WO2022163324A1 - Strain sensor - Google Patents

Strain sensor Download PDF

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Publication number
WO2022163324A1
WO2022163324A1 PCT/JP2022/000343 JP2022000343W WO2022163324A1 WO 2022163324 A1 WO2022163324 A1 WO 2022163324A1 JP 2022000343 W JP2022000343 W JP 2022000343W WO 2022163324 A1 WO2022163324 A1 WO 2022163324A1
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WO
WIPO (PCT)
Prior art keywords
film
strain
strain sensor
detection element
metal film
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PCT/JP2022/000343
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French (fr)
Japanese (ja)
Inventor
位 小野
誠 北爪
彩 小野
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ミネベアミツミ株式会社
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Publication of WO2022163324A1 publication Critical patent/WO2022163324A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge

Definitions

  • the present invention relates to strain sensors.
  • a strain sensor that has a resistor on a flexible base material, is attached to an object to be measured, and detects the characteristics of the object to be measured.
  • a sensing part having a base part made of an insulating material, a pattern part made of a resistor provided on one side of the base part, an insulator layer, and one side of the insulator layer and a thin-film intermediate member provided on the other side of the base portion of the sensing portion and provided with a shield layer formed of a conductor and arranged to face the other surface side of the base portion in the sensing portion.
  • the present invention has been made in view of the above points, and an object of the present invention is to provide a strain sensor capable of reducing the influence of disturbance noise while suppressing an increase in thickness.
  • This strain sensor (1) includes a film substrate (10), a strain detection element (20) formed on the upper surface (10a) of the film substrate (10), and a plane view, the strain detection element (20) is separated from the and a shield film (30) surrounding the periphery of the strain detection element (20).
  • FIG. 1 is a plan view illustrating a strain sensor according to a first embodiment
  • FIG. 1 is a cross-sectional view (part 1) illustrating a strain sensor according to a first embodiment
  • FIG. FIG. 2 is a cross-sectional view (part 2) illustrating the strain sensor according to the first embodiment
  • It is a figure which shows the usage example of the strain sensor which concerns on 1st Embodiment.
  • It is a figure which shows the connection example of the strain sensor which concerns on 1st Embodiment.
  • FIG. 5 is a cross-sectional view illustrating a strain sensor according to a comparative example
  • FIG. 5 is a diagram showing a connection example of a strain sensor according to a comparative example;
  • FIG. 5 is a diagram showing an example of measurement of output voltage of a strain sensor according to a comparative example; It is a figure which shows the example of a measurement of the output voltage of the distortion sensor which concerns on 1st Embodiment.
  • FIG. 7 is a cross-sectional view illustrating a strain sensor according to Modification 1 of the first embodiment;
  • FIG. 1 is a plan view illustrating a strain sensor according to a first embodiment
  • FIG. FIG. 2 is a cross-sectional view illustrating the strain sensor according to the first embodiment, showing a cross section along line AA in FIG.
  • FIG. 3 is a cross-sectional view illustrating the strain sensor according to the first embodiment, showing a cross section along line BB in FIG. 1 to 3, the strain sensor 1 has a film substrate 10, a strain detecting element 20, a shield film 30, terminals 40A, 40B and 40C, and a cover film 50.
  • the side of the film substrate 10 provided with the strain detection element 20 is the upper side or one side, and the side without the strain detection element 20 is the lower side or the other side. and also, the surface on which the strain detection element 20 of each part is provided is defined as one surface or upper surface, and the surface on which the distortion detection element 20 is not provided is defined as the other surface or lower surface.
  • the strain sensor 1 can be used upside down or arranged at any angle.
  • the term "planar view” refers to viewing an object from the direction normal to the upper surface 10a of the film substrate 10
  • the term “planar shape” refers to the shape of the object viewed from the direction normal to the upper surface 10a of the film substrate 10.
  • the film substrate 10 is a member that serves as a base layer for forming the strain detection element 20 and the like, and has flexibility.
  • the film thickness of the film substrate 10 is not particularly limited and can be appropriately selected according to the purpose.
  • the vertical length and horizontal length of the film substrate 10 in a plan view are not particularly limited and can be appropriately selected according to the purpose, but each can be, for example, about 1 mm to 5 mm.
  • the film substrate 10 is made of insulating resin such as PI (polyimide) resin, for example.
  • the film substrate 10 may be made of an insulating resin such as epoxy resin, PEEK (polyetheretherketone) resin, PEN (polyethylene naphthalate) resin, PET (polyethylene terephthalate) resin, PPS (polyphenylene sulfide) resin, or polyolefin resin. good.
  • the strain detection element 20 is a thin film formed in a predetermined pattern on the upper surface 10a of the film substrate 10, and is a sensing part that undergoes a change in resistance when subjected to strain.
  • the strain detection element 20 may be formed directly on the top surface 10a of the film substrate 10, or may be formed on the top surface 10a of the film substrate 10 via another layer.
  • the distortion detection element 20 is shown with a pear-skin pattern for the sake of convenience.
  • a plurality of elongated portions are arranged at predetermined intervals with their longitudinal directions directed in the same direction (the direction of line AA in FIG. 1), and the ends of adjacent elongated portions are staggered. It is a structure that is connected and folded in a zigzag as a whole.
  • the longitudinal direction of the elongated portions is the grid direction, and the direction perpendicular to the grid direction is the grid width direction.
  • the strain detection element 20 is, for example, a conductive metal film containing Cr and CrN.
  • the film thickness of the strain detection element 20 can be, for example, about 100 nm to 500 nm.
  • the width of the strain detection element 20 can be, for example, about 50 ⁇ m to 300 ⁇ m.
  • the shield film 30 is a conductive metal film formed on the upper surface 10a of the film substrate 10 in a predetermined pattern.
  • the shield film 30 may be formed directly on the upper surface 10a of the film substrate 10, or may be formed on the upper surface 10a of the film substrate 10 via another layer.
  • the shield film 30 is arranged so as to surround the distortion detection element 20 while being separated from the distortion detection element 20 in plan view.
  • the shield film 30 is not electrically connected to the strain sensing element 20 .
  • the shield film 30 is shown with a pear-skin pattern different from that of the strain detection element 20 for the sake of convenience.
  • the shield film 30 is made of the same material as the strain detection element 20, for example. That is, if the strain sensing element 20 is a conductive metal film containing Cr and CrN, the shield film 30 is also a conductive metal film containing Cr and CrN and has the same thickness as the strain sensing element 20 . In this case, the manufacturing process can be simplified by forming the shield film 30 in the same process as the strain detection element 20 .
  • the shield film 30 is connected to GND via the terminal 40C to generate a shield effect, absorb disturbance noise, and reduce the disturbance noise superimposed on the strain detection element 20.
  • the shield film 30 may be made of a material with lower impedance than the strain detection element 20 .
  • the strain sensing element 20 is a conductive metal film containing Cr and CrN
  • the shield film 30 can be a conductive metal film containing Ni, Al, Cu, or the like.
  • the distance d between the shield film 30 and the strain detection element 20 is preferably 5 ⁇ m or more from the viewpoint of processing accuracy. Further, when the distance d is less than 5 ⁇ m, the line capacitance between the shield film 30 and the strain detection element 20 becomes large, and the noise absorbed by the shield film 30 due to capacitive coupling short-circuit easily propagates to the strain detection element 20. It is not preferable because Moreover, the distance d between the shield film 30 and the strain detection element 20 is preferably 20 ⁇ m or less from the viewpoint of obtaining a sufficient shield effect by the shield film 30 absorbing disturbance noise. It is more preferable that the distance d between the shield film 30 and the strain detection element 20 is 10 ⁇ m or less in that a greater shield effect can be obtained.
  • the terminals 40A and 40B extend from both ends of the strain detection element 20 and are formed in a substantially rectangular shape wider than the strain detection element 20 in plan view.
  • the terminals 40A and 40B are a pair of electrodes for outputting to the outside the change in the resistance value of the strain detecting element 20 caused by strain, and for example, lead wires for external connection (for example, twisted wires) are joined. .
  • the terminals 40A and 40B have, for example, a laminated structure in which a plurality of metal films are laminated.
  • the terminal 40A has a metal film 41 extending from both ends of the strain sensing element 20 and a metal film 45 formed on the upper surface of the metal film 41. ing.
