Temperature sensor

Abstract

To provide a temperature sensor that can suppress the thermal effects on the connection part of the lead wire. [Solution] The device comprises a strip-shaped flexible substrate 2 positioned directly above the object to be measured H with the lower surface of its tip portion 2a in contact with the object to be measured, a thermal element 3 installed on the upper surface of the tip portion, a pair of lead wires 7 connected to the base end portion 2b of the flexible substrate, and a separating member 5 that provides an air layer A between at least a portion of the flexible substrate other than the tip portion and the object to be measured, thereby separating at least a portion of the base end portion from the object to be measured.

Description

Technical Field

[0001] The present invention relates to a sensitivity sensor provided with a heat-sensitive element on a flexible substrate.

Background Art

[0002] Conventionally, a temperature sensor in which a heat-sensitive element such as a thermistor element is mounted on a flexible substrate (FPC) is known. For example, Patent Document 1 describes a temperature sensor including a flexible substrate that is a resin film provided with a conductor pattern, a temperature measuring resistor element (heat-sensitive element) provided on the flexible substrate, and a coated lead wire connected to the conductor pattern by soldering.

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 the temperature sensor of Patent Document 1, when the entire sensor is attached to the measurement object, the flexible substrate directly contacts the measurement object that is the heat source, and the lead wire is also close to the measurement object at the connection part. Therefore, there are cases where the heat resistance of the soldering material or the like connecting the lead wire cannot be ensured due to the transmitted heat. In particular, when the connection part of the lead wire is installed directly above the measurement object, the heat of the measurement object easily transfers to the connection part, and in the case of a bonding material with low heat resistance, there is a risk of causing a connection failure at the connection part. On the other hand, as a countermeasure, when adopting a special high heat-resistant bonding material such as sintered Ag or Au / Sn solder, or when a limited bonding method such as welding or pressure bonding is required, there is a disadvantage of high cost. Furthermore, because heat from the thermal element and flexible substrate could easily escape to the outside through the lead wires and their connections directly above the object being measured, there was a risk of reduced measurement accuracy.

[0005] The present invention has been made in view of the aforementioned problems, and aims to provide a temperature sensor that can suppress the thermal effects on the connection portion of the lead wire. [Means for solving the problem]

[0006] To solve the above problems, the present invention employs the following configuration. Specifically, the temperature sensor according to the first invention is characterized by comprising: a strip-shaped flexible substrate whose entire body is positioned directly above the object to be measured and whose lower surface of the tip portion is in contact with the object to be measured; a heat-sensitive element installed on the upper surface of the tip portion; a pair of lead wires connected to the base end of the flexible substrate; and a separating member that provides an air layer between at least a portion of the flexible substrate other than the tip portion and the object to be measured, thereby separating at least a portion of the base end from the object to be measured.

[0007] This temperature sensor includes a separating member that creates an air layer between at least a portion of the flexible substrate (excluding the tip) and the object being measured, thereby separating at least a portion of the base end from the object being measured. As a result, heat from the object being measured, which is the heat source, is less likely to be directly transferred to the flexible substrate (excluding the tip) due to the insulating effect of the air layer. This allows for the use of materials such as solder with low heat resistance for the joining material connecting the lead wires at the base end, and also suppresses heat dissipation from the object being measured to the base end and lead wires, enabling highly accurate temperature measurement.

[0008] The temperature sensor according to the second invention is characterized in that, in the first invention, the separating member is an insulating sheet that is installed between the base end and the object to be measured and has lower thermal conductivity than the flexible substrate. In other words, in this temperature sensor, the separating member is placed between the base end and the object being measured and is an insulating sheet with lower thermal conductivity than the flexible substrate. Therefore, the insulating sheet further reduces the transfer of heat from the object being measured to the base end. In addition, the presence of the insulating sheet between the base end and the object being measured creates a height difference between the tip and the base end, forming an air layer between the tip and the base end that does not come into contact with the object being measured.

[0009] The temperature sensor according to the third invention is characterized in that, in the second invention, it comprises an insulating heat shrink tube that covers the connection portion between the base end and the pair of lead wires, and the heat insulating sheet is provided protruding from the lower surface of the heat shrink tube toward the tip. In other words, in this temperature sensor, the heat insulating sheet is provided so that it protrudes from the underside of the heat shrinkable tube toward the tip. As a result, the heat insulating sheet is also interposed between the heat shrinkable tube at the base and the tip, and a higher heat insulating effect can be obtained through both the air layer formed between the tip and the base and the heat insulating sheet.

