JPH02291952A - Corrosion monitoring device for metal and electric apparatus provided with said device - Google Patents

Abstract

PURPOSE:To make it possible to measure the corrosion of metallic material, especially a metal thin film in atmosphere, highly sensitively and highly accurately by setting the ratio L/P between the facing length L of electrodes and the gap P between the electrodes at 10<3> or more, and providing a means for detecting the impedance value between the electrodes. CONSTITUTION:A main body 1 of an electronic device is housed in a casing 2 having an air intake port 3 and an air discharge port 4. An electrode element 5 for detecting the corrosion of the constituent metal of the electronic device is provided in the casing 2. The electrode element 5 has a pair of electrodes 8 and 8' which are constituted of a metal having the same composition as that of a metal whose corrosion is monitored on an insulating layer. The ratio L/P between the facing length L of the electrodes 8 and 8' and the gap P between the electrodes is set at 10<3> or more. Two AC voltages at a high frequency and a low frequency are applied to the electrodes 8 and 8' from an AC-voltage applying device 6. The impedance value between the electrodes at each frequency is measured with an impedance measuring device 7. In this way, the resistance of a water film formed on the electrode element 5 and the corrosion speed of the metal under test on the electrode element 5 can be directly measured continuously.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a corrosion monitoring device for monitoring the corrosion of metal materials in the atmosphere, particularly the corrosion status of metals used in electronic devices, etc. Relating to a device comprising a device.

[Conventional technology]

BACKGROUND OF THE INVENTION Various metal materials are used for wiring and recording of monk names in electronic devices such as electronic computers, semiconductor devices, and magnetic recording devices, as well as air conditioning devices.

However, such devices are used in a variety of environments. In particular, when used in the atmosphere, atmospheric moisture, So,...
The metals used for wiring and electrodes are corroded by the action of corrosive gases such as H and S, or corrosive substances such as NaCQ, which causes accidents such as disconnections and control failures. .

In order to prevent equipment accidents caused by the corrosion of these metals, it is necessary to monitor the atmospheric corrosion of these metals.

For continuous monitoring of the atmospheric corrosion status of metal materials, the same metal plate (Japanese Patent Application Laid-Open No. 63-83659) or different metal plates [Corrosion Science
on Science), Volume 20, Nos. 853-872
(1980)] is laminated with an insulating plate interposed therebetween. In addition, metal film electrodes were placed opposite each other with an insulating layer of about 0.2 mm in between [Corrosion Prevention 187, No. 247~
250 pages or Journal of Electrochemical Society (J. of [Electrochem.
oc. ) Volume 20, pp. 1354-1358, (19
In 1988), there is the Kinbon Mei method.

The above-mentioned method is a method of measuring the corrosion resistance of an electrode formed of a test metal, or electrochemically measuring a corrosion current flowing between electrodes.

[Problem to be solved by the invention]

Corrosion of metals in the atmosphere occurs when moisture in the atmosphere is adsorbed on the surface of the metal scrap, forming a thin water film, and then SO, H, S
This is caused by the dissolution of corrosive species such as NaCQ and NaCQ.

However, the water film on the metal surface is extremely thin, with a thickness of 10 to 100 monolayers, and even if we try to construct an electrode to measure the electrical resistance to measure the corrosion rate, the electrical resistance is extremely large. , accurate measurements cannot be made.

As a means of lowering this resistance, devises have been made to deposit inert fine particles on the electrode (Japanese Unexamined Patent Publication No. 83659/1983) or to coat the electrode with an electrolytic coating in order to help the measurement electrode absorb water. ing.

However, with these methods, there are problems such as it is difficult to measure the corrosion rate of metals in natural conditions, and the measurement environment is limited to coastal areas. The purpose of the present invention is to measure corrosion of metal materials, especially thin metal films in the atmosphere, with high sensitivity and precision in any environment, and to prevent corrosion accidents in electronic and electrical equipment. An object of the present invention is to provide a corrosion monitoring device and a storage device equipped with the device.

