JP2005074397A - Washing method of electronic equipment and its evaluating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a washing method of electronic equipment and its evaluating method by which regenerative washing of high reliability can be performed in a short time from washing to evaluation after washing according to an object to be washed of electronic equipment, a position thereof to be washed and soiling situations thereof. <P>SOLUTION: The washing method of the electronic equipment comprises a first washing process A2 in which the electronic equipment containing a soiled energized part is subjected to non-immersion washing with a first alcoholic aqueous solution of ≤60wt%, a second washing process A3 in which a residue of the first washing process is subjected to non-immersion washing with a second alcoholic aqueous solution of ≤60wt%, a purge process A4 for removing the residue after the second washing process and a drying process A5 for drying the electronic equipment after the purge process. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electronic device cleaning method and an evaluation method thereof, and more particularly, to an electronic circuit board or an electric circuit mounted on a control panel, a switchboard or the like that has been used for a long period of time in various field environments where the electronic device is installed. -It is related with the washing | cleaning method of electronic devices, such as an electronic component and a metal structure, and its evaluation method.

  Fouling substances such as dust and corrosive gas existing in the installation environment adhere to and accumulate on the surfaces of electronic components and metal structures of electronic devices equipped with electronic circuit boards used in the field. This fouling substance causes deterioration such as insulation deterioration, poor contact, and metal corrosion, and eventually causes a failure of electronic equipment.

  In general, such fouling substances are removed by vacuuming or wiping with a cloth soaked with alcohol.

  In addition, fires and the like may cause electronic equipment to be covered with soot, combustion gas, and fire extinguishing powder. In this case, fire extinguishing powder affected by soot, combustion gas, and heat easily absorbs pollutants that are harmful to electronic equipment, so to quickly restore an electronic equipment placed in such a state, It is necessary to remove the pollutant in a short time after the occurrence.

  However, such a highly hygroscopic fouling substance becomes a sticky fouling substance in a high humidity environment such as the rainy season, and therefore, it is difficult to suck with a vacuum cleaner, and it is often handled only by wiping and cleaning.

  In such a method for removing fouling substances, since fouling substances can be removed only within the reach of the hand or the nozzle of the vacuum cleaner, a considerable amount of fouling substances remain, so that a failure occurs after cleaning. Often occurs.

  As a method for cleaning an electronic circuit board or the like mounted on an electronic device, a cleaning method is performed in which the surface pollutant is removed by immersion in water. This immersion cleaning with water is effective in removing ionic contamination, which is a cause of insulation deterioration and corrosion, but water has a high surface tension, so it does not penetrate well into the details of mounted parts and also has a drying property. Since it was bad, drying for a long time was necessary after washing.

  In addition, organic solvent cleaning methods that have good penetration into the detailed structure of electronic equipment and excellent drying properties are limited in places where they can be cleaned because organic solvents are dangerous substances stipulated by the Fire Service Act. However, in the case of plastics and the like, there is a problem in work efficiency such as it is necessary to confirm in advance whether or not the constituent materials will be deteriorated before washing because it has the effect of swelling or dissolving with an organic solvent. It was.

  Therefore, the inventors have developed a cleaning method using an aqueous alcohol solution that has a high cleaning effect on ionic fouling substances that cause insulation deterioration and corrosion, and that does not damage the contaminated cleaning object due to cleaning. (For example, see Patent Document 1).

  However, this method has a problem that when an oily fouling substance is present, it takes a long time for cleaning because of insufficient cleaning power, resulting in a long time for drying.

  In addition, when the object to be cleaned is composed of precision parts such as an electronic circuit board, in order to remove the pollutant adhering to the surface, soak in the cleaning liquid for a long time so that the pollutant does not further penetrate, There is also a method of raising fouling substances.

  In this method, since a fouling substance may be dissolved and recontaminated in the immersion cleaning liquid, it is necessary to perform a masking process on all the parts that are liable to penetrate the immersion cleaning liquid. Therefore, there is a problem that workability is extremely lowered.

  Further, in the final step of the cleaning process of the pollutant adhered to the surface by the above method, for example, in the case of an electronic circuit board, the surface is coated to prevent the pollutant. However, in the case of a painted surface of a metal structure or the like, since there was no effective cleaning method having an effect of preventing re-fouling of the re-painted film, it was difficult to take measures for preventing fouling.

  Also, metal cooling parts of electronic devices that are easily affected by the atmosphere, such as aluminum cooling fins used in vehicles, are corroded by ionic pollutants such as sea salt particles and sulfurous acid gas in the environment of use. It's easy to do. This cleaning of the metal part is often a cleaning method in which fouling substances are dissolved and removed by jetting water.