  • the metal film 41 and the strain detecting element 20 are given different reference numerals for the sake of convenience, the metal film 41 and the strain detecting element 20 are integrally formed from the same material in the same process.
  • the metal film 45 can be formed, for example, from a metal having better solderability than the metal film 41.
  • the material of the metal film 42 is, for example, Cu, Cu alloy, Ni, or Ni alloy.
  • the thickness of the metal film 42 is, for example, 4 ⁇ m or more and 30 ⁇ m or less.
  • a material having better solder wettability than the metal film 45 may be laminated on the upper surface of the metal film 45 .
  • the material of the metal film 42 is Cu, Cu alloy, Ni, or Ni alloy
  • Au (gold) can be used as the material of the stacked metal film.
  • the terminal 40C is electrically connected to the shield film 30.
  • the terminal 40C is an electrode for connecting the shield film 30 to GND outside the strain sensor 1, and is connected to, for example, a lead wire (for example, twisted wire) for external connection.
  • the terminal 40C is arranged at a position sandwiched between the terminals 40A and 40B in plan view, but the terminal 40C may be arranged at an arbitrary position. Also, a plurality of terminals electrically connected to the shield film 30 may be arranged.
  • the terminal 40C has, for example, a laminated structure in which a plurality of metal films are laminated. Specifically, in the examples of FIGS. 1 and 3, the terminal 40C has a metal film 42 extending from the shield film 30 and a metal film 45 formed on the upper surface of the metal film 42. As shown in FIG. Although the metal film 42 and the shield film 30 are denoted by different symbols for the sake of convenience, they are integrally formed of the same material in the same process as the shield film 30 . In other words, the shield film 30 positioned below the metal film 45 is called the metal film 42 for convenience. The metal film 45 is as described for the terminals 40A and 40B.
  • the cover film 50 is a protective film that covers the strain detection element 20 and the shield film 30 and exposes at least a portion of the upper surface of each of the terminals 40A, 40B, and 40C. At least a portion of the upper surface of the terminal 40A is exposed from the opening 50A of the cover film 50, at least a portion of the upper surface of the terminal 40B is exposed from the opening 50B of the cover film 50, and the terminal 40C is exposed from the opening 50C of the cover film 50. at least a portion of the top surface of the is exposed.
  • the cover film 50 can be formed from an insulating resin (organic film) such as PI resin, epoxy resin, PEEK resin, PEN resin, PET resin, PPS resin, composite resin (for example, silicone resin, polyolefin resin).
  • the cover film 50 may be formed from an inorganic film such as a silicon oxide film ( SiO2 ), a glass film, a silicon nitride film (SiN), or the like.
  • the cover film 50 By providing the cover film 50, it is possible to prevent the strain detection element 20 and the shield film 30 from being mechanically damaged. Also, by providing the cover film 50, the strain detecting element 20 and the shield film 30 can be protected from moisture and the like.
  • the strain detection element 20 and the shield film 30 are made of the same material.
  • the film substrate 10 is prepared, and a metal film (referred to as metal film A for convenience) is formed on the entire upper surface 10 a of the film substrate 10 .
  • the metal film A is a film that is finally patterned to become the strain sensing element 20 and the shield film 30 (including the metal films 41 and 42). Therefore, the material and thickness of the metal film A are the same as those of the strain detecting element 20 and the shield film 30 described above.
  • the metal film A can be formed by sputtering, for example.
  • the metal film A is patterned by photolithography to form the planar strain detection element 20 and the shield film 30 (including the metal films 41 and 42) shown in FIG. Specifically, a resist is applied on the metal film A, and the strain detecting element 20 and the shield film 30 (including the metal films 41 and 42) are patterned by photolithography and etching. After the patterning is finished, the resist is removed.
  • a resist is applied to the entire upper surface 10a of the film substrate 10 so as to cover the patterned strain sensing element 20 and the shield film 30 (including the metal films 41 and 42). Then, the resist is patterned by photolithography and etching, and openings are formed so as to expose the portions that will become the terminals 40A, 40B, and 40C. Then, the terminals 40A, 40B, and 40C are formed by depositing a metal film 45 in each opening by an electrolytic plating method, an electroless plating method, or the like. After forming the terminals 40A, 40B, and 40C, the resist is removed.
  • a cover film 50 is formed over the entire upper surface 10a of the film substrate 10 so as to cover the patterned strain sensing element 20 and the shield film 30 (including the terminals 40A, 40B, and 40C). Etching forms openings 50A, 50B, and 50C. At least part of the upper surface of the terminal 40A is exposed through the opening 50A, at least part of the upper surface of the terminal 40B is exposed through the opening 50B of the cover film 50, and at least the upper surface of the terminal 40C is exposed through the opening 50C of the cover film 50. partly exposed.
  • the strain sensor 1 is completed.
  • FIG. 4 is a diagram showing a usage example of the strain sensor according to the first embodiment.
  • the strain sensor 1 is adhered to the strain body 120 via the adhesive layer 110 .
  • the lower surface of the film substrate 10 of the strain sensor 1 is adhered to the upper surface of the strain body 120 via the adhesive layer 110 .
  • the adhesive layer 110 is not particularly limited as long as it has a function of adhering the strain sensor 1 and the strain generating body 120, and can be appropriately selected depending on the purpose. Examples include epoxy resin, modified epoxy resin, and silicone resin. , modified silicone resin, urethane resin, modified urethane resin, and the like can be used.
  • the strain-generating body 120 is an object that is made of, for example, a metal such as Fe, SUS (stainless steel), or Al, or a resin such as PEEK, and that deforms (generates strain) according to applied force.
  • the strain sensor 1 can detect strain occurring in the strain generating element 120 as a change in the resistance value of the strain detecting element 20 .
  • connection member 140 The upper surface of each of the terminals 40A, 40B, and 40C exposed from the cover film 50 is electrically connected to the connection member 140 via the bonding material 130.
  • the bonding material 130 is, for example, solder or conductive paste.
  • the connection member 140 is, for example, a lead wire, a flexible printed wiring board, or the like. Note that the strain sensor 1 with the bonding material 130 and the connection member 140 attached thereto may be distributed on the market.
  • FIG. 5 is a diagram showing a connection example of strain sensors according to the first embodiment.
  • the strain sensor 1 is connected to the measuring section 200 arranged outside the strain sensor 1 via the connection member 140 .
  • the measuring section 200 has a bridge circuit.
  • the bridge circuit has three sides composed of fixed resistors R1, R2, and R3, and the other side connected to the strain detecting element 20 via the connection member 140 and the terminals 40A and 40B.
  • a DC voltage VDD is applied between a pair of diagonal points of the bridge circuit.
  • GND of the bridge circuit is connected to the shield film 30 via the connecting member 140 and the terminal 40C.
  • analog voltages V1 and V2 corresponding to the strain of the strain detecting element 20 are output between the other pair of diagonal points of the bridge circuit.
  • the shield film 30 is connected to the GND of the bridge circuit to produce a shield effect, absorb disturbance noise, and reduce disturbance noise superimposed on the strain detection element 20 . Therefore, voltages V1 and V2 with little noise are obtained.
  • FIG. 6 is a cross-sectional view illustrating a strain sensor according to a comparative example, showing a cross section corresponding to line AA in FIG.
  • a strain sensor 1X shown in FIG. 6 differs from the strain sensor 1 in that it does not have a shield film 30 and terminals 40C.
  • the strain sensor 1X is adhered to the strain body 120 via the adhesive layer 110, as in FIG. Moreover, in the strain sensor 1X shown in FIG. 6, similarly to FIG. . Further, as shown in FIG. 7, the strain sensor 1X is connected via a connecting member 140 to a measuring section 200 arranged outside the strain sensor 1X.
  • FIG. 8 is a diagram showing a measurement example of the output voltage of the strain sensor according to the comparative example.
  • the output voltage of the strain sensor 1X is obtained by amplifying the voltage between V1 and V2 in FIG.
  • FIG. 9 is a diagram showing a measurement example of the output voltage of the strain sensor according to the first embodiment.
  • the output voltage of the strain sensor 1 is obtained by amplifying the voltage between V1 and V2 in FIG. 8 and 9 are measured under the same conditions (same environment).
  • the X-axis (measurement time) and Y-axis (output voltage) scales in FIG. 8 match the X-axis (measurement time) and Y-axis (output voltage) scales in FIG.
