JP2021175973A - Resistance type humidity sensor and method of manufacturing resistance type humidity sensor - Google Patents

Abstract

To provide a resistance type humidity sensor that does not require an external component for characteristic adjustment.SOLUTION: A resistance type humidity sensor comprises: a columnar insulation base body 3; a pair of cap-shaped terminals 7, 7 fitted and fixed to both ends of the columnar insulation base body 3; a resistance film 5 formed on a surface of the columnar insulation base body 3 and electrically connected to the pair of cap-shaped terminals 7, 7; a slit 11 formed in the resistance film 5 to divide the resistance film 5 into two; and a humidity sensitive film 13 which is provided to close the slit 11, and varies in resistance value with humidity.SELECTED DRAWING: Figure 1

Description

The present invention relates to a resistance type humidity sensor and a method for manufacturing a resistance type humidity sensor.

In FIG. 2 of JP-A-54-7006 (Patent Document 1), the gap between the two electrodes 2 at both ends of the surface of the hollow cylindrical substrate l is covered from above. A resistance type humidity sensor in which a moisture-sensitive film 3 is adhered to an electrode 2 and the resistance value of the moisture-sensitive film 3 between the gaps is measured by two electrode extraction wires 4 is disclosed.

Further, in FIG. 2 of JP-A-4-364456 (Patent Document 2), a moisture-sensitive element 1 formed in a substantially columnar or substantially cylindrical shape and a gap portion 3 on the surface of the moisture-sensitive element 1 are shown. A humidity sensor including two arranged conductor layers 2 and lead wires 4 provided on the two conductor layers 2 is disclosed. The moisture-sensitive element 1 is a porous ceramic element impregnated with a moisture-sensitive polymer electrolyte.

Japanese Patent Application Laid-Open No. 54-7006, Fig. 2 Japanese Unexamined Patent Publication No. 4-364456 FIG.

If the user of the resistance type humidity sensor uses it without being aware of the rated current, a current exceeding the rated current will flow and the resistance type humidity sensor cannot be used in the correct operating range. In addition, the user may accidentally pass an overcurrent exceeding the allowable current through the resistance type humidity sensor to burn the resistance type humidity sensor.

If an external resistor for characteristic adjustment is required, it is necessary to separately provide an external resistor in the drive circuit.

An object of the present invention is to provide a resistance type humidity sensor that can prevent an excessive current from flowing as much as possible.

Another object of the present invention is to provide a resistance type humidity sensor that does not require an external component for characteristic adjustment.

Another object of the present invention is to provide a method for manufacturing a resistance type humidity sensor which does not require an external component for characteristic adjustment.

The resistance type humidity sensor of the present invention has a columnar insulating substrate, a pair of cap-shaped terminals fixed to both ends of the columnar insulating substrate, and a pair of cap-shaped terminals formed on the surface of the columnar insulating substrate. A resistance film electrically connected to the resistance film, a slit formed in the resistance film so as to divide the resistance film into two, and a moisture-sensitive film provided so as to close the slit and whose resistance value changes according to a change in humidity. Is equipped with. According to the present invention, it is possible to provide a resistance type humidity sensor that can prevent an excessive current from flowing as much as possible. Further, by appropriately setting the resistance value of the resistance film, it is possible to eliminate the need to externally attach the resistor as a separate component for adjusting the characteristics. In the specification of the present application, "dividing into two" is not limited to halving the resistance film in the sense that the resistance film is divided into two.

Theoretically, the moisture-sensitive film may be provided so as to close the slit. However, in the present invention, it may be provided so as to totally cover the resistance film and the slit located between the pair of cap-shaped terminals.

The resistance film preferably does not contain a metal component that causes migration. This is because when the migration extends between the slits, the characteristics of the humidity sensor change due to the occurrence of a short circuit in the divided resistance film.

Further, it is preferable that at least a protective film having a moisture permeability that covers the moisture-sensitive film and protects the moisture-sensitive film is further provided. The protective film may completely cover the resistance film and the moisture-sensitive film between the pair of cap-shaped terminals. By forming such a protective film, it is possible to prevent dust from adhering to the moisture-sensitive film, and it is possible to prevent the moisture-sensitive film and the resistance film from being damaged before mounting on the circuit board.

Further, a pair of lead wires are connected to the pair of cap-shaped terminals, and a plurality of lead wires of the pair of lead wires are bent along the columnar insulating substrate and aligned with the other lead wires. It may be housed in a case having a ventilation hole of. In this case, a pair of lead wires protrude from the case. In the humidity sensor of the present invention, since the pair of lead wires can be used as they are as the fixing means of the case, the number of parts can be reduced.

