WO2017094368A1

WO2017094368A1 - Multipoint-measurement strain sensor and production method for same

Info

Publication number: WO2017094368A1
Application number: PCT/JP2016/080579
Authority: WO
Inventors: 一登中村; 弘明上藤; 柴田　淳一
Original assignee: 日本写真印刷株式会社
Priority date: 2015-12-01
Filing date: 2016-10-14
Publication date: 2017-06-08
Also published as: JP2017101983A

Abstract

[Problem] To provide a multipoint-measurement strain sensor that is without conduction defects caused by slippage during lamination and that can reduce materials costs, and to provide a production method for the multipoint-measurement strain sensor. [Solution] This multipoint-measurement strain sensor 31 comprises: a substrate film 34; a plurality of strain-sensing parts 33 that are formed on a first main surface 34a of the substrate film 34; and two-layer routing circuits 37, 38 that are formed on the first main surface 34a of the substrate film 34 to correspond to each of the stain-sensing parts 33 and that have an outer connection terminal part 37b, 38b that is near an outer edge of the substrate film 34. Lower-layer paths 37L, 38L of the routing circuits 37, 38 comprise the same material as the strain-sensing parts 33, and upper-layer paths 37U, 38U of the routing circuits 37, 38 comprise a material that has a lower resistance than the strain-sensing parts.

Description

Strain sensor for multipoint measurement and its manufacturing method

The present invention relates to a strain sensor for multipoint measurement and a manufacturing method thereof.

With regard to the aging problem of social infrastructure that was developed during the high growth period, it has become a challenge to extend the service life, reduce the total cost of maintenance and renewal, and level it by introducing appropriate maintenance methods. It is expected to promote the development of monitoring technology that enables efficient understanding of the state of social infrastructure using IT.

As a measurement form of the monitoring technology, sensors and cameras were installed on structures (concrete structures, steel structures, earth structures, grounds, etc.), and fixed types that are constantly monitored, and sensors and cameras were installed. Although there is a mobile type that regularly monitors using a moving body (vehicle or the like), the current mainstream is a fixed type. As a typical example of the fixed type, a strain sensor is installed in a concrete structure (tunnel wall surface, road surface, etc.) and a steel structure (bridge, etc.), and the secular change of the strain amount is monitored.

As a strain sensor used for such a fixed type monitoring technique, for example, Patent Document 1 discloses a multipoint measurement of a road surface strain where a traveling wheel of a moving body is grounded. Specifically, the strain sensor 1 capable of multipoint measurement has a gauge base 4 having a plurality of resistance strain gauges 3 attached to the back surface of the flexible substrate 2, and a sheet shape on the surface of the flexible substrate 2. The sensor structure portion 6 is configured by bonding the insulating member (cover film) 5 (see FIGS. 20 and 21). The flexible substrate 2 includes a thin-film conductor (a routing circuit) 18 that conducts to the conductor connection portion 14a of the conductor connection portions (tabs) 14a and 14b at both ends of the strain sensing portion 13 of each resistance strain gauge 3. Further, thin film conductors (leading circuits) 19 and 20 are provided which are electrically connected to the conductor connecting portion 14b. The sensor is such that the strain gauge 3 is located in the ground contact area of the wheel on the road surface, and the

end portions

18b, 19b, 20b of the

thin film conductors

18, 19, 20 are located in areas deviating from the ground contact area in the width direction of the wheel. The gauge base 4 of the part 6 is installed on the road surface.

Various embodiments are disclosed in Patent Document 1. For example, the flexible substrate 2 shown in FIGS. 20 and 21 has a two-layer structure including a first layer substrate 7 and a second layer substrate 8. Alternatively, a single layer flexible substrate may be used instead. In FIG. 21, a plurality of strain gauges 3 having a gauge base 12 and a strain sensing unit 13 are used, and these strain gauges 3 are attached to the surface of the gauge base 4. A plurality of strain sensitive portions 13 may be directly formed on the surface of 4 by photoetching or the like. Further, in FIGS. 20 and 21, the gauge lead wires 15a and 15b are connected to the tabs 14a and 14b at both ends of each strain sensing portion 13, respectively, and the conduction between the tab 14a and the thin film conductor 18 is achieved. The tab 14b and the thin film conductors 19 and 20 are electrically connected to each other through the gauge lead wires 15a and 15b, but instead of using the gauge lead wires 15a and 15b, the tabs It is also possible to conduct the electrical connection between 14a and the thin film conductor 18 and the electrical connection between the tab 14b and the thin film conductors 19 and 20.

JP 2009-79976 A

However, in the strain sensor described in Patent Document 1, a gauge base 4 having a plurality of strain sensitive portions 13 and thin film conductors (leading circuits) 18, 19, and 20 corresponding to the strain sensitive portions 13 are provided. Displacement occurs when the flexible substrate 2 is bonded to each other, resulting in poor continuity between the conductive wire connecting portions 14a and 14b at both ends of the strain sensing portion 13 and the thin film conductors (route circuits) 18, 19, and 20 of the flexible substrate 2. There was a problem of waking up. Moreover, since there are many layer structures, there also existed a problem that material cost and by extension manufacturing cost became high.

Therefore, an object of the present invention is to provide a strain sensor for multipoint measurement and a method for manufacturing the same which can reduce a material cost without causing a conduction failure due to misalignment at the time of bonding.

As a means for solving the above-mentioned problems, the first aspect of the present invention includes a base film, a plurality of strain sensitive portions formed on the first main surface of the base film, and the base film. A two-layer routing circuit formed on the first main surface corresponding to each of the strain sensitive parts and having an external connection terminal near the outer edge of the base film, and the lower layer of the routing circuit is Provided is a strain sensor for multipoint measurement which is made of the same material as that of the strain sensitive part and the upper layer of the routing circuit is made of a material whose resistance is lower than that of the strain sensitive part.

