JP2009283842A - Method of cleaning metal plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of cleaning a metal plate which prevents poor cleaning caused by solidification of a cream solder by absorption of a cleaning liquid, and can clean wholly and cleanly a printing pattern of the metal plate. <P>SOLUTION: The method is provided for cleaning the metal plate 1 used for printing a cream solder on a printed wiring board. The metal plate 1 is roughly cleaned sequentially from the down side of the metal plate 1 supported at a certain angle against the horizontal direction by horizontally reciprocating a spray nozzle 14 while an aqueous cleaning liquid is being sprayed from the spray nozzle 14 to the metal plate 1. After the rough cleaning, the metal plate 1 is finish-cleaned sequentially from the upper side of the metal plate 1 by horizontally reciprocating the spray nozzle 14 while the cleaning liquid is being sprayed from the spray nozzle 14 to the metal plate 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for cleaning a metal plate used for printing cream solder on a printed wiring board.

  Conventionally, as a method of applying cream solder to a soldered portion of a printed wiring board, a method of printing and applying cream solder by a screen printing method using a metal plate made of stainless steel or nickel has been widely adopted. Yes. However, when cream solder is printed by this screen printing method, the solvent of the cream solder is volatilized over time and the cream solder is gradually solidified. There is a problem in that the metal plate is solidified and deposited on the inner surface of the hole of the printing pattern of the metal plate, particularly the inner surface of the end of the hole, and the metal plate is clogged, and a desired print quality cannot be obtained. For this reason, the metal plate used for printing is washed every set time to remove the solidified product of cream solder deposited on the inner surface of the hole. As such a metal plate cleaning device, a cleaning device that sprays a cleaning liquid from a cleaning nozzle at a high pressure to clean the metal plate (for example, see Patent Document 1), or a metal that vibrates the cleaning liquid with an ultrasonic vibrator. A cleaning device for cleaning a plate (see, for example, Patent Document 2) has been proposed.

  In the cleaning apparatus described in Patent Document 1, a metal plate is attached to a holder and supported vertically, and the holder is slid vertically while spraying cleaning liquid on both the front and back surfaces of the metal plate with a pair of cleaning nozzles. And the metal plate is cleaned. The metal plate, the holder that supports the metal plate, and the washing nozzle are entirely covered with a casing. Further, a funnel-shaped partition plate is formed below the casing, and is ejected from the washing nozzle. After the metal plate is cleaned, the cleaning liquid can be collected in the tank through the partition plate.

  In the cleaning apparatus described in Patent Document 2, a metal plate is disposed substantially in parallel with a slight gap with respect to a longitudinal vibration plate to which an ultrasonic vibrator is attached, and the vibration plate is placed by the ultrasonic vibrator. While vibrating, the cleaning liquid is caused to flow between the diaphragm and the metal plate, and the metal plate is ultrasonically cleaned.

  On the other hand, water or electrolyte aqueous solution is electrolyzed to produce electrolytic alkaline water having a hydrogen ion index of pH 9 or more and 12 or less, and this is pressurized to mechanical parts, electrical parts, automobiles, building outer walls, civil engineering structures. There has been proposed a cleaning device that cleans an object to be cleaned such as a surface by spraying the object with a nozzle (see, for example, Patent Document 3).

  In addition, as a cleaning device for removing contaminants adhering to the surface of the substrate, a spray nozzle that ejects droplets toward the substrate, and a spray nozzle connected to the spray nozzle, a liquid such as pure water is put into the spray nozzle. A liquid supply means for supplying; a gas supply means connected to the injection nozzle for supplying gas into the injection nozzle; and provided in the injection nozzle for mixing the liquid and the gas supplied into the injection nozzle; A device including a mixing unit that converts liquid into droplets has been proposed (see, for example, Patent Document 4).

JP-A-10-71705 JP 2000-107711 A JP 2001-327934 A JP-A-8-318181

  By the way, in the cleaning method described in Patent Document 1, not only the running cost is increased because a large amount of glycol-based or alcohol-based organic solvent is injected from the cleaning nozzle, but the waste liquid must be handled as industrial waste. There was a problem that the load was very large. In addition, since organic solvents have a strong odor, the load on the worker's body is not small and improvement of the working environment is desired. On the other hand, in the cleaning method described in Patent Document 2, it is possible to significantly reduce the cleaning liquid to be used. However, as in the cleaning method described in Patent Document 1, it is necessary to use a glycol-based or alcohol-based organic solvent as the cleaning liquid. There is a problem in that the liquid must be handled as industrial waste, which increases the environmental load.

  In addition to the methods described in Patent Documents 1 and 2, the metal plate cleaning method includes wiping with a cloth dipped in a solvent, a method of blowing off using an air gun, a method of sucking with a suction nozzle, etc. In recent years, however, the pitch of printed wiring boards has become very narrow, and along with this, the holes in the printed pattern of metal plates have become very narrow, such as 0.22 mm width and 0.14 mm width. Therefore, in these cleaning methods, it is difficult to completely remove the solder remaining in the printed pattern hole.

  On the other hand, a cleaning method using electrolytic alkaline water as described in Patent Document 3 and a liquid such as air and pure water are mixed in a nozzle as described in Patent Document 4, and high-speed droplets are discharged from the nozzle. The cleaning method by spraying and cleaning has not yet been adopted as a cleaning method for metal plates, and it is possible to effectively and efficiently clean metal plates having printed pattern holes with a width of 0.22 mm or 0.14 mm. Actually, no clean method has been established yet.

  In addition, as a result of performing a test for cleaning a metal plate using an aqueous cleaning liquid such as electrolytic alkaline water or pure water as described in Patent Documents 3 and 4, Patent Inventors of Patent Documents 1 and 3 using an organic solvent, As with the cleaning method described in 2, the metal plate is placed vertically and the metal plate is washed in order from the top to prevent re-adhesion of the washed solder balls. It has been found that there is a problem that defects occur. And as a result of earnestly examining the cause, in the cleaning methods described in Patent Documents 1 and 2, since the cream solder flux is dissolved in the organic solvent, the cleaned organic solvent moves down along the metal plate. However, when an aqueous cleaning solution such as electrolytic alkaline water or pure water as described in Patent Documents 3 and 4 is used, it has been found that the flux absorbs the cleaning water and solidifies, resulting in poor cleaning.

