JP2009168649A - Indirect heat type heat-sensitive resistance element, and absolute humidity sensor using the indirect heat type heat-sensitivie resistance element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an indirect heat type heat-sensitive resistance element uniformized in shape and characteristic, and an accurate absolute humidity sensor with high response speed and superior mechanical strength, using the indirect heat type heat-sensitive resistance element. <P>SOLUTION: The indirect heat type heat-sensitive resistance element comprises: a substrate; an insulating film 2 formed on the substrate; a heat-sensitive resistance film 5 formed on the insulating film; a heating resistance film 6 formed on the insulating film to surround the circumference of the heat-sensitive resistance film; and electrode pads 3c and 3d, formed on the substrate to electrically connect the heat-sensitive resistance film and the heating resistance film respectively to the outside. The absolute humidity sensor comprises a case. having two recessed part formed symmetrically and a through-hole formed in one of the recessed parts; the indirect heat type heat-sensitive resistance element. disposed in each of the recessed parts of the case; and a lid part closing the indirect heat-sensitive resistance element with the case. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an absolute humidity sensor used for measuring absolute humidity in cooking utensils such as a microwave oven, air conditioning equipment, and various industrial equipment.

  In a microwave oven, the heating finish of a food is detected by measuring a change in humidity in the heating chamber based on water vapor generated from the food by microwave heating. For example, as one of finish detection sensors used for such purposes, there is an absolute humidity sensor disclosed in Japanese Patent Laid-Open No. 9-325126. As shown in FIG. 11, this sensor has a soaking case in which two concave portions 1B and 1C are formed symmetrically in a casing having a flat upper surface, and an opening 1D penetrating the upper surface is provided in one concave portion 1B. The cover 1J is integrated with 1A by joining the flanges, and two self-heating type temperature sensing elements 1E and 1F are provided at the tips of two terminals 1Q provided through the substrate 1P. The temperature sensing element 1E is sealed in a recess 1B having an opening through a substrate to form a moisture sensing element, and the other temperature sensing element 1F is mounted on the other recess 1C. The temperature compensation element is formed by sealing with a gap. It has been disclosed that thermistors having resistances selected in advance and having uniform characteristics are used for the temperature sensitive elements 1E and 1F constituting the absolute humidity sensor (Japanese Patent Laid-Open No. 9-325126, page 5 [0041]). This absolute humidity sensor causes the temperature sensing element 1E and the temperature sensing element 1F to self-heat, and the temperature sensing element 1E detects a change in heat conduction according to the amount of water vapor, while the temperature sensing element 1F is sealed. Compensating for heat conduction in the space, the difference in voltage change between the two temperature sensing elements is converted to absolute humidity.

On the other hand, there is an indirectly heated absolute humidity sensor shown in FIG. In this indirectly heated absolute humidity sensor, a thermistor film 72a is formed on a substrate 71a, a platinum resistance thermometer film 73a is formed around the thermistor film 72a, and a metal frame 75a, the thermistor film 72a, and platinum are formed by a wire 74a. A thermistor film 72b is formed on the substrate 71b and the thermistor film 72b is sealed around the thermistor film 72b in a state of being electrically connected to the resistance temperature detector film 73a and being caught in a hollow state. The body film 73b is formed, and the metal frame 75b, the thermistor film 72b, and the platinum resistance thermometer film 73b are electrically connected by the wire 74b, and the glass tube 76b in which the opening 77b is formed in a hollow state. It consists of a sealed one. The indirectly heated absolute humidity sensor examined by the present applicant is a platinum resistance temperature sensor in the glass tube 76b in which the opening 77b is formed by self-heating the platinum resistance temperature detector films 73a and 73b together. The thermistor film 72b heated by heat conduction from the body film 73b detects a change in heat conduction according to the amount of water vapor, and is heated by heat conduction of the platinum resistance thermometer film 73a in the other sealed glass tube 76a. The thermistor film 72a thus compensated for heat conduction in the space converts the difference in voltage change between the two thermistor films 72a and 72b into absolute humidity.
JP-A-9-325126

  However, the absolute humidity sensor disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 9-325126 needs to prepare the temperature sensitive elements 1E and 1F that have been subjected to resistance selection in advance and have the same characteristics, which requires man-hours. Further, even in the temperature-sensitive elements 1E and 1F subjected to resistance selection, the heat dissipation constant varies due to the variation in shape (volume, surface area), and there is a problem that the detection accuracy of the completed absolute humidity sensor varies. Further, as can be seen from FIG. 11, the temperature sensitive elements 1E and 1F are connected between the tips of the two terminals 1Q and are supported in the hollow, so that there is a problem of difficulty in electrical connection and mechanical strength due to vibration from the outside. It becomes.

