JP2014170772A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature sensor not susceptible to the effect of an ambient humidity and capable of highly accurate temperature detection.SOLUTION: The temperature sensor comprises a thermistor member 2, a pair of terminal electrode members 3 oppositely disposed at both ends of the thermistor member and touching both ends, and an insulating pipe 4 having the pair of terminal electrode members at opposite ends and sealing the thermistor member in the interior together with an inert gas, the thermistor member being of a chip shape having a thermistor element assembly 5 formed with a thermistor material and a pair of terminal parts 6 formed at both ends of the thermistor element assembly and constituting an electrode, and the terminal electrode members having, on a central axis, a convex-shaped electrode part 3a protruding into the interior via a space between the insulating pipe and themselves and abutting on the terminal part.

Description

  The present invention relates to a temperature sensor capable of detecting temperature with high accuracy without being affected by ambient humidity.

Conventionally, as a temperature sensor using a thermistor element, for example, Patent Document 1 has a thermistor chip, a pair of electrode layers formed on the thermistor chip, and a pair of lead wires connected to these electrode layers. A glass-sealed thermistor element in which the thermistor chip, the electrode layer, and a part of the lead wire are sealed with sealing glass is described. In this thermistor element, the thermistor chip is sealed with glass to suppress variation in resistance value.
Patent Document 2 describes an axial lead glass sealed thermistor in which a chip thermistor element is inserted into a glass tube, and sealing electrodes are sealed at both ends of the glass tube.

JP-A-8-78208 JP-A-11-283811

The following problems remain in the conventional technology.
That is, when the conventional temperature sensor is mounted on the surface of the substrate, as shown in FIG. 3A, when connected to the temperature detection circuit, self-heating occurs due to the current I flowing through the thermistor element 101, and the heat generation. The amount is affected by the humidity around the thermistor element 101, so that there is a problem that the detected temperature varies depending on the humidity. For example, in the thermistor element described in Patent Document 1, the thermistor chip is sealed with glass, but the amount of heat generated by the thermistor chip is affected by the surrounding air and humidity through the glass, so that accurate temperature detection is possible. It was difficult. In FIG. 3, the symbol R is a resistance.
Further, in the thermistor described in Patent Document 2, since there is a space between the thermistor element and the glass tube, it is relatively less affected by the outside air, but the contact area between the sealing electrode and the inner surface of the glass tube is large. There was an inconvenience that heat was transmitted from the contact portion and was affected by the outside air and humidity.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a temperature sensor that is not easily affected by ambient humidity and can detect a temperature of a mounting target such as a substrate with high accuracy.

  The present invention employs the following configuration in order to solve the above problems. That is, the temperature sensor according to the first aspect of the present invention includes a thermistor member, a pair of terminal electrode members that are opposed to both ends of the thermistor member and in contact with the both ends, and the pair of terminal electrode members disposed at both ends. And an insulating tube that seals the thermistor member together with an inert gas or in a vacuum, and the thermistor member is formed of a thermistor material at both ends of the thermistor body. A convex electrode having a pair of terminal portions to be formed electrodes, the terminal electrode member projecting inward through a gap between the insulating tube and contacting the terminal portion It has the part on the central axis.

In this temperature sensor, the terminal electrode member has a convex electrode portion on the central axis that protrudes inward through a gap between the insulating tube and the terminal portion. An annular space is also formed between the insulating tube and the heat insulating property between the insulating tube and the insulating tube is improved by the space, and the thermal conductivity from the insulating tube can be reduced. As a result, the influence of outside air and humidity received by the insulating tube can be reduced, and the thermistor element body can receive mainly the heat transferred from the substrate or the like to be mounted to the terminal electrode member in the mounted state. It becomes possible to measure the temperature of this with high accuracy.
Since the thermistor member is sealed in the insulating tube together with an inert gas or in a vacuum, the thermistor body is not exposed to moisture from the outside due to the insulating tube and the inert gas or vacuum. The amount of heat generated when connected to the temperature detection circuit can be made constant regardless of the humidity. In particular, since an inert gas or vacuum with high heat insulation is interposed around the thermistor body, the influence of ambient air and humidity via the inert gas or vacuum can be reduced as much as possible. Therefore, since the phenomenon in which an error has occurred according to humidity is eliminated, temperature detection can be performed with high accuracy. Moreover, since the chip-like thermistor member having the terminal portions at both ends is housed in the insulating tube having the terminal electrode members at both ends, the whole is compact and the surface mounting on the substrate is easy. Become. Note that responsiveness is improved by downsizing.