It is preferable that the pair of cap-shaped terminals and a part of the pair of lead wires continuous with the pair of cap-shaped terminals are covered with a resin coating layer having an insulating property. Further, at least a part of one cap-shaped terminal of the pair of cap-shaped terminals and a part of the lead wire continuous with the one cap-shaped terminal may be continuously covered with an insulating resin coating layer. .. In this way, it is possible to prevent a part of the pair of cap-shaped terminals and the lead wire from being corroded by the moisture-sensitive film that may adhere in the manufacturing process. In addition, it is possible to prevent unnecessary short circuits from occurring.

The present invention divides a columnar insulating substrate, a pair of cap-shaped terminals integrally fixed to both ends of the columnar insulating substrate, a resistance film electrically connected to the pair of cap-shaped terminals, and a resistance film. The subject is a method for manufacturing a resistance type humidity sensor, which comprises a slit formed in the resistance film as described above and a moisture-sensitive film provided so as to close the slit and whose resistance value changes according to a change in humidity. In the present invention, lead wires are connected to the pair of cap-shaped terminals, respectively, and a moisture-sensitive film is formed after the lead wires are connected to the pair of cap-shaped terminals. In this way, the subsequent processing can be continuously performed with the pair of lead wires attached to the guide tapes, so that the manufacturing efficiency can be improved. Further, if a moisture-sensitive film is formed before connecting the lead wire to the pair of cap-shaped terminals, the lead wire is connected with the slit covered with the moisture-sensitive film, which occurs at the time of lead wire connection. , It is possible to prevent the conductive substance contained in the fume from entering the slit and causing variation in characteristics.

If the formation of the resistance film, the formation of the slit, the formation of the moisture-sensitive film, the attachment of the cap-shaped terminal, and the connection of the lead wire are all performed by the automation line, the manufacturing cost can be significantly reduced.

(A) is a diagram showing the cap-shaped terminal as a transparent one in the middle of the manufacturing process of the resistance type humidity sensor of the present embodiment, and (B) is a diagram in which lead wires are welded to both sides of the cap-shaped terminal. It is a figure after applying the moisture-sensitive film, the protective film and the resin coating layer, and (C) is a schematic cross-sectional view which shows the structure of the moisture-sensitive film forming part of the resistance type humidity sensor of this embodiment. It is a figure which shows the characteristic of the said sample of the resistance type humidity sensor of this embodiment. (A) to (J) are diagrams showing the steps of an example of a method in the case of manufacturing a resistance type humidity sensor. (A) and (B) are diagrams showing an example of a shipping form of the resistance type humidity sensor of the present embodiment. (A) is a schematic cross-sectional view showing different structures of the moisture-sensitive film forming portion of the resistance type humidity sensor, and (B) and (C) are views showing another example of applying the resin coating layer, (D). Is a diagram showing different examples of cases.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 (A) is a diagram showing the cap-shaped terminals 7 and 7 as transparent in the middle of the manufacturing process of the resistance type humidity sensor 1 of the present embodiment, and FIG. 1 (B) is a diagram showing the cap-shaped terminals 7 and 7 as transparent ones. It is a figure after the lead wires 9 and 9 were welded on both sides of 7 and 7 and the moisture sensitive film 13, the protective film 15 and the resin coating layer 19 were applied. FIG. 1C is a schematic view showing the structure of the moisture-sensitive film forming portion of the resistance type humidity sensor 1 of the present embodiment. The resistance type humidity sensor 1 in the intermediate state shown in FIG. 1A includes a columnar insulating substrate 3 made of a ceramic material and a resistance film 5 formed on most of the outer peripheral surface of the columnar insulating substrate 3. ing. The resistance film 5 is formed of a resistor material such as ruthenium oxide that does not cause migration. A pair of metal cap-shaped terminals 7 and 7 are fitted to both ends of the columnar insulating substrate 3 so as to come into contact with the resistance film 5. Each of the pair of cap-shaped terminals 7 and 7 is made by plating the surface of an iron cap-shaped main body with Cu and Sn. The cap-shaped terminal 7 is continuous with the opening 7A into which the columnar insulating substrate 3 is fitted, the annular end face portion 7B, and the annular end face portion 7B, and faces the outer peripheral surface of the end portion of the columnar insulating substrate 3. It is provided with a tubular portion 7C to be formed and a curved portion 7D facing the end surface 3A of the end portion of the columnar insulating substrate 3. Further, the resistance film 5 is formed with an annular slit 11 extending over the entire circumference so as to divide the resistance film 5 into two. The shapes of the cap-shaped terminals 7 and 7 are not limited to those provided with the curved portion 7D as in the present embodiment, and follow the end surface of the columnar insulating substrate 3 without providing the curved portion 7D. It may have such an outer shape.

