strain gauge

Abstract

To provide a strain gauge that can precisely adjust the resistance value of a resistor.SOLUTION: The strain gauge includes an insulation layer and a resistor, the resistor including: a first resistance unit formed in one surface side of the insulation layer; a second resistance unit formed in the other surface side of the insulation layer; and a through-hole penetrating the insulation layer, the through-hole electrically connecting the first resistance unit and the second resistance unit to each other, the first resistance unit and the second resistance unit forming the resistor connected by the through-hole and connecting a pair of electrodes to each other. The strain gauge includes a resistance adjusting unit for bridging a part next to the first resistance value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a strain gauge. [Background technology]

[0002] Conventionally, strain gauges that are attached to an object to be measured have been known. For example, strain gauges are sometimes used as sensors that detect strain in materials or sensors that detect ambient temperature (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-221696 Summary of the Invention [Problem to be solved by the invention]

[0004] A strain gauge has a resistor on a substrate. The resistance value of this resistor is preferably adjustable. In order to accurately detect strain in a strain gauge, it is also preferable that the resistance value of the resistor be adjustable with high precision.

[0005] The present invention has been made in view of the above points, and has as its object to provide a strain gauge in which the resistance value of a resistor can be adjusted with high precision. [Means for solving the problem]

[0006] A strain gauge according to an embodiment of the present disclosure includes an insulating layer and a resistor, the resistor including a first resistor portion formed on one surface of the insulating layer, a second resistor portion formed on the other surface of the insulating layer, and a through hole that penetrates the insulating layer and electrically connects the first resistor portion and the second resistor portion, the first resistor portion and the second resistor portion being connected via the through hole to form the resistor that connects between a pair of electrodes, A resistance adjustment section is provided which includes a resistance adjustment pattern formed on one side of the insulating layer, the first resistance section includes a plurality of elongated first portions, each of which is arranged in parallel at a predetermined interval with its longitudinal direction facing the same direction, the first resistance section includes a plurality of electrically independent blocks arranged at a distance from each other, at least one of the plurality of blocks includes a plurality of the first portions, and the resistance adjustment pattern is provided in at least one of the blocks so as to bridge adjacent first portions among the plurality of first portions to provide electrical conductivity. [Effects of the Invention]

[0007] According to the disclosed technique, it is possible to provide a strain gauge in which the resistance value of the resistor can be adjusted with high precision. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a plan view (part 1) illustrating a strain gauge according to a first embodiment. FIG. [Figure 2] 1 is a cross-sectional view (part 1) illustrating a strain gauge according to a first embodiment. FIG. [Figure 3] 4 is a second plan view illustrating the strain gauge according to the first embodiment; FIG. [Figure 4] FIG. 2 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. [Figure 5] FIG. 2 is a plan view illustrating a strain gauge according to a first modified example of the first embodiment. [Figure 6] 10 is a diagram illustrating a current flow in a strain gauge according to Modification 1 of the first embodiment. FIG. [Figure 7] 10 is a plan view (part 1) illustrating a strain gauge according to a second modification of the first embodiment. FIG. [Figure 8] 10 is a second plan view illustrating a strain gauge according to Modification 2 of the first embodiment. FIG. [Figure 9] 10 is a plan view (part 1) illustrating a strain gauge according to a third modified example of the first embodiment. FIG. [Figure 10] 10 is a second plan view illustrating a strain gauge according to a third modified example of the first embodiment. FIG. [Figure 11] 10A and 10B are diagrams illustrating adjustment of the resistance value of a strain gauge 1C. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the invention will be described with reference to the drawings. In each drawing, the same components may be assigned the same reference numerals. Furthermore, in each drawing, mutually orthogonal X, Y, and Z directions may be defined. In this case, in the X direction, the starting point (base) side of the arrow may be referred to as the X- side, and the ending point (arrowhead) side of the arrow may be referred to as the X+ side. The same applies to the Y and Z directions. Furthermore, in the description of each drawing, a description of components that are the same as components already described may be omitted.

[0010] First Embodiment Fig. 1 is a plan view (part 1) illustrating the strain gauge according to the first embodiment. Fig. 2 is a cross-sectional view (part 1) illustrating the strain gauge according to the first embodiment, showing a cross section along line AA in Fig. 1. Fig. 3 is a plan view (part 2) illustrating the strain gauge according to the first embodiment, showing the strain gauge shown in Fig. 1 with the first resistor and electrodes removed for convenience in order to show the pattern of the second resistor.

[0011] 1 to 3, the strain gauge 1 has a substrate 10, a resistor 30, and electrodes 50. The resistor 30 has a first resistive portion 31, a second resistive portion 32, and a through-hole 35. First, each part constituting the strain gauge 1 will be described in detail.

[0012] In this embodiment, for convenience, the side of the strain gauge 1 on which the first resistor 31 of the substrate 10 is provided is referred to as the "upper side," and the side on which the second resistor 32 is provided is referred to as the "lower side." The surface located on the upper side of each portion is referred to as the "upper surface," and the surface located on the lower side of each portion is referred to as the "lower surface." However, the strain gauge 1 can also be used upside down. The strain gauge 1 can also be positioned at any angle. A planar view refers to viewing an object in a normal direction from above to below the upper surface 10a of the substrate 10. A planar shape refers to the shape of the object when viewed in the normal direction.

[0013] The substrate 10 is a member that serves as a base layer for forming the resistor 30 and the like. The substrate 10 is flexible. A flexure element may be bonded to the lower side of the substrate 10 (more specifically, further below the second resistor section 32 described below) via an adhesive layer or the like. The thickness of the substrate 10 is not particularly limited and may be determined appropriately depending on the intended use of the strain gauge 1, etc. For example, the thickness of the substrate 10 may be approximately 5 μm to 500 μm. From the viewpoints of strain transmission from the surface of the flexure element to the sensing section and dimensional stability against environmental changes, the thickness of the substrate 10 is preferably within the range of 5 μm to 200 μm. From the viewpoint of insulation, the thickness of the substrate 10 is preferably 10 μm or more.

[0014] The substrate 10 is 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, LCP (liquid crystal polymer) resin, polyolefin resin, etc. The film refers to a flexible member having a thickness of about 500 μm or less.

