JP5120966B2 - Extremely small amount of moisture measuring element and moisture-proof sealing performance evaluation method using the measuring element - Google Patents

Description

  The present invention is a measurement technology that measures the trace amount of water contained in a space with high sensitivity in a short time, and also measures the permeated moisture of a membrane such as a polymer material or inorganic oxide with high accuracy and high sensitivity in a short time. The present invention relates to a moisture-proof sealing evaluation technique for evaluating the moisture-proof sealing performance of the film.

  Electroluminescent devices (organic EL devices) that use organic material thin films for active layers are pixels for flat panel displays that replace liquid crystal and plasma systems because of their high light emission visibility and the ability to design extremely thin devices. Application is expected. In order to realize displays using organic EL elements that are unstable even with a slight amount of moisture, the development of sealing materials and methods that prevent the entry of extremely small amounts of moisture into the display is an important issue. It has become one. As a highly moisture-proof sealing method, a moisture absorbing material is enclosed in a metal can, or a moisture barrier multilayer film in which a polymer and silica are laminated in multiple layers is bonded to a substrate with an appropriate adhesive and sealed. A method of forming a stop layer has been tried, but from the viewpoint of consistency of the display panel manufacturing process, light extraction efficiency, and further lighter and thinner panel, by vapor deposition methods such as sputtering and CVD methods, Development of a sealing method in which a sealing layer against moisture is directly formed on an organic EL element as a thin film has also been studied.

On the other hand, the development of a quantitative measurement method for trace moisture entering the sealed element has been delayed. Measure the moisture permeability in the thickness direction of the moisture barrier film material described above by the measuring method shown in JIS K7129 or ASTM F1249-90 or the Mocon water vapor permeability measuring device according to them. The measurement sensitivity of about 10 ⁻⁵ grams / square meter · day is achieved, but these methods can only perform accurate measurements only with members that can exist independently as films or membranes. At present, there is no effective moisture permeability measurement method for materials that are difficult to handle as a self-supporting film such as a thin film of a sealing layer directly formed on an organic EL element by vapor deposition or the like. In addition, it has been pointed out that moisture penetration can occur not only in the thickness direction of the sealing layer, but also from the interface between the sealing layer and the organic EL element substrate, both in the case of bonding and in direct film formation sealing. Yes. Therefore, at present, the effective moisture-proof sealing performance of the sealing measures taken for the element cannot be sufficiently evaluated only by measuring the moisture permeability in the film thickness direction of the sealing material.

  As a conventional moisture detecting element, for example, an electrolytic hygrometer for detecting a moisture concentration in a gas flow used in a semiconductor process, the first and second thin films formed spirally on the inner surface of a hollow glass tube A moisture detector capable of detecting moisture in the atmosphere from a ppm level to a high humidity level, comprising an electrode and a water-absorbing film deposited on the entire inner surface of the glass tube (see Patent Document 1), A porous anode, a porous cathode, an electrolyte layer provided between both electrodes, and the like (see Patent Document 2) are known.

Japanese National Patent Publication No. 11-510605 JP 2004-77301 A

As described above, the moisture permeability measurement in the thickness direction of the sealing layer that can exist independently is insufficient for evaluation of a sealing material and a sealing method effective for practical use of an organic EL display. In addition, the electrolytic hygrometer described in Patent Document 1 as a conventional moisture detection element is not a compact one that can be used for evaluation of a sealing layer of an EL element, and a water-absorbing film is applied to the inner surface of a glass tube. Therefore, it is difficult to measure moisture with high accuracy in a short time. The moisture detector described in Patent Document 2 has a measurement limit of several ppm, and cannot be used for highly sensitive moisture detection on the order of 1 ppb as the subject of the present invention.
Since such problems exist in the prior art, it is assumed after forming various types of moisture-destroying objects that dislike moisture such as organic EL elements after taking a sealing measure or similar sealing structures. The development of a new measurement method that captures trace amounts of moisture entering through various routes and performs quantitative measurement with high accuracy and high sensitivity in a short time is desired.

