Patent Publication Number: US-2017368628-A1

Title: Spray apparatus and method of ejecting mist using spray apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority from Japanese Patent Application No. 2016-125009 filed on Jun. 23, 2016. 
     TECHNICAL FIELD 
     The disclosure relates to a spray apparatus and a method of ejecting mist by using the spray apparatus. 
     RELATED ART 
     In the related art, a soldering has been widely used as a method of bonding metal components such as lands and through-holes formed on a surface of a printed board and lead lines of mounted components such as a semiconductor device and a capacitor mounted on the board so that energization can be enabled. As a pre-process of the soldering, it is necessary to apply a flux solution. In general, the flux solution is a liquid in which a rosin-based or acryl-based resin, an alcohol or aromatic solvent and an activator are mixed. The flux solution is uniformly applied to places in advance, at which the metal components and the mounted components are to be bonded by the soldering, on the printed board, so that an oxide layer formed on the target places becomes reduced or removed. As a result, a clean adhesion surface is formed at the target places, wettability between the soldering and the metal surface is improved and the bonding becomes strong. 
     In order to uniformly apply the flux solution to the applying target, a method of ejecting the flux solution in a mist form by using a spray has been widely used. In general, the spray is configured to eject compressed liquid from an ejection port (orifice) of a nozzle tip and to form the liquid into fine particles, thereby ejecting the mist. 
     Meanwhile, in order to eject the liquid in the mist form, a pressure (ejection pressure) by which the liquid is to be introduced into the nozzle should be a predetermined pressure or higher. If the ejection pressure is lower than the predetermined pressure, the liquid is ejected from the nozzle without being formed into the mist. A flying distance (reaching distance) and a spreading angle (ejection angle) of the mist to be ejected from the ejection port depend on the ejection pressure, so that they increase as the ejection pressure increases. Therefore, in general, when ejecting the flux by using the spray, it is difficult to make the reaching distance and ejection angle of the flux solution to be ejected smaller than predetermined values. 
     However, when ejecting and applying the flux to the through-holes of the board by using the spray, the reaching distance becomes long, so that the flux may pass through the through-holes, which are the applying target, and may be unintentionally attached to the components on the board. Also, the ejection angle becomes large, so that the flux may be unintentionally attached to the mounted components, which are not the applying target. In this case, in a rotary encoder to be used for a dial for volume adjustment of an audio product, for example, the flux may be introduced into a component, so that a malfunction may be caused. In the meantime, as a method of feebly applying a small amount of flux, a method of using an ultrasonic flux spray apparatus has been known. However, the corresponding apparatus has a complicated structure and is expensive. 
     Therefore, as a method of uniformly applying a necessary amount of flux into the through-holes of the printed board without using the spray, a method of using a flux applying apparatus of Patent Document 1 has been known, for example. The flux applying apparatus disclosed in Patent Document 1 is configured to jet a flux reserved in a nozzle from an upward opening and to bring a liquid surface of the jetted flux into contact with the board, thereby applying the flux to the board. 
     Patent Document 1: Japanese Patent Application Publication No. 2005-262247A 
     According to the flux applying apparatus disclosed in Patent Document 1, it is possible to apply the flux to the through-holes by a suction effect of the surface tension without introducing the flux into the component. However, with the flux applying apparatus disclosed in Patent Document 1, it is not possible to control an attachment amount of the flux into the through-holes and the flux is attached beyond necessity. For this reason, a surplus flux accumulated in the through-holes is pushed by the soldering upon the soldering, so that the flux is likely to be introduced into the component. Also, when drying and removing the surplus flux accumulated in the through-holes, it takes time until the drying is completed, which may lower the productivity. Also, the flux applying apparatus has demerits that a structure thereof is complex and a failure risk is high. 
     SUMMARY 
     It is therefore an object of the present invention to provide a spray technology capable of reducing an amount and a flow strength of mist to be ejected and favorably spraying the mist to an ejection target. 
     According to an aspect of the embodiments of the present invention there is provided a spray apparatus comprising: a first nozzle configured to eject mist; and a second nozzle provided around the first nozzle, wherein the second nozzle is configured to suck a part of the mist ejected from the first nozzle and to eject a remnant of the mist to an ejection target. 
     According to the disclosure, the first nozzle configured to eject the mist is provided with the second nozzle, and a part of the mist ejected from the first nozzle is sucked by the second nozzle. For this reason, a flow rate and an ejection pressure of the mist to be ejected to the ejection target are reduced. 
     According to the disclosure, it is possible to reduce the amount and flow strength of the mist to be ejected by the structure simpler than the related art and to spray the flux to a part or a component, for which the spray apparatus of the related art cannot be used. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detailed based on the following figures, wherein: 
         FIG. 1  illustrates an overall flux spray apparatus in accordance with a first illustrative embodiment; 
         FIG. 2  illustrates a nozzle device in accordance with the first illustrative embodiment; 
         FIG. 3  illustrates the nozzle device when a flux is applied to a target by using a flux spray apparatus of the related art; 
         FIG. 4  illustrates the nozzle device when the flux is applied to the target by using the flux spray apparatus of the first illustrative embodiment; 
         FIG. 5  depicts a nozzle device in a flux spray apparatus in accordance with a second illustrative embodiment, in which (a) is a perspective view of the nozzle device and (b) illustrates the nozzle device when the flux is applied to the target; and 
         FIG. 6  is a graph depicting a comparison test result of flux spray apparatuses of an embodiment and a conventional example. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, favorable illustrative embodiments of the disclosure will be described with reference to the drawings. The illustrative embodiments to be described later are just examples for implementing the disclosure, and the disclosure is not limited to the illustrative embodiments. 
