JP2011251296A - Method and device for feeding flux - Google Patents

Abstract

A flux supply amount can be controlled with a minute amount and with high accuracy, and a flux cleaning process is omitted.
A flux supply method according to the present invention includes a step of discharging molten solder droplets from a molten solder discharge device, and the molten solder droplets before the discharged molten solder droplets arrive at an object to be joined. Attaching flux to the surface of the substrate.
[Selection] Figure 1

Description

  The present invention relates to a flux supply method and a flux supply apparatus.

  Soldering is frequently used for joining electrodes of electronic components (for example, joining of lands and lead wires, mutual joining of a plurality of lands), bump formation on a substrate, and the like. In recent years, as electronic components have been miniaturized, a molten solder discharging apparatus that discharges molten solder in droplets has been proposed as a method for supplying a necessary amount of molten solder to a solder joint. For example, Patent Document 1 discloses a technique in which molten solder droplets discharged from a molten solder discharge device are joined to a base metal of a substrate and bumps are formed on the base metal.

  Generally, a flux is used when solder joining is performed using molten solder. The flux has (1) the function of cleaning the surface of the object to be joined, (2) the function of reducing the surface tension of the molten solder (improvement of wettability), and (3) the function of preventing reoxidation of the solder joint. . In order to supply such a flux, in Patent Document 1, a flux is applied in advance on a base metal that is an object to be joined, and molten solder droplets discharged from a molten solder discharge device collide with the base metal. . Patent Document 2 discloses that flux is applied to the tip of a nozzle that discharges molten solder droplets, and the flux is supplied to the molten solder droplets that pass through the nozzle opening.

JP 2009-188264 A JP-A-10-117059

  However, as described in Patent Document 1, in the method of causing the molten solder droplets discharged from the molten solder discharge device to collide with the joining object to which the flux is applied in advance, the flux supply amount is excessive. Molten solder movement (sliding, splashing, etc.) and bridges occur. For this reason, in order to implement | achieve sufficient joining force between molten solder and a to-be-joined object, it is necessary to control | control strictly the flux supply amount. As such a supply method, mask printing, spray coating, spin coating, dispense coating, and the like have been proposed. However, in any method, it is difficult to control the flux supply amount in a minute amount with high accuracy. Moreover, in the method described in Patent Document 1, a reflow process and a cleaning process are required after the molten solder is discharged in order to remove the flux applied to the objects to be joined.

  Further, in the method of supplying the flux through the nozzle opening as described in Patent Document 2, dirt (oxide or the like) around the nozzle may adhere to the molten solder droplets together with the flux. Therefore, there has been a demand for a method that can supply a clean flux to molten solder droplets and that can easily and precisely control the flux supply amount.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a novel, capable of controlling the amount of flux supplied with a small amount and high accuracy and omitting the flux cleaning step. Another object of the present invention is to provide an improved flux supply method and flux supply apparatus.

  In order to solve the above problems, according to one aspect of the present invention, a step of discharging molten solder droplets from a molten solder discharge device, and before the discharged molten solder droplets arrive at an object to be joined, And a step of attaching a flux to the surface of the molten solder droplet.

  The method further includes the step of supplying the flux onto an inclined guide disposed below the molten solder discharge device, and in the step of attaching the flux, the molten solder dropped onto the inclined guide from the molten solder discharge device The droplet is caused to slide on the inclined guide to which the flux is supplied, so that the flux is attached to the surface of the molten solder droplet, and the molten solder droplet to which the flux is attached is attached to the joining object. You may make it guide to.

  In the step of supplying the flux to a flux holder disposed below the molten solder discharge device and further forming a flux film in an opening provided in the flux holder, and attaching the flux, The molten solder droplet dropped toward the opening from the molten solder discharge device passes the flux film formed in the opening, thereby attaching the flux to the surface of the molten solder droplet, The molten solder droplets to which the flux is attached may be dropped on the objects to be joined.

  The method further includes the step of supplying the flux onto a reflecting table inclined below the molten solder discharge device, and in the step of attaching the flux, the molten dripped from the molten solder discharging device onto the reflecting table. The solder droplets are reflected by the reflecting table to which the flux is supplied, so that the flux adheres to the surface of the molten solder droplets, and the molten solder droplets to which the flux has adhered are attached to the joining object. You may make it guide to.

  In order to solve the above-mentioned problem, according to another aspect of the present invention, the molten solder droplets disposed between the molten solder discharge device and the object to be joined are discharged from the molten solder discharge device. Provided is a flux supply device comprising: a flux attachment portion that attaches a flux to the surface of the molten solder droplet before reaching the object to be joined; and a flux supply portion that supplies the flux to the flux attachment portion. The

  The flux adhering portion includes an inclined guide disposed below the molten solder discharge device, supplies the flux onto the inclined guide by the flux supply portion, and drops from the molten solder discharge device onto the inclined guide. The molten solder droplets are caused to slide on the inclined guide to which the flux is supplied, thereby causing the flux to adhere to the surface of the molten solder droplets and the molten solder droplets to which the flux has adhered. May be guided to the object to be joined.

  A guide groove is formed in the inclined guide along the sliding path of the molten solder droplet, and the flux is supplied while the flux is supplied to the guide groove of the inclined guide by the flux supply device. The molten solder droplet may be slid down in the guide groove.

  The flux adhering portion includes a flux holder disposed below the molten solder discharge device, and an opening for allowing the molten solder droplet dropped from the molten solder discharge device to pass through the flux holder. The molten solder that is supplied to the flux holder by the flux supply unit, forms a flux film in the opening, and is dropped from the molten solder discharge device toward the opening. The droplets pass through the flux film formed in the opening, thereby causing the flux to adhere to the surface of the molten solder droplets, and dropping the molten solder droplets to which the flux has adhered to the joining objects. You may make it do.