[Means to solve the problem]

The present invention relates to a metal corrosion monitoring device, and its gist is as follows: (1) An electrode element having a pair of electrodes made of a metal having the same composition as the metal to be corroded on an insulating layer can be installed in a corrosion monitoring environment. The ratio L/P of the opposing length L of the electrodes to the electrode gap P is 1.
03 or more, and has means for detecting an impedance value between the electrodes. (2) A metal device characterized in that it has means for applying a microvoltage of an alternating current with a frequency of 1 kHz or more and an alternating current of less than 1 kHz between the electrodes, and has a means for detecting an impedance value between the electrodes at each frequency. A corrosion monitoring device and a device equipped with the corrosion monitoring device. A feature of the present invention is that the electrical resistance of the measuring electrodes is reduced as a means to improve the accuracy of measured values.
This is an electrode element in which the length of the opposing electrodes is sufficiently large compared to the electrode gap. The state of corrosion of metal can be monitored by separately determining the corrosion resistance value related to corrosion of the metal and the resistance value of only the water film from the resistance value between the electrodes of the electrode element. The electrical resistance Rw of the drainage film formed between a pair of electrodes provided on the insulating layer is determined by the length of the opposing part of the electrodes and the electrode gap P.
, the thickness of the water film D, and the specific resistance ρ of the water film, there is a relationship shown by equation (l).

Rw=ρP/D L...(1) p and D are values determined by the measurement environment, and ρ depends on the type and amount of electrolyte contained in the water film, but is generally 10
Indicates a value of 3 to 10@ΩQm.

On the other hand, D is a value determined by the humidity in the measurement atmosphere, and is generally 100 to 1 μm.

Therefore, in order to lower the electrical resistance Rw of the water film, L should be made as large as possible with respect to P.

In reality, the maximum limit value for accurately measuring the resistance Rw of a water film is about 10@Ω, so unless the L/P ratio is 103 or higher, the i! It cannot be determined.

In order to satisfy the above conditions, the conventional electrode gap P must be 0.
．． For those with a diameter of about 2 mm, the length of the opposing part of the electrode is 2
00mm or more is required.

However, if P is used that is about 1 to 10 μm, L can be sufficiently measured with a length of about 1 to 10 mm.

If the latter micro-wiring electrode is mounted on an insulating substrate, it will be several meters long.
It can be made into a chip of about m square, which is very advantageous when it is incorporated into electronic devices and the like.

In the above, Ril'I! between the electrodes. The resistance component affected by I involves the resistance Rtg of the water film and the resistance value Re caused by the corrosion reaction of the metal electrode.

The Re value is the corrosion rate of the metal electrode, I corr, and (II)
(However, K is a constant determined by the type of metal.)

I corr=K/Re−
(II) Therefore, the corrosion rate I corr can be calculated if the corrosion resistance Re value is known.

? The AC impedance method is most suitable as a method for accurately determining the Rc value.

In this method, a high-frequency minute AC voltage and a low-frequency minute AC voltage are applied between a pair of electrodes, and the impedance at each frequency is measured.

According to this, the impedance Z measured at low frequency
, is shown by equation (m), whereas Z . ．． = 2R
c+Rw-(m) The impedance value Z}l measured at high frequency is the value expressed by equation (IV), that is, the electrical resistance value of the water film.

Zya=Rw...(IV)
The Rc value can be determined using equation (V) derived from equations (m) and (IV).

R c= (Z r. Z l{)/2
"■ (V) By the way, the frequency of the applied minute alternating current voltage varies depending on the capacitance component between the electrodes, so the impedance value in the range of 1 Hz to 1 kHz changes depending on the capacitance component between the electrodes. Frequencies of 1 kHz or higher are suitable.

The applied voltage value should be as low as possible in consideration of the influence of voltage application on the corrosion reaction, and is preferably 50 mV or less.

Note that the voltages of the two frequencies may be applied in a superimposed manner.

A corrosion monitoring device consisting of an electrode element, an AC voltage application device, and an impedance measurement device under the conditions detailed above can be used to measure the corrosion rate of metals in various environments with high accuracy.
Can be measured with high sensitivity.