  However, in such a cleaning method, water does not penetrate into the details of the structure of the electronic device having a complicated shape or gap, but rather, the water in which the dirt is dissolved accumulates in the gap, and the remaining high-concentration pollutant There was a problem of being corroded by.

In addition, as a method for evaluating the cleaning effect of electronic equipment, etc., the insulation resistance was measured by sticking a conductive tape for electrodes on the surface, and it was determined that the predetermined resistance value was restored. It is easily affected by temperature and humidity, and accurate determination is difficult with this method.
JP-A-9-71884

  As described above, conventional cleaning methods for electronic devices have been attempted for various types of cleaning depending on the cleaning target of the electronic device, the installation environment of the electronic device, the fouling substance, and the fouling state. An effective cleaning method has not been established that is systematized for the cause of the installed polluted environment and the damaged site.

  That is, if the fouling state of the electronic device is a fouling substance containing an ionic substance or oily substance, there is a risk of recontamination by ionic substance or oily substance dissolved in the washing liquid when immersion cleaning is performed. There is a problem that it is difficult to replace the cleaning liquid. In addition, there is a problem that workability is poor, such as masking required for parts that are likely to be infiltrated with cleaning liquid during cleaning.

  In addition, re-coating treatment may be applied to prevent re-fouling of the resin coating agent surface of electronic equipment and the coating surface of electronic equipment outer packaging, etc., but there is no effective cleaning method for preventing re-fouling of the re-coated film. It was.

  In addition, when ionic fouling substances adhere to metal structures having complicated shapes in electronic equipment, a high-concentration cleaning liquid remains in the gaps when the water jet fountain cleaning method is used, resulting in pit-like pitting corrosion. There is a problem that causes

  Furthermore, there is no satisfactory method for measuring the insulation resistance value indicating the degree of recovery of these electronic devices, and it has been difficult to determine the quality of the cleaning result.

  The present invention has been made to solve the above-mentioned problems, and the reliability from the cleaning to the evaluation after the cleaning is short and reliable depending on the cleaning object of the electronic device, the contaminated object to be cleaned and the contamination state thereof. It is an object of the present invention to provide a method for cleaning an electronic device and a method for evaluating the same, which can perform regenerative cleaning with high accuracy.

In claim 1, the electronic device including the contaminated current-carrying part is washed with a first alcohol aqueous solution of 60% by weight or less in the first alcohol aqueous solution, and the second alcohol aqueous solution of 60% by weight or less. A second cleaning step for non-immersing and cleaning the residue of the first cleaning step; and a purge step for removing the residue after the second cleaning step;
And a drying step of drying the electronic device after the purging step.

  According to the present invention, since the electronic circuit board of the electronic device and the electronic component on the board are non-immersed and washed with an alcohol aqueous solution of 60% by weight or less, a fouling substance that adheres over time in an atmospheric environment, that is, Efficient to remove pollutants in a short time due to dust particles adsorbed by corrosive gases such as sea salt particles, NOx and SOx in the atmosphere, which are ionic dusts that have a high potential to affect electrical characteristics Cleaning is possible.

  In addition, since this cleaning liquid does not damage various parts and materials of the electronic equipment, it is not necessary to perform masking or prior cleaning evaluation tests.

  According to a second aspect of the present invention, there is provided a first cleaning step for non-immersing and cleaning the electronic device including the contaminated energized portion with a 40 to 60 wt% first alcohol aqueous solution to which a surfactant is added, and the surfactant. A second cleaning step in which the residue of the first cleaning step is non-immersed and washed with an aqueous solution of 60% by weight or less of the second alcohol that is not included; a purge step of removing the residue after the second cleaning step; And a drying step of drying the electronic device after the purge step.

  According to the present invention, an electronic circuit board of an electronic device and an electronic component on the board are made into a 40 to 60% by weight alcohol aqueous solution having high solubility in both ionic and oily pollutants, Since surfactants are added to the product and non-immersed cleaning is performed, the fouling substances adhering to the electronic circuit boards of electronic devices and the electronic component surfaces on the boards that have been placed in a factory atmosphere containing oily smoke for a long period of time can be removed for a short time. Can be cleaned efficiently.

  In addition, since the non-immersion cleaning is performed with a 60% by weight alcohol aqueous solution that does not contain a surfactant, the ionic substance that causes corrosiveness is equivalent to the water cleaning and can be dried in a shorter time than the case of the water cleaning.