In the examples shown in FIGS. 1B and 1C, a moisture-sensitive film 13 made of an ionic moisture-sensitive polymer whose resistance value changes according to a change in humidity is formed so as to close the slit 11. The moisture-sensitive film 13 includes, for example, a moisture-sensitive polymer as disclosed in Japanese Patent Application Laid-Open No. 2003-4685, and an additive polymer such as polyvinyl alcohol that increases the adhesiveness and water resistance of the moisture-sensitive polymer to the columnar insulating substrate 3. The mixture with and is applied so as to fill the slit 11 and overlap with the resistance film 5, and the coated material is dried and cured to form. In this example, a part of the resistance film 5 between the pair of cap-shaped terminals 7 and 7 and the protective film 15 covering the moisture-sensitive film 13 are further formed. In the present embodiment, the protective film 15 uses the same polymer material as the basic polymer material used for forming the moisture-sensitive film 13. The protective film 15 has moisture permeability and prevents moisture, dust, etc. from directly adhering to the moisture-sensitive film 13.

Theoretically, the moisture-sensitive film 13 may be provided so as to close the slit 11, and the protective film 15 may be provided so as to cover the moisture-sensitive film 13. However, it goes without saying that the moisture sensitive film 13 may be provided so as to totally cover the resistance film 5 and the slit 11 located between the pair of cap-shaped terminals 7 and 7. When the moisture-sensitive film 13 covers the resistance film 5, it is preferable that the moisture-sensitive film 13 does not come into contact with the pair of cap-shaped terminals 7 and 7. In this way, the smaller the size, the lower the adhesive force of the moisture-sensitive film 13 to the resistance film 5, so that the adhesive area of the moisture-sensitive film 13 increases and the moisture-sensitive film 13 can be effectively prevented from peeling off. When the protective film 15 is formed on the moisture-sensitive film 13, it is preferable that the protective film 15 is also formed so as not to come into contact with the pair of cap-shaped terminals 7, 7.

Further, in the present embodiment, a pair of lead wires 9 and 9 are welded and connected to the pair of cap-shaped terminals 7 and 7. Further, a part of the pair of cap-shaped terminals 7 and 7 and the pair of lead wires 9 and 9 is covered with resin coating layers 19 and 19 formed by applying an insulating resin paint made of an epoxy resin. The resin coating layers 19 and 19 have a cap shape when the moisture sensitive film 13 and the protective film 15 come into contact with the cap-shaped terminals 7 and 7 and the lead wires 9 and 9 in the coating process of the moisture sensitive film 13 and the protective film 15. It is possible to prevent the terminals 7 and 7 and the lead wires 9 and 9 from being corroded. In addition, ions in the moisture-sensitive film react and precipitate, and the occurrence of characteristic abnormalities can be suppressed.

The dimensions of the test powder sample of the above embodiment are shown. The length L1 between the ends of the pair of cap-shaped terminals 7 and 7 is about 5.8 mm, and the pair of cap-shaped terminals 7 and 7 have a length L1 of about 5.8 mm. The length between the openings 7A and 7A is about 2.8 mm, the length L2 of the columnar insulating substrate 3 is about 5.5 mm, the diameter D is about 1.5 mm, and the width of the slit is 0.13 ±. It is 0.1 mm. Further, the resistance value of the resistance type humidity sensor 1 is preferably about 1 kΩ to 1000 kΩ in consideration of the balance with the surrounding circuits.

FIG. 2 is a diagram showing the characteristics of the sample of the resistance type humidity sensor of the present embodiment. As can be seen from FIG. 2, the resistance value decreases almost linearly on the logarithmic graph as the humidity increases. By changing the resistance value of the resistance film 5, this characteristic can be shifted as a whole. Incidentally, when the resistance value of the resistance film 5 is lowered, the characteristics are lowered as a whole, and when the resistance value of the resistance film 5 is increased, the characteristics are generally improved.

