JP2005214766A - Corrosion detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrosion detection device capable of detecting beforehand a failure of even an electrical apparatus using a printed circuit board to which a protection coating of a silicone-based resin is applied. <P>SOLUTION: This corrosion detection device is constituted of an insulating board, a test chip provided on the surface of the insulating board, and a detection part provided on the surface of the insulating board, for detecting an abnormality of the test chip. The test chip comprises an insulating plate, a thin line pattern provided on the surface of the insulating plate and formed by connecting in series a plurality of metals, and a silicone resin coating containing a humidifying agent for coating the surface provided with at least the thin line pattern of the test chip. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a corrosion detection apparatus for estimating the life of an electrical device used in a corrosive environment where heat and humidity are applied in a corrosive gas atmosphere.

  In general, industrial electrical equipment is often used for a long period of 10 years or longer in an installed environment. For this reason, it is designed and manufactured to have a sufficient product life, but when used in corrosive environments such as high temperature and high humidity, corrosive gas atmosphere, etc., conductive patterns on printed circuit boards, electronic components or contacts, etc. There is a risk that parts with relatively poor corrosion resistance will corrode in a short period of time and cause equipment failure.

Conventionally, it is difficult to predict the lifetime of electrical equipment with various installation environments. Therefore, measures such as replacement of a failed part or product after a product failure, that is, failure of a component constituting the product, have been taken. It was.
However, if parts and products can be exchanged before failure, it is preferable that the entire system can be prevented from being stopped due to failure of some devices.
Thus, as a device for diagnosing the environment in which an electrical device is installed, a device that exposes a wiring pattern on a printed circuit board to the atmosphere and detects corrosion damage of the wiring pattern by a change in conduction state is known.

  As a specific conventional corrosion detection device, on the printed circuit board, a wiring pattern detection portion made of copper foil exposed to the atmosphere is formed, and the corrosion of the copper foil portion causes the detection portion to break, When the electrical resistance value of the detection unit changes to a predetermined value or more, it is detected by the switching circuit connected to the detection unit, the display device is turned on, and the electrical device has begun to be affected by the failure in the environment of the installation location. There is a corrosion detection device that can be detected in advance (see, for example, Patent Document 1).

  As another conventional corrosion detection device, a conductive material for detection of various metal wirings made of copper, silver, iron, nickel, or an alloy thereof constituting a main part of an electric device provided in an insulating base block, and this detection There is a corrosion detection device including a detection unit made of a coating material having water absorption and gas permeability coated with a conductive material, a detection circuit for detecting an abnormality of the detection unit, and a display unit connected to the detection circuit ( For example, see Patent Document 2).

Japanese Patent Laid-Open No. 3-158748 (2nd page, FIG. 1) Japanese Patent Laid-Open No. 10-300699 (page 3, FIG. 1-2)

In the above-described corrosion detection device in which a wiring pattern detection unit made of a copper foil exposed to the atmosphere is formed on a printed circuit board described in Patent Document 1, other than the copper material used in the electrical equipment In addition to being able to diagnose damage to metal materials, there has been a problem that misdiagnosis occurs due to contact of a finger or adhesion of dust containing foreign matter.
Moreover, in the corrosion detection apparatus described in Patent Document 2, when a protective coating for dust prevention is applied to the wiring circuit of the printed circuit board, and a silicone resin coating is used as the protective coating, the corrosion detection apparatus There is a problem that there is a possibility that the abnormality detection and the failure of the printed circuit board may occur at the same time.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electrical device using a printed circuit board on which a protective coating of a silicone-based resin is applied, which can prevent misdiagnosis. Moreover, the corrosion detection apparatus which can detect the failure beforehand is obtained.

  The corrosion detection device of the present invention is a corrosion detection device for detecting corrosion of a printed circuit board coated with a silicone resin. The corrosion detection device includes an insulating substrate, a test chip provided on the surface of the insulating substrate, and the insulation. Provided on the surface of the conductive substrate and detecting the abnormality of the test chip, and the test chip is connected to the insulating plate and a plurality of metals provided on the surface of the insulating plate in series. And a coating film of a silicone resin containing a humidity control agent that covers at least the surface of the test chip provided with the fine line pattern.