     First Illustrative Embodiment 
     An outline of a flux spray apparatus  100  in accordance with a first illustrative embodiment is described with reference to  FIG. 1 .  FIG. 1  depicts the overall flux spray apparatus  100  in accordance with the first illustrative embodiment. In  FIG. 1 , a direction from left towards right is an X direction, a direction from a front side of the drawing sheet towards an inner side thereof is a Y direction, and a direction from below towards above is a Z direction. A −Z direction coincides with a perpendicular direction. As shown in  FIG. 1 , the flux spray apparatus  100  includes a nozzle device  10 , a flux solution supply device  20 , a negative pressure pipe  30  including a first negative pressure pipe  31  and a second negative pressure pipe  32 , a flux solution collection device  40 , a negative pressure generation device  50 , a negative pressure control device  60 , a base  70 , and a movement device  80 . The nozzle device  10  is set on the base  70 , and the base  70  is coupled to the movement device  80  with the nozzle device  10  being set thereon. The nozzle device  10  is configured to communicate with the flux solution supply device  20  via the base  70 . Also, the nozzle device  10  is configured to communicate with the flux solution collection device  40  via the second negative pressure pipe  32 . The flux solution collection device  40  is further configured to communicate with the negative pressure generation device  50  via the first negative pressure pipe  31 . The negative pressure generation device  50  is connected with the negative pressure control device  60 . 
     In the first illustrative embodiment, the flux spray apparatus  100  is configured to eject a mist flux M to an outside of the flux spray apparatus  100 . When applying the mist flux M to a printed board  200  by using the flux spray apparatus  100 , the printed board  200 , which is an applying target of the flux, is arranged in the Z direction of the flux spray apparatus  100 . That is, the nozzle device  10  is set on the base  70  so that the mist flux M is to be ejected in the Z direction. The base  70  is coupled with the movement device  80 , and the nozzle device  10  is configured to be freely moveable on a horizontal plane of the base  70 . That is, the nozzle device  10  is configured to be freely moveable on an XY plane. 
     The printed board  200  is arranged so that a lower surface thereof faces towards the -Z direction, i.e., a perpendicular direction, and is carried in the X direction by a conveyor apparatus  300  with both ends being supported. Then, an operation of applying the flux to the printed board  200  is performed at a predetermined position by the nozzle device  10 . The printed board  200  has a plurality of through-holes  210 , which are an applying target of the flux. Also, an upper surface of the printed board  200  is provided with an upper surface component  220 , which is not an applying target of the flux, and a lower surface of the printed board  200  is provided with a lower surface component  230 , which is not an applying target of the flux. 
     In the flux spray apparatus  100 , a driving timing of the movement device  80 , an ejection timing of the mist flux M and the like are beforehand programmed in a spray control unit (not shown). Therefore, it is possible to apply the mist flux M from the lower surface of the printed board  200  to an applying target located in a desired region. When the applying of the mist flux M is over, the printed board  200  is sent to a next process and a mounted component is soldered to a part to which the mist flux M has been applied. 
     Although described in detail later, the flux spray apparatus  100  of the first illustrative embodiment is configured to primarily eject the mist flux M into the nozzle device  10  by mixing a liquid flux L and air supplied to the nozzle device  10  from the flux solution supply device  20 . The flux spray apparatus  100  is further configured to generate a negative pressure in the nozzle device  10  by the negative pressure generation device  50 , to suck a part of the primarily ejected mist flux M from the inside of the nozzle device  10 , and to secondarily eject the remnant from the nozzle device  10  to the applying target. As a result, it is possible to reduce an ejection amount of the mist flux M to be secondarily ejected to the applying target, as compared to an ejection amount of the mist flux M to be primarily ejected into the nozzle device  10 . Also, the flux spray apparatus  100  can lower an ejection pressure of the mist flux M to be secondarily ejected by enabling the negative pressure to act in the nozzle device  10 . As a result, it is possible to shorten a reaching distance of the mist flux M to be ejected to the applying target and to make an ejection angle smaller. 
     The flux spray apparatus  100  of the first illustrative embodiment can adjust a flow rate and the ejection pressure of the mist flux M by adjusting the negative pressure, which is to be generated by the negative pressure generation device  50 . 
     In the specification, the term “primary ejection” indicates an ejection in the nozzle device  10  and the term “secondary ejection” indicates an ejection to the outside of the nozzle device  10 . The term “flow rate” indicates an amount of fluid to flow per unit time. The term “ejection amount” indicates an amount of the fluid to be ejected. The term “ejection pressure” is an index indicative of flow strength of the fluid to be ejected, and indicates a pressure of the fluid in the nozzle upon ejection of the fluid from an ejection port of the spray nozzle. The term “reaching distance” is a flying distance of the fluid to be ejected, and indicates a straight line distance up to the farthest position, which the fluid can reach from the ejection port, on a central axis of the ejection port. The term “ejection angle” indicates a spreading angle of the fluid ejected from the spray nozzle. Also, the term “negative pressure” indicates is a pressure of the fluid in any space and indicates a pressure lower than an outside of the space. The negative pressure indicates a negative value. The larger an absolute value of the negative pressure, a pressure is lower. In the below, the respective configurations are described with reference to  FIG. 1 . 
     The flux solution supply device  20  is a device configured to supply the liquid flux L to the nozzle device  10  and to apply an ejection pressure, which is necessary to generate the mist flux M from the liquid flux L, to the mist flux M. The flux solution supply device  20  has an air compressor embedded therein, and is configured to supply the air compressed together with the compressed liquid flux L to the nozzle device  10 . The compressed liquid flux L and the compressed air are mixed by the nozzle device  10 , so that the mist flux M is obtained. In the first illustrative embodiment, the configuration of the flux solution supply device  20  is not particularly limited and can be appropriately changed. 
     The negative pressure generation device  50  is a device configured to operate all the time or temporarily, thereby generating a negative pressure in the nozzle device  10 . The negative pressure generation device  50  is configured to communicate with the inside of the nozzle device  10  via the negative pressure pipe  30  and the flux solution collection device  40 . For this reason, when the negative pressure generation device  50  is operated, the negative pressure acts in the nozzle device  10  and a part of the mist flux M is sucked from the inside of the nozzle device  10 . The negative pressure generation device  50  can adjust the negative pressure acting in the nozzle device  10  within a predetermined range. In order to operate the negative pressure generation device  50 , an operator may manually operate the same or control the same in a program manner by the negative pressure control device  60 . As the negative pressure generation device  50 , a pump may be exemplified. The negative pressure generation device  50  corresponds to the suction device of the disclosure. 