  According to the fourth aspect of the present invention, there is provided a first cleaning step in which a non-conducting portion of a soiled electronic device is non-immersed and cleaned with a 40% to 60% by weight first alcohol aqueous solution to which a surfactant is added; A second cleaning step in which the residue of the first cleaning step is non-immersed and cleaned with a 60% by weight or less second alcohol aqueous solution not containing an agent; and a purge step in which the residue after the second cleaning step is removed. After the purge step, the electronic device is dried after the drip-proofing step of spraying a third alcohol aqueous solution of 60% by weight or less to which an antistatic agent or a drip-proofing agent is added, and after the drip-proof finishing step. And a drying step.

  According to the present invention, a drip-proof finish is performed by spraying a 60% by weight or less alcohol aqueous solution to which an antistatic agent or a drip-proofing agent is added, on a structure in which a non-contamination treatment cannot be performed on a non-conducting portion of an electronic device. Therefore, the reattachment of the fouling substance can be suppressed.

  According to claim 5, the surfactant is a mixture of a nonionic surfactant and an anionic surfactant, and the addition amount is 0.1 to 0.3% by weight of the first aqueous alcohol solution. It is characterized by that.

  According to the present invention, since a small amount of a nonionic or anionic mixture of surfactants with less foaming and good foaming is added, the oily fouling substance can be efficiently washed in a short time.

  According to claim 6, the antistatic agent or drip-proofing agent is an anionic (anionic) surfactant, a cationic (cationic) surfactant or a nonionic (nonionic) surfactant, And any one of these admixtures.

  According to the present invention, since the surfactant is selected depending on the target material to be cleaned, it is possible to suppress the reattachment of dirt.

  According to the seventh aspect of the present invention, the first hot water cleaning step of non-immersing and cleaning the metal part of the damaged electronic device with hot water of 60 ° C. or higher, and non-immersing with an aqueous solution of 30% by weight or more of alcohol added with a corrosion inhibitor. And a second anticorrosive finish cleaning step for cleaning.

  According to the present invention, since the metal portion of the electronic device is non-immersed and washed with hot water of 60 ° C. or higher, the solubility of the corrosive factor attached to the metal surface is increased. Furthermore, since non-immersed finish cleaning is performed with an alcohol aqueous solution of 30% by weight or more to which a corrosion inhibitor suitable for the type of metal is added, anticorrosion properties can be imparted and drying time can be shortened.

  According to claim 10, the equivalent salt content and the surface insulation resistance of the insulation part to be measured are measured in advance, and the correlation between the equivalent salt content and the surface insulation resistance is stored as a database, and the measurement object The equivalent salinity amount of the target surface is measured, and the measurement result is compared with the database to determine whether or not the target surface has recovered within a predetermined range of surface insulation resistance.

  According to the present invention, it is possible to estimate the insulation resistance value in consideration of the removal rate of fouling substances and the measurement environmental conditions from the measurement of the equivalent salt content on the surface to be cleaned. Can be judged.

  As described above, according to the present invention, it is possible to select an optimal cleaning method that can be recovered in a short time depending on the location and state of contamination of the electronic device, and quantitatively determine the quality of the cleaning result. Therefore, it is possible to provide a highly reliable electronic device cleaning method and its evaluation method.

  The best modes of the first to fifth embodiments will be described with respect to four representative models showing the fouling state of an electronic device.

  Example 1 is cleaning of electronic equipment that has been placed in an environment exposed to the atmosphere such as dust and exhaust gas for a long period of time, Example 2 is electronic equipment used in a factory with a lot of oily smoke, and combustion gas and digested powder due to fire Cleaning the electronic equipment when it is soiled by the air, Example 3 is a case of roadside lighting equipment, etc., such as the outer box of electronic equipment that has been placed in an atmospheric environment that is exposed to car exhaust gas or sea salt particles in the coastal zone for a long time. The cleaning of the painted surface and the fourth embodiment will explain the best mode for cleaning the metal structure of the electronic device mounted on the vehicle or the like placed in the traveling environment on the rail.

  In addition, a cleaning evaluation method using an insulation resistance value measuring method will be described in Example 5.

  An electronic circuit board of an electronic device including a current-carrying portion and an electronic component on the board have been used for a long period of time in an atmospheric environment containing ionic dust particles adsorbed with corrosive gas such as sea salt particles, NOx, SOx, etc. In some cases, the deterioration of electronic equipment progresses over time due to the adhesion of these dust particles.

  FIG. 1 is a flowchart showing a cleaning process of an electronic circuit board used in such a polluted atmospheric environment. Hereinafter, this embodiment will be described with reference to FIG.

  The cleaning process is a dust cleaning process A1 for removing dust as a pre-cleaning operation, a pre-cleaning process in which a cleaning liquid is sprayed on the substrate surface until the dust is in a state where it cannot be visually observed, and dust particles are mainly cleaned without being immersed. The process includes a process A2, a final cleaning process A3 for mainly removing ionic fouling substances, a purge process A4 for blowing off the cleaning liquid, and a drying process A5 after the purge.