  Further, the indirectly heated absolute humidity sensor of FIG. 12 examined by the present applicant also has a problem of difficulty in electrical connection and mechanical strength due to vibration from the outside because the temperature sensitive element is supported in a hollow state.

  The present invention has been made in view of the above problems, and an object thereof is to provide an indirectly heated thermosensitive resistance element having a uniform shape and uniform characteristics. It is another object of the present invention to provide an absolute humidity sensor that uses the indirectly heated temperature sensitive resistance element, has a high response speed, high accuracy, and excellent mechanical strength.

  According to a first aspect of the present invention, there is provided a substrate, an insulating film formed on the substrate, a temperature sensitive resistance film formed on the insulating film, and the insulation surrounding the temperature sensitive resistance film. A heating resistive film formed on the film; and an electrode pad formed on the substrate for electrically deriving the temperature-sensitive resistive film and the heating resistive film to the outside. It is an indirectly heated type temperature sensitive resistance element.

  According to a second aspect of the present invention, there is provided a substrate in which a cavity is formed, an insulating film covering the cavity, a temperature-sensitive resistance film formed on the insulating film, and a periphery of the temperature-sensitive resistance film A heating resistance film formed on the insulating film surrounding the insulating film, and the temperature-sensitive resistance film and the heating resistance film are formed on the insulating film or the substrate in order to electrically lead out each of them to the outside. This is an indirectly heated temperature-sensitive resistance element composed of the formed electrode pad.

  The invention according to claim 3 of the present invention is the indirectly heated temperature-sensitive resistor element according to claim 1 or 2, wherein the temperature-sensitive resistor film is formed of a thin film thermistor.

  The invention according to claim 4 of the present invention is the indirectly heated thermosensitive resistor element according to claim 1, wherein the heating resistive film is formed of a thin film thermistor or a platinum resistance temperature detector.

  The invention according to claim 5 of the present invention is the indirectly heated thermosensitive resistor element according to claim 1 or 2, wherein a base electrode layer is formed between the substrate and the electrode pad.

  The invention according to claim 6 of the present invention is the indirectly heated type according to claim 1, wherein a comb-like electrode is formed between the insulating film, the temperature-sensitive resistance film, and the heating resistance film. It is a temperature sensitive resistance element.

  According to a seventh aspect of the present invention, an insulating protective film is formed on the temperature-sensitive resistance film and the heating resistive film, and a glass protective film is formed on the insulating protective film. The side-heat-type temperature-sensitive resistance element described in 1.

  According to an eighth aspect of the present invention, in the absolute humidity sensor configured using the indirectly heated temperature-sensitive resistance element according to any one of the first to seventh aspects, two concave portions are formed symmetrically, and one concave portion is formed. A case in which a through-hole is formed, the indirectly heated thermosensitive resistor element disposed in each of the recesses of the case, and a lid that closes the indirectly heated thermosensitive resistor element with the case; It is an absolute humidity sensor.

  The invention according to claim 9 of the present invention is an absolute humidity sensor configured using the indirectly heated temperature-sensitive resistance element according to any one of claims 1 to 7, and a case in which two concave portions are formed symmetrically; It is an absolute humidity sensor comprised from the said indirectly heated type thermosensitive resistance element arrange | positioned at each of the recessed part of a case, and the cover part which seals one recessed part.

  According to a tenth aspect of the present invention, there is provided an absolute humidity sensor configured using the indirectly heated temperature-sensitive resistance element according to any one of the first to seventh aspects, wherein the metal CAN in which a through hole is formed and the sealed metal. It is an absolute humidity sensor composed of a case in which CAN is thermally coupled and the indirectly heated thermosensitive resistance element disposed inside each of the two metals CAN.

  The indirectly heated thermosensitive resistor element of the present invention makes the heat distribution uniform by surrounding the periphery of the thermosensitive resistor film on the same plane on the substrate, thereby improving the response speed. It can be made.

  The indirectly heated thermosensitive resistor element of the present invention simultaneously forms a large number of thin film thermistors on the substrate by sputtering, so that it is possible to reduce variations in the resistance values of the mutual thin film thermistors, reducing the number of pairing steps, Cost can be reduced.

  In the indirectly heated thermosensitive resistor element of the present invention, since the shape of the mutual thermosensitive resistor element is uniform, the heat dissipation constant can be made uniform, and the detection accuracy is improved.

  In the indirectly heated thermosensitive resistor element of the present invention, by using the same thin film thermistor as the thermosensitive resistor film for the heating resistive film, the number of materials is reduced, and the man-hour can be reduced.

