JP2012132718A - Corrosive gas resistance evaluation method and evaluation device of coating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corrosive gas resistance evaluation method of coating agent.SOLUTION: The corrosive gas resistance evaluation method has: a wiring forming process in which wiring is formed on a surface of an insulating substrate; a film forming process in which a coating film made of coating agent being an evaluation object is formed at least on a surface of the wiring; an exposure process in which the insulating substrate, on which the wiring and the coating film are formed, is exposed in atmosphere containing corrosive gas while electric resistance of the wiring is monitored; a film permeation time calculating process in which the time from the start of exposure to the time at which electric resistance begins to increase is obtained based on the monitoring result; a standard time calculating process in which the standard time being film permeation time per unit thickness is obtained based on the film permeation time and the thickness of the coating film; and an evaluating process in which corrosive gas resistance of the coating agent is evaluated by comparing the standard time with prescribed reference time or standard time obtained for other coating agent.

Description

  The present invention relates to a corrosive gas resistance evaluation method and an evaluation apparatus for a coating agent used for an electronic substrate of an electrical device.

  In electric equipment such as automobiles, aircraft, air-conditioning equipment, and industrial equipment, electronic boards on which mounting parts are mounted are used. In an electronic board on which a mounting component is mounted, copper or silver is used as a metal conductor, but there has been a report that copper or silver is sulfided by a sulfide gas (hydrogen sulfide, sulfur dioxide) (Patent Document 1, non-patent document). Reference 1).

  Therefore, it is known to apply a coating agent on the electronic substrate in order to prevent corrosion of the constituent metal of the electronic substrate from a corrosive gas typified by sulfurized gas. It is described that an acrylic resin is used.

  Here, as a method for examining the corrosive gas resistance of various coating agents, a metal plate on which a coating film is formed by applying a coating agent and drying is exposed to an atmosphere containing a corrosive gas for 10 days, A method for evaluating the corrosion state of a plate by appearance observation is disclosed (paragraph [0056] of Patent Document 1). However, since this method does not quantitatively evaluate the corrosive gas resistance, there is a large variation and it is difficult to perform an accurate evaluation. Further, when the coating agent or the coating film is not transparent, it is difficult to observe the corrosion state of the metal plate from the appearance.

  Patent Document 2 describes that a silicon substrate having a high hygroscopic property and gas permeability on a printed circuit board on which a corrosion detection conductive material is disposed is used as an environmental diagnostic device for electrical equipment. In this case, the corrosion-detecting conductive material is placed in a more highly corrosive environment as compared with the actual use state of the electric device by applying the silicon coating, and the corrosion is accelerated. Thereby, the damage of the metal used for an electric equipment can be detected and predicted in advance, and the failure by the corrosion of an electric equipment can be prevented beforehand.

  However, this diagnostic device is not intended to evaluate the corrosive gas resistance of the coating agent itself. In the diagnostic device described in Patent Document 2, the silicon coating does not cover the entire surface of the conductive material for corrosion detection, and the intrusion path for the corrosive gas to reach the surface of the conductive material passes through the coating film. It is clear that it is not used to evaluate the corrosive gas resistance of the coating agent itself because it exists in other than the route.

JP 2003-188503 A Japanese Patent Laid-Open No. 10-300699

Dr. Hiramoto, “Corrosion Acceleration Test of Electronic Components”, 33rd Technical Seminar Materials (Corrosion of Electronic Materials and Components and Countermeasures), Corrosion Protection Association, p.35, (2003)

  The present invention provides a method for evaluating the corrosive gas resistance of a coating agent, which can quantitatively evaluate the corrosive gas resistance of the coating agent itself and can be evaluated even when the coating agent or coating film is not transparent. The purpose is to do.

The present invention is a method for evaluating the corrosive gas resistance of a coating agent,
A wiring forming process for forming wiring on the surface of the insulating substrate;
A film forming step of forming a coating film made of a coating agent to be evaluated at least on the surface of the wiring; and
Exposing the insulating substrate on which the wiring and the coating film are formed to an atmosphere containing a corrosive gas while monitoring the electrical resistance of the wiring; and
Based on the result of the monitoring, the time from the start of the exposure until the electric resistance starts to increase is obtained, and the obtained time is required for the corrosive gas to penetrate the coating film and reach the surface of the wiring. Membrane permeation time calculation step, which considers the membrane permeation time as time,
A standard time calculation step for obtaining a standard time which is a membrane permeation time per unit thickness from the membrane permeation time and the thickness of the coating film;
Corrosive gas resistance of the coating agent, comprising: an evaluation step for evaluating the corrosive gas resistance of the coating agent by comparing the standard time with a predetermined reference time or a standard time obtained for another coating agent. It is an evaluation method.

