WO2022168664A1

WO2022168664A1 - Flow soldering device

Info

Publication number: WO2022168664A1
Application number: PCT/JP2022/002582
Authority: WO
Inventors: 典也南; 隆俵原
Original assignee: 三菱電機株式会社
Priority date: 2021-02-08
Filing date: 2022-01-25
Publication date: 2022-08-11
Also published as: JPWO2022168664A1; CN116802005A

Abstract

A flow soldering device (1) is provided with a flux application unit (1), a preheating unit (5), a flow soldering body unit (7), and a transport mechanism (9). In the flow soldering body unit (7), jet nozzles (19), dross suppression devices (31), a solder bath heater (21), impellers (23), and jet motors (25) are arranged in a solder bath (15) storing a molten solder (17). The dross suppression devices (31) are arranged in a floating manner on the molten solder (17) in a region where the molten solder (17) jetted from the jet nozzles (19) falls onto the molten solder (17) stored in the solder bath (15).

Description

Flow soldering equipment

The present disclosure relates to flow soldering equipment.

Flow soldering is one method of soldering electronic components to printed wiring boards. In flow soldering, an electronic component is soldered to a printed wiring board by jetting molten solder and contacting or immersing the printed wiring board on which the electronic component is mounted in the jet.

In flow soldering, dross, which is an oxide of solder, is generated by jetting molten solder. If dross is mixed in the molten solder, there is a risk of defective soldering. In addition, the state of jetting molten solder may become unstable. Therefore, a flow soldering apparatus that performs flow soldering is required to suppress the generation of dross. For example, Patent Literature 1 proposes a method of suppressing the generation of dross by using a substantially spherical ceramic body.

Japanese Patent Application Laid-Open No. 2007-237269

When dross occurs in a flow soldering device, in addition to defective soldering, work to collect the dross is required, so the flow soldering work will stop during the collection work. For this reason, flow soldering devices are required to further suppress the generation of dross.

The present disclosure has been made as part of such development, and its purpose is to provide a flow soldering apparatus capable of suppressing the generation of dross.

A flow soldering apparatus according to the present disclosure is a flow soldering apparatus that solders an object to be soldered by contacting the object to be soldered with a jet of molten solder. and a restraining jig. The transport unit transports the object to be soldered in the first direction. Molten solder is stored in the solder bath. The jet nozzle is arranged in the solder bath and jets the molten solder stored in the solder bath toward the object to be soldered transported by the transport unit. The dross suppression jig is arranged in the solder bath. The jet nozzle has a width in a second direction that intersects the first direction. The length of the dross suppression jig in the second direction is longer than the width. The dross suppression jig is in contact with the molten solder in a region where the molten solder jetted from the jet nozzle drops into the molten solder stored in the solder bath, and protrudes from the liquid surface of the molten solder. are arranged along the

According to the flow soldering apparatus according to the present disclosure, the dross suppressing jig contacts the molten solder in the area where the molten solder jetted from the jet nozzle drops into the molten solder stored in the solder bath, and is arranged in such a manner as to protrude from the liquid surface of the As a result, it is possible to suppress entrainment of air in the molten solder by dropping the jetted molten solder onto the dross suppression jig. As a result, the generation of dross can be suppressed.

