Sensor

Abstract

To provide a sensor which can suitably secure the insulation property between a conductive film pattern and a surface of a metal base when the metal base having the surface formed with streaks is used.SOLUTION: A sensor includes a metal base having a surface formed with streaks along a first direction in plan view, and a conductive film pattern formed on the surface via an insulation film. On the surface, the insulation film covers a first area which exists in the first direction in plan view from a conductive film pattern forming area formed with the conductive film pattern, and the surface comprises an exposed area exposed from the insulation film at a position different from the first area in plan view.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a sensor in which a conductive film pattern is formed on a metal substrate via an insulating film. [Background technology]

[0002] Known sensors, such as pressure sensors, have a circuit formed on the surface of a metal substrate using a conductive film pattern. For example, one circuit uses the piezoresistive effect to detect strain in the substrate (also called a membrane or diaphragm) through resistance changes. Conventional sensors using metal substrates may have an exposed portion on the surface of the metal substrate that is exposed from the insulating film to ensure a contact position for a resistance welding electrode (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-43016 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional pressure sensors and strain sensors have used metal substrates with mirror-polished surfaces, but the inventors have developed a technology for using metal substrates with streaks formed on the surface as the metal substrate for pressure sensors and strain sensors, with the aim of reducing costs and improving production efficiency. The inventors have discovered that when providing an exposed portion on the surface of a metal substrate that is exposed from an insulating film as in the conventional case, using a metal substrate with streaks formed on the surface causes a problem in which insulation between the conductive film pattern and the surface of the metal substrate cannot be ensured.

[0005] The technology disclosed herein provides a sensor that can suitably ensure insulation between a conductive film pattern and the surface of a metal substrate when a metal substrate having a surface with striations formed thereon is used. [Means for solving the problem]

[0006] In order to achieve the above object, the sensor according to the present disclosure comprises: a metal substrate having a surface on which striations are formed along a first direction in a plan view; a conductive film pattern formed on the surface via an insulating film, a first region on the surface, which is located in the first direction in a plan view from a conductive film pattern formation region in which the conductive film pattern is formed, is covered with the insulating film; The surface has an exposed region exposed from the insulating film at a position different from the first region in a plan view.

[0007] The sensor according to the present disclosure uses a metal substrate having a surface with streaks, thereby reducing costs and improving production efficiency by eliminating the need for a mirror polishing process. Furthermore, because the first region is covered with an insulating film, even if etching residue of the conductive film along the streaks of the metal substrate occurs, insulation between the conductive film pattern and the surface of the metal substrate can be suitably ensured. Furthermore, by having an exposed region on the surface at a position different from the first region, it is possible to avoid short circuits between the conductive film pattern and the surface of the metal substrate due to etching residue of the conductive film, while allowing resistance welding electrodes to contact the surface.

[0008] Furthermore, for example, the surface may have at least two exposed regions sandwiching the conductive film pattern in a plan view.

[0009] Such a sensor can be efficiently fixed to another member by, for example, bringing resistance welding electrodes into contact with the two exposed areas.

[0010] Furthermore, for example, the conductive film pattern may have a pattern portion that is rectangular wave-shaped or meander-shaped in plan view, Two of the at least two exposed regions may sandwich the conductive film pattern in an amplitude direction of the rectangular wave shape or the meandering shape in a plan view.

[0011] A conductive film pattern having a pattern portion with a rectangular wave or meander shape in plan view can measure distortion in the amplitude direction of the rectangular wave or meander shape, but by configuring two exposed areas to sandwich the conductive film pattern in the amplitude direction in plan view, the direction connecting the fixing positions of the metal base material to another member can be aligned with the direction of the distortion to be detected by contacting the two exposed areas with resistance welding electrodes, etc. This allows distortion occurring in the other member to be efficiently transmitted to the metal base material, increasing the distortion detection sensitivity.

[0012] Furthermore, for example, the surface roughness Ra of the surface in a second direction perpendicular to the first direction in a plan view may be 0.05 μm or more and 1 μm or less.