  Against the background of the prior art as described above, the object of the present invention is to provide moisture sealing performance to dehumidifying objects such as organic EL devices and electronic devices that need to be sealed against the entry of a very small amount of moisture. Provides a new moisture detection principle that has sufficient sensitivity for the evaluation of water and can detect moisture accurately in a short time, and a new measurement method that enables quantitative evaluation of the moisture-proof performance of sealing measures There is to do.

In the present invention, trace moisture is detected by using a water absorption layer in which a suitable water absorbing material that absorbs moisture with high efficiency and irreversibly is formed in a thin film on a pair or a plurality of pairs of counter electrodes formed on a substrate. This is performed using an element having the provided structure. The inventor makes the water absorption layer thin in the range of 10 to 100 nanometers so that the water absorption layer efficiently absorbs a very small amount of water molecules, and in this state, applies a voltage to the counter electrode. The amount of water in the water absorption layer can be electrolyzed with high efficiency and the amount of substance calculated from the amount of current flowing at that time can be accurately quantified. It has been found that the measurement accuracy is further improved by using the deposited thin film (V).
That is, the present invention is based on the above knowledge and is characterized by the following matters.
(1) A trace amount moisture detecting element including a pair or a plurality of pairs of counter electrodes formed on a substrate and a water absorbing layer of a water absorbing material formed in contact with the counter electrode, wherein the water absorbing layer includes: It is a deposited thin film of phosphorus oxide (V) having a thickness of 10 to 100 nanometers, and is configured such that a voltage for electrolyzing a very small amount of water absorbed in the water absorption layer is applied between the counter electrodes. A trace amount moisture detecting element characterized by that.
(2) A trace moisture detector including a pair or a plurality of pairs of counter electrodes formed on a substrate and a water absorbing layer of a water absorbing material formed in contact with the counter electrode, wherein the water absorbing layer includes: It is a deposited thin film of phosphorous oxide (V) with a thickness of 10 to 100 nanometers. It absorbs the trace amount of water present around the water absorption layer with the water absorption layer and applies a voltage between the counter electrodes to perform electrolysis. By doing so, an extremely small amount of moisture detecting device is configured to detect and quantify extremely small amounts of moisture.
(3) Forming a sealing layer made of a moisture-proof material that covers the water-absorbing layer on the trace moisture detector described in (1) above, and detecting and quantifying trace moisture with the trace moisture detector. The moisture-proof sealing performance evaluation method for evaluating the moisture-proof sealing performance of the sealing layer.
(4) A moisture-proof sealing layer that seals both the trace moisture detector described in (1) above and an electronic device that requires moisture-proof sealing is formed, and trace moisture is removed by the trace moisture detector. A moisture-proof sealing performance evaluation method for evaluating the moisture-proof sealing performance of the moisture-proof sealing layer by detecting and quantifying.
(5) Applying a sealing agent surrounding the water-absorbing layer to the substrate of the trace moisture detecting element according to (1) above, and capping the space surrounded by the sealing agent with a sheet of moisture-barrier material. A moisture-proof sealing performance evaluation method for evaluating the moisture-proof sealing performance of the sealant by detecting and quantifying trace amounts of moisture with the trace amount moisture detecting element.
(6) The moisture-proof sealing performance evaluation according to any one of (3) to (5) above, wherein a plurality of pairs of counter electrodes of the trace moisture detection element are used and the moisture-proof sealing performance distribution according to the distribution of the counter electrodes is evaluated. Method.

Since the thickness of the water absorption layer is a thin film in the range of 10 to 600 nanometers, the trace moisture measuring element of the present invention can measure the surrounding trace moisture with high sensitivity in a short time. Further, by forming the water-absorbing layer as a deposition thin film of phosphorus oxide (V), the film thickness is uniform and the surface is smooth, and it is possible to measure with high sensitivity and high accuracy with little variation.
An element composed of the counter electrode and the thin film water-absorbing layer is formed on the same type of substrate used for an electronic element requiring a moisture-proof sealing measure or on an actual electronic element, and on the other hand, the same sealing as the electronic element is formed. Regardless of whether or not the sealing layer can exist as a self-supporting film by performing the countermeasure, it is possible to measure not only the thickness direction of the sealing layer but also the moisture entering from the sealing layer-substrate interface. It is possible to evaluate the effective sealing performance of the sealing measures taken.
In addition, in the case where various types of moisture-destroying objects that dislike moisture are sealed with a surrounding sealing agent and a cap of a moisture barrier sheet, the effective sealing performance of the sealing method can be evaluated.

