JP2006090704A - Temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems as to a temperature sensor comprising a heat-sensitive element sealed in a pipe that a long insulation-coated wire to be led out makes it hard to hold an insulated electric wire at a center portion of the pipe when performing insulation resin sealing, resin hardens with the wire in contact with an edge of the pipe to cause resin material to be hardened in a spilt state from the pipe, it is hard to accurately position a heat-sensitive part of a thermistor element which has a defective shape or whose insulation-coated electric wire is connected to an end part of the pipe, and the defective shape or insufficient withstand voltage may cause many defective products. <P>SOLUTION: A sensor substrate is prepared with the heat-sensitive element previously mounted on its land made of conductor foil with a pattern formed thereon on an insulating substrate having a shape conformed to the shape of the pipe. After joining the core of the insulation-coated wire to a terminal part of the sensor substrate, the sensor substrate is inserted into the pipe and an insulating material is put in its surrounding space and hardened to form the temperature sensor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention seals a thermosensitive element such as a thermistor with an insulating resin at the tip of a pipe used for household appliances such as water heaters, air conditioners, refrigerators, etc., and temperature control devices for various electronic devices, etc. The present invention relates to a temperature sensor in which an insulation coated electric wire or the like is drawn from an end opening.

  Conventionally, as shown in FIG. 7A, a thermistor chip 25 having electrodes on both sides is used as a temperature sensor in which a thermistor element used in such home appliances and various electronic devices is enclosed in a pipe. The insulation coating at the end of the two-core parallel insulation-coated electric wire 9 is peeled off and placed between the exposed core wires 16, and then soldered to be connected and fixed to the core wire 16 of the insulation-coated electric wire 9. Or a temperature sensor that is inserted into a bottomed pipe 26 made of a resin and injected with an insulating material 27 such as an epoxy resin around the pipe and thermally cured, as shown in FIG. After connecting the lead wire 29 of the glass-sealed thermistor element 28 with the tip coated with glass between the exposed core wires by soldering or welding, the tip of the bottom is made of metal or resin. Insert into pipe 26 Temperature sensors insulating material 27 injected into the thermally cured such as epoxy resins are known to the surroundings. In some cases, in order to ensure insulation strength, the lead wire 29 of the glass-sealed thermistor element 28 may be covered with an insulating tube (not shown).

  However, the thermistor chip 25 having electrodes formed on both sides as described above is placed between the core wires 16 of the insulation-coated electric wire 9 and soldered, inserted into the bottomed pipe 26, and an insulating material such as epoxy resin around it. In general, in the temperature sensor in which 27 is injected and cured, the length of the insulated wire 9 drawn out from the pipe is much longer than the length of the bottomed pipe 26. When the bottomed pipe 26 is filled and cured, it is difficult to set so that the thermistor chip (heat-sensitive part) is accurately positioned at the tip of the bottomed pipe 26 because the long insulated wire 9 becomes an obstacle. . In addition, in order to eliminate such drawbacks, when the bottomed pipe 26 is made of metal, when a thermistor tip is positioned with a jig or the like so that the thermistor tip is positioned at the tip of the bottomed pipe, The surface of the thermistor chip 25 and the bottomed pipe 26 may come close to each other or may come into contact with each other, and the insulation withstand voltage between the surface of the thermistor chip 25 and the bottomed pipe 26 cannot be sufficiently obtained, resulting in a yield as a final product. There was a downside. Furthermore, in order to solder the core wire 16 of the insulation coated wire 9 directly to the electrode surface of the thermistor chip 25, the resistance value of the thermistor chip 25 changes due to the silver erosion phenomenon in which the electrode surface mainly composed of silver is melted by the solder. There is also a drawback that the product yield of the completed temperature sensor is lowered. In addition, since the diameter of the insulated wire is smaller than the diameter of the pipe and the drawn insulated wire is long, it is difficult to hold the insulated wire at the center of the bottomed pipe when sealing with insulating resin. The resin is heated and cured in such a manner that the insulated wire is in contact with the edge of the bottom pipe 26, the insulating resin is cured in a state where it spills from the pipe, and the thermistor element of the shape tip or the pipe tip as described above is formed. In some cases, the heat-sensitive part cannot be accurately positioned, and many defective products are generated.