[0010] The temperature sensor according to the fourth invention is characterized in that, in the first invention, the separating member is a bent or curved strip-shaped reinforcing plate that is bonded to the flexible substrate and holds at least a portion of the base end away from the object to be measured when the flexible substrate is bent. In other words, in this temperature sensor, the separating member is a bent or curved strip-shaped reinforcing plate that is bonded to the flexible substrate and holds at least a portion of its base end separated from the object to be measured when the flexible substrate is bent. Therefore, the reinforcing plate can be used to bend or curve the flexible substrate, allowing at least a portion of its base end to be separated from the object to be measured and held stably with an air layer in between.

[0011] The temperature sensor according to the fifth invention is characterized in that, in the first invention, the separating member is a spacer provided between the base end and the object to be measured, and has a protrusion that protrudes from the lower surface and makes point contact with the object to be measured. In other words, in this temperature sensor, the separation member is a spacer provided between the base end and the object to be measured, and has a protrusion that protrudes from the lower surface and makes point contact with the object to be measured. As a result, heat from the object to be measured is not easily transferred from the point-contacting protrusion, and an air layer can be formed between the lower surface of the separation member (which is the spacer) and the object to be measured.

[0012] The temperature sensor according to the sixth invention is characterized in that, in the first invention, it comprises a case member covering at least the upper part of the tip and an elastic member installed between the case member and the tip, wherein the elastic member biases the tip toward the object to be measured. In other words, in this temperature sensor, the elastic member biases the tip toward the object to be measured, allowing the tip to make more stable contact with the object.

[0013] The temperature sensor according to the seventh invention is characterized in that, in the sixth invention, the elastic member is a hollow tube. In other words, in this temperature sensor, the elastic member is a hollow tube, so it has a small heat capacity and heat from the tip is not easily transferred, thus minimizing the impact on the temperature measurement of the heat sensing element. [Effects of the Invention]

[0014] The present invention provides the following effects. In other words, the temperature sensor according to the present invention is equipped with a separating member that provides an air layer between at least a portion of the flexible substrate other than the tip and the object to be measured, thereby separating at least a portion of the base end from the object to be measured. As a result, the heat insulation effect of the air layer allows for the use of a bonding material with low heat resistance at the connection point of the lead wire, and prevents heat from escaping to the base end and lead wire, enabling highly accurate temperature measurement. Therefore, the temperature sensor of the present invention has excellent heat resistance and can be attached to objects that are being measured at high temperatures. [Brief explanation of the drawing]

[0015] [Figure 1] In the first embodiment of the temperature sensor according to the present invention, it is a side view showing the temperature sensor installed on the measurement object. [Figure 2] In the first embodiment, it is a perspective view showing the temperature sensor installed on the measurement object. [Figure 3] In the second embodiment of the temperature sensor according to the present invention, it is a side view showing the temperature sensor installed on the measurement object. [Figure 4] In the second embodiment, it is a perspective view (a) and a bottom view (b) showing the temperature sensor. [Figure 5] In the third embodiment of the temperature sensor according to the present invention, it is a side view showing the temperature sensor installed on the measurement object. [Figure 6] In the first embodiment, it is a perspective view showing the temperature sensor. [Figure 7] In the fourth embodiment of the temperature sensor according to the present invention, it is a perspective view showing the state (a) of the temperature sensor with the entire case member removed, the state (b) of the temperature sensor with only the upper surface of the case member removed, and the state (c) of the temperature sensor housed in the case member.

Mode for Carrying Out the Invention

[0016] Hereinafter, the first embodiment of the temperature sensor according to the present invention will be described with reference to FIGS. 1 and 2.