Further, the present invention is a method for evaluating the corrosive gas resistance of a coating agent,
Forming at least two wirings having the same material and length on one surface of the insulating substrate at positions where the distance from the end of the insulating substrate is different from each other;
A film forming step of forming a coating film made of a coating agent to be evaluated at least on the surface of the wiring; and
Exposing the insulating substrate on which the wiring and the coating film are formed to an atmosphere containing a corrosive gas while monitoring the electrical resistance of each of the wiring;
Based on the result of the monitoring, the time from the start of the exposure until the electric resistance starts increasing is obtained for each of the wirings, and the difference between the shortest time and the other time among the obtained times is the shortest. The film permeation time is considered to be the film permeation time which is the time required for the corrosive gas to pass through the coating film and reach the surface of the wiring, provided that it is within 30% of the film. A time calculation step;
A standard time calculation step for obtaining a standard time which is a membrane permeation time per unit thickness from the membrane permeation time and the thickness of the coating film;
Corrosive gas resistance of the coating agent, comprising: an evaluation step for evaluating the corrosive gas resistance of the coating agent by comparing the standard time with a predetermined reference time or a standard time obtained for another coating agent. It is an evaluation method.

It is preferable that the wiring is made of a material that easily reacts with a corrosive gas.
The material that easily reacts with the corrosive gas is preferably copper or silver.

  The present invention also relates to a corrosive gas resistance evaluation of a coating agent, comprising an insulating substrate having wiring formed on the surface, a test tank controlled to an atmosphere containing corrosive gas, an electric resistance meter, and a data collector. Also related to the device.

  In the present invention, since the corrosive gas permeation time per unit thickness of the coating film can be calculated from the time when the electrical resistance of the wiring starts to increase and the thickness of the coating film, the corrosive gas resistance of the coating agent is quantitatively determined. Therefore, it is possible to accurately evaluate corrosive gas resistance. In addition, even when the coating agent or the coating film is not transparent, it is possible to evaluate the corrosive gas resistance of the coating agent.

  Further, in the present invention, when at least two wirings having the same material and length are formed on one surface of the insulating substrate at positions where the distance from the end of the insulating substrate is different from each other, Corrosive gas resistance of the coating film itself depends on whether the difference between the shortest time and the other time is within 30% of the shortest time until the electrical resistance obtained starts to increase. It is possible to judge whether or not can be correctly evaluated, and more accurate evaluation is possible.

It is a flowchart which shows the outline of the evaluation method of this invention. 4 is a schematic top view of an insulating substrate on which wiring used in the evaluation method of Embodiment 1 is formed. FIG. FIG. 6 is a schematic top view of an insulating substrate on which wiring used in the evaluation method of Embodiment 2 is formed. It is a schematic diagram which shows the outline of the evaluation apparatus of this invention. In Example 1, it is a graph which shows the electrical resistance change of the wiring which formed the coating film which consists of polyurethane resins. In Example 2, it is a graph which shows the electrical resistance change of the wiring which formed the coating film which consists of silicone resins.

  The present invention relates to corrosive gases of various coating agents by obtaining the time required for the corrosive gas to pass through the coating film made of the coating agent to be evaluated and reach the surface of the metal conductor or the like of the insulating substrate. A method and apparatus for assessing resistance. The coating film is formed on the surface on the wiring side of the test insulating substrate having the wiring formed on the surface.

  Here, the corrosive gas is a gas having a property of corroding a material (for example, a metal conductor such as copper or silver) used for wiring of various electronic boards. Specific examples include sulfur gas such as hydrogen sulfide and sulfur dioxide, chlorine gas, hydrogen chloride gas, hydrogen fluoride gas, ammonia gas, nitrogen dioxide gas, and ozone.

