JP5321327B2 - Thermal environment sensor - Google Patents

Description

  The present invention relates to a sensor that detects environmental values such as humidity, wind speed, and atmospheric pressure, and more particularly to a heat dissipation type environmental sensor that detects a predetermined environmental value by using a change in heat dissipation characteristics from the sensor to the environment.

  For example, Patent Documents 1 to 3 are disclosed as sensors using characteristics in which the heat dissipation characteristics from the sensor to the environment depend on the environmental value to be detected. Patent Document 1 is a humidity sensor, Patent Document 2 is a wind speed sensor, and Patent Document 3 is a humidity sensor.

  A configuration example of the humidity sensor of Patent Document 1 will be described with reference to FIG. FIG. 1 is an exploded perspective view of the humidity sensor of Patent Document 1. FIG. In this humidity sensor, a humidity sensor 2 and a temperature compensator 3 are installed in a holder 1, and the humidity sensor 2 and the temperature compensator 3 are covered with a hood 4. And the external wiring 6 is electrically connected to the humidity sensor 2 and the temperature compensator 3 in the cover 5.

JP-A-11-160268 JP-A-6-27127 Japanese Utility Model Publication No. 6-65855

  In the configuration of Patent Document 1, since it is necessary to separately provide a compensation element (temperature compensator) and a detection element (humidity sensor), the entire configuration is large. In addition, when used as a single sensor, a sealing structure using a holder and a hood is necessary, which increases the number of components and increases the manufacturing cost. Further, when the compensation element and the detection element are separated from each other, there is a problem that a difference between the environmental temperatures causes an error.

  In addition, when the compensation element and the sensing element are provided separately, there may be a variation in the characteristics of the compensation element and the sensing element (for example, material variation between the lots in the manufacturing process). The sensitivity and responsiveness of the environmental sensor may be reduced or may vary.

  The configurations of Patent Document 2 and Patent Document 3 also have a problem due to providing a compensation element and a detection element separately.

  Accordingly, an object of the present invention is to reduce an error due to a difference in environmental temperature between the compensation element and the sensing element, to reduce characteristic variation between the compensation element and the sensing element, to eliminate a special sealing structure, and to reduce the overall heat dissipation. It is to provide a type environmental sensor.

In order to solve the above-described problems, the heat radiation type environmental sensor of the present invention is configured as follows.
(1) In an environmental sensor including a temperature-sensitive resistance element for detecting an environmental value and a temperature-sensitive resistance element for temperature compensation for detecting a (predetermined) environmental value on which heat dissipation depends,
At least a ceramic body in which a heat detection part formed on the first main surface side and a temperature compensation part formed on the second main surface side are made of a thermistor material,
A heat detection unit electrode provided in the heat detection unit, for using the thermistor material of the heat detection unit as the temperature-sensitive resistance element for detecting the environmental value;
A temperature compensation unit electrode provided in the temperature compensation unit, for using the thermistor material of the temperature compensation unit as the temperature-sensitive resistance element for temperature compensation;
With
A heat insulating part is provided between the heat detecting part and the temperature compensating part of the ceramic body.

  With this structure, so to speak, the compensation element and the detection element are integrated. By integrating the heat detection unit and the temperature compensation unit, variations between the compensation element and the detection element (for example, material variations between the lots in the manufacturing process and the lots in the manufacturing process) can be reduced. Since it has temperature characteristics, errors due to environmental temperature differences can be minimized.

Further, since the compensation element and the detection element are integrated, the size can be reduced, and it is not necessary to seal the compensation element and the detection element, so that the cost can be reduced.
Further, it can be easily manufactured by the same method as that for a general multilayer ceramic component, and the cost can be reduced.
Further, a heat radiation type environmental sensor that can be surface-mounted can be configured by forming external electrodes on the ceramic body.

(2) The heat insulating part is constituted by a cavity provided in the ceramic body.
Since air has the lowest thermal conductivity among all materials, the heat insulation effect is maximized by forming cavities.