[0015] When the substrate 10 is formed from an insulating resin film, the insulating resin film may contain fillers, impurities, etc. For example, the substrate 10 may be formed from an insulating resin film containing fillers such as silica or alumina.

[0016] Materials other than resin for the substrate 10 include, for example, crystalline materials such as SiO2, ZrO2 (including YSZ), Si, Si2N3, Al2O3 (including sapphire), ZnO, and perovskite ceramics (CaTiO3, BaTiO3). In addition to the crystalline materials described above, amorphous glass or the like may also be used as the material for the substrate 10. Metals such as aluminum, aluminum alloys (duralumin), and titanium may also be used as the material for the substrate 10. When a metal is used, an insulating film is provided to cover the upper and lower surfaces of the metallic substrate 10.

[0017] In the resistor 30, the first resistive portion 31 is a thin film formed in a predetermined pattern on the upper side of the substrate 10. In addition, in the resistor 30, the second resistive portion 32 is a thin film formed in a predetermined pattern on the lower side of the substrate 10. The resistor 30 is a sensitive portion that generates a resistance change when subjected to strain. The detailed structure of the resistor 30 will be described later.

[0018] The resistor 30 can be formed from, for example, a material containing Cr (chromium), a material containing Ni (nickel), or a material containing both Cr and Ni. That is, the resistor 30 can be formed from a material containing at least one of Cr and Ni. An example of a material containing Cr is a Cr mixed phase film. An example of a material containing Ni is Cu-Ni (copper-nickel). An example of a material containing both Cr and Ni is Ni-Cr (nickel-chromium).

[0019] Here, the Cr mixed phase film is a film in which Cr, CrN, Cr2N, etc. are mixed together. The Cr mixed phase film may contain inevitable impurities such as chromium oxide.

[0020] The thickness of the resistor 30 is not particularly limited and may be determined appropriately depending on the intended use of the strain gauge 1, etc. For example, the thickness of the resistor 30 may be approximately 0.05 μm to 2 μm. In particular, when the thickness of the resistor 30 is 0.1 μm or more, the crystallinity of the crystals constituting the resistor 30 (for example, the crystallinity of α-Cr) is improved. Furthermore, when the thickness of the resistor 30 is 1 μm or less, (i) cracks in the film and (ii) warping of the film from the substrate 10 caused by internal stress of the film constituting the resistor 30 are reduced.

[0021] Considering the need to reduce lateral sensitivity and to prevent disconnection, the width of resistor 30 is preferably 10 μm to 100 μm. Furthermore, the width of resistor 30 is preferably 10 μm to 70 μm, and more preferably 10 μm to 50 μm. In resistor 30, the width of first resistive portion 31 and the width of second resistive portion 32 may be the same or different.

[0022] For example, when the resistor 30 is a Cr mixed-phase film, the stability of the gauge characteristics can be improved by using α-Cr (alpha chromium), which has a stable crystalline phase, as the main component. Furthermore, when the resistor 30 is a Cr mixed-phase film, the resistor 30 can have an α-Cr main component, thereby enabling the gauge factor of the strain gauge 1 to be 10 or more, and the temperature coefficient of gauge factor (TCS) and the temperature coefficient of resistance (TCR) to be within the range of −1000 ppm / °C to +1000 ppm / °C. Here, the term “main component” refers to a component that accounts for 50% by weight or more of the total material constituting the resistor. From the viewpoint of improving the gauge characteristics, the resistor 30 preferably contains 80% by weight or more of α-Cr. Furthermore, from the same viewpoint, the resistor 30 more preferably contains 90% by weight or more of α-Cr. Note that α-Cr is Cr with a bcc structure (body-centered cubic lattice structure).

[0023] Furthermore, when the resistor 30 is a Cr mixed phase film, the Cr mixed phase film preferably contains 20 wt % or less of CrN and Cr2N, which can suppress a decrease in the gauge factor of the strain gauge 1.

[0024] Furthermore, the ratio of CrN to Cr2N in the Cr mixed phase film is preferably 80 wt% or more but less than 90 wt% of the total weight of CrN and Cr2N. More preferably, the ratio is 90 wt% or more but less than 95 wt% of the total weight of CrN and Cr2N. Cr2N has semiconducting properties. Therefore, by setting the Cr2N ratio to 90 wt% or more but less than 95 wt%, the decrease in TCR (negative TCR) becomes even more pronounced. Furthermore, by setting the Cr2N ratio to 90 wt% or more but less than 95 wt%, the ceramicization of the resistor 30 can be reduced. Therefore, the resistor 30 is less susceptible to brittle fracture.

[0025] On the other hand, CrN also has the advantage of being chemically stable. By including more CrN in the Cr mixed-phase film, the possibility of unstable N occurring can be reduced, resulting in a stable strain gauge. Here, "unstable N" refers to trace amounts of N2 or atomic N that can exist within the Cr mixed-phase film. This unstable N can escape from the film depending on the external environment (e.g., high-temperature environment). When unstable N escapes from the film, the film stress of the Cr mixed-phase film can change.

[0026] The electrodes 50 are a pair of electrodes for outputting a change in the resistance value of the resistor 30 caused by strain to the outside. The electrodes 50 are arranged on the upper surface 10a of the substrate 10, for example, similar to the first resistor portion 31. The electrodes 50 are electrically connected to both ends of the resistor 30. The electrodes 50 are formed in a generally rectangular shape wider than the resistor 30 in a plan view. In the example of FIG. 1 , the electrode 50 located on the Y+ side of the pair of electrodes 50 is connected to the X+ side end of the second resistor portion 32 located closest to the Y+ side via a through hole 35. Furthermore, the electrode 50 located on the Y− side of the pair of electrodes 50 is connected to the X+ side end of the second resistor portion 32 located closest to the Y− side via a through hole 35.

[0027] For example, a lead wire for external connection is joined to the electrode 50. A metal layer with low resistance such as copper, or a metal layer with good solderability such as gold may be laminated on the upper surface of the electrode 50. Although the resistor 30 and the electrode 50 are given different reference numerals for convenience, they can be integrally formed from the same material in the same process. Connection portions, which are wiring of a predetermined pattern that connect both ends of the resistor 30 and each electrode 50, may be provided between the two ends.