  An object of the present invention is to provide a metal plate cleaning method capable of preventing a defective cleaning due to the cream solder absorbing and solidifying the cleaning liquid and cleaning the printing pattern of the metal plate as a whole. .

  In the case where the metal plate is washed vertically with an aqueous cleaning solution, the inventor performs the cleaning from the upper side of the metal plate, and the cream solder adhering to the lower side of the cleaning position of the metal plate. The flux absorbs the cleaning liquid flowing down along the metal plate, and it is found that the flux is solidified, so that defective cleaning is likely to occur. By cleaning the metal plate in order from the lower side, along the metal plate The present invention has been completed with the idea that the solidification of the flux due to contact with the cleaning liquid flowing down is prevented as much as possible and the metal plate can be cleaned cleanly.

  A metal plate cleaning method according to the present invention is a metal plate cleaning method used for printing cream solder on a printed wiring board, and the metal plate is attached at a certain angle with respect to a horizontal direction. In a supported state, while spraying an aqueous cleaning liquid from the spray nozzle toward the metal plate, the spray nozzle is reciprocated in the horizontal direction to roughly clean the metal plate in order from the lower side. In the present invention, the aqueous cleaning liquid means water such as alkaline water, ion exchange water, or pure water. The alkaline water means water having a pH of 7.5 or more, which is composed of alkaline electrolyzed water, alkaline aqueous solution, alkaline ionized water, or the like.

  In this cleaning method, the metal plate is washed in a state of being supported at a certain angle with respect to the horizontal direction, so that the cleaning liquid sprayed on the metal plate flows down along the metal plate. Since the metal plate is roughly cleaned in order from the bottom, even when an aqueous cleaning solution is used as the cleaning solution, the cleaning solution sprayed onto the metal plate will flow down along the portion of the metal plate that has been cleaned. Thus, it is possible to effectively prevent poor cleaning due to the fact that the solder paste flux adhering to the metal plate absorbs and solidifies the aqueous cleaning liquid, and the metal plate can be cleaned cleanly. Moreover, since it is cleaned only with an aqueous cleaning solution such as alkaline water without using an organic solvent, the waste liquid after cleaning does not need to be handled as industrial waste, and the environmental load can be significantly reduced. Since there is no odor compared to solvents, the working environment can be improved. In addition, since an aqueous cleaning liquid such as alkaline water is not volatile like an organic solvent, it does not need to be replenished at all times, and only needs to be washed with water and dried after washing, so that the running cost is low.

  Here, in the preferred embodiment, after the rough cleaning, it is preferable to finish and wash the metal plate in order from the upper side by reciprocating the injection nozzle in the horizontal direction while spraying the cleaning liquid from the injection nozzle toward the metal plate. is there. If the finish cleaning is performed in order from the upper side in this way, even if a part of the cream solder is reattached to the metal plate in the rough cleaning, it can be cleaned cleanly.

  In the rough cleaning, the cleaning liquid is sequentially sprayed on the formation pattern of the printing pattern of the metal plate to perform the rough cleaning, and in the finishing cleaning, the cleaning liquid is sequentially sprayed on the entire surface of the metal plate to perform the final cleaning. Is also a preferred embodiment. If comprised in this way, the cleaning time by rough cleaning can be shortened as much as possible, and the cleaning time can be shortened as a whole. In addition, regarding the formation range of the most important printed pattern of the metal plate, the cream solder can be cleaned cleanly by two cleanings.

  It is also a preferred embodiment to supply the cleaning liquid to the spray nozzle in a state heated to 30 ° C to 60 ° C. The temperature of the cleaning liquid supplied to the spray nozzle is preferably set to 30 ° C. or higher in consideration of the improvement in cleaning power due to softening of the solder solder flux. Since a force falls, it is preferable to set to 30 to 60 degreeC.

  Alkaline water is used as the cleaning liquid, and the cleaning liquid and compressed air are mixed in the injection nozzle, and the cleaning liquid is atomized and sprayed at high speed from the injection nozzle toward the metal plate. It is also a preferred embodiment to clean the metal plate.

  In this cleaning method, alkaline water and compressed air are mixed in the spray nozzle and sprayed from the spray nozzle onto the metal plate in a state of being finely divided to a size that can pass through the holes in the print pattern. The finely divided alkaline water is allowed to collide with the solder balls and flux inside the printed pattern without energy loss, so that the solder balls and flux can be effectively and efficiently removed. In addition, alkaline water has the ability to saponify and disperse oil, so it has the effect of saponifying and dispersing the flux to make it easier to clean. This makes flux attached to the metal plate and flux in the holes of the printed pattern more efficient. And cleanly removed. Furthermore, alkaline water has the property that it is more easily made finer than ion-exchanged water and organic solvents, and it is made finer to a smaller diameter than holes of very narrow printed patterns such as 0.22 mm width and 0.14 mm width. Therefore, the solder and flux in the hole can be removed efficiently.

  When alkaline water is used as the cleaning liquid, it is a preferred embodiment to set the hydrogen ion index of the cleaning liquid to pH = 10.5 to 12.0. That is, if the pH is too high, the metal part of the solder and the metal plate will be corroded, and if the pH is too low, cleaning for a long time is required, which is not preferable in view of drainage treatment and running costs. The pH is preferably set to 10.5 or more and 12.0 or less.

  When alkaline water is used as the cleaning liquid, it is also a preferred embodiment to set the volume ratio of the compressed air and the cleaning liquid to 500: 1 to 700: 1. In other words, when the volume ratio of compressed air is large, the amount of alkaline water that collides with the solder is reduced, so that sufficient cleaning power cannot be obtained, and in order to completely remove the solder and flux from the printed pattern Long-term cleaning is required. In addition, when the volume ratio of compressed air is too small, alkaline water cannot be sufficiently finely granulated. Therefore, in a very narrow width such as 0.22 mm width or 0.14 mm width, alkaline water particles are not printed. It cannot pass through the hole and a sufficient cleaning effect cannot be obtained. Similarly, when the volume ratio of the compressed air is too small, the sprayed alkaline water forms a water film on the surface of the metal plate, which causes a phenomenon in which collision of new particles occurs, resulting in a cleaning effect. It will be reduced.