In particular, electrode elements formed with fine electrodes are suitable as elements for detecting corrosion conditions in various electronic devices and electrical equipment.

In addition, using an electrode element in which one of the electrodes of the electrode element is made of a test gold film and the other is a sample electrode, and a metal/compound electrode film exhibiting a reversible potential such as Ag/AgCQ is formed, It is also possible to measure the corrosion potential of the test metal and determine the corrosion rate from the relationship between corrosion potential and corrosion rate determined in advance.

Furthermore, by combining an electrode element with a test metal film and a reference electrode film, a potential measuring device, and an arithmetic device that stores relational data between potential and corrosion rate and can calculate the corrosion rate from the corrosion potential, advanced corrosion detection can be achieved. You can get monitoring equipment. Similarly, using an electrode element in which one electrode is formed of a solid film sensitive to corrosive ions such as So4=, H+, CQ, etc., and the other is formed of a reference electrode film, the reference electrode and the solid film are used. The concentration of corrosive ions is determined from the potential difference with the electrode, and the corrosion rate of the target metal can be determined from the previously determined relationship between corrosive ion concentration and corrosion rate.

Electrode element with a corrosive ion-sensitive membrane and a reference electrode membrane,
An advanced corrosion monitoring device can be obtained by combining a potential measuring device and an arithmetic device capable of calculating corrosion rate from corrosive ion concentration-corrosion rate data.

A semiconductor device or a wiring board on which an electrode film is directly formed can be used not only as an electrode element of a corrosion monitoring device, but also as a device for directly monitoring its own corrosion status.

In electronic devices, electronic computers, electronic signal recording devices, outdoor electrical equipment, etc. equipped with the corrosion monitoring device, the corrosion status of the device itself can be constantly monitored, which is effective in managing the reliability of the device. It can also be incorporated into air conditioning control equipment to control indoor corrosive environments.

[Effect]

The reason why the corrosion monitoring device of the present invention has high measurement accuracy is that the length L of the facing portion of the electrodes of the electrode element is set to 1 with respect to the electrode gap P.
03 or more, and its resistivity is 103Ω or less. This is because when the resistance value becomes higher than this, the sensitivity deteriorates.

Furthermore, the main reason why the corrosion rate can be measured accurately under any environment is that the water film resistance Rw and the corrosion resistance Rc are measured separately.

[Embodiment 1] FIG. 1 is a configuration diagram showing an example of an electronic device equipped with a corrosion monitoring device of the present invention.

The electronic device main body 1 is housed in a casing 2 having an air intake port 3 and an air outlet 4, and a fan is provided inside the casing to supply outside air for cooling. An electrode element 5 is installed inside the casing 2 to detect corrosion of the constituent metals of the electronic device.

Two alternating current voltages, high frequency and low frequency, are applied to the electrodes of the electrode element 5 from an alternating current voltage applying device 6, and the impedance value between the electrodes at each frequency is determined by the impedance measuring device 7. It is now possible to directly and continuously measure the resistance of the drainage film formed on the electrode element and the corrosion rate of the test metal on the electrode element.

FIG. 2 shows a plan view of the electrode element 5 used in FIG. 1.

A pair of electrodes 8 and 8' of the metal film under test are formed in a comb-like shape on the insulating layer 1o of the substrate, and each electrode has a lead wire extraction pad 9 for connection to an external AC voltage applying device 6. , 9' are provided. FIG. 3 is a schematic partial cross-sectional view of the electrode element shown in FIG. 2. On the silicon substrate 11 which has been flattened, a layer of Si02 etc.
Afl wiring 1 with an electrode gap of 10 μm or less via WI10
2 is formed by patterning.

Next, using the AQ wiring 12 as a cathode, electrolytic plating is performed in a plating bath containing the same soluble salt as the constituent metal of the corrosion monitoring section of the electronic device to create an electrode element on which the test metal film 8 is formed.

By selecting the type of soluble salt, any type of metal can be formed on the electrode element.

