropriately selected depending on the purpose. For example, vacuum processes such as sputtering or chemical vapor deposition (CVD), or solution processes such as spin coating or sol-gel coating can be used.

[0053] In this way, by providing an insulating layer 50 below the cover layer 60, the insulating properties and environmental sealing properties can be improved compared to the case where the cover layer 60 is used alone. Therefore, the insulating layer 50 can be provided as appropriate according to the required specifications for insulating properties and environmental sealing properties.

[0054] <Second Embodiment> The second embodiment shows an example of a strain gauge in which the electrodes have a stacked structure. In the second embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

[0055] Figure 5 is a plan view illustrating a strain gauge according to the second embodiment. Figure 6 is a cross-sectional view illustrating a strain gauge according to the second embodiment, showing a cross-section along line BB in Figure 5. Referring to Figures 5 and 6, the strain gauge 2 includes an electrode 40A made up of multiple layers. The cover layer 60 may be provided to cover the entire portion excluding the electrode 40A.

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

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

[0058] The material of the metal layer 43 is preferably Cu, Cu alloy, Ni, or Ni alloy. The thickness of the metal layer 43 is determined considering the solderability to the electrode 40A, but is preferably 1 μm or more, more preferably 3 μm or more. Solder erosion is improved by using Cu, Cu alloy, Ni, or 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 further improved by using Cu, Cu alloy, Ni, or Ni alloy as the material of the metal layer 43 and making the thickness of the metal layer 43 3 μm or more. However, for ease of electroplating, the thickness of the metal layer 43 is preferably 30 μm or less.

[0059] Here, solder erosion refers to the process where the material constituting the electrode 40A melts into the solder to which it is joined, causing the electrode 40A to become thinner or disappear altogether. Since solder erosion can reduce the adhesive strength and tensile strength of the lead wires and other components joined to the electrode 40A, it is preferable to prevent solder erosion from occurring.

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

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

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

[0063] The metal layer 300 can be formed, for example, by a magnetron sputtering method targeting a raw material capable of forming the metal layer 300. Alternatively, the metal layer 300 may be formed using reactive sputtering, evaporation, arc ion plating, pulsed laser deposition, or other methods instead of magnetron sputtering.

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

[0065] Next, in the step shown in Figure 7(c), a photosensitive resist 800 is formed on the entire upper surface of the seed layer 420, and exposure and development are performed to form an opening 800x that exposes the area in which the electrode 40A will be formed. For example, a dry film resist can be used as the resist 800.

[0066] Next, in the process shown in Figure 7(d), for example, a metal layer 43 is formed on the seed layer 420 exposed within the opening 800x by an electroplating method using the seed layer 420 as the power supply path, and then a metal layer 44 is formed on the metal layer 43. The electroplating method is preferable because it has a high cycle time and can form a low-stress electroplated layer as the metal layer 43. By making the thick electroplated layer low-stress, warping of the strain gauge 2 can be prevented. The metal layer 44 may also be formed on the metal layer 43 by an electroless plating method.

[0067] Furthermore, since the sides of the metal layer 43 are covered with the resist 800 when forming the metal layer 44, the metal layer 44 is formed only on the top surface of the metal layer 43 and not on the sides.

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

[0069] Next, in the process shown in Figure 8(b), a photosensitive resist 810 is formed on the entire upper surface of the seed layer 420, exposed and developed to pattern it into a planar shape similar to the resistor 30 and terminal portion 41 in Figure 5. For the resist 810, for example, a dry film resist can be used.

[0070] Next, in the process shown in Figure 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 planar functional layer 20, resistor 30, and terminal portion 41 shown in Figure 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] Next, in the process shown in Figure 8(d), metal layers 43 and 44 are used as etching masks to remove the unwanted seed layer 420 exposed from metal layers 43 and 44, thereby forming metal layer 42. For example, the unwanted seed layer 420 can be removed by wet etching using an etching solution that etches the seed layer 420 but not the functional layer 20 and the resistor 30.

[0072] After the process shown in Figure 8(d), the strain gauge 2 is completed by forming a cover layer 60 on the upper surface 10a of the substrate 10, covering the resistor 30 and exposing the electrode 40A, in the same manner as the process shown in Figure 3(c).

[0073] Thus, as the electrode 40A, a metal layer 43 made of a thick film (1 μm or more) of Cu, Cu alloy, Ni, or Ni alloy is formed on the terminal portion 41, and further, a metal layer 44 made of a material with better solder wettability than the metal layer 43 (Au or Pt) is formed on the outermost layer. Therefore, solder corrosion can be prevented and solder wettability can be improved.

[0074] <Modification 1 of the second embodiment> Modification 1 of the second embodiment shows an example of an electrode with a different layer structure from that of the second embodiment. In Modification 1 of the second embodiment, descriptions of components that are the same as those described in the previously described embodiment may be omitted.

[0075] Figure 9 is a cross-sectional view illustrating a strain gauge according to modification 1 of the second embodiment, and shows the cross-section corresponding to Figure 6. Referring to Figure 9, strain gauge 2A differs from strain gauge 2 (see Figure 6, etc.) in that electrode 40A is replaced with electrode 40B. Also, the cover layer 60 is provided to cover almost the entire portion excluding electrode 40B, which is another difference from strain gauge 2 (see Figure 6, etc.).

[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, a metal layer 42 formed on the upper surface of terminal portions 41, a metal layer 43 formed on the upper surface of metal layer 42, a metal layer 45 formed on the upper surface of metal layer 43, and a 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] There are no particular restrictions on the material of the metal layer 45, and it can be appropriately selected depending on the purpose, but for example, Ni can be used. NiP (nickel phosphorus) or Pd can be used instead of Ni. Alternatively, the metal layer 45 can be Ni / Pd (a metal layer in which a Ni layer and a Pd layer are stacked in that order). There are no particular restrictions on the thickness of the metal layer 45, and it can be appropriately selected depending on the purpose, but for example, it can be about 1 μm to 2 μm.

[0078] The metal layer 45 can be formed on the metal layer 43 by, for example, an electroplating method using the seed layer 420 as a power supply path, in the process shown in Figure 7(d).