  It is also a preferred embodiment that an injection nozzle is provided on both sides of the metal plate, and the metal plate is cleaned while spraying a cleaning liquid from both injection nozzles on both sides of the metal plate. Although it is possible to wash the metal plate one side at a time, the nozzles are provided on both sides of the metal plate, and a water-based cleaning solution such as alkaline water is sprayed simultaneously on the front and back surfaces of the metal plate. This is preferable because the cleaning efficiency of the metal plate can be increased. Further, in this case, it is preferable to prevent the cleaning power from being deteriorated due to the collision of the cleaning liquids ejected from the two ejection nozzles by shifting the spraying positions of the cleaning liquids by the two ejection nozzles. As a method of shifting the spraying position, it is possible to shift the spraying position by setting the spraying angle of the cleaning liquid in the two spraying nozzles to different angles, or setting the spraying nozzles at the same position while changing the position of both spraying nozzles to X. The spray position can be shifted by shifting in the axial direction or the Y-axis direction, or the spray position can be shifted by combining both. As the most preferable method, it is preferable to shift the spraying position by shifting the positions of both the spray nozzles in the X-axis direction or the Y-axis direction while setting the spraying direction of both the spraying nozzles in the direction orthogonal to the metal plate.

  It is also a preferred embodiment that the distance between the tip of the spray nozzle and the metal plate is set to 3 to 8 mm. If the distance between the tip of the spray nozzle and the metal plate is too long, the collision energy of the cleaning liquid cannot be sufficiently applied to the cream solder adhering to the metal plate, and if it is too short, the cleaning liquid is sufficiently refined. The cleaning efficiency is reduced by the collision of the sprayed cleaning liquid with the cleaning liquid bounced back by the metal plate and the distance between the tip of the injection nozzle and the metal plate is set to 3 to 8 mm. It is preferable to do.

  The injection nozzle includes a nozzle body having a compressed air flow path and a cleaning liquid flow path, and a nozzle cap that is detachably attached to the tip of the nozzle body. A partition wall protruding toward the injection port is formed at the tip of the nozzle body, and this partition allows a space between the nozzle body and the nozzle cap to be formed in a first space on both sides of the partition wall and a second space on the tip side of the partition wall. The space is divided into three spaces, and a pair of the first space and the second space are communicated with each other through a constriction gap formed between the tip of the partition wall and the nozzle cap, and the flow path of the compressed air is paired with the first space. Each of the openings is opened in one space, and the flow path of the cleaning liquid is opened from the tip of the partition wall to the second space, and the cleaning liquid and the compressed air are mixed in the second space to make the cleaning liquid finer. Prefer Correct is in the form of implementation.

  In this jet nozzle, the compressed air is supplied to the first space on both sides of the partition wall through the flow passage inside the nozzle body, and supplied to the second space while being accelerated from the first space through the throttle gap to a speed close to the speed of sound. Is done. On the other hand, the cleaning liquid is supplied to the second space on the tip side of the partition through the flow passage formed in the partition, is mixed with high-speed compressed air in the second space, is atomized, and is compressed from the injection port. Spouted with air. Then, the finely granulated high-speed cleaning liquid ejected from the injection port is sprayed toward the metal plate to clean the metal plate. For this reason, it is possible to effectively and efficiently remove the solder balls and the flux by causing the finely divided cleaning liquid to collide with the solder balls and the flux inside the print pattern without energy loss.

  In the spray nozzle, the spray port may be formed in an elongated hole shape having an aspect ratio of 40 or more. The injection port can be formed in a circular shape, but it is preferable to form the injection port in a long hole shape with an aspect ratio of 40 or more so that a large area metal plate can be cleaned in a short time.

  According to the method for cleaning a metal plate according to the present invention, the metal plate is roughly cleaned in order from the lower side. Therefore, even when an aqueous cleaning liquid is used as the cleaning liquid, the cleaning liquid sprayed on the metal plate is It will flow down along the part where the cleaning of the metal plate has been completed, and the solder paste flux adhering to the metal plate can effectively prevent the cleaning failure caused by solidifying the water-based cleaning liquid and solidify the metal plate. Can be washed. Moreover, since it is cleaned only with an aqueous cleaning solution such as alkaline water without using an organic solvent, the waste liquid after cleaning does not need to be handled as industrial waste, and the environmental load can be significantly reduced. Since there is no odor compared to solvents, the working environment can be improved. In addition, since an aqueous cleaning liquid such as alkaline water is not volatile like an organic solvent, it does not need to be replenished at all times, and only needs to be washed with water and dried after washing, so that the running cost is low.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The metal plate cleaning method according to the present invention uses a metal plate cleaning apparatus 10 as shown in FIGS. 1 and 2 to support the metal plate 1 at a fixed angle with respect to the horizontal direction. The metal plate 1 is roughly cleaned in order from the lower side by reciprocating the spray nozzle 14 in the horizontal direction while spraying an aqueous cleaning liquid from the spray nozzle 14 toward the nozzle 1.

  As shown in FIGS. 1 and 2, the metal plate cleaning device 10 is composed of a cleaning device main body 11 for cleaning the metal plate 1 by spraying finely pulverized alkaline water as a cleaning solution onto the metal plate 1, and a cleaning solution. And an alkaline water supply device 30 for supplying alkaline water. In the present embodiment, a case where the metal plate cleaning method of the present invention is applied to a metal plate cleaning apparatus 10 that sprays alkaline water as a cleaning liquid onto the metal plate 1 to clean the metal plate 1 will be described. The present invention can be similarly applied to an existing metal plate cleaning apparatus that sprays an aqueous cleaning liquid other than alkaline water, such as ion exchange water or pure water, onto the metal plate 1 to clean the metal plate 1.

  A frame-shaped reinforcing frame 13 is integrally provided on the outer peripheral portion of the metal plate 1, and the metal plate 1 is supported in the housing 12 of the cleaning device body 11 at a certain angle with respect to the horizontal direction, The cleaning liquid sprayed on the metal plate 1 is configured to flow down along the metal plate 1. Although the inclination angle with respect to the horizontal direction of the metal plate 1 can be set arbitrarily, in order to configure the cleaning device main body 11 as small as possible, as shown in FIG. 1 and FIG. It is preferable to support the housing 12 in the vertical direction.