1 is a side view including a partial cross section, showing the configuration of a flow soldering apparatus according to Embodiment 1; FIG. FIG. 4 is a top view schematically showing the configuration of the flow soldering main body in the same embodiment. FIG. 7 is a partial cross-sectional view according to a comparative example for explaining the action and effect of the dross suppressing jig in the flow soldering apparatus in the same embodiment; FIG. 4 is a first partial cross-sectional view for explaining the effects of the dross suppressing jig in the flow soldering apparatus in the same embodiment; FIG. 10 is a second partial cross-sectional view for explaining the effects of the dross suppression jig in the flow soldering apparatus in the same embodiment; FIG. 11 is a third partial cross-sectional view for explaining the effects of the dross suppression jig in the flow soldering apparatus in the same embodiment; FIG. 11 is a fourth partial cross-sectional view for explaining the effects of the dross suppression jig in the flow soldering apparatus in the same embodiment; FIG. 10 is a first cross-sectional view for explaining variations in the shape of the dross suppression jig in the same embodiment; FIG. 10 is a second cross-sectional view for explaining variations in the shape of the dross suppression jig in the same embodiment; FIG. 11 is a third cross-sectional view for explaining variations in the shape of the dross suppression jig in the same embodiment; FIG. 11 is a fourth cross-sectional view for explaining variations in the shape of the dross suppression jig in the same embodiment; FIG. 11 is a fifth cross-sectional view for explaining variations in the shape of the dross suppression jig in the same embodiment; FIG. 11 is a sixth cross-sectional view for explaining variations in the shape of the dross suppression jig in the same embodiment; FIG. 10 is a first top view for explaining variations of a member for fixing the dross suppression jig in the same embodiment; FIG. 10 is a second top view for explaining variations of the member for fixing the dross suppression jig in the same embodiment. FIG. 10 is a third top view for explaining variations of the member for fixing the dross suppression jig in the same embodiment; FIG. 10 is a partial perspective view for explaining variations of a member for fixing the dross suppression jig in the same embodiment; FIG. 11 is a side view including a partial cross section, showing the structure of a flow soldering main body in a flow soldering apparatus according to Embodiment 2; FIG. 4 is a first partial cross-sectional view for explaining the effects of the dross suppressing jig in the flow soldering apparatus in the same embodiment; FIG. 10 is a second partial cross-sectional view for explaining the effects of the dross suppression jig in the flow soldering apparatus in the same embodiment; FIG. 11 is a third partial cross-sectional view for explaining the effects of the dross suppression jig in the flow soldering apparatus in the same embodiment; FIG. 10 is a first cross-sectional view schematically showing the configuration of a flow soldering main body including a dross suppressing jig in a flow soldering apparatus according to Embodiment 3; FIG. 4 is a second cross-sectional view schematically showing the configuration of the flow soldering main body including the dross suppressing jig in the flow soldering apparatus of the same embodiment. FIG. 11 is a cross-sectional view schematically showing the configuration of a flow soldering main body including a dross suppressing jig in a flow soldering apparatus according to Embodiment 4; FIG. 11 is a top view showing a dross suppressing jig and a nozzle in a flow soldering apparatus according to Embodiment 5; In the embodiment, it is a cross-sectional view of a dross suppression jig.

Embodiment 1.
An example of the flow soldering apparatus according to Embodiment 1 will be described. For convenience of explanation, the X-axis, Y-axis and Z-axis will be used. The X-axis direction corresponds to the first direction, the Y-axis direction corresponds to the second direction, and the Z-axis direction corresponds to the third direction.

As shown in FIG. 1, the flow soldering apparatus 1 includes a flux applying section 3, a preheating section 5, a flow soldering body section 7, and a transport mechanism 9. A printed wiring board 51 to be soldered is conveyed in the X-axis direction (see arrow Y1) by a conveying mechanism 9 as a conveying unit to the flux applying unit 3, the preheating unit 5, and the flow soldering body unit 7 in this order. .

In the flux applying section 3, the flux 11 is applied toward the soldering surface 51a of the printed wiring board 51 on which the electronic component 53 is mounted. Methods for applying the flux 11 include, for example, a spray method, a foaming method, and an immersion method.

A preheater 13 is provided in the preheating section 5 . In preheating section 5 , printed wiring board 51 coated with flux 11 is preheated by preheater 13 . The purpose of preheating is to heat the printed wiring board 51 to volatilize the solvent of the flux 11, to exhibit the effect of removing the oxide film of the flux 11, and to improve the solderability. Heating methods include, for example, infrared rays, far infrared rays, hot air, and the like. Only the lower surface (soldering surface 51a) of the printed wiring board 51 may be heated. Moreover, the upper surface of the printed wiring board 51 on which the electronic components 53 are mounted may also be heated.

As shown in FIGS. 1 and 2, the flow soldering main body 7 includes a solder bath 15. As shown in FIG. Molten solder 17 is stored in the solder bath 15 . As molten solder 17, Sn--Pb eutectic solder, Sn--Ag--Cu solder, or Sn--Cu solder, for example, is used. Sn--Pb eutectic solder is a solder containing lead. Sn--Ag--Cu based solder and Sn--Cu based solder are lead-free solders that do not contain lead.