[0079] Thus, the number of electrode layers is not particularly limited, and the number of layers can be increased as needed. In this case as well, a metal layer 43 made of a thick film (1 μm or more) of Cu, Cu alloy, Ni, or Ni alloy is formed on the terminal portion 41, and a metal layer 44 made of a material with better solder wettability than the metal layer 43 (Au or Pt) is formed on the outermost layer. Therefore, as in the second embodiment, solder corrosion 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 with a different layer structure from that of the second embodiment. In Modification 2 of the second embodiment, descriptions of components that are the same as those described in the previously described embodiment may be omitted.

[0081] Figure 10 is a cross-sectional view illustrating a strain gauge according to a modified example 2 of the second embodiment, showing the cross-section corresponding to Figure 6. Referring to Figure 10, strain gauge 2B differs from strain gauge 2A (see Figure 9) in that electrode 40B is replaced with electrode 40C. Also, it differs from strain gauge 2 (see Figure 6, etc.) in that the cover layer 60 is provided to cover almost the entire portion excluding electrode 40C.

[0082] The electrode 40C has a laminated structure in which multiple metal layers are stacked. Specifically, the electrode 40C has terminal portions 41 extending from both ends of the resistor 30, a metal layer 42 formed on the upper surface of the terminal portions 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 can be the same as, for example, the same as the metal layers 44 and 45. Note that metal layer 44A is a typical example of the second metal layer according to the present invention.

[0083] To form electrode 40C, first, in the process shown in Figure 7(d), a metal layer 43 is formed by electroplating using, for example, a seed layer 420 as a power supply path. Then, without forming metal layer 44, the resist 800 is removed in the same manner as in the process shown in Figure 8(a), and then the same process as in Figures 8(b) to 8(d) is performed. After that, for example, a metal layer 45A can be formed on the top and side surfaces of metal layer 43 and on the side surfaces of metal layer 42 by electroless plating. Furthermore, for example, a metal layer 44A can be formed on the top and side surfaces of metal layer 45A by electroless plating.

[0084] Thus, electrodes can be manufactured by appropriately using electroplating and electroless plating in combination. In the structure of electrode 40C, a metal layer 43 made of a thick film (1 μm or more) of Cu, Cu alloy, Ni, or Ni alloy is formed on the terminal portion 41, and further, a metal layer 44A made of a material (Au or Pt) with better solder wettability than the metal layer 43 is formed on the outermost layer. However, since the outermost metal layer 44A is formed not only on the upper surface of the metal layer 43 but also on the sides of the metal layers 42 and 43 via a metal layer 45A, the effect of preventing oxidation and corrosion of the Cu, Cu alloy, Ni, or Ni alloy constituting the metal layer 43 can be further improved, and the solder wettability can be further improved, compared to electrodes 40A and 40B.

[0085] Furthermore, the same effect can be obtained by forming the metal layer 44A directly on the top and side surfaces of the metal layer 43 and the side surfaces of the metal layer 42 without forming the metal layer 45A. In other words, the metal layer 44A only needs to directly or indirectly cover the top and side surfaces of the metal layer 43 and the side surfaces of the metal layer 42.

[0086] <Third Embodiment> The third embodiment shows an example of a sensor module using strain gauges. In the third embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

[0087] Figure 11 is a cross-sectional view illustrating a sensor module according to the third embodiment, showing the cross-section corresponding to Figure 2. Referring to Figure 11, the sensor module 5 includes a strain gauge 1, a strain generating body 110, and an adhesive layer 120. The cover layer 60 may be provided to cover the entire portion excluding the terminal portion 41.

[0088] In the sensor module 5, the upper surface 110a of the strain generating body 110 is fixed to the lower surface 10b of the base material 10 via an adhesive layer 120. The strain generating body 110 is formed from 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 the applied force. The strain gauge 1 can detect the strain generated in the strain generating body 110 as a change in the resistance value of the resistor 30.

[0089] The adhesive layer 120 is not particularly limited as long as it is made of a material that has the function of fixing the strain gauge 1 and the strain generating body 110, and can be appropriately selected according to the purpose. For example, epoxy resin, modified epoxy resin, silicone resin, modified silicone resin, urethane resin, modified urethane resin, etc. can be used. Alternatively, materials such as bonding sheets may be used. The thickness of the adhesive layer 120 is not particularly limited and can be appropriately selected according to the purpose, but for example, it can be about 0.1 μm to 50 μm.

[0090] To manufacture the sensor module 5, after fabricating the strain gauge 1, one of the above materials, which will serve as the adhesive layer 120, is applied to the lower surface 10b of the base material 10 and / or the upper surface 110a of the strain generating body 110. Then, the lower surface 10b of the base material 10 is placed opposite the upper surface 110a of the strain generating body 110, and the strain gauge 1 is placed on the strain generating body 110 with the applied material in between. Alternatively, a bonding sheet may be sandwiched between the strain generating body 110 and the base material 10.

[0091] Next, the strain gauge 1 is pressed against the strain generating body 110 and heated to a predetermined temperature to harden the applied material and form an adhesive layer 120. This fixes the upper surface 110a of the strain generating body 110 and the lower surface 10b of the base material 10 via the adhesive layer 120, completing the sensor module 5. The sensor module 5 can be applied to measuring, for example, load, pressure, torque, acceleration, etc.

[0092] In addition, in the sensor module 5, strain gauges 1A, 2, 2A, or 2B may be used instead of strain gauge 1.

[0093] [Example 1] First, as a preliminary experiment, a Ti functional layer 20 was vacuum-deposited onto the upper surface 10a of a substrate 10 made of polyimide resin with a thickness of 25 μm using conventional sputtering. At this time, five samples were prepared in which Ti was deposited with multiple target thicknesses.

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

[0095] Next, as Example 1, a functional layer 20 made of Ti with a thickness of 3 nm was vacuum-deposited onto the upper surface 10a of a substrate 10 made of polyimide resin with a thickness of 25 μm using conventional sputtering.