<Evaluation method>
FIG. 1 shows a flowchart relating to the evaluation method of the present invention. As shown in FIG. 1, the corrosive gas resistance evaluation method for a coating agent according to the present invention includes a wiring formation process, a film formation process, an exposure process, a film transmission time calculation process, a standard time calculation process, and an evaluation process. It is what has. The order of the steps does not necessarily need to be in this order, but preferably the steps are performed in this order. Other optional steps may be included as necessary. Details of each step will be described below.

(Wiring formation process)
In this step, wiring is formed on the surface of the insulating substrate.

  As a wiring material for forming the wiring, various known materials for wiring can be used, but it is preferable to use a material that easily reacts with corrosive gas. In the present invention, the time required for the corrosive gas to reach the back surface (the surface in contact with the wiring) from the surface of the coating film (the film transmission time) is defined as the time when the electrical resistance of the wiring starts to increase due to corrosion of the wiring. Therefore, by using a material that easily reacts with the corrosive gas as the wiring material, the corrosive gas that has permeated the coating film and reached the surface of the wiring can be detected at an early stage. As a result, the time lag between the time when the electrical resistance of the wiring starts to increase due to the corrosion of the wiring and the actual film permeation time of the corrosive gas is reduced, so that the corrosive gas resistance of the coating agent can be accurately and quantitatively evaluated. . Examples of wiring materials that easily react with corrosive gas include metal conductors that easily react with corrosive gas. Examples of the metal conductor that easily reacts with the corrosive gas include copper or silver.

  The wiring used in the present invention is preferably a thin film wiring. As the wiring becomes thicker, resistance changes are less likely to occur even if corrosion occurs on the surface of the wiring, and the time lag between the time when the electrical resistance of the wiring starts to increase and the actual permeation time of corrosive gas Therefore, it is difficult to make an accurate evaluation. In addition, when the wiring thickness is increased, for example, when a coating film is formed on the entire wiring side of the substrate to evaluate the resistance to corrosive gas, in the standard time calculation step, the film transmission time is simply calculated as the coating film thickness. It can no longer be obtained by dividing by (the length in the thickness direction from the surface of the insulating substrate to the surface of the coating film).

  The method for forming the wiring is not particularly limited, and various known methods for forming the wiring on the insulating substrate can be used. For example, there is a method in which a wiring material is formed by adhering to the surface of an insulating substrate using a sputtering method.

  The wiring is usually formed on one surface of the insulating substrate. Moreover, it is preferable that at least two wirings having the same material and length are formed on one surface of the insulating substrate at positions where the distance from the end of the insulating substrate is different from each other. This makes it possible to determine whether or not the corrosive gas resistance of the coating film itself can be evaluated in the membrane permeation time calculation step described later.

(Film formation process)
In this step, a coating film made of a coating agent to be evaluated is formed at least on the surface of the wiring.

  A coating agent is not specifically limited, What is necessary is just to select suitably the material used as the evaluation object by this invention. Usually, it is an electrically insulating material, and in various electronic boards that are used in a state exposed to corrosive gas, it satisfies the predetermined conditions suitable for protecting wiring etc. on the electronic board from corrosive gas. Material. Moreover, it is preferable that it consists of the material which can be apply | coated to an insulated substrate, and a silicone resin, a polyurethane resin, an epoxy resin etc. are mentioned as such a coating agent.

  The method for forming the coating film is not particularly limited, and various known methods for forming a coating film for protecting the wiring on the electronic substrate and the like can be used. Specifically, for example, a method of curing by applying a coating agent and then drying, a method of curing by electron beam irradiation, heat treatment or the like can be mentioned. Examples of the method for applying the coating agent include dip coating under a nitrogen atmosphere, flow coating using an automatic discharge machine, spraying, and brushing.

(Exposure process)
In this step, the insulating substrate on which the wiring and the coating film are formed is exposed to an atmosphere containing a corrosive gas while monitoring the electrical resistance of the wiring. When at least two wirings are formed on one surface of the insulating substrate, the exposure process is performed while monitoring the electrical resistance of each wiring.

(Membrane permeation time calculation process)
In this step, the time from the start of the exposure until the electric resistance starts to increase is obtained based on the result of the monitoring, and the corrosive gas reaches the surface of the wiring through the coating film for the obtained time. It is regarded as the membrane permeation time, which is the time required to do so.

Specifically, for example, the time from the start of exposure until the electrical resistance of the wiring material becomes twice the initial (pre-test) electrical resistance (ΔR / R ₀ defined by the following equation (1) is 1) can be the time from the start of exposure until the electrical resistance begins to increase.