A jet nozzle 19 , a dross suppression jig 31 , a solder bath heater 21 , an impeller 23 and a jet motor 25 are arranged in the solder bath 15 . The jet nozzle 19 jets the molten solder 17 toward the printed wiring board 51 . The jet motor 25 rotates the impeller 23 to send the molten solder 17 to the jet nozzle 19 , thereby jetting the molten solder 17 from the jet nozzle 19 .

The jet nozzle 19 has a width WN in the Y-axis direction that intersects with the X-axis direction (see arrow Y1). The jet nozzle 19 includes a primary nozzle 19a and a secondary nozzle 19b. The primary nozzle 19a is arranged on the upstream side in the transport direction (see arrow Y1). The secondary nozzle 19b is arranged downstream in the transport direction (see arrow Y1).

The molten solder 17 is jetted from the primary nozzle 19a so that relatively rough waves are formed on the surface of the molten solder 17 . The molten solder 17 jetted from the primary nozzle 19 a contacts every corner of the soldering surface 51 a of the printed wiring board 51 .

On the other hand, the molten solder 17 is jetted from the secondary nozzle 19b so as to form relatively gentle waves on the surface of the molten solder 17. The molten solder 17 jetted from the secondary nozzle 19 b adheres to the soldering surface 51 a of the printed wiring board 51 in an amount suitable for soldering the electronic component 53 .

The dross suppression jig 31 is arranged in a manner that it floats on the molten solder 17 in a region (position) where the molten solder 17 jetted from the jet nozzle 19 falls onto the molten solder 17 stored in the solder bath 15. The dross suppression jig 31 has a function of suppressing the generation of dross by reducing the height at which the molten solder 17 jetted from the jet nozzle 19 falls onto the molten solder 17 stored in the solder bath 15 . This will be discussed later.

The dross suppression jig 31 is a columnar (bar-shaped) solid structure extending in the Y-axis direction. The cross section (ZX plane) of the dross suppression jig 31 is circular. The dross suppression jig 31 has a length LD longer than the width WN of the jet nozzle 19 in the Y-axis direction. That is, the dross suppression jig 31 has a length LD longer than the width of the molten solder 17 jetted from the jet nozzle 19 . The dross suppressing jig 31 includes a dross suppressing jig 32 , a dross suppressing jig 33 and a dross suppressing jig 34 . The dross suppression jig 32 , the dross suppression jig 33 , and the dross suppression jig 34 are connected by a fixing member 37 .

The dross suppression jig 31 is restricted in movement in the X-axis direction (see arrow Y1) and in the Y-axis direction. The dross suppression jig 31 is allowed to move in the Z-axis direction (vertical direction) while floating on the molten solder 17 . As a result, the dross suppression jig 31 remains in the area (position) where the jetted molten solder 17 falls.

The dross suppression jig 32 is arranged upstream in the transport direction (see arrow Y1) with respect to the primary nozzle 19a. The dross suppression jig 33 is arranged downstream in the transport direction (see arrow Y1) with respect to the primary nozzle 19a. Also, the dross suppression jig 33 is arranged on the upstream side in the transport direction (see arrow Y1) with respect to the secondary nozzle 19b. The dross suppression jig 34 is arranged downstream in the transport direction (see arrow Y1) with respect to the secondary nozzle 19b.

The dross suppression jig 31 is made of a material (raw material) that has heat resistance (for example, about 250 to 300° C.) and does not get wet with the molten solder 17 . As a material of the dross suppression jig 31, for example, stainless steel (for example, SUS304 or SUS316), aluminum or titanium is applied.

The specific gravity of stainless steel is higher than that of general molten lead-free solder. Common lead-free solders include, for example, Sn-3Ag-0.5Cu solder and Sn-0.7Cu-Ni solder. Therefore, when a molten lead-free solder is used as the molten solder and stainless steel is used as the material of the dross suppression jig 31, the dross suppression jig 31 has, for example, a hollow structure in which both ends of a hollow pipe are closed. It is said that The specific gravity of aluminum and titanium is less than that of molten solder. Therefore, when aluminum or titanium is applied, the dross suppression jig 31 may have either a solid structure or a hollow structure.