  The flux holder is a rotary table, and the opening is an annular slit formed in the rotary table, and the flux is supplied onto the rotary table by the flux supply unit while rotating the rotary table. Then, a flux film is formed in the slit, and the molten solder droplet dropped from the molten solder discharge device toward the slit passes through the flux film formed in the slit, thereby The flux may be attached to the surface of the solder droplet.

  The flux adhering portion includes a reflector that is inclined below the molten solder discharge device, supplies the flux onto the reflector by the flux supply unit, and from the molten solder discharge device onto the reflector. The molten solder droplets dropped are reflected by the reflecting table to which the flux is supplied, thereby causing the flux to adhere to the surface of the molten solder droplets and the molten solder droplets to which the flux has adhered. May be guided to the object to be joined.

  The flux adhering portion may further include an angle adjusting mechanism that adjusts an inclination angle of the reflecting table.

  According to the above configuration, the molten solder droplets are discharged from the molten solder discharge device, and the flux is attached to the surface of the molten solder droplets before the discharged molten solder droplets reach the object to be joined. Thereby, the supply amount of the flux to the solder joint portion of the joining object and the molten solder droplet can be controlled with a minute amount and with high accuracy.

  As described above, according to the present invention, the flux supply amount can be controlled with a small amount and with high accuracy, and the flux cleaning step can be omitted.

1 is a longitudinal sectional view showing an overall configuration of a sliding-down type flux supply device according to a first embodiment of the present invention. It is sectional drawing which shows the structure of the inclination guide of the sliding type flux supply apparatus which concerns on the embodiment. It is a flowchart which shows the molten solder discharge joining method using the flux supply method which concerns on the embodiment. It is a longitudinal cross-sectional view which shows the whole structure of the passage type flux supply apparatus which concerns on the same embodiment. It is a top view which shows the flux holding body of the passage type flux supply apparatus which concerns on the same embodiment. It is a side view which shows the flux holding body of the passage type flux supply apparatus which concerns on the same embodiment. It is a flowchart which shows the molten solder discharge joining method using the flux supply method which concerns on the embodiment. It is a longitudinal cross-sectional view which shows the whole structure of the reflection type flux supply apparatus which concerns on this embodiment. It is a top view which shows the reflective stand of the reflection type flux supply apparatus which concerns on this embodiment. It is a flowchart which shows the molten solder discharge joining method using the flux supply method which concerns on the embodiment. It is a flowchart which shows the soldering method which concerns on the 3rd Embodiment of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

The description will be made in the following order.
1. Outline of Embodiment of the Present Invention First Embodiment (Sliding Type Flux Supply Method)
3. Second Embodiment (Passing Type Flux Supply Method)
4). Third embodiment (reflection type flux supply method)
5). Summary

[1. Outline of Embodiment of the Present Invention]
First, an outline of a flux supply method according to a preferred embodiment of the present invention will be described. When soldering using molten solder (molten solder droplets) discharged from a molten solder discharge device in a droplet, in order to omit the cleaning process, the amount of flux supplied must be controlled with a very small amount and high accuracy. Therefore, it is required to supply a trace amount and a necessary and sufficient amount of flux. As a conventional flux supply method, a method of applying a flux to a bonding target in advance before discharging molten solder droplets from a molten solder discharging apparatus has been common. However, in this method, it is difficult to adjust the fine flux supply amount, and the flux is inevitably excessively supplied. For this reason, in the solder joint process, the molten solder moves and bridges in the solder joint, and a flux residue is generated around the solder joint even after the solder joint process, which requires a reflow process and a cleaning process. It was.

  The reason why the molten solder moves and bridges are considered as follows. When the molten solder droplet contacts the flux, the flux is heated rapidly, and the solvent contained in the flux is volatilized rapidly. As a result, it is presumed that the molten solder droplet is repelled from the joining object by being pushed out by the gas in which the flux is volatilized before forming the alloy layer with the joining object (land etc.). This phenomenon is considered to depend on the material of the solder and the object to be joined. For example, when the bonding object is an Au land, the Au land is relatively easy to diffuse into the solder, and the molten solder droplets that collide with the Au land form an alloy layer before being repelled. Drop movement hardly occurs. In addition, when the bonding object is a Cu land, the Cu land is less likely to diffuse into the solder than the Au land, and thus the molten solder droplets are likely to move.

  As described above, when a method of applying a flux in advance on an object to be joined is used as a flux supply method, the flux is inevitably excessively supplied. For this reason, there existed a problem that the movement of the molten solder droplet which collided with the joining object occurred, or a post-process such as a reflow process or a cleaning process was required.

  Therefore, in the flux supply method according to the embodiment of the present invention, the flux is not supplied to the joining object in advance, but reaches the joining object after the molten solder droplets are discharged from the molten solder discharge device. In the meantime, a flux is supplied to the molten solder droplets. For this purpose, a flux supply unit is installed between the molten solder discharge device and the object to be joined, and before the molten solder droplets discharged from the molten solder discharge device reach the object to be joined, the flux supply unit is Used to attach a minute amount of flux to the surface of the molten solder droplet.

  With such a flux supply method, the molten solder droplets are simply discharged from the molten solder discharge device to the bonding target, and the molten solder droplets are directly soldered to the bonding target without performing a pre-process such as flux application. It becomes possible to join. In addition, since the amount of flux supplied to the molten solder droplets can be controlled in a minute amount and with high accuracy, a necessary and sufficient amount of flux can be supplied to the solder joint. Furthermore, after soldering the molten solder droplet and the object to be joined, there is almost no flux residue around the object to be joined, so no subsequent steps such as a reflow process or a cleaning process to remove the flux residue are required. It becomes.

  The solder used in the following embodiments is preferably lead-free solder, but may be lead-containing solder (for example, Sn—Pb series). As the lead-free solder, for example, a solder having an alloy composition such as Sn—Ag—Cu, Sn—Zn, Sn—Bi, Sn—Bi—Ag (Au), Sn—Cu—Ni can be used. .

