JP2021021562A - Humidity detection device - Google Patents

Abstract

To provide a humidity detection device capable of suppressing a decrease in detection accuracy while simplifying a configuration for preventing foreign matter such as dust from adhering to a moisture-sensitive layer.SOLUTION: A humidity detection device 10 is provided with a reference detection unit 10A and a humidity detection unit 10B on a base material 11. The reference detection unit and the humidity detection unit respectively have a moisture-sensitive layer interposed between a first electrode and a second electrode. A front side of the reference detection unit and the humidity detection unit is covered by a lid 21. A first space 23 is formed between the lid and the reference detection unit, and a second space 24 is formed between the lid and the humidity detection unit. The humidity detection unit is provided with a humidity-sensitive hole extending from the second space to the moisture-sensitive layer. The lid is provided with an opening 22 connected to the first space in an area covering the reference detection unit, and the first space and the second space are connected to each other so as to be ventilated by a communication hole.SELECTED DRAWING: Figure 1

Description

The present invention relates to a humidity detection device, and more particularly to a humidity detection device in which a humidity sensitive layer is provided between two electrodes.

As a humidity detection device, a configuration is known in which a humidity sensitive layer is provided between two electrodes and humidity is detected based on changes in capacitance and electrical resistance. In this humidity detection device, since it is necessary to expose the humidity-sensitive layer to the outside air, if foreign matter such as dust contained in the outside air adheres to the humidity-sensitive layer, the accuracy of the detection result will be affected.

Patent Document 1 discloses a humidity sensor using a photocatalytic filter. The photocatalyst filter is a porous filter coated with a photocatalyst, and is provided so as to cover the case opening of the humidity sensor.

Patent Document 2 discloses a humidity sensor in which a protective gel made of a water-resistant material is applied to the upper surface of the sensor element. The protective gel is provided so as to cover the entire circuit portion, the bonding wire, and a part of the portion of the lead terminal protruding inward of the case in the humidity sensor.

Patent Document 3 discloses a capacitive humidity sensor in which a moisture permeable film is provided on the detection unit. This capacitive humidity sensor has a detection unit including a pair of detection electrodes and a moisture-sensitive film formed on the pair of detection electrodes and whose capacitance value changes according to humidity, and the moisture-sensitive film of the detection unit. A gel film as a moisture permeable film is provided on the top.

Japanese Patent No. 4765856 Japanese Patent No. 4765848 Japanese Patent No. 38595950

In a humidity detection device using a moisture-sensitive layer, as described in Patent Documents 1 to 3, a photocatalyst filter, a protective gel, a gel film, etc. are used as a configuration for preventing foreign substances such as dust from adhering to the moisture-sensitive layer. It may be adopted, but even in these cases, it is required to secure a predetermined detection accuracy. Further, even if a configuration for preventing foreign matter from adhering is provided, it is desired to avoid an increase in the number of parts, an increase in cost, and an increase in size of the device.

Furthermore, when a protective gel or gel film is provided, it may not be possible to secure a sufficient film thickness from the viewpoint of ensuring detection accuracy and avoiding an increase in the size of the device. In such a case, foreign matter adheres or invades sufficiently. Difficult to prevent. Further, although the photocatalytic filter is effective in invading tobacco particles and the like, it cannot prevent the invasion of gaseous foreign substances contained in the air because it is a porous filter.

Therefore, an object of the present invention is to provide a humidity detection device capable of maintaining detection accuracy while simplifying a configuration for preventing foreign matter such as dust from adhering to the humidity-sensitive layer.

In order to solve the above problems, the humidity detection device of the present invention is a humidity detection device in which a reference detection unit and a humidity detection unit are provided on a base material, and the reference detection unit and the humidity detection unit are first. A humidity-sensitive layer is interposed between the electrode and the second electrode, the front side of the reference detection unit and the humidity detection unit is covered by the lid, and the first space is between the lid and the reference detection unit. A second space is formed between the lid and the humidity detection unit, the humidity detection unit is provided with a humidity-sensitive hole extending from the second space to the humidity-sensitive layer, and the lid is a reference detection unit. An opening connected to the first space is provided in the area covering the first space, and the first space and the second space are characterized in that they are vertically connected to each other by a communication hole.
According to this humidity detection device, it is possible to prevent foreign matter such as dust from adhering to the humidity-sensitive layer and maintain the detection accuracy by a simple configuration.

In the humidity detection device of the present invention, the lid portion is fixed to the base material by an adhesive layer arranged around the reference detection unit and the humidity detection unit on the base material, and the communication hole is a first space. It is preferable that the adhesive layer penetrates the adhesive layer so as to connect the space with the second space.
As a result, it is possible to easily provide a configuration that can realize both prevention of foreign matter adhesion and maintenance of detection accuracy.