[0028] [Details of Resistor 30] The resistor 30 includes a first resistor portion 31 formed on the upper surface 10a of the substrate 10, which is an insulating layer, a second resistor portion 32 formed on the lower surface 10b of the substrate 10, and a through-hole 35 that penetrates the substrate 10 and electrically connects the first resistor portion 31 and the second resistor portion 32. In other words, the first resistor portion 31 and the second resistor portion 32 are electrically connected via the through-hole 35. The first resistor portion 31 and the second resistor portion 32 are connected by the through-hole 35 to form the resistor 30 that connects between a pair of electrodes 50.

[0029] The first resistor section 31 includes a plurality of elongated first portions 311 and resistance-adjusting patterns 312 that bridge adjacent first portions 311. The resistance-adjusting patterns 312 are resistance adjusting portions used to adjust the resistance value of the resistor 30. The first portions 311 are arranged side by side at predetermined intervals with their longitudinal directions directed in the X direction. Each resistance-adjusting pattern 312 only needs to bridge adjacent first portions 311, and does not need to be perpendicular to the first portions 311.

[0030] The longitudinal direction of each first resistor portion 31 is the grid direction, and the direction perpendicular to the grid direction is the grid width direction. That is, in the example of Fig. 1, the X direction is the grid direction, and the Y direction perpendicular to the X direction is the grid width direction.

[0031] In the strain gauge 1, the first resistance section 31 includes a plurality of electrically independent blocks spaced apart from one another, and the second resistance section 32 includes a plurality of electrically independent blocks spaced apart from one another. Adjacent blocks of the first resistance section 31 are connected in series by blocks that make up the second resistance section 32. This will be explained in detail below.

[0032] In the example of FIG. 1, the first resistor section 31 can be divided into four blocks A1 to A4 spaced apart in the Y direction. Block A1 is provided with two adjacent first portions 311 and five resistance-adjusting patterns 312 bridging the first portions 311. Blocks A2, A3, and A4 have the same configuration as block A1. The four blocks are not electrically connected on the upper surface 10a side of the substrate 10. In this way, a plurality of resistance-adjusting patterns 312 can be provided to bridge the adjacent portions of first resistor sections 31 of the same block (i.e., two adjacent first portions 311) to provide electrical continuity.

[0033] The number, shape, and other configurations of the blocks shown in FIG. 1 are not limited to the example shown in FIG. 1 . Furthermore, the blocks do not need to have the same configuration. For example, at least one block constituting the first resistor section 31 may include multiple resistance-adjustment patterns 312 that bridge adjacent first portions 311 of the first resistor section 31. In other words, not all blocks need to include the resistance-adjustment patterns 312. Alternatively, as shown in FIG. 1 , multiple resistance-adjustment patterns 312 may be provided in each block constituting the first resistor section 31. In either case, cutting the resistance-adjustment patterns 312 enables adjustment to increase the resistance value of the resistor 30. However, at least one resistance-adjustment pattern 312 must be left uncut in each block. The remaining resistance-adjustment pattern 312 functions as a folding pattern that folds back adjacent first portions 311.

[0034] The second resistor section 32 includes a plurality of elongated second portions 321 and a plurality of folded patterns 323. The second portions 321 are arranged side by side in the Y direction at predetermined intervals, with their longitudinal direction oriented in the X direction. Each folded pattern 323 connects the X+ side ends of adjacent second portions 321, except for the second portions 321 located closest to the Y+ side and the Y- side. The folded patterns 323 need only connect the X+ side ends of adjacent second portions 321, and do not need to be perpendicular to the second portions 321.

[0035] In the example of FIG. 3, the second resistor section 32 can be divided into five blocks B1 to B5 spaced apart in the Y direction. Only one second portion 321 is arranged in each of blocks B1 and B5. Block B2 is provided with two adjacent second portions 321 and a folded pattern 323 that connects their X+ side ends. In block B2, the two second portions 321 and the folded pattern 323 are connected in series. Blocks B3 and B4 have the same configuration as block B2. The five blocks are not electrically connected on the lower surface 10b side of the substrate 10.

[0036] The X-side end of the second portion 321 of the block B1 is connected to the X-side end of the Y+ side first portion 311 of the block A1 via the through-hole 35. In addition, the X-side end of the Y+ side second portion 321 of the block B2 is connected to the X-side end of the Y-side first portion 311 of the block A1 via the through-hole 35.

[0037] The X-side end of the second portion 321 on the Y-side of block B2 is connected to the X-side end of the first portion 311 on the Y+ side of block A2 via through-hole 35. In addition, the X-side end of the second portion 321 on the Y+ side of block B3 is connected to the X-side end of the first portion 311 on the Y-side of block A2 via through-hole 35.

[0038] The X-side end of the second portion 321 on the Y-side of block B3 is connected to the X-side end of the first portion 311 on the Y+ side of block A3 via through-hole 35. In addition, the X-side end of the second portion 321 on the Y+ side of block B4 is connected to the X-side end of the first portion 311 on the Y-side of block A3 via through-hole 35.

[0039] The X-side end of the second portion 321 on the Y-side of block B4 is connected to the X-side end of the first portion 311 on the Y+ side of block A4 via through-hole 35. In addition, the X-side end of the second portion 321 of block B5 is connected to the X-side end of the first portion 311 on the Y-side of block A4 via through-hole 35.

[0040] Furthermore, the X+ side end of the second portion 321 of block B1 is connected to the Y+ side electrode 50 via the through-hole 35, and the X+ side end of the second portion 321 of block B5 is connected to the other Y- side electrode 50 via the through-hole 35. With these connections, one resistor 30 is formed that connects between a pair of electrodes 50. Note that the number, shape, and other configurations of each block shown in FIG. 3 are not limited to the example of FIG. 3. Furthermore, each block does not have to have the same configuration.

[0041] A cover layer (insulating resin layer) may be provided on the upper surface 10a and / or the lower surface 10b of the substrate 10 of the strain gauge 1. The cover layer is provided on the upper surface 10a of the substrate 10 so as to cover the first resistive portion 31 of the resistor 30 and expose the electrode 50. The cover layer is provided on the lower surface 10b of the substrate 10 so as to cover the second resistive portion 32 of the resistor 30. Examples of materials for the cover layer include insulating resins such as PI resin, epoxy resin, PEEK resin, PEN resin, PET resin, PPS resin, and composite resins (e.g., silicone resin and polyolefin resin). The cover layer may contain a filler or a pigment. The thickness of the cover layer is not particularly limited and can be appropriately selected depending on the purpose. For example, the thickness of the cover layer can be approximately 2 μm to 30 μm. The provision of the cover layer can prevent mechanical damage to the resistor 30. The provision of the cover layer can also protect the resistor 30 from moisture and the like.