  The indirectly heated thermosensitive resistor element of the present invention can reduce the heat capacity and improve the detection sensitivity by forming a thin back surface of the substrate on which the temperature sensitive resistance film and the heating resistance film are formed.

  In the indirectly heated thermosensitive resistor element of the present invention, resistance adjustment can be easily performed by forming a comb-like electrode between the insulating film, the thermosensitive resistor film, and the heating resistive film.

  The absolute humidity sensor of the present invention can improve the mechanical strength because the detection part is formed on the substrate without disposing the temperature-sensitive element in the case in a hollow state.

  Hereinafter, a first embodiment of an indirectly heated thermosensitive resistance element according to the present invention will be described with reference to FIGS. FIG. 1 is a top view showing an appearance of a first embodiment of an indirectly heated thermosensitive resistor element of the present invention. 2-6 is a figure which shows one Embodiment of the thin film formation process of the indirectly heated type thermosensitive resistance element shown in FIG. In FIG. 2, the substrate 1 is made of an alumina substrate that is 1.0 mm square and has a thickness of about 50 to 300 μm. Next, an insulating coating layer made of silicon dioxide (SiO 2), silicon nitride (Si 3 N 4) or the like is formed on one surface of the substrate 1 to a thickness of 0.1 to 0.5 μm by sputtering, plasma CVD, or the like. Be filmed. Then, patterning is performed using a photoetching method, and an insulating film 2 is formed on the substrate 1. The insulating film 2 is necessary for preventing a chemical reaction between the temperature-sensitive resistance film, which will be described later, and the heating resistance film and the substrate 1 at the time of heat treatment, and obtaining stable electrical characteristics as an indirectly heated temperature-sensitive resistance element. Is.

  Next, as shown in FIG. 3, the process proceeds to a step of forming a metal base film for forming an electrode pad for leading out to the outside. A metal thin film layer made of at least one of titanium (Ti), chromium (Cr), nickel (Ni), tungsten (W), tantalum (Ta), and Ni—Cr alloy is formed on the substrate 1 by a method such as sputtering or vapor deposition. It is formed. Subsequently, unnecessary portions of the stacked metal thin film layers are removed by a photoetching method to form metal base films 3a and 3b.

  Subsequently, as shown in FIG. 4, a wiring pattern for electrically connecting to the electrode pads 3a and 3b and the thin film thermistor to be a temperature sensitive resistance film on the insulating film 2 and the thin film thermistor to be a heating resistance film. The process proceeds to the step of forming. First, a metal thin film layer made of at least one of platinum (Pt), gold (Au), palladium (Pd), or a palladium alloy is formed on the insulating film 2 and the metal base films 3a and 3b. After the metal thin film layer is formed, unnecessary portions of the metal thin film layer are removed by photoetching, and electrode pads 3c and 3d are formed on the metal base films 3a and 3b, respectively, and the insulation extends from the electrode pad 3c. A comb-shaped electrode 4a is formed on the film 2 and an electrode 4b is formed on the insulating film 2 extending from the electrode pad 3d.

  Subsequently, as shown in FIG. 5, the process proceeds to a step of forming a temperature-sensitive resistance film and a heating resistance film. A thin film thermistor is formed to a thickness of 0.3 to 2.0 μm by sputtering or the like so as to cover the insulating film 2 and the comb-shaped electrodes 4a and 4b formed in the previous step, and a patterning method is performed. A thin film thermistor 5 that becomes a temperature-sensitive resistance film and a thin film thermistor 6 that becomes a heating resistance film are formed on the insulating film 2. The heating resistance film 6 is formed so as to surround the temperature-sensitive resistance film. Thereafter, the thin film thermistors 5 and 6 are heat-treated at a temperature of 400 to 1200 ° C. for 1 to 5 hours. A thin film thermistor to be formed uses a sputtering method with a sintered body of a complex oxide made of manganese, nickel, cobalt, iron, or the like as a target.

  Then, as shown in FIG. 6, it progresses to the process of forming an insulating protective film and the glass protective film mentioned later. First, an insulating protective film 7 made of silicon dioxide (SiO 2), silicon nitride (Si 3 N 4) or the like having a thickness of 0.5 to 2.0 μm is formed on the temperature sensitive resistance film and the heating resistance film. The insulating protective film 7 is formed for the purpose of preventing the reaction between the glass protective film and the thin film thermistors 5 and 6. Further, in order to improve the moisture resistance against the thin film thermistors 5 and 6, a glass paste is applied on the insulating protective film 7 by means such as screen printing, and then the glass protective film 8 is formed by heat treatment at 400 to 800 ° C.