It is a figure which shows the outline of the trace amount water | moisture content measuring element of this invention which makes a water absorption layer absorb a trace amount water | moisture content, and carries out measurement and quantification with the electric quantity of electrolysis. It is a figure which shows the outline of the method of performing the moisture-proof sealing performance evaluation of the sealing layer of electronic devices, such as an organic EL element, using the trace amount moisture measuring element outlined in FIG. It is a figure which shows the outline of the method of laminating | stacking the trace amount moisture measuring element schematically shown in FIG. 1 on an organic EL element, and performing the moisture-proof sealing performance evaluation of a sealing layer. It is a figure which shows the outline of the method of performing the moisture-proof sealing performance evaluation of the sealing method by the sealing agent and the cap of a glass plate using the trace amount moisture measuring element outlined in FIG. The trace amount moisture measuring element 1 produced in Example 1 was installed in a sealed container, and the pressure inside the container was increased stepwise from less than 1 × 10 ⁻⁴ Pascals with a 5 volt voltage applied to the electrodes. It is a figure which shows the change of the output electric current value of the trace amount moisture measuring element 1 at the time. FIG. 5 is an enlarged view of a portion of an elapsed time of change of the output current value shown in FIG. 4 from 5 minutes to 35 minutes. The trace amount moisture measuring element 1 produced in Example 1 is placed in a sealed container, and a voltage of 10 volts is applied to the electrode under a pressure of 1 × 10 ⁻⁴ Pascal or less, so that the moisture absorbed in advance by the water absorption layer is sufficiently obtained. After dehydrating by electrolysis, the voltage application was stopped, and immediately after that, the internal pressure of the container was rapidly increased to 2 × 10 ⁻³ Pascal, the device was exposed for a certain time, and the internal pressure of the container was again reduced to 1 × 10 ⁻⁴ Pascal or less. It is the figure which showed the exposure time dependence of the time attenuation | damping of the output electric current amount which applied the voltage of 10 volts to the electrode after having decreased rapidly and was measured. It is the figure which showed the exposure time dependence at the time of integrating the output current of the trace amount moisture measuring element 1 shown in FIG. The output current value of the moisture measuring element 1 when the moisture measuring element 1 produced in Reference Example 1 is installed in a sealed container and the pressure inside the container is increased stepwise with a voltage of 5 volts applied to the electrodes. It is a figure which shows a change.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of a basic form of a trace amount moisture detecting element of the present invention. A substrate (110), a counter electrode (120) supported by the substrate, and a water absorption layer (in contact with the counter electrode) 130).

  The substrate (110) may be formed of any material as long as the surface supporting the counter electrode (120) and the water absorption layer (130) is electrically insulative. , Plastic film, ceramic sheet, semiconductor wafer and the like. In addition, an element substrate such as an EL element that is actually subjected to a sealing measure can be used as a substrate for an extremely small amount of moisture detecting element without using a substrate dedicated to the extremely small amount of moisture detecting element. In that case, the accuracy of the sealing performance evaluation can be improved.

  The counter electrode (120) is an electrode formed on the substrate and facing each other, and is configured such that a voltage can be applied between the counter electrodes via an electrode lead or the like. The material constituting the counter electrode is not particularly limited as long as it has low resistance and has stability that hardly causes chemical changes such as elution with respect to electrolysis of water. For example, gold, platinum, palladium, etc. Examples include noble metals and glassy carbon thin films. The counter electrode may be a pair of a positive electrode and a negative electrode, but the efficiency of water electrolysis can be increased by forming a plurality of pairs of the positive electrode and the negative electrode. When a plurality of pairs of positive and negative electrodes are used, for example, the electrodes are opposed to each other in a comb shape, and the comb-shaped comb teeth are arranged alternately. It is also possible to measure the quantity collectively. Further, each counter electrode may be arranged independently of each other, and for each counter electrode, one or both of voltage application and electric quantity measurement may be performed independently. In the measurement region, it is possible to measure the moisture distribution and the moisture-proof sealing performance distribution according to the counter electrode distribution. The planar shape of each electrode is not limited to a linear shape, but may be any shape such as a spiral shape or a curved shape such as a (concentric) arc shape. The thickness and width of the counter electrode (120) need only be sufficient to ensure sufficient conductivity. The thickness is usually about 10 nanometers to 1 micron, and the flatness of the water-absorbing material thin film to be laminated immediately above is sufficient. When considering not to have an influence, about 10 to 100 nanometers, more preferably about 30 to 70 nanometers, and the width is about 5 to 200 microns from the viewpoint of compactness. Preferably, the thickness is about 20 to 100 microns. The length of the counter electrode can be appropriately set according to the object such as an EL element, but from the viewpoint of compactness, the length is preferably about 50 to 10 millimeters, preferably about 200 to 5 millimeters. The interval between the positive electrode and the negative electrode can be arbitrarily set depending on the voltage to be applied, but for convenience of measurement, in order to apply a large electric field between the electrodes even at a low applied voltage, about 10 to 1000 microns, more preferably 20 to 20 microns. It is good to set in the range of about 500 microns. The counter electrode can be formed by a known method such as vacuum deposition.