  In addition, the flux used in the following embodiments is activated when it contacts a molten solder droplet and reaches a specific temperature or more, and the three functions described above, namely, (1) a cleaning function of the surface of the joining object, (2 ) Demonstrate the function of lowering the surface tension of molten solder (improvement of wettability), and (3) the function of preventing reoxidation of solder joints. Examples of the flux include resin flux (main agent: rosin, rosin modified, synthetic resin, etc.), organic acid flux (main agent: water-based or solvent-based organic acid, etc.), inorganic acid flux (main agent: water-soluble) Or a water-insoluble inorganic acid etc.) can be used.

  In the following, the sliding-type, passing-type and reflective-type flux supply methods according to the first to third embodiments of the present invention will be described, but the type of flux is selected according to the characteristics of these three flux supply methods. It is preferable to do.

  For example, in the sliding-type flux supply method according to the first embodiment, it is preferable to use a liquid flux that has a low viscosity and is easy to flow in order to make it easier to slide molten solder droplets on the inclined guide. In the pass-type flux supply method according to the second embodiment, it is preferable to use a liquid flux so that a flux thin film can be easily formed. In the reflective flux supply method according to the third embodiment, it is preferable to use a flux having a high solid content concentration and a high viscosity in order to make the molten solder droplets more easily reflected on the reflecting table. . The flux may be any type of corrosive or non-corrosive flux. Moreover, you may change suitably activators other than the main ingredient contained in a flux, an additive, a solvent component, etc.

  Moreover, in the reflection type and sliding type flux supply methods according to the first and third embodiments, molten solder is discharged to members that are inclined. In the sliding-type flux supply method according to the first embodiment, in order to make it easy for molten solder droplets to slide on the inclined guide, the distance between the nozzle of the molten solder discharge device and the inclined guide is, for example, about 15 mm. Is preferred. If the distance is long, the temperature of the molten solder droplets is lower than that at the time of discharge (for example, about 100 ° C.) and the surface thereof becomes hard, so that the molten solder droplets easily slide down on the inclined guide. On the other hand, in the reflective flux supply method according to the third embodiment, the distance between the nozzle of the molten solder discharge device and the reflecting table is set within 5 mm, for example, in order to make the molten solder droplets easily reflect on the reflecting table. It is preferable to do. If the distance is short, the molten solder droplets maintain a temperature close to the high temperature at the time of discharge (for example, about 200 ° C.), and the surface is soft so that the molten solder droplets are easily reflected on the reflecting table. In addition, the specific numerical value of the said distance is a case where the diameter of the discharged molten solder droplet is 0.3 mm, and what is necessary is just to adjust the said distance according to the diameter of this molten solder droplet.

  In addition, the molten solder discharge apparatus used with the Lux supply method demonstrated below is comprised by the molten metal discharge apparatus which can discharge a molten metal to droplet shape, for example.

[2. First Embodiment]
Next, a sliding-type flux supply method and apparatus according to the first embodiment of the present invention will be described.

[2.1. Flux supply device]
Next, with reference to FIG.1 and FIG.2, the structure of the sliding type flux supply apparatus 20 which concerns on this embodiment is demonstrated. FIG. 1 is a longitudinal sectional view showing the overall configuration of the sliding-type flux supply device 20 according to this embodiment, and FIG. 2 shows the structure of the inclined guide 21 of the sliding-type flux supply device 20 according to this embodiment. It is sectional drawing shown.

  As shown in FIGS. 1 and 2, the sliding-type flux supply device 20 includes an inclined guide 21, a flux discharge device 22, and a waste flux receiving tank 23. The flux supply device 20 slides the molten solder droplet 1 dropped on the inclined guide 21 from the molten solder discharge device 10 on the inclined guide 21 while supplying the flux 2 onto the inclined guide 21 by the flux discharging device 22. As a result, the flux 2 is attached to the surface of the molten solder droplet 1 and the molten solder droplet to which the flux 2 is attached is guided to the joining object 3.

  The joining object 3 is an object to which the molten solder droplet 1 is joined, and is, for example, various boards such as a printed wiring board or an electronic component. By adhering the molten solder droplet 1 to lands, patterns, base metals, etc. formed on such a substrate, for example, bumps can be formed on the lands, or a plurality of lands can be joined to each other.

  The inclined guide 21 is an example of a flux attachment portion that attaches the flux 2 to the surface of the molten solder droplet 1. The inclined guide 21 is disposed below the molten solder discharge device 10, and is formed on the surface of the molten solder droplet 1 before the molten solder droplet 1 discharged from the molten solder discharge device 10 arrives at the bonding target 3. The flux 2 is adhered. The inclined guide 21 receives the molten solder droplet 1 dropped from the molten solder discharge device 10, slides the molten solder droplet 1 toward the bonding target object 3, and guides it onto the bonding target object 3. Have

  The inclined guide 21 is formed of, for example, a metal (for example, SUS) belt-like block, and is disposed immediately below the molten solder discharge device 10. The inclined guide 21 is disposed so as to be inclined such that the end portion on the joining target 3 side is lower than the end portion on the molten solder discharging apparatus 10 side. The mounting angle of the inclined guide 21 and the end of the joining target 3 side so that the molten solder droplet 1 slides down on the inclined guide 21 and jumps out from the lower end thereof and reaches the target position on the joining target 3. The position of is adjusted. Although the attachment angle of the inclined guide 21 can be adjusted arbitrarily, it is preferable to set it as 45-60 degrees, for example, considering that the molten solder droplet 1 slides down smoothly.

  As shown in FIG. 2, a V-shaped guide groove 24 is formed on the upper surface of the inclined guide 21 along the sliding path of the molten solder droplet 1. The flux 2 flows down in the V-shaped guide groove 24 and the molten solder droplet 1 slides down. The inclined guide 21 is disposed at a position where the guide groove 24 and the position where the molten solder droplet 1 is discharged are aligned. Since the molten solder droplet 1 can be slid straight down toward the joining object 3 by the guide groove 24, the positional accuracy when the molten solder droplet 1 is supplied to the joining object 3 can be improved. Further, since the flux 2 can be supplied only to a necessary portion on the inclined guide 21 by the guide groove 24, the supply amount of the flux 2 can be suppressed.