     The flux solution collection device  40  is a device configured to separate the mist flux M sucked from the nozzle device  10  into the liquid flux L and the air and to reserve therein the separated liquid flux L. The flux solution collection device  40  is configured to communicate with the negative pressure pipe  30  configured to communicate the nozzle device  10  and the negative pressure generation device  50  each other. More specifically, the flux solution collection device  40  is configured to communicate with the negative pressure generation device  50  via the first negative pressure pipe  31  and to communicate with the nozzle device  10  via the second negative pressure pipe  32 . The mist flux M sucked from the inside of the nozzle device  10  as the negative pressure generation device  50  operates is collected to the flux solution collection device  40  via the second negative pressure pipe  32 . The mist flux M collected to the flux solution collection device  40  is separated into the liquid flux L and the air, and the liquid flux L is reserved in the flux solution collection device  40 . As a method of separating the liquid flux L from the mist flux M, a method of using a mist separator may be used, for example. 
     Subsequently, the nozzle device  10  provided for the flux spray apparatus  100  is described with reference to  FIG. 2 .  FIG. 2  depicts the nozzle device  10  of the first illustrative embodiment. 
     As shown in  FIG. 2 , the nozzle device  10  of the first illustrative embodiment has a first nozzle  1  and a second nozzle  2  externally fitted to the first nozzle  1 . The first nozzle  1  is a nozzle configured to communicate with the flux solution supply device  20  via the base  70 , to generate the mist flux M and to primarily eject the mist flux M into the nozzle device  10 . Also, the second nozzle  2  is a nozzle configured to suck/discharge a part of the mist flux M primarily ejected by the first nozzle  1  from the inside of the nozzle device  10  and to secondarily eject the remaining mist flux M to an exterior air, thereby ejecting the mist flux M to the applying target. 
     The first nozzle  1  is generally a nozzle for spray to be used for applying the flux. That is, the first nozzle  1  has a straight cylinder part  12  connected in communication with to the base  70 , a tapered part  13  coaxially connected with the straight cylinder part  12  and a first ejection port  11  having a circular shape and provided at a tip of the tapered part  13 . The straight cylinder part  12 , the tapered part  13  and the first ejection port  11  are configured to communicate each other. The straight cylinder part  12  has a cylindrical shape having a predetermined diameter and the tapered part  13  has a substantially conical shape of which an outer diameter gradually decreases towards the first ejection port  11 . 
     The liquid flux L and the air supplied with being compressed from the flux solution supply device  20  are sent from the straight cylinder part  12  via the base  70 , are mixed while passing an inside of the tapered part  13  and are ejected with a predetermined ejection pressure P, so that the mist flux M of a flow rate F is generated. The mist flux M is primarily ejected from the first ejection port  11  into the nozzle device  10 . In the first illustrative embodiment, the structure of the first nozzle  1  is not particularly limited and can be appropriately changed. 
     Subsequently, the second nozzle  2  is described in detail. The second nozzle  2  can be generally externally fitted to the first nozzle  1 , which is a nozzle for spray to be used for applying the flux, and is formed to be fixable to the first nozzle  1 . Therefore, the second nozzle  2  has a function as an attachment configured to be detachably mounted to the existing nozzle. As shown with a broken line in  FIG. 2 , the second nozzle  2  has a cylindrical main body part  21  having a predetermined inner diameter and different outer diameters in an axial direction, a cylindrical housing part  22  formed around the main body part, and a collar part  23 . 
     As shown with the broken line in  FIG. 2 , the main body part  21  has an ejection portion  21   a  located at one end portion-side, an introduction portion  21   b  located at the other end portion-side, and a large-diameter portion  21   c  formed between the ejection portion  21   a  and the introduction portion  21   b  and having an outer diameter greater than an outer diameter of the introduction portion  21   b.  The ejection portion  21   a,  the introduction portion  21   b  and the large-diameter portion  21   c  are formed so that central axes thereof coincide each other. A tip of the ejection portion  21   a  is provided with a second ejection port  211  configured to secondarily eject the mist flux M to the applying target, and a tip of the introduction portion  21   b  is provided with an introduction port  212  configured to introduce the mist flux M primarily ejected from the first ejection port  11  of the first nozzle  1  into the second nozzle  2 . The second ejection port  211  and the introduction port  212  have circular shapes of the same diameter, and centers of the second ejection port  211  and the introduction port  212  are located on the central axis of the main body part  21 . Also, the main body part  21  is formed with a communication path  213  configured to communicate with the second ejection port  211  and the introduction port  212  and to axially penetrate the second nozzle  2 . 
     The ejection portion  21   a  of the main body part  21  has a taper shape of which an apex is the second ejection port  211 , so as to easily remove the dripped flux ejected from the second ejection port  211 . 
     Diameters of the introduction port  212  and the communication path  213  are smaller than an outer diameter of the straight cylinder part  12  of the first nozzle  1  and greater than an outer diameter of the tip of the tapered part  13  of the first nozzle  1 . That is, the diameters of the introduction port  212  and the communication path  213  are greater than a diameter of the first ejection port  11 . Also, a peripheral edge portion of the introduction port  212  is formed with a plurality of notches  212   a  equidistantly spaced over an entire circumference in a circumferential direction. 
     A peripheral edge of an end surface of the large-diameter portion  21   c,  which is located at the introduction portion  21   b -side, is formed with the cylindrical housing part  22  coaxially with the main body part  21 . That is, an inner diameter of the housing part  22  is greater than the outer diameter of the introduction portion  21   b.  Also, the inner diameter of the housing part  22  is set to a size greater than the outer diameter of the straight cylinder part  12  of the first nozzle  1  by about a fitting tolerance so that it can be externally fitted to the first nozzle  1 . Herein, the inner diameter of the housing part  22  is preferably twice as large as the outer diameter of the introduction portion  21   b.  In the second nozzle  2  of the first illustrative embodiment, the outer diameter of the introduction portion  21   b  is 8 mm, and the inner diameter of the housing part  22  is 24 mm. 