Further, the second aspect of the present invention is an insulating cover layer formed on the first main surface of the base film so as to cover the strain sensitive part and the routing circuit except for the external connection terminal part. A strain sensor for multipoint measurement according to a first aspect, further comprising: a conductive terminal protective layer formed to cover the external connection terminal portion of the routing circuit.

Moreover, the 3rd aspect of this invention is a base film, the some 1st distortion | strain sensitivity part formed in the 1st main surface of the said base film, and each said on the 1st main surface of the said base film. Formed in correspondence with the first strain sensing part, formed on the second main surface of the base film, a first routing circuit of a two-layer configuration having an external connection terminal part in the vicinity of the outer edge of the base film, A plurality of second strain sensitive portions that are axially different from each of the first strain sensitive portions, and formed on the second main surface of the base film in correspondence with the second strain sensitive portions, A second routing circuit having a two-layer configuration having an external connection terminal near the outer edge of the material film, and the lower layer of the first and second routing circuits is the same material as the first and second strain sensing parts And the upper layers of the first and second routing circuits are connected to the first and second strain receivers. Providing strain sensor for multipoint measurement, characterized by comprising low-resistance material than the parts.

Moreover, the 4th aspect of this invention is the insulating property formed in the 1st main surface of the said base film, covering the said 1st distortion | strain sensitive part and the said 1st routing circuit except the said external connection terminal part. The first cover layer, the conductive first terminal protective layer formed to cover the external connection terminal portion of the first routing circuit, and the external connection terminal portion on the second main surface of the base film Insulating second cover layer formed to cover the second strain sensing part and the second routing circuit, and conductivity formed to cover the external connection terminal part of the second routing circuit A strain sensor for multipoint measurement according to a third aspect, further comprising: a second terminal protective layer.

The fifth aspect of the present invention provides the strain sensor for multipoint measurement according to any one of the first to fourth aspects, further comprising a lead wire mounted on the external connection terminal portion.

Further, a sixth aspect of the present invention is a method for manufacturing the strain sensor according to the first aspect, wherein the step of laminating two metal layers on the first main surface of the base film and the etching method, Forming a conductive pattern having a two-layer configuration in the shape of a plurality of strain-sensitive portions from a metal layer, and a routing circuit having a two-layer configuration corresponding to each of the conductive patterns, and the shape of the strain-sensitive portions A method of manufacturing a strain sensor for multi-point measurement is provided, which includes only a conductive layer having a two-layer structure, and a step of removing the upper metal layer by an etching method to obtain the strain sensitive part.

Further, the seventh aspect of the present invention is the method for manufacturing the strain sensor according to the first aspect, wherein the step of laminating one metal layer on the first main surface of the base film and the etching method, Only a process of forming a plurality of strain sensitive parts from the metal layer and a conductive pattern having the shape of the routing circuit corresponding to each strain sensitive part, and a conductive pattern having the shape of the routing circuit are printed. A method of manufacturing a strain sensor for multipoint measurement, comprising the step of laminating another metal layer by a method to obtain the routing circuit having a two-layer structure.

Further, an eighth aspect of the present invention is a method for manufacturing a strain sensor according to the third aspect, wherein a step of laminating two metal layers on the first main surface and the second main surface of the base film, respectively. The two-layered conductive pattern in the shape of a plurality of the first strain sensitive parts from the metal layer on the first main surface side by the etching method, and the first of the two-layered structure corresponding to each of the conductive patterns Forming a routing circuit, and simultaneously forming a plurality of second strain sensing portions in the shape of a plurality of second strain sensing portions from the metal layer on the second main surface side, and the two-layer configuration corresponding to each of the conductive patterns Only for the step of forming the second routing circuit and the two-layered conductive pattern in the shape of the first and second strain sensing parts, the upper metal layer is removed by etching to remove the first and second conductive circuits. A step of obtaining a second strain sensing part, To provide a method of manufacturing a strain sensor for measuring.

In the strain sensor for multipoint measurement and the manufacturing method thereof according to the present invention, as described above, the plurality of strain sensitive portions and the routing circuits corresponding to the strain sensitive portions are provided on the same surface of the same base film. Therefore, no bonding is required for connection between the strain sensing part and the routing circuit. Accordingly, there is no conduction failure between the strain sensing part and the routing circuit due to the deviation at the time of bonding. Further, since the number of layers constituting the strain sensor can be reduced, the material cost and thus the manufacturing cost can be reduced.