  Also, such a temperature sensor is generally used in an atmosphere with a temperature change, and when used for a long period of time, this temperature change causes the thermistor soldered by the expansion / contraction of the used member of the insulated coated wire. There is a problem in terms of reliability because peeling of the electrode portion of the chip proceeds and the resistance value may change. Furthermore, moisture and moisture have entered from the core wire portion of the insulation-coated electric wire, and the thermistor chip connected to the tip portion of the core wire after long-term use may be affected by the moisture and moisture to deteriorate characteristics.

  In addition, the temperature sensor in which the thermistor chip is soldered directly to the core wire portion of the insulation-coated electric wire in this way, the heat received by the thermistor chip escapes from the soldered portion to the core wire of the insulation-coated electric wire, and the detected object It is difficult to detect temperature accurately. Further, as described above, the position of the thermistor chip serving as the heat sensitive portion in the bottomed pipe fluctuates, resulting in variations in response characteristics as a temperature sensor, which is not sufficient in terms of electrical performance. When the glass-sealed thermistor element 28 as shown in FIG. 7B is used, the above-mentioned problem of withstand voltage can be solved, but the same problem as in FIG.

  The present invention has been made to solve the above-described problems, and includes two lead portions patterned on a heat-resistant insulating substrate made of a glass epoxy copper-clad laminate, a polyimide resin film, or the like. A land formed at one end and a terminal portion formed on the other end side of the lead portion, and one end of a two-core parallel insulation coated electric wire on a terminal portion of a sensor substrate configured by electrically connecting a thermal element to the land The core part exposed by peeling off the insulation coating of the part is electrically connected by joining means such as soldering, and the sensor substrate is resin-sealed in the pipe, so that it is small and has excellent temperature response and electrical performance An object of the present invention is to provide a highly reliable temperature sensor with small variation and small change with time.

  The present invention has been made in order to achieve the above object, and the invention of claim 1 is a temperature sensor in which a sensor substrate having a heat-sensitive element mounted on an elongated insulating substrate is sealed in a pipe with an insulating material. A pair of lands formed at one end of the insulating substrate, a thermal element connected between the lands, a pair of terminal portions formed at the other end of the sensor substrate, and the lands and the terminal portions. A temperature sensor, comprising a lead portion to be connected, wherein a core wire portion where an insulation-coated electric wire is exposed is electrically connected to the terminal portion of the sensor substrate.

  The invention according to claim 2 of the present invention is the temperature sensor according to claim 1, wherein the shape of the insulating substrate is a shape along the wall surface of the pipe.

  According to a third aspect of the present invention, the thermosensitive element is a thin film thermistor element in which a thermistor thin film formed on one surface of a ceramic substrate, a pair of electrode portions, and gold bumps are formed on the pair of electrode portions. The temperature sensor according to claim 1 or 2, wherein:

  According to a fourth aspect of the present invention, in the sensor substrate, a cut portion is provided at an end portion of the insulating substrate on which the land is formed, and the thermal element is inserted and fixed in the cut portion, and the land and The temperature sensor according to claim 1, wherein the temperature sensor is electrically connected to the thermosensitive element.

  According to a fifth aspect of the present invention, there is provided a bottomed pipe having a flange made of an oxygen-free copper material, a sensor substrate having a shape along a wall surface of the bottomed pipe, and two leads on the sensor substrate. After ultrasonically bonding the gold-covered land formed at the tip of the part and the gold bump formed on the land and the electrode part of the thin film thermistor element, the insulation-coated electric wire is exposed to the terminal part of the sensor substrate. The temperature sensor according to any one of claims 1 to 4, wherein the core wires are joined, the sensor substrate is inserted into the bottomed pipe, and the periphery is sealed with an insulating resin.

  In the temperature sensor of the present invention, two lead portions made of conductive foil are formed on an elongated insulating substrate that can be inserted into a pipe, a land is provided at one end, and a terminal portion is provided at the other end. A sensor board in which a heat sensitive element such as a thermistor element is electrically connected to a land is prepared in advance, and the insulation is removed from the terminal part of the sensor board and one end of the two-core parallel insulation coated electric wire and exposed. The electrical characteristics can be inspected in the state of the sensor board on which the thermistor element etc. is mounted by electrically connecting the parts to each other by means of joining such as ultrasonic welding or soldering, and only non-defective sensor boards can be used. Therefore, the yield can be improved and the temperature sensor can be efficiently manufactured.

  By preparing an insulating substrate having different pattern intervals between terminal portions of the insulating substrate, it is possible to manufacture temperature sensors corresponding to various types of insulation-coated electric wires having different thicknesses that are used according to the intended use.

