JP2006066751A - Temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable temperature sensor wherein it is prevented that the joining portions of the electrode portions of a thermistor element to the core-wires of its wires having insulation coatings are so expanded and so contracted by the temperature variation generated in its real using time as to peel slightly its electrode portions from the joining portions, and as to variate its resistance value. <P>SOLUTION: The thermistor element is so mounted previously on lands comprising conductive foils whose patterns are formed on an insulation substrate, and is so connected electrically with the lands as to create a sensor substrate. Then, the core-wires of parallel wires having insulation coatings are so connected respectively with output-terminal portions comprising the conductive foils as to form a temperature sensor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement in a temperature sensor for temperature detection in which a thermistor element is attached to the tip of an insulation-coated electric wire used in home electric products such as air conditioners and refrigerators and temperature control devices for various electronic devices.

  Conventionally, as shown in FIGS. 9 (a) and 9 (b), a temperature sensor having a thermistor element attached to the tip of an insulation-coated wire used in home appliances and various electronic devices has electrodes on both sides. A thermistor chip 10 or an SMD type thermistor element 11 having terminal electrodes at both ends in the longitudinal direction of a rectangular parallelepiped shape is sandwiched between the exposed core wires 14 by peeling off the insulation coating at the end of the two-core parallel insulation coated electric wire 13. After that, it was manufactured by soldering by means such as dipping in a solder bath and connecting and fixing to the core wire of the insulation coated electric wire. After the thermistor element is connected and fixed to the core wire at the tip of the insulation-coated electric wire, an insulating material 15 such as epoxy resin is applied around the thermistor element at the tip and is cured by heating to complete the temperature sensor. Alternatively, after the thermistor element is connected and fixed to the core wire at the end of the insulation-coated wire, the end is inserted into a bottomed pipe made of metal or resin, and an insulating material such as epoxy resin is injected around it and cured by heating. A temperature sensor has been completed (for example, JP-A-10-270208).

  However, in the temperature sensor in which the thermistor chip 10 and the thermistor element 11 having electrodes formed on both surfaces as described above are sandwiched between the core wires 14 of the insulation coated electric wire 13, the core wire of the insulation coated electric wire is directly attached to the electrode surface 16 of the thermistor chip. 14 is soldered, the resistance value of the thermistor chip 10 and the thermistor element 11 changes due to the silver erosion phenomenon in which the electrode surface 16 mainly composed of silver is melted by the solder, and the product yield of the completed temperature sensor is lowered. There were drawbacks. Moreover, when the thickness of the electric wire to be used is changed, the distance between the core wires changes, so that the thermistor chip 10 and the thermistor element 11 can be sandwiched so that a process for changing the dimensions between the core wires is required. There are increasing drawbacks. Further, when soldering the thermistor chip that has been sandwiched in a solder bath, the chip may drop off due to insufficient clamping force, producing a temperature sensor that is not connected to the thermistor chip, and defective products are likely to occur. 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.

  A temperature sensor has also been proposed in which an SMD type thermistor element 11 having terminal electrodes at both ends in the longitudinal direction of a rectangular parallelepiped shape shown in FIG. Since the electrode portion 16 has a curved surface, it is necessary to process the exposed core wire portion in order to be sandwiched between the core wires 14, and there is a disadvantage that the number of man-hours increases as in the conventional example. Further, the terminal electrode portion 16 of the SMD type thermistor element 11 is generally provided with a measure against silver erosion, but in the case where the core wire is directly soldered to the electrode, the thermistor chip is used. When the product is used for a long time, the resistance of the thermistor element may be exfoliated and the resistance value may change due to the expansion / contraction of the used member such as the insulated wire due to temperature change. There was a problem in terms of reliability.

  In addition, the temperature sensor in which the thermistor chip or thermistor element is directly soldered to the core wire part of the insulation-coated wire in this way, the heat received by the thermistor chip or the thermistor element escapes from the soldered part to the core wire of the insulation-coated wire. Therefore, it is difficult to accurately detect the temperature of the detection object with the thermistor chip or the thermistor element. If the shape of the thermistor chip or the thermistor element is reduced in order to enhance the responsiveness as a temperature sensor, it becomes more difficult to accurately detect the temperature of the detection object for the above reasons.

  The present invention has been made to solve the above-described problems, and is provided at one end between two conductor foils patterned on an insulating substrate made of a glass epoxy copper clad laminate, a polyimide resin film, or the like. A thermistor element is electrically joined and a sensor substrate having an output terminal portion formed at the other end is prepared, and the insulation coating at one end portion of the two-core parallel insulation coated electric wire is peeled off from the output terminal portion of the sensor substrate. It is an object of the present invention to provide a highly reliable temperature sensor that is small in size, excellent in temperature responsiveness, and small in change over time by electrically connecting the exposed core wires by means such as soldering.

