JP2007115938A - Thin film thermistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film thermistor which improves its dielectric strength performance, is prevented from varying in characteristics due to an external leading terminal connected to a heat-sensitive film and the electrode material of an interdigital electrode, and demonstrates excellent long-term reliability. <P>SOLUTION: The interdigital electrodes of the thin film thermistor used as the electrodes of the heat-sensitive film formed on the one end of the long, thin insulating board, and the heat-sensitive film, are all covered with a glass protective film and configured so as to be isolated from an external atmosphere; the pair of external leading terminals connected to the pair of interdigital electrodes are formed so as to extend outside of the glass protective film; and its dielectric strength can be improved by the above glass protective film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a structure of a thin film thermistor used in a temperature detection sensor used in home electric products such as air conditioners and refrigerators, temperature control devices of various electronic devices, and the like.

  Conventionally, as temperature sensors used in such household electric products and various electronic devices, as shown in FIGS. 7 and 8, there are electrodes having electrodes on both sides of a thermistor chip 18 made of a sintered metal oxide, After the surface mount type thermistor element 19 having terminal electrodes at both ends in the longitudinal direction of the rectangular parallelepiped is sandwiched between the exposed core wires 21a and 21b by peeling off the insulation coating at one end of the two-core parallel insulation coated electric wire 20 After soldering and fixing to the core wire, after applying an insulating material such as epoxy resin around the thermistor chip or thermistor element and thermosetting it, or after soldering the thermistor chip or thermistor element as described above Then, it was inserted into a bottomed pipe, and an insulating material was injected into the surrounding area to be thermally cured to obtain a product.

  However, in a temperature sensor in which electrodes are formed on both surfaces of a plate-shaped element as described above or a surface-mount type thermistor element is sandwiched between core wires of an insulation-coated electric wire, the side portion of the thermistor chip is Since it is exposed, when the resin is directly sealed in the bottomed metal pipe, the distance between the inner wall surface of the pipe and the thermistor cannot be sufficiently separated, resulting in a breakdown voltage failure. As a method of eliminating the occurrence of such a defect, it is necessary to coat the tip of the temperature sensor with an insulating material in advance and form an insulating layer having a certain thickness around the thermistor element. Although this method can eliminate the insulation breakdown voltage defect, there is a drawback that the thermal responsiveness of the temperature sensor after being sealed in the bottomed metal pipe is deteriorated as much as the insulating layer is formed. In addition, since the tip part is coated with an insulating material, the tip part of the wire to which the thermistor element is attached may become thick and cannot be sealed in a pipe or the like, which may cause problems when assembled as a temperature sensor. was there. Furthermore, for the above reasons, the heat capacity varies, and the heat response of the completed temperature sensor fluctuates.

  As a method for solving such a drawback, there is a method using a thin film thermistor chip. A thin film thermistor is a temperature sensor with a structure in which a heat sensitive film made of a metal oxide and an electrode terminal part made of a metal thin film layer are patterned on an insulating substrate using a semiconductor microfabrication technology. As a temperature sensor for a medical catheter or a temperature sensor enclosed in a small pipe, the application is tending to expand. The features of thin film thermistors are that heat sensitive films and metal thin film layers can be formed with high precision control, so there is little variation in electrical characteristics and dimensional accuracy, and there is an advantage that many thin film thermistors can be manufactured in a single production process. . Therefore, when assembling a temperature sensor by enclosing these thin film thermistors in a pipe, the performance of the completed temperature sensor is stable and excellent in reliability because there is no variation in shape. The temperature sensor made as described above has a wide range of uses, and is widely used from a relatively low temperature to a high temperature around 250 ° C.

  However, when it is used at a relatively high temperature as the use application spreads as described above, the heat sensitive film is covered with an insulating protective film or the like and protected against the outside air, but the electrode terminal portion is exposed to the outside air. Since the metal thin film layer constituting the electrode formed on the electrode terminal portion or the heat sensitive film is formed of platinum (Pt), platinum is passed through the contact interface portion between the insulating protective film and the metal thin film layer. Oxygen entered and exited, and this changed the characteristics of the thermosensitive film of the thermistor made of metal oxide, resulting in a high rate of change with time and poor long-term reliability.

  In addition, since the conventional electrode terminal portion does not have a structure that can be connected and fixed to the core wire of the insulation-coated electric wire, an unnecessary force is applied to the connecting portion when it is inserted and fixed in the bottomed pipe as described above. There are drawbacks such as the occurrence of disconnection disconnection, and the efficiency of work is particularly poor when assembling a temperature sensor enclosed in a small-sized pipe or the like.