  Thermal resistance can be increased by forming the line width (pattern width) of the two lead parts made of conductive foil connecting the land formed on the sensor substrate and the terminal part as narrow as possible. By making it difficult for the heat received by the thermosensitive element such as the mounted thin film thermistor element to be dissipated from the terminal part to the core part of the insulation-coated electric wire, a temperature sensor with excellent thermal response can be manufactured.

  By making the shape of the sensor substrate along the wall surface of the bottomed pipe, when the insulating resin is filled and cured and sealed, the tip part where the thermal element on the sensor substrate is placed is at the bottom of the pipe The product yield can be improved because it can be accurately fixed and variation in electrical characteristics including thermal response as a completed temperature sensor can be reduced. In addition, when a metal pipe is used, the tip of the sensor substrate can be accurately fixed to the bottom of the pipe, so that there is no variation in the positional relationship between the thermal element and the pipe, and sufficient withstand voltage is obtained. The generation of defective products can be prevented and an improvement in yield can be expected. In addition, by using a sensor substrate with a thermal element mounted on an insulating substrate, even when manufacturing a temperature sensor with a long bottomed pipe, the tip of the sensor substrate with the thermal element mounted on the bottom of the pipe can be reliably and easily Since it can be installed and fixed on the machine, it is effective in preventing the occurrence of defective products and improving productivity.

  By using a sensor board with a shape along the wall of the bottomed pipe, the sensor board can be fixed to the center axis of the pipe when the sensor board is inserted into the pipe. It is not necessary to use a special jig for fixing the insulated coated electric wire so that it is positioned at the center of the pipe, and man-hours and working hours can be reduced.

  By using the sensor substrate used for the temperature sensor of the present invention, a thermal element such as a thermistor element due to the expansion / contraction of an insulation-coated electric wire generated by a thermal shock such as a rapid change or a periodic change of the ambient temperature as in the past. It is possible to prevent deterioration of the characteristics of the thermistor chip due to peeling of the electrode part and moisture / humidity entering from the core part of the insulating coated electric wire, and a highly reliable temperature sensor can be provided at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Fig.1 (a) shows the top view of the insulated substrate used for the temperature sensor of this invention. Reference numeral 1 denotes a heat-resistant insulating substrate in which a copper foil is stretched on the surface of a flexible substrate such as a glass epoxy copper-clad laminate or a polyimide resin film, and has an elongated shape so that it can be inserted into a pipe. By etching the copper foil on the surface of the insulating substrate 1, the land 4 for electrically connecting the terminal portion 2, the lead portion 3, and the thermal element is formed. The lead part 3 connecting the land 4 and the terminal part 2 has a thermal resistance as large as possible so that the heat received by the thermosensitive element from the detected object does not escape through the terminal part to the core part of the insulated wire. It is preferable to form a pattern with a narrow line width. In order to increase the thermal resistance, the pattern may be designed so that the distance between the land 4 and the terminal portion 2 is long. For the insulating substrate 1 of this example, a polyimide resin film having a thickness of 0.1 mm was used. The minimum line width of the lead portion 3 was 100 to 200 microns. In addition to the above, a ceramic substrate such as alumina can be used as the insulating substrate 1 as long as heat resistance is required. FIG. 1B is a plan view of the sensor substrate 6 in which the thermal element 5 is placed between the lands 4 of the insulating substrate 1, and an electrode portion (not shown) of the thermal element 5 and the land 4 are electrically joined.

  FIG. 2A shows an internal perspective view of a temperature sensor for detecting the water temperature of a water heater as an embodiment of the temperature sensor of the present invention, in which a sensor substrate 6 is arranged in a bottomed pipe 7. FIG. 2B is a cross-sectional view taken along line AA of a plane parallel to the axis of the bottomed pipe of FIG. The temperature sensor of the present embodiment is a sensor substrate in which a thin film thermistor element 11 is mounted and connected as a thermal element 5 between lands 4 of an insulating substrate 1 in a bottomed pipe 7 made of an oxygen-free copper material having a flange 8. 6 is inserted, and the insulation-coated electric wire 9 connected to the terminal portion 2 is drawn out from the bottomed pipe 7. The gap in the bottomed pipe 7 is sealed with an insulating resin 10. FIG.2 (c) shows the sectional view on the AA line of the front-end | tip part of the temperature sensor of this invention.

