Method for manufacturing laminate film and second laminate film, and method for manufacturing strain sensor

Abstract

To provide a laminate film from which a resistance layer having a low absolute value of a coefficient of a resistance temperature can be formed even when heated at a low temperature, and a strain sensor.SOLUTION: A laminate film 1 has an insulating base material resin film 2, and a resistance layer 3 in this order in a thickness direction. The resistance layer 3 contains chromium nitride. A coefficient of a resistance temperature of the resistance layer 3 is -400 ppm / °C or more and -200 ppm / °C or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate film, a method for manufacturing a second laminate film, and a method for manufacturing a strain sensor, and more particularly to a laminate film, a method for manufacturing a second laminate film using the laminate film, and a method for manufacturing a strain sensor using the laminate film. [Background technology]

[0002] BACKGROUND ART Conventionally, a strain sensor has been known that includes an insulating substrate and a patterned Cr—N thin film disposed on the surface of the insulating substrate (see, for example, Patent Document 1 below).

[0003] In Patent Document 1, a strain sensor is manufactured by first forming a Cr-N thin film on the surface of an insulating substrate to produce a thin film laminate film, then heat treating it at 300°C and patterning the Cr-N thin film. In Patent Document 1, the absolute value of the temperature coefficient of resistance (TCR) of the Cr-N thin film is reduced by the heat treatment at 300°C, improving the stability of the strain sensor.

[0004] Furthermore, a hard silicon substrate is used as an insulating substrate that can withstand the above-mentioned high-temperature heat treatment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-31633 Summary of the Invention [Problem to be solved by the invention]

[0006] However, depending on the application and purpose, it may be desirable to use a substrate made of a resin with low heat resistance, but such a substrate cannot be heat-treated at the above-mentioned temperatures, and the absolute value of the temperature coefficient of resistance cannot be reduced.

[0007] The present invention provides a laminated film that can form a resistive layer with a low absolute value of the temperature coefficient of resistance even when heated at a low temperature, a method for manufacturing a second laminated film using the laminated film, and a method for manufacturing a strain sensor using the laminated film. [Means for solving the problem]

[0008] The present invention [1] is a laminated film comprising an insulating base resin film and a resistive layer in that order in the thickness direction, the resistive layer containing chromium nitride, and the resistive layer having a temperature coefficient of resistance of -400 ppm / °C or more and -200 ppm / °C or less.

[0009] The present invention [2] includes the laminated film according to the above [1], wherein the resistive layer has a body-centered cubic lattice structure.

[0010] The present invention [3] includes the laminated film according to the above [1] or [2], in which the resistive layer does not have an A15 type structure.

[0011] The present invention [4] includes the laminated film according to any one of the above [1] to [3], wherein in the chromium nitride, the molar ratio of nitrogen atoms to 100 molar parts of chromium atoms is 3.0 parts by molar or more and less than 9 parts by molar.

[0012] The present invention [5] includes the laminated film according to any one of the above [1] to [4], wherein the thickness of the resistive layer is 10 nm or more and 150 nm or less.

[0013] The present invention [6] includes the laminate film according to any one of the above [1] to [5], wherein the thickness of the base resin film is 10 μm or more and 200 μm or less.

[0014] The present invention [7] includes the laminated film according to any one of the above [1] to [6], wherein the material of the base resin film is polyimide.

[0015] The present invention [8] includes a method for producing a second laminate film, comprising a preparation step of preparing the laminate film described in any one of [1] to [7] above, and a heating step of heating the laminate film at 200°C or less.

[0016] The present invention [9] includes the method for producing the second laminate film described in [8] above, wherein in the heating step, the temperature coefficient of resistance of the resistive layer after heating is set to be not less than -100 ppm / °C and not more than 100 ppm / °C.

[0017] The present invention

[10] includes a method for manufacturing a strain sensor, comprising a preparation step of preparing the laminated film described in any one of the above [1] to [7], a heating step of heating the laminated film at 200°C or less, and a patterning step of patterning the resistive layer in the laminated film. [Effects of the Invention]

[0018] The laminated film of the present invention includes a resistive layer having a predetermined temperature coefficient of resistance, and therefore, even when the laminated film is heated at a low temperature, a resistive layer having a low absolute value of the temperature coefficient of resistance can be formed.

