Temperature sensor

Abstract

To provide a temperature sensor in which an insulating film can be prevented from bending.SOLUTION: The present invention includes: an insulating film 2; a heat-sensitive element 3 provided in the front surface of the insulating film; a pair of wires 4 formed in the front surface of the insulating film, the wires being connected to the heat sensitive element at one end thereof and being connected to an external wire at another end; a front surface side cover layer 5 deposited on the front surface of the insulating film, the surface side cover layer being formed of an insulating material; and a back surface side cover layer 6 deposited on the back surface of the insulating film and formed of the same material as the material of the front surface side cover layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a temperature sensor capable of suppressing the occurrence of warpage.

Background Art

[0002] Conventionally, as a temperature sensor, a flexible temperature sensor has been used in which an insulating film such as a polyimide film is used as a substrate, and a heat-sensitive element such as a thin-film thermistor or a chip thermistor is provided on the surface thereof. For example, Patent Document 1 describes a temperature sensor including an insulating film, a thin-film thermistor portion formed of a thermistor material on the insulating film, and a pair of opposing electrodes connected to the thin-film thermistor portion and formed to face each other.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The following problems remain in the above conventional technology. That is, in a temperature sensor in which a heat-sensitive element is provided on an insulating film such as a polyimide film, there is a disadvantage that warpage is likely to occur due to the influence of heating or humidity. Since the insulating film is flexible, it can be flexibly installed on a curved surface or the like. On the other hand, since a heat-sensitive element is provided on the surface of the insulating film and a wiring pattern or the like is formed, the shrinkage coefficients on the front and back of the insulating film are different, and a phenomenon may occur in which it warps naturally during manufacturing or use. In particular, when a coverlay such as polyimide is laminated as a protective film on the surface of the insulating film, warpage is likely to occur.

[0005] The present invention has been made in view of the above-described problems, and an object thereof is to provide a temperature sensor capable of suppressing the occurrence of warpage in an insulating film.

Means for Solving the Problems

[0006] The present invention employs the following configuration to solve the above problems. That is, a temperature sensor according to a first invention includes an insulating film, a heat-sensitive element provided on the surface of the insulating film, a pair of wirings formed on the surface of the insulating film and having one end connected to the heat-sensitive element and the other end connected to a pair of external wirings, a surface-side cover layer laminated on the surface of the insulating film and formed of an insulating material, and a back-side cover layer laminated on the back surface of the insulating film and formed of the same material as the surface-side cover layer.

[0007] In this temperature sensor, since it includes a surface-side cover layer laminated on the surface of the insulating film and formed of an insulating material and a back-side cover layer laminated on the back surface of the insulating film and formed of the same material as the surface-side cover layer, by sandwiching the insulating film with the surface-side cover layer and the back-side cover layer of the same material, it is easier to set the shrinkage coefficients of the front and back to be the same compared to the case of only the surface-side cover layer laminated as a protective film, and it is possible to suppress the occurrence of warpage due to the influence of heating or humidity.

[0008] A temperature sensor according to a second invention is characterized in that, in the first invention, the surface-side cover layer and the back-side cover layer are formed of the same material as the insulating film. That is, in this temperature sensor, since the surface-side cover layer and the back-side cover layer are formed of the same material as the insulating film, good adhesive strength can be obtained because they are of the same material.

[0009] The temperature sensor according to the third invention, in the first or second invention, includes a heat collecting layer laminated on the back surface of the insulating film and directly below the heat sensitive element and formed of a material having a higher thermal conductivity than the insulating film, and the back surface side cover layer is formed so as to avoid the heat collecting layer and is set flush with the heat collecting layer or thinner than the heat collecting layer. That is, in this temperature sensor, since the back surface side cover layer is formed so as to avoid the heat collecting layer and is set flush with the heat collecting layer or thinner than the heat collecting layer, when the back surface side of the insulating film is installed facing the measurement object, the back surface side cover layer does not prevent the heat collecting layer from directly contacting the measurement object.