The corrosion resistance of stainless steel to the molten solder 17 is higher than the corrosion resistance of aluminum to the molten solder 17. Therefore, stainless steel has less erosion than aluminum. Next, when aluminum is used as the material of the dross suppressing jig 31, aluminum is relatively light metal, so it is excellent in workability. In the case of aluminum, it is desirable to improve corrosion resistance by, for example, alumite treatment so that the oxide film on the surface is not broken.

In addition, since aluminum has high thermal conductivity, the dross suppression jig 31 is likely to cool down after the dross suppression jig 31 is removed from the solder bath 15 during cleaning work. As a result, the time required for the dross suppression jig 31 to cool down to a temperature suitable for cleaning work is shortened, and the time required for cleaning can be shortened. As a result, productivity of the flow soldering apparatus 1 can be improved. When titanium is used as the material of the dross suppressing jig 31, the dross suppressing jig 31 has excellent corrosion resistance.

Also, as the material of the dross suppressing jig 31, wood or heat insulating material having low thermal conductivity may be applied. Since these materials have relatively low thermal conductivity, it is possible to suppress the temperature drop of the molten solder 17 due to the heat radiation from the surface of the dross suppression jig 31 . The flow soldering apparatus 1 according to Embodiment 1 is configured as described above.

Next, an example of the operation of the flow soldering apparatus 1 described above will be described. The printed wiring board 51 loaded into the flow soldering apparatus 1 is set on the transport mechanism 9 . An electronic component 53 to be soldered is mounted on the printed wiring board 51 (see FIG. 1).

The printed wiring board 51 is first transported to the flux applying section 3 by the transport mechanism 9 . At the flux applying section 3 , the flux 11 is applied to the soldering surface 51 a of the printed wiring board 51 . Next, the printed wiring board 51 is transported to the preheating section 5 by the transport mechanism 9 . In preheating section 5 , printed wiring board 51 is heated by preheater 13 .

Next, the printed wiring board 51 is transported to the flow soldering body section 7 by the transport mechanism 9 . In the flow soldering body portion 7 , first, the molten solder 17 jetted from the primary nozzle 19 a of the jet nozzles 19 contacts the entire soldering surface 51 a of the printed wiring board 51 . Next, the molten solder 17 jetted from the secondary nozzle 19b adheres to the soldering surface 51a.

Here, when the impeller 23 is rotated to jet the molten solder 17 from the jet nozzle 19 in a state where the molten solder 17 is not jetted from the jet nozzle 19, the liquid level of the molten solder 17 is lowered. As the liquid level of the molten solder 17 lowers, the dross suppression jig 31 floating on the molten solder 17 also lowers.

The molten solder 17 jetted from the jet nozzle 19 falls onto the dross suppression jig 31 and flows along the surface of the dross suppression jig 31 into the molten solder 17 stored in the solder bath 15 (see FIG. 4). . The printed wiring board 51 with the molten solder 17 adhering to the soldering surface 51 a is gradually cooled while being transported by the transport mechanism 9 . The cooled printed wiring board 51 is carried out from the flow soldering apparatus 1 and transported to the next process. Thus, a series of steps for soldering the electronic component 53 to the printed wiring board 51 is completed.

In the flow soldering apparatus 1 described above, the jetted molten solder 17 once falls on the dross suppression jig 31, thereby suppressing the entrainment of air in the molten solder 17 and suppressing the generation of dross. . This will be explained.

As shown in FIG. 3, as a comparative example, in the flow soldering apparatus 1 in which the dross suppression jig is not arranged, the molten solder 17 jetted from the jet nozzle 19 (see arrow Y2) is melted and stored in the solder bath. It falls almost perpendicularly to the liquid surface of the solder 17 (see the downward arrow). In this case, the height HC from which the jetted molten solder 17 falls corresponds substantially to the height of the jet nozzle 19 .

In the region FR where the jetted molten solder 17 falls onto the molten solder 17 stored in the solder bath, a large pulsation occurs on the liquid surface of the molten solder 17, and surrounding air is caught in the molten solder 17. For this reason, the molten solder 17 is easily oxidized, and a sherbet-like dross in which the molten solder 17 and the dross are mixed is generated, and the amount of dross increases.