  Next, the cleaning method in each step will be described with reference to FIG. First, when the amount of dust on the surface of the electronic circuit board 1a is large, the dust on the surface is sucked and removed by brushing with a soft brush 1b with a suction device such as the vacuum cleaner 1c in the dust removing step A1. When there is little dust, the dust removal step A1 can be omitted.

  Next, in the preliminary cleaning step A2, the substrate rack 2d is placed in the antistatic container 2c, and the electronic circuit board 1a is set thereon. At this time, as the cleaning liquid, an alcohol aqueous solution composed of 57% by weight of distilled water or ion-exchanged water, 41% by weight of ethyl alcohol and 2% by weight of isopropyl alcohol is put in the sprayer 2e, and the cleaning liquid is applied to the surface of the electronic circuit board 1a by the sprayer 2e. Spray.

  If the pollutant cannot be removed simply by spraying, light brushing with the soft brush 1b and spraying of the cleaning liquid are alternately repeated, and non-immersion cleaning is performed until dust particles can be removed. The quality of this cleaning is judged visually.

  The alcohol concentration of this aqueous alcohol solution is in the range of 40 to 60% by weight, which is highly soluble in both ionic substances and oily substances, and the alcohol is infinitely compatible with water and has an aliphatic content of 4 or more carbon atoms. A combination of alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol is used.

  The selection of the concentration of the aqueous alcohol solution and its cleaning effect have already been disclosed by the present inventors in JP-A-7-71884.

  Next, in the final cleaning step A3, the main purpose is to remove the ionic fouling substances after the dust particles are removed in A2 in the preliminary cleaning step. Therefore, the aqueous solution of 60 wt% or less used in the preliminary cleaning step A2 or An alcohol aqueous solution having a lower concentration, for example, 40% by weight or less, is placed in the sprayer 2e, sprayed onto the surface of the electronic circuit board 1a, and washed without immersion.

  In this way, by changing the alcohol concentration of the cleaning liquid between the preliminary cleaning step A2 and the final cleaning step A3, the amount of alcohol used is suppressed, and a more economical cleaning effect becomes possible.

  This cleaning is also performed by placing the substrate rack 2d in the antistatic container 2c so that the electronic circuit board 1a touches the cleaning liquid accumulated on the bottom of the antistatic container 2c and does not re-contamination.

  In addition, a relay, a transformer, a volume resistor and the like that may allow the cleaning liquid to enter the inside are attached to the surface on the electronic circuit board 1a. However, the electrical characteristics of these parts change before and after cleaning in advance. It is verified that the invading cleaning liquid evaporates and does not contaminate the inside.

  These electronic components were immersed in a cleaning solution at 40 ° C. for 30 minutes, and the electrical characteristics before and after the comparison were verified. As a result, they could be reused without any difference. It was confirmed.

  Next, after the finish cleaning step A3 is completed, clean air or nitrogen gas is sprayed and adhered to the surface of the electronic circuit board 1a immediately using the air gun 4g connected to the nitrogen gas or compressed air cylinder in the purge step A4. Blow away the cleaning solution. By this purging step A4, it is possible to blow away the cleaning liquid that has entered under the electronic components mounted on the electronic circuit board 1a or inside the connector.

  Next, after the purge process A4, the cleaned electronic circuit board 1a is quickly dried in the drying furnace 5h set at 60 ° C. for 2 hours in the drying process A5. Since the electronic circuit board 1a has been used for a long period of time, the drying temperature is, for example, a maximum of 60 ° C. within the storage temperature range of the electronic component.

  The basis for setting the drying time to 2 hours will be described with reference to FIG. The electronic circuit board 1a once cleans and dries the board mounted with high density, and measures the weight of the electronic circuit board 1a and the insulation resistance of the substrate surface.

  FIG. 2 shows the changes over time in the substrate weight and the insulation resistance between the electrodes in the drying process, in which the substrate weight and the insulation resistance value are set as initial values in the drying process after the nitrogen gas purge and the drying temperature is set to 60 ° C. The results of the investigation are shown.

As shown in the figure, the weight of the substrate returns to the weight before the cleaning in a drying time of 15 minutes, and at this time, the cleaning liquid on the surface of the substrate is almost evaporated. On the other hand, as indicated by the broken line, the insulation resistance value recovers to a predetermined value (10 ¹² = 1.E ⁺¹² Ω) or more after 110 minutes, so that it is assumed that power is supplied in a short time after cleaning. The drying time was set to 2 hours.

  This drying time can be shortened by spraying ethyl alcohol onto the surface of the electronic circuit board 1a after the purge step A4 and replacing the cleaning liquid on the substrate surface with alcohol. Further, if the drying furnace 5g is decompressed to accelerate the evaporation of the cleaning liquid that has penetrated into the drying furnace, the time is further shortened.