In the humidity detection device of the present invention, it is preferable that the lid portion is formed of silicon and the adhesive layer is formed of a polyimide resin.
As a result, it is possible to easily provide a configuration capable of both preventing foreign matter from adhering and maintaining detection accuracy without complicating the production process and significantly increasing the cost.

According to the present invention, it is possible to provide a humidity detection device capable of maintaining detection accuracy while simplifying a configuration for preventing foreign matter such as dust from adhering to the humidity sensitive layer.

(A) is a plan view showing a schematic configuration of a humidity detection device according to an embodiment of the present invention, and (b) is a plan view showing a state without a lid in the humidity detection device of (a). FIG. 1A is a cross-sectional view taken along the line AA'of FIG. 1A and is a diagram showing a configuration of a reference detection unit. It is a cross-sectional view in line BB'of FIG. 1A and is the figure which shows the structure of the humidity detection part. FIG. 1A is a cross-sectional view taken along the line CC'of FIG. 1A and shows a communication hole.

Hereinafter, the humidity detection device according to the embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1A is a plan view showing a schematic configuration of a humidity detection device 10 according to the present embodiment, and FIG. 1B is a plan view showing a state in which the humidity detection device 10 of (a) does not have a lid 21. .. FIG. 2 is a cross-sectional view taken along the line AA'of FIG. 1A and is a diagram showing the configuration of the reference detection unit 10A. FIG. 3 is a cross-sectional view taken along the line BB'of FIG. 1A and is a diagram showing the configuration of the humidity detection unit 10B. FIG. 4 is a cross-sectional view taken along the line CC'of FIG. 1 (a) and shows a communication hole 25. In FIGS. 2 to 4, the end portion of the base material 11 in the plane direction (horizontal direction in FIGS. 2 to 4) is partially omitted. In the following description, the upper side of FIGS. 2 to 4 is referred to as the front side (upward direction) and the lower side is referred to as the back side (downward direction), but the vertical direction can be arbitrarily set according to the posture of the device and the like.

(Overall configuration of humidity detection device)
As shown in FIGS. 1A and 1B, the humidity detection device 10 is a device including a reference detection unit 10A and a humidity detection unit 10B, and detects the humidity of the outside air as an electric signal. As shown in FIGS. 2 or 3, the reference detection unit 10A and the humidity detection unit 10B are formed on the first insulating layer 12 formed on the sheet-shaped base material 11. For example, silicon is used as the base material 11, and for example, silicon oxide is used as the first insulating layer 12.

As shown in FIG. 1A, the lid portion 21 is arranged so as to cover the front side (upper side of FIGS. 2 to 4) of the reference detection unit 10A and the humidity detection unit 10B. The lid portion 21 is fixed to the base material 11 side by an adhesive layer 20 (see FIG. 1B) arranged around the reference detection unit 10A and the humidity detection unit 10B. As the adhesive layer 20, for example, a polyimide resin is used, and as the lid portion 21, for example, a plate material made of silicon is used.

As shown in FIGS. 1A and 2, in the lid portion 21, an opening 22 is provided in a region covering the reference detection portion 10A. The opening 22 has a substantially square shape when viewed from above the humidity detection device 10. The opening 22 may be formed in advance on the plate material constituting the lid 21, or may be formed by etching after being fixed on the adhesive layer 20. As shown in FIG. 2, the opening 22 is provided so as to penetrate the thickness direction of the lid 21 (vertical direction in FIG. 2) from the front side to the back side. As a result, the first space 23 between the reference detection unit 10A and the lid portion 21 and the opening 22 are connected to each other. Therefore, the first space 23 is connected to the outside of the humidity detection device 10 through the opening 22, and the outside air is introduced into the first space 23.

Here, as shown in FIG. 1A, the opening 22 has a substantially square shape in the plan view according to the shape of the reference detection unit 10A, but the plane shape is not limited to this. Further, the opening area in a plan view can be arbitrarily set according to the specifications of the humidity detection device 10, and can be set larger or smaller than the reference detection unit 10A, for example. Further, it is preferable that the opening 22 is provided so as to overlap the reference detection unit 10A in a plan view. As for the position and range of the opening 22 in a plan view, if it does not reach the end of the lid 21 or does not overlap the humidity detection unit 10B, a part of the opening 22 is a reference detection unit. It may spread or shift outward from 10A. Further, the opening 22 may be divided into two or more.

(Structure of reference detection unit 10A)
As shown in FIG. 2, the reference detection unit 10A includes a first electrode 13, a moisture-sensitive layer 14, and a second electrode 15.
The first electrode 13 is patterned on the first insulating layer 12. The second electrode 15 is patterned apart from the first electrode 13.