     Also, an opening end  221 , which is an axial tip of the housing part  22 , more protrudes axially than the introduction portion  21   b  of the main body part  21 . That is, the second nozzle  2  has a double cylindrical shape of the cylindrical main body part  21  and the cylindrical housing part  22 , in which the introduction portion  21   b  of the main body part  21 , which is an inner cylindrical member, is positioned in the second nozzle  2  at an axially more inner side than the opening end  221  of the housing part  22 , which is an outer cylindrical member. 
     A sidewall of the housing part  22  is connected with the negative pressure pipe  30  configured to communicate the flux solution collection device  40  and the inside of the nozzle device  10 , and is formed with a penetrated suction port  222  through which the mist flux M is to be discharged. The suction port  222  is configured so that a suction nozzle E can be screwed therein. The negative pressure pipe  30  is connected to the suction port  222  via the suction nozzle E. 
     Also, the housing part  22  is provided with a plurality of screw holes  223  with a predetermined interval in the circumferential direction into which screws B (not shown) are to be screwed so as to fix the first nozzle  1  to the second nozzle  2 . The screw holes  223  are located at the opening end  221 -side axially closer than the suction port  222 . 
     The collar part  23  is formed to extend around the ejection portion  21   a  of the main body part  21 . The collar part  23  has a circular shape of which a section perpendicular to the central axis of the main body part  21  has a center on the axis of the main body part  21 . Also, the section of the collar part  23 , including the central axis of the main body part  21 , has a taper shape of which a width gradually decreases towards the ejection portion  21   a.  For this reason, it is possible to easily remove the flux dripped from the second ejection port  211  and the dripped flux rebounded from the printed board  200 . An outer diameter of the collar part  23  at the large-diameter portion  21   c -side is about twice as large as the outer diameter of the housing part  22 . 
     In order to assemble the nozzle device  10  of the first illustrative embodiment, the second nozzle  2  is externally fitted to the first nozzle  1  from the opening end  221  along the central axis of the communication path  213  at a state where the first ejection port  11  and the introduction port  212  are concentric with each other and face each other. 
     Since the inner diameter of the housing part  22  is greater than the outer diameter of the straight cylinder part  12  of the first nozzle  1  by the fitting tolerance, the housing part  22  does not inhibit that the straight cylinder part  12  of the first nozzle  1  is to be inserted into the second nozzle  2 . For this reason, the straight cylinder part  12  of the first nozzle  1  slides along an inner surface of the housing part  22 . As a result, the first nozzle  1  can be inserted up to a position at which the tapered part  13  contacts the introduction portion  21   b  of the second nozzle  2 . 
     Since a diameter of the introduction port  212  is formed to be smaller than the outer diameter of the straight cylinder part  12  of the first nozzle  1  and to be greater than the outer diameter of the tip of the tapered part  13 , the introduction port  212  contacts an outer surface of the tapered part  13  of the first nozzle  1 . Therefore, the first ejection port  11  of the first nozzle  1  is located in the introduction portion  21   b  of the main body part  21  of the second nozzle  2  and in the introduction port  212 . 
     At the state where the introduction port  212  of the second nozzle  2  contacts the outer surface of the tapered part  13  of the first nozzle  1 , the inner surface of the housing part  22  contacts the outer surface of the straight cylinder part  12 . At this time, the inner surface of the housing part  22  axially contacts the outer surface of the straight cylinder part  12  at the positions at which the screw holes  223  are provided and does not contact the outer surface of the straight cylinder part  12  at the position at which the suction port  222  is provided. At this state, when the screws B (not shown) are tightened from the screw holes  223 , the first nozzle  1  and the second nozzle  2  are fixed by the straight cylinder part  12  and the housing part  22 . In this way, the second nozzle  2  is externally fitted and fixed to the first nozzle  1 , so that the nozzle device  10  is assembled. 
     At this time, since the peripheral edge portion of the introduction port  212  is formed with the plurality of notches  212   a  equidistantly spaced over the entire circumference, the contact part between the introduction port  212  of the second nozzle  2  and the outer surface of the tapered part  13  of the first nozzle  1  is formed with a plurality of discharge ports  214  by a surface forming the plurality of notches  212   a  and the outer surface of the tapered part  13 . That is, the discharge ports  214  are formed in the communication path  213  in the vicinity of the first ejection port  11  of the first nozzle  1 . Also, since the plurality of notches  212   a  has the same shape, the plurality of discharge ports  214  also has the same shape. 
     Also, in the nozzle device  10 , a space A surrounded by the tapered part  13  of the first nozzle  1 , the housing part  22  of the second nozzle  2 , the introduction portion  21   b  and the large-diameter portion  21   c  is formed. Since the outer surface of the straight cylinder part  12  and the inner surface of the housing part  22  contact each other, the space A communicates with the outside of the nozzle device  10  only at the suction port  222  and the discharge ports  214 . 
     The nozzle device  10  assembled as described above is set on the base  70  so that the second ejection port  211  of the main body part  21  of the second nozzle  2  faces towards the Z direction. 
     In the below, a series of operations of applying the mist flux M to the through-holes  210  formed in the printed board  200  by using the flux spray apparatus  100  of the first illustrative embodiment are described with reference to  FIGS. 3 and 4 . 
       FIG. 3  illustrates the nozzle device  10  when the mist flux M is applied to the through-holes  210  formed in the printed board  200  by using a flux spray apparatus  100   a  of the related art, as a comparative example.  FIG. 4  illustrates the nozzle device  10  when the mist flux M is applied to the through-holes  210  formed in the printed board  200  by using the flux spray apparatus  100  of the first illustrative embodiment. 
     In order to favorably apply the mist flux M to the through-holes  210  formed in the printed board  200 , it is preferable that the mist flux M is applied to the entire inner surfaces of the through-holes  210  and the mist flux M does not pass through the through-holes  210 . That is, a reaching distance of the mist flux M to be secondarily ejected is preferably a favorable reaching distance D 0 , which is a distance from the ejection port, from which the mist flux M is to be secondarily ejected, to an upper surface of the printed board. 