FIG. 3 shows the measurement results of the equivalent salinity before and after cleaning of the three types of electronic circuit boards 1a (board 1 to board 3) having different fouling levels cleaned in such a process. As shown in FIG. 3, even if the level of fouling before cleaning is different, the equivalent salt content after cleaning is reduced to 0.01 mg / cm ² or less, and the cleaned electronic circuit board 1a has a predetermined insulation resistance. The value recovered to 10 ¹² Ω (= 1.E ⁺¹² ) or more. As a result, it was judged that it could be reused, and the effect of this cleaning method was confirmed.

  The method for determining the quality of the cleaning result based on the correlation between the equivalent salt content and the insulation resistance is an evaluation method common to the respective examples, and will be described in detail in Example 5.

  Although the said Example demonstrated the example of the electronic circuit board 1a, it is applicable also when wash | cleaning the whole unit which accommodated the board | substrate other than that. Cleaning and disassembling electronic equipment has a higher cleaning effect. However, if a short recovery time is required and disassembly is not possible, the cleaning effect can be obtained even if the entire electronic device is washed based on the cleaning process of this embodiment.

  Electronic circuit boards of electronic equipment and electronic parts on the boards are installed for a long time in an environment that touches the atmosphere of a factory containing oily smoke using machine oil, etc., or the atmosphere containing oil mist in a steel mill rolling mill. May be. The electronic circuit board of such an electronic device and the electronic components on the board are accumulated with a fouling substance containing these oil components, and the deterioration progresses over time.

  In addition, fires may occur rarely in factories with a large amount of oil components, and it is possible to quickly restore electronic circuit boards that have been contaminated by digestion powder and cables such as cables accompanying digestion activities. Sometimes you want to.

  The second embodiment is a cleaning method in the case where an electronic circuit board of an electronic device placed in such an environment and electronic components on the board are regenerated and restored in a short time, and will be described with reference to FIG.

  The difference between Example 2 and Example 1 is that, in the pre-cleaning step A2, in order to remove the oil component that is the main fouling substance, cleaning is performed by spraying a cleaning liquid to which a surfactant is added. Other steps are the same as the cleaning step described in the first embodiment, and thus the description thereof is omitted.

  In the preliminary cleaning step A2 in Example 2, a cleaning liquid to which a small amount of a surfactant is added is used. This surfactant includes, for example, a polyoxyethylene alkyl ether represented by the following (Chemical Formula 1), which is a nonionic surfactant with good foam removal, and an anionic surfactant with excellent dispersibility. There is a certain sodium alkyl ether sulfate ester shown in the following (Chemical Formula 2).

RO— (CH ₂ CH ₂ O) _n —OH (1)
Here, R represents an alkyl group or an alkylphenyl group,
RO-SO ₃ Na (chemical formula 2)
Here, R represents an alkyl group.

  The concentration of the surfactant to be added may be increased up to 3% by weight with respect to the aqueous alcohol solution, depending on the amount of oily fouling substance and detergency. If the added amount is too much, foaming occurs too much, and the surfactant remains even after the final cleaning step A3, and cleaning takes time.

  That is, the recommended cleaning liquid has high solubility of oily substances and high solubility of ionic substances, for example, a mixture of 57% by weight of distilled water or ion-exchanged water, 41% by weight of ethyl alcohol, and 2% by weight of isopropyl alcohol. A solution obtained by adding 0.1 to 0.3% by weight of the above-described surfactant to the liquid is sprayed into the sprayer 2e until the darkening due to dust particles and oil components on the surface of the electronic circuit board 1a is not visible by visual observation. Repeat the non-immersion cleaning.

  In addition, the alcohol concentration of the aqueous alcohol solution in this case is almost the same as long as it is in the range of 40 to 60% by weight in order to ensure the solubility of the oily substance, as described above.

  The alcohol may be an alcohol having 4 or more carbon atoms that is infinitely compatible with water, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and the like.

  Next, in the final cleaning step A3, the residual surfactant is added to the sprayer 2e with an alcohol aqueous solution of 60% by weight or less that is also effective for dissolving the same ionic substance as in Example 1 in which no surfactant is added. The substrate is sprayed onto the surface of the substrate to perform non-immersion cleaning. The confirmation of the effect of removing the surfactant is visually confirmed.

  Immediately after the finish cleaning step A3, compressed air or nitrogen gas is sprayed onto the substrate surface in the purge step A4 to blow off the attached cleaning liquid. By this process, the cleaning liquid that has entered under the mounted component or inside the connector can be blown off.