  • the disturbance noise superimposed on the output voltage is significantly reduced as compared with the strain sensor 1X according to the comparative example.
  • the shield film 30 is provided so as to surround the distortion detection element 20 while being separated from the distortion detection element 20 in a plan view, and is connected to the GND of the bridge circuit so that the shield film 30 can block disturbance noise. Disturbance noise that is absorbed and superimposed on the strain detection element 20 can be reduced. As a result, the S/N ratio is improved and an output voltage with little noise is obtained, so the detection sensitivity of the strain sensor 1 is improved.
  • the strain detection element 20 is less susceptible to disturbance noise, the detection sensitivity of the strain sensor 1 is stabilized. In addition, since the strain detection element 20 is less susceptible to disturbance noise, the distance between the terminals 40A and 40B and the bridge circuit can be increased, thereby improving the degree of freedom in arranging the strain sensor 1 and/or the bridge circuit.
  • the shield film 30 is formed on the upper surface 10a of the film substrate 10 in the same manner as the strain detecting element 20, so an increase in the thickness of the strain sensor 1 can be suppressed. That is, the strain sensor 1 can reduce the influence of disturbance noise while suppressing an increase in thickness.
  • Modification 1 of the first embodiment shows an example in which the shield film has a laminated structure.
  • the description of the same components as those of the already described embodiment may be omitted.
  • FIG. 10 is a cross-sectional view illustrating a strain sensor according to Modification 1 of the first embodiment, showing a cross section corresponding to line AA in FIG.
  • the strain sensor 1A differs from the strain sensor 1 (see FIG. 2, etc.) in that the shield film 30 is replaced with a shield film 30A.
  • the shield film 30A has a metal film 31 and a metal film 35 formed on the upper surface of the metal film 31 .
  • the metal film 31 is the same layer as the shield film 30 of the strain sensor 1, although it is denoted by a different symbol for the sake of convenience.
  • the metal film 35 is made of a material whose impedance is lower than that of the metal film 31 .
  • the metal film 35 can be integrally formed with the same material in the same step as the metal film 45, for example.
  • the metal film 31 is a metal film containing Cr
  • the metal film 35 is a metal film containing Cu.
  • the shield film 30A is formed, for example, as follows.
  • the second openings to expose the metal film 31 are also formed at the same time.
  • the terminals 40A, 40B, and 40C are formed by depositing the metal film 45 in each opening by an electrolytic plating method, an electroless plating method, or the like, the metal film 31 exposed in the second opening is simultaneously formed.
  • a shield film 30A is formed by depositing a metal film 35 on the substrate.
  • the ability of the shield film 30A to absorb disturbance noise can be improved.
  • the strain sensing element 20 is a conductive metal film containing Cr and CrN
  • the impedance is relatively high. Therefore, by laminating a metal film 35 formed of Cu or the like having an impedance lower than that of the metal film 31 on the metal film 31, the impedance of the shield film 30A is lowered and the disturbance noise absorbability of the shield film 30A is improved. improves.
  • the shield film 30A with excellent disturbance noise absorption can be formed without adding a new process.

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  • General Physics & Mathematics (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

This strain sensor comprises a film substrate, a strain detection element formed on an upper surface of the film substrate, and a shield film surrounding the periphery of the strain detection element with a space from the strain detection element in a plan view.

Description

歪みセンサstrain sensor
　本発明は、歪みセンサに関する。 The present invention relates to strain sensors.
　可撓性を有する基材上に抵抗体を備え、測定対象物に貼り付けて、測定対象物の特性を検出する歪みセンサが知られている。例えば、絶縁性の材料によって形成されたベース部と、このベース部の一面側に設けられた抵抗体からなるパターン部とを備えた受感部と、絶縁体層と、この絶縁体層の一面側に設けられるとともに、受感部におけるベース部の他面側と対向して配設される導電体で形成されたシールド層とを備えた薄膜状の中間部材とを備えた、歪みセンサが挙げられる（例えば、特許文献１参照）。 A strain sensor is known that has a resistor on a flexible base material, is attached to an object to be measured, and detects the characteristics of the object to be measured. For example, a sensing part having a base part made of an insulating material, a pattern part made of a resistor provided on one side of the base part, an insulator layer, and one side of the insulator layer and a thin-film intermediate member provided on the other side of the base portion of the sensing portion and provided with a shield layer formed of a conductor and arranged to face the other surface side of the base portion in the sensing portion. (See Patent Document 1, for example).
特開２０１４－８５２５９号公報JP 2014-85259 A
　しかしながら、特許文献１に記載の歪みセンサは、外乱ノイズの影響を低減できるものの、構造が複雑であるため製造工程が増加すると共に、歪みセンサ全体が厚くなる。 However, although the strain sensor described in Patent Document 1 can reduce the influence of disturbance noise, the structure is complicated, so the number of manufacturing steps increases and the thickness of the strain sensor as a whole increases.
　本発明は、上記の点に鑑みてなされたもので、厚さの増加を抑えつつ外乱ノイズの影響を低減可能な歪みセンサを提供することを目的とする。 The present invention has been made in view of the above points, and an object of the present invention is to provide a strain sensor capable of reducing the influence of disturbance noise while suppressing an increase in thickness.
　本歪みセンサ（１）は、フィルム基板（１０）と、前記フィルム基板（１０）の上面（１０ａ）に形成された歪み検出素子（２０）と、平面視、前記歪み検出素子（２０）と離間して前記歪み検出素子（２０）の周辺を囲うシールド膜（３０）と、を有する。 This strain sensor (1) includes a film substrate (10), a strain detection element (20) formed on the upper surface (10a) of the film substrate (10), and a plane view, the strain detection element (20) is separated from the and a shield film (30) surrounding the periphery of the strain detection element (20).
　なお、上記括弧内の参照符号は、理解を容易にするために付したものであり、一例にすぎず、図示の態様に限定されるものではない。 It should be noted that the reference numerals in parentheses above are attached for easy understanding, and are merely examples, and are not limited to the illustrated embodiment.
　開示の技術によれば、厚さの増加を抑えつつ外乱ノイズの影響を低減可能な歪みセンサを提供できる。 According to the disclosed technique, it is possible to provide a strain sensor capable of reducing the influence of disturbance noise while suppressing an increase in thickness.
第１実施形態に係る歪みセンサを例示する平面図である。1 is a plan view illustrating a strain sensor according to a first embodiment; FIG. 第１実施形態に係る歪みセンサを例示する断面図（その１）である。1 is a cross-sectional view (part 1) illustrating a strain sensor according to a first embodiment; FIG. 第１実施形態に係る歪みセンサを例示する断面図（その２）である。FIG. 2 is a cross-sectional view (part 2) illustrating the strain sensor according to the first embodiment; 第１実施形態に係る歪みセンサの使用例を示す図である。It is a figure which shows the usage example of the strain sensor which concerns on 1st Embodiment. 第１実施形態に係る歪みセンサの接続例を示す図である。It is a figure which shows the connection example of the strain sensor which concerns on 1st Embodiment. 比較例に係る歪みセンサを例示する断面図である。FIG. 5 is a cross-sectional view illustrating a strain sensor according to a comparative example; 比較例に係る歪みセンサの接続例を示す図である。FIG. 5 is a diagram showing a connection example of a strain sensor according to a comparative example; 比較例に係る歪みセンサの出力電圧の測定例を示す図である。FIG. 5 is a diagram showing an example of measurement of output voltage of a strain sensor according to a comparative example; 第１実施形態に係る歪みセンサの出力電圧の測定例を示す図である。It is a figure which shows the example of a measurement of the output voltage of the distortion sensor which concerns on 1st Embodiment. 第１実施形態の変形例１に係る歪みセンサを例示する断面図である。FIG. 7 is a cross-sectional view illustrating a strain sensor according to Modification 1 of the first embodiment;
　以下、図面を参照して発明を実施するための形態について説明する。各図面において、同一構成部分には同一符号を付し、重複した説明を省略する場合がある。 Hereinafter, the embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and redundant description may be omitted.