  The guide groove 24 may have any shape other than the V shape, such as a U shape, a semicircular shape, and a U shape, as long as the molten solder droplet 1 can slide. Further, in the inclined guide 21 of the example shown in FIG. 1, a linear guide groove 24 is formed along the longitudinal direction of the inclined guide 21, and the sliding path of the molten solder droplet 1 on the inclined guide 21 is a straight line. Is. However, the present invention is not limited to this example, and the sliding path of the molten solder droplet 1 may be, for example, a downwardly convex curved shape along the longitudinal direction of the inclined guide 21. As a result, the flight distance of the molten solder droplet 1 that protrudes from the lower end of the inclined guide 21 can be extended.

  Further, the structure of the inclined guide 21 is not limited to the guide rail shape shown in FIG. 1, and the design can be appropriately changed as long as the structure has an inclined sliding path through which the molten solder droplet 1 can slide. . Further, in order to improve the sliding property of the molten solder droplet 1 in the inclined guide 21, the sliding surface (the guide groove 24) of the inclined guide 21 may be subjected to processing such as diamond-like carbon processing (DLC processing). Good. Moreover, in order to improve the joining property of the joining target object 3 and the molten solder droplet 1, the joining target object 3 and the inclined guide 21 may be preheated at about 200 ° C., for example.

  The flux discharge device 22 is an example of a flux supply unit, and supplies the flux 2 to the inclined guide 21 that is a flux adhering unit. The flux discharge device 22 is configured by, for example, a liquid metering discharge device such as a dispenser, and is disposed immediately above the upper end portion side of the inclined guide 21 and supplies the flux 2 to the guide groove 24 of the inclined guide 21. The flux 2 adheres to the surface of the molten solder droplet 1 while the molten solder droplet 1 slides down on the guide groove 24 supplied with the flux 2 by the flux discharge device 22.

  In order to stably supply the flux 2 to the molten solder droplet 1, the flux discharge device 22 always supplies the flux 2 to the inclined guide 21 during the discharge of the molten solder droplet 1. Moreover, the flux discharge port 25 is provided in the position of about 3 mm from the lower end of the inclination guide 21, for example so that the flux 2 which flowed down on the inclination guide 21 may not be dripped at the joining target objects 3, such as a printed wiring board. The flux discharge port 25 is formed by a hole that is formed through the bottom of the guide groove 24 in the vertical direction. The diameter of the flux discharge port 25 is adjusted according to the diameter of the molten solder droplet 1 to be discharged, and is large enough to prevent the molten solder droplet 1 (for example, 0.3 mm in diameter) from dropping (for example, 0.1 mm in diameter). Set to The flux 2 flowing down in the guide groove 24 of the inclined guide 21 is collected from the flux discharge port 25 into a waste flux receiving tank 23 provided below the flux 2.

[2.2. Flux supply method]
Next, a flux supply method using the sliding-type flux supply device 20 and a molten solder discharge joining method using the method will be described with reference to FIG. FIG. 3 is a flowchart showing a molten solder discharge joining method using the flux supply method according to the present embodiment.

  As shown in FIG. 3, first, the flux 2 is started to be supplied to the guide groove 24 of the inclined guide 21 by the flux supply device 20 (step S100). The flux 2 supplied from the flux supply device 20 to the upper end side of the inclined guide 21 flows down in the guide groove 24 of the inclined guide 21 and is discharged from the flux discharge port 25 to the waste flux receiving tank 23. The supply of the flux 2 is continuously performed until the solder joint in S112 is completed.

  Next, when the heat capacity of the joining object 3 is equal to or higher than the reference value (step S102), the joining object 3 and the inclined guide 21 are preheated to, for example, about 200 ° C. by a heating device (not shown) (step S104). . By such preliminary heating, the bonding property between the bonding object 3 and the molten solder droplet 1 in the solder bonding step S112 is improved. On the other hand, when the heat capacity of the joining object 3 is less than the reference value (step S102), the process proceeds to S106 without preheating. The reference value is set according to the temperature or material of the molten solder droplet 1. When the activation time (oxide film removal time) of the flux 2 is longer than the time required for producing the electronic component, shortening of the activation time can be realized by performing preheating.

  Thereafter, the molten solder droplet 1 is discharged from the molten solder discharge device 10, and the molten solder droplet 1 is dropped into the guide groove 24 of the inclined guide 21 supplied with the flux 2 in S100 (step S106). Then, the molten solder droplet 1 takes on the flux 2 while sliding down on the guide groove 24 of the inclined guide 21 supplied with the flux 2 (step S108). As a result, as shown in FIGS. 1 and 2, the flux 2 adheres to the entire surface of the molten solder droplet 1 in the form of a film.

  Further, the molten solder droplet 1 to which the flux 2 is attached jumps out from the lower end of the inclined guide 21, flies along a curved locus, and collides with the target position of the joining object 3 (step S <b> 110). In this way, the inclined guide 21 guides the molten solder droplet 1 sliding down so that the molten solder droplet 1 collides with the target position of the object 3 to be joined. As a result, the molten solder droplet 1 and the bonding object 3 are bonded to each other while the oxide film of the bonding object 3 and the molten solder droplet 1 is removed by the flux 2 attached to the molten solder droplet 1. Solder joining is completed (step S112).

  As described above, according to the flux supply method according to the present embodiment, the molten solder droplets 1 discharged from the molten solder discharge device 10 are supplied with the flux 2 before reaching the joining object 3. Slide down on the inclined guide 21. As a result, a fine amount of flux 2 necessary and sufficient for soldering can be adhered to the surface of the molten solder droplet 1, and the supply amount of the flux 2 can be strictly controlled. Therefore, the molten solder droplet 1 to which the flux 2 adheres can be suitably joined to the joining object 3 and there is almost no residue of the flux 2 after joining. Therefore, it is not necessary to clean the solder joint after the solder joining process, and the reflow process and the cleaning process can be omitted.