(3) The peripheral part which comprises the periphery of the said cavity part among the said ceramic element bodies may be comprised with the porous member.
With this configuration, the heat insulating action is enhanced by the porous layer disposed around the cavity, and the substantial heat capacity of the heat detection unit is further reduced.

(4) The entirety of the heat insulating part may be composed of a porous member.
With this configuration, the bending strength of the thermistor element is higher than when a cavity is formed.

(5) It is assumed that the ceramic body includes a plurality of ceramic layers, and the heat detection unit electrodes partially overlap with each other through the ceramic layers.
When the heat detection unit electrodes connected to different potentials are arranged so as to overlap each other in the thickness direction with the ceramic layer interposed therebetween, the resistance value between the heat detection unit electrodes can be set low, so that a high SN ratio characteristic. Can be obtained.

(6) The external electrode connected to the heat detection unit electrode and the external electrode connected to the temperature compensation unit electrode are arranged on the outer surface of the ceramic body in a thermally separated state.
With this structure, the heat capacity of the heat detection unit is reduced, and the heat insulation between the heat detection unit and the temperature compensation unit is further improved.

(7) The via electrode connected to the heat detection unit electrode and the via electrode connected to the temperature compensation unit electrode are not connected in the vertical direction of the ceramic body (direction between the heat detection unit and the temperature compensation unit). It shall be arranged in a state.

  With this structure, the heat capacity of the heat detection unit is reduced, and the heat insulation between the heat detection unit and the temperature compensation unit is further improved.

(8) A means for heating or heating the ceramic body is provided. That is, in a state where the temperature of the ceramic body is raised, a predetermined environmental value is detected using a change in heat dissipation characteristics from the heat detection unit to the environment.

  According to the present invention, the error due to the difference in environmental temperature between the compensation element and the sensing element is small, the characteristic variation between the compensation element and the sensing element is small, no special sealing structure is required, and the overall size can be reduced. It can be applied to other electronic devices.

It is a disassembled perspective view of the humidity sensor of patent document 1. FIG. It is sectional drawing of the thermal radiation type environmental sensor 101 which concerns on 1st Embodiment. It is a block diagram (stacking drawing) of each ceramic green sheet at the time of comprising the thermal radiation type environmental sensor 101 which concerns on 1st Embodiment by the laminated structure of a ceramic. FIG. 4 is a cross-sectional view of a ceramic body configured by laminating and firing the ceramic green sheets shown in FIG. 3. FIG. 5 is a perspective view of a state before and after forming an external electrode on the ceramic body shown in FIG. 4. It is sectional drawing in the state which mounted the thermal radiation type environmental sensor 101 shown in FIG. It is an example of the thermal radiation type environmental sensor circuit using the thermal radiation type environmental sensor 101 which concerns on 1st Embodiment. It is a figure which shows the mode of the change of the output voltage of a thermal radiation type | mold environmental sensor circuit by the change of the predetermined | prescribed environmental value which should be detected. It is a block diagram (stacking drawing) of each ceramic green sheet at the time of comprising the thermal radiation type environmental sensor which concerns on 2nd Embodiment by the laminated structure of a ceramic. FIG. 10 is a cross-sectional view of a ceramic body configured by stacking and firing the ceramic green sheets shown in FIG. 9. It is a perspective view of the state before and behind formation of the external electrode with respect to the ceramic body shown in FIG. It is sectional drawing of the radiation type environmental sensor 103 which concerns on 3rd Embodiment. It is sectional drawing of radiation type environmental sensors 104 and 105 concerning a 4th embodiment.

<< First Embodiment >>
FIG. 2 is a cross-sectional view of the heat dissipation-type environmental sensor 101 according to the first embodiment. The heat radiation type environmental sensor 101 includes a ceramic body 30 made of a negative characteristic (NTC) thermistor ceramic that is a heat radiation type environmental sensor body, heat detection unit electrodes 21 and 22, temperature compensation unit electrodes 26 and 27, an external electrode 23, 24 and 28 and a cavity 25 are provided.