  The manufacturing procedure of the sensor substrate 6 used in the above embodiment is as follows. As shown in FIG. 2B, the insulating substrate 1 has substantially the same shape as the inner cross-sectional shape of the bottomed pipe 7, and the land 4 on the insulating substrate 1 is partially plated with gold (Au). 14 is formed. On the other hand, a gold bump 13 is formed on the electrode portion 12 of the thin film thermistor element 11 used as the heat sensitive element 5. The thin film thermistor 11 is positioned and superposed on the land 4, and pressure is applied to the thin film thermistor element 11 to bond the bump 13 to the land portion by applying ultrasonic vibration. In addition, joining time can be shortened by applying ultrasonic vibration, heating a junction part at about 100-200 degreeC. FIG. 2D is a perspective view showing the appearance of the thin film thermistor element. The thin film thermistor element 11 includes a thermistor thin film 15 on a ceramic substrate 18, electrode portions 12 formed at both ends, and gold bumps 13 formed on the electrode portions 12. The sensor substrate 6 completed by mounting the thin film thermistor element 11 on the insulating substrate 1 is a core wire in which the terminal portion 2 and one end portion of the insulated coated electric wire 9 are exposed as shown in FIGS. 2 (a) and 2 (b). The temperature sensor 17 for a hot water heater is completed by joining the part 16 by means such as ultrasonic welding, inserting it into the bottomed pipe 7, filling the gap with the insulating resin 10, and curing it. FIG. 2 (c) shows a cross-sectional view of the tip portion of FIG. 2 (a) along the line B-B in the above embodiment, in which the tip portion of the bottomed pipe 7 constituting the temperature sensor has a flat shape. This is because when the sensor substrate 6 is inserted into the bottomed pipe 7, the distance between the ceramic substrate 18 of the thin film thermistor element 11 placed on the tip of the sensor substrate 6 and the wall surface of the bottomed pipe 7 is made closer. The heat transfer from the thin film thermistor element 11 to the thin film thermistor element 11 is improved to improve the response characteristics.

  In addition, as another manufacturing method of the temperature sensor of the present invention, for example, a copper foil on a single insulating substrate formed continuously as shown in FIG. 3 are formed at a time, and then a plated film 14 is formed on the land 4 by gold plating, and then the gold bumps 13 formed on the electrode portions 12 of the thin film thermistor element 11 and the lands 4 are pressed against each other. Join by applying sonic vibration. In this way, a single connected sensor substrate on which many thin film thermistor elements 11 are mounted is completed. Thereafter, the core wire portion 16 and the terminal portion 2 of the insulation-coated electric wire 9 are joined by means such as ultrasonic welding, and the insulation-coated electric wire is attached by dividing and cutting individually by cutting along the dotted line portion C. The sensor substrate 6 is completed. By using such a strip-shaped substrate, it is possible to automate the mounting and joining process of the thin film thermistor element and the connection process of the insulated coated electric wire, and efficient production can be achieved.

  Although the temperature sensor of the present invention disclosed in the above embodiment has been described with respect to a method in which a gold bump is provided on the electrode portion of the thin film thermistor element and the land of the sensor substrate is joined by ultrasonic waves, the present invention is not limited thereto. Of course, a generally used soldering method may be used depending on the atmosphere and temperature used as the temperature sensor, and may be appropriately selected according to the purpose of use. The same applies to the connection means between the terminal portion of the sensor substrate and the insulated wire.

  In the present embodiment, the structure in which the thin film thermistor element is placed and fixed on the land on the insulating substrate is shown. However, as shown in FIG. The thin-film thermistor element 11 is placed and fixed on the sensor board terminal portion of the sensor substrate in which the electrode portion 12 of the thin-film thermistor element 11 and the land 4 of the insulating substrate 1 are connected to each other by means of bonding such as a wire 20. After joining the parts by means of soldering or welding, etc., if the sensor board and a part of the insulation-coated electric wire are inserted into the pipe and the surrounding void is sealed and fixed with insulating resin, the tip of the sensor board Since it can be fixed closer to the heat sensitive part at the bottom of the pipe, not only can the temperature of the object to be detected be accurately detected, but also heat transfer from the pipe wall surface can be accelerated. Improvement of the properties can be expected.