[0010] The temperature sensor according to the fourth invention, in any one of the first to third inventions, the insulating film is formed in a strip shape, and the pair of wirings includes a pair of main wiring portions extending parallel to each other in the extending direction of the insulating film, and a pair of element lands formed at one end side of the pair of main wiring portions and to which the heat sensitive element is soldered, and the heat sensitive element is a chip thermistor installed between one end side of the insulating film and the pair of main wiring portions, and the pair of element lands are formed to protrude from the middle of the pair of main wiring portions toward the heat sensitive element, and have an element side tapered portion whose width is gradually widened toward the main wiring portion between the portion where the heat sensitive element is adhered and the main wiring portion. That is, in this temperature sensor, since the pair of element lands are formed to protrude from the middle of the pair of main wiring portions toward the heat sensitive element and have an element side tapered portion whose width is gradually widened toward the main wiring portion between the portion where the heat sensitive element is adhered and the main wiring portion, when the insulating film is bent, the bending stress applied to the connection portion between the element land and the main wiring portion is smaller than in the case where the element land is connected in an L shape from the tip of the main wiring portion. In this way, by protruding the element land in a T shape and tapered shape from the middle of the main wiring portion via the element side tapered portion, in addition to the warpage prevention effect by the front surface side cover layer and the back surface side cover layer, wiring excellent in bend resistance (wire break resistance) can be obtained.

[0011] In the temperature sensor according to the fifth invention, in the fourth invention, the pair of wirings have a pair of external connection pad portions formed on the other end side of the pair of main wiring portions to which the external wiring is connected, and the main wiring portions are gradually widened toward the external connection pad portions and have external connection side tapered portions connected to the external connection pad portions. That is, in this temperature sensor, since the main wiring portion has an external connection side tapered portion that is gradually widened toward the external connection pad portion and is connected to the external connection pad portion, when the insulating film is bent, the bending stress applied to the connection portion with the external connection pad portion is smaller than when connected to the external connection pad portion with the same width. Therefore, in addition to the warpage prevention effect by the front surface side cover layer and the back surface side cover layer, wirings with better bend resistance (wire breakage resistance) can be obtained.

[0012] The temperature sensor according to the sixth invention is characterized in that, in any one of the first to fifth inventions, it includes a capacitor provided on the surface of the insulating film, connected to the pair of wirings, and electrically connected in parallel with the heat-sensitive element. That is, in this temperature sensor, since it includes a capacitor provided on the surface of the insulating film, connected to the pair of wirings, and electrically connected in parallel with the heat-sensitive element, the noise removal property can be improved by the bypass effect of the capacitor. Also, due to the above warpage prevention effect by the front surface side cover layer and the back surface side cover layer, it becomes difficult for stress due to warpage to be applied to the capacitor mounted on the surface of the insulating film.

Advantages of the Invention

[0013] According to the present invention, the following effects can be achieved. That is, according to the temperature sensor of the present invention, since it includes a front-side cover layer laminated on the surface of the insulating film and formed of an insulating material, and a back-side cover layer laminated on the back surface of the insulating film and formed of the same material as the front-side cover layer, by sandwiching the insulating film with the front-side cover layer and the back-side cover layer of the same material, it is easy to set the shrinkage coefficients of the front and back to be the same, and it is possible to suppress the occurrence of warping due to the influence of heating or humidity. Therefore, the temperature sensor of the present invention can suppress the phenomenon of naturally warping during manufacturing or use, and handling and the like become easy.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0015] Hereinafter, a first embodiment of the temperature sensor according to the present invention will be described with reference to FIGS. 1 to 3. In each of the drawings used in the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

[0016] As shown in FIGS. 1 to 3, the temperature sensor 1 of the present embodiment includes an insulating film 2, a heat-sensitive element 3 provided on the surface of the insulating film 2, and a pair of wirings 4 formed on the surface of the insulating film 2, one end of which is connected to the heat-sensitive element 3 and the other end of which is connected to a pair of external wirings. It also includes a surface-side cover layer 5 laminated on the surface of the insulating film 2 and formed of an insulating material, and a back-side cover layer 6 laminated on the back surface of the insulating film 2 and formed of the same material as the surface-side cover layer 5.

[0017] The surface-side cover layer 5 and the back-side cover layer 6 are formed of the same material as the insulating film 2. In the present embodiment, the insulating film 2 is a polyimide film (polyimide resin sheet), the surface-side cover layer 5 and the back-side cover layer 6 are formed of polyimide coverlay films, and are joined to the insulating film 2 by pressure bonding or an adhesive. The thicknesses of the surface-side cover layer 5 and the back-side cover layer 6 are appropriately set so that the shrinkage coefficients on the front and back of the insulating film 2 are the same.

[0018] The temperature sensor 1 of the present embodiment also includes a heat collecting layer 7 laminated on the back surface of the insulating film 2 and directly below the heat-sensitive element 3 and formed of a material having a higher thermal conductivity than the insulating film 2. The heat collecting layer 7 is pattern-formed in a rectangular shape by a metal layer such as a copper foil. The back-side cover layer 6 is formed avoiding the heat collecting layer 7 and is set flush with the heat collecting layer 7 or thinner than the heat collecting layer 7. In the present embodiment, the back-side cover layer 6 is set to be flush with the heat collecting layer 7.