  In the corrosion detection device of the present invention, the test chip is provided with an insulating plate, a thin wire pattern provided on the surface of the insulating plate, in which a plurality of metals are connected in series, and the surface of the test chip provided with the thin wire pattern. When an electric device having a printed circuit board coated with a silicone resin coating film is exposed to an atmosphere containing a corrosive gas. In this case, an abnormality can be detected without making a misdiagnosis before a failure due to corrosion of the printed circuit board occurs.

Embodiment 1.
1A and 1B are a plan view and a cross-sectional view, respectively, showing a corrosion detection apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, the corrosion detection apparatus 10 according to the present embodiment detects an abnormality of the insulating substrate 1 as a base, the test chip 2 provided on the surface of the insulating substrate 1, and the test chip 2 due to corrosion. The test chip 2 and the detection unit 3 are electrically connected by a copper wiring 4 formed on the surface of the insulating substrate 1. And the corrosion detection apparatus 10 is installed in the surface of the printed circuit board with which the coating film of the silicone resin which is protective coating was apply | coated, and the detection part 3 displays the abnormality detected by the detection part 3 (FIG. (Not shown).

FIG. 2 is a plan view (a) and a cross-sectional view (b) of the test chip 2 used in the present embodiment. The plan view of FIG. 2A shows a state in which a part of the fine line pattern 20 can be seen except for a part of the coating film 22 of the silicone resin containing the humidity adjusting agent provided on the outermost surface of the test chip 2. . As shown in FIG. 2, the test chip 2 of the present embodiment is connected to an insulating plate 21, a fine line pattern 20 provided on the surface of the insulating plate 21, and an end portion of the fine line pattern 20. The conductive portion 23 is connected to the front surface and the back surface, and the electrode pad 24 is connected to the conductive portion 23 and provided on the back surface of the insulating plate 21. The electrode pad 24 is joined to the copper wiring 4 with solder or conductive resin, and the test chip 2 is electrically connected to the copper wiring 4. The test chip 2 has at least a surface provided with the fine line pattern 20 covered with a silicone resin coating film 22 containing a humidity control agent.
FIG. 3 is a view showing a fine line pattern 20 provided on the surface of the test chip 2. The fine line pattern 20 provided on the test chip 2 is formed by connecting a plurality of metal wirings such as silver, aluminum, and copper used for wiring of a printed circuit board of an electric device and components to be mounted in series. That is, as shown in FIG. 3, the silver wiring 25 is formed between one conduction part 23 and the point c, the aluminum wiring 26 is formed between the point c and the point d, and the point d and the other conduction part 23 are connected. A copper wiring 27 is provided between them.

  The detection unit 3 is a switching circuit that detects a change in electrical resistance or disconnection of the test chip 2.

  Then, except for the test chip 2 parts, the same silicone resin coating as the protective coating of the printed circuit board is applied. When a coating film made of an acrylic resin, which is a resin having smaller water absorption and gas permeability than a silicone resin, is used as a coating film for coating other than the test chip 2 parts, a humidity control agent contained in the coating film 22 of the test chip. Can be prevented, which is more preferable.

  Next, the operation will be described. When the test chip 2 is disconnected due to oxidation or corrosion, or when the electrical resistance value of the test chip 2 increases to a predetermined value or more, this is detected by the detection unit 3 and a display device (not shown) is turned on. As a result, it is detected in advance that the electric device has started to be affected by the environment of the installation location, and a notification is given to the supervisor of the electric device.

In the corrosion detecting apparatus 10 of the present embodiment, the fine line pattern portion of the test chip 2 is coated with the same silicone resin coating film as the protective coating of the printed circuit board of the electrical equipment, and the metal of the fine line pattern 20 is the printed circuit board. It is exposed to the moisture absorption moisture environment and the permeation gas environment similar to the exposure of the metals, but the silicone resin coating film 22 provided on the surface of the fine line pattern 20 contains a refining agent, The metal corrosion of the fine line pattern 20 can be detected clearly.
Further, in the corrosion detection device 10 of the present embodiment, the thin line pattern 20 of the test chip 2 is formed by connecting a plurality of thin metal wires in series, and the increase in resistance due to corrosion of each metal is integrated, so that the test is performed. The characteristic change of the chip 2 is large, and the sensitivity of the test chip 2 is increased.