  The vicinity of the surface layer portion on the first main surface side of the ceramic body 30 is a heat detection portion, and the heat detection portion electrodes 21 and 22 are formed in the heat detection portion. The vicinity of the surface layer portion on the second main surface side of the ceramic body 30 is a temperature compensation portion for the heat detection portion, and temperature compensation portion electrodes 26 and 27 are formed in the temperature compensation portion.

  The thermistor ceramic part of the heat detection part is used as a temperature sensitive resistance element for detecting an environmental value by the heat detection part electrodes 21 and 22. Similarly, the thermistor ceramic portion of the temperature compensation unit is used as a temperature compensation resistance element for temperature compensation by the temperature compensation unit electrodes 26 and 27.

  The hollow portion 25 is formed as a heat insulating portion that insulates between the heat detecting portion and the temperature compensating portion.

Here, a manufacturing method of the heat radiation type environmental sensor 101 will be described.
FIG. 3 is a configuration diagram (stacking diagram) of each ceramic green sheet when the heat-dissipation-type environment sensor 101 is configured with a ceramic laminated structure. In FIG. 3, the internal electrode paste 21 </ b> P that becomes the heat detection part electrode 21 by the subsequent baking is formed on the layer S <b> 1, and the internal electrode paste 22 </ b> P that becomes the heat detection part electrode 22 by the subsequent baking is formed on the layer S <b> 2. Yes. The layer S7 is formed with an internal electrode paste 26P that becomes the temperature compensation portion electrode 26 by subsequent firing, and the layer S8 is formed with an internal electrode paste 27P that becomes the temperature compensation portion electrode 27 by later firing. Further, an electrode paste 29P for via electrodes is formed on the layer S9. In addition, holes are formed in the layers S4 and S5, and a material 25 that is volatilized by firing in the holes, for example, an organic substance such as a binder or a filler 25P such as a carbon paste is formed.

  FIG. 4 is a cross-sectional view of a ceramic body configured by laminating and firing the ceramic green sheets shown in FIG. Inside the ceramic body, heat detection unit electrodes 21 and 22, temperature compensation unit electrodes 26 and 27, and via electrodes 29 are formed. Moreover, the cavity 25 is formed by volatilizing the filling 25P filled in the layers S4 and S5 by firing.

  FIG. 5 is a perspective view of the ceramic element body shown in FIG. 4 before and after forming external electrodes. 5A is a perspective view of the ceramic body before forming the external electrode, FIG. 5B is a perspective view after forming the external electrode, and FIG. 5C is the state shown in FIG. 5B. It is the perspective view which looked at the opposite surface side.

  The external electrode 23 is electrically connected to the heat detection part electrode 21, and the external electrode 24 is electrically connected to the heat detection part electrode 22 and the temperature compensation part electrode 26. The external electrode 28 is electrically connected to the via electrode 29. The center portion of the temperature compensation electrode 27 is thermally coupled to the external electrode 28 with a low thermal resistance.

  In this way, the via electrode 29 that is electrically connected to the temperature compensation electrode 27 is formed so as to be exposed at the center of the bottom surface of the rectangular parallelepiped ceramic body, and the external electrode 28 that is electrically connected to the via electrode 29 is opposed from the bottom surface. By forming over two side surfaces, the contact area between the temperature compensation unit and the substrate increases, so that the heat of the temperature compensation unit can be effectively radiated to the substrate side. Thereby, the amount of heat radiated from the temperature compensation unit to the air can be reduced.

Thermistor ceramics used in the ceramic body are semiconductor ceramics whose resistance value changes with temperature. For example, a plurality of transition metal oxides such as manganese, nickel, cobalt, iron, copper, aluminum, titanium, and zinc are sintered. An NTC thermistor material may be used, and for example, a BaTiO ₃ -based PTC thermistor material to which a rare earth element is added as a donor may be used.

  Moreover, any material can be selected for the heat detection part electrodes 21 and 22 as long as the material is an electrode material that is in ohmic contact with the thermistor ceramics. For example, if the thermistor ceramic used for the ceramic body is an NTC thermistor material, it is composed of Ag, Pd, Pt or an alloy thereof, and if it is a PTC thermistor material, it is composed of Ni, Cu, Al or an alloy thereof. Composed.