  As an example of cleaning by the above-described cleaning process, FIG. 4 shows an example of the cleaning effect of an electronic circuit board that is soiled by digestive fluid, digestive gas, and oil components at the fire site and electronic components mounted on the board.

As shown in the figure, the substrate 1, the contactor, the relay, and the electromagnetic switch (MCCB) before cleaning are each restored to an equivalent salt content of 0.1 mg / cm ² or less after cleaning, and the insulation resistance is improved by this cleaning process. It was confirmed that the value recovered to a predetermined value or more.

  This cleaning method can also be used for electrical products of large electrical equipment. For example, the power electronics element is coated with grease for heat dissipation between the power electronics element and the heat radiating plate. However, since the cleaning liquid shown here does not dissolve the grease, it can be washed in a circle.

  Thus, it was confirmed that this cleaning process is an effective method even when urgent recovery is required after a disaster such as a fire.

  There is a case in which the surface of a structure such as a casing of an electronic device in which a non-energized part is installed in the atmosphere is desired for the electronic device. For example, there is a painted surface such as a fixture of lighting equipment attached to a tunnel placed in the atmosphere. Such instruments and the like may be corroded by anti-corrosion because the painted surfaces of the instruments are corroded by sea salt particles, exhaust gas, and other dust in the atmosphere.

  Example 3 is a cleaning method in such a case. Example 3 differs from Example 1 and Example 2 in that a drip-proof finishing process that suppresses corrosion between the purge process A4 and the drying process A5 is performed. Different points are added. The other cleaning steps are the same as those in Example 1 or Example 2, and therefore the description thereof is omitted.

  The drip-proof finishing process in this case will be described in detail. The finishing agent used in this finishing step is 0.1 to 1 of an antistatic agent or a drip-proof material in an alcohol aqueous solution of 57% by weight of distilled or ion-exchanged water, 41% by weight of ethyl alcohol and 2% by weight of isopropyl alcohol. Made by adding 0.0% by weight.

  As the antistatic agent, for example, an anionic surfactant alkylbenzene sulfonate, a nonionic surfactant polyoxyethylene alkyl ether, or the like is used. Moreover, as a drip-proof agent, sorbitan fatty acid monoestal is used, for example.

  Then, this finishing agent is sprayed onto the surface of the cleaned structure, and it is visually confirmed that the entire surface is wet with this finishing agent. Then, the surface is naturally dried or warm air dried. Since the antifouling effect by this finishing agent cannot withstand long-term corrosion prevention, it is desirable to perform this finishing cleaning periodically.

  Such cleaning can be applied not only to electronic devices and electrical devices, but also to cleaning of insulating materials such as epoxy resins, unsaturated polyester resins, and phenol resins, and the objects to be cleaned are limited to those described above. It is not a thing.

  The electronic device may be mounted under a specific environment, for example, under the floor of a vehicle or the like. Deterioration such as pit-like pitting corrosion progresses by using various metal structures placed in such an environment for a long period of time. FIG. 5 is a flowchart of a cleaning process for aluminum cooling fins of electronic equipment mounted under the vehicle floor, for example. This will be described below with reference to FIG.

  This cleaning process includes a dust removing process B1 for purging dust with compressed air, a warm water cleaning process B2 for dissolving and removing ionic fouling substances that cause corrosion by spraying hot water, and a corrosion inhibitor finishing cleaning process B3 by spraying a corrosion inhibitor. And a purge step B4 for purging the anticorrosion finish liquid.

  Next, details of each step will be described with reference to the same drawing. First, in the dust removing step B1, dust is removed by blowing compressed air. Since dust that has entered inside cannot be removed by suction removal, it is removed by spraying.

  Next, in the warm water cleaning step B2, warm water of 80 ° C. is sprayed onto the fin surface and inside to dissolve and remove the ionic fouling substances that cause corrosion. The higher the temperature of the hot water, the more effective.

  As shown in FIG. 6, when the effect of cleaning with the temperature of the cleaning water in the warm water cleaning step B2 at 15 ° C. and 80 ° C. is evaluated by the adhesion amount of chlorine ions adhering to the inner surface of the fin, But more effective. As a result of testing various kinds of metals while changing the temperature of the washing water in this way, it was confirmed that the solubility characteristics with respect to the ionic fouling substances are almost equal if the temperature is 60 ° C. or higher.

  Next, in the anticorrosion finish cleaning step B3, a 30 wt% or more alcohol aqueous solution to which a corrosion inhibitor is added is sprayed onto the surface and the inner surface of the fin. In this step, cleaning of the gaps where water having a large surface tension did not permeate in the warm water cleaning step B2 and anticorrosion finish cleaning of the entire fin are performed.