  The present invention has been made to achieve the above object, and the invention of claim 1 includes an insulating substrate and an output terminal portion formed at one end of two conductor foils formed on the insulating substrate. The output of the sensor substrate comprising: a lead portion extending from the output terminal portion; a land formed on the other end side of the conductor foil through the lead portion; and a thermistor element connected to the land. The temperature sensor is characterized in that the exposed core wire portion of the insulating coated electric wire is electrically connected to the terminal portion.

  The invention according to claim 2 of the present invention uses, as the thermistor element, a thin film thermistor element in which an electrode part is formed on one side or a surface-mount type chip thermistor having terminal electrodes at both ends in the longitudinal direction of a rectangular parallelepiped shape. The temperature sensor according to claim 1.

  The invention according to claim 3 of the present invention is characterized in that the lead portion connecting the land and the output terminal portion is formed of a conductor foil having a narrow line width. It is.

  The invention according to claim 4 of the present invention is characterized in that an opening is provided on the insulating substrate excluding a conductor foil portion formed of lands, lead portions and output terminal portions formed on the insulating substrate. 3 is a temperature sensor.

  A sensor substrate in which a thermistor element is electrically connected to a land provided at one end on an insulating substrate on which two conductor foils are formed and an output terminal portion is formed on the other end of the conductor foil is prepared in advance. A thermistor element is mounted by electrically connecting the output terminal portion of the sensor board and the exposed core wire by peeling off the insulation coating at one end of the two-core parallel insulation coated wire by means of soldering or the like. The electrical characteristics can be inspected in the state of the sensor substrate, and only the non-defective sensor substrate can be used, so that the yield can be improved and the temperature sensor can be efficiently manufactured.

  By preparing sensor substrates having different pattern intervals of the output terminal portions, it becomes possible to manufacture temperature sensors corresponding to various 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 lead part connecting the land of the two conductor foils formed on the sensor substrate and the output terminal part as narrow as possible, and placed on the land. By making it difficult for the heat received by the fixed thermistor chip or thermistor element to be dissipated to the output terminal side, a temperature sensor with excellent thermal response can be manufactured.

  By providing an opening on the insulating substrate excluding the conductor foil portion composed of lands, leads, and output terminals formed on the insulating substrate, the heat capacity of the sensor substrate on which the thermistor element is mounted can be reduced, and further the thermistor element Since the heat capacity of the tip portion on which is mounted can be reduced, the thermal response as a temperature sensor can be further improved.

  By using the sensor substrate, it is possible to prevent the electrode portion of the thermistor element from peeling off due to the expansion and contraction of the insulated wire due to a thermal shock such as a rapid change or periodic change of the ambient temperature as in the past. Thus, a highly reliable temperature sensor can be provided at a low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a plan view of an insulating substrate used in the temperature sensor of the present invention. As the insulating substrate 2, a flexible substrate in which a copper foil is stretched on the surface such as a glass epoxy copper clad laminate or a polyimide resin film can be used. The land 4 for electrically connecting the output terminal portion 3, the lead portion 6, and the thermistor element 5 is formed by etching the copper foil on the surface. The lead part 6 connecting the land 4 and the output terminal part 3 is as much as possible so that the heat received by the thermistor element 5 from the detected body does not escape through the output terminal part 3 to the core wire of the connected insulated coated electric wire. It is preferable to form the pattern with a narrow line width so that the thermal resistance is increased. The dimensions of the insulating substrate used in this example were 2.2 × 2.4 × 0.1 mm glass epoxy copper clad laminates. The line width of the lead portion was 100 to 200 microns.

  FIG. 2A shows a perspective view of the sensor substrate 1 on which the thermistor element 5 is mounted. 2B is a cross-sectional view taken along line XX, and FIG. 2C is a schematic diagram of the thermistor structure. The manufacturing procedure of the sensor substrate 1 is as follows. Solder paste is printed on the land 4 portion on the insulating substrate 2 by means of screen printing or the like, and the electrode portion 7 of the thin film thermistor element 5 is positioned and superimposed thereon, and the entire substrate is heated to melt the solder paste. The land 4 of the insulating substrate 2 and the electrode portion 7 of the thin film thermistor element 5 are electrically joined. Reference numeral 8 denotes a thermistor film. As shown in FIG. 3, the sensor substrate 1 is manufactured by etching a copper foil formed on a large piece of glass epoxy copper clad laminate 11 to produce an output terminal portion as shown in FIG. 3. A large number of lands 4 and lead portions 6 are formed at a time. Thereafter, as described with reference to FIG. 2, the thermistor element 5 is placed on the land 4 to which the solder paste is applied, and the electrode portion 7 of the thermistor element 5 and the land 4 are melted and electrically joined. . In this way, a single laminated board on which a large number of thermistor elements are mounted is in this state, inspected for the necessary electrical characteristics as a thermistor in air or oil, and then individually divided and cut to obtain only good products. The sensor substrate 1 is completed by sorting. Alternatively, as will be described later, if used after being cut into strips, automatic assembly is possible in the subsequent assembly process, and efficient production is possible.