  Since the resistances of the heat detection unit electrodes 21 and 22 can be adjusted by the facing distance and the overlapping area of the ceramic body 30 in plan view, the resistivity (ratio) of the thermistor ceramics is used to obtain a desired resistance value. The pattern and layer position of the heat detection part electrodes 21 and 22 are determined in accordance with the resistance.

  Since this heat-dissipating environment sensor is a multilayer ceramic component, it can be easily manufactured and the cost can be reduced. Furthermore, since surface mounting is possible using the external electrodes 23 and 24, it is possible to reduce the size and cost as compared with conventional sensors packaged using a metal case and sensors incorporated on a substrate. Can be achieved.

  Further, as shown in FIGS. 2 and 3, when the two heat detection unit electrodes 21 and 22 and the temperature compensation unit electrodes 26 and 27 are arranged to face each other so as to overlap in the thickness direction with a ceramic layer interposed therebetween, The resistance value between the heat detection unit electrodes 21 and 22 and the temperature compensation unit electrodes 26 and 27 can be set low, and high SN ratio characteristics can be easily obtained due to the circuit configuration of the heat radiation type environmental sensor circuit described later.

A specific manufacturing method is as follows. Here, an example of a ceramic body made of thermistor ceramics using NTC thermistor material will be described.
First, a predetermined amount of transition metal oxides such as Mn ₃ O ₄ , NiO, Co ₃ O ₄ , Fe ₂ O _{3 and the} like are weighed, and then the weighed material is put into a ball mill containing a grinding medium such as zirconia. And sufficiently wet pulverized, and then calcined at a predetermined temperature to produce a ceramic powder.

  Next, an organic binder is added to the ceramic powder, and a wet mixing process is performed to form a slurry. Thereafter, a molding process is performed using a doctor blade method or the like to produce a ceramic green sheet.

  Next, an internal electrode paste mainly composed of Ag-Pd is used for the ceramic green sheet located in the heat detection part or temperature compensation part of the ceramic green sheet, and screen printing is performed on the ceramic green sheet to form an internal electrode pattern. Form. Also, the ceramic green sheet located in the cavity is filled with a material that volatilizes by drilling the ceramic green sheet by laser processing or the like and firing into the hole, for example, organic matter such as a binder or carbon paste. To form a cavity pattern.

  Next, after laminating the ceramic green sheet on which the internal electrode pattern is screen-printed and the green sheet on which the cavity pattern is processed as shown in FIG. 3, the electrode pattern is sandwiched between the ceramic green sheets on which the screen pattern is not screen-printed, A laminate is produced by pressure bonding. Next, the laminate is cut into a predetermined size, accommodated in a zirconia basket, subjected to a binder removal treatment, and then fired at a predetermined temperature (for example, 1000 ° C. to 1300 ° C.). As a result, organic substances such as a binder, carbon paste, and the like are volatilized, and a cavity is formed near the center of the ceramic body. Thus, the ceramic body 30 including the heat detection unit electrodes 21 and 22, the temperature compensation unit electrodes 26 and 27, the via electrode 29, and the cavity portion 25 is configured.

  Thereafter, external electrode paste containing Ag or the like is applied to both ends of the ceramic body 30 and baked to form external electrodes 23 and 24. The external electrodes 23 and 24 may be formed by a thin film forming method such as a sputtering method or a vacuum evaporation method as long as the adhesion is good.

In the above example, an oxide such as Mn ₃ O ₄ is used as the ceramic raw material, but an Mn carbonate, hydroxide, or the like can also be used.

FIG. 6 is a cross-sectional view in a state where the heat radiation type environmental sensor 101 shown in FIG. 2 is mounted on a mounting board (a circuit board of an electronic device to be assembled).
A heat radiation type environmental sensor 101 is surface-mounted on the land L on the mounting substrate PWB. A fillet of solder S is formed from the land L on the mounting substrate PWB to the external electrodes 23 and 24.