The top view which looked at the sensor structure part of the strain sensor of 1st, 3rd and 4th embodiment of this invention from the 1st main surface side of the base film. Sectional drawing which attached the lead wire to the sensor structure part of the strain sensor of 1st, 3rd embodiment of this invention Sectional drawing which shows the lamination | stacking process of the strain sensor of 1st embodiment of this invention. Sectional drawing which shows the patterning process of the strain sensor of 1st embodiment of this invention. Sectional drawing which shows the strain sensitive part formation process of 1st embodiment of this invention. Sectional drawing which shows the cover layer formation process of the strain sensor of 1st embodiment of this invention. Sectional drawing which shows the terminal protective layer formation process of the strain sensor of 1st embodiment of this invention. Sectional drawing which shows the external shape processing process of the strain sensor of 1st, 3rd and 4th embodiment of this invention. The top view which shows another formation example (2nd Embodiment) of a routing circuit Sectional drawing which shows the lamination | stacking process of the strain sensor of 3rd Embodiment of this invention. Sectional drawing which shows the patterning process of the strain sensor of 3rd Embodiment of this invention. Sectional drawing which shows the routing circuit formation process of 3rd Embodiment of this invention. The top view which looked at the sensor structure part of the strain sensor of 4th Embodiment of this invention from the 2nd main surface side of the base film. Sectional drawing which attached the lead wire to the sensor structure part of the strain sensor of 4th Embodiment of this invention. Sectional drawing which shows the lamination | stacking process of the strain sensor of 4th Embodiment of this invention. Sectional drawing which shows the patterning process of the strain sensor of 4th Embodiment of this invention. Sectional drawing which shows the strain sensitive part formation process of 4th Embodiment of this invention. Sectional drawing which shows the cover layer formation process of the strain sensor of 4th Embodiment of this invention. Sectional drawing which shows the terminal protective layer formation process of the strain sensor of 4th Embodiment of this invention. A plan view showing an example of a sensor structure of a conventional strain sensor 20 is an exploded perspective view of a part of the sensor structure shown in FIG.

Hereinafter, embodiments according to the present invention will be described in more detail with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative positions, etc. of the parts and portions described in the embodiments of the present invention are not intended to limit the scope of the present invention only to those unless otherwise specified. This is just an illustrative example.

[First embodiment]
<Strain sensor>
As shown in FIGS. 1 and 2, the strain sensor 31 according to the present embodiment includes a base film 34 and a plurality of resistance-type strain sensing units 33 (hereinafter referred to as the first main surface 34 a) formed on the base film 34. , Simply referred to as a strain sensitive portion 33) and formed on the first main surface 34a of the base film 34 corresponding to each strain sensitive portion 33, and external

connection terminal portions

37b, 38b near the outer edge of the base film 34. And a sensor structure 36 having a two-layer routing circuit 37, 38. The entire sensor structure 36 is formed in a thin square plate shape, and the strain sensitive part 33 side of the base film 34 is in close contact with the structure. In FIG. 2, the sensor structure 36 is shown thick for the sake of illustration and explanation.

The base film 34 is made of an insulating material such as polyester (PET), polyimide amide (AI), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyimide (PI), polytetrafluoroethylene (PTFE). And a flexible film. The thickness of the base film 34 is appropriately selected according to the use of the strain sensor 31. Specifically, a base film 34 having a thickness of 1 μm to 300 μm can be employed. If the thickness exceeds the upper limit, strain sensitivity decreases. This is because exceeding the lower limit tends to cause breakage during strain.

The first main surface 34a of the base film 34 is provided with a plurality of strain sensing portions 33 as shown in FIGS. The strain sensitive portions 33 are arranged in a grid of 8 rows × 5 columns in plan view, and the length direction (axial direction) of the strain sensitive portions 33 is along the same direction.

The strain sensor 31 has a reduced cross-sectional area and an increased length due to the stretching of the metal constituting the main body 33c of each strain-sensitive part 33. The strain amount of the object to be measured is measured by utilizing the fact that the length is reduced as the area is increased and the resistance value is reduced as a result.

As can be seen from the partially enlarged view in FIG. 1, the main body 33 c of the strain sensing portion 33 is connected by a connecting portion in which a plurality of strip-like portions arranged in parallel at regular intervals extend in the width direction between ends. One resistor. That is, the main body 33c of the strain sensing unit 33 has a zigzag shape in which a single band-like body is folded back multiple times at regular intervals. Both ends of the bent main body 33c are connected to one end portions of two-layer routing circuits 37 and 38 via

wirings

33d and 33e. It is preferable that the width of the main body 33c of the strain sensing unit 33 is small so that the rate of change in resistance value can be easily detected. On the other hand, it is preferable that the wiring 33d of the strain sensing unit 33 has a large width so that the ratio of the resistance value of the wiring 33d to the resistance value of the entire strain sensing unit 33 is small. Further, the strain sensing unit 33 can be directly connected to the routing circuits 37 and 38 having a two-layer structure (not shown) by omitting the

wirings

33d and 33e.

The material of each strain sensing part 33 is not particularly limited as long as the main body 33c functions as a resistor. For example, platinum, aluminum, nickel, tungsten, iron, gold, silver, copper, palladium, chromium, copper nickel An alloy, a nickel chromium alloy, a copper manganese alloy, an iron chromium alloy, etc. can be mentioned. In particular, a copper nickel alloy, a nickel chromium alloy, a copper manganese alloy, and an iron chromium alloy are preferable from the viewpoint of resistance value and linear expansion coefficient. In the present invention, each strain sensing part 33 is formed directly on the base film 34 as shown in FIG. The strain sensitive part 33 can be formed by patterning a film made of the above material by an etching method. The thickness of each strain sensing part 33 is preferably 0.1 μm to 100 μm. This is because when the thickness exceeds the upper limit, the strain sensitivity decreases, and when the thickness exceeds the lower limit, the film is easily broken at the time of strain.

Further, as shown in FIGS. 1 and 2, a plurality of routing circuits 37 and 38 having a two-layer structure are provided on the first main surface 34a of the base film 34.