[0096] Next, a Cr multiphase film was deposited on the entire upper surface of the functional layer 20 as the resistor 30 and terminal portion 41 using magnetron sputtering. Then, the functional layer 20, the resistor 30, and the terminal portion 41 were patterned by photolithography as shown in Figure 1.

[0097] As Comparative Example 1, a Cr multiphase film was deposited on the upper surface 10a of a substrate 10 made of polyimide resin with a thickness of 25 μm, without forming a functional layer 20, using magnetron sputtering, to form a resistor 30 and a terminal portion 41. The film was then patterned as shown in Figure 1 by photolithography. The film deposition conditions for the resistor 30 and terminal portion 41 were identical for both the sample in Example 1 and the sample in Comparative Example 1.

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

[0099] The diffraction peak in Example 1 is located near the diffraction line of α-Cr(110), suggesting that the provision of the Ti functional layer 20 promoted the crystal growth of α-Cr, resulting in the formation of a Cr multiphase film mainly composed of α-Cr.

[0100] Next, multiple samples were prepared from both Example 1 and Comparative Example 1, and their gauge characteristics were measured. As a result, the gauge ratio of each sample from Example 1 was 14-16, while the gauge ratio of each sample from Comparative Example 1 was less than 10.

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

[0102] In this way, by providing a functional layer 20 made of Ti, the crystal growth of α-Cr was promoted, forming a Cr multiphase film mainly composed of α-Cr. As a result, a strain gauge was fabricated with a gauge factor of 10 or higher and a gauge factor temperature coefficient TCS and resistance temperature coefficient TCR within the range of -1000 ppm / °C to +1000 ppm / °C. It is thought that the diffusion effect of Ti into the Cr multiphase film contributed to the improvement of the gauge characteristics.

[0103] [Example 2] In Example 2, multiple substrates 10 made of polyimide resin with different thermal expansion coefficients and a thickness of 25 μm were prepared, and when a Cr multiphase film was deposited as a resistor 30, the relationship between the thermal 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 the resistor 30 was estimated by measuring the warpage of the evaluation sample and using Stoney's equation shown in equation (1). As can be seen from equation (1), the internal stress of the resistor 30 shown in Figure 14 is a value per unit thickness and does not depend on the thickness of the resistor 30.

[0105]

number

[0106] As shown in Figure 14, by setting the thermal expansion coefficient of the base material 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 functions at its limit of warping, and was determined experimentally by the inventors.

[0107] In other words, if the thermal expansion coefficient of the base material 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 rendering it inoperable as a strain gauge. Therefore, the thermal expansion coefficient of the base material 10 must be within the range of 7 ppm / K to 20 ppm / K. Note that the material of the base material 10 does not necessarily have to be polyimide resin.

[0108] By selecting the materials for the base material 10, selecting the materials for the fillers contained in the base material 10, and adjusting their content, the expansion coefficient of the base material 10 can be set to a range of 7 ppm / K to 20 ppm / K.

[0109] In this way, by setting the thermal expansion coefficient of the base material 10 within the range of 7 ppm / K to 20 ppm / K, the difference in expansion rates between the base material 10 and the resistor 30, as well as 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, the 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 made of polyimide resin with a thickness of 25 μm and containing filler were prepared. Three samples each were prepared: one without heat treatment, one with heat treatment at 100°C, one with heat treatment at 200°C, and one with heat treatment at 300°C. After returning to room temperature, the surface irregularities of the upper surface 10a of each substrate 10 were measured using three-dimensional optical interferometry.

[0111] Next, a resistor 30 with a thickness of 0.05 μm was deposited on the upper surface 10a of each substrate 10 by magnetron sputtering, and after patterning as shown in Figure 1 by photolithography, the number of pinholes generated in the resistor 30 was measured by optical transmission, where 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 generated in the resistor 30 is summarized in Figure 15. In Figure 15, the bar graph shows the surface irregularities, and the line graph shows the number of pinholes. The horizontal axis, 100°C, 200°C, and 300°C, represent the temperatures at which the substrate 10 was heat-treated, and "untreated" indicates that it was not heat-treated.

[0113] Figure 15 shows that by heat-treating the substrate 10 at a temperature between 100°C and 300°C, the surface irregularities of the upper surface 10a of the substrate 10 become 15 nm or less, which is about half of the untreated surface, and as a result, the number of pinholes in the resistor 30 is drastically reduced to about 1 / 7. However, considering the heat resistance temperature of the polyimide resin, heat treatment at temperatures exceeding 250°C may cause alteration or deterioration. Therefore, it is preferable to perform the heat treatment at a temperature between 100°C and 250°C. It is thought that the reduction in surface irregularities due to heat treatment is because the polyimide resin constituting the substrate 10 incorporates fillers into its interior during thermal shrinkage caused by the heat treatment.

[0114] According to the inventors' investigation, the number of pinholes in the untreated material (approximately 140) shown in Figure 15 is at a level that degrades 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 using a resistor 30 with a film thickness of 0.05 μm, it was confirmed that by making the surface irregularities of the upper surface 10a of the substrate 10 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.

[0115] Furthermore, even when using a resistor 30 with a film thickness greater than 0.05 μm, it goes without saying that by making the surface irregularities of the upper surface 10a of the substrate 10 15 nm or less, the number of pinholes occurring in the resistor 30 can be reduced to a level that does not adversely affect the gauge characteristics. In other words, by making the surface irregularities of the upper surface 10a of the substrate 10 15 nm or less, the number of pinholes occurring in the resistor 30 can be reduced to a level that does not adversely affect the gauge characteristics when using a resistor 30 with a film thickness of 0.05 μm or more.

[0116] In this way, by heat-treating the substrate 10, the surface irregularities of the upper surface 10a of the substrate 10 can be reduced to 15 nm or less, and as a result, the number of pinholes occurring in the resistor 30 with a film thickness of 0.05 μm or more can be significantly reduced. As a result, the strain gauge 1 can be made to function stably while maintaining good gauge characteristics.