[0019] The method for producing the second laminate film of the present invention uses the laminate film of the present invention to produce the second laminate film, and therefore, even when heated at a low temperature, a resistance layer having a low absolute value of the temperature coefficient of resistance can be formed.

[0020] The method for producing a strain sensor of the present invention uses the laminated film of the present invention to produce a strain sensor, and therefore, a strain sensor with excellent stability can be obtained. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a cross-sectional view of one embodiment of the laminated film of the present invention. [Figure 2] FIG. 2 shows a strain sensor in which the resistive layer shown in FIG. 1 is patterned, with FIG. 2A being a cross-sectional view and FIG. 2B being a plan view. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment of the laminated film and strain sensor of the present invention will be described with reference to FIGS. 1 to 2B.

[0023] [Laminated film] The laminated film 1 is used to manufacture a second laminated film (described later) and a strain sensor 15 (see FIGS. 2A and 2B) (described later).

[0024] This laminated film 1 is distributed alone as a precursor of the second laminated film and the strain sensor 15.

[0025] This laminated film 1 has a flat plate shape extending in a plane direction perpendicular to the thickness direction. Specifically, the laminated film 1 includes a base resin film 2 and a resistance layer 3 arranged in this order toward one side in the thickness direction. Specifically, the laminated film 1 includes the base resin film 2 and the resistance layer 3 arranged on one side of the base resin film 2.

[0026] [Base resin film] The base resin film 2 is insulating. The base resin film 2 forms the other surface in the thickness direction of the laminated film 1. The base resin film 2 has a flat plate shape extending in the surface direction.

[0027] Examples of materials for the base resin film include resins such as polyimide, polyester, polyethylene terephthalate, and polyethylene naphthalate. Polyimide is preferably used as the material for the base resin film 2. If the base resin film 2 is polyimide, it can be heated up to 200°C.

[0028] The linear expansion coefficient of the base resin film 2 is, for example, 30 ppm / °C or less, or preferably 15 ppm / °C or less.

[0029] The thickness of the base resin film 2 is not particularly limited, and is, for example, 2 μm or more, preferably 10 μm or more, more preferably 20 μm or more, from the viewpoint of suppressing the occurrence of wrinkles, and is, for example, 500 μm or less, preferably 300 μm or less, more preferably 200 μm or less, from the viewpoint of roll-to-roll transport.

[0030] One surface of the base resin film 2 in the thickness direction may be subjected to treatment such as corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, sputter etching treatment, etc. to improve adhesion to the resistance layer 3.

[0031] The number of base resin films 2 in the laminated film 1 is not particularly limited, but is preferably one.

[0032] [Resistance layer] The resistive layer 3 is a layer that is heated and patterned when the strain sensor 15 (see FIGS. 2A and 2B) is manufactured from the laminated film 1.

[0033] The resistive layer 3 is disposed on one thickness-wise surface of the base resin film 2. The resistive layer 3 forms one thickness-wise surface of the laminated film 1. Specifically, the resistive layer 3 is in contact with the entire one thickness-wise surface of the base resin film 2.

[0034] The resistive layer 3 contains chromium nitride. Specifically, the material of the resistive layer 3 contains chromium nitride as a main component. On the other hand, the material of the resistive layer 3 is allowed to contain, for example, inevitable impurities. The proportion of inevitable impurities in the resistive layer 3 is, for example, 1 atomic % or less, preferably 0.1 atomic % or less, and more preferably 0.05 atomic % or less. Preferably, the resistive layer 3 is made of chromium nitride.

[0035] In chromium nitride, the molar ratio of nitrogen atoms to 100 molar parts of chromium atoms is, for example, 3.0 molar parts or more, preferably 3.5 molar parts or more, and for example, 10 molar parts or less, preferably less than 9.0 molar parts, more preferably 8.0 molar parts or less, and even more preferably 6.0 molar parts or less.