FIG. 4 shows the corrosion rate when the electrode element 5 formed by electrolytic plating of Cu as a test gold film is left in an atmosphere of 95% RI-I at 40° C., and the same corrosion monitoring as in Example 1 is shown. It is a graph showing the results measured by the device.

When comparing the corrosion rate value in Figure 4 with the corrosion rate value determined by the cathodic reduction method of the thickness of the oxide film formed on the Cu plate in the same atmosphere, both values were within ±10%. There is only a difference of 81! by the corrosion monitoring device of the present invention! It was confirmed that the J constant value is highly accurate and sensitive. [Example 2] FIG. 5 is a schematic plan view of an electrode element for a corrosion monitoring device in which electrodes 8, 8' made of a test metal film are formed in a spiral shape.

Note that the shape of the electrodes of the electrode element is not particularly limited as long as the electrode gap and the length of the opposing electrodes have the above ratio.

[Example 3] FIG. 6 shows a sample metal film 8 and a reference electrode film 1 on the absolute R layer 10.
FIG. 3 is a sectional view of an electrode element formed with No. 3. It is possible to configure a corrosion monitoring device by combining the electrode element, a potential measuring device, and an arithmetic device that can calculate the corrosion rate from the relationship between potential and corrosion rate. [Example 4] FIG. 7 shows a reference electrode film 13 on an insulating layer 10 and an ion-sensitive JJ! FIG. 3 is a cross-sectional view of an electrode element on which J14 is formed.

A corrosion monitoring device can be constructed by combining the electrode element, a potential measuring device for the reference electrode membrane and the ion-sensitive membrane, and an arithmetic device capable of calculating the corrosion rate from the potential difference.

〔Effect of the invention〕

The corrosion monitoring device of the present invention has the excellent effect of being able to continuously measure minute corrosion rates of metal materials with high accuracy.

Further, by providing the corrosion monitoring device in an electronic device or the like, it is possible to prevent accidents caused by corrosion of the metal of the electronic device.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the configuration of an electronic device incorporating a corrosion monitoring device according to an embodiment of the present invention, FIGS. 2 and 5 are plan views of electrode elements of the corrosion monitoring device, and FIG. 3 is a diagram similar to that of FIG. FIG. 4 is a graph showing the corrosion rate of Cu at 45° C. and 95% RH. FIG. 6 is a partial cross-sectional schematic diagram of an electrode element equipped with an electrode for measuring corrosion potential. The figure is a schematic partial cross-sectional view of an electrode element equipped with an electrode for measuring corrosive ion concentration. 1... Electronic device body, 2... Casing, 3...
Air intake port, 5... Electrode element, 6... AC voltage application device, 7... Impedance selection device, 8, 8'.
...Electrode, 9,9'...Lead wire extraction pad, 10
... Substrate, 11... Insulating layer, 12... AQ wiring,
13... Reference electrode membrane, 14... Ion sensitive membrane. Figure 1 Figure 5 Figure 4 Figure 6 Figure 7 S9' 1... Electronic device body 2... Case 7/G 5... Electrode element 6... AC voltage application device 7... Impedance Measuring device 8, 8'... Electrode 10... Substrate 11... Insulating layer 12... A7 wiring 9, 9'... Lead wire extraction pad 10 Substrate 13... Reference electrode film 14...・・Io/sensitive membrane

Claims (1)