  As will be described later, a constant current is applied to the environmental value detecting temperature sensitive resistance element and the temperature compensating temperature sensitive resistance element. Therefore, the environmental value detecting temperature sensitive resistance element and the temperature compensating temperature sensitive resistance element self-heat by Joule heat. The temperature of the environmental value detecting temperature sensitive resistance element and the temperature compensating temperature sensitive resistance element is stabilized at a temperature at which the heat generation amount and the heat radiation amount to the surroundings are balanced.

  The temperature sensing resistor element for detecting the environmental value, which is a heat detecting portion in which the heat detecting portion electrodes 21 and 22 are formed, has an upper surface and four sides that are open to the external environment. Therefore, the heat capacity of the heat detection unit is smaller than that of a temperature compensation unit, which will be described later, and the heat generation of the environmental value detection temperature sensitive resistance element is mainly radiated to the air. That is, the heat radiation to the air is dominant in the heat radiation of the temperature sensing element for detecting the environmental value.

  On the other hand, the temperature-compensating resistance element, which is a temperature compensation part in which the temperature compensation part electrodes 26 and 27 are formed, is in contact with the mounting substrate PWB and connected by solder S. Further, the temperature compensation portion electrode 27 is electrically connected to the external electrode 28 through the via electrode 29 at the center, and is thermally coupled to the external electrode 28 with a low thermal resistance. Therefore, the heat capacity of the temperature compensation unit is larger than the heat capacity of the heat detection unit, and the temperature-compensating temperature sensitive resistance element is radiated mainly to the mounting substrate PWB side. In other words, the heat radiation of the temperature compensating temperature-sensitive resistor element is predominantly the heat radiation to the mounting substrate PWB.

  The amount of heat released when the heat generated by the temperature sensing resistor for detecting environmental values is radiated into the air varies mainly depending on the environmental values of wind speed, humidity, and atmospheric pressure. For example, focusing on the wind speed, assuming that the humidity and the atmospheric pressure are constant, the amount of heat release changes according to the change in the wind speed. For example, assuming that the wind speed and the atmospheric pressure are constant, the heat radiation amount changes according to the change in humidity. Therefore, if a factor that affects the heat radiation amount other than the predetermined environmental value to be detected is measured by another method, the predetermined environmental value can be detected.

  FIGS. 7A and 7B are two examples of a heat radiation type environmental sensor circuit using the heat radiation type environmental sensor 101. In FIGS. 7A and 7B, the resistance Rs is the resistance of the thermistor of the heat detection unit, and the resistance Rn is the resistance of the thermistor of the temperature compensation unit. The resistors Rs and Rn and the resistors Ro and Ro constitute a resistor bridge circuit. A constant current circuit (constant current source) CCS supplies a constant current to the resistance bridge circuit. The amplifier circuit AMP differentially amplifies the output voltage of the resistance bridge circuit.

  As in the heat dissipation type environmental sensor circuit shown in FIG. 7A, one of two current paths through which a constant current flows is connected to a resistance (temperature-sensitive resistance element for detecting an environmental value) Rs by a thermistor of the heat detection unit and temperature compensation. A high S / N ratio can be obtained by configuring a series circuit with the resistance (temperature-sensitive resistance element for temperature compensation) Rn of the other thermistor and configuring the other with a series circuit of two resistors Ro.

  That is, in the circuit configuration shown in FIG. 7B, a large differential voltage is required unless the resistance value of the resistor Ro is approximately equal to the resistance value Rs of the thermistor of the heat detection unit and the resistance value Rn of the thermistor of the temperature compensation unit. However, in the circuit configuration shown in FIG. 7A, the resistance value of the resistor Ro does not need to be a value that approximates the resistance values of Rs and Rn, so that the degree of freedom in circuit configuration is high. A circuit with a high SN ratio can be configured. For example, the resistance value of the resistor Ro can be made sufficiently small to reduce the input impedance to the amplifier circuit AMP.