  A pair of alkaline water injection nozzles 14 for injecting alkaline water to the metal plate 1 are provided on both sides before and after the metal plate 1 so as to face each other. These moving means are supported so as to be movable in conjunction with each other in the X-axis direction and the Y-axis direction. As the moving means, it is possible to adopt any configuration, for example, one having a guide rod in the X-axis direction and the Y-axis direction and a motor for moving in the X-axis direction and the Y-axis direction. Can be adopted.

  As shown in FIG. 2, the front and rear alkaline water injection nozzles 14 are opposed to each other with the alkaline water ejection direction orthogonal to the metal plate 1 and the alkaline water ejection position shifted by a certain distance S in the X-axis direction. Is provided. Thereby, it is possible to prevent the alkaline water jetted from the front and rear alkaline water jet nozzles 14 from colliding with each other and to interfere with each other, to prevent the cleaning effect from being lowered, and to remove with the alkaline water jetted from the one nozzle 14. The solder 5 and the flux 4 (see FIGS. 9 and 10) that could not be formed can be removed by alkaline water sprayed from the other nozzle 14. The distance G between the tip of the alkaline water spray nozzle 14 and the metal plate 1 is set to 3 to 8 mm. If the distance G between the tip of the alkaline water injection nozzle 14 and the metal plate 1 is too long, the collision energy of alkaline water cannot be sufficiently applied to the solder 5 and the flux 4 attached to the metal plate 1 and is short. If the alkaline water is too fine, the alkaline water collides with the metal plate 1 without being sufficiently refined, and the sprayed alkaline water collides with the alkaline water bounced back by the metal plate 1, so that the cleaning efficiency is lowered. The distance G between the tip of the injection nozzle 14 and the metal plate 1 is preferably set to 3 to 8 mm.

  As shown in FIGS. 3 to 6, the alkaline water injection nozzle 14 is detachably attached to a nozzle body 17 in which a compressed air flow passage 15 and an alkaline water flow passage 16 are formed, and a tip end portion of the nozzle body 17. A nozzle cap 18, a retainer 19 for fixing the nozzle cap 18 to the nozzle body 17, and a plug 21 for connecting a compressed air supply pipe 20 to the nozzle body 17. In addition, it is also possible to employ | adopt the thing other than what is illustrated in FIGS. 3-6 as an injection nozzle.

  A nozzle hole 18 is formed in the tip of the nozzle cap 18 in the form of an elongated hole that is elongated in the vertical direction, and a partition wall 23 is formed at the tip of the nozzle body 17 so as to project toward the spray port 22. The space between the body 17 and the nozzle cap 18 is partitioned into three spaces: a first space 24 on both sides of the partition wall 23 and a second space 25 on the tip side of the partition wall 23. A diaphragm gap 26 is formed between the tip of the partition wall 23 and the nozzle cap 18, and the first space 24 and the second space 25 are communicated with each other via the diaphragm gap 26. A pair of compressed air flow passages 15 are formed in the nozzle body 17, and the downstream portions of the two flow passages 15 are branched into six branch passages 15 a and opened into two first spaces 24, respectively. The flow path 16 is open to the second space 25 at the tip of the partition wall 23.

  In the alkaline water injection nozzle 14, the compressed air is supplied to the two first spaces 24 through the pair of flow passages 15, and further supplied symmetrically to the second space 25 through the throttle gap 26. . The flow passage 15 has a smaller passage cross section in the branch passage 15a, and in the first space 24, the passage cross section becomes smaller toward the throttle gap 26 side. Therefore, the compressed air is directed to the throttle gap 26 side in accordance with Bernoulli's law. As it goes, it is accelerated and flows into the second space 25 at a high speed. On the other hand, the alkaline water is supplied to the second space 25 through the flow passage 16. However, since the cross-sectional area of the flow passage 16 is reduced in the partition wall 23, the alkaline water is accelerated in the partition wall 23. Thus, the second space 25 is supplied. In the second space 25, the compressed air and the alkaline water are mixed at a high speed, whereby the alkaline water is atomized in the second space 25, and is jetted to the outside from the jet port 22 in this state. Become. By the way, alkaline water has the property of being easily made finer than water-based cleaning liquids such as ion-exchanged water and pure water, and the finer alkaline water particles form holes 3 in the printed pattern 2 as shown in FIG. Since the diameter can be easily passed, it can collide with the solder ball 5 inside the printed pattern 2 and remove the solder 5 with the pressure energy. Furthermore, since alkaline water has the ability to saponify and disperse the oil, it has the effect of saponifying and dispersing the flux 4 to facilitate cleaning. As a result, the flux 4 attached to the metal plate 1, the flux 4 in the printed pattern 2, and the solder 5 are removed, and cleaning is realized.

  The opening width W of the injection port 22 is preferably set to 0.3 mm to 0.7 mm, and the opening length L is preferably set to 20 mm to 30 mm. The aspect ratio (L / W) of the injection port 22 is preferably set to 40 or more. The injection port 22 may be formed in a circular shape, but may be formed in a long hole shape with an aspect ratio (L / W) of 40 or more so that the large-area metal plate 1 can be cleaned in a short time. preferable.

  The moving speed of the alkaline water spray nozzle 14 by the moving means is preferably set to 5 mm / sec or more and 20 mm / sec or less. When the moving speed is less than 5 mm / sec, the cleaning processing speed is slow, and when it exceeds 20 mm / sec, a cleaning failure occurs. Moreover, it is preferable to set the injection amount of alkaline water from the alkaline water injection nozzle 14 to 500 cc / min or more and 700 cc / min or less. When the injection amount is less than 500 cc / min, defective cleaning occurs, and when it exceeds 700 cc / min, the consumption of alkaline water increases and it is necessary to employ a large-sized alkaline water supply device 30. And a water film of alkaline water is formed on the surface of the metal plate 1, and the problem arises that the cleaning ability is reduced.