[Scope of Claims] 1. An electrode element having a pair of electrodes made of a metal having the same composition as a metal to be monitored for corrosion on an insulating layer is configured to be installed in a corrosion monitoring environment, The ratio L/P of the opposing length L and the electrode gap P is 1
0^3 or more, and comprising means for detecting an impedance value between the electrodes. 2. An electrode element having a pair of electrodes made of a metal having the same composition as the metal to be monitored for corrosion on an insulating layer is configured so that it can be installed in a corrosion monitoring environment, and the opposing length L of the electrodes; The ratio L/P to the electrode gap P is 1
0^3 or more, and an alternating current with a frequency of 1 kHz or more and a frequency of 1 Hz are applied between the electrodes.
What is claimed is: 1. A metal corrosion monitoring device comprising: means for applying the following minute alternating voltage; and means for detecting impedance values between electrodes at each frequency. 3. An electrode element in which a test metal electrode made of a metal with the same composition as the metal to be monitored and a reference electrode that exhibits a reversible potential in a corrosive environment are provided facing each other on an insulating layer is placed in a corrosion monitoring environment. It is configured so that it can be installed in the electrode, and the ratio L/P of the opposing length L of the electrodes to the electrode gap P is 1.
0^3 or more, and comprising means for detecting the corrosion potential of the test metal electrode with respect to the reference electrode. 4. An electrode element in which a test metal electrode made of a metal with the same composition as the metal to be monitored and a reference electrode that exhibits a reversible potential in a corrosive environment are provided facing each other on an insulating layer is placed in a corrosion monitoring environment. It is configured so that it can be installed in the electrode, and the ratio L/P of the opposing length L of the electrodes to the electrode gap P is 1.
0^3 or more, and includes means for detecting the corrosion potential of the test metal electrode with respect to the reference electrode, and means for calculating the corrosion rate of the test metal from the corrosion potential-corrosion rate relationship and the corrosion potential. A metal corrosion monitoring device characterized by: 5. An electrode element in which a solid membrane electrode that is sensitive to corrosive ions and a reference electrode that exhibits a reversible potential in a corrosive environment are provided facing each other on an insulating layer is configured so that it can be installed in a corrosion monitoring environment. , the ratio L/P of the opposing length L of the electrodes to the electrode gap P is 1
0^3 or more, and includes means for detecting the potential difference between the solid membrane electrode and the reference electrode, and means for calculating the corrosion rate of the test metal from the relationship between the corrosive ion concentration and the corrosion rate and the potential difference. A metal corrosion monitoring device comprising: 6. An electrode element in which a solid membrane electrode sensitive to corrosive ions and a reference electrode exhibiting a reversible potential in a corrosive environment are provided facing each other on an insulating layer is configured so that it can be installed in a corrosion monitoring environment. , the ratio L/P of the opposing length L of the electrodes to the electrode gap P is 1
0^3 or more, and has means for detecting the corrosive ion concentration from the potential difference between the solid membrane electrode and the reference electrode, and detects the corrosion rate from the relationship between the corrosive ion concentration and the corrosion rate and the corrosive ion concentration. A metal corrosion monitoring device characterized by having a calculation means. 7. Ratio L between the opposing length L of a pair of electrodes made of a metal with the same composition as the corrosion monitoring metal on the insulating layer and the electrode gap P
An electrode element having /P of 10^3 or more, and a means for applying a minute voltage of alternating current with a frequency of 1 kHz or more and alternating current of 1 Hz or less between the electrodes, and a test sample is obtained from the impedance value between the electrodes at each frequency. An electronic device comprising a metal corrosion monitoring device having means for calculating a metal corrosion rate. 8. Ratio L between the opposing length L of a pair of electrodes made of a metal with the same composition as the corrosion monitoring metal on the insulating layer and the electrode gap P
An electrode element having /P of 10^3 or more, and an AC voltage with a frequency of 1kHz or more and an AC voltage of 1H between the electrodes.
The present invention is characterized by comprising a metal corrosion monitoring device having means for applying a microvoltage of alternating current voltage of z or less, and having means for calculating the corrosion rate of the test metal from the impedance value between the electrodes at each frequency. Air conditioner. 9. A pair of electrodes, at least one of which is made of a metal having the same composition as the corrosion monitoring metal, are provided on the insulating layer, and the ratio L/P of the opposing length L of the electrodes to the electrode gap P is 10^ An electrode element for a metal corrosion monitoring device, characterized in that the electrode element has a corrosion resistance of 3 or more. 10. The ratio L/P of the opposing length L of a pair of electrodes on the insulating layer of the silicon chip, at least one of which is made of a metal with the same composition as the metal to be monitored for corrosion, and the electrode gap P is 10^
A semiconductor device comprising three or more electrodes.