[0013] When the surface roughness Ra is equal to or greater than a predetermined value, etching residue of the conductive film tends to occur along the first direction, so the above-described arrangement of the first region and exposed region is particularly effective. Furthermore, by setting the surface roughness Ra to a predetermined value or less, it is possible to form a thin conductive film pattern with high precision. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a plan view of a sensor according to a first embodiment of the present disclosure, showing the sensor in plan view. [Figure 2] FIG. 2 is a conceptual diagram illustrating the state of streaks formed on the surface of the substrate used in the sensor shown in FIG. [Figure 3] FIG. 3 is a conceptual diagram illustrating the state of streaks formed on the surface of the substrate shown in FIG. 2, and is a schematic cross-sectional view along the second direction near the surface of the substrate. [Figure 4] FIG. 4 is a conceptual diagram showing a process for fixing the sensor shown in FIG. 1 to another member when the sensor is used as a pressure sensor. [Figure 5] FIG. 5 is a plan view of the sensor according to the second embodiment, showing the sensor in plan view. [Figure 6] FIG. 6 is a plan view of the sensor according to the third embodiment, showing the sensor in plan view. [Figure 7] FIG. 7 is a plan view of the sensor according to the fourth embodiment, showing the sensor in plan view. [Figure 8] FIG. 8 is a conceptual diagram showing each region formed on the surface of the metal substrate used in the sensor shown in FIG. [Figure 9] FIG. 9 is a plan view of a sensor according to a reference example, showing the sensor in plan view. [Figure 10] FIG. 10 is a conceptual diagram showing an example of the occurrence of a short circuit between a conductive film pattern and the surface of a metal substrate, which may occur in the sensor according to the reference example. [Figure 11] FIG. 11 is a conceptual diagram showing another example of the occurrence of a short circuit between a conductive film pattern and the surface of a metal substrate, which may occur in the sensor according to the reference example. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, the present disclosure will be described based on embodiments shown in the drawings. Fig. 1 is a plan view of a sensor 10 according to a first embodiment of the present disclosure. The sensor 10 is attached to another member 70 as shown in Fig. 4 and used as a strain sensor or the like. Fig. 4 is a cross-sectional view showing an example in which the sensor 10 is used as a strain sensor that measures the strain of the other member 70.

[0016] 1 and 4, the sensor 10 has a metal substrate 20, an insulating film 30, and a conductive film pattern 40. The insulating film 30 and the conductive film pattern 40 are stacked on the surface 24 of the metal substrate 20 in this order: the insulating film 30, then the conductive film pattern 40.

[0017] The material of the metal substrate 20 is, for example, stainless steel, but is not particularly limited as long as it is a metallic material. Furthermore, when the measurement environment of the sensor 10 is a high-temperature condition, it is preferable to use austenitic SUS304 or 316 or precipitation hardened SUS630 or 631 for the metal substrate 20 because these materials have excellent high-temperature properties.

[0018] Fig. 2 is a conceptual diagram illustrating the state of streaks 25 formed on the surface 24 of the metal substrate 20 used in the sensor 10 shown in Fig. 1. As shown in Fig. 2, the metal substrate 20 has a surface 24 on which streaks are formed along a first direction D1 in a plan view. When the surface 24 of the metal substrate 20 is enlarged as shown in Fig. 2, streaks 25 made up of many fine streaks are formed over the entire surface 24.

[0019] FIG. 3 is a conceptual diagram illustrating the state of streaks 25 formed on the surface 24 of the metal substrate 20 shown in FIG. 2 , and is a schematic cross-sectional view along the second direction D2 near the surface 24 of the metal substrate 20. As shown in FIG. 3 , the streaks 25 are observed as undulations formed on the surface 24 in an enlarged cross-section, and can also be considered to be numerous linear flaws that are approximately parallel to the first direction D1 in a plan view. Examples of undulations that constitute such streaks 25 include grinding marks formed in the grinding direction during the production of the metal substrate 20 and rolling marks formed in the rolling direction during rolling, and these are formed intermittently or continuously across the entire surface 24. Note that if multiple types of streaks that are formed in different directions in a plan view are formed intermittently or continuously across the entire surface 24 (the surface of the substrate), the direction of the one type of streak that has the deeper unevenness is considered to be the first direction D1. For example, if grinding marks with a depth of 0.1 to 1.0 μm and polishing marks with a depth of 0.01 to 0.1 μm are formed on surface 24, the direction of the grinding marks with a depth of 0.1 to 1.0 μm is considered to be the first direction D1.