According to the heat dissipation type environmental sensor circuit shown in FIGS. 7A and 7B, when the temperature rises due to self-heating of the temperature compensation unit and the heat detection unit, the output voltage varies depending on the mounting situation. Equilibrates to a predetermined value. Here, since the thermistor (temperature compensation thermistor) Rn of the temperature compensation unit compensates for the influence due to the ambient temperature change, the output voltage Vout of the amplifier circuit AMP is a discharge depending on the environment of the thermistor Rs of the heat detection unit. The value depends on the amount of heat. For this reason, when a change occurs in the environment, the output voltage fluctuates due to fluctuations in the temperature of the heat detector. Therefore, the change in the output voltage Vout that changes in response to the environmental change from the balanced output voltage Vout can be used as the environmental value detection signal.
As described above, the environmental value can be detected by measuring the resistance change due to the difference in the heat radiation amount through the heat detection unit electrodes 21 and 22 and the external electrodes 23 and 24.

FIG. 8 is a diagram illustrating a change in the output voltage of the heat dissipation type environmental sensor circuit due to a change in a predetermined environmental value to be detected.
8A is a waveform diagram of a current flowing through the resistance bridge circuit, FIG. 8B is a waveform diagram of temperature changes in the heat detection unit and the temperature compensation unit, and FIG. 8C is a heat detection unit and a temperature compensation. FIG. 8D is a waveform diagram of an output voltage of the heat radiation type environmental sensor circuit.

  As shown in FIG. 8A, when energization is started at time t0, a constant current flows quickly. As shown in FIG. 8B, due to the energization, the temperature Ts of the heat detection unit and the temperature Tn of the temperature compensation unit increase, and a thermal equilibrium state is reached at a predetermined temperature.

  When the environmental value (for example, humidity) to be detected changes at time t1 (in this example, the environmental value changes rapidly at t1), thereafter, the temperature Ts of the heat detection unit and the temperature Tn of the temperature compensation unit are It will be in thermal equilibrium at the new temperature. Thereafter, when the environmental value to be detected changes again at time t2, the temperature Ts of the heat detection unit and the temperature Tn of the temperature compensation unit are thermally balanced again at the new temperature thereafter.

  When energization is stopped at time t3, the temperature Ts of the heat detector and the temperature Tn of the temperature compensator are reduced by the heat radiation of the heat detector.

As shown in FIG. 8C, the resistance value Rs of the thermistor of the heat detection unit and the resistance value Rn of the thermistor of the temperature compensation unit are determined according to the temperatures Ts and Tn.
As shown in FIG. 8D, the output voltage of the heat dissipation type environmental sensor circuit is displaced according to the change in the resistance value of the thermistor of the heat detection unit and the temperature compensation unit after the start of energization to. The output voltage is also stabilized in accordance with the thermal balance between the heat detection unit and the temperature compensation unit. When the environmental value changes at time t1, the output voltage corresponds to the resistance value Rs of the thermistor of the heat detection unit and the resistance value Rn of the thermistor of the temperature compensation unit. When the environmental value changes again at time t2, the output voltage changes again according to the resistance value Rs of the thermistor of the heat detection unit and the resistance value Rn of the thermistor of the temperature compensation unit.

  When the energization is stopped at time t3, the output voltage fluctuates relatively greatly according to changes in the resistance value Rs of the thermistor of the heat detection unit and the resistance value Rn of the thermistor of the temperature compensation unit.

  The output voltage of the heat dissipation type environmental sensor circuit becomes stable when the thermal equilibrium state is reached, such as before the time t1, before the time t2, or before the time t3. Among the stable equilibrium states, the difference between the initial output voltage value in which the environment has not changed and the output voltage in the equilibrium state after the environment change is unique from the environment value to be detected. Since there is a relationship, the environmental value can be obtained by reading the fluctuation of the output voltage of the heat radiation type environmental sensor circuit.

  In addition, after the start of energization to the resistance bridge circuit of the heat dissipation type environmental sensor circuit or after the stop of energization, the output voltage of the heat dissipation type environmental sensor circuit shows a transient voltage change, but the heat detection unit into the air If the heat radiation amount is constant, the output voltage change (transition) is constant. In other words, if the pattern of change (transition) of the output voltage changes, it is caused by a change in environmental value. Therefore, the environmental value can also be detected by the output voltage change pattern and the inclination after time t0 and after time t3.