  In addition, although the alumina substrate was used for the substrate of the indirectly heated thermosensitive resistor element of the present invention, a silicon substrate may be used, and as shown in FIG. 7, a thermosensitive resistor film 5 and a heating resistor film 6 are formed. The cavity 9 may be formed on the back surface of the insulating film using a known etching technique. In the indirectly heated thermosensitive element in which the cavity portion 9 is formed in the substrate 1, the heat capacity of the substrate portion on which the temperature sensitive resistance film 5 and the heating resistance film 6 are formed is reduced, and the response speed is improved. Alternatively, a cavity portion may be formed by a method such as cutting on an alumina substrate to reduce the heat capacity of the substrate portion on which the temperature-sensitive resistance film 5 and the heating resistance film 6 are formed, thereby improving the response speed. In addition to the alumina substrate, a ceramic substrate such as aluminum nitride, zirconia, quartz, mullite, and steatite may be used. The heating resistance film 6 is a thin film thermistor, but a metal resistance film such as a platinum resistance thermometer or nichrome resistance may be formed as a heating resistance film.

  The above-mentioned indirectly heated type temperature sensitive resistor element shows the structure of one indirectly heated type temperature sensitive resistor element. In fact, an indirectly heated thermosensitive element assembly substrate in which a number of indirectly heated thermosensitive elements having the above structure are arranged on the substrate is formed, and dicing is performed in order to cut and separate into individual indirectly heated thermosensitive elements. After sticking to a tape or the like, cut using a laser scribing device or a dicing saw. In this way, individual indirectly heated thermosensitive resistors as shown in FIG. 1 are completed. Since each of the divided indirectly heated thermosensitive resistance elements is manufactured in the same batch, variation in resistance value can be reduced, the number of pairing steps can be reduced, and mass production can be achieved.

  Next, an absolute humidity sensor is assembled. First, a method for assembling an absolute humidity sensor in which the above-described indirectly heated temperature sensitive resistance element of the present invention is arranged on the metal CAN shown in FIG. 8 will be described. FIG. 8B is a cross-sectional view taken along YY of FIG. 8A and 8B, a case 20 in which a metal CAN 21A in which a through-hole 21a is formed and a sealed metal CAN 21B are thermally coupled to each other and the two metals CAN 21A and 21B are respectively disposed. The indirectly heated temperature-sensitive resistance elements S1 and S2 are formed. The assembly procedure is as follows. First, the indirectly heated temperature-sensitive resistance elements S1 and S2 are bonded and fixed to the respective stems 22A and 22B of the metal CAN 21A and 21B with a resin-based adhesive, and the temperature-sensitive resistance film is electrically connected by wire bonding. The electrode pad to be led out and the electrode pad to lead out the heating resistive film electrically to the lead 30 of the stem are electrically connected. Next, the caps 23A and 23B and the stems 22A and 22B are bonded to each other, and the cap 23A and the cap 23B are thermally coupled with an adhesive or the like to complete the absolute humidity sensor HS1.

  Further, instead of using the metal CAN, as shown in FIG. 9, an indirectly heated temperature-sensitive resistance element may be arranged in a ceramic package to assemble the absolute humidity sensor HS2. FIG. 9B is a top view when the lid 52 is removed, and FIG. 9C is a cross-sectional view of the absolute humidity sensor cut along ZZ in FIG. 9A. 9A, 9B, and 9C, a partition part 52b is formed in order to form a housing part 51 in which a recessed part 51a formed symmetrically and a through hole 52a and two spaces are formed. It is comprised from the cover part 52 and the side-heat-type thermosensitive resistance element S1, S2. The indirectly heated temperature sensitive resistance elements S1 and S2 are formed on one substrate 1 as shown in the figure. The assembly procedure is as follows. First, the substrate 1 of the indirectly heated thermosensitive resistor elements S1 and S2 is bonded and fixed to the recess 51a of the casing component 51 with a resin adhesive, and the thermosensitive resistor film is electrically derived by wire bonding. The electrode pad 3c, the electrode pad 3d that electrically derives the heating resistance film, and the extraction electrode 53 are electrically connected to each other. Next, the lid 52 is bonded and fixed to the casing component 51 with an adhesive, and the absolute humidity sensor HS2 is completed. In FIG. 9, the indirectly heated type temperature sensitive resistor elements S1 and S2 are formed on one substrate. However, the indirectly heated type temperature sensitive resistor elements S1 and S2 may be separated from each other. In that case, the partition part 52b of the cover part 52 reaches | attains the housing component 51, and becomes a structure which seals S2.