The number of the routing circuits 37 and 38 having the two-layer configuration is the same as the number of the strain sensing units 33, and each routing circuit 37 and 38 is associated with each strain sensing unit 33. ing. The materials of the lower layers 37L and 38L of the two-layer routing circuits 37 and 38 are the same as those of the strain sensing part 33, and the materials of the upper layers 37U and 38U are copper (Cu) and silver (Ag). Gold (Au), aluminum (Al), or the like can be used, but a conductor having a sufficiently smaller specific resistance than the strain sensing part 33 is appropriately selected. That is, the strain sensing part 33 and the lower layers 37L and 38L of the routing circuits 37 and 38 having a two-layer structure are continuously formed of the same material.
In the present invention, the routing circuits 37 and 38 are directly formed on the base film 34 as shown in FIG. The routing circuits 37 and 38 can be formed by patterning a metal film having a two-layer structure made of the above-described material by an etching method. The thickness of each routing circuit 37, 38 is preferably 0.1 μm to 100 μm. This is because when the thickness exceeds the upper limit, the strain sensitivity decreases, and when the thickness exceeds the lower limit, the film is easily broken at the time of strain.

The other end portions (external connection terminal portions) 37 b and 38 b of the routing circuits 37 and 38 are provided near one side of the base film 34. The routing circuits 37 and 38 extend on the first main surface of the base film 34 between the strain sensing part 33 and the external connection terminal part 37b, and between the strain sensing part 33 and the external connection terminal part 38b. Is provided. More specifically, as shown in FIG. 1, it is provided mainly extending along the length direction of the plurality of strip portions in the main body 33 c of each strain sensing portion 33. Further, the other end portions (external connection terminal portions) 37b and 38b of the routing circuits 37 and 38 are arranged in a bundle in several bundles in the longitudinal direction (vertical direction in FIG. 1) of the base film 34. Of course, all of them may be arranged in one bundle.

In this embodiment, the circuit 37, 38 is electrically connected to both ends of each strain sensing part 33 one by one. However, when the temperature effect is compensated by the three-wire connection method, Two routing circuits may be connected to one of both ends of the strain sensing unit 33 (not shown).

In the sensor structure 36 as described above, the plurality of strain sensing portions 33 and the routing circuits 37 and 38 corresponding to each strain sensing portion 33 are provided on the same surface of the same base film 34. Bonding is not required for connection between the strain sensing unit 33 and the routing circuits 37 and 38. Therefore, there is no conduction failure between the strain sensing part 33 and the routing circuits 37 and 38 due to the deviation at the time of bonding.
Further, since the number of layers constituting the strain sensor 31 can be reduced, the material cost and thus the manufacturing cost can be reduced.

Moreover, the above-described sensor structure 36 may further include other layers.
For example, as shown in FIG. 2, each strain sensing part 33 and each routing circuit 37, 38 are provided with the exception of the external

connection terminal parts

37b, 38b from the viewpoint of preventing deterioration due to oxidation, sulfurization, or migration (electric corrosion). You may make it cover with the insulating cover layer 63. FIG. As a method for forming the cover layer 63, a cover film such as a laminator or a hot press, or a printing method such as screen printing can be used.

When a cover film is bonded as a method for forming the cover layer 63, the same material as the base film 34 can be used for the cover film. Moreover, when printing as a formation method of the cover layer 63, it can form by apply | coating thermosetting resins, such as a urethane resin, a polyamide resin, an acrylic resin, and a polyimide resin, by predetermined thickness, and making it harden | cure, for example.

The terminal protective layer 45 may be formed so as to cover the other end portions (external connection terminal portions) 37b and 38b of the routing circuits 37 and 38. As a method for forming the terminal protective layer 45, nickel base gold plating, solder plating, or the like can be used.

The above is the structure of the sensor structure 36.

A lead wire 47 such as an FPC (Flexible Printed Circuit) connected to the measuring device is mounted directly or via the terminal protective layer 45 on the external

connection terminal portions

37b and 38b of the routing circuit.

In general, an FPC has a structure in which a plurality of wiring patterns are formed of gold-plated copper foil on a base film made of polyimide, and an unnecessary portion of each wiring pattern is covered with a coverlay made of polyimide. ing.

As a mounting method of the lead wire 47, for example, when the lead wire 47 is FPC, an anisotropic conductive film (ACF; Anisotropic Conductive Film) or an anisotropic conductive adhesive (ACA; Anisotropic Conductive Adhesive) 46 or the like is used. A thermocompression bonding method using an adhesive material or the like can be used.

The terminal protection layer 45 is provided from the viewpoint of preventing deterioration due to oxidation, sulfurization or migration of the external

connection terminal portions

37b and 38b of the routing circuit. The external

connection terminal portions

37b and 38b and the lead wire 47 are electrically connected. It has conductivity so that it can be connected. As a material of the terminal protective layer 45, for example, Ni base Au plating, solder plating, or the like can be used. A plating method is used to form the terminal protective layer 45 made of Ni base Au plating and solder plating. The plating method is also used to form the Ni layer that serves as the base of the Au plating.

When measuring strain of a structure, for example, a concrete structure of a tunnel or a steel structure of a bridge, by the strain sensor 31 of the present embodiment, out of both surfaces in the thickness direction of the base film 34 of the sensor structure 36, The surface on the strain sensing part 33 side is made to face the structure, and the sensor structure part 36 is brought into close contact with the structure by an adhesive interposed between the sensor structure part 36 and the structure.

A method for obtaining a strain sensor having the above configuration will be described in detail below.
<Manufacturing method of strain sensor>
The manufacturing method of the strain sensor for multipoint measurement of this embodiment is as follows.
(1) a step of laminating two metal layers on the first main surface of the base film;
(2) A two-layered conductive pattern in which a plurality of strain-sensitive parts are formed from a metal layer by an etching method, and a two-layered structure corresponding to the conductive pattern in the shape of the strain-sensitive parts. Forming a routing circuit;
(3) The step of removing the upper metal layer by an etching method and obtaining the strain sensitive part only for the conductive pattern having a two-layer structure in the shape of the strain sensitive part is provided.