[0117] Furthermore, in order to reduce the number of pinholes that occur in the resistor 30, it is important to reduce the surface irregularities of the upper surface 10a of the substrate 10, and the method of reducing the surface irregularities is not important. Although the method of reducing surface irregularities by applying heat treatment was shown above, it is not limited to this, and any method that can reduce the surface irregularities of the upper surface 10a of the substrate 10 may be used.

[0118] Surface irregularities on the upper surface 10a of the substrate 10 can be reduced by methods such as irradiating the upper surface 10a of the substrate 10 approximately perpendicular to the surface to remove protrusions, moving a water cutter or the like parallel to the upper surface 10a of the substrate 10 to remove protrusions, polishing the upper surface 10a of the substrate 10 using a grinding wheel, or heating and pressing the substrate 10 (heat press).

[0119] Furthermore, in order to reduce the number of pinholes occurring in the resistor 30, it is important to reduce the surface irregularities of the upper surface 10a of the substrate 10. This is not necessarily limited to surface irregularities caused by the presence of fillers, but it is also effective to reduce surface irregularities not caused by the presence of fillers using the various methods described above. For example, if the surface irregularities of a substrate 10 that does not contain fillers are greater than 15 nm, by using the various methods described above to reduce the surface irregularities of the upper surface 10a of the substrate 10 to 15 nm or less, the number of pinholes occurring in the 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.

[0120] [Example 4] In Example 4, the process shown in Figures 7 and 8 was modified as in Modification 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 checked. 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. Ten types of samples were prepared (Samples No. 1 to No. 10) with varying thicknesses for each metal layer, and the presence or absence of solder erosion was checked.

[0121] The results are shown in Table 1. In Table 1, a film thickness of '0' indicates that the metal layer was not formed. '×' indicates that solder erosion occurred during the first soldering attempt. '〇' indicates that no solder erosion occurred during the first soldering attempt, but slight solder erosion occurred during the second soldering attempt (assuming rework of the soldering). '◎' indicates that no solder erosion occurred during either the first or second soldering attempt.

[0122] [Table 1] As shown in Table 1, it was confirmed that solder erosion was improved by increasing the thickness of Cu to 1 μm or more, and further improved by increasing it to 3 μm or more. Furthermore, from the results of Sample 1 and Sample 5, it was confirmed that the presence or absence of solder erosion depended only on the thickness of Cu 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 (Pt, etc.) is necessary to prevent solder erosion and improve solder wettability.

[0123] <Fourth Embodiment> The fourth embodiment shows an example of a sensor with a different structure from that of the first embodiment. In the fourth embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

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

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

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

[0127] The cover layer 60 described in the first practical embodiment may be provided on the upper surface 10a of the base material 10 so as to cover the resistor 30 of each individual sensor 70 and expose the terminal portion 41. Providing the cover layer 60 prevents mechanical damage to the resistor 30 of each individual sensor 70. In addition, providing the cover layer 60 protects the resistor 30 of each individual sensor 70 from moisture and the like. The cover layer 60 may be provided so as to cover the entire portion excluding the terminal portion 41.

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

[0129] Thus, the state of the object to be measured may be detected using a sensor 6A, which is an assembly of individual sensors 70 (strain gauges). This may improve convenience compared to using multiple individual strain gauges 1. The state of the object to be measured refers to the strain, expansion, contraction, deformation, etc. of the object to be measured.

[0130] <Fifth Embodiment> The fifth embodiment shows an example of a sensor capable of acquiring three-dimensional information. In the fifth embodiment, descriptions of components identical to those described in the previously described embodiments may be omitted.

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

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

[0133] The resistor 30B includes a plurality of resistive sections 31B and 32B laminated via the substrate 10. In other words, the resistor 30B is a collective term for the plurality of resistive sections 31B and 32B, and is referred to as the resistor 30B when there is no need to distinguish between the resistive sections 31B and 32B. For convenience, in Figure 18, the resistive sections 31B and 32B are shown with a textured surface.

[0134] Multiple resistive sections 31B are thin films arranged side by side in the Y direction at predetermined intervals on the upper surface 10a of the substrate 10, with their longitudinal direction oriented in the X direction. Multiple resistive sections 32B are thin films arranged side by side in the X direction at predetermined intervals on the lower surface 10b of the substrate 10, with their longitudinal direction oriented in the Y direction. However, the multiple resistive sections 31B and the multiple resistive sections 32B do not need to be orthogonal in a plan view; they only need to intersect.

[0135] The width of the resistor 30B is not particularly limited and can be appropriately selected depending on the purpose, but for example it can be approximately 0.1 μm to 1000 μm (1 mm). The pitch between adjacent resistors 30B is not particularly limited and can be appropriately selected depending on the purpose, but for example it can be approximately 1 mm to 100 mm. In Figures 18 and 19, 10 resistors 31B and 10 resistors 32B are shown, but the number of resistors 31B and 32B can be appropriately changed 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 portion 41B extends from both ends of each resistor portion 31B on the upper surface 10a of the base material 10, and in a plan view, it is wider than the resistor portion 31B and formed in a roughly rectangular shape. The terminal portion 41B is a pair of electrodes for outputting to the outside the change in the resistance value of the resistor portion 31B according to the state of the object to be measured, and for example, a flexible substrate or lead wire for external connection is joined to it. The upper surface of the terminal portion 41B may be covered with a metal that has better solderability than the terminal portion 41B. Although the resistor portion 31B and the terminal portion 41B are given different reference numerals for convenience, both can be formed integrally from the same material in the same process.

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

[0138] Alternatively, through-holes (through wiring) may be provided that penetrate the base material 10, and terminal sections 41B and 42B may be concentrated 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 practical embodiment may be provided on the upper surface 10a of the base material 10 so as to cover the resistor portion 31B and expose the terminal portion 41B. Alternatively, the cover layer 60 described in the first practical embodiment may be provided on the lower surface 10b of the base material 10 so as to cover the resistor portion 32B and expose the terminal portion 42B. Providing the cover layer 60 prevents mechanical damage to the resistor portions 31B and 32B. Furthermore, providing the cover layer 60 protects the resistor portions 31B and 32B from moisture and other elements. The cover layer 60 may be provided so as to cover the entire portion excluding the terminal portions 41B and 42B.