  The composition of the cleaning liquid used in the anticorrosion finishing cleaning step B3 is, for example, 30% by weight or more of an aqueous alcohol solution containing ethyl alcohol, isopropyl alcohol and isopropyl alcohol at an arbitrary concentration, and sodium metasilicate as a corrosion inhibitor to 0.1 to A mixed solution in which the weight% and the remainder are distilled water or ion-exchanged water is used.

表１は、鉄、アルミニュム、銅に対する防食効果を、腐食抑制材の種類とその添加濃度変えた７０℃の温水に２５０時間浸漬したときの夫々の金属腐食度合いを調べて、この浸漬試験による夫々の金属の変色度合いから腐食抑制剤の効果を調べた結果を示す。 The type, addition concentration, and alcohol concentration of the corrosion inhibitor are selected according to the type of target metal from the results of the evaluation test shown in (Table 1). Hereinafter, the anticorrosion effect by a cleaning test for typical metals used in electronic devices will be described.

Table 1 shows the anticorrosion effect on iron, aluminum and copper, and the degree of corrosion of each metal when immersed in warm water of 70 ° C. with different types of corrosion inhibitors and their added concentrations for 250 hours. The result of investigating the effect of the corrosion inhibitor from the degree of discoloration of the metal of

  As shown in Table 1, the temperature of the hot water to which this corrosion inhibitor was added was set to 70 ° C., and each metal was immersed. When 250 hours had elapsed, discoloration occurred in the case of iron or aluminum and in the case of sodium metasilicate. In the case of copper, no discoloration was observed in the case of benzotriazole, indicating that each corrosion inhibitor has a high anticorrosive effect.

  Therefore, when there are a plurality of metal structures to be cleaned, anticorrosion finish cleaning is performed with a cleaning solution in which 0.01 to 0.1% by weight of each of silicate-based sodium metasilicate and riazole-based bezontriazole is added. I do.

また、表２は、アルコール濃度を変えた防食仕上げ洗浄液２０℃に、鉄、アルミニュム、銅を１２００時間の長期間浸漬後、夫々の金属の変色状態から腐食の状態を観察し、アルコール濃度の評価結果を示す。 Further, as shown in Table 1, it has been confirmed that the corrosion inhibitor has an anticorrosive effect if the addition concentration of the corrosion inhibitor is about 0.01% by weight or more in any case. (Table 1) shows the results of the immersion test. However, since the actual cleaning is performed by non-immersion cleaning, it is desirable that the concentration of the corrosion inhibitor added be increased to about 0.1% by weight.

Table 2 shows the evaluation of the alcohol concentration by observing the state of corrosion from the discolored state of each metal after immersing iron, aluminum, and copper for a long period of 1200 hours in an anticorrosive finish cleaning solution having a changed alcohol concentration at 20 ° C. Results are shown.

  As shown in the table, since it has been confirmed that the alcohol concentration is in the range of 30 to 60% by weight, the anticorrosion effect has been sufficiently confirmed, so it is more economical to set the alcohol concentration as low as possible.

  Next, in the purge step B4, the anticorrosion finish cleaning liquid on the entire fin is blown off with compressed air. Even if the cleaning liquid is not completely blown off, the corrosion is not added to the remaining cleaning liquid, so that the metal is not corroded. However, since the effect of this anticorrosion finish cleaning is limited, it is desirable to periodically perform the anticorrosion finish cleaning.

  In this embodiment, the anti-corrosion finish cleaning step B3 of the aluminum cooling fin has been described. However, when the metal to be constructed is copper, as shown in Table 1, the corrosion inhibitor is replaced with benzotriazole instead of sodium metasilicate. It is effective when added.

  Thus, effective anticorrosive finish cleaning can be performed by selecting a corrosion inhibitor depending on the metal to be cleaned.

  The cleaning methods of the various processes described above are applied to the cleaning of insulators used in electronic devices and electrical devices. As the quality determination method for these cleanings, the method of determining from the correlation between the equivalent salt content and the insulation resistance described above is effective.

As the pass / fail judgment after cleaning, the equivalent salt content on the surface is measured, and insulation at an arbitrary temperature and humidity is determined from the correlation curve between the equivalent salt content (NaClmg / cm ² ) and the insulation resistance (Ω) measured in advance. Try to estimate the resistance.

  For example, FIG. 7 shows an equivalent salinity of an unsaturated polyester insulating plate using calcium carbonate as an inorganic filler at 40 ° C. under relative humidity conditions of 10% RH, 65% RH, 80% RH, and 95% RH. And the correlation between the insulation resistance.