The insulating substrate 1 of the present embodiment is not particularly limited as long as it has insulating properties, copper wiring can be formed, and the test chip 2 and the detection unit 3 can be mounted.
The insulating plate 21 used for the test chip 2 can be a plastic plate, a glass plate, a ceramic plate, or the like, but using a substrate made of the same material as a printed circuit board used in a device that detects corrosion is used. This is preferable because the state of holding moisture absorbed and permeated gas is the same.

The metal of the wiring pattern 20 of the present embodiment may be an alloy of iron, nickel, silver, aluminum, copper, or nickel in addition to the above silver, aluminum, and copper.
And as a formation method of the wiring pattern 20, the film-forming method by said metal sputtering or vapor deposition is used. The width and thickness of the wiring pattern 20 are preferably the same as the narrowest width and the thinnest thickness in the wiring of the printed circuit board of the electrical device that detects an abnormality.

In this embodiment, examples of the humidity control agent include Na ₂ SO ₄ , CaSO ₄ , K ₂ SO ₄ , KNO ₃ , and Na ₂ CO ₃ , which are neutral salts with weak deliquescence. If the humidity control agent has a strong deliquescence property, the corrosion of the wiring pattern 20 of the test chip progresses too early, which is inappropriate. For example, NaOH generates a salt solution even in a normal environment without a corrosive gas, and the test chip wiring (particularly aluminum wiring) corrodes.
In the present embodiment, a saturated aqueous solution of a neutral salt with weak deliquescence such as Na ₂ SO ₄ , CaSO ₄ , K ₂ SO ₄ , KNO ₃ , and Na ₂ CO ₃ is prepared. A silicone resin coating film 22 provided on the surface is brought into contact with the silicone resin coating film 22 so that an aqueous solution containing a neutral salt is absorbed.

In the corrosion detection apparatus 10 according to the present embodiment, an electrical device including a printed circuit board to which a protective coating of a silicone resin is applied is sulfide gas (H ₂ S, SO ₂ ) that corrodes silver and sulfide that corrodes copper. Exposed to atmosphere containing gas (H ₂ S, SO ₂ ), ammonia, and chloride gas (HCl, Cl ₂ ) that corrodes aluminum, and make a misdiagnosis before failure of the printed circuit board due to corrosion Anomalies can be detected without incident.

Embodiment 2.
4A and 4B are a plan view and a cross-sectional view, respectively, showing a corrosion detection apparatus according to Embodiment 2 of the present invention. As shown in FIG. 4, the corrosion detection apparatus 10 according to the present embodiment includes a test chip 2 and a test chip 2 caused by corrosion on the surface of a printed circuit board 31 to which a coating film of a silicone resin as a protective coating is applied. A detection unit 3 for detecting an abnormality is directly installed. The configuration of the test chip 2 is the same as that of the first embodiment.
And the test chip 2 and the detection part 3 are electrically connected by the copper wiring 4 formed in the printed circuit board 31 surface.
Specifically, for example, the electrode pad of the test chip 2 provided with a silicone resin coating film containing a humidity control agent is bonded to the copper wiring 4 with a room temperature curable conductive resin.
In the corrosion detection apparatus 10 of the present embodiment, the test chip 2 and the detection unit 3 are directly provided on the printed circuit board 31. Therefore, the number of components is small, the mounting process is simple, and the productivity is excellent.

  Next, the present invention will be described in more detail with reference to examples.

Comparative Example 1
A thin wire pattern shown in FIG. 3 in which a glass epoxy substrate having a length of 12 mm, a width of 12 mm, and a thickness of 1 mm is used for the insulating plate 21, and a silver wiring 25, an aluminum wiring 26, and a copper wiring 27 are connected in series on this surface. 20 was formed by vapor deposition. For each metal, the thin wire portion has a length of 20 mm, a width of 0.1 mm, and a thickness of 0.02 mm. Each of the ends of the fine line pattern 20 was connected to the conduction part 23. A gold electrode pad 24 connected to the conductive portion 23 was provided on the surface opposite to the surface on which the fine line pattern 20 was provided. A silicone resin coating film was formed on the surface of the insulating plate 21 on which the fine line pattern 20 was provided, to produce a comparative test chip.