A temperature sensor according to a second invention is the temperature sensor according to the first invention, wherein the terminal electrode member has a flange portion that is provided on a proximal end side of the convex electrode portion and has an outer diameter larger than an inner diameter of the insulating tube. The flange portion is bonded to an end surface of the insulating tube and exposed to the outside.
That is, in this temperature sensor, since the flange portion is bonded to the end face of the insulating tube and exposed to the outside, the flange portion can be directly bonded and mounted on the substrate or the like which is the mounting target by soldering or the like. In addition, surface mounting is facilitated and heat can be efficiently received from the substrate or the like through the flange portion.

A temperature sensor according to a third invention is characterized in that, in the first or second invention, the convex electrode portion has a concave portion into which the terminal portion can be fitted at a tip.
That is, in this temperature sensor, since the convex electrode portion has a concave portion at which the terminal portion can be fitted at the tip, both end portions of the thermistor body are fitted in the concave portions of the pair of convex electrode portions. The element body is positioned. Thereby, the thermistor body can be installed with high accuracy on the central axis in the insulating tube.

The temperature sensor according to a fourth aspect of the present invention is the temperature sensor according to any one of the first to third aspects, wherein the convex electrode portion is provided at a column portion protruding toward the terminal portion and at a tip end of the column portion. And a support plate portion that contacts the terminal portion, wherein the column portion has an outer diameter smaller than that of the terminal portion.
That is, in this temperature sensor, since the column portion has an outer diameter smaller than that of the terminal portion, a wide annular space can be obtained between the column portion and the insulating tube, and the column structure includes a column structure. The release of Joule heat becomes smaller with respect to the inflow of heat from the terminal, and the influence of the outside air at the terminal portion can be suppressed.

A temperature sensor according to a fifth aspect of the present invention is the temperature sensor according to any one of the first to fourth aspects, wherein an exposed surface of the thermistor body is coated with a glass film.
That is, in this temperature sensor, the exposed surface of the thermistor element is coated with a glass film, so that the thermistor element is not affected by high heat and inert gas during sealing, and a good sealing state can be obtained. .

A temperature sensor according to a sixth invention is characterized in that, in the fifth invention, the insulating tube is made of ceramics, and the terminal electrode member and the insulating tube are brazed.
That is, in this temperature sensor, since the insulating tube is formed of ceramics and the terminal electrode member and the insulating tube are brazed, the glass-coated thermistor body is affected by high heat during brazing. It is difficult, and high reliability can be obtained by a high-strength insulating tube and a high bonding strength sealing state.

A temperature sensor according to a seventh invention is the temperature sensor according to any one of the first to sixth inventions, wherein the thermistor element body is a ceramic sintered body having a crystal structure having a cubic spinel phase as a main phase. Features.
That is, in this temperature sensor, since the thermistor body is a ceramic sintered body having a crystal structure having a cubic spinel phase as a main phase, there is no anisotropy and there is no impurity layer. The variation in electrical characteristics in the body is small, and high-precision measurement is possible when using a plurality of temperature sensors. In addition, since it has a stable crystal structure, it is highly reliable against the environment. As the ceramic sintered body, a single-phase crystal structure composed of a cubic spinel phase is most desirable.

The present invention has the following effects.
That is, according to the temperature sensor of the present invention, the terminal electrode member has a convex electrode portion on the central axis that protrudes inward through a gap between the terminal electrode member and the insulating tube on the central axis. Therefore, it is possible to reduce the influence of the outside air and humidity received by the insulating tube, and it is possible to measure the temperature of the substrate or the like that is the mounting target with high accuracy.
Therefore, it is possible to measure the temperature of a substrate that is a mounting target with high accuracy, and it can be easily surface-mounted as an SMD type temperature sensor, and can be automatically mounted on a glass epoxy substrate, and has high mass productivity. be able to.