The water-absorbing layer (130) is formed of a thin film of a water-absorbing material that absorbs moisture present in the surroundings, and is formed so as to be in contact with both the positive and negative electrodes of the counter electrode. When multiple pairs of counter electrodes are used, a single large-area water-absorbing layer may be formed so as to be in contact with all the counter electrodes. However, when measuring the moisture-proof sealing performance distribution, each counter electrode is separately provided. It is preferable to form a water absorbing layer. As the water-absorbing substance, it is preferable to use a material that reacts efficiently with water molecules and that irreversibly absorbs water molecules that hardly re-release due to changes in pressure or temperature. Moreover, when water molecules are not absorbed, it behaves as a high-resistance insulator, which is convenient for reducing the dark current with respect to the electrolysis current of water at the time of measurement and improving the quantitative accuracy. An example of a water-absorbing substance that satisfies these properties is phosphorus oxide (V). The moisture irreversibly absorbed by the water-absorbing substance is electrolyzed by applying a predetermined voltage between the counter electrodes that are in contact with the water-absorbing substance, and is released according to the amount of electricity at that time. The thickness of the water-absorbing layer (130) may be any thickness as long as no gap is generated between the counter electrode and the water-absorbing layer (130), but it is measured by shortening the time until the absorbed water molecules reach the electrode as much as possible. In view of the point that the time responsiveness of the device can be improved and the element structure for detecting the trace amount of moisture of the present invention does not affect the smooth formation of the sealing layer when evaluating the sealing performance. Although it is advantageous to make it as thin as possible, if it is less than 10 nanometers, it may be difficult to form a water-absorbing layer having a uniform and smooth surface. Depending on the thickness of the electrode, it is 10 to 600 nanometers. In this case, it is preferably adjusted in the range of 20 to 100 nanometers. The thin film of the water absorbing layer can be formed by a known method such as heating vacuum deposition or applying a solution in which a water absorbing material is dissolved in an appropriate solvent, but from the viewpoint of forming a thin film with a uniform and smooth surface, Vacuum deposition is preferred.
The trace moisture detecting element of the present invention can be made compact when used for evaluation of a sealing layer of an EL element. In that case, each detecting element is, for example, 10 mm ² or less or 3 mm ^2. The area of each counter electrode of the detection element including a plurality of counter electrodes can be, for example, 10 mm ² or less or 3 mm ² or less.

  The present inventors paid attention to the fact that phosphorus oxide (V) has sublimability and tried to form a film on the substrate by vapor deposition of phosphorus oxide (V) as a water absorption layer. As a result, phosphorus (V) oxide is heated and sublimated under reduced pressure, and deposited on the substrate by vapor deposition, so that the phosphorous (V) thin film is uniform, excellent in smoothness, and controlled within the preferred film thickness range. Was found to be formed into a film. An element similar to the above having this thin film as a water-absorbing layer is placed in an extremely low moisture environment of a ppb level or lower with a constant voltage of about several volts to 10 volts applied between the counter electrodes, and then ppb When the water concentration was increased to the level and ppm level, an increase in the interelectrode current corresponding to the increase in the water concentration was confirmed, and it was found that this was due to electrolysis of water molecules absorbed in the water absorption layer. Similarly, from a very low moisture environment below the ppb level, a trace amount of water is absorbed by the water absorption layer by exposing it to a moisture environment of a certain concentration above the ppb level for a certain period of time, and then returned to the environment below the ppb again to be constant. As a result of electrolysis of water with voltage, it was confirmed that the amount of current decreased with time, and that the amount of electricity became a value according to the moisture concentration at the time of exposure and the exposure time.