[Production method]
An example of a method for manufacturing the resistance type humidity sensor having the structure shown in FIGS. 1 (A) to 1 (C) will be described below with reference to FIG. First, the columnar insulating substrate 3 is prepared [FIG. 3 (A)]. Next, the resistance coating material is applied to the columnar insulating substrate 3 and then fired to form the resistance film 5 [FIG. 3 (B)]. The resistance film 5 may be formed in a required range. Then, a pair of cap-shaped terminals 7 and 7 are fitted to both ends of the columnar insulating substrate 3 so as to come into contact with the resistance film 5 [FIG. 3 (C)]. In FIG. 3C, the cap-shaped terminals 7 and 7 are drawn as transparent.

Next, the slit 11 is formed by laser cutting [FIG. 3 (D)]. The laser cutting process is performed by fixing the laser beam and rotating the columnar insulating substrate 3. Next, the lead wires 9 and 9 are welded to the pair of cap-shaped terminals 7 and 7 [FIG. 3 (E)]. Then, the pair of cap-shaped terminals 7 and 7 are coated with an epoxy resin and dried [FIG. 3 (F)], and then the bases of the lead wires 9 and 9 are coated with an epoxy resin and dried to obtain a resin coating layer. 19 is formed [Fig. 3 (G)]. The resin coating layer 19 is formed for the purpose of protection and insulation.

Next, a moisture-sensitive liquid is applied so as to cover the slit 11 and dried to form the moisture-sensitive film 13 [FIG. 3 (H)]. Next, a protective liquid is applied on the moisture-sensitive film 13 and the resistance film 5 so as to cover the moisture-sensitive film 13 to form the protective film 15 [FIG. 3 (I)]. The pair of lead wires 9 may be sandwiched between tapes and taped as they are, but as shown in FIG. 3J, one of the pair of lead wires 9 is bent so as to extend in parallel with the other lead wire 9. May be formed.

When forming is performed as shown in FIG. 3 (J), it may be stored in the case 21 as shown in FIG. 4 (A). In FIG. 4A, the front door 21A of the case 21 is removed so that the inside of the case 21 can be seen. That is, a case in which one lead wire 9 of the pair of lead wires 9 and 9 is bent along the columnar insulating substrate 3 and aligned with the other lead wire 9 and has a plurality of ventilation holes 21B in the front door 21A. It may be stored in 21. When the pair of lead wires 9 and 9 protrude from the case 21 in this way, the pair of lead wires 9 and 9 can be used as they are as the fixing means of the case 21, so that the number of parts can be reduced. Further, in the humidity sensor of the present embodiment, when the resistance value of the resistance film 5 is set to an appropriate value so that it is not necessary to provide a resistor for characteristic adjustment as a separate component, the size of the case 21 is significantly increased. Can be made smaller.

Further, as shown in FIG. 4 (B), two lead wires 9 and 9 can be sandwiched between one pair of taping tapes 22 to form a roll for shipping packaging.

When the moisture-sensitive film 13 is formed after the step of FIG. 3D, the slit 11 and the resistance film 5 are covered with the moisture-sensitive liquid, and then the lead wire 9 is welded to the cap-shaped terminal 7. You may. If the moisture-sensitive film 13 is formed before the lead wires 9 and 9 are connected to the pair of cap-shaped terminals 7 and 7, the lead wires 9 are connected with the slit 11 covered with the moisture-sensitive film 13. , It is possible to prevent the conductive substance contained in the fume, which is generated at the time of lead wire connection, from entering the slit and causing variation in characteristics. The protective film 15 may be formed after the moisture-sensitive film 13 is formed, or may be formed after the lead wires 9 are connected in the same manner as in the manufacturing process of FIG.

[others]
In the above embodiment, the moisture-sensitive film 13 is covered with the protective film 15, but as shown in FIG. 5A, the resistance film 5 located between the pair of cap-shaped terminals 7 and 7 is also a protective film. It may be covered with 15. Further, as shown in FIGS. 5 (B) and 5 (C), at least a part of one cap-shaped terminal 7 of the pair of cap-shaped terminals 7 and 7 and a part of a lead wire 9 continuous with the one cap-shaped terminal. May be continuously coated with the insulating resin coating layer 19. Further, if a convex portion 10 formed by bending one of the lead wires 9 so as to be separated from the other lead wire is provided on one lead wire, the convex portion 10 can be used as a positioning means at the time of mounting on the circuit board. Further, as shown in FIG. 5D, the case 21 may have a cylindrical structure having air permeability. The case 21 having a cylindrical structure having this air permeability may be formed by a heat-shrinkable tube. By using the heat-shrinkable tube, the case 21 can be manufactured at low cost, the case 21 can be easily fixed, and the case 21 can be easily prevented from moving.