In 1st Embodiment of the temperature sensor which concerns on this invention, it is a perspective view which shows a temperature sensor. In 1st Embodiment, it is a disassembled perspective view which shows a temperature sensor. It is an equivalent circuit diagram at the time of connecting the temperature sensor (a) of a prior art example, and the temperature sensor (b) of 1st Embodiment to a temperature detection circuit. In 2nd Embodiment of the temperature sensor which concerns on this invention, it is a perspective view which shows a thermistor member and a terminal electrode member. In 3rd Embodiment of the temperature sensor which concerns on this invention, it is a perspective view which shows a thermistor member and a terminal electrode member. In 4th Embodiment of the temperature sensor which concerns on this invention, it is a perspective view which shows a thermistor member and a terminal electrode member. It is explanatory drawing which shows the relationship between the inflow of the heat from the outside, and the discharge | release of a Joule heat in the case of 1st Embodiment and 4th Embodiment.

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

  As shown in FIGS. 1 and 2, the temperature sensor 1 of the present embodiment includes a thermistor member 2, a pair of terminal electrode members 3 that are disposed opposite to both ends of the thermistor member 2 and are in contact with the both ends, A pair of terminal electrode members 3 are provided at both ends, and an insulating tube 4 is provided for sealing the thermistor member 2 together with an inert gas.

The thermistor member 2 has a chip shape having a thermistor element body 5 made of a thermistor material and a pair of terminal portions 6 serving as electrodes formed at both ends of the thermistor element body 5. That is, the thermistor member 2 is a chip thermistor.
Examples of the thermistor body 5 include thermistor materials such as NTC type, PTC type, and CTR type. In this embodiment, for example, an NTC type thermistor is used. This thermistor material is formed of a thermistor material such as a Mn—Co—Cu-based material or a Mn—Co—Fe-based material.

  In particular, in the present embodiment, as the thermistor element body 5, a ceramic sintered body containing metal oxides of Mn, Co, and Fe, that is, one formed of a Mn—Co—Fe-based material is employed. Furthermore, this ceramic sintered body preferably has a crystal structure having a cubic spinel phase as a main phase. In particular, as a ceramic sintered body, a single-phase crystal structure composed of a cubic spinel phase is most desirable.

The exposed surface of the thermistor body 5 is coated with a glass film 7.
The insulating tube 4 is formed of a ceramic such as alumina (Al ₂ O ₃ ) in a square tube shape, and the terminal electrode member 3 and the insulating tube 4 are brazed.
Examples of the inert gas include He, Ar, Ne, Xe, SF ₆ , CO ₂ , C ₃ F ₈ , C ₂ F ₆ , CF ₄ , H _2, and a mixed gas thereof.

The terminal electrode member 3 is sealed at both ends of the insulating tube 4 by brazing by high-temperature heating, and is sealed so that the central axis of the thermistor member 2 coincides with the central axis of the insulating tube 4.
This terminal electrode member 3 is, for example, Kovar (registered trademark), which is an alloy including nickel (Ni), cobalt (Co), iron (Fe), or 42 alloy including nickel (Ni), iron (Fe). It consists of

The terminal electrode member 3 has a convex electrode portion 3a on the central axis that protrudes inward through a gap between the terminal electrode member 3 and the insulating tube 4, and contacts the terminal portion 6. The flange portion 3b is provided on the proximal end side of the portion 3a and has an outer diameter larger than the inner diameter of the insulating tube 4. That is, the convex electrode portion 3 a is formed to have a smaller diameter than the inner diameter of the insulating tube 4.
The flange portion 3b is joined to the end face of the insulating tube 4 and exposed to the outside. That is, when the temperature sensor 1 of the present embodiment is mounted on a circuit board or the like that is an object to be mounted, the pair of flange portions 3b exposed to the outside from the end portions of the insulating tube 4 are replaced with a conductive adhesive such as solder. Thus, surface mounting can be achieved by bonding to the wiring of the circuit board.

  As described above, in the temperature sensor 1 of the present embodiment, the terminal electrode member 3 has the convex electrode portion 3a that protrudes inward and contacts the terminal portion 6 and has a diameter smaller than the inner diameter of the insulating tube 4 on the central axis. Therefore, an annular space is also formed between the convex electrode portion 3a and the insulating tube 4, and the heat insulation between the insulating tube 4 is improved by the space, and the heat from the insulating tube 4 is improved. Conductivity can be reduced. Thereby, the influence of the external air and humidity which the insulating tube 4 receives can be reduced, and the thermistor element body 5 can mainly receive the heat transferred from the substrate or the like which is the mounting target in the mounted state to the terminal electrode member 3. The temperature of the substrate or the like can be measured with high accuracy.