  In addition, since the thermistor material is used for the ceramic body in the present invention, self-heating is caused by applying current, and the ceramic body can be easily brought into a heating state. For example, a heat radiation type environmental sensor is mounted. A means for heating the substrate may be provided, and the ceramic body may be heated by heating the substrate.

<< Second Embodiment >>
FIG. 9 is a configuration diagram (stacking diagram) of each ceramic green sheet when the heat-dissipating environment sensor according to the second embodiment is configured with a ceramic laminated structure. In FIG. 9, internal electrode paste 21 </ b> P that becomes heat detection portion electrode 21 by later firing is formed on layer S <b> 1, and internal electrode paste 22 </ b> P that becomes heat detection portion electrode 22 becomes later on layer S <b> 2. Yes. The layer S7 is formed with an internal electrode paste 26P that becomes the temperature compensation portion electrode 26 by subsequent firing, and the layer S8 is formed with an internal electrode paste 27P that becomes the temperature compensation portion electrode 27 by later firing. In addition, holes are formed in the layers S4 and S5, and a material 25 that is volatilized by firing in the holes, for example, an organic substance such as a binder or a filler 25P such as a carbon paste is formed.

  FIG. 10 is a cross-sectional view of a ceramic body configured by laminating and firing the ceramic green sheets shown in FIG. Heat detection part electrodes 21 and 22 and temperature compensation part electrodes 26 and 27 are formed inside the ceramic body. Moreover, the cavity 25 is formed by volatilizing the filling 25P filled in the layers S4 and S5 by firing.

  11 is a perspective view of the ceramic body shown in FIG. 10 before and after the formation of the external electrodes. That is, FIG. 11A is a perspective view of the ceramic body before forming the external electrode, and FIG. 11B is a perspective view of the heat radiation type environmental sensor 102 after forming the external electrode.

  The external electrode 23 is electrically connected to the heat detection part electrode 21, and the external electrode 24 is electrically connected to the heat detection part electrode 21 and the temperature compensation part electrode 26. The external electrode 28 is electrically connected to the temperature compensation unit electrode 27.

  As described above, the temperature compensating portion electrode 27 formed by firing the internal electrode paste 27P is formed so as to be exposed on the two side surfaces of the rectangular parallelepiped ceramic body. The probability that the orientations are aligned will increase, and manufacturing efficiency will increase.

  Note that the internal electrode paste 27P does not necessarily have to be drawn out on both sides of the ceramic body in the layer S8, and may have a structure drawn out on one side. In FIG. 11B, the external electrode 28 is formed on one side surface, but since the internal electrode paste 27P is drawn out on both side surfaces of the layer S8, the external electrode 28 is formed on both side surfaces. May be.

<< Third Embodiment >>
FIG. 12 is a cross-sectional view of the radiation environment sensor 103 according to the third embodiment. The radiation environment sensor 103 includes an NTC thermistor ceramic body 30, heat detection electrodes 21 and 22, external electrodes 23 and 24, a cavity 25, and a porous portion 31.

  The porous portion 31 is a peripheral portion of the thermistor ceramic body that forms the periphery of the cavity 25 and is made porous by firing. That is, the ceramic green sheet provided with the opening for forming the cavity 25 is obtained by dispersing in advance organic substances that disappear during firing.

  For example, in the structure shown in FIG. 2 in the first embodiment, the heat insulation effect increases as the width of the cavity 25 is increased, but a peripheral edge that supports the periphery of the cavity 25 is left in order to secure the cavity 25. It is necessary to keep. Therefore, as shown in FIG. 12, by making the peripheral edge supporting the periphery of the cavity 25 porous, the lower part than the heat detection part electrode 22 is more effectively not only by the cavity 25 but also by the porous part 31. Insulated. Therefore, the heat capacity of the heat detector can be further reduced.