　〈第１実施形態〉
　［歪みセンサの構造］
　図１は、第１実施形態に係る歪みセンサを例示する平面図である。図２は、第１実施形態に係る歪みセンサを例示する断面図であり、図１のＡ－Ａ線に沿う断面を示している。図３は、第１実施形態に係る歪みセンサを例示する断面図であり、図１のＢ－Ｂ線に沿う断面を示している。図１～図３を参照すると、歪みセンサ１は、フィルム基板１０と、歪み検出素子２０と、シールド膜３０と、端子４０Ａ、４０Ｂ、及び４０Ｃと、カバー膜５０とを有している。なお、図１では、便宜上、カバー膜５０の外縁のみを破線で示している。 <First Embodiment>
[Structure of strain sensor]
1 is a plan view illustrating a strain sensor according to a first embodiment; FIG. FIG. 2 is a cross-sectional view illustrating the strain sensor according to the first embodiment, showing a cross section along line AA in FIG. FIG. 3 is a cross-sectional view illustrating the strain sensor according to the first embodiment, showing a cross section along line BB in FIG. 1 to 3, the strain sensor 1 has a film substrate 10, a strain detecting element 20, a shield film 30, terminals 40A, 40B and 40C, and a cover film 50. FIG. In FIG. 1, only the outer edge of the cover film 50 is indicated by broken lines for the sake of convenience.
　本実施形態では、便宜上、歪みセンサ１において、フィルム基板１０の歪み検出素子２０が設けられている側を上側又は一方の側、歪み検出素子２０が設けられていない側を下側又は他方の側とする。又、各部位の歪み検出素子２０が設けられている側の面を一方の面又は上面、歪み検出素子２０が設けられていない側の面を他方の面又は下面とする。但し、歪みセンサ１は天地逆の状態で用いることができ、又は任意の角度で配置できる。又、平面視とは対象物をフィルム基板１０の上面１０ａの法線方向から視ることを指し、平面形状とは対象物をフィルム基板１０の上面１０ａの法線方向から視た形状を指すものとする。 In this embodiment, for convenience, in the strain sensor 1, the side of the film substrate 10 provided with the strain detection element 20 is the upper side or one side, and the side without the strain detection element 20 is the lower side or the other side. and Also, the surface on which the strain detection element 20 of each part is provided is defined as one surface or upper surface, and the surface on which the distortion detection element 20 is not provided is defined as the other surface or lower surface. However, the strain sensor 1 can be used upside down or arranged at any angle. Further, the term "planar view" refers to viewing an object from the direction normal to the upper surface 10a of the film substrate 10, and the term "planar shape" refers to the shape of the object viewed from the direction normal to the upper surface 10a of the film substrate 10. and
　フィルム基板１０は、歪み検出素子２０等を形成するためのベース層となる部材であり、可撓性を有する。フィルム基板１０の膜厚は、特に制限はなく、目的に応じて適宜選択できるが、例えば、２５μｍ～５０μｍ程度とすることができる。平面視でのフィルム基板１０の縦の長さ及び横の長さは、特に制限はなく、目的に応じて適宜選択できるが、例えば、それぞれ１ｍｍ～５ｍｍ程度とすることができる。 The film substrate 10 is a member that serves as a base layer for forming the strain detection element 20 and the like, and has flexibility. The film thickness of the film substrate 10 is not particularly limited and can be appropriately selected according to the purpose. The vertical length and horizontal length of the film substrate 10 in a plan view are not particularly limited and can be appropriately selected according to the purpose, but each can be, for example, about 1 mm to 5 mm.
　フィルム基板１０は、例えば、ＰＩ（ポリイミド）樹脂等の絶縁樹脂から形成されている。フィルム基板１０は、エポキシ樹脂、ＰＥＥＫ（ポリエーテルエーテルケトン）樹脂、ＰＥＮ（ポリエチレンナフタレート）樹脂、ＰＥＴ（ポリエチレンテレフタレート）樹脂、ＰＰＳ（ポリフェニレンサルファイド）樹脂、ポリオレフィン樹脂等の絶縁樹脂から形成されてもよい。 The film substrate 10 is made of insulating resin such as PI (polyimide) resin, for example. The film substrate 10 may be made of an insulating resin such as epoxy resin, PEEK (polyetheretherketone) resin, PEN (polyethylene naphthalate) resin, PET (polyethylene terephthalate) resin, PPS (polyphenylene sulfide) resin, or polyolefin resin. good.
　歪み検出素子２０は、フィルム基板１０の上面１０ａに所定のパターンで形成された薄膜であり、歪みを受けて抵抗値変化を生じる受感部である。歪み検出素子２０は、フィルム基板１０の上面１０ａに直接形成されてもよいし、フィルム基板１０の上面１０ａに他の層を介して形成されてもよい。なお、図１では、便宜上、歪み検出素子２０を梨地模様で示している。 The strain detection element 20 is a thin film formed in a predetermined pattern on the upper surface 10a of the film substrate 10, and is a sensing part that undergoes a change in resistance when subjected to strain. The strain detection element 20 may be formed directly on the top surface 10a of the film substrate 10, or may be formed on the top surface 10a of the film substrate 10 via another layer. In addition, in FIG. 1, the distortion detection element 20 is shown with a pear-skin pattern for the sake of convenience.
　歪み検出素子２０は、例えば、複数の細長状部が長手方向を同一方向（図１のＡ－Ａ線の方向）に向けて所定間隔で配置され、隣接する細長状部の端部が互い違いに連結されて、全体としてジグザグに折り返す構造である。複数の細長状部の長手方向がグリッド方向となり、グリッド方向と垂直な方向がグリッド幅方向となる。 In the strain detection element 20, for example, a plurality of elongated portions are arranged at predetermined intervals with their longitudinal directions directed in the same direction (the direction of line AA in FIG. 1), and the ends of adjacent elongated portions are staggered. It is a structure that is connected and folded in a zigzag as a whole. The longitudinal direction of the elongated portions is the grid direction, and the direction perpendicular to the grid direction is the grid width direction.
　歪み検出素子２０は、例えば、Ｃｒ及びＣｒＮを含む導電性の金属膜である。歪み検出素子２０の膜厚は、例えば、１００ｎｍ～５００ｎｍ程度とすることができる。歪み検出素子２０の幅は、例えば、５０μｍ～３００μｍ程度とすることができる。 The strain detection element 20 is, for example, a conductive metal film containing Cr and CrN. The film thickness of the strain detection element 20 can be, for example, about 100 nm to 500 nm. The width of the strain detection element 20 can be, for example, about 50 μm to 300 μm.
　シールド膜３０は、フィルム基板１０の上面１０ａに所定のパターンで形成された導電性の金属膜である。シールド膜３０は、フィルム基板１０の上面１０ａに直接形成されてもよいし、フィルム基板１０の上面１０ａに他の層を介して形成されてもよい。シールド膜３０は、平面視、歪み検出素子２０と離間して歪み検出素子２０の周辺を囲うように配置されている。シールド膜３０は、歪み検出素子２０とは電気的に接続されていない。なお、図１では、便宜上、シールド膜３０を、歪み検出素子２０とは異なる梨地模様で示している。 The shield film 30 is a conductive metal film formed on the upper surface 10a of the film substrate 10 in a predetermined pattern. The shield film 30 may be formed directly on the upper surface 10a of the film substrate 10, or may be formed on the upper surface 10a of the film substrate 10 via another layer. The shield film 30 is arranged so as to surround the distortion detection element 20 while being separated from the distortion detection element 20 in plan view. The shield film 30 is not electrically connected to the strain sensing element 20 . In FIG. 1, the shield film 30 is shown with a pear-skin pattern different from that of the strain detection element 20 for the sake of convenience.
　シールド膜３０は、例えば、歪み検出素子２０と同一の材料で形成されている。つまり、歪み検出素子２０がＣｒ及びＣｒＮを含む導電性の金属膜であれば、シールド膜３０もＣｒ及びＣｒＮを含む導電性の金属膜であり、厚さも歪み検出素子２０と同一となる。この場合、シールド膜３０を歪み検出素子２０と同一工程で形成することにより、製造工程を簡略化できる。 The shield film 30 is made of the same material as the strain detection element 20, for example. That is, if the strain sensing element 20 is a conductive metal film containing Cr and CrN, the shield film 30 is also a conductive metal film containing Cr and CrN and has the same thickness as the strain sensing element 20 . In this case, the manufacturing process can be simplified by forming the shield film 30 in the same process as the strain detection element 20 .