  The volume ratio of compressed air and alkaline water is set to 500: 1 to 700: 1. That is, when the volume ratio of compressed air is large, the amount of alkaline water that collides with the solder 5 is reduced, so that sufficient cleaning power cannot be obtained, and the solder 5 and the flux 4 are completely removed from the printed pattern 2. In order to do so, a long cleaning time is required. In addition, when the volume ratio of compressed air is too small, alkaline water cannot be sufficiently finely granulated. Therefore, alkaline water particles are printed in a very narrow width such as 0.22 mm width or 0.14 mm width. Cannot pass through the hole 3, and a sufficient cleaning effect cannot be obtained. Similarly, when the volume ratio of the compressed air is too small, the sprayed alkaline water forms a water film on the surface of the metal plate 1 and a phenomenon that the collision of new particles is prevented occurs. The effect will be reduced.

  As the compressed air, so-called factory air compressed by the compressor 27 is used, but it is preferable that oil and excess water are sufficiently removed through a filter and a dryer. The pressure of the compressed air varies depending on the ratio of the cross-sectional area of the throttle gap 26 and the flow path 15 of the compressed air. However, if the pressure is low, a sufficient flow rate and flow velocity cannot be obtained. In the embodiment, it is set to 0.5 MPa.

  The cleaning device main body 11 is provided with heating means 29 for supplying the alkaline water supplied from the alkaline water supply device 30 to the alkaline water injection nozzle 14 in a state heated to 30 ° C. to 60 ° C. By heating the alkaline water, the cream solder flux adhering to the metal plate 1 is softened to improve the cleaning power. The temperature of the alkaline water supplied to the alkaline water spray nozzle 14 is preferably set to 30 ° C. or higher, which is the softening temperature of the cream solder flux. If the temperature exceeds 60 ° C., the pH of the cleaning liquid is lowered and the cleaning power is lowered. Therefore, it is preferable to set to 30 ° C to 60 ° C. As the heating means 29, one having an arbitrary configuration can be adopted. For example, the heating means 29 includes a heat exchanger in which a plurality of alkaline water flow paths are formed in a metal block, and a heater for heating the heat exchanger. While heating the metal block, it is possible to adopt a configuration in which alkaline water is circulated through the flow path and the alkaline water is heated to a set temperature. The heating means 29 is preferably provided in order to improve the detergency of alkaline water, but those omitted are also within the scope of the present invention.

Next, the alkaline water supply device 30 that supplies alkaline water will be described.
As shown in FIG. 2, the alkaline water supply device 30 includes soft water generating means 31, alkaline water generating means 32, alkaline water pressure tank 33, and neutral water pressure tank 34. In this embodiment, alkaline water is generated from tap water and supplied to the cleaning apparatus main body 11. However, commercially available alkaline water can be used as it is as a cleaning liquid.

  The soft water generating means 31 has a well-known configuration for generating soft water with an ion exchange resin, and for example, SS-04E manufactured by Samsung can be suitably used.

  The alkaline water generating means 32 has a known configuration in which alkaline water is generated by electrolyzing water to increase hydroxide ions (OH) on the cathode side. For example, δ1500K manufactured by Amano Corporation is suitable. Can be used for Alkaline water has different detergency depending on its pH. If the pH is high, the cleaning power tends to be improved. However, if the pH exceeds 12, the metal plate 1 and the solder 5 may be corroded. On the other hand, when the pH is lower than 10.5, a long time of washing is required to completely remove the solder 5 and the flux 4, which is not preferable because a large amount of alkaline water is required. For this reason, the pH of the alkaline water is preferably in the range of 10.5 to 12.0, and particularly preferably in the range of 11.2 to 11.5. There are various bases used for alkaline water, such as caustic soda and potassium carbonate, but the type of base is not particularly limited as long as the pH is within the above-mentioned range.

Next, a cleaning method using the cleaning apparatus 10 will be described with reference to FIG.
First, in order to generate alkaline water by the alkaline water supply device 30, tap water is supplied to the soft water generating means 31, and the soft water generating means 31 generates soft water. Specifically, it produces 1.9 liters of soft water per minute. A portion of the soft water generated by the soft water generating means 31 is used as soft water for generating alkaline water, and the rest is supplied to a neutral water pressurizing tank 34. As will be described later, the metal plate 1 with alkaline water is used. It will be used as rinse water after washing.

  Next, the soft water generated by the soft water generating means 31 is supplied to the alkaline water generating means 32, and the alkaline water is generated by the alkaline water generating means 32. Specifically, 1.5 liters of alkaline water and 0.4 liters of neutral water are generated from 1.9 liters of soft water. Potassium carbonate is used for the production of alkaline water. The generated alkaline water is sequentially supplied to the alkaline water pressurization tank 33 and stored in the alkaline water pressurization tank 33 by a set amount equal to or more than the amount necessary for one cleaning. In addition, since neutral water is also produced | generated simultaneously with the production | generation of alkaline water, this neutral water can also be supplied to the neutral water pressurization tank 34 with soft water.

  Next, in order to wash the metal plate 1 with the washing apparatus main body 11, alkaline water is pressurized and supplied from the alkaline water pressurization tank 33 to the heating means 29 by compressed air from the compressor 27, and the alkaline water is supplied at 30 ° C. After heating to a set temperature of ˜60 ° C., this is supplied to the alkaline water injection nozzle 14, and the compressed air from the compressor 27 is supplied to the alkaline water injection nozzle 14. And compressed air are mixed to make the alkaline water fine, and the alkaline water injection nozzle 14 is moved to the metal plate 1 by the moving means while spraying the finely divided alkaline water from the injection port 22 toward the metal plate 1. Along the X axis direction and the Y axis direction, and the solder 5 attached to the metal plate 1 by the fine particles of alkaline water It will wash away Lux 4.

  Specifically, the following rough cleaning and finish cleaning are sequentially performed to clean the metal plate 1.

  In the rough cleaning, first, as shown in FIG. 7, the alkaline water spray nozzle 14 is moved to the lower end of the left edge of the formation range 2 </ b> A of the print pattern 2 by the moving means. Next, the alkaline water injection nozzle 14 is moved substantially horizontally from the left edge to the right edge of the formation range 2A while spraying fine particles of alkaline water onto the metal plate 1 from the alkaline water injection nozzle 14, and then the alkaline water The alkaline water injection nozzle 14 is moved one step upward so that the water spraying range partially overlaps the upper and lower sides, and then the alkaline water injection nozzle 14 is reversed from the right edge to the left edge of the formation range 2A. The operation of moving the alkaline water spray nozzle 14 upward by one stage after being moved substantially horizontally is repeated to wash the entire formation range 2A of the print pattern 2 in order from the lower side. The formation range 2A of the print pattern 2 is set in advance for each metal plate 1 so that all the print patterns 2 formed on the metal plate 1 are included. The rough cleaning can also be performed from the lower end of the right edge of the formation range 2A of the print pattern 2.