[0019] The insulating film 2 is formed in a strip shape. The pair of wirings 4 includes a pair of main wiring portions 4a extending parallel to each other in the extending direction of the insulating film 2, and a pair of element lands 4b formed on one end side of the pair of main wiring portions 4a and to which the heat-sensitive element 3 is soldered. The above-mentioned heat-sensitive element 3 is a chip thermistor installed between one end side of the insulating film 2 and between a pair of main wiring portions 4a.

[0020] The pair of element land portions 4b are formed to protrude from the middle of the pair of main wiring portions 4a toward the heat-sensitive element 3, and have an element-side tapered portion 4c with a gradually widening width toward the main wiring portion 4a between the portion where the heat-sensitive element 3 is adhered and the main wiring portion 4a. The pair of wirings 4 have a pair of external connection pad portions 4d formed on the other end side of the pair of main wiring portions 4a to which external wirings are connected. The main wiring portion 4a has an external connection side tapered portion 4e formed with a gradually widening width toward the external connection pad portion 4d and connected to the external connection pad portion 4d.

[0021] The pair of wirings 4 are pattern-formed with, for example, copper foil or the like. The external connection pad portion 4d has a pad surface 4f for connecting an external wiring with a soldering material or the like. As the external wiring, a lead frame or a lead wire is used. The surface-side cover layer 5 is formed to cover the main wiring portion 4a on the insulating film 2 except at least the portion where the heat-sensitive element 3 of the element land portion 4b is adhered and the pad surface 4f.

[0022] Thus, in the temperature sensor 1 of this embodiment, since it includes the surface-side cover layer 5 formed of an insulating material laminated on the surface of the insulating film 2 and the back-side cover layer 6 formed of the same material as the surface-side cover layer 5 laminated on the back surface of the insulating film 2, by adopting a structure in which the insulating film 2 is sandwiched between the surface-side cover layer 5 and the back-side cover layer 6 of the same material, it is easier to set the shrinkage coefficients of the front and back to be the same compared to the case of only the surface-side cover layer 5 laminated as a protective film, and it is possible to suppress the occurrence of warping due to the influence of heating or humidity.

[0023] Also, since the surface-side cover layer 5 and the back-side cover layer 6 are formed of the same material as the insulating film 2, good adhesive strength can be obtained because they are of the same material. In addition, since the back-side cover layer 6 is formed while avoiding the heat collecting layer 7 and is set flush with the heat collecting layer 7 or thinner than the heat collecting layer 7, when the back side of the insulating film 2 is installed facing the measurement object, the back-side cover layer 6 does not prevent the heat collecting layer 7 from directly contacting the measurement object.

[0024] In addition, since the pair of element lands 4b are formed to protrude from the middle of the pair of main wiring parts 4a toward the heat-sensitive element 3 and have an element-side tapered part 4c whose width is gradually set wider toward the main wiring part 4a between the part where the heat-sensitive element 3 is adhered and the main wiring part 4a, when the insulating film 2 is bent, compared to the case where the element land 4b is connected in an L shape from the tip of the main wiring part 4a, etc., the bending stress applied to the connection part between the element land 4b and the main wiring part 4a becomes smaller. In this way, by protruding the element land 4b in a T shape and tapered shape from the middle of the main wiring part 4a via the element-side tapered part 4c, in addition to the warpage prevention effect by the front-side cover layer 5 and the back-side cover layer 6, a wiring excellent in bend resistance (wire break resistance) can be obtained.

[0025] Furthermore, since the main wiring part 4a has an external connection side tapered part 4e whose width is gradually formed wider toward the external connection pad part 4d and is connected to the external connection pad part 4d, when the insulating film 2 is bent, compared to the case where it is connected to the external connection pad part 4d with the same width, the bending stress applied to the connection part with the external connection pad part 4d becomes smaller. Therefore, in addition to the warpage prevention effect by the front-side cover layer 5 and the back-side cover layer 6, a wiring more excellent in bend resistance (wire break resistance) can be obtained.

[0026] Next, a second embodiment of the temperature sensor according to the present invention will be described below with reference to FIG. 4. In the description of the following embodiments, the same components described in the above embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

[0027] The difference between the second embodiment and the first embodiment is that in the first embodiment, only the heat-sensitive element 3 is mounted on the surface of the insulating film 2, whereas in the temperature sensor 21 of the second embodiment, as shown in FIG. 4, a capacitor C is provided on the surface of the insulating film 2 and connected to a pair of wirings 4, and is electrically connected in parallel with the heat-sensitive element 3. In the second embodiment, a surface-mounted small capacitor is mounted on the surface of the insulating film 2, and both ends are connected to the middle of a pair of main wiring portions 4a.