　シールド膜３０は、端子４０Ｃを介してＧＮＤに接続されることでシールド効果を生じて外乱ノイズを吸収し、歪み検出素子２０に重畳される外乱ノイズを低減できる。シールド膜３０は、歪み検出素子２０よりもインピーダンスの低い材料で形成されてもよい。例えば、歪み検出素子２０がＣｒ及びＣｒＮを含む導電性の金属膜であれば、シールド膜３０をＮｉ、Ａｌ、Ｃｕ等を含む導電性の金属膜とすることができる。シールド膜３０を歪み検出素子２０よりもインピーダンスの低い材料で形成することにより、歪み検出素子２０に重畳される外乱ノイズを低減する効果を向上できる。 The shield film 30 is connected to GND via the terminal 40C to generate a shield effect, absorb disturbance noise, and reduce the disturbance noise superimposed on the strain detection element 20. The shield film 30 may be made of a material with lower impedance than the strain detection element 20 . For example, if the strain sensing element 20 is a conductive metal film containing Cr and CrN, the shield film 30 can be a conductive metal film containing Ni, Al, Cu, or the like. By forming the shield film 30 with a material having a lower impedance than the strain detection element 20, the effect of reducing disturbance noise superimposed on the strain detection element 20 can be improved.
　シールド膜３０と歪み検出素子２０との間隔ｄは、加工精度の観点から５μｍ以上であることが好ましい。また、間隔ｄが５μｍ未満であると、シールド膜３０と歪み検出素子２０との間の線間容量が大きくなり、容量結合短絡によりシールド膜３０が吸収したノイズを歪み検出素子２０に伝搬し易くなるため好ましくない。また、シールド膜３０と歪み検出素子２０との間隔ｄは、シールド膜３０が外乱ノイズを吸収して十分なシールド効果を得る観点から、２０μｍ以下であることが好ましい。シールド膜３０と歪み検出素子２０との間隔ｄが１０μｍ以下であると、さらに大きなシールド効果を得られる点でより好ましい。 The distance d between the shield film 30 and the strain detection element 20 is preferably 5 μm or more from the viewpoint of processing accuracy. Further, when the distance d is less than 5 μm, the line capacitance between the shield film 30 and the strain detection element 20 becomes large, and the noise absorbed by the shield film 30 due to capacitive coupling short-circuit easily propagates to the strain detection element 20. It is not preferable because Moreover, the distance d between the shield film 30 and the strain detection element 20 is preferably 20 μm or less from the viewpoint of obtaining a sufficient shield effect by the shield film 30 absorbing disturbance noise. It is more preferable that the distance d between the shield film 30 and the strain detection element 20 is 10 μm or less in that a greater shield effect can be obtained.
　端子４０Ａ及び４０Ｂは、歪み検出素子２０の両端部から延在しており、平面視において、歪み検出素子２０よりも拡幅して略矩形状に形成されている。端子４０Ａ及び４０Ｂは、歪みにより生じる歪み検出素子２０の抵抗値の変化を外部に出力するための一対の電極であり、例えば、外部接続用のリード線等（例えば、撚線）が接合される。 The terminals 40A and 40B extend from both ends of the strain detection element 20 and are formed in a substantially rectangular shape wider than the strain detection element 20 in plan view. The terminals 40A and 40B are a pair of electrodes for outputting to the outside the change in the resistance value of the strain detecting element 20 caused by strain, and for example, lead wires for external connection (for example, twisted wires) are joined. .
　端子４０Ａ及び４０Ｂは、例えば、複数の金属膜が積層された積層構造である。具体的には、図１及び図２の例では、端子４０Ａは、歪み検出素子２０の両端部から延在する金属膜４１と、金属膜４１の上面に形成された金属膜４５とを有している。なお、金属膜４１は、歪み検出素子２０とは便宜上別符号としているが、歪み検出素子２０と同一工程において同一材料により一体に形成される。 The terminals 40A and 40B have, for example, a laminated structure in which a plurality of metal films are laminated. Specifically, in the example of FIGS. 1 and 2, the terminal 40A has a metal film 41 extending from both ends of the strain sensing element 20 and a metal film 45 formed on the upper surface of the metal film 41. ing. Although the metal film 41 and the strain detecting element 20 are given different reference numerals for the sake of convenience, the metal film 41 and the strain detecting element 20 are integrally formed from the same material in the same process.
　金属膜４５は、例えば、金属膜４１よりもはんだ付け性が良好な金属から形成できる。金属膜４２の材料は、例えば、Ｃｕ、Ｃｕ合金、Ｎｉ、又はＮｉ合金である。金属膜４２の厚さは、例えば、４μｍ以上３０μｍ以下である。 The metal film 45 can be formed, for example, from a metal having better solderability than the metal film 41. The material of the metal film 42 is, for example, Cu, Cu alloy, Ni, or Ni alloy. The thickness of the metal film 42 is, for example, 4 μm or more and 30 μm or less.
　金属膜４５の上面に、金属膜４５よりもさらにはんだ濡れ性の良好な材料を積層してもよい。例えば、金属膜４２の材料がＣｕ、Ｃｕ合金、Ｎｉ、又はＮｉ合金であれば、積層する金属膜の材料としてＡｕ（金）を用いることができる。Ｃｕ、Ｃｕ合金、Ｎｉ、又はＮｉ合金の表面をＡｕで被覆することにより、Ｃｕ、Ｃｕ合金、Ｎｉ、又はＮｉ合金の酸化及び腐食を防止できると共に、良好なはんだ濡れ性を得ることができる。 A material having better solder wettability than the metal film 45 may be laminated on the upper surface of the metal film 45 . For example, if the material of the metal film 42 is Cu, Cu alloy, Ni, or Ni alloy, Au (gold) can be used as the material of the stacked metal film. By coating the surface of Cu, Cu alloy, Ni, or Ni alloy with Au, oxidation and corrosion of Cu, Cu alloy, Ni, or Ni alloy can be prevented, and good solder wettability can be obtained.
　端子４０Ｃは、シールド膜３０と電気的に接続されている。端子４０Ｃは、シールド膜３０を歪みセンサ１の外部にあるＧＮＤに接続するための電極であり、例えば、外部接続用のリード線（例えば、撚線）等が接合される。図１では、端子４０Ｃは、平面視で、端子４０Ａと端子４０Ｂに挟まれた位置に配置されているが、端子４０Ｃは任意の位置に配置してかまわない。また、シールド膜３０と電気的に接続された端子は、複数個配置されてもかまわない。 The terminal 40C is electrically connected to the shield film 30. The terminal 40C is an electrode for connecting the shield film 30 to GND outside the strain sensor 1, and is connected to, for example, a lead wire (for example, twisted wire) for external connection. In FIG. 1, the terminal 40C is arranged at a position sandwiched between the terminals 40A and 40B in plan view, but the terminal 40C may be arranged at an arbitrary position. Also, a plurality of terminals electrically connected to the shield film 30 may be arranged.
　端子４０Ｃは、例えば、複数の金属膜が積層された積層構造である。具体的には、図１及び図３の例では、端子４０Ｃは、シールド膜３０から延在する金属膜４２と、金属膜４２の上面に形成された金属膜４５とを有している。なお、金属膜４２は、シールド膜３０とは便宜上別符号としているが、シールド膜３０と同一工程において同一材料により一体に形成される。言い換えれば、金属膜４５の下方に位置するシールド膜３０を、便宜上金属膜４２と称している。金属膜４５については、端子４０Ａ及び４０Ｂで説明した通りである。 The terminal 40C has, for example, a laminated structure in which a plurality of metal films are laminated. Specifically, in the examples of FIGS. 1 and 3, the terminal 40C has a metal film 42 extending from the shield film 30 and a metal film 45 formed on the upper surface of the metal film 42. As shown in FIG. Although the metal film 42 and the shield film 30 are denoted by different symbols for the sake of convenience, they are integrally formed of the same material in the same process as the shield film 30 . In other words, the shield film 30 positioned below the metal film 45 is called the metal film 42 for convenience. The metal film 45 is as described for the terminals 40A and 40B.