By using the micro moisture detection method of the present invention that exhibits the above characteristics, it becomes possible to evaluate the sealing performance of sealing measures such as organic EL devices and electronic devices that need to be sealed against moisture. .
FIG. 2 shows an element configuration in the case where a sealing layer (210) is formed as a moisture barrier film or moisture-proof film that prevents moisture permeation on the trace moisture measuring element (200) of the present invention. As a method for forming a moisture barrier film or moisture proof film, (a) adhesion through an adhesive layer of the moisture barrier film or moisture proof film, (b) film formation of a moisture barrier resin or moisture proof resin, ( c) Physical vapor deposition of moisture barrier materials or moisture proof materials such as inorganic oxides. Examples of the moisture barrier film or moisture proof film to be adhered include a multilayer body of a polymer and silica. The trace moisture measuring element that has been sealed with such a sealing layer is placed in a constant temperature and humidity environment for a certain period of time, and then electrolyzes the water absorbed by the water absorption layer by applying a voltage between the counter electrodes. From the amount of electricity, it is determined how much water molecules have entered through the sealing layer in a certain time.

  FIG. 3 is an element configuration example in the case where the trace moisture measuring element of the present invention is laminated on the organic EL element (300) and the sealing performance is evaluated. On the upper electrode (330) of the organic EL element (300) composed of the lower electrode (310), the organic EL active layer (320), and the upper electrode (330), a thin film insulating layer (340) excellent in electrical insulation is provided. A very small amount of moisture measuring element (200) is formed by stacking the substrates. The sealing performance evaluation is performed in the same manner as described above by using the sealed trace amount moisture measuring element after forming the sealing layer (210) by the same method as illustrated in FIG. Can do.

Further, by using the trace moisture measuring element of the present invention, a sealing agent such as an epoxy resin is applied to the outer peripheral portion of the substrate, which is generally performed in a liquid crystal display, and the space surrounded by the sealing agent is a moisture barrier material. It is also possible to evaluate the sealing performance of the sealing method of capping with the sheet. Examples of the moisture barrier material sheet include a glass plate, a metal plate, a ceramic sheet, and a multilayer body of polymer and silica.
FIG. 4 shows a case where a sealing agent surrounding a water absorption layer is applied on the substrate of the trace moisture measuring element (200) of the present invention, and the space surrounded by the sealing agent is sealed with a glass plate (420). In this case, the sealant itself, the sealant and the substrate, or the moisture entering the cap glass interface can be evaluated.

  The above-described measurement of trace moisture and the evaluation method of sealing performance against moisture will be described more specifically by the following examples, but the present invention is not limited to these examples.

(Example 1)
Gold having a thickness of 50 nanometers was vacuum-deposited on a quartz substrate through a shadow mask to form 5 pairs of comb-shaped counter electrodes having a line width of 100 microns and a length of 2 millimeters at intervals of 40 microns. This electrode-attached substrate is put in a vacuum deposition apparatus installed in a glove box with a very low moisture concentration nitrogen atmosphere, and a thin film of phosphorous oxide (V) having a thickness of about 100 nanometers is placed on the electrode under a pressure of about 1 Pascal. An extremely small amount of moisture measuring element 1 was formed by heating vapor deposition. The formed thin film of phosphorus oxide (V) had a substantially uniform thickness and a smooth surface.