[3. Second Embodiment]
Next, a passing type flux supply method and apparatus according to a second embodiment of the present invention will be described.

[3.1. Flux supply device]
First, with reference to FIGS. 4 to 6, the configuration of a pass-type flux supply device 30 according to the second embodiment will be described. FIG. 4 is a longitudinal sectional view showing the overall configuration of the pass-type flux supply device 30 according to the present embodiment. FIG. 5 and FIG. 6 are a top view and a side view, respectively, showing the flux holder 31 of the pass-type flux supply device 30 according to this embodiment.

  As shown in FIGS. 4 to 6, the pass-type flux supply device 30 includes a disk-shaped flux holder 31, a flux supply roller 32, and a slit 33 formed in the flux holder 31. The flux supply device 30 supplies the flux 2 onto the flux holder 31 by the flux supply roller 32 to form a flux thin film 34 in the slit 33. Thereby, when the molten solder droplet 1 dropped from the molten solder discharge device 10 toward the object to be joined 3 passes through the flux thin film 34 formed in the slit 33, the surface of the molten solder droplet 1. The flux 2 adheres to the surface, and the molten solder droplet 1 to which the flux 2 adheres is dropped onto the joining object 3.

  The flux holder 31 is an example of a flux attachment part that attaches the flux 2 to the surface of the molten solder droplet 1. As shown in the figure, the flux holder 31 is constituted by, for example, a horizontally arranged disk-shaped rotary table, and has a function of holding the flux 2 supplied by the flux supply roller 32. The disk-shaped flux holder 31 is disposed between the molten solder discharge device 10 and the bonding target object 3, and before the molten solder droplet 1 dropped from the molten solder discharge device 10 arrives at the bonding target object 3. Next, the flux 2 is attached to the surface of the molten solder droplet 1.

  The flux holder 31 is formed with an annular slit 33 penetrating in the vertical direction as an opening for allowing the molten solder droplet 1 dropped from the molten solder discharge device 10 to pass therethrough. The annular slit 33 is formed concentrically with the disk-shaped flux holder 31 and is disposed immediately below the molten solder discharge device 10. The width of the slit 33 is adjusted to such a width that the molten solder droplet 1 can pass through and the flux thin film 34 can be formed in the slit 33. For example, when the diameter of the molten solder droplet 1 is 0.3 mm, the width of the slit 33 may be about 1 mm.

  The flux supply roller 32 is an example of a flux supply unit, and has a function of supplying the flux 2 onto the flux holder 31 that is a flux adhering unit. As shown in the figure, the flux supply roller 32 is constituted by, for example, a truncated cone-shaped roller made of a material (for example, sponge) that can be impregnated with the flux 2, and the outer periphery of the flux supply roller 32 is a flux holder 31. It is in contact with the top surface. When the disk-shaped flux holder 31 rotates around the rotation shaft 35, the flux supply roller 32 also rotates around the rotation shaft 36 following the rotation of the flux holder 31.

  While supplying the flux 2 from the dispenser or the like (not shown) to the flux supply roller 32, the disk-shaped flux holder 31 is rotated at a constant speed. Thereby, the flux 2 is uniformly and continuously applied to the upper surface of the flux holder 31, and a thin film of the flux 2 is formed on the flux holder 31. In order to stably supply the flux 2 to the molten solder droplet 1, the flux holder 31 is always rotated during the discharge of the molten solder droplet 1, and the flux is supplied onto the flux holder 31 by the flux supply roller 32. Continue to supply 2.

  When the flux 2 is supplied onto the flux holder 31 by the flux supply roller 32, the flux 2 enters the slit 33 as shown in FIG. 4, and the flux thin film enters the slit 33 due to the surface tension of the flux 2. 34 is formed. In this state, when the molten solder droplet 1 is discharged from the molten solder discharge device 10 toward the joining object 3, the molten solder droplet 1 passes through the flux thin film 34 formed in the slit 33. At this time, due to the surface tension of the flux thin film 34, the flux 2 adheres to the entire surface of the molten solder droplet 1, and the molten solder droplet 1 to which the flux 2 adheres falls onto the joining object 3. Thus, in this embodiment, the flux 2 is supplied to the surface of the molten solder droplet 1 by passing the flux thin film 34.

  Note that by changing the thickness of the flux holder 31 (that is, the depth of the slit 33), the thickness of the flux thin film 34 in the slit 33 also changes. Thereby, the adhesion amount of the flux 2 with respect to the molten solder droplet 1 can be adjusted. Moreover, in order to improve the joining property of the joining target object 3 and the molten solder droplet 1, the joining target object 3 may be preheated at about 200 ° C., for example.

  Further, in the above example, the annular slit 33 is provided in the flux holder 31 as an opening for allowing the molten solder droplet 1 to pass through, but the present invention is not limited to this example. As long as the molten solder droplet 1 can pass therethrough and can form a flux film, it may be, for example, a linear slit, one or two or more through holes. Further, the flux holder 31 may be of any shape as long as it is a member capable of holding the flux 2, even if it is not a disk-shaped rotary table.

[3.2. Flux supply method]
Next, with reference to FIG. 7, a flux supply method using the above-described pass-type flux supply device 30 and a molten solder discharge joining method using the method will be described. FIG. 7 is a flowchart showing a molten solder discharge joining method using the flux supply method according to the present embodiment.

  As shown in FIG. 7, first, the flux 2 is supplied onto the flux holder 31 by the flux supply roller 32 (step S200). Specifically, the disk-shaped flux holder 31 is rotated while supplying the flux 2 to the flux supply roller 32. As a result, the flux 2 is applied onto the flux holder 31, and a flux film having an appropriate thickness is formed. Next, by further rotating the flux holder 31, the flux 2 penetrates into the slit 33 of the flux holder 31, and a flux thin film 34 (see FIG. 4) is formed in the slit 33 (step S202). The supply of the flux 2 and the formation of the flux thin film 34 are continuously performed until the solder bonding in S214 is completed.