[0140] As shown in Figure 20, the sensor module 8 can be realized by the sensor 6B and the control device 7. In the sensor module 8, the sensor 6B is attached to the object to be measured, and the control device 7 can detect the state of the object to be measured. Multiple sensors 6B may be attached to the object to be measured.

[0141] In the sensor module 8, the respective terminals 41B and 42B of the sensor 6B are connected to the control device 7 using, for example, a flexible circuit board or lead wires.

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

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

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

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

[0146] In other words, one side of the bridge circuit is composed of a resistor between a pair of electrodes selected by the input signal selection switch, and the other three sides are composed of fixed resistors. As a result, the output of the bridge circuit can be a voltage (analog signal) corresponding to the resistance value of the resistor between the 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, then 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, a temperature-compensated digital signal is sent to the signal processing unit 72. By rapidly switching the input signal selection switch, digital signals corresponding to the resistance values ​​of all terminals 41B and 42B of the sensor 6B can be sent to the signal processing unit 72 in a very short time.

[0148] 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 based on the information sent from the analog front-end unit 71.

[0149] Furthermore, if the resistance values ​​of multiple resistors 31B or multiple resistors 32B change, it is possible to detect that the sensor 6B has been pressed at multiple locations.

[0150] In cases where the pressing force is small, only the resistance part 31B and 32B closer to the side being pressed may be pressed, while the resistance part further away from the side being pressed may not be pressed. In this case, only the resistance value between the pair of electrodes of the resistance part closer to the side being pressed changes continuously in accordance with the magnitude of the pressing force. 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 resistance part closer to the side being pressed.

[0151] In other words, when the resistor 31B and / or resistor 32B are pressed, the resistance value between the pair of electrodes of the pressed resistor (resistor 31B and / or resistor 32B) changes continuously according to the magnitude of the pressing force. The signal processing unit 72 can then 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 can be configured to include, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), main memory, etc.

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

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

[0155] As a result, when the resistance parts 31B and 32B are pressed, the pressed resistance parts 31B and 32B bend in accordance with the pressing force, and the resistance value between the pair of electrodes of the pressed resistance parts 31B and 32B changes continuously according to the magnitude of the pressing force. In other words, by using the sensor 6B, three-dimensional information (the coordinates of the pressed position and the magnitude of the pressing force) can be obtained. That is, information about the entire object being measured can be obtained, and the areas where the state of the object being measured is changing can be grasped in detail, making it possible to detect the state of the object being measured with high accuracy.

[0156] In particular, when the resistive parts 31B and 32B are formed from a Cr multiphase film, the sensitivity of the resistance value to the pressing force (the amount of change in the resistance value of the resistive parts 31B and 32B for the same pressing force) is significantly improved compared to when the resistive parts 31B and 32B are formed from Cu-Ni or Ni-Cr. When the resistive parts 31B and 32B are formed from a Cr multiphase film, the sensitivity of the resistance value to the pressing force is approximately 5 to 10 times higher than when the resistive parts 31B and 32B are formed from Cu-Ni or Ni-Cr. Therefore, by forming the resistive parts 31B and 32B from a Cr multiphase 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 pressing force makes it possible to implement control such that a predetermined action is performed when a small pressing force is detected, another action is performed when a medium pressing force is detected, and yet another action is performed when a large pressing force is detected. Alternatively, it is possible to implement control that does not perform any action when a small or medium pressing force is detected, and only performs a predetermined action when a large pressing force is detected.

[0158] Furthermore, a high sensitivity of the resistance value to the pressing force allows for the acquisition of a signal with a high signal-to-noise ratio (S / N). Therefore, accurate signal detection is possible even when 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 an even faster speed. As a result, even fast movements input to the sensor module 8 can be detected.

[0159] Furthermore, if the resistor 30B is formed from a Cr multiphase film, the sensor 6B can be miniaturized, thereby increasing the flexibility in selecting its placement location.

[0160] <Modification 1 of the Fifth Embodiment> Modification 1 of the fifth embodiment shows an example in which the resistance portion of the sensor is made into a zigzag pattern. Note that in Modification 1 of the fifth embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

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

[0162] The resistor 30C includes resistive sections 31C and 32C. Resistive section 31C is a zigzag pattern formed between a pair of terminal sections 41B. Resistive section 32C is a zigzag pattern formed between a pair of terminal sections 42B. The material and thickness of resistive sections 31C and 32C can be the same as, for example, the material and thickness of resistive sections 31B and 32B.

[0163] In this way, by making the resistance sections 31C and 32C a zigzag pattern, the resistance values ​​between a pair of terminal sections 41B and a pair of terminal sections 42B can be increased compared to when they are arranged in a linear pattern. As a result, the amount of change in the resistance values ​​between a pair of terminal sections 41B and a pair of terminal sections 42B when pressed becomes larger, which further improves the accuracy of detecting the coordinates of the pressed position and allows for even more sensitive detection of force.

[0164] Furthermore, since the resistance values ​​between the pair of terminals 41B and the pair of terminals 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 multiphase film is used as the material for the resistor 30 in the strain gauge according to the first embodiment. In the sixth embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

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

[0167] For example, while conventional strain gauges have an output of approximately 0.04mV / 2V, strain gauge 3 can achieve an output of 0.3mV / 2V or higher. Furthermore, while conventional strain gauges have a size (gauge length × gauge width) of approximately 3mm × 3mm, strain gauge 3 can be miniaturized to approximately 0.3mm × 0.3mm.

[0168] Strain gauges are generally used by attaching them to a strain-generating material (such as metal). Conventional strain gauges had low sensitivity, which imposed design limitations on the material selection of the strain-generating material in order to ensure sensor characteristics.

[0169] In contrast, strain gauge 3 is more sensitive than conventional strain gauges, which significantly reduces the design limitations associated with using conventional strain gauges and improves the freedom of material selection for the strain-generating body.

[0170] Furthermore, because strain gauge 3 is smaller than conventional strain gauges, it can be installed in minute measurement locations where it was previously impossible to use conventional strain gauges.