  Further, since the flange portion 3b is joined to the end face of the insulating tube 4 and exposed to the outside, the flange portion 3b can be directly joined to the substrate or the like, which is a mounting target, with solder or the like, and can be mounted. Mounting becomes easy and heat can be efficiently received from the substrate or the like via the flange portion 3b.

  Since the thermistor member 2 is sealed in the insulating tube 4 together with the inert gas, as shown in FIG. 3B, the thermistor element body 5 is opened to the outside by the insulating tube 4 and the inert gas. Therefore, the amount of heat generated when connected to the temperature detection circuit can be made constant regardless of the ambient humidity. In particular, since an inert gas having high heat insulation is interposed around the thermistor element body 5, the influence of ambient air and humidity via the inert gas can be reduced as much as possible.

  Therefore, since the phenomenon in which an error has occurred according to humidity is eliminated, temperature detection can be performed with high accuracy. In addition, since the chip-like thermistor member 2 having the terminal portions 6 at both ends is housed in the insulating tube 4 having the terminal electrode members 3 at both ends, the whole becomes compact, and is applied to the substrate. Surface mounting becomes easy. Note that responsiveness is improved by downsizing.

Moreover, since the glass film 7 is coated on the exposed surface of the thermistor element body 5, the thermistor element body 5 is not affected by high heat or inert gas during sealing, and a good sealing state is obtained.
Furthermore, since the insulating tube 4 is formed of ceramics and the terminal electrode member 3 and the insulating tube 4 are brazed, the glass-coated thermistor body 5 is not easily affected by high heat during brazing. At the same time, high reliability can be obtained by the high-strength insulating tube 4 and the sealed state of high bonding strength.

  Further, since the thermistor body 5 is a ceramic sintered body having a crystal structure having a cubic spinel phase as a main phase, there is no anisotropy and there is no impurity layer. Variation is small, and highly accurate measurement is possible when using a plurality of temperature sensors 1. In addition, since it has a stable crystal structure, it is highly reliable against the environment.

  Next, second to fourth embodiments of the temperature sensor according to the present invention will be described below with reference to FIGS. In the following description of each embodiment, the same constituent elements described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The difference between the second embodiment and the first embodiment is that the tip surface of the convex electrode portion 3a is flat in the first embodiment, whereas the temperature sensor 21 of the second embodiment is shown in FIG. As shown, the convex electrode portion 23a has a concave portion 23b into which the terminal portion 6 can be fitted at the tip.
That is, in the second embodiment, a concave portion 23b having a rectangular cross section corresponding to the shape of the terminal portion 6 and having a substantially square shape when viewed from the axial direction is formed at the tip of the convex electrode portion 23a. The thermistor body 5 is incorporated in the insulating tube 4 with the terminal portion 6 fitted therein.

  Therefore, in the temperature sensor 21 of the second embodiment, the convex electrode portion 23a has the concave portion 23b into which the terminal portion 6 can be fitted, so that the thermistor is disposed in the concave portion 23b of the pair of convex electrode portions 23a. The thermistor body 5 is positioned by fitting both ends of the body 5. Thereby, the thermistor element body 5 can be installed with high accuracy on the central axis in the insulating tube 4.

  Further, the difference between the third embodiment and the second embodiment is that, in the second embodiment, the concave portion 23b having a rectangular cross section is formed at the tip of the convex electrode portion 23a, whereas the third embodiment is different. In this temperature sensor 31, as shown in FIG. 5, a concave portion 33b having an arcuate cross section is formed at the tip of the convex electrode portion 33a. That is, in the third embodiment, the distal end surface of the convex electrode portion 33a has a concave curved surface shape, and positioning is performed by fitting the terminal portion 6 so as to be sandwiched between the curved surfaces of the concave portion 33b. Thus, also in the temperature sensor 31 of the third embodiment, the thermistor element body 5 can be positioned and supported in the insulating tube 4 as in the second embodiment.