     Also, in order to favorably apply the mist flux M to the through-holes  210 , it is preferable that the secondarily ejected mist flux M is applied to the through-holes  210  and is not applied to the lower surface component  230  arranged on the lower surface of the printed board  200 . That is, an ejection angle of the mist flux M to be secondarily ejected is preferably equal to or less than an ejection angle θ 0 , which is a maximum angle at which the mist flux M is to be applied to the through-holes  210  and is not to be applied to the lower surface component  230 . 
     First, a case where the flux spray apparatus  100   a  of the related art is used is described with reference to  FIG. 3 . The flux spray apparatus  100   a  of the related art is different from the flux spray apparatus  100  of the first illustrative embodiment, in that it does not have the second nozzle  2 . That is, as shown in  FIG. 3 , according to the flux spray apparatus  100   a  of the related art, the mist flux M is directly ejected from the first nozzle  1  to the applying target. For this reason, the mist flux M is directly ejected to the applying target without being collected to the flux solution collection device  40 . In the below, the description of the same configurations as the first illustrative embodiment is omitted. 
     In the flux spray apparatus  100   a,  the liquid flux L and the air supplied with being compressed from the flux solution supply device  20  are mixed in the first nozzle  1  and are then ejected with an ejection pressure equal to or higher than a predetermined ejection pressure P, so that the mist flux M of a flow rate F is made. When the ejection is performed with the ejection pressure P, the mist flux M is ejected at a predetermined ejection angle θ from the first ejection port  11  to the applying target. At this time, a reaching distance of the mist flux becomes a predetermined reaching distance D. When the ejection pressure is higher than the predetermined ejection pressure P, the reaching distance becomes longer than the predetermined reaching distance D and the ejection angle becomes greater than the predetermined ejection angle θ. Herein, in order to form the liquid flux L into the mist flux M, it is necessary to eject the mist flux M with a pressure equal to or higher than the predetermined ejection pressure P. Therefore, it is not possible to make the reaching distance shorter than the predetermined reaching distance D and the ejection angle smaller than the predetermined ejection angle θ. 
     As shown in  FIG. 3 , when the predetermined reaching distance D is longer than the favorable reaching distance D 0 , the surplus mist flux M passes through the through-holes  210 , which are the applying target, so that the surplus mist flux may be unintentionally attached to the upper surface component  220  on the printed board  200 . Also, when the predetermined ejection angle θ is greater than the favorable ejection angle θ 0 , the surplus mist flux M spread in a wider range than a region intended to be applied may be unintentionally attached to the lower surface component  230 , which is not the applying target. Also, when the flow rate F of the ejected mist flux M is high, the surplus flux may be attached to the inner surfaces of the through-holes  210 . 
     Subsequently, a case where the flux spray apparatus  100  of the first illustrative embodiment is used is described with reference to  FIG. 4 . As described above, according to the flux spray apparatus  100 , the second nozzle  2  is externally fitted to the first nozzle  1  in the nozzle device  10 , so that the space A and the plurality of discharge ports  214  are formed. In the space A, the suction port  222  is configured to communicate with the negative pressure generation device  50  via the negative pressure pipe  30  and the flux solution collection device  40 , and the discharge ports  214  are configured to communicate with the outside via the communication path  213 . 
     The flux spray apparatus  100  of the first illustrative embodiment is configured to generate the mist flux M by the first nozzle  1  and to once eject the generated mist flux M into the nozzle device  10 . More specifically, the liquid flux L supplied from the flux solution supply device  20  is mixed with the air in the first nozzle  1 , so that it becomes the mist flux M of a flow rate F 1  and is then primarily ejected from the first ejection port  11  with an ejection pressure P 1 . The flow rate F 1  is the same as the flow rate F, and the ejection pressure P 1  is the same as the predetermined ejection pressure P. As shown in  FIG. 4 , since the first ejection port  11  is located in the introduction port  212  of the second nozzle  2 , i.e., the first ejection port  11  is located in the communication path  213 , the mist flux M is primarily ejected into the communication path  213 . 
     When the negative pressure generation device  50  is operating with the mist flux M being primarily ejected into the introduction portion  21   b,  the negative pressure acts in the space A because the negative pressure generation device  50  communicates with the space A in the nozzle device  10  via the negative pressure pipe  30  and the flux solution collection device  40 . Since the space A is configured to communicate with only the communication path  213  except for the suction port  222  via the discharge ports  214 , the suction pressure acts so that the fluid in the communication path  213  is to be sucked by the negative pressure acting in the space A. As a result, as shown with an arrow B in  FIG. 4 , the suction pressure acts in the nozzle device  10  so that an exterior air is to be introduced from the second ejection port  211  and is to be discharged from the suction port  222 . 
     At this time, since the mist flux M is primarily ejected into the communication path  213  from the first ejection port  11  of the first nozzle  1 , the suction pressure acts on the mist flux M. A part of the primarily ejected mist flux M passes through the discharge ports  214  provided around the introduction portion  21   b  and is then sucked into the space A from the communication path  213 . The mist flux M sucked into the space A is discharged from the suction port  222  to the outside of the nozzle device  10 , passes through the first negative pressure pipe  31  and is then collected to the flux solution collection device  40 . The collected mist flux M is separated into the air and the liquid flux L and the liquid flux L is reserved in the flux solution collection device  40 . 
     The mist flux M, which reaches the second ejection port  211  without being sucked into the space A, of the primarily ejected mist flux M is secondarily ejected from the second ejection port  211 . The part of the mist flux M is discharged from the discharge ports, so that an amount of the mist flux M to reach the second ejection port  211  becomes smaller than an amount of the mist flux ejected from the first ejection port  11 . For this reason, a flow rate F 2  of the mist flux M to be secondarily ejected becomes less than the flow rate F 1  of the primarily ejected mist flux M. 
     Also, the suction pressure acting on the mist flux M in the communication path  213  by the negative pressure in the space A acts so that an ejection pressure of the secondary ejection is to be weakened. For this reason, an ejection pressure P 2  of the secondary ejection is lower than the ejection pressure P 1  upon the primary ejection. 