  In the finish cleaning, first, as shown in FIG. 8, the alkaline water injection nozzle 14 is moved to the upper end of the left edge of the metal plate 1 by the moving means. Next, the alkaline water injection nozzle 14 is moved substantially horizontally from the left side edge to the right side edge of the metal plate 1 while spraying fine particles of alkaline water on the metal plate 1 from the alkaline water injection nozzle 14, and then the alkaline water The alkaline water injection nozzle 14 is moved downward by one stage so that the water spraying range partially overlaps the upper and lower sides, and then the alkaline water injection nozzle 14 is moved from the right edge of the metal plate 1 to the left edge. Then, the entire surface of the metal plate 1 is washed in order from the upper side by repeating the operation of moving the alkaline water spray nozzle 14 downward by one stage after moving the plate almost horizontally. However, since the reinforcing frame 13 is provided on the outer edge portion of the metal plate 1, the portion exposed to the inside of the reinforcing frame 13 in the metal plate 1 is washed. The finish cleaning can also be performed from the upper end of the right edge of the metal plate 1.

  In this cleaning method, the entire formation range 2A of the printed pattern 2 is cleaned in order from the lower side by rough cleaning, so that the cream solder adhering to the metal plate 1 flows downward along the metal plate 1 It is possible to prevent solidification by absorbing the alkaline water after the treatment, and to prevent poor cleaning due to solidification of the cream solder. Moreover, in this rough cleaning, only the formation range 2A of the printing pattern 2 is cleaned, so that the cleaning processing time can be greatly shortened as compared with the case where the entire surface of the metal plate 1 is cleaned. In addition, since the entire surface of the metal plate 1 is sequentially cleaned from the upper side after the rough cleaning by the finish cleaning, even when the cream solder is reattached in the rough cleaning, it can be cleaned cleanly. Furthermore, since alkaline water has the effect of saponifying and dispersing the oil, the flux 4 on the surface of the metal plate 1 can also be removed. In addition, alkaline water has a property that is easily refined compared to ion-exchanged water, and the particles of the refined alkaline water can easily pass through the printed pattern 2. The solder 5 can be removed with the pressure energy. Thereby, the flux 4 adhering to the metal plate 1, the flux 4 and the solder 5 in the printed pattern 2 can be removed cleanly.

  After the metal plate 1 is washed in this way, the neutral water stored in the neutral water pressurizing tank 34 is sprayed from the neutral water injection nozzle 28 toward the front and back surfaces of the metal plate 1, and the alkali attached to the metal plate 1. Water is washed away with neutral water, the metal plate 1 is dried, and the cleaning of the metal plate 1 is completed. The drained liquid after washing is collected in a drain tank (not shown) installed at the bottom of the housing 12 and drained after removing the solder 5 through a filter. At least one alkaline water pressure tank 33 can be provided. For example, two alkaline water pressure tanks 33 are provided, and the metal plate 1 is washed with alkaline water in one alkaline water pressure tank 33. During the washing of the metal plate 1 with the neutral water in the neutral water pressure tank 34 and the drying of the metal plate 1, the alkaline water generating means 32 is applied to the other alkaline water pressure tank 33. In order to reduce the dead time, it is preferable to store the alkaline water generated in step (b).

Next, a cleaning test of the metal plate 1 performed to verify the effect of the cleaning method of the present invention will be described.
The used metal plate 1 is a so-called M size substrate of 330 mm × 250 mm, and the pattern is for a QFP (Quad Flat Package) having a width of 0.14 mm. In the test, cream solder was applied to the metal plate 1 and it was confirmed whether or not the cream pattern solder was filled in the entire hole 3 of the printed pattern 2, and then 2 of ion exchange water (pH 6 to pH 7) and alkaline water (pH 11.2). Washing was performed using various types of cleaning solutions, and the results were compared.

  FIG. 9 shows a pattern before cleaning, in which flux 4 and solder 5 are attached to the hole 3. FIG. 10 shows the result of washing with ion-exchanged water, and FIG. 11 shows the result of washing with alkaline water. As is clear from comparison between FIGS. 10 and 11, in the cleaning using ion exchange water, the solder 5 and the flux 4 remain not only in the printed pattern 2 but also on the surface of the metal plate 1 around the pattern without being removed. On the other hand, in the cleaning using alkaline water, the solder 5 and the flux 4 in the printed pattern 2 and the surface of the metal plate 1 were completely removed, and the metal plate 1 was not damaged at all. The time required for washing was 46 minutes for ion-exchanged water, but 26 minutes for alkaline water, which has a higher washing ability than when ion-exchanged water is used with a washing time of about 60%. It could be confirmed.

  Next, another embodiment in which the configuration of the alkaline water supply device 30 is partially changed will be described. The same members as those in the above embodiment are given the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 12, this alkaline water supply device 40 supplies alkaline water composed of alkaline electrolyzed water as a cleaning liquid to the cleaning device main body 11, and stores water that stores neutral water with a salt concentration set to a constant concentration. Supplied from the tank 41, an alkaline water generator 42 for generating alkaline water composed of alkaline electrolyzed water and strongly acidic water as a by-product using neutral water in the water storage tank 41, and the alkaline water generator 42. A neutralization tank 43 that neutralizes by mixing alkaline water after used as a cleaning liquid in the cleaning apparatus main body 11 and strongly acidic water generated by the alkaline water generator 42 is provided in the neutralization tank 43. The generated neutral water is returned to the water storage tank 41, and the alkaline water after being used as a cleaning liquid is reused as neutral water.

  In the water storage tank 41, for example, 100 liters of neutral water having a salt concentration of 0.05 to 0.2% is stored. When the salt concentration is less than 0.05%, the pH of the alkaline water produced by the alkaline water generator 42 cannot be sufficiently increased. Since it becomes easy to generate | occur | produce rust etc. in the alkaline water supply apparatus 40, it is preferable to set to 0.05 to 0.2%. An aeration pipe 44 is provided in the bottom of the water storage tank 41, and a pump P4 is connected to the aeration pipe 44. Neutral water in the water storage tank 41 is agitated by bubbles discharged from the aeration pipe 44. The salinity is uniform.