ΔR / R ₀ = (R _T −R ₀ ) / R ₀ (1)
Here, R ₀ : electric resistance before the test, R _T : electric resistance after T time.

  Further, when at least two wirings are formed on one surface of the insulating substrate, the time from the start of exposure to the start of increase in electrical resistance is obtained for each of the wirings based on the result of the monitoring, On the condition that the difference between the shortest time and the other time is within 30% of the shortest time, the corrosive gas permeates the coating film through the shortest time and the surface of the wiring It is considered as the membrane permeation time, which is the time required to reach.

  Specifically, for example, a coating agent to be evaluated is applied over the entire surface of an insulating substrate on which two wirings are formed to form a coating film. At this time, the two wirings are arranged so that the distance from the end of the insulating substrate (the end of the coating film) to the wiring is different. The insulating substrate on which the coating film is formed is exposed to an atmosphere containing corrosive gas, and times T1 and T2 at which the electrical resistance of each wiring starts to change are obtained. If T1 and T2 are the same, it is judged that the corrosive gas resistance of the coating film itself has been evaluated, and this time is determined as the film permeation time (corrosive gas permeates through the coating film and reaches the surface of the wiring. Time).

  When T1 and T2 are different, it is considered that the corrosive gas is likely to permeate from the interface between the insulating substrate and the coating film. Therefore, from this time T1 and T2, the corrosive gas resistance of the coating film itself is obtained. It is judged that cannot be evaluated. In this case, it is necessary to consider evaluating again in an experimental system in which T1 and T2 are the same. Even if T1 and T2 are different, if the difference between T1 and T2 is within 30% of the shorter time of T1 and T2, it is considered substantially the same, and the shorter of T1 and T2 is shorter. Time can be regarded as the membrane permeation time. This is because the time T is expected to vary due to factors such as coating film thickness due to variations in the sample, so that it is considered that variations within 30% are variations between samples, and more than 30% are unacceptable variations.

(Standard time calculation process)
In this step, a standard time which is a membrane permeation time per unit thickness is obtained from the membrane permeation time and the thickness of the coating film. Thereby, influences such as the thickness of the coating film formed on the insulating substrate can be eliminated, and the corrosive gas resistance specific to the coating agent to be evaluated can be quantitatively evaluated.

(Evaluation process)
In this step, the corrosive gas resistance of the coating agent is evaluated by comparing the standard time with a predetermined reference time or a standard time obtained for another coating agent. Specifically, for example, a reference time is determined in advance by a preliminary experiment or the like, and when the standard time obtained by the above process is longer than the reference time, it is evaluated that the corrosive gas resistance is high, and is shorter than the reference time. In the case, it is evaluated that the corrosive gas resistance is low.

<Evaluation equipment>
The present invention relates to a corrosive gas resistance evaluation apparatus for a coating agent, comprising an insulating substrate having wiring formed on the surface, a test vessel controlled to an atmosphere containing corrosive gas, an electric resistance meter, and a data collector. Also related.

  As the insulating substrate, a substrate similar to the insulating substrate in which wiring is formed on the surface used in the above-described evaluation method of the present invention can be used. For example, an insulating substrate having such a wiring is exposed to an atmosphere containing a corrosive gas in a test tank after a coating film made of a coating agent to be evaluated is formed on the entire surface on the wiring side.

  The test tank has a function for making at least the inside thereof an atmosphere containing a corrosive gas. The test tank preferably further has a function capable of controlling the type and concentration of corrosive gas, temperature and humidity.

[Embodiment 1]
FIG. 2 shows a schematic top view of an insulating substrate on which wiring used in the evaluation method of the present embodiment is formed.

  As the insulating substrate 1, for example, a mounting circuit substrate such as glass, paper phenol, paper epoxy, or glass epoxy can be used. In order to prevent the wiring step of the thin film wiring material before the corrosive gas resistance evaluation test, the insulating substrate needs to have flatness, and the average surface roughness of the insulating substrate is desirably 1 μm or less.

  A first thin film wiring 21 and a second thin film wiring 22 are formed on the surface of the insulating substrate 1. The first thin film wiring 21 and the second thin film wiring 22 were formed by adhering the amount of wiring material to the surface of the insulating substrate 1 using a sputtering method. As the wiring material, a material similar to the material used for the wiring described above can be used.