The moisture-sensitive layer 14 is provided so as to be interposed between the first electrode 13 and the second electrode 15. That is, the moisture-sensitive layer 14 is formed so as to cover the first electrode 13. A polyimide resin is used as the moisture-sensitive layer 14.

A second electrode 15 is formed on the moisture-sensitive layer 14. The second electrode 15 is provided so as to extend outward from the reference detection unit 10A, more specifically, outward from the region where the adhesive layer 20 and the lid portion 21 are provided in a plan view.

A second insulating layer 16 is provided so as to cover the second electrode 15 and the moisture-sensitive layer 14 between the patterns of the second electrode 15. A first space 23 is formed between the second insulating layer 16 and the reference detection unit 10A covered by the second insulating layer 16 and the lid portion 21 including the opening 22. As the second insulating layer 16, an inorganic material having low hygroscopicity such as silicon nitride is used. The second insulating layer 16 extends to the outside of the reference detection unit 10A, and an opening 16a is provided at the extending destination. A pad electrode 17 is provided on the opening 16a, and the pad electrode 17 conducts with the second electrode 15 through the opening 16a.

(Structure of humidity detection unit 10B)
As shown in FIG. 3, the humidity detection unit 10B includes a first electrode 33, a humidity sensitive layer 34, and a second electrode 35.
The first electrode 33 is patterned on the first insulating layer 12. The second electrode 35 is patterned apart from the first electrode 33. The first electrode 33 and the second electrode 35 are formed with the same thickness and pattern as the first electrode 13 and the second electrode 15 of the reference detection unit 10A.

The moisture-sensitive layer 34 is provided so as to be interposed between the first electrode 33 and the second electrode 35. That is, the moisture-sensitive layer 34 is formed so as to cover the first electrode 33. A polyimide resin is used as the moisture-sensitive layer 34.

A second electrode 35 is formed on the moisture-sensitive layer 34. The second electrode 35 is provided so as to extend outward from the humidity detection unit 10B, more specifically, outward from the region where the adhesive layer 20 and the lid portion 21 are provided in a plan view.

Similar to the reference detection unit 10A, the second insulating layer 16 is provided so as to cover the second electrode 35 and the moisture-sensitive layer 34 between the patterns of the second electrode 35. A second space 24 is formed between the second insulating layer 16 and the humidity detection unit 10B covered by the second insulating layer 16 and the lid portion 21. Here, the humidity detection unit 10B is provided with a plurality of moisture-sensitive holes 36 that penetrate the second insulating layer 16 and the second electrode 35 in the film thickness direction. In other words, the humidity detection unit 10B includes a humidity sensitive hole 36 extending from the second space 24 to the humidity sensitive layer 34. As a result, the air in the second space 24 reaches the humidity-sensitive layer 34 through the humidity-sensitive holes 36. Similar to the second insulating layer 16 in the reference detection unit 10A, the second insulating layer 16 in the humidity detection unit 10B extends to the outside of the humidity detection unit 10B, and an opening 16a is provided at the extension destination. .. A pad electrode 18 is provided on the opening 16a, and the pad electrode 18 conducts with the second electrode 35 through the opening 16a. As shown in FIGS. 1A and 1B, the pad electrode 18 is juxtaposed with the pad electrode 17.

A pad electrode 19 that serves as a ground potential is provided so as to be juxtaposed with the pad electrodes 17 and 18 (see FIGS. 1 (a) and 1 (b)). The pad electrodes 17, 18 and 19 are connected to an integrated circuit (not shown).

A communication hole 25 penetrating the adhesive layer 20 is provided so as to connect the first space 23 and the second space 24 to each other (see FIGS. 1B and 4). The communication hole 25 is formed so as to travel straight between the first space 23 and the second space 24 in a plan view, and becomes a closed space by placing the lid portion 21 on the adhesive layer 20. Since the first space 23 and the second space 24 are communicated with each other by the communication hole 25, the outside air introduced into the first space 23 from the opening 22 reaches the inside of the second space 24 through the communication hole 25. To do. Therefore, since the outside air reaches the humidity-sensitive layer 34 of the humidity detection unit 10B through such a path, the dielectric constant of the humidity-sensitive layer 34 changes according to the amount of water contained in the humidity-sensitive layer 34, and the first electrode The capacitance (electrical characteristic) between the 33 and the second electrode 35 changes.

On the other hand, since the moisture-sensitive layer 14 of the reference detection unit 10A is covered with the second insulating layer 16 having low hygroscopicity, even if outside air is introduced from the opening 22, the amount of water contained is unlikely to change, and the first There is almost no change in capacitance between the 1st electrode 13 and the 2nd electrode 15.