  Next, output characteristics of the absolute humidity sensor will be disclosed. A circuit was connected as shown in FIG. 10A, and output voltages of the absolute humidity sensor HS1 of the present invention and the conventional absolute humidity sensor (FIG. 11) were measured. FIG. 10B shows the result of offsetting the output of the absolute humidity sensor at an atmospheric temperature of 25 ° C. and a relative humidity of 0% and plotting the output of the absolute humidity of 20.75 g / m ^ 3. As can be seen from FIG. 10B, the output voltage of the absolute humidity sensor of the present invention was measured approximately four times, and the detection sensitivity could be improved.

  The present invention is suitable for an absolute humidity sensor used to measure absolute humidity in cooking utensils such as a microwave oven, air conditioning equipment, and various industrial equipment.

It is a figure explaining the side-heat type thermosensitive resistance element concerning this invention. It is a figure explaining the manufacturing process of the indirectly heated type thermosensitive resistance element concerning this invention. It is a figure explaining the manufacturing process of the indirectly heated type thermosensitive resistance element concerning this invention. It is a figure explaining the manufacturing process of the indirectly heated type thermosensitive resistance element concerning this invention. It is a figure explaining the manufacturing process of the indirectly heated type thermosensitive resistance element concerning this invention. It is a figure explaining the manufacturing process of the indirectly heated type thermosensitive resistance element concerning this invention. It is a figure explaining the other example of the side-heat-type thermosensitive resistance element concerning this invention. It is a figure explaining the absolute humidity sensor concerning this invention. It is a figure explaining the other example of the absolute humidity sensor concerning this invention. It is the circuit diagram which measured the output characteristic of the absolute humidity sensor, and a characteristic diagram. It is a figure explaining the conventional absolute humidity sensor. It is a figure explaining the other example of the conventional absolute humidity sensor.

Explanation of symbols

S1, S2 Side-heat type thermosensitive resistor element 1 Substrate 2 Insulating film 3c, 3d Electrode pads 4a, 4b Comb-shaped electrode 5 Temperature sensitive resistor film 6 Heating resistive film 7 Insulating protective film 8 Glass protective film HS1, HS2 Absolute humidity Sensor

Claims (10)

  A substrate, an insulating film formed on the substrate, a temperature-sensitive resistance film formed on the insulating film, and a heating resistance film formed on the insulating film surrounding the temperature-sensitive resistance film; An indirectly heated temperature-sensitive resistor comprising: an electrode pad formed on the substrate for electrically deriving the temperature-sensitive resistor film and the heating resistor film to the outside. element.   A substrate having a cavity formed therein, an insulating film covering the cavity, a temperature-sensitive resistance film formed on the insulating film, and a heating formed on the insulating film surrounding the temperature-sensitive resistance film And an electrode pad formed on the insulating film or the substrate to electrically lead out the temperature-sensitive resistance film and the heating resistance film to the outside. Side-heat-type temperature sensitive resistance element characterized by   The indirectly heated thermosensitive resistor element according to claim 1, wherein the thermosensitive resistor film is formed of a thin film thermistor.   The indirectly heated thermosensitive resistor element according to claim 1, wherein the heating resistive film is formed of a thin film thermistor or a platinum resistance thermometer.   The indirectly heated thermosensitive resistor element according to claim 1, wherein a base electrode layer is formed between the substrate and the electrode pad.   The indirectly heated thermosensitive resistor element according to claim 1, wherein a comb-like electrode is formed between the insulating film, the thermosensitive resistive film, and the heating resistive film.   The indirectly heated type according to claim 1, wherein an insulating protective film is formed on the temperature-sensitive resistive film and the heating resistive film, and a glass protective film is formed on the insulating protective film. Temperature sensitive resistance element.   8. An absolute humidity sensor constructed using the indirectly heated thermosensitive resistor element according to claim 1, wherein two recesses are formed symmetrically and a through hole is formed in one recess, and the case An absolute humidity sensor comprising: the indirectly heated thermosensitive resistor element disposed in each of the recesses; and a lid that closes the indirectly heated thermosensitive resistor element with the case.   In the absolute humidity sensor comprised using the side-heat-type thermosensitive resistance element of Claim 1 thru | or 7, the said side arrange | positioned in each of the case where two recessed parts were formed symmetrically, and the recessed part of this case An absolute humidity sensor comprising a thermo-type temperature sensitive resistance element and a lid for sealing one recess.   8. An absolute humidity sensor configured using the indirectly heated thermosensitive resistor element according to claim 1, wherein a metal CAN in which a through hole is formed and a sealed metal CAN are thermally coupled to each other. An absolute humidity sensor comprising the indirectly heated temperature-sensitive resistance element disposed inside each of the two metals CAN.

Images