  An object of the present invention is to provide a highly reliable thin film thermistor that eliminates the above-described drawbacks.

  The present invention has been made in order to achieve the above object, and the invention of claim 1 is directed to an elongated insulating substrate, an insulating film formed on one surface of the insulating substrate, and pattern formation on the insulating film. A pair of comb electrodes formed of a thin metal film layer, a pair of external lead terminal portions extending from ends of the comb electrodes and formed at one end on the insulating substrate, and the comb using the insulating film as a base. A heat-sensitive film made of a metal oxide patterned on a tooth electrode, an insulating protective film that protects the heat-sensitive film, and a glass protective film that covers the insulating protective film excluding the pair of external lead terminal portions This is a thin film thermistor.

  The invention according to claim 2 of the present invention is such that the interval between the tooth portions of the comb electrode is different between a portion close to the pair of external lead terminal portions and a portion away from the pair of external lead terminal portions. The thin film thermistor according to claim 1, wherein the thin film thermistor is formed.

  According to a third aspect of the present invention, the insulating substrate, a pair of electrode pads and an insulating film formed on the insulating substrate, and a pattern formed on the insulating film with the pair of electrode pads as ends. A pair of comb-shaped electrodes made of a thin metal layer, a heat-sensitive film formed on the comb-shaped electrode with the insulating film as a base, an insulating protective film for protecting the heat-sensitive film, the insulating protective film, and the comb A thin film thermistor comprising a glass protective film covering the end of the tooth electrode, wherein a pair of external lead terminal portions extending from the end of the comb electrode on the electrode pad are formed at one end on the insulating substrate. The thin film thermistor according to claim 1, wherein the thermistor is a thin film thermistor.

  In the invention according to claim 4 of the present invention, the first metal base film constituting the pair of external lead terminal portions formed on the insulating substrate is made of titanium (Ti), and is formed on the first metal base film. The thin film thermistor according to claim 1, wherein the formed first electrode thin film and the comb electrode extending from the first electrode thin film are formed of platinum (Pt).

  According to a fifth aspect of the present invention, the second metal base film and the second electrode thin film constituting the pair of electrode pads formed on the insulating substrate are made of titanium (Ti) and platinum (Pt), respectively. The first metal base film and the first electrode thin film constituting the pair of external lead terminal portions are respectively formed of titanium (Ti) and nickel (Ni) or gold (Au), and the comb electrode is formed of platinum (Pt). The thin film thermistor according to claim 3, wherein the thermistor is a thin film thermistor.

  Since the present invention has a structure in which comb-shaped electrodes are provided so as to be opposed to each other in the length direction on an elongated insulating substrate, it is easy to adjust the number of teeth of the comb-shaped electrodes to be formed, and therefore the resistance of the thin film thermistor It is easy to adjust the value. In addition, by providing a large number of the tooth portions by narrowing the interval between the tooth portions, it is easy to finely adjust the resistance value by trimming after the thin film thermistor is completed.

  In addition, the present invention is characterized in that the resistance value after completion as a thin film thermistor can be easily fine-tuned by forming the gaps between the teeth of the comb-shaped electrode roughly in the length direction.

  Furthermore, the present invention provides a pair of external lead terminal portions that are entirely covered with an insulating protective film and a glass protective film, and are connected to one end of the pair of comb-tooth electrodes. Is formed so as to extend to the outside of the glass protective film, so that the comb electrode and the heat sensitive film are shielded from the outside atmosphere, and even if the thin film thermistor is placed in a high temperature atmosphere, the comb Since the reaction between the tooth electrode material and oxygen in the outside air hardly occurs and as a result, the electrical characteristics of the heat sensitive film are stabilized, a thin film thermistor having excellent long-term reliability can be obtained even when used at high temperatures. In particular, when platinum (Pt) having excellent performance as an electrode material for a heat sensitive film is used for a comb electrode, the effect is very large.

  In addition, by providing an insulating film between the insulating substrate and the heat sensitive film, the metal oxide constituting the heat sensitive film is prevented from reacting with the insulating substrate during heat treatment and thermally diffusing into the insulating substrate. It has the effect of stabilizing the electrical characteristics of the.