[0017] As shown in FIGS. 1 and 2, the temperature sensor 1 of the present embodiment includes a strip-shaped flexible printed circuit board (FPC) 2 that is entirely arranged directly above the measurement object H and has the lower surface of the tip portion 2a contacted on the measurement object H, a heat-sensitive element 3 installed on the upper surface of the tip portion 2a, a pair of lead wires 4 connected to the base end portion 2b of the flexible printed circuit board 2, and a separation member 5 that provides an air layer A between at least a part of the flexible printed circuit board 2 other than the tip portion 2a and the measurement object H and separates at least a part of the base end portion 2b from the measurement object H.

[0018] The separation member 5 is an insulating sheet with lower thermal conductivity than the flexible substrate 2, and is installed between the base end 2b and the object to be measured H. This separating member 5 is formed of, for example, a silicone sponge sheet or glass wool, which has a lower thermal conductivity than the epoxy resin of the flexible substrate 2. Furthermore, the temperature sensor 1 of this embodiment is equipped with an insulating heat-shrinkable tube 6 that covers the connection portion (not shown) between the base end 2b and the pair of lead wires 7. The heat-shrinkable tube 6 described above is formed in a flattened shape.

[0019] The flexible substrate 2 is attached to the object H to be measured by a double-sided adhesive sheet of thermal interface material (TIM), etc., with its leading edge 2a adhering to it. The separation member 5 of the above-mentioned heat-insulating sheet is adhered to the lower surface of the heat-shrinkable tube 6 and is provided to protrude from the lower surface of the heat-shrinkable tube 6 toward the tip portion 2a.

[0020] Therefore, when placed on the object to be measured H, a step is created between the tip portion 2a, which is adhered to the object to be measured H, and the base portion 2b, which is positioned directly above the object to be measured H, via the heat shrink tubing 6 and the separating member 5, and an air layer A is formed as a gap between the tip portion 2a and the base portion 2b of the flexible substrate 2. Therefore, as described above, the flexible substrate 2 between the tip portion 2a and the base portion 2b is separated from the object to be measured H via the air layer A and the separating member 5.

[0021] The above-mentioned heat-sensitive element 3 is, for example, a chip thermistor, and is sealed with a sealing resin 3a formed in a dome shape using epoxy resin or the like. Furthermore, a flake-type thermistor or a thin-film thermistor may be used as the thermal element 3.

[0022] The flexible substrate 2 described above has a pattern of copper foil or the like (not shown) formed on an insulating film such as epoxy resin. The tip of the pattern wiring is connected to the thermal element 3, and the base end is connected to the lead wire 7. The tip of the core wire (not shown) of the pair of lead wires 7 described above is connected to the pattern wiring with solder or metal paste. In particular, in this embodiment, solder is preferred as the joining material because it is low-cost and has a simple joining method.

[0023] As described above, the temperature sensor 1 of this embodiment is equipped with a separating member 5 that provides an air layer A between at least a portion of the flexible substrate 2 other than the tip portion 2a and the object to be measured H, thereby separating at least a portion of the base portion 2b from the object to be measured H. Therefore, heat from the object to be measured H, which is the heat source, is less likely to be directly transmitted to the flexible substrate 2 other than the tip portion 2a due to the heat insulation effect of the air layer A. This allows for the use of materials such as solder with low heat resistance in the joint material connecting the lead wires 7 at the base end 2b, and also suppresses heat dissipation from the object H being measured to the base end 2b and lead wires 7, enabling highly accurate temperature measurement.

[0024] Furthermore, since the separating member 5 is installed between the base end 2b and the object to be measured H and is an insulating sheet with lower thermal conductivity than the flexible substrate 2, the insulating sheet further reduces the transfer of heat from the object to be measured H to the base end 2b. In addition, the presence of the insulating sheet between the base end 2b and the object to be measured H creates a height difference between the tip end 2a and the base end 2b, allowing for the formation of an air layer A between the tip end 2a and the base end 2b that does not come into contact with the object to be measured H.

[0025] In particular, since the insulating sheet separation member 5 is provided protruding from the lower surface of the heat shrink tube 6 toward the tip 2a, the insulating sheet is also interposed between the heat shrink tube 6 at the base end 2b and the tip 2a. As a result, a higher insulating effect can be obtained through both the air layer A formed between the tip 2a and the base end 2b and the insulating sheet separation member 5.

[0026] Next, second to fourth embodiments of the temperature sensor according to the present invention will be described below with reference to Figures 3 to 7. In the following descriptions of each embodiment, the same reference numerals will be used for the same components described in the above embodiments, and their descriptions will be omitted.