[0042] In this way, the strain gauge 1 has the resistance adjustment pattern 312 as a resistance adjustment section that bridges the adjacent first portions 311 of the first resistance section 31, and therefore can precisely adjust the resistance value of the resistor 30. For example, in a configuration in which all blocks that make up the first resistance section 31 include multiple resistance adjustment patterns 312, the resistance value of the resistor 30 can be finely adjusted.

[0043] Furthermore, by connecting the first resistive portion 31 and the second resistive portion 32 in series via the through-hole 35, it is possible to increase the length of the resistor 30 without increasing the area of ​​the upper surface 10a and the lower surface 10b of the substrate 10. As a result, the strain gauge 1 according to this embodiment can increase the resistance value of the resistor 30 compared to conventional strain gauges having substrates of the same size. In other words, according to this embodiment, the resistance value of the resistor 30 can be increased while suppressing an increase in the area of ​​the substrate 10 of the strain gauge 1. Furthermore, increasing the resistance value of the resistor 30 widens the range of options for the resistance value of the resistor 30 during the design stage of the strain gauge 1. Therefore, according to this embodiment, a strain gauge with a high degree of freedom in designing the resistance value during the manufacturing stage can be realized.

[0044] The strain gauge 1 according to this embodiment may have three or more layers of resistive sections formed via a substrate and an insulating layer. The resistive sections may be connected by through-holes. For example, an insulating layer covering the second resistive sections 32 may be provided on the lower surface 10b of the substrate 10. For example, in blocks B2 to B4, the folded patterns 323 connecting adjacent second sections 321 are not provided on the lower surface 10b of the substrate 10, but are provided on the lower surface of an insulating layer provided on the lower surface 10b of the substrate 10 by forming through-holes in the insulating layer. In this case, the resistance value of the resistor can be increased by increasing the length of the folded patterns 323 provided on the lower surface of the insulating layer.

[0045] In the above description, an example has been shown in which the first resistor portion 31 and the second resistor portion 32 are provided on both sides of the substrate 10, which is an insulating layer, but the present invention is not limited to this. For example, an insulating layer separate from the substrate 10 may be provided on the substrate 10, the first resistor portion 31 may be formed on one side of the insulating layer, and the second resistor portion 32 may be formed on the other side, and through-holes 35 may be provided that penetrate the insulating layer and electrically connect the first resistor portion 31 and the second resistor portion 32. In this case, the same effect as above can be obtained by providing a resistance-adjusting pattern 312 that bridges the adjacent first portions 311 of the first resistor portion 31 as a resistance-adjusting portion.

[0046] [Strain gauge manufacturing method] The following describes a method for manufacturing the strain gauge 1. To manufacture the strain gauge 1, first, a substrate 10 is prepared, and a metal layer (for convenience, referred to as metal layer A) is formed on the upper surface 10a of the substrate 10. Metal layer A is a layer that will ultimately be patterned to become the first resistor portion 31 and electrode 50. Therefore, the material and thickness of metal layer A are the same as those of the first resistor portion 31 and electrode 50 described above.

[0047] Next, through holes are formed in the substrate 10, penetrating the substrate 10 and reaching the surface of the metal layer A. The through holes can be formed by, for example, laser processing or drilling. Next, a metal layer (for convenience, referred to as metal layer B) is formed on the lower surface 10b of the substrate 10. Metal layer B is a layer that will ultimately be patterned to become the second resistor portion 32. Therefore, the material and thickness of metal layer B are the same as those of the second resistor portion 32 described above. Metal layer B is also formed in the through holes to become through holes 35 that are electrically connected to metal layer A.

[0048] The through-holes 35 may be provided after forming the metal layers A and B. For example, after forming the metal layers A and B, through-holes are provided that penetrate the metal layer A and the substrate 10 and reach the surface of the metal layer B. Then, the through-holes 35 can be formed by filling the through-holes with a conductor such as a conductive paste.

[0049] Note that a base layer may be formed on the upper surface 10a of the substrate 10 before forming the metal layer A. Alternatively, a base layer may be formed on the lower surface 10b of the substrate 10 before forming the metal layer B. For example, a functional layer having a predetermined film thickness may be formed as a base layer on each of the upper surface 10a and the lower surface 10b of the substrate 10. The film formation method is not particularly limited, but the functional layer can be vacuum-formed on the upper surface 10a and / or the lower surface 10b of the substrate 10 by, for example, conventional sputtering.

[0050] In the present application, the functional layer refers to a layer having the function of promoting the crystal growth of at least the upper layers, namely, metal layers A and B (resistor 30). The functional layer preferably also has the function of preventing oxidation of metal layer A due to oxygen or moisture contained in the substrate 10, and / or the function of improving adhesion between the substrate 10 and metal layers A and B. The functional layer may also have other functions.

[0051] The insulating resin film constituting the substrate 10 may contain oxygen and moisture, and Cr may form a self-oxidized film. Therefore, particularly when the metal layers A and B contain Cr, it is preferable to form a functional layer having the function of preventing oxidation of the metal layer A.

[0052] In this way, by providing a functional layer below the metal layers A and B, it is possible to promote the crystal growth of the metal layers A and B, and to produce metal layers A and B consisting of a stable crystalline phase. As a result, the stability of the gauge characteristics of the strain gauge 1 is improved. Furthermore, the material that constitutes the functional layer diffuses into the metal layers A and B, thereby improving the gauge characteristics of the strain gauge 1.

[0053] 4 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. Fig. 4 shows the cross-sectional shape of the strain gauge 1 when a functional layer 20a is provided as an underlying layer for the first resistor 31 and the electrode 50, and a functional layer 20b is provided as an underlying layer for the second resistor 32.