<< Fourth Embodiment >>
13A and 13B are sectional views of the radiation environment sensors 104 and 105 according to the fourth embodiment. The radiation environment sensor 104 includes an NTC thermistor ceramic body 30, heat detection electrodes 21, 22, external electrodes 33, 34, 35, 28 and a cavity 25. In FIG. 13B, a porous portion 31 is provided around the cavity portion 25.

In this example, the external electrodes 33 and 34 connected to the heat detection unit electrodes 21 and 22 and the external electrodes 35 and 28 connected to the temperature compensation unit electrodes 26 and 27 are arranged separately from each other both electrically and thermally. Has been. That is, no external electrode is formed on the side surface of the ceramic body. The via electrode is arranged in a non-connected state (non-penetrating state) in the vertical direction of the ceramic body.
Therefore, the heat detection unit and the temperature compensation unit can be further insulated, and the heat capacity of the heat detection unit can be further reduced.

  In each of the embodiments described above, the thermistor material, which is a thermistor material, is laminated and sintered to form a ceramic body, but at least the first main surface side on which the heat detection unit electrode is provided; The second main surface side on which the temperature compensation portion electrode is provided may be formed of a thermistor ceramic layer, and the other layers may be formed of layers of different materials and integrally sintered.

  Moreover, in each embodiment shown above, you may comprise the area | region equivalent to the cavity part 25, or the whole layer which formed the cavity part 25 with a porous member.

  Moreover, in each embodiment shown above, although the single cavity part 25 was provided, you may arrange | position two or more by the up-down direction or a horizontal direction. The shape of the hollow portion may constitute a closed space in the ceramic body, or may be opened at a part or at a plurality of locations. Furthermore, a honeycomb structure or a cell structure may be used. With these configurations, the thermal resistance can be adjusted.

AMP ... amplifier circuit L ... land PWB ... mounting substrate S ... solders S1 to S9 ... layers 21, 22 ... heat detection part electrodes 23, 24 ... external electrode 25 ... cavities 26, 27 ... temperature compensation part electrode 28 ... external electrode 29 ... via electrode 30 ... ceramic body 31 ... porous portions 33, 34, 35 ... external electrodes 101-105 ... radiation-type environmental sensor

Claims (8)

In an environmental sensor equipped with a temperature-sensitive resistance element for detecting an environmental value and a temperature-sensitive resistance element for temperature compensation for detecting an environmental value on which heat dissipation depends,
At least a ceramic body in which a heat detection part formed on the first main surface side and a temperature compensation part formed on the second main surface side are made of a thermistor material,
A heat detection unit electrode provided in the heat detection unit, for using the thermistor material of the heat detection unit as the temperature-sensitive resistance element for detecting the environmental value;
A temperature compensation unit electrode provided in the temperature compensation unit, for using the thermistor material of the temperature compensation unit as the temperature-sensitive resistance element for temperature compensation;
With
A heat dissipation type environmental sensor in which a heat insulating part is provided between the heat detecting part and the temperature compensating part of the ceramic body.   The heat-dissipating environment sensor according to claim 1, wherein the heat insulating portion is a cavity provided in the ceramic body.   The heat-dissipating environmental sensor according to claim 2, wherein a peripheral part of the ceramic body that forms a peripheral part of the heat insulating part is a porous member.   The heat-dissipating environment sensor according to claim 1, wherein the heat insulating portion is formed of a porous member.   5. The heat dissipation type environmental sensor according to claim 1, wherein the ceramic body includes a plurality of ceramic layers, and the heat detection unit electrodes partially overlap with each other through the ceramic layers.   The external electrode connected to the heat detection unit electrode and the external electrode connected to the temperature compensation unit electrode are disposed on the outer surface of the ceramic body in a thermally separated state. A heat dissipation type environmental sensor as described in any of them.   The via electrode conducting to the heat detection unit electrode and the via electrode conducting to the temperature compensation unit electrode are arranged in a non-connected state in the vertical direction of the ceramic body. Heat radiation type environmental sensor.   The heat dissipation-type environmental sensor according to any one of claims 1 to 7, further comprising means for generating heat or heating the ceramic body.

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