  Also, when forming the external lead terminal part, a metal base film is provided for the purpose of improving the adhesion to the insulating substrate surface, and electrode peeling due to local heating when connecting the lead wire to the external lead terminal part is prevented. Further, for the comb electrode, the electrode pad is formed in advance so that the end of the comb electrode is positioned, and the external lead terminal portion and the comb electrode are separately formed. The reliability of the thin film thermistor can be improved by improving the adhesion between the end of the lead wire and the insulating substrate and reducing the effect of heat on the comb electrode due to local heating when the lead wire is connected to the external lead terminal. Can be improved.

  The thin film thermistor of the present invention has a structure in which a heat-sensitive film is formed on one end on an elongated insulating substrate and an external lead terminal portion is provided on the other end, and the tip portion of the insulating substrate except the external lead terminal portion is covered with a glass protective film. Therefore, even when encapsulated in a metal pipe, the insulation distance between the inner wall surface of the pipe and the thin film thermistor can be sufficiently maintained, so that the insulation resistance is excellent.

  Hereinafter, a first embodiment of a thin film thermistor according to the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing an appearance of a first embodiment of a thin film thermistor of the present invention. 2 is a cross-sectional view taken along line AA showing one embodiment of a thin film formation step of the thin film thermistor shown in FIG. In the figure, the insulating substrate 1 is made of a ceramic substrate or sapphire substrate such as alumina, aluminum nitride, zirconia, quartz, mullite, steatite having a thickness of about 50 to 300 μm, and the surface has a smoothness of 0.05 μm or less. Use a polished one. The shape of the thin film thermistor shown in FIG. 1 has a width of 0.2 mm and a length of 0.6 mm made of an alumina substrate. First, 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 polished insulating substrate 1 using a sputtering method, a plasma CVD method, or the like with a thickness of 0.1 to 0. The film is formed to 5 μm. Then, patterning is performed using a photoetching method, and an insulating film 2 is formed on the insulating substrate 1 (FIG. 2A). The insulating film 2 is necessary for preventing a reaction between a heat-sensitive film, which will be described later, and the insulating substrate 1 during heat treatment and obtaining stable electrical characteristics as a thin film thermistor. In this embodiment, the insulating film 2 may be provided after a metal base film, which will be described later, is formed on the insulating substrate.

  Next, the process proceeds to a process of forming a metal base film for forming the external lead terminal portion. 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 on the insulating substrate 1 by a method such as sputtering or vapor deposition. Then, a metal thin film layer made of at least one of platinum (Pt), gold (Au), palladium (Pd), or a palladium alloy is sequentially formed. Subsequently, unnecessary portions of the stacked metal thin film layers are removed by a photoetching method, and a pair of first metal base films 3a, 3b and first electrode thin films 3c, 3d are patterned (FIG. 2 ( b)). The first metal base films 3a and 3b are formed so as to be in contact with the end portion of the insulating film 2 or close to the end portion.

  Subsequently, the process proceeds to a step of forming a comb electrode on the external lead terminal portion and the insulating film 2. 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 insulation 2 and the pair of first electrode thin films 3c and 3d. The first metal base films 3a and 3b are formed to improve the adhesion to the insulating substrate 1, and the first metal base films 3a and 3b and the first electrode thin films 3c and 3d thereon. The total thickness is about 0.1 to 0.5 μm. After the metal thin film layer is formed, unnecessary portions of the metal thin film layer are removed by a photoetching method, and a pair of external lead terminals are provided on the first metal base films 3a and 3b and the first electrode thin films 3c and 3d. A pair of comb electrodes 6a and 6b extending from the portions 5a and 5b and the external lead terminal portions 5a and 5b and facing the insulating film 2 are patterned (FIG. 2C). Reference numerals 7a and 7b denote tooth portions of the comb electrodes 6a and 6b.

  Thereafter, the process proceeds to a step of forming a heat sensitive film. A heat-sensitive layer 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-tooth electrodes 6a and 6b formed in the previous step, and a patterning method is used. A heat sensitive film 4 is patterned on the insulating film 2 (FIG. 2D). Thereafter, the heat sensitive film 4 is heat-treated at a temperature of 400 to 1200 ° C. for 1 to 5 hours. The heat-sensitive layer to be formed is formed on an insulating substrate using a sputtering method using a composite oxide sintered body made of manganese, nickel, cobalt, iron, or the like as a target. When it is necessary to finely adjust the electrical characteristics of the heat sensitive film 4, a second heat sensitive film (not shown) is formed on the heat sensitive film 4 and the electrical characteristics are adjusted by adjusting the thickness of the heat sensitive film. Can do. The second means for adjusting the electrical characteristics of the heat sensitive film is not shown, but after the first heat sensitive film is patterned on the insulating film 2 in FIG. 2 (c), comb-shaped electrodes are formed on the heat sensitive film. Form. Further, it is possible to finely adjust the characteristics by forming a second heat-sensitive film having a thickness adjusted on the comb electrode. That is, the comb electrode is sandwiched between the first and second heat sensitive films.