　カバー膜５０は、歪み検出素子２０及びシールド膜３０を被覆し、端子４０Ａ、４０Ｂ、及び４０Ｃの各々の上面の少なくとも一部を露出するように設けられている保護膜である。カバー膜５０の開口部５０Ａから端子４０Ａの上面の少なくとも一部が露出し、カバー膜５０の開口部５０Ｂから端子４０Ｂの上面の少なくとも一部が露出し、カバー膜５０の開口部５０Ｃから端子４０Ｃの上面の少なくとも一部が露出している。 The cover film 50 is a protective film that covers the strain detection element 20 and the shield film 30 and exposes at least a portion of the upper surface of each of the terminals 40A, 40B, and 40C. At least a portion of the upper surface of the terminal 40A is exposed from the opening 50A of the cover film 50, at least a portion of the upper surface of the terminal 40B is exposed from the opening 50B of the cover film 50, and the terminal 40C is exposed from the opening 50C of the cover film 50. at least a portion of the top surface of the is exposed.
　カバー膜５０は、例えば、ＰＩ樹脂、エポキシ樹脂、ＰＥＥＫ樹脂、ＰＥＮ樹脂、ＰＥＴ樹脂、ＰＰＳ樹脂、複合樹脂（例えば、シリコーン樹脂、ポリオレフィン樹脂）等の絶縁樹脂（有機膜）から形成できる。カバー膜５０は、シリコン酸化膜（ＳｉＯ２）、ガラス膜、シリコン窒化膜（ＳｉＮ）等の無機膜から形成してもよい。 The cover film 50 can be formed from an insulating resin (organic film) such as PI resin, epoxy resin, PEEK resin, PEN resin, PET resin, PPS resin, composite resin (for example, silicone resin, polyolefin resin). The cover film 50 may be formed from an inorganic film such as a silicon oxide film ( SiO2 ), a glass film, a silicon nitride film (SiN), or the like.
　カバー膜５０を設けることで、歪み検出素子２０及びシールド膜３０に機械的な損傷等が生じることを防止できる。又、カバー膜５０を設けることで、歪み検出素子２０及びシールド膜３０を湿気等から保護できる。 By providing the cover film 50, it is possible to prevent the strain detection element 20 and the shield film 30 from being mechanically damaged. Also, by providing the cover film 50, the strain detecting element 20 and the shield film 30 can be protected from moisture and the like.
　［歪みセンサの製造方法］
　ここでは、歪み検出素子２０及びシールド膜３０を同一の材料で形成する例を示す。歪みセンサ１を製造するためには、まず、フィルム基板１０を準備し、フィルム基板１０の上面１０ａの全体に金属膜（便宜上、金属膜Ａとする）を形成する。金属膜Ａは、最終的にパターニングされて歪み検出素子２０及びシールド膜３０（金属膜４１及び４２も含む）となる膜である。従って、金属膜Ａの材料や厚さは、前述の歪み検出素子２０及びシールド膜３０の材料や厚さと同様である。金属膜Ａは、例えば、スパッタリング法により成膜できる。 [Manufacturing method of strain sensor]
Here, an example is shown in which the strain detection element 20 and the shield film 30 are made of the same material. In order to manufacture the strain sensor 1 , first, the film substrate 10 is prepared, and a metal film (referred to as metal film A for convenience) is formed on the entire upper surface 10 a of the film substrate 10 . The metal film A is a film that is finally patterned to become the strain sensing element 20 and the shield film 30 (including the metal films 41 and 42). Therefore, the material and thickness of the metal film A are the same as those of the strain detecting element 20 and the shield film 30 described above. The metal film A can be formed by sputtering, for example.
　次に、フォトリソグラフィによって金属膜Ａをパターニングし、図１に示す平面形状の歪み検出素子２０及びシールド膜３０（金属膜４１及び４２も含む）を形成する。具体的には、金属膜Ａ上にレジストを塗布し、フォトリソグラフィ及びエッチングにより、歪み検出素子２０及びシールド膜３０（金属膜４１及び４２も含む）をパターニングする。パターニングが終了後、レジストを剥離する。 Next, the metal film A is patterned by photolithography to form the planar strain detection element 20 and the shield film 30 (including the metal films 41 and 42) shown in FIG. Specifically, a resist is applied on the metal film A, and the strain detecting element 20 and the shield film 30 (including the metal films 41 and 42) are patterned by photolithography and etching. After the patterning is finished, the resist is removed.
　次に、パターニングされた歪み検出素子２０及びシールド膜３０（金属膜４１及び４２も含む）を被覆するように、フィルム基板１０の上面１０ａの全体にレジストを塗布する。そして、フォトリソグラフィ及びエッチングにより、レジストをパターニングし、端子４０Ａ、４０Ｂ、及び４０Ｃとなる部分を露出するように開口部を形成する。そして、電解めっき法や無電解めっき法等により、各開口部内に金属膜４５を成膜して端子４０Ａ、４０Ｂ、及び４０Ｃを形成する。端子４０Ａ、４０Ｂ、及び４０Ｃを形成後、レジストを剥離する。 Next, a resist is applied to the entire upper surface 10a of the film substrate 10 so as to cover the patterned strain sensing element 20 and the shield film 30 (including the metal films 41 and 42). Then, the resist is patterned by photolithography and etching, and openings are formed so as to expose the portions that will become the terminals 40A, 40B, and 40C. Then, the terminals 40A, 40B, and 40C are formed by depositing a metal film 45 in each opening by an electrolytic plating method, an electroless plating method, or the like. After forming the terminals 40A, 40B, and 40C, the resist is removed.
　次に、パターニングされた歪み検出素子２０及びシールド膜３０（端子４０Ａ、４０Ｂ、及び４０Ｃも含む）を被覆するように、フィルム基板１０の上面１０ａの全体にカバー膜５０を形成し、フォトリソグラフィ及びエッチングにより、開口部５０Ａ、５０Ｂ、及び５０Ｃを形成する。開口部５０Ａから端子４０Ａの上面の少なくとも一部が露出し、カバー膜５０の開口部５０Ｂから端子４０Ｂの上面の少なくとも一部が露出し、カバー膜５０の開口部５０Ｃから端子４０Ｃの上面の少なくとも一部が露出する。以上の工程により、歪みセンサ１が完成する。 Next, a cover film 50 is formed over the entire upper surface 10a of the film substrate 10 so as to cover the patterned strain sensing element 20 and the shield film 30 (including the terminals 40A, 40B, and 40C). Etching forms openings 50A, 50B, and 50C. At least part of the upper surface of the terminal 40A is exposed through the opening 50A, at least part of the upper surface of the terminal 40B is exposed through the opening 50B of the cover film 50, and at least the upper surface of the terminal 40C is exposed through the opening 50C of the cover film 50. partly exposed. Through the above steps, the strain sensor 1 is completed.
　［歪みセンサの使用例］
　図４は、第１実施形態に係る歪みセンサの使用例を示す図である。図４の例では、歪みセンサ１は、接着層１１０を介して起歪体１２０と接着されている。具体的には、歪みセンサ１のフィルム基板１０の下面が、接着層１１０を介して起歪体１２０の上面と接着されている。 [Usage example of strain sensor]
FIG. 4 is a diagram showing a usage example of the strain sensor according to the first embodiment. In the example of FIG. 4 , the strain sensor 1 is adhered to the strain body 120 via the adhesive layer 110 . Specifically, the lower surface of the film substrate 10 of the strain sensor 1 is adhered to the upper surface of the strain body 120 via the adhesive layer 110 .
　接着層１１０は、歪みセンサ１と起歪体１２０とを接着する機能を有する材料であれば、特に制限はなく、目的に応じて適宜選択できるが、例えば、エポキシ樹脂、変性エポキシ樹脂、シリコーン樹脂、変性シリコーン樹脂、ウレタン樹脂、変性ウレタン樹脂等を用いることができる。 The adhesive layer 110 is not particularly limited as long as it has a function of adhering the strain sensor 1 and the strain generating body 120, and can be appropriately selected depending on the purpose. Examples include epoxy resin, modified epoxy resin, and silicone resin. , modified silicone resin, urethane resin, modified urethane resin, and the like can be used.
　起歪体１２０は、例えば、Ｆｅ、ＳＵＳ（ステンレス鋼）、Ａｌ等の金属やＰＥＥＫ等の樹脂から形成され、印加される力に応じて変形する（歪みを生じる）物体である。歪みセンサ１は、起歪体１２０に生じる歪みを歪み検出素子２０の抵抗値変化として検出することができる。 The strain-generating body 120 is an object that is made of, for example, a metal such as Fe, SUS (stainless steel), or Al, or a resin such as PEEK, and that deforms (generates strain) according to applied force. The strain sensor 1 can detect strain occurring in the strain generating element 120 as a change in the resistance value of the strain detecting element 20 .