[0036] If the molar part is equal to or greater than the lower limit, the temperature coefficient of resistance of the resistance layer 3 (specifically, the temperature coefficient of resistance before heating, described later) can be adjusted to fall within a predetermined range, described later.

[0037] If the molar part is equal to or less than the upper limit, the temperature coefficient of resistance of the resistance layer 3 (specifically, the temperature coefficient of resistance before heating, described later) can be adjusted to a predetermined range described later.

[0038] The method for determining the molar parts will be described in detail in the Examples below.

[0039] Furthermore, the crystal structure of the chromium nitride in the resistive layer 3 does not include the A15 structure, but has a body-centered cubic lattice structure.

[0040] When the resistive layer 3 has a body-centered cubic lattice structure, the temperature coefficient of resistance of the resistive layer 3 (more specifically, the temperature coefficient of resistance before heating, described later) can be adjusted to a predetermined range described later.

[0041] If the resistive layer 3 does not contain the A15 structure, the crystallinity of the resistive layer 3 can be increased and the stability can be improved without heating at a high temperature in the heating step described below.

[0042] The method for measuring the crystal structure of the resistance layer 3 will be described in detail in the examples below.

[0043] The resistance temperature coefficient of the resistive layer 3 (specifically, the resistance temperature coefficient before heating) is −400 ppm / ° C. or more, preferably −300 ppm / ° C. or more and −200 ppm / ° C. or less.

[0044] If the temperature coefficient of resistance is equal to or greater than the lower limit, the absolute value of the temperature coefficient of resistance (specifically, the temperature coefficient of resistance after heating) can be reduced even when the resistive layer 3 is heated at a low temperature, thereby providing a strain sensor 15 with excellent stability.

[0045] On the other hand, if the temperature coefficient of resistance is less than the lower limit, the absolute value of the temperature coefficient of resistance (specifically, the temperature coefficient of resistance after heating) cannot be reduced even if the resistance layer 3 is heated at a low temperature, and therefore, a strain sensor 15 with excellent stability cannot be obtained.

[0046] Furthermore, if the temperature coefficient of resistance is equal to or less than the upper limit, the absolute value of the temperature coefficient of resistance (specifically, the temperature coefficient of resistance after heating) can be reduced even when the resistance layer 3 is heated at a low temperature, thereby providing a strain sensor 15 with excellent stability.

[0047] On the other hand, if the temperature coefficient of resistance exceeds the upper limit, the absolute value of the temperature coefficient of resistance (specifically, the temperature coefficient of resistance after heating) cannot be reduced even if the resistive layer 3 is heated at a low temperature, and therefore, a strain sensor 15 with excellent stability cannot be obtained.

[0048] The method for determining the temperature coefficient of resistance of the resistive layer 3 will be described in detail in the examples below.

[0049] The thickness of the resistive layer 3 is, for example, 5 nm or more, preferably 10 nm or more from the viewpoint of increasing the gauge factor of the resistive layer 3, and is, for example, 150 nm or less, preferably 120 nm or less from the viewpoint of suppressing the occurrence of cracks in the resistive layer 3.

[0050] The number of resistance layers 3 in the laminated film 1 is not particularly limited, but is preferably 1. Specifically, the number of resistance layers 3 per base resin film 2 is preferably 1.

[0051] [Laminated film manufacturing method] In the method for producing the laminated film 1, for example, the laminated film 1 is formed by a roll-to-roll method.

[0052] For example, while conveying a long substrate resin film 2, the resistive layer 3 is formed on one surface in the thickness direction of the substrate resin film 2. Examples of the film formation method include sputtering, vacuum deposition, and ion plating. Preferably, sputtering is used, and more preferably, reactive sputtering is used.

[0053] In reactive sputtering, the target is made of chromium, and the sputtering gas is a mixture of an inert gas such as argon and nitrogen. The volume ratio of nitrogen to 100 volume parts of the inert gas is, for example, 0.5 to 15 volume parts.

[0054] In this way, a laminated film 1 including the base resin film 2 and the resistance layer 3 is produced.