[0020] In the sensor 10, the surface roughness Ra of the surface 24 in the second direction D2, which is perpendicular to the first direction D1 in a plan view within the plane of the surface 24, is preferably 0.05 μm or more and 1 μm or less. When the surface roughness Ra of the surface 24 is a predetermined value or more, etching residue 51 of the conductive film is likely to occur along the first direction D1 (see FIG. 9 ), which is particularly effective in preventing the occurrence of a short circuit (short circuit defect) between the conductive film pattern 40 and the surface 24 of the metal base material 20 due to the etching residue 51. Furthermore, by setting the surface roughness Ra to a predetermined value or less, it is possible to form a thin conductive film pattern 40 with high precision.

[0021] The streaks 25 formed on the surface 24 can be eliminated by mirror-polishing the surface 24 before forming the insulating film 30 and the conductive film pattern 40 (see FIG. 4) on the surface 24, but mirror-polishing the surface 24 to eliminate the streaks 25 requires processing time and costs, resulting in a decrease in productivity. On the other hand, as in the metal substrate 20 shown in FIG. 2, by forming the insulating film 30 and the conductive film pattern 40 (see FIGS. 1 and 4) on the surface 24 while the streaks 25 are still formed, the productivity of the sensor 10 can be improved.

[0022] Furthermore, regarding the orientation of the sensor 10 and the metal base material 20, the normal direction of the surface 24, which is perpendicular to the first direction D1 and the second direction D2, will be described as the up-down direction. Furthermore, as shown in Fig. 4, within the up-down direction, the direction from the surface 24, on which the insulating film 30, the conductive film pattern 40, etc. are formed, to the back surface 22 of the metal base material 20, which is the opposite surface of the front surface 24, will be referred to as the down direction, and the direction from the back surface 22 to the front surface 24 will be referred to as the up direction.

[0023] 1 is formed on the surface 24 of the metal base material 20 via an insulating film 30. In the sensor 10, the insulating film 30 is formed to cover the surface 24 of the metal base material 20 except for exposed regions 27a and 27b formed at both ends in the second direction D2. The conductive film pattern 40 has electrode pads 44 and 45 and a resistive film 42 connecting the electrode pads 44 and 45.

[0024] The thickness of the insulating film 30 is not particularly limited, but can be, for example, 1 to 10 times the surface roughness Ra of the surface 24 shown in FIG. 3 . By making the thickness of the insulating film 30 a predetermined multiple or more of the surface roughness Ra of the surface 24, the insulation between the surface 24 of the metal base material 20 and the conductive film pattern 40 can be suitably ensured. Furthermore, if the thickness of the insulating film 30 is a predetermined multiple or less of the surface roughness Ra of the surface 24, undulations tracing the streaks 25 of the surface 24 are likely to form on the surface of the insulating film 30 facing the conductive film pattern 40, and etching residues 51 of the conductive film along the first direction D1 (see FIG. 9 ) are likely to occur. Therefore, it is particularly important and effective to avoid exposing the surface 24, such as the first-direction exposed region 826 in the sensor 810 according to the reference example shown in FIG. 9 , and to form the first region 26 and exposed regions 27a and 27b as shown in FIG. 1 to prevent short-circuit defects due to the etching residues 51. Details of the etching residues 51 will be described using the sensor 810 according to the reference example shown in FIG. 9 .

[0025] 1 and 4 may be made of silicon oxide, silicon nitride, alumina, or the like, but is not particularly limited as long as it is an insulating material. The method for forming the insulating film 30 is not particularly limited, but examples include sputtering, vacuum deposition, CVD, and the sol-gel method. Furthermore, the insulating film 30 can also be formed by a method that provides good coverage, such as the TEOS-CVD method. The sensor 10 according to the present disclosure can effectively prevent short-circuit defects in such cases.

[0026] 2 has electrode pads 44, 45 and a resistive film 42. The resistive film 42 of the conductive film pattern 40 connects a first position, which is the center position of the electrode pad 44, to a second position, which is the center position of the electrode pad 45, via a conductive path that is longer than the length of a straight line connecting the first position and the second position. By forming the conductive film pattern 40 in this shape, a long conductive path can be formed in a narrow area, and the detection sensitivity of the conductive film pattern 40 can be improved.

[0027] The resistive film 42 of the conductive film pattern 40 preferably has a meandering shape, in which the conductive path has a folded (or meandering) shape, allowing for the formation of a narrow and long conductive path in a narrow area. However, the planar shape of the resistive film 42 is not limited to a meandering shape, and may have other shapes that connect the first position and the second position in a detour relative to a straight line. The same applies to other embodiments.