     Herein, the discharge ports  214  are formed with being equidistantly spaced over the entire circumference in the circumferential direction of the communication path  213 , and the space A communicates with the communication path  213  via all the discharge ports  214 . For this reason, the primarily ejected mist flux M is uniformly sucked from the plurality of discharge ports  214 . As a result, the mist flux M to be secondarily ejected forms a uniform spray pattern and is uniformly applied to the applying target. Also, the second nozzle  2  of the first illustrative embodiment is configured so that the inner diameter of the housing part  22  is about twice as large as the outer diameter of the introduction portion  21   b  having the discharge ports. For this reason, the mist flux M is sucked from the plurality of discharge ports  214  in a balanced manner. As a result, the mist flux M to be secondarily ejected more uniformly forms a uniform spray pattern. 
     In this way, the flux spray apparatus  100  can operate the negative pressure generation device  50 , thereby making the flow rate F 2  and ejection pressure P 2  of the mist flux M to be secondarily ejected from the second ejection port less than the flow rate F 1  and ejection pressure P 1  of the mist flux M to be primarily ejected from the first ejection port  11 . In other words, it is possible to weaken the secondary ejection, as compared to the primary ejection. That is, the flux spray apparatus  100  can generate the negative pressure in the nozzle device  10  by operating the negative pressure generation device  50 , thereby making the flow rate F 2  and ejection pressure P 2  of the mist flux M to be secondarily ejected less than the flow rate F and ejection pressure P of the mist flux M to be ejected in the flux spray apparatus  100   a  of the related art. As a result, the flux spray apparatus  100  can make the reaching distance D 1  and ejection angle θ 1  of the mist flux M to be secondarily ejected smaller than the reaching distance D and ejection angle θ of the mist flux M to be ejected in the flux spray apparatus  100   a  of the related art. 
     The flux spray apparatus  100  of the first illustrative embodiment can appropriately adjust a magnitude of the negative pressure that is to act in the space A in the nozzle device  10  by the negative pressure generation device  50 . The negative pressure may be adjusted by manually operating the negative pressure generation device  50  or program-controlling the same with the negative pressure control device  60 . When the negative pressure having a greater absolute value is enabled to act, the suction pressure to act on the mist flux M also increases and the flow rate F 2  and ejection pressure P 2  of the mist flux M to be secondarily ejected more decrease. Also, when the absolute value of the negative pressure is made to gradually decrease, the suction pressure to act on the mist flux M also decreases and the flow rate F 2  and ejection pressure P 2  of the mist flux M to be ejected increase up to the flow rate F 1  (≈the flow rate F) and ejection pressure P 1  (≈the ejection pressure P) upon the primary ejection, which are upper limits. In this way, the acting negative pressure is controlled by the negative pressure generation device  50 , so that the flow rate F 2  and the ejection pressure P 2  can be adjusted and the reaching distance D 1  and the ejection angle θ 1  can also be favorably adjusted. 
     As shown in  FIG. 4 , the negative pressure is adjusted so that the reaching distance D becomes the favorable reaching distance D 0 , and the mist flux M is secondarily ejected to the through-holes  210 , so that the mist flux M does not pass through the through-holes  210 . Thereby, it is possible to suppress the surplus flux from being unintentionally attached to the upper surface component  220  on the printed board  200 . Also, the negative pressure is adjusted so that the ejection angle θ becomes the favorable ejection angle θ 0 , and the mist flux M is secondarily ejected to the through-holes  210 , so that it is possible to eject the mist flux M to only a region intended to apply the flux. Thereby, it is possible to suppress the surplus flux from being unintentionally attached to the lower surface component  230 , which is not the applying target. In addition, it is possible to reduce an amount of the surplus flux to be attached to the inner surfaces of the through-holes  210  by adjusting the flow rate F. 
     The second nozzle  2  of the first illustrative embodiment is configured to be detachably attached to the first nozzle  1 , which is the existing nozzle to be generally used for a flux spray apparatus. For this reason, when it is not necessary to weaken the flow rate and ejection pressure of the flux to be applied, for example, the flux spray apparatus  100  can be used as the flux spray apparatus  100   a  of the related art by detaching the second nozzle  2 . 
     The above series of operations may be performed at a state where the negative pressure acts in the nozzle device  10  all the time and the negative pressure may be enabled to act at an ejection timing of the mist flux M. The negative pressure may be switched by manually operating the negative pressure generation device  50  or program-controlling the same with the negative pressure control device  60 . Meanwhile, in the flux spray apparatus  100 , the insides of the nozzle device  10  and the negative pressure pipe  30  are preferably cleaned by periodically ejecting IPA (isopropyl alcohol) or the like, so as to prevent the flux from being fixed to the inside of the nozzle device  10  and the inner surface of the negative pressure pipe  30 . Also, the liquid flux L separated by the flux solution collection device  40  may be discarded or may be reused for applying the flux. When reusing the liquid flux L, the flux solution collection device  400  is connected in communication with the flux solution supply device  20  and the collected flux solution L is pneumatically transported to the flux solution supply device  20 , so that the collected flux solution L is again supplied to the nozzle device  10 . 
     Operations and Effects of First Illustrative Embodiment 
     As described above, the flux spray apparatus  100  of the first illustrative embodiment includes the first nozzle  1  configured to eject the mist flux M and the second nozzle  2  provided around the first nozzle, and the second nozzle  2  is configured to suck a part of the mist flux M primarily ejected from the first nozzle  1  and to secondarily eject the remnant to the applying target. As a result, the flux spray apparatus  100  of the first illustrative embodiment has a structure simpler than the related art and can reduce the ejection amount and ejection pressure (flow strength) of the mist flux M and favorably apply the flux to the portions such as the through-holes or the components, which are difficult to be applied by the spray apparatus of the related art. 
     Also, according to the flux spray apparatus  100 , since the negative pressure generation device  50  is configured to communicate with the second nozzle  2 , it is possible to generate the suction pressure for sucking the mist flux M in the nozzle device  10  by operating the negative pressure generation device  50 . Also, the negative pressure generation device  50  can adjust the suction pressure. For this reason, according to the flux spray apparatus  100 , it is possible to perform the precise control of the ejection amount, which is difficult only by the control of the flow rate of the liquid flux L to be supplied from the flux solution supply device  20  to the first nozzle  1 . Also, since it is possible to adjust the ejection pressure of the mist flux M, it is possible to secondarily eject the mist flux M to the applying target with the favorable reaching distance and ejection angle. 