[0055] This laminated film 1 can be suitably used to manufacture a second laminated film and a strain sensor.

[0056] [Method for manufacturing the second laminated film] The second laminate film is obtained by heating the laminate film 1 (more specifically, the resistance layer 3 in the laminate film 1). That is, the second laminate film is the laminate film 1 after heating.

[0057] Specifically, the method for producing the second laminate film includes a preparation step of preparing the laminate film 1, and a heating step of heating the laminate film 1 at a predetermined temperature.

[0058] In the preparation step, the laminated film 1 is prepared.

[0059] In the heating step, the laminated film 1 (resistive layer 3) is heated to increase the crystallinity of the resistive layer 3 and improve its stability.

[0060] As for heating conditions, the heating temperature is a temperature at which the base resin film 2 is not damaged by heating, and is, for example, 200° C. or less, preferably 160° C. or less, and for example, 80° C. or more, preferably 100° C. or more, more preferably 120° C. or more. The heating time is, for example, 20 minutes or more, preferably 50 minutes or more, and for example, 240 minutes or less, preferably 120 minutes or less.

[0061] If the heating temperature is equal to or lower than the above upper limit, damage to the base resin film 2 due to heating can be suppressed.

[0062] By the above-described heating, the absolute value of the temperature coefficient of resistance of the resistive layer 3 after heating can be reduced.

[0063] More specifically, as described above, since the temperature coefficient of resistance of the resistive layer 3 before heating is within a predetermined range, the absolute value of the temperature coefficient of resistance of the resistive layer 3 after heating can be made small.

[0064] Specifically, the temperature coefficient of resistance of the resistive layer 3 after heating is, for example, −100 ppm / °C or more, preferably −80 ppm / °C or more, more preferably −50 ppm / °C or more, even more preferably −20 ppm / °C or more, and for example, 100 ppm / °C or less, preferably 80 ppm / °C or less, more preferably 50 ppm / °C or less, even more preferably 20 ppm / °C or less.

[0065] That is, the absolute value of the temperature coefficient of resistance of the resistive layer 3 after heating is, for example, 100 or less, preferably 80 or less, more preferably 50 or less, and further preferably 20 or less.

[0066] If the absolute value of the temperature coefficient of resistance is equal to or less than the upper limit, the second laminate film will have excellent stability.

[0067] [Strain sensor manufacturing method] The method for manufacturing the strain sensor 15 includes a preparation step of preparing the laminated film 1, a heating step of heating the laminated film 1 at a predetermined temperature, and a patterning step of patterning the resistance layer 3 on the laminated film 1.

[0068] In the preparation step, the laminated film 1 is prepared.

[0069] In the heating step, the laminated film 1 (resistive layer 3) is heated to increase the crystallinity of the resistive layer 3 and improve its stability.

[0070] The heating conditions are the same as those in the heating step of the method for producing the second laminate film described above, and the heating temperature is a temperature at which the base resin film 2 is not damaged by heating, and is, for example, 200° C. or less, preferably 160° C. or less, and for example, 80° C. or more, preferably 100° C. or more, more preferably 120° C. or more. The heating time is, for example, 20 minutes or more, preferably 50 minutes or more, and for example, 240 minutes or less, preferably 120 minutes or less.

[0071] If the heating temperature is equal to or lower than the above upper limit, damage to the base resin film 2 due to heating can be suppressed.

[0072] By the above-described heating, the absolute value of the temperature coefficient of resistance of the resistive layer 3 after heating can be reduced.

[0073] More specifically, as described above, since the temperature coefficient of resistance of the resistive layer 3 before heating is within a predetermined range, the absolute value of the temperature coefficient of resistance of the resistive layer 3 after heating can be made small.

[0074] Specifically, the temperature coefficient of resistance of the resistive layer 3 after heating is, for example, −100 ppm / °C or more, preferably −80 ppm / °C or more, more preferably −50 ppm / °C or more, even more preferably −20 ppm / °C or more, and for example, 100 ppm / °C or less, preferably 80 ppm / °C or less, more preferably 50 ppm / °C or less, even more preferably 20 ppm / °C or less.