[0028] 2, the conductive film pattern 40 has two electrode pads 44, 45 and a resistive film 42 that electrically connects the two electrode pads 44, 45. External wiring (not shown) is connected to the two electrode pads 44, 45 by wire bonding or the like. The resistive film 42 has a rectangular wave shape or a meandering shape with the first direction D1 as the amplitude direction, and forms a conductive path that is narrower than the electrode pads 44, 45, electrically connecting the two electrode pads 44, 45.

[0029] The conductive film pattern 40 is a pattern made of a conductive film and may be composed of a single film or multiple films, as long as it forms a conductive path connecting a first position and a second position. The electrode pads 44, 45 and the resistive film 42 of the conductive film pattern 40 shown in FIG. 1 may be made of the same material or different materials. Examples of materials for the resistive film 42 of the conductive film pattern 40 according to the embodiment include metals such as Cr, Ni, Al, and Cu, and strain-resistant film materials containing Cr, at least one of Ni, Al, and Cu, and at least one of N and O. Examples of materials for the electrode pads 44, 45 of the conductive film pattern 40 include good conductor metals such as Al and Au.

[0030] 1, on the surface 24 of the metal substrate 20, a first region 26 that exists in the first direction D1 in a plan view from a conductive film pattern formation region 46 where the conductive film pattern 40 is formed is covered with an insulating film 30. In FIG. 1, the conductive film pattern formation region 46 corresponds to the region where the electrode pads 44, 45 and the resistive film 42 that constitute the conductive film pattern 40 are formed.

[0031] 1, the surface 24 of the metal substrate 20 has exposed regions 27a and 27b exposed from the insulating film 30 at positions different from the first region 26 in a plan view. In the sensor 10 shown in FIG. 1, the surface 24 of the metal substrate 20 has at least two (two in the embodiment) exposed regions 27a and 27b sandwiching the conductive film pattern 40 in a plan view.

[0032] Fig. 8 is a conceptual diagram in which the regions of the surface 24 of the metal substrate 20 shown in Fig. 2 in the sensor 10 shown in Fig. 1 are distinguished by hatching, etc. As shown in Fig. 8, the surface 24 of the metal substrate 20 has a region 28 under the conductive film pattern, a first region 26, exposed regions 27a and 27b, a non-exposed region 29, etc.

[0033] The conductive film pattern lower region 28 is a region directly below the conductive film pattern 40, and corresponds to the conductive film pattern forming region 46 shown in FIG. 1 in plan view. The first region 26 exists in the first direction D1 from the conductive film pattern forming region 46 shown in FIG. 1 in plan view. The conductive film pattern lower region 28 and the first region 26 are all covered with the insulating film 30.

[0034] The exposed regions 27a and 27b are formed on both ends of the surface 24 in the second direction D2, and are arranged at positions in the second direction D2 that do not overlap with the conductive film pattern 40. The insulating film 30 is not formed on the exposed regions 27a and 27b, and the exposed regions 27a and 27b are exposed from the insulating film 30.

[0035] The non-exposed region 29 is formed between the first region 26 and the exposed regions 27a, 27b. Like the exposed regions 27a, 27b, the non-exposed region 29 is disposed at a position in the second direction D2 that does not overlap with the conductive film pattern 40. Furthermore, the non-exposed region 29 does not overlap with the exposed regions 27a, 27b either in the second direction D2. The non-exposed region 29 is covered with an insulating film 30. The width of the non-exposed region 29 in the second direction D2 can be narrower than the width of the first region 26 in the second direction D2 and wider than the width of the resistive film 42 (the width in the direction perpendicular to the conductive path). Forming such a non-exposed region 29 between the first region 26 and the exposed regions 27a, 27b is also preferable in order to reliably ensure insulation between the surface 24 of the metal base 20 and the conductive film pattern 40.

[0036] Here, a problem that occurs when using a metal substrate 20 having a surface 24 on which streaks 25 are formed will be described using a sensor 810 according to a reference example shown in Fig. 9. Fig. 9 is a plan view of the sensor 810 according to the reference example. The sensor 810 is similar to the sensor 10 shown in Fig. 1 except that the planar shape of the insulating film 830 and the position of the region where the surface 24 of the metal substrate 20 is exposed from the insulating film 830 are different.