In addition, in order to prevent deterioration due to oxidation, sulfurization or migration of the strain sensing part and the routing circuit,
(4) A step of forming an insulating cover layer on the first main surface of the base film, excluding the external connection terminal portion, covering the strain sensitive portion and the routing circuit;
(5) The method may further include a step of covering the external connection terminal portion of the routing circuit and forming a conductive terminal protective layer.

In addition, the manufacturing method of the strain sensor for multipoint measurement according to this embodiment includes the steps (1) to (3) or the steps (1) to (5).
(6) You may further provide the process of mounting a lead wire in the external connection terminal part of a routing circuit.

(1. Lamination process)
The laminating step is a step of sequentially laminating two metal layers, that is, a first metal layer 48 and a second metal layer 49 on the first main surface 34a of the base film 34 (see FIG. 3).

The base film 34 is a single wafer or a long one that supports the first metal layer 48 and the second metal layer 49. The material of the base film 34 is, for example, insulation such as polyester (PET), polyimide amide (AI), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyimide (PI), polytetrafluoroethylene (PTFE), etc. A film made of a sex material can be used. The substrate film 34 to be used may have a thickness of 1 μm to 100 μm.

The first metal layer 48 is for forming the strain sensing part 33 and the lower layers 37L, 38L of the routing circuits 37, 38. The material of the first metal layer 48 is not particularly limited as long as the main body 33c of the strain sensing part 33 functions as a resistor. For example, platinum, aluminum, nickel, tungsten, iron, gold, silver, copper , Palladium, chromium, copper nickel alloy, nickel chromium alloy, copper manganese alloy, iron chromium alloy and the like. In particular, a copper nickel alloy, a nickel chromium alloy, a copper manganese alloy, and an iron chromium alloy are preferable from the viewpoint of resistance value and linear expansion coefficient.
The method for forming the first metal layer 48 is not particularly limited. For example, the first metal layer 48 can be formed by bonding a metal foil by hot pressing, a vacuum deposition method, a sputtering method, an ion plating method, a plating method, or the like.

The second metal layer 49 is for forming the upper layers 37U, 38U of the routing circuits 37, 38. The material of the second metal layer 49 can be copper (Cu), silver (Ag), gold (Au), aluminum (Al), or the like, but a conductor having a sufficiently lower specific resistance than the first metal layer 48 is used. Select as appropriate.
The method for forming the second metal layer 49 is not particularly limited, and for example, as with the second metal layer 49, for example, metal foil bonding by hot pressing, vacuum deposition, sputtering, ion plating, plating method Etc. can be formed.

(2. Patterning process)
The patterning step is performed by etching using a two-layered conductive pattern having the shape of the plurality of strain sensitive portions 33 from the first metal layer 48 and the second metal layer 49 described above, and the strain sensitive portion 33. This is a step of forming the routing circuit 33 having a two-layer structure corresponding to each of the shaped conductive patterns (see FIG. 4).
For example, a resist film having a shape corresponding to the conductive pattern to be formed is stacked on the surfaces of the first metal layer 48 and the second metal layer 49, and the stacked body is immersed in an etching solution to form each conductive pattern. Thereafter, the resist film remaining on the patterned first metal layer 48 and second metal layer 49 is completely removed with a resist stripping solution to expose the entire surfaces of the first metal layer 48 and the second metal layer 49. .

In order to form the resist film in a shape corresponding to the conductive pattern, for example, a photosensitive resin composition such as a dry film resist or a liquid resist is applied, and an electron beam or light (ultraviolet light) is applied to the photosensitive resin film through a mask. Is exposed to a predetermined shape. Next, a portion unnecessary to be brought into contact with the developer is dissolved and removed. The photosensitive resin includes a negative type in which an exposed part is insoluble in a developer and a positive type in which an exposed part is soluble in a developer.
Moreover, in order to form a resist film in the shape according to a conductive pattern, printing methods, such as screen printing, can also be used.

(3. Strain sensitive part formation process)
In the strain sensitive part forming step, only the two-layered conductive pattern having the shape of the strain sensitive part 33 is removed by removing the upper metal layer, that is, the second metal layer 49 by an etching method. This is a step of obtaining 33 (see FIG. 5).
For example, after the routing circuit 33 obtained in the previous step is covered with a resist film, the second metal layer 49 is removed by immersion in an etching solution, and a conductive pattern consisting only of the first metal layer 48, that is, the strain sensing part 33. Get. Thereafter, the remaining resist film covering the routing circuit 33 is completely removed with a resist stripping solution, and the entire surface of the routing circuit 33 is exposed.
The formation of the resist film is the same as in the previous step.

By passing through the above steps, a plurality of strain sensitive portions 33 formed on the first main surface 34 a of the base film 34 and the first main surface 343 a of the base film 34 correspond to each strain sensitive portion 33. And two layers of routing circuits 37 and 38 having external

connection terminal portions

37b and 38b in the vicinity of the outer edge of the base film 34, and the lower layers 37L and 38L of the routing circuits 37 and 38 are subjected to strain reception. It is made of the same material as that of the sensing part 33, and the upper layers 37U and 38U of the routing circuits 37 and 38 are made of a material having a lower resistance than the strain sensing part 33.
In addition, when the base film 34 is elongate, the two or more said sensor structure parts 36 are formed continuously.

(4. Cover layer forming step)
The cover layer forming step is a step of covering the strain sensing part 33 and the routing circuits 37 and 38 with an insulating cover layer 63 except for the external

connection terminal parts

37b and 38b (see FIG. 6).
As a method for forming the cover layer 63, a cover film such as a laminator or a hot press, or a printing method such as screen printing can be used.