[0075] That is, the absolute value of the temperature coefficient of resistance of the resistive layer 3 after heating is, for example, 100 or less, preferably 80 or less, more preferably 50 or less, and further preferably 20 or less.

[0076] If the absolute value of the temperature coefficient of resistance is equal to or less than the upper limit, the strain sensor 15 has excellent stability.

[0077] 2A, in the patterning step, the resistive layer 3 in the laminated film 1 is patterned to form a resistive pattern 4. Examples of the patterning of the resistive layer 3 include etching, specifically dry etching and wet etching, preferably dry etching, and more preferably laser etching.

[0078] The resistance pattern 4 integrally includes a strain sensor portion 5, a terminal 6, and a wiring 7.

[0079] 2B, the strain sensor unit 5 has a generally zigzag shape in plan view. Specifically, the strain sensor unit 5 has a plurality of first wires 8, a plurality of first connection wires 9, and a plurality of second connection wires 10.

[0080] Each of the multiple first lines 8 extends along a first direction (a direction included in the surface direction). The multiple first lines 8 are aligned and spaced apart in a second direction (a direction included in the surface direction and perpendicular to the first direction).

[0081] The plurality of first connection lines 9 connects the first direction end portions of the first lines 8 adjacent to each other in the second direction.

[0082] The multiple second connection lines 10 connect the other ends in the first direction of the first lines 8 that are adjacent in the second direction. When projected in the first direction, the first connection lines 9 and the second connection lines 10 are arranged alternately.

[0083] The terminal 6 is spaced apart in the surface direction from the strain sensor unit 5. The terminal 6 has, for example, a land shape that is generally rectangular in plan view. Two terminals 6 are provided with a space between them.

[0084] The wires 7 connect the two terminals 6 to both ends of the strain sensor unit 5 .

[0085] In the strain sensor section 5, one conductive path is formed from one terminal 6, passing through one wire 7, the strain sensor section 5 and another wire 7, to the other terminal 6.

[0086] The dimensions of the strain sensor unit 5 are set appropriately depending on the application and purpose. The widths of the first wires 8, the first connection wires 9, and the second connection wires 10 are, for example, 1 μm or more, preferably 5 μm or more, and more preferably 10 μm or more, and for example, 150 μm or less, preferably 100 μm or less, and more preferably 70 μm or less.

[0087] The shape of the base resin film 2 is also set appropriately depending on the use and purpose of the strain sensor 15, and is formed to desired dimensions by, for example, outer shaping.

[0088] Next, a method for placing the strain sensor 15 on the test object 20 and measuring the amount of strain (amount of deformation) of the test object 20 will be described.

[0089] 2A, the laminated film 1 of the strain sensor 15 is attached to the surface of the specimen 20 via an adhesive layer 21. Lead wires 23 are connected to the two terminals 6 via a conductive adhesive layer 22. The lead wires 23 are electrically connected to an external resistance measurement circuit (not shown).

[0090] When the object 20 is strained, the resistance value of the strain sensor section 5 changes, and based on this, the resistance measurement circuit calculates the amount of strain.

[0091] Specifically, when the specimen 20 stretches in the first direction, a tensile strain is applied to the first wire 8, the cross-sectional area of the first wire 8 decreases, and the resistance of the strain sensor unit 5 increases. On the other hand, when the specimen 20 contracts, a compressive strain is applied to the first wire 8, the cross-sectional area of the first wire 8 increases, and the resistance of the strain sensor unit 5 decreases. The amount of strain in the specimen 20 is calculated from this change in resistance.

[0092] (Effects of one embodiment) This laminated film 1 includes a resistive layer 3 having a predetermined temperature coefficient of resistance. Therefore, even if this laminated film is heated at a low temperature, a resistive layer with a low absolute value of the temperature coefficient of resistance can be formed. As a result, a strain sensor 15 with excellent stability can be obtained.