[0054] The planar shape of the functional layer 20a may be patterned to be substantially the same as the planar shape of the first resistor portion 31, for example. The planar shape of the functional layer 20b may be patterned to be substantially the same as the planar shape of the second resistor portion 32, for example. However, the planar shapes of the functional layer 20a and the first resistor portion 31, and the planar shapes of the functional layer 20b and the second resistor portion 32 do not have to be substantially the same. For example, if the functional layer 20a is formed from an insulating material, the functional layer 20a may be patterned to be different from the planar shape of the first resistor portion 31. In this case, the functional layer 20a may be formed in a solid shape in the region where the first resistor portion 31 is formed, for example. Alternatively, the functional layer 20a may be formed in a solid shape over the entire upper surface 10a of the substrate 10. The same applies to the relationship between the functional layer 20b and the second resistor portion 32. Note that only one of the functional layers 20a and 20b may be provided.

[0055] Next, the metal layer A is patterned by photolithography to form the first resistor portion 31 and the two electrodes 50 having the planar shape shown in Fig. 1. Furthermore, the metal layer B is patterned by photolithography to form the second resistor portion 32 having the planar shape shown in Fig. 3.

[0056] After forming the first resistor portion 31, the second resistor portion 32, and the through-hole 35, the resistance value of the resistor 30 between the electrodes 50 is measured, and if necessary, one or more resistance adjustment patterns 312 are cut using a laser or the like to adjust the resistance value of the resistor 30 to the desired value.

[0057] After the resistance value of the resistor 30 has been adjusted, a cover layer may be formed on the upper surface 10a of the substrate 10. The cover layer covers the first resistor portion 31, but the electrode 50 may be exposed from the cover layer. For example, the cover layer can be formed by laminating a semi-cured thermosetting insulating resin film on the upper surface 10a of the substrate 10 so as to cover the first resistor portion 31 and expose the electrode 50, and then heating and curing the insulating resin film. Alternatively, a cover layer that covers the second resistor portion 32 may be formed on the lower surface 10b of the substrate 10. The strain gauge 1 is completed through the above steps.

[0058] <Modification 1 of the First Embodiment> In Modification 1 of the first embodiment, an example is shown in which the position and shape of the resistance adjuster are different from those of Embodiment 1. Note that in Modification 1 of the first embodiment, descriptions of components that are the same as those in the embodiments already described may be omitted.

[0059] FIG. 5 is a plan view illustrating a strain gauge according to Modification 1 of the first embodiment. The strain gauge 1A shown in FIG. 5 is a strain gauge after resistance adjustment. Referring to FIG. 5, the strain gauge 1A differs from the strain gauge 1 shown in FIG. 1 in that the first resistor portion 31 is replaced with a first resistor portion 31A and that a resistance-adjustment through-hole 36 is provided. In the strain gauge 1A, the pattern of the second resistor portion 32 is the same as that shown in FIG. 3. The resistance-adjustment through-hole 36 is a through-hole that is opened for resistance adjustment after the formation of the first resistor portion 31A and the second resistor portion 32. This modification differs from the strain gauge 1 shown in FIG. 1 in that the resistance-adjustment through-hole 36 is provided while adjusting its position after the formation of the first resistor portion 31A and the second resistor portion 32.

[0060] In the strain gauge 1A after resistance adjustment shown in Fig. 5, the first resistor portion 31A includes a plurality of electrically independent blocks spaced apart from one another, and the second resistor portion 32 includes a plurality of electrically independent blocks spaced apart from one another. Adjacent blocks of the first resistor portion 31A are connected in series by resistance-adjustment through-holes 36 and blocks of the second resistor portion 32 connected via the resistance-adjustment through-holes 36. The folded patterns 323 of the blocks of the second resistor portion 32 connected via the resistance-adjustment through-holes 36 are connected in parallel to the resistance-adjustment through-holes 36. This will be explained in detail below.

[0061] In the strain gauge 1A, each of the blocks A1 to A4 of the first resistance section 31A is provided with a folded pattern 313 that connects two adjacent first portions 311 and their X+ side ends. Also, a resistance adjustment through hole 36 is provided as a resistance adjustment section to bridge the opposing first portions 311 that belong to adjacent blocks.

[0062] In the strain gauge 1 shown in FIG. 1, the resistance adjustment pattern 312 connects the first portions 311 belonging to each block so as to bridge them together. In contrast, the resistance adjustment through hole 36 of the strain gauge 1A shown in FIG. 5 connects a certain first portion 311 to a first portion 311 adjacent to that first portion 311, but belonging to a different block (i.e., an adjacent block), so as to bridge it together. The resistance adjustment through hole 36 also penetrates the substrate 10 and reaches the lower surface 10b of the substrate 10. Therefore, when the resistance adjustment through hole 36 is formed at a certain location so as to bridge the first portions 311, the resistance adjustment through hole 36 appears on the lower surface 10b at a location exactly opposite the certain location across the substrate 10. In this embodiment, the first portion 311 of the first resistor 31A and the second portion 321 of the second resistor 32 overlap in a plan view, so the resistance-adjusting through-holes 36 formed on the lower surface 10b bridge and connect adjacent second portions 321 on the lower surface 10b as well. In the example of FIG. 5, the second portions 321 have the same shape as in FIG. 3, so the second portions 321 within the same block bridge each other. The resistance-adjusting through-holes 36 also connect the first portion 311 and the second portion 321.

[0063] In this manner, at least one of the through holes electrically connecting the first resistor portion 31A and the second resistor portion 32 may be a resistance-adjustment through hole 36. The resistance-adjustment through hole 36 is provided so that the formation of the resistance-adjustment through hole 36 provides electrical continuity between adjacent first resistor portions 31A and also provides electrical continuity between adjacent second resistor portions 32. For example, the resistance-adjustment through hole 36 is provided so that the formation of the resistance-adjustment through hole 36 provides electrical continuity between adjacent first resistor portions 31A in different blocks and also provides electrical continuity between adjacent second resistor portions 32. Note that in the example of FIG. 5 , the resistance-adjustment through hole 36 provides electrical continuity between second resistor portions 32 belonging to the same block, but the resistance-adjustment through hole 36 may bridge and provide electrical continuity between second resistor portions 32 belonging to different blocks.

[0064] Furthermore, while the resistance adjustment pattern 312 of the strain gauge 1 shown in FIG. 1 is a planar conductor pattern formed on the upper surface 10a of the substrate 10, the resistance adjustment through hole 36 of the strain gauge 1A shown in FIG. 5 bridges the first portion 311 as described above and penetrates the substrate 10.