  As shown in FIG. 4, the sensor substrate 1 completed in this manner is obtained by soldering the core wire portion 14 from which one end portion of the two-core parallel insulation covered electric wire 13 is exposed and the output terminal portion 3 of the sensor substrate 1. The temperature sensor 17 is completed by joining. FIG. 4 is an enlarged view of the tip of the temperature sensor.

  The temperature sensor 17 of the present invention is a temperature sensor having a structure in which a sensor substrate connected to the tip of an insulation-coated electric wire and a part of the insulation coating portion of the insulation-coated electric wire are dip-coated integrally with an insulating resin such as an epoxy resin. Or a temperature sensor having a structure in which an insulating resin is filled in by inserting it into a bottomed pipe made of metal, resin, or the like, can be shaped according to the intended use.

  FIG. 5 shows another pattern of the conductive foil of the insulating substrate, showing the insulating substrate in a meandering pattern for increasing the distance between the land 4 and the lead portion 6 connecting the output terminal portion 5, and the insulating substrate of FIG. As shown in the sectional view taken along the line B-B in FIG. 5B, the conductor foil of the output terminal portion is formed in a tab shape so that the core wire of the insulation-coated electric wire can be spot-welded. it can. FIG. 7 shows a sensor substrate on which a thermistor element is mounted by providing an opening 18 on the insulating substrate 2 excluding the conductor foil portion composed of the land 4, the lead portion 6 and the output terminal portion 3 formed on the insulating substrate 2. Since not only the heat capacity can be reduced, but also the heat capacity of the tip portion on which the thermistor element is mounted can be reduced, the thermal responsiveness as the temperature sensor can be further improved as compared with the structure of the above embodiment.

  FIG. 8 shows an example of a method for manufacturing the temperature sensor of the present invention. 7 is a strip-shaped substrate in which a large number of sets of output terminal portions 3, lead portions 6 and lands 4 made of conductive foil are formed on an insulating substrate 2, and the insulating substrate shown in FIG. A substrate formed so that the front end portion of the substrate has a curved shape is used. The shape of the substrate may be determined according to the intended use as described above. The thermistor element 5 is connected to the land of the strip-shaped substrate by means such as soldering, and then the core wire portion of the parallel insulation coated electric wire 13 and the output terminal portion 3 are connected by soldering, and the dotted line portion C is connected. Individual temperature sensors are completed by cutting. By using such a strip-shaped substrate, it is possible to automate the mounting and joining process of the thermistor element and the connecting process of the parallel insulation coated electric wires, and efficient production can be achieved.

It is a top view of the insulated substrate used for the temperature sensor of this invention. The perspective view and sectional drawing of the sensor board | substrate which mounted the thermistor element on the said insulated substrate, and the perspective view of the thin film thermistor element to be used are shown. FIG. 2 is a plan view showing an example of an insulating substrate in which a large number of lands, lead portions, and output terminal portions are formed on a single insulating substrate. The perspective view which shows the temperature sensor structure of this invention which connected the sensor board | substrate and the core wire of the insulation coating electric wire by soldering is shown. It is another example of an insulated substrate. It is another example of an insulated substrate. It is another example of an insulated substrate. An example of the manufacturing method of the temperature sensor of this invention is shown. The temperature sensor of a prior art example is shown.

Explanation of symbols

1 Sensor board 2 Insulating board 3 Output terminal part 4 Land 5 Thermistor element 6 Lead part

Claims (4)

  An insulating substrate, an output terminal portion formed at one end of two conductor foils formed on the insulating substrate, a lead portion extending from the output terminal portion, and the other end of the conductor foil via the lead portion The exposed core wire portion of the insulation-coated electric wire is electrically connected to the output terminal portion of the sensor substrate composed of the land formed on the side and the thermistor element connected to the land. Temperature sensor.   2. The temperature sensor according to claim 1, wherein the thermistor element is a thin film thermistor element in which an electrode part is formed on one side or a surface-mount type chip thermistor having terminal electrodes at both ends in the longitudinal direction of a rectangular parallelepiped shape. .   The temperature sensor according to claim 1, wherein a lead portion connecting the land and the output terminal is formed of a conductor foil having a thin line width. 4. The temperature sensor according to claim 1, wherein an opening is provided on the insulating substrate excluding a conductor foil portion including a land, a lead portion, and an output terminal portion formed on the insulating substrate.

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