[0093] This method for manufacturing the second laminate film uses the laminate film 1 to manufacture the second laminate film. Therefore, even when heated at a low temperature, it is possible to form a resistance layer 3 having a low absolute value of the temperature coefficient of resistance. As a result, it is possible to obtain a strain sensor 15 with excellent stability.

[0094] In this method for manufacturing the strain sensor 15, the strain sensor 15 is manufactured using the laminated film 1. Therefore, the strain sensor 15 having excellent stability can be obtained.

[0095] (Variation) In the following modifications, the same components and steps as those in the above-described embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, each modification can achieve the same effects as those in the above-described embodiment unless otherwise specified. Furthermore, the embodiment and its modifications can be combined as appropriate.

[0096] In one embodiment, the heating is performed before the patterning of the resistive layer 3, but may be performed after the patterning of the resistive layer 3, for example.

[0097] The base resin film 2 may include, on one surface in the thickness direction thereof, a functional layer (not shown) such as a hard coat layer, an easy-adhesion layer, or an antistatic layer.

[0098] The strain sensor 15 can further include a cover layer 12 (dotted line) that covers the strain sensor section 5 and is made of resin.

[0099] In one embodiment, one is exemplified as a suitable number of resistance layers 3 in the laminate film 1, but it may also be two, for example, although not shown. In this case, two resistance layers 3 are disposed on both sides in the thickness direction of the base resin film 2. That is, in a suitable example of this modification, the number of resistance layers 3 per base resin film 2 is preferably two. [Example]

[0100] The present invention will be described in more detail below with reference to examples and comparative examples. It should be noted that the present invention is in no way limited to these examples and comparative examples. The specific numerical values of the blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the corresponding upper limit values (numeric values defined as "equal to or less than" or "less than") or lower limit values (numeric values defined as "equal to or greater than" or "exceeding") of the blending ratios (content ratios), physical property values, parameters, etc. described in the "Description of the Invention" above.

[0101] Example 1 A base resin film 2 made of polyimide with a linear expansion coefficient of 13 ppm / ° C. and having a thickness of 38 μm was prepared.

[0102] The base resin film 2 was set on a roll-to-roll feed roll and a take-up roll, and was also set in a sputtering device disposed between them.

[0103] Next, the vacuum level in the sputtering device was set to 1×10 -3After evacuating the chamber to a pressure of 100 Pa or less, a resistive layer 3 made of chromium nitride was formed by reactive pulse DC sputtering (pulse width: 1 μs, frequency: 100 kHz) under the following conditions: The target was made of metallic chromium.

[0104] Target: Metal chrome, 500mm x 150mm flat plate Power: 5kW (power density: 6.7W / cm 2 ) Magnetic flux density (target surface): 30mT~100mT Substrate temperature: 150℃ Sputtering gas: Argon and nitrogen mixture Film formation pressure: 0.085Pa The ratio of nitrogen gas was adjusted so that the ratio of the number of moles of nitrogen atoms to the number of moles of chromium atoms was as shown in Table 1.

[0105] In this way, a laminated film 1 including the base resin film 2 and the resistance layer 3 was produced.

[0106] Next, the laminated film 1 was heated at 130° C. for 60 minutes.

[0107] The laminated film 1 was then cut to a size of 10 mm x 200 mm, and a resistive pattern 4 consisting of a zigzag strain sensor section 5, terminals 6, and wiring 7 was formed from the resistive layer 3 by laser patterning. The line width of the strain sensor section 5 was 30 μm. The resistance of the resistive pattern 4 was adjusted to approximately 10 kΩ, and the resistance of the strain sensor section 5 was adjusted to 30 times the resistance of the wiring 7. In this way, a strain sensor 15 was obtained.

[0108] Examples 2 to 6, Comparative Examples 1 to 6 The laminated film 1 and further the strain sensor 15 were obtained in the same manner as in Example 1, except that the ratio of the number of moles of nitrogen atoms to the number of moles of chromium atoms and the heating conditions were changed according to Table 1. Specifically, the ratio of nitrogen in the sputtering gas was adjusted.

[0109] (evaluation) The following items were evaluated, and the results are shown in Table 1.