[0065] In the strain gauge 1 shown in FIG. 1, all of the blocks A1 to A4 of the first resistor portion 31 are connected to one of the blocks B1 to B5 of the second resistor portion 32 via through-holes 35. In contrast, in the strain gauge 1A shown in FIG. 5, the X-side end of the second portion 321 of block B1 is connected to the X-side end of the first portion 311 on the Y+ side of block A1 via through-holes 35. The X-side end of the second portion 321 of block B5 is connected to the X-side end of the first portion 311 on the Y- side of block A4 via through-holes 35. While FIG. 5 shows the strain gauge 1A after resistance adjustment, the strain gauge 1A before resistance adjustment does not have the resistance adjustment through-hole 36 shown in FIG. 5. The first resistor portion 31A and the second resistor portion 32 of the strain gauge 1A before resistance adjustment are not connected at any point other than the two through-holes 35.

[0066] In other words, in the state where the resistance-adjusting through-hole 36 is not provided, the first resistance portion 31A and the second resistance portion 32 do not form one resistor 30 connecting between a pair of electrodes 50.

[0067] In other words, if the resistance-adjusting through-holes 36 are provided in the first resistor portion 31A, the resistance-adjusting through-holes 36 will penetrate the substrate 10 and connect the first resistor portion 31A and the second resistor portion 32. As a result, the first resistor portion 31A and the second resistor portion 32 can form one resistor element 30 that connects between a pair of electrodes 50. Furthermore, when providing the resistance-adjusting through-holes 36 in this manner, the resistance value of the resistor element 30 can be adjusted by changing the position of each resistance-adjusting through-hole 36 in the X direction.

[0068] Because the resistance-adjustment through-holes 36 have a higher resistance value than the folded pattern 323 of the second resistor section 32, current flows mainly along the route indicated by the arrow in FIG. 6. Note that, instead of providing resistance-adjustment through-holes 36 bridging adjacent first portions 311, the same current route as in FIG. 6 can be achieved by providing through-holes in each adjacent first portion 311 that connect the first portion 311 to the second portion 321 that overlaps the first portion 311 in plan view. However, in this case, two through-holes must be formed. By providing resistance-adjustment through-holes 36 bridging adjacent first portions 311, the process of forming the through-holes can be simplified.

[0069] The resistance adjustment through-holes 36 can be provided at positions calculated in advance during the design stage of the strain gauge 1A. Alternatively, the resistance adjustment through-holes 36 can be provided at positions determined while checking the resistance value during the manufacturing process of the strain gauge 1A. Alternatively, these positioning methods can be used in combination. In this way, by forming the resistance adjustment through-holes 36 at positions determined in advance and / or during the manufacturing process, a strain gauge 1A having a desired resistance value can be obtained. Specifically, the resistance value of the resistor 30 can be adjusted to decrease by changing the position of the resistance adjustment through-holes 36 in the X direction.

[0070] Furthermore, in the strain gauge 1A, in addition to the resistance adjustment through holes 36 that bridge the first portions 311 that belong to adjacent blocks, further resistance adjustment through holes 36 may be provided to bridge the first portions 311 that belong to the same block. This allows for more precise resistance adjustment.

[0071] The resistance-adjusting through-holes 36 can be formed by irradiating the strain gauge 1A with laser light. By adjusting the irradiation intensity and irradiation time of the laser light to form through-holes of a predetermined diameter in the substrate 10, the metal constituting the first portions 311 adjacent to the through-holes is melted by the heat of the laser light, and the inner walls of the through-holes are coated with the molten metal. In this manner, the resistance-adjusting through-holes 36 are formed. The resistance-adjusting through-holes 36 can provide electrical continuity between adjacent first portions 311.

[0072] Another method for forming the resistance-adjusting through-holes 36 is as follows. That is, a through-hole having a diameter sufficient to reach from a certain first portion 311 to a first portion 311 adjacent to the certain first portion 311 may be formed in the substrate 10. In this case, the irradiation intensity and irradiation time of the laser light do not need to be sufficient to melt the metal constituting the first portions 311. In this case, the through-holes can be filled with a metal paste or the like to establish electrical continuity between the adjacent first portions 311. In this case, a mechanical method such as drilling may be used to form the through-holes instead of irradiating the laser light.

[0073] The first embodiment and the first modification of the first embodiment can be combined. For example, the strain gauge 1 shown in Fig. 1 may further be provided with a resistance-adjustment through-hole 36. Alternatively, the strain gauge 1A shown in Fig. 5 may be provided with a resistance-adjustment pattern 312. In other words, the strain gauge may include both the resistance-adjustment pattern 312 and the resistance-adjustment through-hole 36 as a resistance adjustment portion.

[0074] In this way, by providing both the resistance-adjustment pattern 312 and the resistance-adjustment through-holes 36, the resistance value of the resistor 30 can be increased by cutting the resistance-adjustment pattern 312, and the resistance value of the resistor 30 can be decreased by forming the resistance-adjustment through-holes 36. In other words, it is possible to both increase and decrease the resistance value of the resistor 30. In other words, by providing both the resistance-adjustment pattern 312 and the resistance-adjustment through-holes 36, the resistance value of the resistor 30 can be increased or decreased as desired, and therefore the adjustment range of the resistance value of the resistor 30 can be wider than when only one of them is provided. Therefore, a strain gauge capable of detecting strain with higher accuracy can be realized.

[0075] <Modification 2 of the First Embodiment> In the second modification of the first embodiment, an example is shown in which a part or all of the second resistor portion is a resistance-adjusting pattern. Note that in the second modification of the first embodiment, the description of the same components as those in the already described embodiments may be omitted.

[0076] Fig. 7 is a plan view (part 1) illustrating a strain gauge according to Modification 2 of the first embodiment. Fig. 8 is a plan view (part 2) illustrating a strain gauge according to Modification 2 of the first embodiment, in which the first resistor portion and electrodes have been removed from Fig. 7 for convenience in order to show the pattern of the second resistor portion.

[0077] Referring to Figures 7 and 8, strain gauge 1B differs from strain gauge 1 shown in Figure 1 in that first resistance portion 31 and second resistance portion 32 are replaced with first resistance portion 31B and second resistance portion 32B.