   4 and 5 show other shapes of the insulating substrate used. FIG. 4A shows an example in which a hole 21 is provided in the terminal portion 2 of the insulating substrate 1. Depending on the intended use, as a connection method between the terminal portion 2 of the insulating substrate 1 and the core wire portion 16 of the insulated wire 9, the joining strength of the joint portion may be used in joining means such as soldering or welding as shown in the above embodiment. May not be sufficient. At this time, as shown in FIG. 4 (b), the core wire portion 16 of the insulation covered electric wire 9 is inserted into the hole portion 21 to be entangled and fixed, or as shown in FIG. 5 (a), the terminal of the insulating substrate 1 is fixed. The insulating substrate 1 provided with the recess 22 in the portion 2 is used, and the core wire portion 16 of the insulation coated electric wire 9 is fitted into the recess 22 provided in the terminal portion 2 portion of the insulating substrate 1 as shown in FIG. If it is fixed and soldering or the like is performed as necessary, the sensor substrate and the insulated coated electric wire can be connected more firmly. The shape of the insulating substrate described above is not limited to the shape along the wall surface of the pipe shown in the above-described embodiment, and is particularly a sensor substrate on which a thermal element is mounted according to the cross-sectional shape of the pipe to be inserted. It is preferable to design the shape so that the front end of the can be securely installed and fixed to the bottom of the pipe.

1A and 1B are plan views of an insulating substrate and a sensor substrate used in the temperature sensor of the present invention. FIG. 2A shows an internal perspective view of a temperature sensor that detects the water temperature of a water heater as an embodiment of the temperature sensor of the present invention. 2B is a cross-sectional view taken along the line AA, FIG. 2C is a cross-sectional view taken along the line BB, and FIG. 2D is a perspective view showing a schematic configuration of the thin film thermistor element used. It is. FIG. 3 is a plan view of a continuously formed sensor substrate showing a state in which a plurality of sensor substrates each having a thermal element mounted thereon are connected on an insulating substrate, and an insulating coated electric wire is connected to each sensor substrate. Show. FIG. 4A is a plan view showing another shape of the insulating substrate, and FIG. 4B is a side view when the insulated coated electric wire is connected using the insulating substrate. Fig.5 (a) is a top view which shows the other shape of an insulated substrate, FIG.5 (b) shows the side view when an insulated covering electric wire is connected using the insulated substrate. FIG. 6 is a partial perspective view showing a state in which a cut portion is provided at the tip of the insulating substrate, and a thermal element is inserted and fixed in the cut portion. FIG. 7 is a conventional temperature sensor. FIG. 7A is a cross-sectional view of a thermistor chip directly connected to an insulated coated wire and resin-sealed on a pipe. FIG. Sectional drawing of what sealed the resin which sealed the thermistor element to the pipe is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation board 2 Terminal part 3 Lead part 4 Land 5 Thermal element 6 Sensor board 7 Bottomed pipe 9 Insulated coated electric wire 10 Insulating material 11 Thin film thermistor element 13 Gold bump 15 Thermistor thin film 17 Temperature sensor for water heater

Claims (5)

  In a temperature sensor in which a sensor substrate having a heat-sensitive element mounted on an elongated insulating substrate is sealed with an insulating material in a pipe, a pair of lands each having the insulating substrate formed at one end, and a heat-sensitive element connected between the lands And a pair of terminal portions formed at the other end of the sensor substrate, and lead portions connecting the lands and the terminal portions, wherein the sensor substrate is insulated from the terminal portions. A temperature sensor, wherein the exposed core wire portion of the covered electric wire is electrically connected.   The temperature sensor according to claim 1, wherein a shape of the insulating substrate is a shape along a wall surface of the pipe.   The thermosensitive element is a thin film thermistor element in which a thermistor thin film formed on one surface of a ceramic substrate, a pair of electrode portions, and gold bumps are formed on the pair of electrode portions. 2. The temperature sensor according to 2.   In the sensor substrate, a cut portion is provided at an end portion of the insulating substrate on which the land is formed, the thermal element is inserted and fixed in the cut portion, and the land and the thermal element are electrically connected. The temperature sensor according to claim 1, 2, or 3. A bottomed pipe having a flange made of an oxygen-free copper material, a sensor substrate having a shape along the wall surface of the bottomed pipe, and a gold-coated land formed at the tips of two lead portions on the sensor substrate And ultrasonic bonding the land and the gold bump formed on the electrode portion of the thin film thermistor element, and then bonding the exposed core wire portion to the terminal portion of the sensor substrate, 5. The temperature sensor according to claim 1, wherein the sensor substrate is inserted into a pipe and the periphery is sealed with an insulating resin.

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