  If such correlation data is owned as a parameter for each material to be cleaned, the insulation resistance can be estimated even under the worst temperature and humidity conditions throughout the year. If a pass / fail judgment criterion is set in advance for each cleaning material, the pass / fail judgment of the cleaning result can be confirmed quantitatively in a short time immediately from the measurement result of the equivalent salinity.

  Furthermore, the present invention has been described with reference to the above-described typical pollution model. However, the present invention is not limited to these examples, and includes not only electronic devices but also various large-sized electric devices and the like, the contamination points, and the contamination. It is possible to vary the combination and selection of the cleaning methods shown here, the concentration of the cleaning liquid, the type and concentration of the additive, the temperature of the cleaning water, etc., depending on the state, and deviates from the gist of the present invention. Various modifications can be made without departing from the scope.

Explanatory drawing of the washing | cleaning process of an electronic circuit board. Explanatory drawing of the drying time of an electronic circuit board. Explanatory drawing of the washing | cleaning effect (measurement of an equivalent salt content) of an electronic circuit board. Explanatory drawing of the washing | cleaning effect of an electronic component. The flowchart explaining the washing | cleaning process of a metal structure. Explanatory drawing of the effect by warm water washing | cleaning of a metal structure. Measurement example showing the relationship between equivalent salt content and surface insulation resistance.

Explanation of symbols

A1 Dust removal process A2 Preliminary cleaning process A3 Finishing cleaning process A4 Purge process A5 Drying process B1 Dust removal process B2 Warm water cleaning process B3 Anticorrosion finishing cleaning process B4 Purge process 1a Electronic circuit board 1b Brush 1c Vacuum cleaner 2c Antistatic container 2d Substrate rack 2e Sprayer 4g Air gun 5h Drying furnace

Claims (10)

A first cleaning step of non-immersing and cleaning an electronic device including a contaminated energized portion with a first alcohol aqueous solution of 60% by weight or less;
A second cleaning step of non-immersing and cleaning the residue of the first cleaning step with 60% by weight or less of a second aqueous alcohol solution;
A purge step for removing residues after the second cleaning step;
An electronic device cleaning method comprising: a drying step of drying the electronic device after the purge step. A first cleaning step of non-immersing and cleaning an electronic device including a contaminated energized portion with a 40 to 60 wt% first alcohol aqueous solution to which a surfactant is added;
A second cleaning step of non-immersing the residue of the first cleaning step with a 60% by weight or less second alcohol aqueous solution not containing a surfactant;
A purge step for removing residues after the second cleaning step;
An electronic device cleaning method comprising: a drying step of drying the electronic device after the purge step. 3. The electronic device according to claim 1, wherein in the drying step, the residue on the surface of the electronic device in the second cleaning step is wiped with an alcohol liquid, heated in a drying furnace, and dried under reduced pressure. Cleaning method. A first cleaning step of non-immersing and cleaning the non-conducting portion of the soiled electronic device with a 40 to 60 wt% first alcohol aqueous solution to which a surfactant is added;
A second cleaning step of non-immersing the residue of the first cleaning step with a 60% by weight or less second alcohol aqueous solution not containing a surfactant;
A purge step for removing residues after the second cleaning step;
After the purge step, a drip-proof finishing step of spraying a third alcohol aqueous solution of 60% by weight or less to which an antistatic agent or a drip-proof agent is added;
An electronic device cleaning method comprising: a drying step of drying the electronic device after the drip-proof finishing step. The surfactant is a mixture of a nonionic surfactant and an anionic surfactant, and is added in an amount of 0.1 to 0.3% by weight of the first aqueous alcohol solution. Item 5. A method for cleaning an electronic device according to item 2 or item 4. The antistatic agent or the drip-proofing agent is any one of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and a mixture thereof. To clean electronic equipment. A first hot water cleaning step of non-immersing and cleaning the metal part of the damaged electronic device with hot water of 60 ° C. or higher;
A second anti-corrosion finish cleaning step comprising non-immersing and cleaning with an aqueous alcohol solution of 30% by weight or more to which a corrosion inhibitor is added. The corrosion inhibitor is a triazole type or silicate type, or both are mixed, and the amount added is 0.01 to 0.2% by weight of the 30% or more alcohol aqueous solution. The method for cleaning an electronic device according to claim 7. 9. The electron according to claim 8, wherein the corrosion inhibitor is silicate-based when the metal part to be cleaned is iron and aluminum, and triazole-based when the metal part to be cleaned is copper. How to clean the equipment. Measure the equivalent salt content and surface insulation resistance of the insulation part to be measured in advance, store the correlation between the equivalent salt content and surface insulation resistance as a database, and calculate the equivalent salt content of the surface to be measured. An evaluation method for cleaning an electronic device that measures and compares the measurement result with the database to determine whether or not the measured value is recovered within a predetermined surface insulation resistance range.

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