　カバー膜５０から露出する端子４０Ａ、４０Ｂ、及び４０Ｃの各々の上面は、接合材１３０を介して接続部材１４０と電気的に接続されている。接合材１３０は、例えば、はんだや導電性ペーストである。接続部材１４０は、例えば、リード線やフレキシブルプリント配線板等である。なお、歪みセンサ１に接合材１３０及び接続部材１４０を取り付けた状態で、市場に流通させてもよい。 The upper surface of each of the terminals 40A, 40B, and 40C exposed from the cover film 50 is electrically connected to the connection member 140 via the bonding material 130. The bonding material 130 is, for example, solder or conductive paste. The connection member 140 is, for example, a lead wire, a flexible printed wiring board, or the like. Note that the strain sensor 1 with the bonding material 130 and the connection member 140 attached thereto may be distributed on the market.
　図５は、第１実施形態に係る歪みセンサの接続例を示す図である。図５の例では、歪みセンサ１は、接続部材１４０を介して、歪みセンサ１の外部に配置された測定部２００に接続されている。 FIG. 5 is a diagram showing a connection example of strain sensors according to the first embodiment. In the example of FIG. 5 , the strain sensor 1 is connected to the measuring section 200 arranged outside the strain sensor 1 via the connection member 140 .
　測定部２００は、ブリッジ回路を有している。ブリッジ回路は、３辺が固定抵抗Ｒ１、Ｒ２、及びＲ３で構成され、他の１辺が接続部材１４０並びに端子４０Ａ及び４０Ｂを介して歪み検出素子２０に接続されている。又、ブリッジ回路の一対の対角点間には、直流電圧ＶＤＤが印加されている。ブリッジ回路のＧＮＤは、接続部材１４０及び端子４０Ｃを介してシールド膜３０に接続されている。 The measuring section 200 has a bridge circuit. The bridge circuit has three sides composed of fixed resistors R1, R2, and R3, and the other side connected to the strain detecting element 20 via the connection member 140 and the terminals 40A and 40B. A DC voltage VDD is applied between a pair of diagonal points of the bridge circuit. GND of the bridge circuit is connected to the shield film 30 via the connecting member 140 and the terminal 40C.
　この構成により、ブリッジ回路の他の一対の対角点間は、歪み検出素子２０のひずみに応じたアナログの電圧Ｖ１及びＶ２が出力される。シールド膜３０は、ブリッジ回路のＧＮＤに接続されることでシールド効果を生じて外乱ノイズを吸収し、歪み検出素子２０に重畳される外乱ノイズを低減できる。そのため、ノイズの少ない電圧Ｖ１及びＶ２が得られる。 With this configuration, analog voltages V1 and V2 corresponding to the strain of the strain detecting element 20 are output between the other pair of diagonal points of the bridge circuit. The shield film 30 is connected to the GND of the bridge circuit to produce a shield effect, absorb disturbance noise, and reduce disturbance noise superimposed on the strain detection element 20 . Therefore, voltages V1 and V2 with little noise are obtained.
　図６は、比較例に係る歪みセンサを例示する断面図であり、図１のＡ－Ａ線に相当する断面を示している。図６に示す歪みセンサ１Ｘは、シールド膜３０及び端子４０Ｃを有していない点が、歪みセンサ１と相違する。 FIG. 6 is a cross-sectional view illustrating a strain sensor according to a comparative example, showing a cross section corresponding to line AA in FIG. A strain sensor 1X shown in FIG. 6 differs from the strain sensor 1 in that it does not have a shield film 30 and terminals 40C.
　図６において、歪みセンサ１Ｘは、図４と同様に、接着層１１０を介して起歪体１２０と接着されている。また、図６に示す歪みセンサ１Ｘは、図４と同様に、カバー膜５０から露出する端子４０Ａ及び４０Ｂの各々の上面が、接合材１３０を介して接続部材１４０と電気的に接続されている。また、図７に示すように、歪みセンサ１Ｘは、接続部材１４０を介して、歪みセンサ１Ｘの外部に配置された測定部２００に接続されている。 In FIG. 6, the strain sensor 1X is adhered to the strain body 120 via the adhesive layer 110, as in FIG. Moreover, in the strain sensor 1X shown in FIG. 6, similarly to FIG. . Further, as shown in FIG. 7, the strain sensor 1X is connected via a connecting member 140 to a measuring section 200 arranged outside the strain sensor 1X.
　図８は、比較例に係る歪みセンサの出力電圧の測定例を示す図である。ここで、歪みセンサ１Ｘの出力電圧とは、図７のＶ１とＶ２との間の電圧を増幅したものである。一方、図９は、第１実施形態に係る歪みセンサの出力電圧の測定例を示す図である。ここで、歪みセンサ１の出力電圧とは、図５のＶ１とＶ２との間の電圧を増幅したものである。図８と図９とは、同一の条件（同一の環境）で測定されている。図８のＸ軸（測定時間）、Ｙ軸（出力電圧）のスケールは、図９のＸ軸（測定時間）、Ｙ軸（出力電圧）のスケールと合わせている。図８と図９とを比較するとわかるように、歪みセンサ１では、比較例に係る歪みセンサ１Ｘよりも出力電圧に重畳される外乱ノイズが大幅に低減されている。 FIG. 8 is a diagram showing a measurement example of the output voltage of the strain sensor according to the comparative example. Here, the output voltage of the strain sensor 1X is obtained by amplifying the voltage between V1 and V2 in FIG. On the other hand, FIG. 9 is a diagram showing a measurement example of the output voltage of the strain sensor according to the first embodiment. Here, the output voltage of the strain sensor 1 is obtained by amplifying the voltage between V1 and V2 in FIG. 8 and 9 are measured under the same conditions (same environment). The X-axis (measurement time) and Y-axis (output voltage) scales in FIG. 8 match the X-axis (measurement time) and Y-axis (output voltage) scales in FIG. As can be seen by comparing FIGS. 8 and 9, in the strain sensor 1, the disturbance noise superimposed on the output voltage is significantly reduced as compared with the strain sensor 1X according to the comparative example.
　このように、平面視で歪み検出素子２０と離間して歪み検出素子２０の周辺を囲うシールド膜３０を設け、シールド膜３０をブリッジ回路のＧＮＤに接続することで、シールド膜３０が外乱ノイズを吸収し、歪み検出素子２０に重畳される外乱ノイズを低減できる。その結果、Ｓ／Ｎ比が改善されてノイズの少ない出力電圧が得られるため、歪みセンサ１の検出感度が向上する。 In this manner, the shield film 30 is provided so as to surround the distortion detection element 20 while being separated from the distortion detection element 20 in a plan view, and is connected to the GND of the bridge circuit so that the shield film 30 can block disturbance noise. Disturbance noise that is absorbed and superimposed on the strain detection element 20 can be reduced. As a result, the S/N ratio is improved and an output voltage with little noise is obtained, so the detection sensitivity of the strain sensor 1 is improved.
　また、歪み検出素子２０が外乱ノイズの影響を受けにくいため、歪みセンサ１の検出感度が安定する。また、歪み検出素子２０が外乱ノイズの影響を受けにくいため、端子４０Ａ及び４０Ｂとブリッジ回路との距離を増長することができ、歪みセンサ１及び／又はブリッジ回路の配置の自由度が向上する。 In addition, since the strain detection element 20 is less susceptible to disturbance noise, the detection sensitivity of the strain sensor 1 is stabilized. In addition, since the strain detection element 20 is less susceptible to disturbance noise, the distance between the terminals 40A and 40B and the bridge circuit can be increased, thereby improving the degree of freedom in arranging the strain sensor 1 and/or the bridge circuit.
　また、歪みセンサ１では、シールド膜３０を歪み検出素子２０と同様にフィルム基板１０の上面１０ａに形成するため、歪みセンサ１の厚さの増加を抑えることができる。すなわち、歪みセンサ１は、厚さの増加を抑えつつ外乱ノイズの影響を低減可能である。 Also, in the strain sensor 1, the shield film 30 is formed on the upper surface 10a of the film substrate 10 in the same manner as the strain detecting element 20, so an increase in the thickness of the strain sensor 1 can be suppressed. That is, the strain sensor 1 can reduce the influence of disturbance noise while suppressing an increase in thickness.