     Also, the flux spray apparatus  100  is configured so that the diameter of the introduction port  212  is greater than the first ejection port  11  of the first nozzle  1  and the first ejection port  11  is located in the introduction port  212  of the second nozzle  2 . Also, the flux spray apparatus  100  has the discharge ports  214  formed in the communication path  213 , and is configured to discharge a part of the mist flux M from the discharge ports  214  through the communication path  213  by the suction pressure. For this reason, according to the flux spray apparatus  100 , the mist flux M primarily ejected from the first nozzle  1  is substantially all introduced into the communication path  213 , and a part of the mist flux M can be discharged from the discharge ports  214 . 
     Herein, the discharge ports  214  may be arranged at any positions at which the primarily ejected mist flux M can be sucked. For example, the discharge ports may be arranged on the way of the communication path  213  but are preferably arranged in the vicinity of the first ejection port  11 . In the first illustrative embodiment, the discharge ports  214  are formed in the vicinity of the first ejection port  11 . For this reason, it is possible to suck the mist flux M before the mist flux completely spreads in the communication path  213  immediately after the primary ejection. As a result, it is possible to suppress the flux from being attached to the inside of the communication path  213 , thereby suppressing clogging of the second nozzle  2  and improving a rate of utilization of the flux. 
     Also, the discharge ports  214  may have any shape capable of discharging the mist flux M from the communication path  213 . For example, the discharge ports may be formed into holes opening towards the communication path  213 . Meanwhile, in the first illustrative embodiment, the introduction port  212  of the second nozzle  2  and the tapered part  13  of the first nozzle contact each other, so that the notches  212   a  and the tapered part  13  form the discharge ports  214 . Therefore, it is possible to form the discharge ports  214  in the vicinity of the first ejection port  11 . 
     Also, according to the flux spray apparatus  100 , the discharge ports  214  are provided with being equidistantly spaced over the entire circumference of the communication path  213 . Also, the discharge ports  214  are formed with the space A by the second nozzle  2 , and the negative pressure is enabled to act in the space A, so that a part of the mist flux M is sucked from the discharge ports  214  to the outside of the space A. That is, since the flux spray apparatus  100  can uniformly suck the mist flux M from the plurality of discharge ports  214  equidistantly spaced over the entire circumference of the communication path  213 , it is possible to secondarily eject the mist flux M in a uniform spray pattern. 
     Meanwhile, in the first illustrative embodiment, the main body part  21  of the second nozzle  2  has the introduction portion  21  b. However, in the disclosure, the introduction portion  21   b  is not necessarily provided. That is, the main body part  21  may not have the introduction portion  21   b,  and the large-diameter portion  21   c  may be formed with the introduction port  212  and the notches  212   a.  When the main body part  21  does not have the introduction portion  21   b,  it is possible to reduce the ejection amount and ejection pressure (flow strength) of the mist flux M with a structure simpler than the related art. 
     Second Illustrative Embodiment 
     A shape of a second nozzle  2   b  of a flux spray apparatus  100   b  in accordance with a second illustrative embodiment is different from the shape of the second nozzle  2  of the flux spray apparatus  100  of the first illustrative embodiment. In the below, the flux spray apparatus  100   b  of the second illustrative embodiment is described with reference to  FIG. 5 . In the meantime, the same configurations as the flux spray apparatus  100  of the first illustrative embodiment are denoted with the same reference numerals and the detailed descriptions thereof are omitted. 
       FIG. 5  depicts a nozzle device  10   b  of the flux spray apparatus  100   b.  The nozzle device  10   b  has a second nozzle  2   b  having a cylindrical shape. The second nozzle  2   b  is substantially the same as a shape in which the main body part  21  and the collar part  23  are omitted from the second nozzle  2  of the first illustrative embodiment. That is, the second nozzle  2   b  is substantially the same as the shape of the housing part  22  of the second nozzle  2 . Therefore, the second nozzle  2   b  has a cylindrical shape of which an inner diameter and an outer diameter are the same in the axial direction. The second nozzle  2   b  is axially divided into a passage part  213   b  and a housing part  22   b.  A tip of the passage part  213   b  is formed with a second opening ejection port  211   b  configured to eject the mist flux M to the applying target. A tip of the housing part  22   b  is formed with an opening  221   b  into which the first nozzle  1  is to be inserted. Also, the suction port  222  and the screw holes  223  are formed to penetrate side surfaces of the housing part  22   b.  The inner diameter of the second nozzle  2   b  is greater than the outer diameter of the straight cylinder part  12  of the first nozzle  1  by the fitting tolerance. 
     In order to mount the second nozzle  2   b  to the first nozzle  1  for assembling the nozzle device  10   b,  the second nozzle is externally fitted to the first nozzle  1  from an opening end  221  and the screws B (not shown) are tightened through the screw holes  223 . In the nozzle device  10   b,  the second nozzle  2   b  does not contact the outer surface of the straight cylinder part  12  at the position at which the suction port  222  is provided. Also, the passage part  213   b  is located in the Z direction with respect to the ejection port  11  of the first nozzle  1 . 
     When ejecting the mist flux M to the applying target by using the flux spray apparatus  100   b  of the second illustrative embodiment, it is also possible to reduce the amount and flow strength of the mist flux M to be ejected. The flux spray apparatus  100   b  is configured so that the negative pressure generation device  50  communicates with the inside of the nozzle device  10  via the negative pressure pipe  30  and the flux solution collection device  40 . When the negative pressure generation device  50  is operated, the suction pressure acts in the nozzle device  10   b  so that the exterior air is introduced from the second ejection port  211   b  and is discharged from the suction port  222 , as shown with an arrow B in (b) of  FIG. 5 . At this state, when the mist flux M is primarily ejected into the passage part  213   b  from the first nozzle  1 , a part of the mist flux M is sucked and is discharged from the suction port  222  to the outside of the nozzle device  10   b.  The remnant of the mist flux M is rectified while passing through the passage part  213   b,  and is then secondarily ejected from the second ejection port  211   b  to the applying target. 