  Then, it progresses to the process of forming an insulating protective film and the glass protective film mentioned later. In order to prevent the reaction between the glass protective film and the heat-sensitive film, an insulating protective film 8 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 in a pattern. Furthermore, in order to improve the moisture resistance to the heat sensitive film 4 and reduce the influence of the outside atmosphere, a glass paste is applied on the insulating protective film 8 by means of screen printing or the like, followed by heat treatment at 400 to 800 ° C. to protect the glass. A film 9 is formed (FIG. 2E). In addition to the screen printing method, the glass protective film 9 is formed by forming an insulating protective layer and a glass film layer made of silicon dioxide (SiO2), silicon nitride (Si3N4) or the like on the entire substrate, and then patterning by photoetching. And the glass protective film 9 may be formed simultaneously.

  The thin film thermistor described above shows the structure of one thin film thermistor. Actually, a thin film thermistor aggregate substrate in which a large number of thin film thermistors having the above structure are arranged on an insulating substrate is formed, and is cut and separated into individual thin film thermistor chips. Cut with a saw. Thus, individual thin film thermistor chips as shown in FIG. 1 are completed.

  The thin film thermistor shown in FIGS. 1 and 2 has a structure in which the intervals between the tooth portions 7a and 7b of the comb electrodes 6a and 6b are equal, but as shown in FIG. 3, the interval between the tooth portions 7a and 7b. May be a thin film thermistor formed unevenly. In the case of the thin film thermistor as shown in FIG. 3, since the resistance value is low in the portion where the distance between the tooth portions 7a and 7b is formed, the final resistance value adjustment is performed precisely by trimming this portion. be able to. The structure in FIG. 3 is substantially the same as that in FIGS. 1 and 2 except that the intervals between the teeth 7a and 7b of the comb electrodes 6a and 6b are not uniform as described above. Description is omitted.

  Next, another embodiment of the thin film thermistor of the present invention having a structure with stable electrical characteristics that can be used in a relatively high atmosphere will be described.

  FIG. 4 is a perspective view showing the appearance of another embodiment of the thin film thermistor of the present invention. 5 is a cross-sectional view showing an embodiment of a thin film formation step of the thin film thermistor shown in FIG. 4, and is a cross-sectional view taken along the line BB of FIG. In the figure, the insulating substrate 1 is made of a ceramic substrate or sapphire substrate such as alumina, aluminum nitride, zirconia, quartz, mullite, steatite having a thickness of about 50 to 300 μm, and the surface has a smoothness of 0.05 μm or less. Use a polished one. The shape of the thin film thermistor shown in FIG. 4 has a width of 0.2 mm and a length of 0.6 mm made of an alumina substrate. First, an insulating layer 2 made of silicon dioxide (SiO 2), silicon nitride (Si 3 N 4) or the like is formed on one surface of the polished insulating substrate 1 using a sputtering method, a plasma CVD method, or the like with a thickness of 0.1 to 0. The film is formed to a thickness of 0.5 μm and patterned using a photoetching method to form a base layer for forming a thermal film on the insulating substrate 1 (FIG. 5A). The insulating film 2 is necessary for preventing a reaction between a heat-sensitive film, which will be described later, and the insulating substrate 1 during heat treatment and obtaining stable electrical characteristics as a thin film thermistor.

  Next, the process proceeds to a step of forming an electrode pad 12 for connecting a comb-tooth electrode and an external lead terminal portion, which will be described later. Metal thin film layers 10 and 11 are sequentially formed on the insulating substrate 1 by a method such as sputtering or vapor deposition (FIG. 5B). The metal thin film layer 10 formed on the insulating substrate 1 is a metal thin film made of at least one of titanium (Ti), chromium (Cr), nickel (Ni), tungsten (W), tantalum (Ta), and Ni—Cr alloy. Further, a metal thin film layer 11 made of at least one of platinum (Pt), gold (Au), palladium (Pd), palladium alloy, and the like is formed on the metal thin film layer 10. The metal thin film layers 10 and 11 are formed continuously in a vacuum chamber so that a peeling layer such as an oxide film is not formed at the boundary between the metal thin film layers 10 and 11. The metal thin film layer 10 is formed to improve the adhesion to the insulating substrate 1, and the total thickness of the metal thin film layer is about 0.1 to 0.5 μm.