By passing through the above steps, the routing circuits 37 and 38 excluding the strain sensing part 33 and the external

connection terminal parts

37b and 38b can be protected from deterioration caused by oxidation, sulfurization or migration.

(5. Lead wire connection terminal protective layer forming step)
In the lead wire connection terminal protective layer forming step, the other end portions (external connection terminal portions) 37b and 38b of the routing circuits 37 and 38, that is, the portions that are not covered with the cover layer 63 and are exposed can be electrically connected to the lead wire 47. This is a step of covering with a new material to protect against deterioration caused by oxidation, sulfurization or migration (see FIG. 7).
As a method for forming the terminal protective layer 45, nickel base gold plating, solder plating, or the like can be used.

In addition, when the base film 34 is long, since two or more sensor structure portions 36 are continuously formed, the outer shape is further processed so as to be separated into individual sensor structure portions 36 (see FIG. 8). ).
A punching press, a laser cut, etc. can be used as a method of external shape processing.

(6. Lead wire mounting process)
The lead wire mounting step is a step of mounting the lead wire 47 on the external

connection terminal portions

37b and 38b of the routing circuits 37 and 38 with respect to the sensor structure portion 36 via the terminal protective layer 45 (see FIGS. 1 and 2). .
As a mounting method of the lead wire 47, for example, when the lead wire 47 is FPC, a thermocompression bonding method using a conductive adhesive substance such as an anisotropic conductive film or an anisotropic conductive adhesive 46 is used. it can.
Note that the lead wire 47 can be directly mounted on the external

connection terminal portions

37b and 38b by omitting the step of forming the terminal protective layer 45.

According to such a method for manufacturing a strain sensor, a plurality of strain sensitive portions and a routing circuit corresponding to each strain sensitive portion are provided on the same surface of the same base film, thereby obtaining a strain sensor. A bonding step is not required for connection between the strain sensing part and the routing circuit. Accordingly, there is no conduction failure between the strain sensing part and the routing circuit due to the deviation at the time of bonding.
In particular, in the patterning process of the conductive pattern on both surfaces of the base film, when exposure / development of the photosensitive resin is performed for forming the resist film for etching, the alignment accuracy between the strain sensitive portion and the routing circuit is higher.
Further, since the number of layers constituting the strain sensor can be reduced, the material cost and thus the manufacturing cost can be reduced.

[Second Embodiment]
This embodiment is the same as the first embodiment except that the formation directions of the routing circuits 37 and 38 are different, and a description of common parts is omitted.
That is, the routing circuits 37 and 38 of the invention according to the present embodiment are provided so as to extend along the width direction of the plurality of strips in the main body 33c of each strain sensing part 33, as shown in FIG. Yes. In this case, since the circuits 37 and 38 do not hinder the stretching / compression in the length direction of the metal constituting the band-shaped portion of each strain sensing portion 33, more accurate strain measurement can be performed.

[Third embodiment]
The present embodiment is the same as the first embodiment except that the method of forming the strain sensing part and the routing circuit is different in the method of manufacturing the strain sensor for multipoint measurement, and the description of the common parts is omitted.

<Manufacturing method of strain sensor>
Specifically, the manufacturing method of the strain sensor according to the present embodiment is as follows:
(1A) laminating one metal layer, that is, the first metal layer 48 on the first main surface 34a of the base film 34 (see FIG. 10);
(2A) A step of forming a plurality of strain sensitive portions 33 and conductive patterns in the shape of routing circuits 37 and 38 corresponding to each strain sensitive portion 33 from the first metal layer 48 by an etching method ( FIG. 11)
(3A) Steps for obtaining the routing circuits 37 and 38 having a two-layer structure by laminating another metal layer, that is, the second metal layer 49 only by using the printing method only for the conductive patterns in the shape of the routing circuits 37 and 38 (FIG. 12).
Further, at least one of the steps (4), (5) and (6) described in the first embodiment may be added to the above steps (1A) to (3A).

According to such a strain sensor manufacturing method, as in the first embodiment, a plurality of strain sensitive portions and routing circuits corresponding to the strain sensitive portions are provided on the same surface of the same base film. A strain sensor is obtained. Further, since the number of layers constituting the strain sensor can be reduced, the material cost and thus the manufacturing cost can be reduced.
Further, since etching is not performed in two stages, there is an advantage that the selection range of the etchant (etching solution) is widened.

[Fourth embodiment]
This embodiment is the same as the first embodiment except that the strain sensing part and the routing circuit are formed on both surfaces of the base film in the manufacturing method with the strain sensor for multipoint measurement. Description is omitted.

<Strain sensor>
As shown in FIGS. 1, 13, and 14, the strain sensor 31 of the present embodiment includes a base film 34 and a plurality of first strain sensing portions formed on the first main surface 34 a of the base film 34. 133 and a first main surface 34a of the base film 34 corresponding to each first strain sensing portion 133, and having a two-layer configuration having external

connection terminal portions

137b and 138b in the vicinity of the outer edge of the base film 34. A sensor structure 36 having first routing circuits 137 and 138 is provided.
The sensor structure 36 is formed on the second main surface 34b of the base film 34, and a plurality of second strain sensitive parts 233 having different axial directions from the first strain sensitive parts 133, and the base film. 34, a second routing circuit 237 having a two-layer structure formed on the second main surface 34b corresponding to each second strain sensing part 233 and having external

connection terminal parts

237b, 238b in the vicinity of the outer edge of the base film 34. 238, and a sensor structure portion 36 having 238.

The sensor structure part 36 is configured in a thin rectangular plate shape as a whole, and the first strain sensitive part 133 side or the second strain sensitive part 233 side of the base film 34 is in close contact with the structure. In FIG. 14, the sensor structure 36 is shown thick for convenience of illustration and description.