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

[0172] Furthermore, because strain gauge 3 is lightweight and can be attached to the location to be measured, it has the advantage of being able to directly measure the desired location compared to MEMS (Micro Electro Mechanical Systems) sensors and other devices that require mounting on an electronic circuit board and are used for similar measurements.

[0173] Furthermore, since strain gauge 3 is extremely small and its mass is negligible, it is unaffected by inertia and exhibits excellent sensitivity, stability, and fatigue life.

[0174] Furthermore, the strain gauge 3 can also perform self-temperature compensation, in which case it can be used for any object with diverse thermal expansion coefficients, regardless of whether it is metal or plastic.

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

[0176] Based on the characteristics described above, strain gauge 3 has a wide range of applications. Specific examples of strain gauge 3 applications are shown below. <First Application Example> The aerodynamic resistance of an automobile is invisible, unstable, and difficult to measure. Therefore, it is difficult to understand the downforce and lift aerodynamic diagrams generated on the vehicle body. In the first application example, considering these points, we demonstrate an example of detecting wind pressure and other factors experienced by a moving automobile using a strain gauge 3.

[0177] Figure 23 is a schematic diagram illustrating the airflow when a car is in motion. When car 500 is in motion, an airflow like the one shown by the arrow in Figure 23 is generated. Due to this airflow, if the speed at which car 500 is traveling increases, lift will act on the car body, causing it to try to lift off the ground and potentially making the vehicle unstable.

[0178] Therefore, the automobile 500 has a front spoiler 510, side spoilers 520, and a rear spoiler (rear wing) 530. By having the front spoiler 510, side spoilers 520, and rear spoiler 530, the automobile 500 generates downforce in the direction of the arrow, reducing the lift acting on the vehicle body even when speed is increased, suppressing the vehicle body from floating, and enabling stable driving.

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

[0180] The strain gauge 3 may be attached to or embedded in at least one surface of the front spoiler 510A, the side spoiler 520A, and the rear spoiler (rear wing) 530A, for example. Alternatively, an air intake may be placed in at least one of the front spoiler 510A, the side spoiler 520A, and the rear spoiler (rear wing) 530A, and the strain gauge 3 may be attached to or embedded in the area where the intake airflow is concentrated.

[0181] In this way, by attaching strain gauge 3 to the spoiler, it becomes 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), the E-Cockpit display, the head-up display, etc., it becomes possible to visualize the downforce acting on the vehicle and quantify the aerodynamic diagram.

[0183] While spoilers are often made of resin to reduce weight, the strain gauge 3, formed on a flexible base material, 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 variable by a motor or the like, it is possible to optimize the lift and downforce acting on the vehicle body by varying the spoiler based on the wind pressure detected by the strain gauge 3, thereby achieving more stable driving.

[0185] As described above, the strain gauge 3 is highly sensitive, allowing for easy detection of wind pressure acting on the spoiler. Furthermore, displaying the detection results on a screen enables visualization of airflow, such as downforce. By feeding back the detection results of the strain gauge 3 to the variable spoiler, the lift and downforce acting on the vehicle body can be actively controlled, resulting in more stable driving. Additionally, converting the detection results into the degree of impact on fuel efficiency due to air resistance and displaying it on the screen enables visualization of fuel efficiency information. The strain gauge 3 can be used not only in engine-driven vehicles but also in electric vehicles and hybrid vehicles.

[0186] Note that strain gauge 3 may be used individually or in multiple units. Alternatively, strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C, which use a Cr multiphase film as the resistive material, may be used instead of strain gauge 3. <Second Application Example> Automobile accelerator pedals are made of highly rigid materials (materials that are difficult to bend), and conventional strain gauge sensors could not accurately sense the pedal pressure as auxiliary sensors. In other words, conventional strain gauges have low sensitivity and could only measure components made of easily bendable materials. Alternatively, when measuring components made of highly rigid materials (materials that are difficult to bend), a strain-generating body made of a less rigid material (a material that is easy to bend) was attached to the object being measured. In the second application example, in consideration of these points, we will show an example of detecting the pedal pressure of an accelerator pedal using strain gauge 3.

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

[0188] By attaching a strain gauge 3 to the accelerator pedal 540, the force applied to the accelerator pedal 540 can be detected. By using a highly sensitive strain gauge 3, even if the accelerator pedal 540 is made of a highly rigid material (a material that is difficult to bend), highly sensitive sensing is possible, and the force applied to the pedal can be detected more accurately.

[0189] As described above, the strain gauge 3 is highly sensitive, so even when the accelerator pedal 540 is made of a highly rigid material (a material that does not bend easily), it is possible to detect the pressing force with high accuracy. This is expected to improve the speed control and fuel efficiency of the vehicle.

[0190] Note that strain gauge 3 may be used individually or in multiple units. Alternatively, strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C, which use a Cr multiphase film as the resistive material, may be used instead of strain gauge 3. <Third Application Example> The grip force applied to a car's steering wheel can be detected, for example, by a dedicated sensor placed on the steering wheel. For example, the dedicated sensor can be placed in two symmetrical locations that are easily gripped, and the grip force at these locations can be detected. The dedicated sensor can be placed, for example, between the steering wheel's core material and its exterior, but such placement can compromise the design aesthetics of the steering wheel in some high-end cars. The third application example, in light of these points, is an example of detecting the steering wheel's grip force using a strain gauge 3.

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

[0192] The steering wheel 550X in the comparative example shown in Figure 26 has a structure in which the outer circumference of a metal core material 551 is covered with a resin 552 such as urethane, a dedicated sensor 3X for detecting grip force is placed so as to be attached to the outer circumference of the resin 552, and the outer circumference of the dedicated sensor 3X is covered with an outer casing 553 made of leather or the like. The dedicated sensor 3X is placed, for example, in two symmetrical locations on the left and right sides of the annular steering wheel 550X where it is easy to grip.

[0193] Because the dedicated sensor 3X has lower sensitivity compared to the strain gauge 3, sensing is difficult when it is attached inside the metal core material 551, which is resistant to deformation. Therefore, in the steering 550X, the dedicated sensor 3X is attached to the outer circumference of the resin 552, which is easily deformable.