[0027] The difference between the second embodiment and the first embodiment is that in the first embodiment, the separating member 5 is a heat insulating sheet, whereas in the second embodiment, as shown in Figures 3 and 4, the separating member 25 of the temperature sensor 21 is a bent or curved strip-shaped reinforcing plate that is bonded to the flexible substrate 2 and holds at least a portion of the base end 2b separated from the object to be measured H when the flexible substrate 2 is bent.

[0028] The separating member 25 in the second embodiment is, for example, a resin reinforcing plate made of epoxy resin or the like with a heat resistance of 200°C, which is bonded to the lower surface of the flexible substrate 2. The separation member 25 described above has a shape in which a portion of its middle section is bent or curved so as to hold at least a part of its base end 2b in a state where it is separated from the object to be measured H in advance. In the second embodiment, the heat-shrinkable tube (not shown) covering the base end 2b is covered with a mesh material 28 having low thermal conductivity and elasticity, such as a glass braided tube. The separating member 25 is bonded to the lower surface of the flexible substrate 2, extending from the tip portion 2a to the base portion 2b via a bent portion 25a, so that its base portion 2b and mesh material 28 extend diagonally with respect to the upper surface of the object H to be measured.

[0029] In other words, in the second embodiment, a step is created between the base portion 2b and the tip portion 2a due to the thickness of the heat shrink tubing and mesh material 28 covering the base portion 2b, and the separation member 25, which is a reinforcing plate, maintains the state in which the base portion 2b of the flexible substrate 2 extends diagonally upward toward the base. Therefore, when the tip portion 2a is adhered to the object to be measured H, only the tip side of the mesh material 28 is in contact with the object to be measured H, but the mesh material 28 on the base side is separated from the object to be measured H via the air layer A. Furthermore, the tip portion 2a of the flexible substrate 2 and the mesh material 28 are separated from the object to be measured H via an air layer A.

[0030] In the second embodiment, a rectangular heat collecting plate 27, which is a TIM sheet formed by Au flash plating or the like, is attached to the lower surface of the tip portion 2a and directly below the heat sensing element 3. In other words, with the heat collecting plate 27 in close contact with and adhered to the object H to be measured, the temperature sensor 21 of the second embodiment is attached to the object H to be measured. In Figure 4(b), the heat collector plate 27 and the separation member 25 are shown with hatching.

[0031] Thus, in the temperature sensor 21 of the second embodiment, the separating member 25 is a bent or curved strip-shaped reinforcing plate that is bonded to the flexible substrate 2 and holds at least a portion of the base end 2b separated from the object to be measured H when the flexible substrate 2 is bent. Therefore, the reinforcing plate (separating member 25) can bend or curve the flexible substrate 2, and at least a portion of the base end 2b can be held stably separated from the object to be measured H with an air layer A interposed between them.

[0032] Next, the difference between the third embodiment and the first embodiment is that in the first embodiment, the separating member 5 is a heat insulating sheet, whereas in the third embodiment, as shown in Figures 5 and 6, the separating member 35 of the temperature sensor 31 is a thin box-shaped spacer provided between the base end 2b and the object to be measured H. The separation member 35 of this third embodiment has a protrusion 35a that protrudes from the lower surface and makes point contact with the object H to be measured.

[0033] The separation member 35 is attached to the lower surface of the heat shrink tube 6 that covers the base end 2b, and is provided between the heat shrink tube 6 and the object to be measured H when the temperature sensor 31 is installed on the object to be measured H. The separating member 35 is formed from, for example, epoxy resin, into a hollow or solid thin box shape, and protrusions 35a are formed at each of the four corners of its lower surface. In other words, when the temperature sensor 31 is placed on the object to be measured H, only the four protrusions 35a come into contact with the object to be measured H, and an air layer A is formed between the lower surface of the separating member 35 and the object to be measured H. Furthermore, it is possible to form an even thicker air layer A by creating a recess on the lower surface of the separating member 35.

[0034] In the temperature sensor 31 of the third embodiment, the separation member 35 is a spacer provided between the base end 2b and the object to be measured H, and has a protrusion 35a that protrudes from the lower surface and makes point contact with the object to be measured H. Therefore, heat from the object to be measured H is not easily transferred from the point-contacting protrusion 35a, and an air layer A can be formed between the lower surface of the separation member 35, which is a spacer, and the object to be measured H.