[0078] In the strain gauge 1B, the first resistor portion 31B is a single continuous pattern. The second resistor portion 32B is also a single continuous pattern that is different from the pattern of the first resistor portion 31B. In the strain gauge 1B, the first resistor portion 31B and the second resistor portion 32B are connected by a through-hole 35, and part or all of the second resistor portion 32B serves as a resistance adjustment portion. This will be explained in detail below.

[0079] In the strain gauge 1B, the first resistance portion 31B includes a plurality of elongated first portions 311B and a folded pattern 313B that alternately connects the ends of the first portions 311B. The first portions 311B are arranged in parallel with each other at a predetermined interval along the longitudinal direction of the X-axis. The plurality of first portions 311B may include first portions 311B with different lengths in the X-axis. The interval between adjacent first portions 311B may not be constant. The second resistance portion 32B includes a plurality of elongated second portions 321B and a folded pattern 323B that alternately connects the ends of the second portions 321B. The second portions 321B are arranged in parallel with each other at a predetermined interval along the longitudinal direction of the X-axis. The plurality of second portions 321B may include second portions 321B with different lengths in the X-axis. The interval between adjacent second portions 321B may not be constant.

[0080] In the strain gauge 1B, before the through-holes 35 are provided, the first resistance portion 31B and the second resistance portion 32B each have a single continuous pattern and are not electrically connected to each other. The first resistance portion 31B and the second resistance portion 32B have a partially intersecting region and / or a partially overlapping region in a plan view.

[0081] In the strain gauge 1B, two or more through holes 35 are provided at any position in the region where the first resistance portion 31B and the second resistance portion 32B partially intersect and / or partially overlap in a plan view, so that the first resistance portion 31B and the second resistance portion 32B can be electrically connected via the through holes 35. The second resistance portion 32B connected to the first resistance portion 31B by the through holes 35 bridges the first portion 311B of the first resistance portion 31B.

[0082] In this way, in the strain gauge 1B, the resistance value of the resistor 30 can be adjusted by the position and number of through holes 35 provided in the region where the first resistive portion 31B and the second resistive portion 32B partially intersect and / or partially overlap in a plan view. That is, in the strain gauge 1B, part or all of the second resistive portion 32B functions as a resistance adjustment pattern.

[0083] The through-holes 35 can be provided at positions that are calculated in advance during the design stage of the strain gauge 1B. Alternatively, the through-holes 35 can be provided at positions that are determined while checking the resistance value during the manufacturing process of the strain gauge 1B. Alternatively, these positioning methods can be used in combination.

[0084] It is possible to combine the second modification of the first embodiment with the first embodiment and / or the first modification of the first embodiment. For example, in Fig. 7, the resistance-adjustment patterns 312 may be provided so as to bridge the adjacent first portions 311B. Alternatively, in Fig. 7, the resistance-adjustment through-holes 36 may be provided so as to bridge the adjacent first portions 311B. Alternatively, both of these may be provided.

[0085] <Modification 3 of the First Embodiment> In the third modification of the first embodiment, an example is shown in which the first resistor portion and the second resistor portion have a spiral pattern. Note that in the third modification of the first embodiment, the description of the same components as those in the previously described embodiments may be omitted.

[0086] Fig. 9 is a plan view (part 1) illustrating a strain gauge according to Modification 3 of the first embodiment. Fig. 10 is a plan view (part 2) illustrating a strain gauge according to Modification 3 of the first embodiment, in which the first resistor and electrodes have been removed from Fig. 9 for convenience in order to show the pattern of the second resistor.

[0087] Referring to Figures 9 and 10, strain gauge 1C differs from strain gauge 1 shown in Figure 1 in that first resistance portion 31 and second resistance portion 32 are replaced with first resistance portion 31C and second resistance portion 32C.

[0088] As shown in Fig. 9, in the strain gauge 1C, the first resistor portion 31C is patterned in a spiral shape in a plan view. The first resistor portion 31C is a single continuous pattern that connects a pair of electrodes 50. For convenience, the portion from one electrode 50 to the folded pattern 313C is referred to as a first portion 311C, and the portion from the folded pattern 313C to the other electrode 50 is referred to as a second portion 312C. Note that in Fig. 9, the first portion 311C, the second portion 312C, and the folded pattern 313C are shown with different matte finishes for convenience.

[0089] The first portion 311C extends from one electrode 50 and is patterned in a spiral shape in a clockwise direction from the outer periphery to the center, reaching the folded pattern 313C. The second portion 312C extends from the folded pattern 313C and is patterned in a spiral shape in a counterclockwise direction from the center to the outer periphery, reaching the other electrode 50.

[0090] In principle, the first portions 311C and the second portions 312C are arranged alternately. That is, except for a portion near the folded pattern 313C, the first portion 311C is always adjacent to the second portion 312C, and the second portion 312C is always adjacent to the first portion 311C. Except for a portion near the folded pattern 313C, the first portions 311C and the second portions 312C are never adjacent to each other.

[0091] 10, in the strain gauge 1C, the second resistor portion 32C has the same pattern as the first resistor portion 31C and is formed at a position overlapping the first resistor portion 31C in a plan view. The second resistor portion 32C includes a third portion 321C, a fourth portion 322C, and a folded pattern 323C. The second resistor portion 32C is electrically connected to the first resistor portion 31C via through holes 35 near both ends.

[0092] FIG. 11 is a diagram illustrating the adjustment of the resistance value of a strain gauge 1C. As shown in FIG. 11, one or more resistance adjusters 314C can be provided to bridge the adjacent first portion 311C and second portion 312C. The position and number of resistance adjusters 314C can be set as desired, taking into account the required resistance adjustment range. In FIG. 11, as an example, eleven resistance adjusters 314C are provided, and for convenience, the eleven resistance adjusters 314C are numbered 1 to 11, starting from the side closest to the folded pattern 313C.

[0093] The resistance adjustment portion 314C is, for example, a resistance adjustment through-hole that penetrates the substrate 10. The resistance adjustment portion 314C is formed to a size such that the conductor constituting the resistance adjustment through-hole reaches the adjacent first portion 311C and second portion 312C. This establishes electrical continuity between the adjacent first portion 311C and second portion 312C, as well as between the third portion 321C and fourth portion 322C that overlap in a plan view. This allows the resistance value of the resistor 30 to be adjusted downward.