  The water storage tank 41 is provided with a level sensor (not shown) that measures the amount of stored neutral water, and a water supply tank 45 is connected via a pump P1 and a water softener 46. When the amount of stored natural water drops to the lower limit level, the water in the water supply tank 45 is automatically supplied to the water storage tank 41 through the water softener 46 to the set level. That is, the neutral water of the water storage tank 41 is reduced by evaporation or wiping at the time of cleaning, and the reduced neutral water is automatically replenished. When water is supplied from the water supply tank 45 to the water storage tank 41, the salinity of neutral water in the water storage tank 41 decreases. Therefore, the water supply tank 45 has the same salinity as the neutral water of the water storage tank 41. The amount of water supplied to the storage tank 41 from the water supply tank 45 by supplying water, measuring the salinity concentration of the storage tank 41 periodically, adjusting the salt concentration of neutral water in the storage tank 41 manually The sodium chloride corresponding to the water tank 41 is automatically supplied to the water storage tank 41 so that the salt concentration of the water storage tank 41 is kept uniform. However, the water supply tank 45 and the pump P1 may be omitted and the tap water may be directly supplied to the water softener 46.

  An alkaline water generator 42 is connected to the water storage tank 41 via a pump P2, a quaternary filter F4 and a valve SV1, and neutral water in the water storage tank 41 passes through the quaternary filter F4, for example, a diameter of 0.5 μm to 1 After the oil and dust of 0.0 μm are removed, the alkaline water generator 42 is supplied. A part of the neutral water purified by the quaternary filter F4 is supplied to the neutral water pressurizing tank 34 through the valve SV2. Then, by supplying compressed air from the compressor 27 to the neutral water pressurization tank 34, the neutral water in the neutral water pressurization tank 34 is pressurized and supplied to the neutral water injection nozzle 28, and the neutral water injection is performed. Neutral water is sprayed from the nozzle 28 onto both the front and back surfaces of the metal plate 1 so that the alkaline water adhering to the metal plate 1 can be washed away with the neutral water.

  The alkaline water generator 42 has a well-known configuration for electrolyzing water using sodium chloride as an electrolysis aid to generate alkaline water composed of alkaline electrolyzed water and strong acid water as a by-product thereof. A techno super 502 manufactured by the company can be preferably used. When the pH of the alkaline water is set to a high value, the detergency is improved. However, when the pH exceeds 12, the metal plate 1 and the solder 5 may be corroded, and when the pH is lower than 10.5, the detergency is reduced. In this case, the cleaning time becomes long or a large amount of alkaline water is required. Therefore, it is desirable to set the pressure within the range of 10.5 to 12.0, and particularly within the range of 11.2 to 11.5. Is desirable. Moreover, as strong acid water, the thing of pH 2.3-2.7 is produced | generated only about the same quantity as alkaline water.

  The alkaline water generator 42 is connected to the heating means 29 of the cleaning apparatus body 11 via the alkaline water pressure tank 33, and the alkaline water generated by the alkaline water generator 42 is sequentially supplied to the alkaline water pressure tank 33. Thus, water is stored in the alkaline water pressure tank 33 by a set amount that is equal to or more than the amount necessary for one cleaning. When the metal plate 1 is washed, the alkaline water is pressurized and supplied from the alkaline water pressurization tank 33 to the heating means 29 by the compressed air from the compressor 27 in the same manner as in the above embodiment. Is heated to a set temperature of 30 ° C. to 60 ° C. and then supplied to the alkaline water injection nozzle 14, and compressed air from the compressor 27 is supplied to the alkaline water injection nozzle 14. Then, alkaline water and compressed air are mixed to make the alkaline water fine, and the alkaline water injection nozzle 14 is moved to the metal by the moving means while spraying the finely divided alkaline water from the injection port 22 toward the metal plate 1. The metal plate 1 was sequentially moved along the plate 1 in the X-axis direction and the Y-axis direction, and adhered to the metal plate 1 by the fine particles of alkaline water. It will wash away fields 5 and flux 4. The specific cleaning method for the metal plate 1 is to perform the rough cleaning and the final cleaning as in the above-described embodiment. Finally, the neutral water stored in the neutral water pressure tank 34 is washed. Is sprayed from the neutral water injection nozzle 28 toward the front and back surfaces of the metal plate 1, the alkaline water adhering to the metal plate 1 is washed away with neutral water, the metal plate 1 is dried, and the metal plate 1 is washed. Will be completed. Further, at least one alkaline water pressure tank 33 can be provided. For example, two alkaline water pressure tanks 33 are provided, and the metal plate 1 is washed with alkaline water in one alkaline water pressure tank 33. During the washing of the metal plate 1 with the neutral water in the neutral water pressurized tank 34 and the drying of the metal plate 1, the alkaline water generator 42 for the other alkaline water pressurized tank 33 is used. In order to reduce the dead time, it is preferable to store the alkaline water generated in step (b).

  On the other hand, the alkaline water and the neutral water after being used for cleaning the metal plate 1 are supplied to the neutralization tank 43 after the solder in the alkaline water is removed through the primary filter F1, and also in the alkaline water generator 42. The produced strong acid water is supplied as it is into the neutralization tank 43, and the alkaline water and the strong acid water are stirred in the neutralization tank 43 by the air supplied from the pump P4 to the aeration pipe 47. To be summed. By this neutralization, neutral water having a pH of 6 to 8 and a salt concentration substantially equal to the neutral water of the water storage tank 41 is generated in the neutralization tank 43. At the beginning of the operation of the cleaning apparatus 10, a certain amount of alkaline water is sequentially stored in the alkaline water pressurization tank 33, and only the strongly acidic water is stored in the neutralization tank 43. For this reason, when the alkaline water pressurization tank 33 and the neutralization tank 43 are empty and the cleaning apparatus 10 is operated, the alkaline water pressurization of the strongly acidic water generated by the alkaline water generator 42 is performed. The same amount of strongly acidic water as the alkaline water stored in the tank 33 is discharged to the outside of the cleaning device 10 without being charged into the neutralization tank 43, and the same amount of alkaline water and strong acid water is supplied into the neutralization tank 43. Will be adjusted to be.