[0035] Next, the difference between the fourth embodiment and the third embodiment is that in the third embodiment, the tip portion 2a is simply in contact with or attached to the object to be measured H, and the entire temperature sensor 31 is exposed, whereas the temperature sensor 41 of the fourth embodiment, as shown in Figure 7, comprises a case member 48 that covers at least the upper part of the tip portion 2a, and an elastic member 49 installed between the case member 48 and the tip portion 2a, the elastic member 49 biasing the tip portion 2a toward the object to be measured H.

[0036] The elastic member 49 described above is a hollow tube. For example, the elastic member 49 is formed by making a band of epoxy resin into a ring shape to form a tube. The case member 48 described above consists of a front end plate 49a positioned at the front end, side plates 49b positioned on both sides of the flexible substrate 2, and a top plate 49c that serves as a lid, and houses the entire flexible substrate 2 from the front end 2a to the base end 2b. In other words, the lower part of the case member 48 is open, allowing the tip portion 2a to be placed in contact with the object H to be measured.

[0037] Furthermore, the top plate 49c of the case member 48 covers the upper part from the tip portion 2a to the base portion 2b (including the heat shrink tube 6), and the upper surface of the elastic member 49 is pressed downward so as to bias the elastic member 49 installed on the tip portion 2a downward. Furthermore, it is preferable that the case member 48 is made of a material with high thermal insulation properties, such as a resin plate.

[0038] In this fourth embodiment of the temperature sensor 41, the elastic member 49 biases the tip portion 2a toward the object to be measured H, so that the elastic member 49 can bring the tip portion 2a into contact with the object to be measured H in a more stable and close state. Furthermore, because the elastic member 49 is a hollow tube, it has a small heat capacity and is less susceptible to heat transfer from the tip 2a, thus minimizing its impact on the temperature measurement of the heat-sensitive element 3.

[0039] It should be noted that the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. [Explanation of Symbols]

[0040] 1, 21, 31, 41…Temperature sensor, 2…Flexible substrate, 2a…Tip of flexible substrate, 2b…Base end of flexible substrate, 3…Thermal element, 5, 25, 35…Separating member, 6…Heat shrink tubing, 7…Lead wire, 35a…Protrusion of separating member, 48…Case member, 49…Elastic member, A…Air layer, H…Measurement target object

Claims

1. A strip-shaped flexible substrate is positioned directly above the object to be measured, with the lower surface of its tip in contact with the object to be measured. A heat-sensitive element is installed on the upper surface of the tip portion, A pair of lead wires connected to the base end of the flexible substrate, A temperature sensor characterized by comprising a separating member that provides an air layer between at least a portion of the flexible substrate other than the tip portion and the object to be measured, thereby separating at least a portion of the base end from the object to be measured.

2. In the temperature sensor according to claim 1, A temperature sensor characterized in that the separating member is an insulating sheet with lower thermal conductivity than the flexible substrate, which is installed between the base end and the object to be measured.

3. In the temperature sensor according to claim 2, An insulating heat-shrinkable tube is provided to cover the connection portion between the base end and the pair of lead wires. A temperature sensor characterized in that the heat insulating sheet is provided so as to protrude from the lower surface of the heat shrinkable tube toward the tip.

4. In the temperature sensor according to claim 1, A temperature sensor characterized in that the separating member is a bent or curved strip-shaped reinforcing plate that is bonded to the flexible substrate and holds at least a portion of the base end of the flexible substrate in a state separated from the object to be measured when the flexible substrate is bent.

5. In the temperature sensor according to claim 1, The temperature sensor is characterized in that the separation member is a spacer provided between the base end and the object to be measured, and has a protrusion that protrudes from the lower surface and makes point contact with the object to be measured.

6. In the temperature sensor according to claim 1, A case member covering at least the upper part of the tip, The case member and the tip portion are provided together, A temperature sensor characterized in that the elastic member biases its tip toward the object to be measured.

7. In the temperature sensor according to claim 6, A temperature sensor characterized in that the elastic member is a hollow tube inside.

Images