  Next, when the heat capacity of the joining object 3 is equal to or higher than the reference value (step S204), the joining object 3 is preheated to, for example, about 200 ° C. by a heating device (not shown) (step S206). By such preheating, the bonding property between the bonding object 3 and the molten solder droplet 1 in the solder bonding step S212 is improved. On the other hand, when the heat capacity of the bonding target 3 is less than the reference value (step S204), the process proceeds to S208 without preheating.

  Thereafter, the molten solder droplet 1 is discharged from the molten solder discharge device 10, and the molten solder droplet 1 is dropped into the slit 33 of the flux holder 31 on which the flux thin film 34 is formed in S202 (step S208). . Then, the molten solder droplet 1 takes on the flux 2 when passing through the flux thin film 34 in the slit 33 (step S210). As a result, as shown in FIG. 4, the flux 2 adheres to the entire surface of the molten solder droplet 1 in the form of a film.

  Further, the molten solder droplet 1 to which the flux 2 is adhered falls from the position of the slit 33 toward the joining target 3 and collides with the target position of the joining target 3 (step S212). As a result, the molten solder droplet 1 and the bonding object 3 are bonded to each other while the oxide film of the bonding object 3 and the molten solder droplet 1 is removed by the flux 2 attached to the molten solder droplet 1. The soldering is completed (step S214).

  As described above, according to the flux supply method according to this embodiment, the molten solder droplet 1 discharged from the molten solder discharge apparatus 10 forms the flux thin film 34 until it reaches the bonding target 3. It passes through the made opening (slit 33). As a result, a fine amount of flux 2 necessary and sufficient for soldering can be adhered to the surface of the molten solder droplet 1, and the supply amount of the flux 2 can be strictly controlled. Therefore, the molten solder droplet 1 to which the flux 2 adheres can be suitably joined to the joining object 3 and there is almost no residue of the flux 2 after joining. Therefore, it is not necessary to clean the solder joint after the solder joining process, and the reflow process and the cleaning process can be omitted.

[4. Third Embodiment]
Next, a reflective flux supply method and apparatus according to a third embodiment of the present invention will be described.

[4.1. Flux supply device]
First, with reference to FIGS. 8-10, the structure of the reflective flux supply apparatus 40 which concerns on 3rd Embodiment is demonstrated. FIG. 8 is a longitudinal sectional view showing the overall configuration of the reflective flux supply device 40 according to the present embodiment. FIGS. 9 and 10 are a top view and a side view, respectively, showing a reflecting table 41 of the reflective flux supply device 40 according to the present embodiment.

  As shown in FIGS. 8 to 10, the reflective flux supply device 40 includes a disk-shaped reflection table 41, a flux supply roller 42, and a slit 33 formed in the reflection table 41. The flux supply device 40 supplies the molten solder droplets 1 dropped from the molten solder discharge device 10 on the reflection table 41 supplied with the flux 2 while supplying the flux 2 onto the reflection table 41 by the flux supply roller 42. Reflect. As a result, the flux 2 is attached to the surface of the molten solder droplet 1, and the molten solder droplet 1 to which the flux 2 is attached is guided to the joining object 3.

  The reflection table 41 is an example of a flux attachment part that attaches the flux 2 to the surface of the molten solder droplet 1. As shown in the figure, the reflecting table 41 is constituted by, for example, a horizontally arranged disk-shaped rotary table, and has a function of holding the flux 2 supplied by the flux supply roller 42. The reflection table 41 is inclined and disposed below the molten solder discharge apparatus 10. The upper surface of the reflection table 41 is a reflection surface 43 for reflecting the molten solder droplet 1 dropped from the molten solder discharge device 10, and the reflection surface 43 causes the molten solder droplet 1 to be bonded to the bonding target 3. In order to reflect the light, it is inclined at an appropriate angle with respect to the horizontal plane. The reflector 41 reflects the molten solder droplet 1 on the reflective surface 43 to which the flux 2 is supplied, so that the molten solder droplet 1 dropped from the molten solder discharge device 10 arrives at the joining object 3. Next, the flux 2 is attached to the surface of the molten solder droplet 1.

  The flux supply roller 42 is an example of a flux supply unit, and has a function of supplying the flux 2 onto the reflection table 41 that is a flux adhesion portion. As shown in the figure, the flux supply roller 42 is constituted by a truncated cone-shaped roller made of a material (for example, sponge) that can be impregnated with the flux 2, and the outer periphery of the flux supply roller 42 is Touching the top surface. When the disk-shaped reflecting table 41 rotates around the rotation shaft 44, the flux supply roller 42 also rotates around the rotation shaft 45 following the rotation of the reflecting table 41.

  While supplying the flux 2 from the dispenser or the like (not shown) to the flux supply roller 42, the disk-shaped reflecting table 41 is rotated at a constant speed. As a result, the flux 2 is uniformly and continuously applied to the upper surface of the reflecting table 41, and a thin film of the flux 2 is formed on the reflecting table 41. In order to stably supply the flux 2 to the molten solder droplet 1, the reflecting table 41 is always rotated during the discharge of the molten solder droplet 1, and the flux 2 is supplied onto the reflecting table 41 by the flux supply roller 42. Continue to supply.

  When the thin film of the flux 2 is formed on the reflecting table 41 as described above, when the reflecting table 41 is dropped from the molten solder discharge device 10, the molten solder droplet 1 is reflected on the reflecting table 41. The direction of travel changes. When the molten solder droplet 1 is reflected in this way, the flux 2 on the reflection table 41 adheres to the entire surface of the molten solder droplet 1. Then, the molten solder droplet 1 to which the flux 2 adheres flies toward the joining object 3 and falls onto the joining object 3. As described above, in this embodiment, the flux 2 is supplied to the surface of the molten solder droplet 1 by reflecting the molten solder droplet 1 on the reflector 41 on which the thin film of the flux 2 is formed.