　〈第１実施形態の変形例１〉
　第１実施形態の変形例１では、シールド膜が積層構造である例を示す。なお、第１実施形態の変形例１において、既に説明した実施形態と同一構成部についての説明は省略する場合がある。 <Modification 1 of the first embodiment>
Modification 1 of the first embodiment shows an example in which the shield film has a laminated structure. In addition, in Modification 1 of the first embodiment, the description of the same components as those of the already described embodiment may be omitted.
　図１０は、第１実施形態の変形例１に係る歪みセンサを例示する断面図であり、図１のＡ－Ａ線に相当する断面を示している。図１０に示すように、歪みセンサ１Ａは、シールド膜３０がシールド膜３０Ａに置換された点が、歪みセンサ１（図２等参照）と相違する。 FIG. 10 is a cross-sectional view illustrating a strain sensor according to Modification 1 of the first embodiment, showing a cross section corresponding to line AA in FIG. As shown in FIG. 10, the strain sensor 1A differs from the strain sensor 1 (see FIG. 2, etc.) in that the shield film 30 is replaced with a shield film 30A.
　シールド膜３０Ａは、金属膜３１と、金属膜３１の上面に形成された金属膜３５とを有している。金属膜３１は、便宜上別符号としているが、歪みセンサ１のシールド膜３０と同一の層である。金属膜３５は、金属膜３１よりもインピーダンスの低い材料で形成されている。金属膜３５は、例えば、金属膜４５と同一工程において同一材料により一体に形成できる。例えば、金属膜３１はＣｒを含む金属膜であり、金属膜３５はＣｕを含む金属膜である。 The shield film 30A has a metal film 31 and a metal film 35 formed on the upper surface of the metal film 31 . The metal film 31 is the same layer as the shield film 30 of the strain sensor 1, although it is denoted by a different symbol for the sake of convenience. The metal film 35 is made of a material whose impedance is lower than that of the metal film 31 . The metal film 35 can be integrally formed with the same material in the same step as the metal film 45, for example. For example, the metal film 31 is a metal film containing Cr, and the metal film 35 is a metal film containing Cu.
　シールド膜３０Ａは、例えば、次のようにして形成する。第１実施形態における端子４０Ａ、４０Ｂ、及び４０Ｃとなる部分を露出するように開口部を形成する工程で、金属膜３１を露出する第２開口部も同時に形成する。そして、電解めっき法や無電解めっき法等により、各開口部内に金属膜４５を成膜して端子４０Ａ、４０Ｂ、及び４０Ｃを形成する際に、同時に第２開口部内に露出する金属膜３１上に金属膜３５を成膜してシールド膜３０Ａを形成する。 The shield film 30A is formed, for example, as follows. In the step of forming the openings to expose the portions to be the terminals 40A, 40B, and 40C in the first embodiment, the second openings to expose the metal film 31 are also formed at the same time. When the terminals 40A, 40B, and 40C are formed by depositing the metal film 45 in each opening by an electrolytic plating method, an electroless plating method, or the like, the metal film 31 exposed in the second opening is simultaneously formed. A shield film 30A is formed by depositing a metal film 35 on the substrate.
　このように、シールド膜３０Ａを２層構造とし、金属膜３５を金属膜３１よりもインピーダンスの低い材料で形成することで、シールド膜３０Ａの外乱ノイズの吸収性を向上させることができる。例えば、歪み検出素子２０がＣｒ及びＣｒＮを含む導電性の金属膜である場合、比較的インピーダンスが高い。そこで、金属膜３１上に、金属膜３１よりもインピーダンスの低いＣｕ等により形成された金属膜３５を積層することで、シールド膜３０Ａのインピーダンスが低下し、シールド膜３０Ａの外乱ノイズの吸収性が向上する。 Thus, by forming the shield film 30A in a two-layer structure and forming the metal film 35 with a material having a lower impedance than the metal film 31, the ability of the shield film 30A to absorb disturbance noise can be improved. For example, when the strain sensing element 20 is a conductive metal film containing Cr and CrN, the impedance is relatively high. Therefore, by laminating a metal film 35 formed of Cu or the like having an impedance lower than that of the metal film 31 on the metal film 31, the impedance of the shield film 30A is lowered and the disturbance noise absorbability of the shield film 30A is improved. improves.
　また、金属膜３５を金属膜４５と同一工程において同一材料により一体に形成することで、新たな工程を追加することなく、外乱ノイズの吸収性に優れたシールド膜３０Ａを形成できる。 Also, by integrally forming the metal film 35 with the same material in the same process as the metal film 45, the shield film 30A with excellent disturbance noise absorption can be formed without adding a new process.
　以上、好ましい実施形態等について詳説したが、上述した実施形態等に制限されることはなく、特許請求の範囲に記載された範囲を逸脱することなく、上述した実施形態等に種々の変形及び置換を加えることができる。 Although the preferred embodiments and the like have been described in detail above, the present invention is not limited to the above-described embodiments and the like, and various modifications and substitutions can be made to the above-described embodiments and the like without departing from the scope of the claims. can be added.
　本国際出願は２０２１年１月２８日に出願した日本国特許出願２０２１－０１１８１１号に基づく優先権を主張するものであり、日本国特許出願２０２１－０１１８１１号の全内容を本国際出願に援用する。 This international application claims priority based on Japanese Patent Application No. 2021-011811 filed on January 28, 2021, and the entire contents of Japanese Patent Application No. 2021-011811 are incorporated into this international application. .
１，１Ａ　歪みセンサ、１０　フィルム基板、１０ａ　上面、２０　歪み検出素子、３０，３０Ａ　シールド膜、３１，３５，４１，４２，４５　金属膜、４０Ａ，４０Ｂ，４０Ｃ　端子、５０　カバー膜、５０Ａ，５０Ｂ，５０Ｃ　開口部 1, 1A strain sensor, 10 film substrate, 10a upper surface, 20 strain detection element, 30, 30A shield film, 31, 35, 41, 42, 45 metal film, 40A, 40B, 40C terminal, 50 cover film, 50A, 50B , 50C opening

Claims (5)

  1. 　フィルム基板と、
    　前記フィルム基板の上面に形成された歪み検出素子と、
    　平面視、前記歪み検出素子と離間して前記歪み検出素子の周辺を囲うシールド膜と、を有する、歪みセンサ。     a film substrate;
    a distortion detection element formed on the upper surface of the film substrate;
    A strain sensor, comprising: a shield film that surrounds the strain detection element while being spaced apart from the strain detection element in plan view.
  2. 　前記シールド膜は、前記歪み検出素子と同一の材料で形成されている、請求項１に記載の歪みセンサ。 The strain sensor according to claim 1, wherein the shield film is made of the same material as the strain detection element.
  3. 　前記シールド膜は、前記歪み検出素子よりもインピーダンスの低い材料で形成されている、請求項１に記載の歪みセンサ。 The strain sensor according to claim 1, wherein the shield film is made of a material having impedance lower than that of the strain detection element.
  4. 　前記シールド膜は、
    　第１金属膜と
    　前記第１金属膜の上面に形成された、前記第１金属膜よりもインピーダンスの低い材料で形成された第２金属膜と、を有する、請求項１に記載の歪みセンサ。     The shield film is
    2. The strain sensor according to claim 1, comprising: a first metal film; and a second metal film formed on an upper surface of said first metal film and made of a material having impedance lower than that of said first metal film.
  5. 　前記歪み検出素子は、Ｃｒを含む金属膜であり、
    　前記シールド膜は、Ｃｕを含む金属膜を有する、請求項１、３、又は４に記載の歪みセンサ。     The strain sensing element is a metal film containing Cr,
    5. The strain sensor according to claim 1, wherein said shield film has a metal film containing Cu.
PCT/JP2022/000343 2021-01-28 2022-01-07 Strain sensor WO2022163324A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0835808A (en) * 1994-02-15 1996-02-06 Hottinger Baldwin Messtech Gmbh Strain gauge and manufacture of strain gauge and measurement-quantity transmitter
JP2005114443A (en) * 2003-10-06 2005-04-28 Hitachi Ltd Device for measuring mechanical quantity

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0835808A (en) * 1994-02-15 1996-02-06 Hottinger Baldwin Messtech Gmbh Strain gauge and manufacture of strain gauge and measurement-quantity transmitter
JP2005114443A (en) * 2003-10-06 2005-04-28 Hitachi Ltd Device for measuring mechanical quantity

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