(Example 2)
After enclosing the trace moisture measuring element 1 produced in Example 1 in a glove box with a very low moisture concentration nitrogen atmosphere in a sealed container that can be connected from the outside with a voltage application-current measuring instrument, the glove box Carried out. From this state, the pressure in the sealed container was reduced by the exhaust device until the pressure in the sealed container became a constant value of less than 1 × 10 ⁻⁴ Pascal, and then a constant voltage of 5 volts was applied to the comb-shaped counter electrode. FIG. 5 shows a change in the current value of the trace moisture measuring element 1 when the exhaust capacity of the vacuum pump is adjusted and the pressure inside the container is increased stepwise. The moisture concentration in the sealed container space when it is assumed that all the minute pressures in the sealed container are due to the vapor pressure due to residual moisture is shown in parallel with the pressure axis of FIG. FIG. 6 is an enlarged view of the portion of elapsed time from 5 minutes to 35 minutes. As is apparent from FIGS. 5 and 6, when a voltage is applied between the counter electrodes, the trace moisture measuring element 1 causes a current flowing between the electrodes in response to an increase in the internal pressure of the container from 10 ⁻⁴ Pascals to 10 Pascals. The value rose. The cause of the micro pressure generated inside the container is generally considered to be the vapor pressure of water leaking from the connection between the container and the pump and the sample inlet / outlet, or adsorbed on the inner wall of the container. The internal moisture concentration can be estimated. From the correlation with the moisture concentration described in parallel with the pressure axis in FIG. 5 and FIG. 6, the water absorption amount of the water absorption layer of the trace amount moisture measuring element 1 also changes as the moisture concentration rises in the 1 ppb level, and the voltage is It was confirmed that the amount of water molecules electrolyzed by the applied electrode was reflected in the electric field current.

(Example 3)
The trace moisture measuring element 1 produced in Example 1 was sealed in a sealed container in the same manner as in Example 2, the inside of the container was evacuated to 1 × 10 ⁻⁴ Pascal or less, and the current value in that state Until the voltage converged to a substantially constant value, a voltage of 10 volts was continuously applied to the electrode for a long time, and the water absorbed by the water absorption layer was sufficiently electrolyzed for dehydration. Immediately after the voltage application was stopped, the internal pressure of the container was rapidly increased to 2 × 10 ⁻³ Pascal, and the device was exposed under the same pressure for 1 minute. After reducing the internal pressure of the vessel rapidly to 1 × 10 ⁻⁴ Pascal or less again, a voltage of 10 V was applied to the electrode and the time decay of the amount of current was measured. The same operation and measurement were performed by changing the exposure time under 2 × 10 ⁻³ Pascal pressure to 2 minutes, 5 minutes, 10 minutes, and 20 minutes, respectively. FIG. 7 shows the exposure time dependence of the time decay of the current value together with the case of no exposure under 2 × 10 ⁻³ Pascal. The amount of current increased with increasing exposure time, and it was confirmed that the moisture absorbed in the water-absorbing layer increased with the exposure time. Even when no exposure is performed, attenuation of the electric field current is observed because water absorption into the water absorption layer occurs even in an extremely low moisture environment of 1 × 10 ⁻⁴ Pascal or less. FIG. 8 shows the relationship between the charge amount obtained by integrating the electric field current over time and each measurement electrolysis time. Since the amount of charge compared at the same time increased according to the length of the exposure time, it was confirmed that the change in the amount of water absorption can be measured as the amount of charge required for electrolysis by the element configuration of the extremely minute moisture measuring element 1.

(Reference Example 1)
In the same manner as in Example 1, gold having a thickness of 50 nanometers was vacuum-deposited on a quartz substrate through a shadow mask to form 5 pairs of comb-shaped counter electrodes having a line width of 100 microns and a length of 2 millimeters at intervals of 40 microns. . The substrate with the electrode is put in a container installed in a glove box having a very low moisture concentration nitrogen atmosphere, phosphorus oxide (V) is heated and sublimated, a thin film of phosphorus oxide (V) is formed on the electrode, and the moisture detecting element 1 is formed. Produced. The formed thin film of phosphorous oxide (V) exhibited a property in which acicular crystals were accumulated, and the surface was also uneven with acicular protrusions standing up, and an accurate thickness could not be measured.