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

[0195] Furthermore, as shown in Figure 28, by arranging the strain gauges 3 around the entire circumference of the steering wheel 550, it becomes possible to detect grip force in a 360° direction. In this case, for example, grip force can be detected not only during normal operation as shown in Figure 29(a), but also when gripping various positions on the steering wheel 550, such as when making steering changes as shown in Figures 29(b) and 29(c). However, the strain gauges 3 do not necessarily need to be arranged around the entire circumference of the steering wheel 550; they only need to be arranged on at least a part of the steering wheel 550.

[0196] Thus, because the strain gauge 3 is highly sensitive, it is possible to detect the grip force even when it is attached inside the rigid core material 551. Furthermore, since attaching the strain gauge 3 inside the core material 551 does not affect the design of the steering wheel 550, the design of the steering wheel 550 is improved.

[0197] Furthermore, by arranging highly sensitive strain gauges 3 around the entire circumference of the steering wheel 550, it becomes possible to detect grip force even during steering operations involving changes in direction, such as turning right, turning left, or curving.

[0198] Note that strain gauge 3 may be used individually or in multiple units. Alternatively, strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C, which use a Cr multiphase film as the resistive material, may be used instead of strain gauge 3. <Fourth Application Example> Automotive door handles are used as a key slot for the door lock and as a grip for opening and closing the door. However, in some luxury cars, the handle detracts from the car's design, and the removal of door handles is being considered. Furthermore, door handles have the disadvantage of being easily scratched due to their uneven surface. In the fourth application example, in consideration of these points, we present an example of a door handle-less door that uses strain gauge 3 to unlock the door.

[0199] Figure 30 is a perspective view showing an example of a strain gauge 3 being attached to a car door. Figure 31 is a cross-sectional view showing an example of a strain gauge 3 being attached to a car door. The door 560 shown in Figures 30 and 31 has an inner panel 561 and an outer panel 562, and does not have a door handle. The 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 the strain gauge 3 at a predetermined position on the outer panel 562 side of the door 560, it is possible to detect when that predetermined position is pressed, thereby releasing the door lock. For example, if the structure is designed to open and close the door using power such as a motor, when it is detected that the predetermined position to which the strain gauge 3 is attached is pressed, the door lock can be released using power such as the motor and the door can be opened.

[0201] By positioning the strain gauge 3 at a predetermined location on the outer panel 562 side of the door 560, sensing becomes possible from the inside of the outer panel 562, thus avoiding any compromise to the vehicle's design. Furthermore, because the strain gauge 3 is highly sensitive, reliable detection of door lock release is possible.

[0202] For example, strain gauges 3 may be placed at multiple locations on the outer panel 562, and the door lock may be released and the door opened or closed when the strain gauges 3 placed at multiple locations are pressed in a predetermined specific order. This prevents false detections and ensures that only specific individuals can release the door lock and open or close the door, making it possible to use it as door lock authentication.

[0203] Alternatively, the sensor 6B (see Figures 18 and 19) may be placed at a predetermined position on the outer panel 562, and the sensor 6B may be configured to detect when a specific input pattern is traced by a finger or the like. In this case as well, false detections can be prevented, and only specific individuals can unlock the door lock and open and close the door, making it possible to use it as door lock authentication.

[0204] Thus, by using strain gauge 3, door handles become unnecessary for opening and closing the doors, and the freedom of body design is increased, making it possible to design the beautiful form that some luxury cars aim for. Furthermore, it becomes possible to propose a new opening and closing system that is less likely to cause scratches when opening and closing the doors.

[0205] Note that strain gauge 3 may be used individually or in multiple units. Alternatively, strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C, which use a Cr multiphase film as the resistive material, may be used instead of strain gauge 3. <5th Application Example> Electronic Stability Control (ESC), which detects unstable vehicle posture such as oversteer and understeer, is an active safety system that controls the basic performance of a car, "turning." For example, tilt sensors were used in ESCs. Specifically, "pendulum type" and "float type" tilt sensors were used to detect the deviation between a weight suspended in the direction of gravity or a liquid surface and an inclined object. MEMS type acceleration sensors and gyroscopes (angular velocity sensors) were also used. However, tilt sensors had problems in terms of accuracy, and acceleration sensors and gyroscopes (angular velocity sensors) were expensive, posing a problem in terms of cost. In the fifth application example, in consideration of these points, we will show an example of detecting the posture of a vehicle using strain gauge 3.

[0206] Figure 32 is a perspective view showing an example of a 6-axis force sensor having strain gauges 3. The 6-axis force sensor 570 shown in Figure 32 has a strain generating body 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 placed side by side on each face of each beam 573, for a total of 32 strain gauges 3. However, the shape of the outer frame 572 and beams 573 of the strain generating body 571 and the number of strain gauges 3 are examples only and are not limited to these.

[0208] In the 6-axis force sensor 570, the intersections of the four beams 573, which are arranged to form a cross, serve as sensing elements, and weights 574 are fixed to these sensing elements. As a result, the 6-axis force sensor 570 can detect translational forces in three axial directions and couples with a single sensor.

[0209] The 6-axis force sensor 570 can be positioned, for example, near the center of gravity G of the automobile 500B shown in Figure 33. This allows the weight 574 of the 6-axis force sensor 570 to tilt in response to the posture of the automobile 500B, enabling the detection of vertical, horizontal, forward, yawing, pitching, and rolling motions of the automobile 500B, thereby enabling posture control of the vehicle body.

[0210] Thus, by using the 6-axis force sensor 570 with strain gauges 3 as a sensor for controlling the vehicle's attitude, a simple ESC can be constructed, enabling the realization of an inexpensive and safe ESC system. Furthermore, by using the highly sensitive strain gauges 3, even slight attitude deviations such as oversteer and understeer can be detected, making it possible to easily realize an inexpensive and safe ESC system.

[0211] Furthermore, the attitude control in the fifth application example may be used in conjunction with the control of the variable spoiler in the first application example. For example, by controlling the variable spoiler so that the attitude of the vehicle body detected by the 6-axis force sensor 570 is stable, accidents such as the vehicle 500B overturning due to strong winds can be prevented.