As an accelerated corrosion test, the comparative test chip was exposed to an environment having a temperature of 40 ° C., a relative humidity of 95%, and an H ₂ S gas concentration of 0.4 ppm, and an increase in electrical resistance and disconnection of the comparative test chip were evaluated. The obtained results are shown in Table 1 together with the corrosion test conditions.
As shown in Table 1, the period during which the electric resistance was doubled was 18 days, and the period during which disconnection occurred was 30 days.

Example 1.
In the same manner as in Comparative Example 1, a chip in which a silicone resin coating film was formed on the surface provided with the fine line pattern 20 was obtained. Furthermore, a 25 ° C. saturated aqueous solution of Na ₂ SO ₄ is prepared, the silicone resin coating film is brought into contact with this aqueous solution, and a silicone resin coating film 22 containing Na ₂ SO ₄ as a humidity control agent is provided. The same model test chip 2 as shown in FIG.

The model test chip 2 was subjected to the same accelerated corrosion test as in Comparative Example 1, and the increase in electrical resistance and disconnection of the model test chip 2 were observed. The obtained results are shown in Table 1 together with the humidity conditioner used and the corrosion test conditions.
As shown in Table 1, the period in which the electric resistance doubled was 15 days, and the period in which the disconnection occurred was 26 days, and the failure was detected earlier than the comparative test chip shown in Comparative Example 1.
That is, the corrosion detection apparatus using the test chip of this embodiment can detect in advance a failure of an electric device having a printed circuit board coated with a silicone resin.

Examples 2-5.
A model test chip 2 was produced in the same manner as in Example 1 except that the humidity control agents shown in Examples 2 to 5 in Table 1 were used.
The model test chip 2 was subjected to the same accelerated corrosion test as in Comparative Example 1, and the increase in electrical resistance and disconnection of the model test chip 2 were observed. The obtained results are shown in Table 1 together with the humidity conditioner used and the corrosion test conditions.
As shown in Table 1, the period in which the electrical resistance is doubled and the period in which the disconnection occurs are shorter than the comparative test chip shown in Comparative Example 1, that is, the failure due to corrosion was detected earlier.
That is, the corrosion detection apparatus using the test chip of any one of Examples 2 to 5 can detect in advance a failure of an electric device having a printed circuit board coated with a silicone resin.

Comparative Example 2.
A comparative test chip similar to Comparative Example 1 was used, and an accelerated corrosion test was conducted at a test condition of a temperature of 40 ° C., a relative humidity of 95%, and an SO ₂ gas concentration of 0.4 ppm. Observed. The obtained results are shown in Table 1 together with the corrosion test conditions.
As shown in Table 1, the period during which the electric resistance was doubled was 72 days, and the period during which disconnection occurred was 122 days.

Example 6
Using the same model test chip 2 as in Example 1, the same accelerated corrosion test as in Comparative Example 2 was performed, and an increase in electrical resistance and disconnection of the model test chip 2 were observed. The obtained results are shown in Table 1 together with the corrosion test conditions.
As shown in Table 1, the period in which the electrical resistance doubles is 58 days, and the period in which the disconnection occurs is 99 days, and the failure is detected earlier than the comparative test chip shown in Comparative Example 2 exposed to the same corrosive environment. did.
That is, the corrosion detection apparatus using the test chip of this embodiment can detect in advance a failure of an electric device having a printed circuit board coated with a silicone resin.

Comparative Example 3.
Using the same comparative test chip as in Comparative Example 1, the accelerated corrosion test was conducted with the test conditions of temperature 40 ° C, relative humidity 95%, Cl ₂ gas concentration 0.4ppm, and the electrical resistance of the comparative test chip was increased and disconnected. Observed. The obtained results are shown in Table 1 together with the corrosion test conditions.
As shown in Table 1, the period in which the electric resistance was doubled was 8 hours, and the period in which disconnection occurred was 12 hours.