As shown in FIG. 1 and FIG. 14, the first strain sensing unit 133 is the same as the strain sensing unit 33 of the first embodiment, and is arranged in a grid of 8 rows × 5 columns in plan view. In both cases, the length direction (axial direction) of the strain sensing part 133 is along the same direction.

As shown in FIGS. 13 and 14, the second strain sensing unit 233 is the same as the strain sensing unit 33 of the first embodiment, but has a grid shape of 3 rows × 8 columns in plan view. In any case, the length direction (axial direction) of the strain sensing unit 233 is orthogonal to the length direction (axial direction) of the strain sensing unit 133.

In this way, by providing a plurality of strain sensitive portions on both sides of the base film 34 and changing the direction of the strain sensitive portions on the front and back, it is possible to measure the strain amount in a plurality of directions in the object to be measured. it can.

As shown in FIGS. 1 and 14, the number of the first routing circuits 137 and 138 is the same as the number of the corresponding first strain sensing units 133, and the routing circuits are connected to the individual strain sensing units 133. 137 and 138 are associated one by one. The first routing circuits 137 and 138 are the same as the routing circuits 37 and 38 of the first embodiment. As shown in FIG. 1, the lengths of the plurality of strip portions in the main body 233c of each strain sensing portion 133 are mainly used. It is provided extending along the direction.

As shown in FIGS. 13 and 14, the number of

second routing circuits

237 and 238 is the same as the number of the corresponding second strain sensing units 233, and each strain sensing unit 233 includes The

routing circuits

237 and 238 are associated one by one. The

second routing circuits

237 and 238 are the same as the routing circuits 37 and 38 of the first embodiment. However, in the example shown in FIG. 13, the lengths of a plurality of strip portions in the main body 133c of each strain sensing portion 233 are mainly used. It extends along a direction orthogonal to the vertical direction. Therefore, the external

connection terminal portions

237b and 238b of the

second routing circuits

237 and 238 can be aligned on one side when the external

connection terminal portions

137b and 138b of the first routing circuits 137 and 138 are provided.
Note that the extending direction of the

second routing circuits

237 and 238 shown in FIG. 13 is an example, and, like the routing circuits 37 and 38 of the first embodiment, a plurality of strip-like portions in the main body 233c of each strain sensing portion 233 are used. It can also be provided extending along the length direction.

A method for obtaining a strain sensor having the above configuration will be described below.
<Manufacturing method of strain sensor>
The manufacturing method of the strain sensor for multipoint measurement of this embodiment is as follows.
(1B) Step of laminating two metal layers, that is, the first metal layer 48 and the second metal layer 49 in this order on the first main surface 34a and the second main surface 34b of the base film 34 ( FIG. 15)
(2B) a conductive pattern having a two-layer configuration in which the first metal layer 48 and the second metal layer 49 on the first main surface 34a side are formed into a plurality of the first strain sensing portions 133 by the etching method; The first routing circuits 137 and 138 having a two-layer structure corresponding to the respective conductive patterns are formed, and at the same time, a plurality of the second strain receiving circuits are formed from the first metal layer 48 and the second metal layer 49 on the second main surface 34b side. Forming a conductive pattern having a two-layer configuration in the shape of the sensitive portion 233 and the

second routing circuits

237 and 238 having a two-layer configuration corresponding to the conductive pattern, respectively (see FIG. 16);
(2B) The upper metal layer, that is, the second metal layer 49 is removed by an etching method only for the two-layered conductive pattern in the shape of the first and second

strain sensing parts

133, 233, and the second metal layer 49 is removed. And a step of obtaining the first and second strain sensing parts 133, 233 (see FIG. 17).

In addition, in order to prevent deterioration due to oxidation, sulfurization or migration of the strain sensing part and the routing circuit,
(4B) The first main surface 34a of the base film except for the external

connection terminal portions

137b and 138b, covers the first strain sensing portion 133 and the first routing circuits 137 and 138, and has an insulating first. 1 cover layer 43 is formed, and on the other hand, the second main surface 34b is excluded from the external

connection terminal portions

237b and 238b, and covers the second strain sensing portion 233 and the

second routing circuits

237 and 238. Forming the second cover layer 44 (see FIG. 18),
(5B) A conductive first terminal protective layer 64 is formed so as to cover the external

connection terminal portions

137b and 138b of the first routing circuits 137 and 138, while the external connection of the

second routing circuits

237 and 238 is performed. A step of covering the

terminal portions

237b and 238b and forming the conductive second terminal protective layer 65 (see FIG. 19).

In addition, the method for manufacturing a strain sensor for multipoint measurement according to the present embodiment includes steps (1B) to (3B) or steps (1B) to (5B).
(6B) The method may further include a step of mounting the lead wire 47 on the external

connection terminal portions

137b, 138b, 237b, 238b of the first and

second routing circuits

137, 138, 237, 238 (see FIG. 14). .

According to such a strain sensor manufacturing method, as in the first embodiment, a plurality of strain sensitive portions and routing circuits corresponding to the strain sensitive portions are provided on the same surface of the same base film. A strain sensor is obtained. Further, since the number of layers constituting the strain sensor can be reduced, the material cost and thus the manufacturing cost can be reduced.
In addition, as described above, a plurality of strain sensitive portions are provided on both surfaces of the base film 34, and the direction of the strain sensitive portions is changed between the front and back sides, thereby measuring the strain amount in a plurality of directions in the measured object. can do.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

In the sensor structure portion 36 constituting the strain sensor 31 of the above embodiment, as shown in FIGS. 1 and 13, all the strain sensing portions 33 align the above-described sensing directions in one direction within the same plane. However, the present invention is not limited to this. For example, two strain sensitive sections 33 in two directions may be mixed at right angles in the same plane, and further, two strain sensitive sections 33 in two right angles and 45 degrees may be mixed (not shown). ) By changing the direction of the plurality of strain sensing sections 33, the amount of strain in a plurality of directions in the object to be measured can be measured.