[0037] 9, in the sensor 810, the insulating film 830 is formed to cover the surface 24 of the metal base material 20 except for both end portions in the first direction D1. As a result, in the sensor 810, the surface 24 on which the streaks 25 are formed has a first-direction exposed region 826 that exists in the first direction D1 in a plan view from the conductive film pattern formation region 46 on which the conductive film pattern 40 is formed but is exposed from the insulating film 830.

[0038] 9 , a sensor 810 having a first direction exposed region 826 formed therein has a problem in that etching residues 51 extending along the first direction D1 in a plan view can cause a short circuit between the conductive film pattern 40 and the surface 24 (first direction exposed region 826) of the metal base material 20. This is because the insulating film 830 formed on the surface 24 on which the streaks 25 are formed is prone to having grooves and irregularities that trace the streaks 25, which can cause the thickness of the conductive film formed on the insulating film 830 to be non-uniform. Therefore, when a metal base material 20 having a surface 24 on which the streaks 25 are formed is used, etching residues 51 extending in the first direction D1, the same as the streaks 25, tend to be formed on the insulating film 830 as shown in FIG. 9 , when the conductive film pattern 40 is formed by etching the conductive film formed on the insulating film 830.

[0039] 10(a) and 10(b) are conceptual diagrams illustrating a manufacturing process in which etching residue 51 forms a short-circuit path in sensor 810, and are schematic cross-sectional views of sensor 810 during manufacturing. As shown in FIG. 10(a), when an insulating film 830a is formed on surface 24 of metal base material 20 and then a conductive film pattern 40 is formed on insulating film 830a, etching residue 51 is generated that extends in first direction D1, the same as streaks 25. Note that insulating film 830a shown in FIG. 10(a) is formed over the entire surface 24 of metal base material 20.

[0040] 10(a) is formed, a part of the insulating film 830a shown in FIG. 10(a) is removed to form a first direction exposed region 826 in which the surface 24 of the metal base material 20 is exposed (FIG. 10(b)). Then, as shown in FIG. 10(b), an etching residue 51 generated during the formation of the conductive film pattern 40 connects the surface 24 of the metal base material 20 and the conductive film pattern 40, forming a short-circuit path.

[0041] 11(a) to 11(c) are conceptual diagrams illustrating another manufacturing process in which etching residue 52 forms a short-circuit path in sensor 810, and are schematic cross-sectional views of sensor 810 during manufacturing. Even when first direction exposed region 826 is formed before forming conductive film pattern 40 as shown in FIG. 11(a), etching residue 52 (etching residue when etching film 40a that is the base of conductive film pattern 40) extending in the same first direction D1 as streaks 25 connects surface 24 of metal base material 20 and conductive film pattern 40, forming a short-circuit path, as shown in FIGS. 11(b) and 11(c).

[0042] Therefore, as shown in Figure 9, in a sensor 810 in which a first direction exposed region 826 is formed on the surface 24 that exists in the first direction D1 in a planar view from the conductive film pattern formation region 46 but is exposed from the insulating film 830, short circuits are likely to occur due to etching residue 51.

[0043] 1, on the surface 24, the first region 26 that exists in the first direction D1 from the conductive film pattern formation region 46 in a plan view is covered with the insulating film 30. Therefore, even if an etching residue 51 that extends in the first direction D1 like the streaks 25 as shown in FIG. 9 occurs, the etching residue 51 does not connect to the surface 24 of the metal base material 20, and therefore does not form a short-circuit path, unlike the case shown in FIG.

[0044] 1 on the surface 24 of the metal base material 20, resistance welding electrodes 71 can be brought into contact with the exposed regions 27a, 27b in a process of fixing the sensor 10 to another member 70, as shown in Fig. 4, to easily weld and fix the sensor 10 to the other member. The sensor 10 detects strain in a member in contact with the metal base material 20, for example, from a change in resistance of the resistive film 42 of the conductive film pattern 40.

[0045] The sensor 10 shown in FIGS. 1 to 4 is manufactured, for example, by the following manufacturing process. First, in manufacturing the sensor 10, a metal substrate 20 as shown in FIG. 2 is prepared. The metal substrate 20 is manufactured, for example, by subjecting a predetermined metal material to mechanical processing such as pressing, cutting, and polishing. In this case, as shown in FIGS. 2 and 3, the surface 24 is not mirror-polished, but rather is left with streaks 25, which can simplify the manufacturing process.