  In order to always reflect the molten solder droplet 1 on the reflecting table 41 under the same conditions (flux film thickness), it is preferable that the disk-shaped reflecting table 41 always rotates at a constant speed. Further, by controlling the rotation speed of the reflecting table 41 or the flux supply roller 42, the amount of the flux 2 attached to the molten solder droplet 1 can be adjusted. As the rotational speed of the flux supply roller 42 is increased, the supply amount of the flux 2 from the flux supply roller 42 to the reflecting table 41 is decreased, so that the supply amount of the flux 2 to the molten solder droplet 1 is also decreased. On the other hand, the slower the rotational speed of the flux supply roller 42, the greater the amount of flux 2 supplied from the flux supply roller 42 to the reflector 41, and the greater the amount of flux 2 supplied to the molten solder droplet 1.

  In addition, an angle adjustment mechanism for adjusting the inclination angle θ of the reflection surface 43 of the reflection table 41 (see FIG. (Not shown) may be provided. Thereby, since the molten solder droplet 1 reflected by the reflecting table 41 can be guided to a desired position of the joining object 3, it becomes possible to flexibly cope with a change in the type of the joining object 3 and the target position. . Moreover, in order to improve the joining property of the joining object 3 and the molten solder droplet 1, the joining object 3 and the reflection table 41 may be preheated at about 200 ° C., for example.

  The structure of the reflecting table 41 is not limited to the example of the disk-shaped rotary table shown in FIG. 8, and the design can be changed as long as it has a reflecting surface 43 that can reflect the molten solder droplet 1. Is possible. Further, the method of supplying the flux 2 to the reflecting table 41 is not limited to the example of the rotation mechanism and the flux supply roller 42 described above. For example, a certain amount of flux 2 may be supplied from the flux discharge device such as a dispenser to the upper side of the reflection table 41 so that the flux 2 flows down on the reflection surface 43.

[4.2. Flux supply method]
Next, a flux supply method using the reflective flux supply device 40 and a molten solder discharge joining method using the method will be described with reference to FIG. FIG. 11 is a flowchart showing a molten solder discharge joining method using the flux supply method according to the present embodiment.

  As shown in FIG. 11, first, the flux 2 is supplied onto the reflector 41 by the flux supply roller 42 (step S300). Specifically, the disk-shaped reflecting table 41 is rotated while supplying the flux 2 to the flux supply roller 42. As a result, the flux 2 is applied onto the reflecting table 41, and a flux film having an appropriate thickness is formed. The supply of the flux 2 is continuously performed until the solder joint of S314 is completed.

  Next, the reflection direction of the molten solder droplet 1 on the reflection table 41 is adjusted by adjusting the inclination angle of the reflection surface 43 of the reflection table 41 to an appropriate angle by the angle adjustment mechanism (step S302). By adjusting the angle, the molten solder droplet 1 reflected on the reflecting table 41 can be guided to the target position of the joining object 3.

  Next, when the heat capacity of the joining object 3 is equal to or higher than the reference value (step S304), the joining object 3 is preheated to, for example, about 200 ° C. by a heating device (not shown) (step S306). By such preliminary heating, the bonding property between the bonding object 3 and the molten solder droplet 1 in the solder bonding step S312 is improved. On the other hand, when the heat capacity of the bonding object 3 is less than the reference value (step S304), the process proceeds to S308 without preheating.

  Thereafter, the molten solder droplet 1 is discharged from the molten solder discharge device 10, and the molten solder droplet 1 is dropped onto the reflector 41 on which the thin film of the flux 2 is formed in S302 (step S308). Then, when the molten solder droplet 1 is reflected by the reflecting surface 43 of the reflecting table 41, it comes into contact with the thin film of the flux 2 formed on the reflecting table 41 and takes on the flux 2 (step S310). As a result, as shown in FIG. 8, the flux 2 adheres to the entire surface of the molten solder droplet 1 in the form of a film.

  Furthermore, the molten solder droplet 1 to which the flux 2 is attached flies along a curved trajectory from the reflecting table 41 toward the joining object 3 and collides with the target position of the joining object 3 (step S312). As a result, the molten solder droplet 1 and the bonding object 3 are bonded to each other while the oxide film of the bonding object 3 and the molten solder droplet 1 is removed by the flux 2 attached to the molten solder droplet 1. Then, the solder joint is completed (step S314).

As described above, according to the flux supply method according to the present embodiment, the molten solder droplet 1 discharged from the molten solder discharge device 10 is on the reflection surface 43 before reaching the bonding target 3. The light is reflected by a reflecting table 41 on which a thin film of flux 2 is formed. As a result, a fine amount of flux 2 necessary and sufficient for soldering can be adhered to the surface of the molten solder droplet 1, and the supply amount of the flux 2 can be strictly controlled. Therefore, the molten solder droplet 1 to which the flux 2 adheres can be suitably joined to the joining object 3 and there is almost no residue of the flux 2 after joining. Therefore, it is not necessary to clean the solder joint after the solder joining process, and the reflow process and the cleaning process can be omitted.
[5. Summary]

  The flux adjusting methods and apparatuses according to the first to third embodiments have been described above. In conventional flux supply methods (printing method, dispensing method, etc.), the amount of flux supplied cannot be controlled in a minute amount with high accuracy, and thus the flux is excessively supplied. For this reason, the process which wash | cleans the flap remaining in the periphery of a solder joint part was required after solder joint.

  On the other hand, according to the present embodiment, the molten solder droplet 1 is discharged from the molten solder discharge device 10 until the molten solder droplet 1 arrives at the object 3 to be joined. A flux 2 is supplied to the droplet 1. That is, the flux 2 is attached to the surface of the molten solder droplet 1 while the molten solder droplet 1 discharged from the molten solder discharge device 10 arrives at the object 3 to be joined. Thereby, since the supply amount of the flux 2 to the solder joint portion can be controlled with a minute amount and with high accuracy, the solder joint can be performed with the minimum necessary flux supply. As a result, the flux cleaning process can be omitted, and the manufacturing cost can be suppressed.