The change in capacitance in the reference detection unit 10A and the humidity detection unit 10B is output to the integrated circuit (not shown) via the pad electrodes 17, 18 and 19, and the detection output from the reference detection unit 10A and the humidity detection. By taking the difference between the detection outputs from the unit 10B, the change in the humidity of the outside air can be detected.

Based on the above configuration, the humidity detection device 10 of the present embodiment has the following effects.
The humidity detection unit 10B has a simple configuration in which the reference detection unit 10A and the humidity detection unit 10B are covered with a lid portion 21 having an opening 22 in the area corresponding to the reference detection unit 10A, while avoiding an increase in size of the device. It is possible to effectively prevent the adhesion and accumulation of foreign matter on the top. Further, since such a simple configuration is adopted, it is possible to suppress a significant increase in the number of parts and the cost. Further, since the outside air can be guided to the humidity-sensitive layer 34 of the humidity detection unit 10B through the communication hole 25, the accuracy of humidity detection can be maintained.

Since the adhesive layer 20 is arranged so as to surround the reference detection unit 10A and the humidity detection unit 10B, the fixing strength of the lid portion 21 can be made uniform in the surface direction of the base material 11. On the other hand, if an opening is provided in the end region of the lid 21 instead of the opening 22, the fixing strength of the lid 21 is weakened around the opening, which is not preferable. Further, if the shape is changed or a member is added to reinforce such a weak portion, the size of the device will be increased. Further, in the configuration in which the through hole is provided along the surface direction of the base material 11 instead of the through hole in the vertical direction such as the opening 22, the manufacturing process is complicated and the introduction of outside air is ensured. Therefore, it is necessary to provide a space around the lid portion 21, which also causes a problem that the size of the device is increased.

Further, since the opening 22 penetrates the lid portion 21 vertically, the communication hole 25 is provided so as to be orthogonal to the vertical direction, that is, along the surface direction of the base material 11. , Foreign matter that has entered the first space 23 from the opening 22 is difficult to move toward the reference detection unit 10A. Further, by setting the cross-sectional shape of the communication hole 25, it is possible to prevent foreign matter from entering the communication hole 25.

In the humidity detection device 10 of the above embodiment, the humidity sensitive layers 14 and 34 are interposed between the first electrodes 13 and 33 arranged on the back side and the second electrodes 15 and 35 arranged on the front side, respectively. , The arrangement of the first electrode, the second electrode, and the moisture-sensitive layer is not limited to this. For example, the first electrode and the second electrode may be juxtaposed on the first insulating layer 12, and a moisture-sensitive layer may be arranged between them. In this case, for example, the first electrode and the second electrode are arranged in a comb-like shape and are alternately arranged.

In addition, the humidity detection unit has a configuration for detecting a change in capacitance between the first electrode and the corresponding second electrode, as well as an electric resistance between the first electrode and the second electrode. It may be configured to detect a change.
Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments, and can be improved or modified within the purpose of improvement or the idea of the present invention.

As described above, the humidity detection device according to the present invention is useful in that the detection accuracy can be maintained while simplifying the configuration for preventing foreign matter such as dust from adhering to the humidity sensitive layer.

10 Humidity detection device 10A Reference detection unit 10B Humidity detection unit 11 Base material 12 First insulation layer 13 First electrode 14 Moisture sensitive layer 15 Second electrode 16 Second insulation layer 16a Openings 17, 18, 19 Pad electrodes 20 Adhesive layer 21 Lid 22 Opening 23 1st space 24 2nd space 25 Communication hole 33 1st electrode 34 Moisture sensitive layer 35 2nd electrode 36 Moisture sensitive hole

Claims (3)

A humidity detection device with a reference detection unit and a humidity detection unit on the base material.
The reference detection unit and the humidity detection unit have a moisture-sensitive layer interposed between the first electrode and the second electrode, respectively.
The front side of the reference detection unit and the humidity detection unit is covered with a lid.
A first space is formed between the lid portion and the reference detection portion, and a second space is formed between the lid portion and the humidity detection portion.
The humidity detection unit includes a humidity-sensitive hole extending from the second space to the humidity-sensitive layer.
The lid portion is provided with an opening connected to the first space in a region covering the reference detection portion.
A humidity detection device characterized in that the first space and the second space are connected to each other by a communication hole so as to be ventilated to each other. The lid portion is fixed to the base material by an adhesive layer arranged around the reference detection unit and the humidity detection unit on the base material.
The humidity detection device according to claim 1, wherein the communication hole penetrates the adhesive layer so as to connect the first space and the second space. The humidity detection device according to claim 2, wherein the lid portion is formed of silicon and the adhesive layer is formed of a polyimide resin.