Example 7
Using the same model test chip 2 as in Example 1, the same accelerated corrosion test as in Comparative Example 3 was performed, and an increase in electrical resistance and disconnection of the model test chip 2 were observed. The obtained results are shown in Table 1 together with the corrosion test conditions.
As shown in Table 1, the period in which the electrical resistance doubles is 5 hours, the period in which the disconnection occurs is 10 hours, and the failure is detected earlier than the comparative test chip shown in Comparative Example 3 exposed to the same corrosive environment. did.
That is, the corrosion detection apparatus using the test chip of this embodiment can detect in advance a failure of an electric device having a printed circuit board coated with a silicone resin.

Comparative Example 4.
A comparative test chip similar to Comparative Example 1 was used, and an accelerated corrosion test was conducted at a test condition of a temperature of 40 ° C., a relative humidity of 95%, and an NH ₃ gas concentration of 0.4 ppm. Observed. The obtained results are shown in Table 1 together with the corrosion test conditions.
As shown in Table 1, the period in which the electrical resistance was doubled was 4 days, and the period in which the disconnection occurred was 6 days.

Example 8 FIG.
Using the same model test chip 2 as in Example 1, the same accelerated corrosion test as in Comparative Example 4 was performed, and an increase in electrical resistance and disconnection of the model test chip 2 were observed. The obtained results are shown in Table 1 together with the corrosion test conditions.
As shown in Table 1, the period in which the electrical resistance doubles is 3 days, the period in which the disconnection occurs is 5 days, and the failure is detected earlier than the comparative test chip shown in Comparative Example 4 exposed to the same corrosive environment. did.
That is, the corrosion detection apparatus using the test chip of this embodiment can detect in advance a failure of an electric device having a printed circuit board coated with a silicone resin.

  The corrosion detection device of the present invention is a corrosion detection device that detects the corrosion of a printed circuit board coated with a silicone resin, and it is in advance that an electrical device has started to be affected by a failure in the environment of the installation site. It can be detected and the reliability of electrical equipment is improved by replacing parts and products before failure.

They are the top view (a) and sectional drawing (b) which show the corrosion detection apparatus of Embodiment 1. FIG. It is the top view (a) and sectional drawing (b) of a test chip used for the corrosion detection apparatus of Embodiment 1. It is a figure which shows the fine line pattern provided in the surface of the test chip. They are the top view (a) and sectional drawing (b) which show the corrosion detection apparatus of Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation board | substrate, 2 Test chip, 3 Detection part, 10 Corrosion detection apparatus, 20 Fine wire pattern, 21 Insulation board, 22 Silicone resin coating film containing a humidity control agent, 23 Conduction part, 24 Electrode pad.

Claims (3)

A corrosion detection device for detecting corrosion of a printed circuit board coated with silicone resin,
An insulating substrate, a test chip provided on the surface of the insulating substrate, a detection unit provided on the surface of the insulating substrate and detecting an abnormality of the test chip,
The test chip includes an insulating plate, a thin line pattern provided on the surface of the insulating plate, in which a plurality of metals are connected in series, and a humidity control agent that covers at least the surface of the test chip provided with the thin line pattern A corrosion detection apparatus comprising a coating film of a silicone resin containing A corrosion detection device for detecting corrosion of a printed circuit board coated with silicone resin,
A test chip provided on the surface of the printed circuit board, and a detection unit provided on the surface of the printed circuit board and detecting an abnormality of the test chip,
The test chip includes an insulating plate, a thin line pattern provided on the surface of the insulating plate, in which a plurality of metals are connected in series, and a humidity control agent that covers at least the surface of the test chip provided with the thin line pattern A corrosion detection apparatus comprising a coating film of a silicone resin containing The humectant is a neutral salt of at least one of Na ₂ SO ₄ , CaSO ₄ , K ₂ SO ₄ , KNO ₃ and Na ₂ CO ₃ , according to claim 1 or 2. Corrosion detector.

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