Further, the formation of the resistance film 5, the formation of the slit 11, the formation of the moisture-sensitive film 13, the attachment of the cap-shaped terminal 7, and the connection of the lead wire 9 may all be performed by an automated line. In this way, the manufacturing cost can be significantly reduced.

Further, the position of the slit 11 is not limited to the central position of the resistance film 5. Further, the slit 11 is not limited to the case where it is formed orthogonally to the central axis of the columnar insulating substrate 3, and it is needless to say that the slit 11 may be formed in a form not orthogonal to the central axis.

According to the present invention, it is possible to provide a resistance type humidity sensor that can prevent an excessive current from flowing as much as possible. Further, by appropriately setting the resistance value of the resistance film, it is possible to eliminate the need to externally attach a resistor as a separate component for adjusting the characteristics, and the humidity sensor device can be constructed inexpensively and compactly.

1 Resistance type humidity sensor 3 Columnar insulation substrate 5 Resistance film 7 Cap-shaped terminal 9 Lead wire 11 Slit 13 Moisture sensitive film 15 Protective film 19 Resin coating layer 21 Case

Claims (11)

Cylindrical insulating substrate and
A pair of cap-shaped terminals fixed to both ends of the columnar insulating substrate,
A resistance film formed on the surface of the columnar insulating substrate and electrically connected to the pair of cap-shaped terminals.
A slit formed in the resistance film so as to divide the resistance film into two,
A resistance type humidity sensor provided so as to close the slit and provided with a moisture-sensitive film whose resistance value changes according to a change in humidity. The resistance-type humidity sensor according to claim 1, wherein the moisture-sensitive film is provided so as to totally cover the resistance film and the slit located between the pair of cap-shaped terminals. The resistance type humidity sensor according to claim 1 or 2, wherein the resistance film does not contain a metal component that causes migration. The resistance type humidity sensor according to claim 1 or 2, further comprising at least a protective film having moisture permeability that covers the moisture-sensitive film and protects the moisture-sensitive film. The resistance-type humidity sensor according to claim 4, wherein the protective film completely covers the resistance film and the humidity-sensitive film between the pair of cap-shaped terminals. A pair of lead wires are connected to the pair of cap-shaped terminals.
One of the lead wires of the pair of lead wires is housed in a case having a plurality of ventilation holes in a state of being bent along the columnar insulating substrate and in line with the other lead wire.
The resistance type humidity sensor according to any one of claims 1 to 3, wherein the pair of lead wires protrude from the case. The resistance type humidity sensor according to claim 6, wherein the pair of cap-shaped terminals and a part of the pair of lead wires continuous with the pair of cap-shaped terminals are coated with a resin coating layer having an insulating property. A claim that at least a part of one cap-shaped terminal of the pair of cap-shaped terminals and a part of the lead wire continuous with the one cap-shaped terminal are continuously covered with an insulating resin coating layer. Item 6. The resistance type humidity sensor according to Item 6. Cylindrical insulating substrate and
A pair of cap-shaped terminals fixed to both ends of the columnar insulating substrate,
A resistor film electrically connected to the pair of cap-shaped terminals and
A slit formed in the resistance film so as to divide the resistance film into two,
A method for manufacturing a resistance type humidity sensor, which is provided so as to close the slit and includes a moisture-sensitive film whose resistance value changes according to a change in humidity.
Lead wires are connected to the pair of cap-shaped terminals, respectively.
A method for manufacturing a resistance type humidity sensor, which comprises forming the moisture-sensitive film after connecting the lead wire to the pair of cap-shaped terminals. Cylindrical insulating substrate and
A pair of cap-shaped terminals fixed to both ends of the columnar insulating substrate,
A resistor film electrically connected to the pair of cap-shaped terminals and
A slit formed in the resistance film so as to divide the resistance film into two,
A method for manufacturing a resistance type humidity sensor, which is provided so as to close the slit and includes a moisture-sensitive film whose resistance value changes according to a change in humidity.
Lead wires are connected to the pair of cap-shaped terminals, respectively.
A method for manufacturing a resistance type humidity sensor, which comprises forming the moisture-sensitive film before connecting the lead wire to the pair of cap-shaped terminals. 9. How to manufacture a resistance type humidity sensor.

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