(Reference Example 2)
In the same manner as in Example 2, the moisture measuring element 1 produced in Reference Example 1 is placed in a glove box having an extremely low moisture concentration nitrogen atmosphere in a sealed container to which a voltage application-current measuring instrument can be connected from the outside. After sealing, it was taken out of the glove box. From this state, the pressure in the sealed container was reduced by the exhaust device until the pressure in the sealed container became a constant value of less than 1 × 10 ⁻⁴ Pascal, and then a constant voltage of 5 volts was applied to the comb-shaped counter electrode. FIG. 9 shows changes in the current value of the moisture measuring element 1 when the exhaust capacity of the vacuum pump is adjusted and the pressure inside the container is increased stepwise. Similarly to FIG. 5, the moisture concentration in the sealed container space when the minute pressure in the sealed container is assumed to be due to the vapor pressure due to the remaining water is shown in parallel with the pressure axis of FIG. Compared with the extremely small amount of moisture detection element 1 produced in Example 1 using a uniform and highly smooth thin film of phosphorus oxide (V) as the water absorption layer, the change in the container internal pressure corresponding to the ppb level in terms of moisture concentration is an output. No change in the current value was observed, and only an increase in the current value on the order of 10 × ⁻¹³ amperes was shown with respect to a change in moisture concentration above the ppm level. From this result, it was confirmed that the sensitivity to trace moisture was improved when phosphorus oxide (V) was vapor-deposited under reduced pressure and a water-absorbing layer was formed as a uniform and smooth film as in Example 1. did.

  The present invention is not limited to the above embodiments, and various design changes can be made according to the technical scope of the present invention.

  The trace amount moisture detection element of the present invention can be used for measurement of trace amount moisture in an environment or the like where an anaerobic object that dislikes humidity such as an EL element is placed. In addition, the trace moisture detecting element of the present invention can be used for measurement and evaluation of moisture-proof sealing performance of a sealing layer, a sealing layer, and the like that protects an anaerobic object such as an EL element from surrounding moisture.

DESCRIPTION OF SYMBOLS 110 Substrate 120 Counter electrode 130 Water absorption layer 200 Trace amount moisture measuring element 210 Sealing layer 300 Organic EL element 310 Lower electrode 320 Organic EL active layer 330 Upper electrode 340 Thin film insulating layer 410 Sealant 420 Glass plate

Claims (6)

  A trace moisture detecting element comprising a pair or a plurality of pairs of counter electrodes formed on a substrate and a water absorbing layer of a water absorbing material formed in contact with the counter electrode, wherein the water absorbing layer has a thickness of It is a deposited thin film of phosphorus oxide (V) of 10 to 100 nanometers, and is configured such that a voltage for electrolyzing a trace amount of water absorbed in the water absorption layer is applied between the counter electrodes. Features a trace moisture detector.   A trace moisture detector including a pair or a plurality of pairs of counter electrodes formed on a substrate and a water absorption layer of a water absorbing material formed in contact with the counter electrode, wherein the water absorption layer has a thickness of It is a deposited thin film of phosphorus oxide (V) of 10 to 100 nanometers. By absorbing trace amounts of water existing around the water absorption layer with the water absorption layer, it is electrolyzed by applying a voltage between the counter electrodes. An ultra-trace moisture detection device configured to detect and quantify trace-volume moisture.   A sealing layer made of a moisture-proof material covering the water absorption layer is formed on the trace moisture detector according to claim 1, and the trace moisture is detected and quantified by the trace moisture detector. A moisture-proof sealing performance evaluation method for evaluating the moisture-proof sealing performance of a stop layer.   A moisture-proof sealing layer that seals both the water-absorbing layer of the trace moisture detector according to claim 1 and an electronic device that requires moisture-proof sealing is formed, and trace moisture is detected by the trace moisture detector. The moisture-proof sealing performance evaluation method for evaluating the moisture-proof sealing performance of the moisture-proof sealing layer by quantifying.   A sealing agent surrounding the water absorbing layer is applied to the substrate of the trace moisture detecting element according to claim 1, and a space surrounded by the sealing agent is capped with a sheet of moisture barrier material to seal the water absorbing layer. A moisture-proof sealing performance evaluation method for evaluating the moisture-proof sealing performance of the sealant by detecting and quantifying trace amounts of moisture with the trace moisture detection element. The moisture-proof sealing performance evaluation method according to any one of claims 3 to 5, wherein a plurality of pairs of counter electrodes of the extremely small amount of moisture detecting element are used and a moisture-proof sealing performance distribution corresponding to the distribution of the counter electrodes is evaluated.