  The neutralization tank 43 is connected to the water storage tank 41 through the pump P3, the secondary filter F2, and the tertiary filter F3, and the neutral water neutralized in the neutralization tank 43 is, for example, the diameter by the secondary filter F2. After the oil and dust of 0.5 μm or more are removed, the tertiary filter F3 removes the metal hydroxide having a diameter of, for example, 0.35 μm or more, and the oil of 0.5 μm or more is removed. 41 is returned. When neutral water in the water storage tank 41 is contaminated, the valve HV is opened, and the neutral water in the water storage tank 41 is filtered by the fourth filter F4 and then discharged out of the cleaning device 10. become. Further, the positions where the filters F1 to F4 are provided can be appropriately changed in consideration of the load on the pump and the like.

  In this alkaline water supply apparatus 40, after using the alkaline water produced | generated from neutral water by the washing | cleaning of the metal plate 1, after using it by this washing | cleaning using the strong acidic water produced | generated as a by-product at the time of alkaline water production | generation Since alkaline water can be generated by neutralizing alkaline water and reusing neutral water obtained by neutralization, it is not necessary to discharge alkaline water after washing out of the washing apparatus 10 over a long period of time. In this case, it can be discharged as neutral water, so an environmentally friendly cleaning device can be realized.

Perspective view of the main part of the cleaning device body Schematic illustration of cleaning equipment Perspective view of spray nozzle Exploded perspective view of spray nozzle V-V cross-sectional view of FIG. Sectional view taken along line VI-VI in Fig. 3 Illustration of rough cleaning method Illustration of cleaning method for finish cleaning Enlarged view of metal plate printing pattern before cleaning Enlarged view of metal plate printing pattern after cleaning with ion exchange water Enlarged view of metal plate printing pattern after washing with alkaline water Schematic explanatory diagram of a cleaning device using another alkaline water generator

DESCRIPTION OF SYMBOLS 1 Metal plate 2 Print pattern 2A formation range 3 Hole 4 Flux 5 Solder 10 Metal plate washing | cleaning apparatus 11 Cleaning apparatus main body 12 Housing 13 Reinforcement frame 14 Alkaline water injection nozzle 15 Flow path 15a Branch path 16 Flow path 17 Nozzle body 18 Nozzle cap 19 Retainer 20 Supply pipe 21 Plug 22 Injection port 23 Partition 24 First space 25 Second space 26 Throttle gap 27 Compressor 28 Neutral water injection nozzle 29 Heating means 30 Alkaline water supply device 31 Soft water generating means 32 Alkaline water generating means 33 Alkaline water Pressurized tank 34 Neutral water pressurized tank 40 Alkaline water supply device 41 Water storage tank 42 Alkaline water generator 43 Neutralization tank 44 Aeration pipe 45 Water supply tank 46 Water softener 47 Aeration pipe F1 Primary filter F2 Next filter F3 3-order filter F4 4 order filter HV valve SV1 valve SV2 valve P1 pump P2 Pump P3 Pump P4 pump

Claims (12)

A method for cleaning a metal plate used for printing cream solder on a printed wiring board,
While the metal plate is supported at a certain angle with respect to the horizontal direction, the spray nozzle is reciprocated in the horizontal direction while spraying an aqueous cleaning liquid from the spray nozzle toward the metal plate. Roughly wash the metal plate in order,
A metal plate cleaning method characterized by that.   The metal plate cleaning method according to claim 1, wherein after the rough cleaning, the metal plate is finished and cleaned in order from the upper side by reciprocating the injection nozzle in the horizontal direction while spraying a cleaning liquid from the injection nozzle toward the metal plate. .   In the rough cleaning, a cleaning liquid is sequentially sprayed on the formation range of the printed pattern of the metal plate to perform the rough cleaning, and in the finishing cleaning, the cleaning liquid is sequentially sprayed on the entire surface of the metal plate to perform the final cleaning. Item 3. A method for cleaning a metal plate according to Item 2.   The method for cleaning a metal plate according to any one of claims 1 to 3, wherein the cleaning liquid is supplied to the spray nozzle in a state heated to 30 ° C to 60 ° C.   Alkaline water is used as the cleaning liquid, and the cleaning liquid and compressed air are mixed in the injection nozzle, and the cleaning liquid is atomized and sprayed at high speed from the injection nozzle toward the metal plate. The metal plate cleaning method according to any one of claims 1 to 4, wherein the metal plate is cleaned.   The metal plate cleaning method according to claim 5, wherein a hydrogen ion index of the cleaning liquid is set to pH = 10.5 to 12.0.   The metal plate cleaning method according to claim 5 or 6, wherein a volume ratio of the compressed air and the cleaning liquid is set to 500: 1 to 700: 1.   The metal plate according to claim 1, wherein jet nozzles are respectively provided on both sides of the metal plate, and the metal plate is cleaned while spraying a cleaning liquid on both sides of the metal plate from both jet nozzles. Cleaning method.   The metal plate cleaning method according to claim 8, wherein spraying positions of the cleaning liquid by the two spray nozzles are shifted.   The metal plate washing | cleaning method of any one of Claims 1-9 which set the distance between the front-end | tip part of the said injection nozzle and a metal plate to 3-8 mm.   The injection nozzle includes a nozzle body having a compressed air flow path and a cleaning liquid flow path, and a nozzle cap that is detachably attached to the tip of the nozzle body. A partition wall protruding toward the injection port is formed at the tip of the nozzle body, and this partition allows a space between the nozzle body and the nozzle cap to be formed in a first space on both sides of the partition wall and a second space on the tip side of the partition wall. The space is divided into three spaces, and a pair of the first space and the second space are communicated with each other through a constriction gap formed between the tip of the partition wall and the nozzle cap, and the flow path of the compressed air is paired with the first space. Each was opened in one space, and the cleaning liquid flow passage was opened from the tip of the partition wall to the second space, and the cleaning liquid and the compressed air were mixed in the second space to make the cleaning liquid finer. Claim 1 The method of cleaning metal plate as claimed in any one of claims 10. The metal plate cleaning method according to claim 11, wherein the injection port is formed in a long hole shape having an aspect ratio of 40 or more.

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