  Subsequently, unnecessary portions of the metal thin film layers 10 and 11 are removed by a photoetching method, and electrode pads 12a and 12b composed of the second metal base films 10a and 10b and the second electrode thin films 11a and 11b are patterned. (FIG. 5C). 5C is a cross-sectional view taken along the line AA of FIG. 5, the second metal base film 10b, the second electrode thin film 11b, and the electrode pad 12b are not displayed on the drawing, but the electrode pad 12b Is formed on the comb electrode 6b side in the same manner as the electrode pad 12a.

  Next, it progresses to the process of forming a comb-tooth electrode. First, at least one metal thin film layer made of platinum (Pt), palladium (Pd), palladium alloy, gold (Au) or the like is formed on the entire substrate by a method such as sputtering, ion plating, or vapor deposition. After the film formation, the formed metal thin film layer is patterned using a photo-etching method to pattern the end portions 14a and 14b extending from the electrode pads 12a and 12b and the comb-tooth electrodes 13a and 13b (FIG. 5E )). In the present embodiment, the comb electrodes 13a and 13b may be provided after the heat-sensitive film is first patterned on the insulating substrate.

  Then, it progresses to the process of forming a thermal film. A heat-sensitive layer is formed to a thickness of 0.3 to 2.0 μm over the entire substrate by sputtering or the like so as to cover the insulating film 2 formed in the previous step, and is formed on the insulating film 2 using a patterning method. The heat sensitive film 4 is patterned (FIG. 5D). Thereafter, the heat sensitive film 4 is heat-treated at a temperature of 400 to 1200 ° C. for 1 to 5 hours. The heat-sensitive layer to be formed is formed on an insulating substrate using a sputtering method using a composite oxide sintered body made of manganese, nickel, cobalt, iron, or the like as a target. When it is necessary to finely adjust the electrical characteristics of the heat sensitive film 4, a second heat sensitive film (not shown) is formed on the heat sensitive film 4 to adjust the electrical characteristics by adjusting the thickness of the heat sensitive film. be able to.

  Then, it progresses to the process of forming an external extraction terminal part. First, titanium (Ti), chromium (Cr), copper (Cu), nickel (Ni), molybdenum (Mo), tungsten (W), gold (Au), Ni—Cr alloy, Ni—Ti alloy, etc. A first metal thin film layer made of at least one of the above and a second metal thin film layer made of at least one of gold (Au), nickel (Ni) or Ni—Cr alloy are formed by a method such as sputtering, ion plating or vapor deposition. . After the film formation, unnecessary portions of the first and second metal thin film layers are removed, and external lead terminal portions 17a and 17b composed of the third metal base films 15a and 15b and the third electrode thin films 16a and 16b are formed into electrode pads. Patterns are formed so as to be connected to the end portions 14a and 14b of 12a and 12b (FIG. 5 (f)).

  Next, it progresses to the process of forming an insulating protective film and the glass protective film mentioned later. In order to prevent the reaction between the glass protective film and the heat-sensitive film, an insulating protective film 8 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 in a pattern. Furthermore, in order to improve the moisture resistance to the heat sensitive film 4 and reduce the influence of the outside atmosphere, a glass paste is applied on the insulating protective film 8 by means of screen printing or the like, followed by heat treatment at 400 to 800 ° C. to protect the glass. A film 9 is formed (FIG. 5G). In addition to the screen printing method, the glass protective film 9 is formed by forming an insulating protective layer and a glass film layer made of silicon dioxide (SiO2), silicon nitride (Si3N4) or the like on the entire substrate, and then patterning by photoetching. And the glass protective film 9 may be formed simultaneously.

  Among the combinations of the various metal thin film layers described above, the second and third metal base films 10a, 10b, 15a, 15b are titanium (Ti), the second electrode thin films 11a, 11b, the comb electrodes 13a, 13b, and the ends. Regarding the thin film thermistor having the structure of the present invention in which platinum (Pt) is used as the portions 14a and 14b and the third electrode thin films 16a and 16b serving as the external lead terminal portions are formed with nickel (Ni) or gold (Au) As a result of long-term reliability and mechanical tests, it was found that excellent performance was obtained.