[0094] The resistance-adjusting portion 314C may be a planar resistance-adjusting pattern formed in advance on the upper surface 10a of the substrate 10 so as to electrically connect the adjacent first portion 311C and second portion 312C. In this case, by cutting any resistance-adjusting pattern with a laser or the like, it is possible to adjust the resistance value of the resistor 30 in a direction to increase it.

[0095] Of course, both a resistance-adjustment through-hole and a resistance-adjustment pattern may be provided as the resistance-adjustment portion 314C. With this configuration, the resistance value of the resistor 30 can be increased by cutting the resistance-adjustment pattern. Also, the resistance value of the resistor 30 can be decreased by forming a resistance-adjustment through-hole. Since the resistance value of the resistor 30 can be increased or decreased as desired, the degree of freedom in resistance adjustment is improved. Therefore, a strain gauge capable of highly accurate strain detection can be realized.

[0096] The resistance adjusting portion 314C can be provided at a position calculated in advance during design. If the resistance adjusting portion 314C is a resistance adjusting through hole, the resistance adjusting portion 314C may be provided at a position determined while checking the resistance value during the manufacturing process of the strain gauge 1C. Alternatively, both methods may be used in combination.

[0097] A spiral pattern such as the first resistor portion 31C or the second resistor portion 32C is effective for a measurement object in which tensile and compressive strain distribution occurs concentrically from the center. In other words, by forming the first resistor portion 31C or the second resistor portion 32C into a spiral pattern, strain can be detected around the entire circumference of the concentric circle, and minute strain can be detected efficiently.

[0098] The first resistor portion 31C and the second resistor portion 32C are not limited to a rectangular spiral shape and may be a circular spiral shape. Alternatively, they may be spiral shapes other than rectangular or circular. In these cases, the same effects as those described above can be achieved.

[0099] The preferred embodiments have been described above in detail. However, the strain gauge according to the present disclosure is not limited to the above-described embodiments and modifications. For example, various modifications and substitutions can be made to the strain gauge according to the above-described embodiments without departing from the scope of the claims. [Explanation of symbols]

[0100] 1, 1A, 1B, 1C strain gauge, 10 substrate, 10a upper surface, 10b lower surface, 20a, 20b functional layer, 30 resistor, 31, 31A, 31B, 31C first resistor portion, 32, 32B, 32C second resistor portion, 35 through hole, 36 resistance adjustment through hole, 50 electrode, 311, 311B, 311C first portion, 312 resistance adjustment pattern, 312C, 321, 321B second portion, 313, 313B, 313C, 323, 323B, 323C folded pattern, 314C resistance adjustment portion, 321C third portion, 322C fourth portion

Claims

1. an insulating layer and a resistor, The resistor is a first resistor portion formed on one surface of the insulating layer; a second resistor portion formed on the other surface of the insulating layer; a through hole that penetrates the insulating layer and electrically connects the first resistor portion and the second resistor portion, the first resistor portion and the second resistor portion are connected via the through hole to form the resistor body connecting a pair of electrodes; a resistance adjusting portion including a resistance adjusting pattern formed on one surface of the insulating layer is provided; the first resistor portion includes a plurality of elongated first portions; The first portions are arranged side by side at predetermined intervals with their longitudinal directions facing the same direction, the first resistor portion includes a plurality of electrically independent blocks spaced apart from one another; At least one of the plurality of blocks includes a plurality of the first portions; The resistance-adjusting pattern is provided in at least one of the blocks so as to bridge adjacent first portions among the plurality of first portions to provide electrical continuity.

2. A strain gauge as described in Claim 1, wherein multiple resistance adjustment patterns are provided.

3. 3. The strain gauge according to claim 1, wherein a plurality of the resistance adjustment patterns are provided on each block constituting the first resistance portion.

4. the first resistor portion includes a plurality of electrically independent blocks spaced apart from one another; the second resistor section includes a plurality of electrically independent blocks spaced apart from one another; 4. The strain gauge according to claim 1, wherein adjacent blocks constituting the first resistor section are connected in series by blocks constituting the second resistor section.

5. The second resistance portion includes a plurality of elongated second portions, The second portions are arranged side by side at predetermined intervals with their longitudinal directions facing the same direction, At least one of the through holes is a resistance adjustment through hole, 5. The strain gauge according to claim 1, wherein the resistance-adjusting through-hole is configured to electrically connect adjacent ones of the plurality of first portions and to electrically connect adjacent ones of the plurality of second portions.

6. the first resistor portion includes a plurality of electrically independent blocks spaced apart from one another; the second resistor section includes a plurality of electrically independent blocks spaced apart from one another; 6. The strain gauge according to claim 5, wherein the resistance-adjusting through-hole is provided so as to electrically connect adjacent portions of the first resistance portions of different blocks.

7. the first resistor portion includes a plurality of electrically independent blocks spaced apart from one another; the second resistor section includes a plurality of electrically independent blocks spaced apart from one another; 7. The strain gauge according to claim 5, wherein adjacent blocks constituting the first resistance portion are connected in series by the resistance adjustment through-holes and the blocks constituting the second resistance portion connected via the resistance adjustment through-holes.

8. A semiconductor device comprising an insulating layer and a resistor, The resistor is a first resistor portion formed on one surface of the insulating layer; a second resistor portion formed on the other surface of the insulating layer; a through hole that penetrates the insulating layer and electrically connects the first resistor portion and the second resistor portion, the first resistor portion and the second resistor portion are connected via the through hole to form the resistor body connecting a pair of electrodes; A resistance adjusting unit is provided, the first resistor portion includes a plurality of elongated first portions; The first portions are arranged side by side at predetermined intervals with their longitudinal directions facing the same direction, the first resistor portion is a continuous pattern including a plurality of the first portions, the second resistor portion is a single continuous pattern that is different from the pattern of the first resistor portion, A strain gauge in which two or more of the plurality of first portions are connected to the second resistance portion by the through hole, and part or all of the second resistance portion serves as the resistance adjustment portion.

9. The resistor is made of Cr, CrN, and Cr ２ The strain gauge according to claim 1 , which is formed from a film containing N.

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