[0046] Next, a multilayer film that will form the insulating film 30 and the conductive film pattern 40 is formed on the surface 24 of the metal substrate 20. The formed film is then microfabricated using semiconductor processing techniques, including etching, to form the insulating film 30 and the conductive film pattern 40. These steps result in a sensor 10 including the metal substrate 20, as shown in FIG. 2 . When using the sensor 10, as shown in FIG. 4 , the sensor 10 including the metal substrate 20 is fixed to another member 70 or the like by resistance welding or the like, and the electrode pads 44, 45 of the conductive film pattern 40 are connected to an external substrate or the like (not shown) by wire bonding or the like. An insulating protective layer may be formed on the conductive film pattern 40 to protect the conductive film pattern 40. The insulating film 30 may also be formed on the metal substrate 20 so that the insulating film 30 has a wraparound portion that wraps around at least a portion of the side surface of the metal substrate 20 that connects to the surface 24.

[0047] By using a metal substrate 20 having a surface 24 on which streaks 25 are formed, such sensor 10 can reduce costs and improve production efficiency by, for example, omitting the mirror polishing process. Furthermore, because first region 26 is covered with insulating film 30, even if etching residue 51 along the streaks 25 of the conductive film forming conductive film pattern 40 occurs during the manufacturing process, insulation between conductive film pattern 40 and surface 24 of metal substrate 20 can be suitably ensured. Furthermore, by providing exposed regions 27a, 27b at positions different from first region D1 on surface 24, it is possible to avoid the occurrence of a short circuit between conductive film pattern 40 and surface 24 of metal substrate 20 due to etching residue 51 of the conductive film, while ensuring an area on surface 24 for contacting a resistance welding electrode, etc.

[0048] Second embodiment Fig. 5 is a plan view showing a sensor 110 according to the first embodiment. The sensor 110 is similar to the sensor 10 shown in Fig. 1 in other respects, except for the orientation of the conductive film pattern 140 relative to the first direction D1. The explanation of the sensor 110 will focus on the differences from the sensor 10, and common reference numerals will be used to denote common features with the sensor 10, and explanations thereof will be omitted.

[0049] As shown in FIG. 5, the conductive film pattern 140 of the sensor 110, like the conductive film pattern 40 of the sensor 10 shown in FIG. 1, has two electrode pads 144, 145 and a resistive film 142 electrically connecting the two electrode pads 144, 145. The resistive film 142 of the conductive film pattern 140 has a rectangular wave or meandering shape with the second direction D2 as its amplitude direction, which is different from the amplitude direction of the resistive film 42 shown in FIG. 1. The two electrode pads 144, 145 are aligned along the first direction D1, which differs from the sensor 10 (see FIG. 1) in which the two electrode pads 44, 45 are aligned along the second direction D2. In the sensor 110, two of the at least two exposed regions 27a, 27b (two in this embodiment) sandwich the conductive film pattern 140 in the amplitude direction of the rectangular wave or meandering shape of the resistive film 142 in a plan view.

[0050] As can be seen from a comparison between the sensor 10 shown in FIG. 1 and the sensor 110 shown in FIG. 5, the shape and orientation of the conductive film patterns 40, 140 formed on the surface 24 of the metal substrate 20 via the insulating film 30 are not particularly limited, and can be any shape that allows deformation of the metal substrate 20 to be detected from changes in resistance. As shown in FIG. 5, by configuring the two exposed regions 27a, 27b to sandwich the conductive film pattern 140 in the amplitude direction of the meandering shape of the resistive film 142 in a plan view, the direction connecting the fixing positions of the metal substrate 20 to another member 70 (see FIG. 4) can be aligned with the direction of strain to be detected by contacting the two exposed regions 27a, 27b with electrodes for resistance welding, for example. This allows strain occurring in the other member 70 to be efficiently transmitted to the metal substrate 20, thereby increasing the sensitivity of strain detection. 5, the first region 26, which is located in the first direction D1 in plan view from the conductive film pattern forming region 146 where the conductive film pattern 140 is formed, is covered with the insulating film 30, and therefore, insulation between the conductive film pattern 40 and the surface 24 of the metal base material 20 can be suitably ensured. In addition, the sensor 110 has similar effects to the sensor 10 in terms of the points in common with the sensor 10.