  A coating agent having a thickness of 1 mm or less is applied to the surface of the first thin film wiring. In order to detect early when the corrosive gas reaches the back surface of the coating film, that is, the surface of the first thin film wiring, the electrical resistance of the first thin film wiring before the corrosive gas resistance evaluation test is several kΩ to several hundred kΩ. It is preferable that This is because when the thin film wiring resistance is 1 kΩ or less or 1 MΩ or more, it is difficult to detect an increase in resistance of the thin film wiring at an early stage. Therefore, it is preferable to set the material of the thin film wiring and the thickness, width, and length of the wiring so that the resistance of the thin film wiring is several kΩ to several hundred kΩ.

  The second thin film wiring 21 is installed in order to confirm that the corrosive gas permeates in the thickness direction of the coating film, and has the same wiring material, wiring thickness and width as the first thin film wiring.・ Set the length.

  The 1st thin film wiring soldering part 31 and the 2nd thin film wiring soldering part 32 are parts which solder a lead wire in order to measure the electrical resistance of a thin film wiring. The range of the 1st thin film wiring soldering part 31 and the 2nd thin film wiring soldering part 32 can be 10 mm long and 20 mm wide, for example.

  The distance L1 from the end of the insulating substrate to the first thin film wiring 21, the distance L2 from the end of the insulating substrate to the second thin film wiring 22, the first thin film wiring soldering part 31 or the second thin film wiring soldering from the end of the insulating substrate The distance L3 to the portion 32 is all 1 mm or more, and the thin film wiring is arranged so that L1 <L2 <L3.

  When the insulating substrate coated with this coating agent is exposed to a corrosive gas atmosphere, the corrosive gas permeates to the thin film wiring substrate through the film thickness direction of the coating agent and the interface between the coating agent and the insulating substrate. When the times T1 and T2 until the electric resistances of the first thin film wiring and the second thin film wiring start to increase are approximately the same value, it is considered that the corrosive gas permeates in the film thickness direction of the coating agent. T2 is regarded as the membrane permeation time and is used as an index of the corrosive gas resistance of the coating agent. Actually, it is difficult to make the film thickness of the coating agent and the electric resistance of each thin-film wiring completely the same, and there may be some variation, so the difference between T1 and T2 is smaller than the shorter time of T1 and T2. If it is within 30%, the corrosive gas is considered to have penetrated in the film thickness direction of the coating agent, and the shorter one of T1 and T2 is regarded as the membrane permeation time, and the corrosive gas resistance of the coating agent is considered. It can be used as an indicator. Here, “30%” is set in order to eliminate the influence of the sample variation and the gas intrusion from the interface between the insulating substrate and the wiring as described above. Further, the reason that the shorter time of T1 and T2 is regarded as the membrane permeation time is for performing a stricter (higher safety) evaluation, and is not limited to this, but other indices (for example, T1 and T2 The average value) can also be regarded as the membrane permeation time.

  Next, the time T (time / μm) per unit film thickness is obtained from the shorter time of T1 and T2 (T1 when T1 <T2) and the film thickness of the coating agent. This time T is a quantitative index for evaluating the corrosive gas resistance of the coating agent.

  On the other hand, if the difference between T1 and T2 is 30% or more of T1 and T2, it is considered that corrosive gas permeates from the interface between the coating agent and the insulating substrate. Therefore, since T1 and T2 are not evaluating the corrosive gas resistance of the coating agent itself, the data of T1 and T2 are not adopted.

[Embodiment 2]
FIG. 3 is a schematic top view of an insulating substrate on which wiring used in the evaluation method of the present embodiment is formed.

  In the insulating substrate shown in FIG. 3, the second thin film wiring 22 and the second thin film wiring soldering part 32 are installed so as to surround the first thin film wiring 21 and the first thin film wiring soldering part 31. Further, the distance L4 from the end of the insulating substrate to the first thin film wiring and the distance L5 from the end of the insulating substrate to the second thin film wiring are such that L4 and L5 are 1 mm or more and L5 <L4. Arrange the wiring. The insulating substrate of this embodiment is different from the insulating substrate shown in FIG. 2 used in the first embodiment in the arrangement of such thin film wirings, and other than that of the insulating substrate used in the first embodiment. It is the same.