In the strain sensor 31 of the above embodiment, the sensor structure 36 is connected to an external measuring instrument using the lead wire 47, but the external connection method is not limited to this. For example, a transmission device may be provided in the sensor structure 36 and the measured output value may be wirelessly transmitted to the measuring instrument.

DESCRIPTION OF

SYMBOLS

1,31 Strain sensor 2 Flexible board 3 Strain gauge 4 Gauge base 5 Cover film 6, 36 Sensor structure part 7 1st layer board 8 2nd layer board |

substrates

13, 33 Strain sensitive part 133 1st strain sensitive part 233 1st Strain sensitive parts 14a, 14b Tab (conductor connection part)
18, 19, 20, 37, 38 Routing circuits 137, 138

First routing circuits

237, 238 Second routing circuit 2 Through hole 23 Solder (conductor member)
33c, 133c, 233c

Main body

33d, 33e, 133d, 133e, 233d, 233e Wiring 34 Base film 34a First main surface 34b Second

main surface

37b, 38b, 137b, 138b, 237b, 238b External connection terminal 43 first Cover layer 44 Second cover layer 45 Terminal protective layer 46 Anisotropic conductive adhesive 47 Lead wire 48 First metal layer 49 Second metal layer 63 Cover layer 64 First terminal protective layer 65 Second terminal protective layer

Claims

A base film;
A plurality of strain sensitive parts formed on the first main surface of the base film;
A two-layer routing circuit formed on the first main surface of the base film corresponding to each strain-sensitive part and having an external connection terminal part near the outer edge of the base film;
The lower layer of the routing circuit is made of the same material as the strain sensing part,
A strain sensor for multipoint measurement, wherein an upper layer of the routing circuit is made of a material having a resistance lower than that of the strain sensing part.
An insulating cover layer formed on the first main surface of the base film, excluding the external connection terminal portion, covering the strain sensitive portion and the routing circuit;
The strain sensor for multipoint measurement according to claim 1, further comprising a conductive terminal protective layer formed to cover the external connection terminal portion of the routing circuit.
A base film;
A plurality of first strain sensing parts formed on the first main surface of the base film;
A first routing circuit having a two-layer structure formed on the first main surface of the base film in correspondence with each of the first strain sensitive parts and having an external connection terminal near the outer edge of the base film;
A plurality of second strain sensitive portions formed on the second main surface of the base film and having different axial directions from the first strain sensitive portions,
A second routing circuit having a two-layer structure formed on the second main surface of the base film in correspondence with each of the second strain sensing parts and having an external connection terminal near the outer edge of the base film. Prepared,
The lower layer of the first and second routing circuits is made of the same material as the first and second strain sensing parts,
A strain sensor for multipoint measurement, wherein an upper layer of the first and second routing circuits is made of a material having a resistance lower than that of the first and second strain sensing units.
An insulating first cover layer formed on the first main surface of the base film, excluding the external connection terminal portion, covering the first strain sensitive portion and the first routing circuit,
A conductive first terminal protective layer formed to cover the external connection terminal portion of the first routing circuit;
An insulating second cover layer formed on the second main surface of the base film, excluding the external connection terminal portion, covering the second strain sensitive portion and the second routing circuit;
The strain sensor for multipoint measurement according to claim 3, further comprising a conductive second terminal protective layer formed to cover the external connection terminal portion of the second routing circuit.
The strain sensor for multipoint measurement according to any one of claims 1 to 4, further comprising a lead wire mounted on the external connection terminal portion.
A method for manufacturing a strain sensor according to claim 1, comprising:
Laminating two metal layers on the first main surface of the base film;
Etching is used to form a two-layered conductive pattern in the shape of a plurality of strain-sensitive parts from the metal layer, and the two-layered structure corresponding to the conductive pattern in the shape of the strain-sensitive parts. Forming a circuit;
A strain sensor for multipoint measurement comprising a step of removing the upper metal layer by an etching method to obtain the strain sensitive part only for a conductive pattern having a two-layer structure having the shape of the strain sensitive part. Production method.
A method for manufacturing a strain sensor according to claim 1, comprising:
Laminating one metal layer on the first main surface of the base film;
Forming a plurality of strain sensitive portions from the metal layer and an electrically conductive pattern in the shape of the routing circuit corresponding to each strain sensitive portion by an etching method;
A method of manufacturing a strain sensor for multipoint measurement comprising: only a conductive pattern having a shape of the routing circuit, and obtaining a routing circuit having a two-layer structure by laminating another metal layer by a printing method.
A method of manufacturing a strain sensor according to claim 3,
Laminating two metal layers on each of the first main surface and the second main surface of the base film;
A two-layered conductive pattern in which a plurality of first strain sensitive portions are formed from a metal layer on the first main surface side by an etching method, and the first routing of a two-layer configuration corresponding to each of the conductive patterns. Forming a circuit, and simultaneously forming a plurality of second strain sensing portions in the shape of a plurality of the second strain sensing portions from the metal layer on the second main surface side, and the second layer configuration corresponding to each of the conductive patterns. Forming a two routing circuit;
Only for the two-layered conductive pattern in the shape of the first and second strain sensitive portions, the step of removing the upper metal layer by an etching method to obtain the first and second strain sensitive portions; The manufacturing method of the strain sensor for multipoint measurement provided with.