[0028] Thus, in the temperature sensor 21 of the second embodiment, since a capacitor C is provided on the surface of the insulating film 2 and connected to a pair of wirings 4 and is electrically connected in parallel with the heat-sensitive element 3, the noise removal performance can be improved by the bypass effect of the capacitor C. Note that the frequency of the noise changes due to the attenuation resonance between the capacitance of the capacitor C and the reactance L of the pair of wirings 4, and thus the capacitor C is installed at a position corresponding to the frequency of the noise. For example, the capacitor C of the second embodiment is arranged near the heat-sensitive element 3 and directly above the heat collecting layer 7 on the back surface of the insulating film 2. Further, due to the above-described warpage prevention effect by the front surface cover layer 5 and the back surface cover layer 6, it becomes difficult for stress due to warpage to be applied to the capacitor C mounted on the surface of the insulating film 2.

[0029] Note that the technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, although the above-described heat-sensitive element employs a chip-shaped thermistor element, a flake-shaped thermistor element, a thin film thermistor, or the like may be employed as the heat-sensitive element.

Explanation of Reference Numerals

[0030] 1, 21… Temperature sensor, 2… Insulating film, 3… Heat-sensitive element, 4… Wiring, 4a… Main wiring part, 4b… Land part for element, 4c… Taper part on the element side, 4d… External connection pad part, 4e… Taper part on the external connection side, 5… Surface-side cover layer, 6… Back-side cover layer, 7… Heat-collecting layer, C… Capacitor

Claims

1. An insulating film, a heat-sensitive element provided on the surface of the insulating film, a pair of wirings formed on the surface of the insulating film, one end of which is connected to the heat-sensitive element and the other end of which is connected to a pair of external wirings, a surface-side cover layer laminated on the surface of the insulating film and formed of an insulating material, a back-side cover layer laminated on the back surface of the insulating film and formed of the same material as the surface-side cover layer, a heat collecting layer laminated on the back surface of the insulating film and directly below the heat-sensitive element and formed of a material having a higher thermal conductivity than the insulating film, A temperature sensor, wherein the back-side cover layer is formed so as to avoid the heat collecting layer and is flush with the heat collecting layer or is set to be thinner than the heat collecting layer.

2. The temperature sensor according to claim 1, wherein the surface-side cover layer and the back-side cover layer are formed of the same material as the insulating film.

3. An insulating film, a heat-sensitive element provided on the surface of the insulating film, a pair of wirings formed on the surface of the insulating film, one end of which is connected to the heat-sensitive element and the other end of which is connected to a pair of external wirings, a surface-side cover layer laminated on the surface of the insulating film and formed of an insulating material, a back-side cover layer laminated on the back surface of the insulating film and formed of the same material as the surface-side cover layer, the insulating film is formed in a strip shape, the pair of wirings includes a pair of main wiring portions that extend parallel to each other in the extending direction of the insulating film, a pair of element land portions formed on one end side of the pair of main wiring portions and to which the heat-sensitive element is soldered, the heat-sensitive element is a chip thermistor installed between one end side of the insulating film and the pair of main wiring portions, A temperature sensor, wherein the pair of element land portions protrude from the middle of the pair of main wiring portions toward the heat-sensitive element and have an element-side tapered portion whose width is gradually widened toward the main wiring portion between the portion to which the heat-sensitive element is adhered and the main wiring portion.

4. The temperature sensor according to claim 3, wherein the pair of wirings has a pair of external connection pad portions formed on the other end side of the pair of main wiring portions and to which the external wiring is connected. The temperature sensor is characterized in that the main wiring portion has an external connection side tapered portion that is gradually widened toward the external connection pad portion and is connected to the external connection pad portion.

5. An insulating film, a heat-sensitive element provided on the surface of the insulating film, a pair of wirings formed on the surface of the insulating film, one end of which is connected to the heat-sensitive element and the other end of which is connected to a pair of external wirings, a surface-side cover layer laminated on the surface of the insulating film and formed of an insulating material, and a back-side cover layer laminated on the back surface of the insulating film and formed of the same material as the surface-side cover layer. The temperature sensor is characterized in that a capacitor is provided on the surface of the insulating film, connected to the pair of wirings, and electrically connected in parallel with the heat-sensitive element.

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