  Even when an insulating substrate on which such wiring is formed is used, the corrosive gas resistance of the coating agent can be evaluated as in the first embodiment.

[Embodiment 3]
FIG. 4 is a schematic diagram showing an outline of a corrosive gas resistance evaluation apparatus for a coating agent according to the present embodiment.

  As the insulating substrate 41, the same substrate as the insulating substrate in which wiring is formed on the surface used in the above-described evaluation method of the present invention can be used. The insulating substrate 41 having such wiring is exposed to an atmosphere containing a corrosive gas in the test tank 42 after, for example, a coating film made of a coating agent to be evaluated is formed on the entire surface on the wiring side. The

  The test tank 42 has a function for making at least the inside thereof an atmosphere containing a corrosive gas. The test tank 42 preferably further has a function of controlling the type and concentration of corrosive gas, temperature, and humidity. In FIG. 4, a plug 43 is provided to maintain the atmosphere (temperature, humidity, corrosive gas) in the test tank 42.

  In order to measure the electric resistance of the wiring provided on the coated insulating substrate in the test tank 42, the wiring on the insulating substrate 41 and the electric resistance meter 45 are electrically connected by a lead wire 44. Various known electrical resistance meters can be used as the electrical resistance meter.

  A data collector 46 is also provided for collecting the measured electrical resistance values. Various known data collectors can be used as the data collector. For example, a constant flow flow type gas corrosion tester manufactured by Yamazaki Seiki Laboratory Co., Ltd. can be used.

Example 1
In this example, an insulating substrate in which wiring was formed in the arrangement shown in FIG. 2 used in the first embodiment was manufactured. A glass substrate was used as the insulating substrate 1, and the first thin film wiring 21 and the second thin film wiring 22 were formed by depositing copper on the surface of the insulating substrate 1 using a sputtering method. The dimensions of the first thin film wiring 21 and the second thin film wiring 22 were all 0.2 μm in thickness, 0.1 mm in width, and 10200 mm in length. Both the first thin film wiring 21 and the second thin film wiring 22 had an electric resistance of about 18 kΩ. Lead wires for measuring electrical resistance were soldered to the soldering portions 31 and 32 of the first thin film wiring 21 and the second thin film wiring 22.

Next, a polyurethane resin having a thickness of 5 μm was applied to the surface of the insulating substrate 1 on the thin film wiring side, and was cured by drying to form a coating film to be evaluated. The electrical resistance of the first thin film wiring 21 and the second thin film wiring 22 in a state where the insulating substrate 1 is exposed to an atmosphere having a temperature of 40 ° C., a relative humidity (RH) of 95%, and an H ₂ S concentration of 3 ppm. Was monitored. The measurement results are shown in FIG.

As shown in FIG. 5, the time T until the change in electrical resistance (ΔR / R ₀ defined by the above formula (1)) reaches 1 is substantially the same (45 hr) for the thin film wiring 1 and the thin film wiring 2. there were. Since the difference between the two times is within 30% of the shorter time, it is considered that the hydrogen sulfide gas resistance of the coating film itself made of silicone resin can be evaluated. Therefore, this 45 hr can be regarded as the time required for the corrosive gas (hydrogen sulfide gas) to permeate the coating film (film permeation time). Since the thickness of the coating film is 5 μm, the membrane permeation time (standard time) per unit thickness is 9 hr / μm. By comparing the obtained standard time with a predetermined reference time or the standard time obtained for other coating agents, the resistance of the silicone resin to corrosive gas (hydrogen sulfide gas) can be evaluated.

  In this embodiment, the insulating substrate 1 on which the first thin film wiring 21 and the second thin film wiring 22 are formed in the arrangement as shown in FIG. 2 is used. However, the first thin film wiring in the arrangement as shown in FIG. Even if the insulating substrate 1 on which the 21 and the second thin film wirings 22 are formed is used, the same result as described above can be obtained.

(Example 2)
In the same manner as in Example 1, an insulating substrate on which wiring was formed in the arrangement shown in FIG. 2 was produced, and lead wires were soldered.

Next, a 281 μm-thick silicone resin was applied to the surface of the insulating substrate 1 on the thin film wiring side, and was cured by drying to form a coating film to be evaluated. In the same manner as in Example 1, the insulating substrate 1 was exposed to an atmosphere having a temperature of 40 ° C., a relative humidity (RH) of 95%, and an H ₂ S concentration of 3 ppm. 2 The electrical resistance of the thin film wiring 22 was monitored. The measurement results are shown in FIG.