[0212] Note that strain gauge 3 may be used individually or in multiple units. Alternatively, strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C, which use a Cr multiphase film as the resistive material, may be used instead of strain gauge 3. <Sixth Application Example> The sixth application example shows how to detect the operating state of a wiper using a strain gauge 3.

[0213] Figure 34 is a schematic diagram showing an example of attaching strain gauges 3 to a car's windshield wiper. In Figure 34, 380 are two wipers, and strain gauges 3 are attached to the surface of each wiper 580. Alternatively, the strain gauges 3 may be embedded in the wiper 580.

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

[0215] Furthermore, the operating speed of the wiper 580 can be varied based on the detection results of the strain gauge 3. Alternatively, the wiper 580 can be designed with a variable angle for the rubber portion, and the angle of the rubber portion can be varied based on the detection results of the strain gauge 3 to improve the sliding state and the state of uneven wiping. In addition, wear of the rubber portion of the wiper 580 can be detected based on the detection results of the strain gauge 3.

[0216] Note that strain gauge 3 may be used individually or in multiple units. Alternatively, strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C, which use a Cr multiphase film as the resistive material, may be used instead of strain gauge 3. <Seventh Application Example> The seventh application example demonstrates how to activate an airbag using strain gauge 3.

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

[0218] By attaching strain gauge 3 to bumper 590, the impact received by the 500C vehicle can be detected, and the airbag can be activated. Alternatively, strain gauge 3 can be attached to the airbag to detect whether the pressure when the airbag deploys is appropriate.

[0219] Note that strain gauge 3 may be used individually or in multiple units. Alternatively, strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C, which use a Cr multiphase film as the resistive material, may be used instead of strain gauge 3. <Application Example 8> The eighth application example demonstrates the use of strain gauge 3 to detect malfunctions in engines and superchargers.

[0220] Figure 36 is a schematic diagram showing an example of placing strain gauges 3 near the engine and supercharger of an automobile. In Figure 36, 610 is the supercharger, 620 is the exhaust turbine, 630 is the intake valve, and 640 is the exhaust valve, with the strain gauges 3 placed near the supercharger 610.

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

[0222] When the engine interior becomes hot, it is preferable to use a highly heat-resistant material such as ceramic (e.g., alumina, zirconia, sapphire) instead of resin as the base material 10 of the strain gauge 3.

[0223] Note that strain gauge 3 may be used individually or in multiple units. Alternatively, strain gauges 1A, 2, 2A, 2B, sensors 6A, 6B, or 6C, which use a Cr multiphase film as the resistive material, may be used instead of strain gauge 3.

[0224] Although preferred embodiments have been described in detail above, the invention is not limited to the embodiments described above, and various modifications and substitutions can be made to the embodiments described above 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 Top 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 generating body, 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 6-axis force sensor, 571 Strain generating 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. It is the accelerator pedal of a car. The system includes a sensor that detects the force applied to the accelerator pedal, The aforementioned sensor is A flexible resin base material, A functional layer formed directly on one surface of the aforementioned substrate from a metal, alloy, or metal compound, On one side of the functional layer, Cr, CrN, and Cr ２ It comprises a resistor mainly composed of α-Cr, formed from a film containing N, The functional layer has the function of promoting the crystal growth of α-Cr and forming a film mainly composed of α-Cr. 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. An accelerator pedal that detects the pressing force of the accelerator pedal as a change in the resistance value of the resistor.

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

3. The aforementioned accelerator pedal is The accelerator pedal according to claim 1 or 2, which is formed of a material with high rigidity.

4. The resistor is A plurality of first resistors are arranged side by side on one side of the substrate with their longitudinal direction oriented in a first direction, The accelerator pedal according to any one of claims 1 to 3, further comprising: a plurality of second resistive portions arranged side by side on the other side of the base material with their longitudinal direction intersecting the first direction;

5. It is the steering wheel of a car, The system includes a sensor for detecting the grip force of the steering wheel, The aforementioned sensor is A flexible resin base material, A functional layer formed directly on one surface of the aforementioned substrate from a metal, alloy, or metal compound, On one side of the functional layer, Cr, CrN, and Cr ２ It comprises a resistor mainly composed of α-Cr, formed from a film containing N, The functional layer has the function of promoting the crystal growth of α-Cr and forming a film mainly composed of α-Cr. 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. A steering system that detects the grip force of the steering system as a change in the resistance value of the resistor.

6. A core material formed from a highly rigid material, The core material has a resin covering the outer periphery, The aforementioned sensor is The steering wheel according to claim 5, provided inside the core material.

7. The aforementioned sensor is The steering wheel according to claim 6, which is provided in the entire circumferential direction inside the core material.

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

9. It is a car door, Inner panel and It has an outer panel, The outer panel is provided with a sensor located at a predetermined position on the inside of the outer panel, which detects the pressing force at the predetermined position. The aforementioned sensor is A flexible resin base material, A functional layer formed directly on one surface of the aforementioned substrate from a metal, alloy, or metal compound, On one side of the functional layer, Cr, CrN, and Cr ２ It comprises a resistor mainly composed of α-Cr, formed from a film containing N, The functional layer has the function of promoting the crystal growth of α-Cr and forming a film mainly composed of α-Cr. 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. A door that detects the pressing force of the outer panel as a change in the resistance value of the resistor.

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

11. The resistor is A plurality of first resistors are arranged side by side on one side of the substrate with their longitudinal direction oriented in a first direction, The door according to claim 9 or 10, further comprising a plurality of second resistive portions arranged side by side on the other side of the base material, with their longitudinal direction oriented in a second direction intersecting the first direction.

12. A door according to any one of claims 9 to 11, A door opening and closing system comprising an opening and closing mechanism that opens and closes a door based on the detection of the aforementioned pressing force.

13. A door according to any one of claims 9 to 11, A door opening and closing system comprising: an opening and closing mechanism that releases the door lock or opens and closes the door when multiple 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 or opens / closes a door when the aforementioned sensor is traced with a predetermined specific input pattern, A door opening and closing system equipped with this feature.

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