[0051] Third embodiment Fig. 6 is a plan view showing a sensor 210 according to the second embodiment. Sensor 210 differs in the shapes and arrangement of exposed regions 227a, 227b and non-exposed region 229, but is otherwise similar to sensor 10 shown in Fig. 1. The description of sensor 210 will focus on differences from sensor 10, and common reference numerals will be used to denote common features with sensor 10, and description thereof will be omitted.

[0052] 6, two exposed regions 227a and 227b are arranged on the surface 24 of the metal base material 20 in the sensor 210 so as to sandwich the conductive film pattern 40 from both sides in the second direction D2 in a plan view. However, the exposed regions 227a and 227b of the sensor 210 are not located at the ends of the metal base material 20 in the second direction D2. As shown in FIG. 6, on the surface 24 of the metal base material 20, the peripheries of the exposed regions 227a and 227b are surrounded by non-exposed regions 229 that are covered by the insulating film 230. That is, the exposed regions 227a and 227b of the sensor 210 are exposed from the insulating film 230 by through holes formed in the insulating film 230.

[0053] 6, the shape and area of ​​exposed regions 227a and 227b are not particularly limited and can be any shape and area depending on the application. In addition, sensor 110 has similarities with sensor 10 and exhibits the same effects as sensor 10.

[0054] Fourth embodiment Fig. 7 is a plan view showing a sensor 310 according to the third embodiment. Sensor 310 differs in that it has four exposed regions 327a, 327b, 327c, and 327d, but is otherwise similar to sensor 10 shown in Fig. 1. The description of sensor 310 will focus on the differences from sensor 10, and common reference numerals will be used to denote common features with sensor 10, and description thereof will be omitted.

[0055] 7, exposed regions 327a, 327b, 327c, and 327d that are exposed from the insulating film 330 are formed at the four corners of the rectangular surface 24 of the metal base material 20 in the sensor 310. Each of the exposed regions 327a, 327b, 327c, and 327d has a substantially square shape.

[0056] 7, the number and arrangement of exposed areas 327a, 327b, 327c, and 327d are not particularly limited, and surface 24 may have three or more exposed areas 327a, 327b, 327c, and 327d. Otherwise, sensor 310 has similar effects to sensor 10 in common with sensor 10.

[0057] Although the sensor according to the present disclosure has been described above using multiple embodiments, it goes without saying that the technical scope of the sensor according to the present disclosure is not limited to the above-described embodiments and includes many other embodiments and modifications. For example, the number of conductive film patterns 40, 140 formed on the surface 24 of the metal substrate 20 is not limited to one, and two or more conductive film patterns 40, 140 may be formed on the surface 24 of the metal substrate 20 with an insulating film interposed therebetween. Furthermore, when multiple conductive film patterns 40, 140 are formed, the conductive film patterns 40, 140 may be electrically independent of each other or may be electrically connected to each other to form a bridge circuit or the like. [Explanation of symbols]

[0058] 10, 110, 210, 310, 810...sensor 20...Metal base material 22...Back surface 24…Surface 25...Stripes 26...First area 27a, 27b, 227a, 227b, 327a, 327b, 327c, 327d...Exposed area 27b…Exposed area 28...Area under the conductive film pattern 29, 229...non-exposed area 30, 230, 330, 830...insulating film 40, 140...Conductive film pattern 42, 142...resistive film 44, 45, 144, 145...Electrode pads 46, 146...Conductive film pattern forming area 70...Other parts 71...Electrode D1…first direction D2…Second direction 826...First direction exposure area 51, 52...etching residue

Claims

1. a metal substrate having a surface on which striations are formed along a first direction in a plan view; a conductive film pattern formed on the surface via an insulating film, a first region on the surface, which is located in the first direction in a plan view from a conductive film pattern formation region in which the conductive film pattern is formed, is covered with the insulating film; The sensor has an exposed region exposed from the insulating film at a position different from the first region in a plan view on the surface.

2. The sensor according to claim 1 , wherein the surface has at least two exposed regions sandwiching the conductive film pattern in a plan view.

3. the conductive film pattern has a pattern portion that is rectangular wave-shaped or meander-shaped in plan view, The sensor according to claim 2 , wherein two of the at least two exposed regions sandwich the conductive film pattern in the amplitude direction of the rectangular wave shape or the meandering shape in a plan view.

4. 4. The sensor according to claim 1, wherein a surface roughness Ra of the surface in a second direction perpendicular to the first direction in a plan view is 0.05 μm or more and 1 μm or less.

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