     At this time, the diameter of the second ejection port  211   b  and the inner diameter of the passage part  213   b  are greater than the diameter of the second ejection port  211  and the diameter of the communication path  213  of the second nozzle  2  of the first illustrative embodiment. Also, since the nozzle device  10   b  does not have the discharge ports  214 , the mist flux M is sucked from the entire inside of the passage part  213   b.  For this reason, in the flux spray apparatus  100   b,  the more mist flux M is sucked, as compared to the flux spray apparatus  100  of the first illustrative embodiment. Thereby, the amount and flow strength of the mist flux M to be secondarily ejected are further reduced. As a result, the mist flux M to be secondarily ejected from the second ejection port  211   b  becomes a very small amount of feeble mist, like rising steam, and is then uniformly applied to the applying target. Also, since the mist flux M is secondarily ejected from the second ejection port  211   b  of which the diameter is greater than the second ejection port  211 , the mist flux M is secondarily ejected over a wider range, as compared to the flux spray apparatus  100  of the first illustrative embodiment. 
     Operations and Effects of Second Illustrative Embodiment 
     As described above, the flux spray apparatus  100   b  of the second illustrative embodiment has the second nozzle  2   b  having a simpler configuration than the second nozzle  2  of the first illustrative embodiment, so that it is possible to further reduce the amount and flow strength of the mist flux M to be secondarily ejected. As a result, it is possible to suppress the surplus mist flux M from passing through the through-holes  210  and from being attached to the inner surfaces of the through-holes  210 . That is, according to the flux spray apparatus  100   b  of the second illustrative embodiment, it is possible to reduce the ejection amount and ejection pressure (flow strength) of the mist flux M with the simpler structure and to favorably apply the flux to the portions such as the through-holes or the components, which are difficult to be applied by the spray apparatus of the related art. Also, it is possible to precisely control the amount and flow strength of the mist flux M to be ejected by adjusting the suction pressure that is to be generated by the negative pressure generation device  50 . Also, according to the flux spray apparatus  100   b  of the second illustrative embodiment, it is possible to uniformly apply the flux over the wider range, as compared to the flux spray apparatus  100  of the first illustrative embodiment. For this reason, the flux spray apparatus  100   b  of the second illustrative embodiment can be favorably used when applying the flux to the applying target in a short time over a wide range without limiting an applying region. 
     Embodiments 
     In the below, a comparison test of an embodiment of the flux spray apparatus of the first illustrative embodiment and a conventional example is described. However, the disclosure is not limited to the below embodiment. 
     A flux spray apparatus of the embodiment corresponds to the flux spray apparatus  100  of the first illustrative embodiment. That is, a nozzle device of the embodiment has a second nozzle corresponding to the second nozzle  2  mounted to a first nozzle corresponding to the first nozzle  1  and is configured to suck a part of a flux ejected from the first nozzle by applying a negative pressure. 
     A flux spray apparatus of the conventional example corresponds to the flux spray apparatus  100   a  of the related art. That is, the flux spray apparatus is an apparatus where the second nozzle is detached from the flux spray apparatus of the embodiment. 
     In the comparison test, the flux reaching distances in the embodiment and the conventional example are compared. In the test, the flux reaching distances are compared when ejecting the flux with the flux spray apparatus of the conventional example and when ejecting the flux with the flux spray apparatus of the embodiment. In the conventional example, the flux reaching distance is obtained by measuring a distance from the ejection port of the first nozzle to a position that the flux reaches, and in the embodiment, the flux reaching distance is obtained by measuring a distance from the ejection port of the second nozzle to a position that the flux reaches. In the embodiment and the conventional example, the first nozzles are the same and the flow rates and ejection pressures of the flux to be ejected from the first nozzles are the same. Also, in the embodiment, the negative pressure that is enabled to act in the nozzle device is changed stepwise and the flux reaching distance is measured at each negative pressure. 
       FIG. 6  is a graph depicting a result of the comparison test of the flux spray apparatuses of the embodiment and the conventional example. In the graph, a horizontal axis indicates an absolute value of the negative pressure to act in the flux spray apparatus and a vertical axis indicates the flux reaching distance. A result obtained when the negative pressure is 0 kPa is a result of the conventional example. As shown in  FIG. 6 , in the embodiment, as the absolute value of the negative pressure increases, the flux reaching distance becomes shorter. Also, in the embodiment, the flux reaching distance is not greater than the conventional example. 
     As described above, the flux spray apparatus of the embodiment has the second nozzle mounted to the first nozzle and sucks a part of the flux ejected from the first nozzle by using the negative pressure, thereby reducing the flux reaching distance, as compared to the conventional example. Also, it is possible to adjust the flux reaching distance by changing the magnitude of the negative pressure. 
     Modified Embodiments 
     In the above illustrative embodiments, the nozzle device  10 ;  10   b  is a device in which the first nozzle  1  and the second nozzle  2 ;  2   b,  which are separate members, are coupled with each other. However, the nozzle device  10 ;  10   b  of the disclosure may be a device in which the first nozzle  1  and the second nozzle  2 ;  2   b  are integrally formed. When the first nozzle  1  and the second nozzle  2 ;  2   b  of the nozzle device  10 ;  10   b  are integrally formed, it is possible to reduce the ejection amount and ejection pressure (flow strength) of the mist flux M with a simpler structure than the related art, without increasing the number of components. 
     In the above illustrative embodiments, the liquid that is to be ejected with the nozzle device  10 ;  10   b  is formed into the flux and the spray apparatus is the flux spray apparatus  100 ;  100   b.  However, the disclosure is not limited thereto. The liquid that is to be sprayed with the nozzle device  10 ;  10   b  is not particularly limited. For example, a coating material such as paint can also be favorably used. 
     In the meantime, the above descriptions can be combined as much as possible without departing from the technical spirit of the disclosure.