As shown in FIG. 6, the time T until the change in electrical resistance (ΔR / R ₀ defined by the above formula (1)) reaches 1 is approximately the same (237 hr) for the thin film wiring 1 and the thin film wiring 2. there were. Since the difference between the two times is within 30% of the shorter time, it is considered that the hydrogen sulfide gas resistance of the coating film itself made of silicone resin can be evaluated. Therefore, this 237 hr can be regarded as the time required for the corrosive gas (hydrogen sulfide gas) to permeate the coating film (film permeation time). Since the thickness of the coating film is 281 μm, the film permeation time (standard time) per unit thickness is 0.8 hr / μm. By comparing the obtained standard time with a predetermined reference time or the standard time obtained for other coating agents, the resistance of the silicone resin to corrosive gas (hydrogen sulfide gas) can be evaluated.

  In this embodiment, the insulating substrate 1 on which the first thin film wiring 21 and the second thin film wiring 22 are formed in the arrangement as shown in FIG. 2 is used. However, the first thin film wiring in the arrangement as shown in FIG. Even if the insulating substrate 1 on which the 21 and the second thin film wirings 22 are formed is used, the same result as described above can be obtained.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Insulation board | substrate, 21 1st thin film wiring, 22 2nd thin film wiring, 31 1st thin film wiring soldering part, 32 2nd thin film wiring soldering part, 41 Insulating board which apply | coated coating agent, 42 Test tank, 43 Plug, 44 lead wires, 45 electrical resistance meter, 46 data collector.

Claims (5)

A method for evaluating the corrosive gas resistance of a coating agent,
A wiring forming process for forming wiring on the surface of the insulating substrate;
A film forming step of forming a coating film made of a coating agent to be evaluated at least on the surface of the wiring; and
Exposing the insulating substrate on which the wiring and the coating film are formed to an atmosphere containing a corrosive gas while monitoring the electrical resistance of the wiring; and
Based on the result of the monitoring, the time from the start of the exposure until the electric resistance starts to increase is obtained, and the obtained time is required for the corrosive gas to penetrate the coating film and reach the surface of the wiring. Membrane permeation time calculation step, which considers the membrane permeation time as time,
A standard time calculation step for obtaining a standard time which is a membrane permeation time per unit thickness from the membrane permeation time and the thickness of the coating film;
Corrosive gas resistance of the coating agent, comprising: an evaluation step for evaluating the corrosive gas resistance of the coating agent by comparing the standard time with a predetermined reference time or a standard time obtained for another coating agent. Evaluation methods. A method for evaluating the corrosive gas resistance of a coating agent,
Forming at least two wirings having the same material and length on one surface of the insulating substrate at positions where the distance from the end of the insulating substrate is different from each other;
A film forming step of forming a coating film made of a coating agent to be evaluated at least on the surface of the wiring; and
Exposing the insulating substrate on which the wiring and the coating film are formed to an atmosphere containing a corrosive gas while monitoring the electrical resistance of each of the wiring;
Based on the result of the monitoring, the time from the start of the exposure until the electric resistance starts increasing is obtained for each of the wirings, and the difference between the shortest time and the other time among the obtained times is the shortest. The film permeation time is considered to be the film permeation time which is the time required for the corrosive gas to pass through the coating film and reach the surface of the wiring, provided that it is within 30% of the film. A time calculation step;
A standard time calculation step for obtaining a standard time which is a membrane permeation time per unit thickness from the membrane permeation time and the thickness of the coating film;
Corrosive gas resistance of the coating agent, comprising: an evaluation step for evaluating the corrosive gas resistance of the coating agent by comparing the standard time with a predetermined reference time or a standard time obtained for another coating agent. Evaluation methods.   The method for evaluating a corrosive gas resistance of a coating agent according to claim 1, wherein the wiring is made of a material that easily reacts with a corrosive gas.   The corrosive gas resistance evaluation method for a coating agent according to claim 3, wherein the material that easily reacts with the corrosive gas is copper or silver.   An apparatus for evaluating corrosive gas resistance of a coating agent, comprising an insulating substrate having wiring formed on a surface, a test chamber controlled to an atmosphere containing corrosive gas, an electric resistance meter, and a data collector.

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