  The structure of the thin film thermistor described above shows the structure of one thin film thermistor, but in reality, a thin film thermistor aggregate substrate in which a number of thin film thermistors having the structure described above are arranged on an insulating substrate is formed. Thereafter, the thin film thermistor aggregate substrate is cut into strips as shown in FIG. 6, and a lead wire such as a predetermined wire is connected to the external lead terminal portion by a method such as soldering or conductive adhesive, and finally the thin film Each sensor is completed by dividing along a groove formed between the thermistor chips. This method is highly efficient because the work can be performed with a plurality of thin film thermistor chips arranged in a strip shape. Of course, after attaching the thin film thermistor assembly substrate to dicing tape, etc., it is cut and separated using a laser scribing device or dicing saw, etc., and assembled by attaching lead wires etc. using those formed on each thin film thermistor chip May be.

It is a perspective view which shows the external appearance of 1st Embodiment of the thin film thermistor of this invention. It is sectional drawing which shows one Embodiment of the manufacturing process of the thin film thermistor shown in FIG. It is a perspective view which shows the external appearance of the thin film thermistor of a structure where the space | interval of the tooth | gear part of the comb electrode of FIG. 1 differs. It is a perspective view which shows the external appearance of other embodiment of the thin film thermistor of this invention. It is sectional drawing which shows one Embodiment of the manufacturing process of the thin film thermistor shown in FIG. It is a perspective view which shows the external appearance of the board | substrate with which the some thin film thermistor arranged in strip shape was formed. It is a perspective view of the conventional temperature sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Insulating film 3a, 3b 1st metal base film 3c, 3d 1st electrode thin film 4 Thermal sensitive film 5a, 5b External lead-out terminal part 6a, 6b Comb electrode 7a, 7b Tooth part 8 Insulating protective film 9 Glass protective film 10a, 10b 2nd metal base film 11a, 11b 2nd electrode thin film 12a, 12b Electrode pad 13a, 13b Comb electrode 14 End 15a, 15b 3rd metal base film 16a, 16b 3rd electrode thin film 17a, 17b External extraction terminal Part

Claims (5)

  An elongated insulating substrate, an insulating film formed on one surface of the insulating substrate, a pair of comb-shaped electrodes made of a metal thin film layer patterned on the insulating film, and extending from an end of the comb-shaped electrode A pair of external lead terminal portions formed at one end on the insulating substrate, a heat-sensitive film made of a metal oxide patterned on the comb-tooth electrode with the insulating film as a base, and an insulation for protecting the heat-sensitive film A thin film thermistor comprising: a protective film; and a glass protective film covering the insulating protective film excluding the pair of external lead terminal portions.   The interval between the tooth portions of the comb electrode is formed so that the interval is different between a portion close to the pair of external extraction terminal portions and a portion apart from the pair of external extraction terminal portions. Item 2. The thin film thermistor according to item 1.   A pair of comb electrodes comprising the insulating substrate, a pair of electrode pads and an insulating film formed on the insulating substrate, and a metal thin film layer patterned on the insulating film with the pair of electrode pads as ends. A heat-sensitive film formed on the comb-shaped electrode with the insulating film as a base, an insulating protective film for protecting the heat-sensitive film, and a glass protective film for covering the end portions of the insulating protective film and the comb-shaped electrode 2. A thin film thermistor comprising: a pair of external lead terminal portions extending from an end portion of the comb-shaped electrode on the electrode pad at one end on the insulating substrate. The thin film thermistor described in 1.   A first metal base film that constitutes the pair of external lead terminal portions formed on the insulating substrate is made of titanium (Ti); a first electrode thin film formed on the first metal base film; 3. The thin film thermistor according to claim 1, wherein the comb electrode extending from the one electrode thin film is made of platinum (Pt). The second metal base film and the second electrode thin film constituting the pair of electrode pads formed on the insulating substrate are made of titanium (Ti) and platinum (Pt), respectively, and constitute the pair of external lead terminal portions. The first metal underlayer and the first electrode thin film are formed of titanium (Ti) and nickel (Ni) or gold (Au), respectively, and the comb-shaped electrode is formed of platinum (Pt). The thin film thermistor described in 1.

Images