  Further, in the conventional molten solder discharge joining method, it is necessary to supply the flux to the joining objects in advance before discharging the molten solder droplets. Further, in the printing method which is a conventional flux supply method, it is difficult to supply the flux to the region of the bonding target object having unevenness in the periphery. Also, with the dispensing method, it was difficult to supply a trace amount with high accuracy. However, according to the present embodiment, it is not necessary to supply the flux 2 to the joining object 3, and the molten solder discharge contact is also applied to the region of the joining object 3 that was impossible by the printing method or the dispensing method. Lawfulness will be applicable.

  Furthermore, since the supply amount of the flux 2 can be strictly controlled, stable solder bonding and bump formation can be realized inexpensively and simply. Further, not only the flux cleaning process but also the reflow process can be omitted, and the flux supply method can be simplified.

  In addition, in other conventional flux supply methods, the flux is supplied at the nozzle opening of the molten solder discharge device. In this method, dirt (oxide or the like) around the nozzle together with the flux adheres to the molten solder droplets. On the other hand, in this embodiment, since the flux 2 is supplied at a position away from the nozzle of the molten solder discharge device, dirt around the nozzle does not adhere to the molten solder droplets.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Molten solder droplet 2 Flux 3 Joining object 10 Molten solder discharge apparatus 20 Sliding-type flux supply apparatus 21 Inclined guide 22 Flux discharge apparatus 23 Waste flux receiving tank 24 Guide groove 25 Flux discharge port 30 Pass-type flux supply apparatus 31 Flux holder 32 Flux supply roller 33 Slit 34 Flux thin film 35, 36 Rotating shaft 40 Reflective flux supplying device 41 Reflecting table 42 Flux supplying roller 43 Reflecting surface 44, 45 Rotating shaft

Claims (11)

A step of discharging molten solder droplets from a molten solder discharge device;
Attaching the flux to the surface of the molten solder droplets before the discharged molten solder droplets arrive at the object to be joined;
A flux supply method. Further comprising supplying the flux on an inclined guide disposed below the molten solder discharge device;
In the step of attaching the flux, the molten solder droplet dropped on the inclined guide from the molten solder discharge device is slid down on the inclined guide to which the flux is supplied, thereby the molten solder droplet. The flux supply method according to claim 1, wherein the flux is attached to the surface of the solder and the molten solder droplets to which the flux is attached are guided to the object to be joined. Further comprising supplying the flux to a flux holder disposed below the molten solder discharge device to form a flux film in an opening provided in the flux holder,
In the step of attaching the flux, the molten solder droplets dropped from the molten solder discharge device toward the opening pass through the flux film formed in the opening, thereby forming the molten solder droplets. The flux supply method according to claim 1, wherein the flux is attached to a surface, and the molten solder droplets to which the flux is attached are dropped onto the objects to be joined. Further comprising the step of supplying the flux on a reflector that is inclined and disposed below the molten solder discharge device;
In the step of attaching the flux, the molten solder droplets dropped on the reflecting table from the molten solder discharge device are reflected by the reflecting table to which the flux is supplied, thereby forming the molten solder droplets. The flux supply method according to claim 1, wherein the flux is attached to a surface, and the molten solder droplet to which the flux is attached is guided to the joining target. It is arranged between the molten solder discharge device and the object to be joined, and the flux adheres to the surface of the molten solder droplet before the molten solder droplet discharged from the molten solder discharge device arrives at the object to be joined. A flux adhering portion to be
A flux supply part for supplying the flux to the flux adhering part;
A flux supply device. The flux adhering portion includes an inclined guide disposed below the molten solder discharge device,
The flux is supplied onto the inclined guide by the flux supply unit, and the molten solder droplets dropped onto the inclined guide from the molten solder discharge device are slid down on the inclined guide supplied with the flux. The flux supply apparatus according to claim 5, wherein the flux is attached to the surface of the molten solder droplet, and the molten solder droplet to which the flux is attached is guided to the object to be joined. In the inclined guide, a guide groove is formed along a sliding path of the molten solder droplet,
The flux supply device according to claim 6, wherein the molten solder droplet is slid down in the guide groove to which the flux is supplied while the flux is supplied to the guide groove of the inclined guide by the flux supply device. The flux adhering portion includes a flux holder disposed below the molten solder discharge device,
The flux holder is provided with an opening for allowing the molten solder droplets dropped from the molten solder discharge device to pass through,
The flux is supplied onto the flux holder by the flux supply unit, a flux film is formed in the opening, and the molten solder droplet dropped from the molten solder discharge device toward the opening is the opening. The flux is attached to the surface of the molten solder droplets by passing through the flux film formed on the surface of the molten solder droplets, and the molten solder droplets to which the flux is adhered are dropped onto the joining object. The flux supply apparatus described. The flux holder is a rotary table;
The opening is an annular slit formed in the rotary table,
While the rotary table is rotated, the flux is supplied onto the rotary table by the flux supply unit, a flux film is formed on the slit, and the melt is dropped from the molten solder discharge device toward the slit. The flux supply apparatus according to claim 8, wherein the solder droplets pass through the flux film formed in the slit, thereby causing the flux to adhere to the surface of the molten solder droplets. The flux adhering portion includes a reflecting table that is inclined below the molten solder discharge device,
The flux is supplied onto the reflecting table by the flux supply unit, and the molten solder droplets dropped on the reflecting table from the molten solder discharge device are reflected by the reflecting table supplied with the flux. The flux supply apparatus according to claim 5, wherein the flux is attached to the surface of the molten solder droplets, and the molten solder droplets to which the flux is attached are guided to the object to be joined. The flux supply apparatus according to claim 10, wherein the flux adhering portion further includes an angle adjustment mechanism that adjusts an inclination angle of the reflecting table.

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