Furthermore, the difference between the fourth embodiment and the first embodiment is that, in the first embodiment, the convex electrode portion 3a has a rectangular parallelepiped shape, whereas in the temperature sensor 41 of the fourth embodiment, FIG. As shown, it has a column part 43c that protrudes from the flange part 3b toward the terminal part 6, and a support plate part 43b that is provided at the tip of the column part 43c and contacts the terminal part 6, and the column part 43c is The outer diameter is smaller than that of the terminal portion 6.
That is, in the fourth embodiment, the column part 43c is provided in the center of the substantially square support plate part 43b, and the convex electrode part 43a has a T-shaped cross section. The support plate portion 43 b has a plane having substantially the same shape as the end surface of the terminal portion 6, and the column portion 43 c is set to have an area where the cross-sectional area orthogonal to the axial direction is smaller than the end surface of the terminal portion 6. .

  Therefore, in the temperature sensor 41 of the fourth embodiment, since the column portion 43c has a smaller outer diameter than the terminal portion 6, a wide annular space can be obtained between the column portion 43c and the insulating tube 4. The column structure by the pillar portion 43c makes it possible to reduce the release of Joule heat with respect to the inflow of heat from the outside, thereby suppressing the influence of the terminal portion from the outside air.

  When measuring the temperature, as shown in FIG. 7A, the inflow of heat from the outside (arrow A in the figure) and the release of Joule heat generated in the thermistor body 5 (arrow B1 in the figure) At equilibrium. At this time, in the first embodiment, the thermistor element body 5 is supported by the convex electrode portion 3a having a larger outer diameter than the terminal portion 6, but the release of Joule heat (arrow B1 in the figure) is relatively large. Thus, the influence of the outside air at the terminal portion 6 is increased. On the other hand, in the fourth embodiment, as shown in FIG. 7B, the release of Joule heat (arrow B2 in the figure) can be made relatively small by the thin column part 43c, and the terminal part 6 The influence with the outside air in can be suppressed.

  The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, the insulating tube is made of ceramics and brazed to the terminal electrode member, but may be joined to the terminal electrode member by welding. Moreover, the insulating tube may be formed of resin, and the insulating tube made of resin and the terminal electrode member may be bonded with an adhesive.
Moreover, in the said embodiment, although the thermistor member is sealed with the inert gas in the insulating tube, you may seal a thermistor member in a vacuum in an insulating tube.

  DESCRIPTION OF SYMBOLS 1 ... Temperature sensor, 2 ... Thermistor member, 3, 23, 33, 43 ... Terminal electrode member, 3a, 23a, 33a, 43a ... Convex electrode part, 3b ... Flange part, 4 ... Insulating tube, 5 ... Thermistor element Body, 6 ... Terminal part, 7 ... Glass film, 23b, 33b ... Recess, 43b ... Support plate part, 43c ... Column part

Claims (7)

A thermistor member;
A pair of terminal electrode members disposed opposite to both end portions of the thermistor member and in contact with the both end portions;
An insulating tube that seals the thermistor member with an inert gas or in a vacuum inside the pair of terminal electrode members,
The thermistor member is a thermistor body formed of a thermistor material;
A chip shape having a pair of terminal portions to be electrodes formed at both ends of the thermistor body;
The temperature sensor characterized in that the terminal electrode member has a convex electrode portion on the central axis that protrudes inwardly through a gap between the terminal electrode member and the insulating tube and contacts the terminal portion. The temperature sensor according to claim 1,
The terminal electrode member has a flange portion provided on a proximal end side of the convex electrode portion and having a larger outer diameter than an inner diameter of the insulating tube;
The temperature sensor, wherein the flange portion is joined to an end face of the insulating tube and exposed to the outside. The temperature sensor according to claim 1 or 2,
The temperature sensor characterized in that the convex electrode part has a concave part into which the terminal part can be fitted. The temperature sensor according to any one of claims 1 to 3,
The convex electrode portion, a column portion protruding toward the terminal portion,
A support plate provided at the tip of the column and abutting against the terminal,
The temperature sensor, wherein the column part has an outer diameter smaller than that of the terminal part. The temperature sensor according to any one of claims 1 to 4,
A temperature sensor, wherein an exposed surface of the thermistor body is coated with a glass film. The temperature sensor according to claim 5,
The insulating tube is formed of ceramics;
The temperature sensor, wherein the terminal electrode member and the insulating tube are brazed. In the temperature sensor as described in any one of Claim 1 to 6,
The temperature sensor, wherein the thermistor body is a ceramic sintered body having a crystal structure having a cubic spinel phase as a main phase.

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