[0110] <Temperature coefficient of resistance> The temperature of the resistance layer 3 of the laminated film 1 and the strain sensor portion 5 of the strain sensor 15 in each of the Examples and Comparative Examples was set to 5°C. A tester was connected to each of the two terminals 6, and the two-terminal resistance at 5°C was measured by passing a constant current and reading the voltage. Similarly, the two-terminal resistance was measured at 25°C and 45°C.

[0111] The resistance temperature coefficient calculated from the resistance values at 5°C and 25°C and the average value of the resistance temperature coefficient calculated from the resistance values at 25°C and 45°C were calculated as the resistance temperature coefficient of the resistive layer 3 of the laminated film 1 (the resistance temperature coefficient of the resistive layer 3 before heating) and the resistance temperature coefficient of the strain sensor part 5 (the resistance temperature coefficient of the resistive layer 3 after heating).

[0112] Although the ratio of nitrogen atoms to chromium atoms is the same in Examples 1, 2, and 4, the temperature coefficients of resistance of the resistive layer 3 before heating are different. Specifically, the temperature coefficients of resistance of the resistive layer 3 before heating vary by about ±16.

[0113] Such variations are due to measurement errors in the resistance value and variations within the surface of the resistance layer 3, and are of a degree that does not impair the effects of the present invention.

[0114] The same applies to the third and fourth embodiments.

[0115] <Ratio of nitrogen atoms> The ratio of nitrogen atoms to chromium atoms in the resistive layer 3 of the laminated film 1 of each of the Examples and Comparative Examples was measured by Rutherford backscattering spectroscopy (RBS) under the following conditions. (Measurement conditions) Equipment: National Electrostatics Corporation Pelletron 3SDH Measurement conditions: Incident ions: 4 He ++ Incident energy: 2300 keV Incident angle: 0deg Scattering angle: 160deg Specimen current: 4nA Beam diameter: 2mmΦ In-plane rotation: None Irradiation dose: 40μC

[0116] <Crystalline structure of the resistance layer of the laminated film> The crystal structure of the resistance layer 3 of the laminated film 1 of each of the examples and comparative examples was measured by X-ray diffraction.

[0117] In Examples 1 to 6, the peak at around 39 degrees due to the A15 structure was not observed, but the peak at around 43.8 degrees due to the body-centered cubic lattice structure was observed.

[0118] That is, it is found that the resistance layers 3 of Examples 1 to 6 do not have the A15 structure, but only have a body-centered cubic lattice structure.

[0119] [Table 1] [Explanation of symbols]

[0120] 1. Laminated film 2. Base resin film 3 resistance layer

Claims

1. An insulating base resin film and a resistive layer are arranged sequentially in the thickness direction. The resistive layer is made of chromium nitride, or of chromium nitride and unavoidable impurities of 1 atomic percent or less. The temperature coefficient of resistance of the resistive layer before heating is -400 ppm / °C or higher and -200 ppm / °C or lower. The resistive layer has a body-centered cubic lattice structure, A laminated film characterized in that the resistive layer does not have an A15 type structure.

2. The laminated film according to claim 1, characterized in that the thickness of the resistive layer is 10 nm or more and 150 nm or less.

3. The aforementioned base resin film is characterized in that its thickness is 10 μm or more and 200 μm or less. The laminated film according to claim 1 or 2.

4. The laminated film according to any one of claims 1 to 3, characterized in that the material of the base resin film is polyimide.

5. A preparation step for preparing the laminated film according to any one of claims 1 to 4, A method for manufacturing a second laminated film, characterized by comprising a heating step of heating the laminated film at a temperature of 80°C to 200°C.

6. The method for manufacturing the second laminated film according to claim 5, characterized in that, in the heating step, the temperature coefficient of resistance of the resistive layer after heating at 80°C to 200°C is set to -100 ppm / °C or more and 100 ppm / °C or less.

7. Preparation steps for preparing the laminated film according to any one of claims 1 to 4, A heating step of heating the laminated film to 200°C or below, and A method for manufacturing a strain sensor, characterized by comprising a patterning step of patterning the resistive layer in the laminated film.

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