On the other hand, as shown in FIG. 4, in the flow soldering apparatus 1 in which the dross suppressing jig 31 is arranged, the molten solder 17 jetted from the jet nozzle 19 (see arrow Y2) drops onto the dross suppressing jig 31, It flows along the surface of the suppressing jig 31 into the molten solder 17 stored in the solder bath 15 .

Because the jetted molten solder 17 once falls on the dross suppression jig 31, the height HE at which the jetted molten solder 17 drops is lower than the height HC according to the comparative example. This reduces the amount of ambient air entrained in the molten solder 17 .

In addition, the molten solder 17 that has fallen onto the dross suppression jig 31 flows along the surface of the dross suppression jig 31 and obliquely with respect to the liquid surface of the stored molten solder 17 . For this reason, compared to the case where the jetted molten solder 17 falls on the liquid surface of the pooled molten solder 17 substantially perpendicularly, the speed at which the jetted molten solder 17 flows into the pooled molten solder 17 increases in the depth direction. component becomes smaller. As a result, the jetted molten solder 17 sinks into the pooled molten solder 17 to a shallower depth, further reducing the amount of ambient air that the molten solder 17 is entrained in.

Furthermore, the velocity component in the depth direction of the velocity at which the jetted molten solder 17 flows into the pooled molten solder 17 is reduced, so that the fluctuation of the liquid surface of the pooled molten solder 17 is also suppressed. As a result, the generation of dross can be greatly suppressed.

Further, as shown in FIG. 2, the length LD in the Y-axis direction of the dross suppressing jig 31 arranged in the flow soldering main body 7 is longer than the width WN of the jet nozzle 19 . As a result, the dross generated due to the molten solder 17 jetted from the jet nozzle 19 can be handled by one dross suppressing jig 31 arranged upstream with respect to the jet nozzle 19 and one dross suppressing jig 31 arranged downstream of the jet nozzle 19. The dross suppression jig 31 suppresses the dross. As a result, the number of dross suppression jigs 31 to be arranged can be minimized.

Further, by making the shape of the dross suppressing jig 31 cylindrical (bar-like), when a certain amount or more of dross accumulates on the surface of the dross suppressing jig 31, the dross will drop onto the molten solder 17. become. This can prevent the dross suppression jig 31 from sinking into the molten solder 17 as the dross accumulates on the surface of the dross suppression jig 31 .

In addition, when cleaning the liquid surface of the molten solder 17 stored in the solder bath 15, it is necessary to remove the dross suppressing jigs 31 from the solder bath 15. can be reduced to shorten the working time.

Furthermore, cleaning work is also required to remove residual flux or dross adhering to the dross suppressing jigs 31, but minimizing the number of dross suppressing jigs 31 shortens the work time. can.

Also, in the flow soldering apparatus 1 , the dross suppressing jig 31 is arranged so as to float on the molten solder 17 . As a result, even if the position (height) of the liquid surface of the molten solder 17 stored in the solder bath 15 fluctuates, the dross suppression jig 31 is not exposed away from the stored molten solder 17. It is possible to prevent the jetted molten solder 17 from dropping perpendicularly to the liquid surface of the stored molten solder 17 .

Furthermore, by arranging the dross suppression jig 31 so as to follow the liquid surface of the molten solder 17, bring it into contact with the liquid surface, and protrude from the liquid surface, even if the liquid surface of the molten solder 17 fluctuates. , entrainment of air in the molten solder 17 is suppressed. 5, 6 and 7 show changes in the liquid surface of the molten solder 17 stored in the solder bath. FIG. 5 shows the state before the molten solder 17 is jetted from the jet nozzle 19 . FIG. 6 shows one state after the molten solder 17 is jetted from the jet nozzle 19 . FIG. 7 shows a state after the molten solder 17 has jetted from the jet nozzle 19 for a relatively long time.

As shown in FIGS. 5 and 6, when the molten solder 17 is jetted from the jet nozzle 19, the liquid level of the molten solder 17 stored in the solder bath drops from position P1 to position P2. Further, as shown in FIGS. 6 and 7, by attaching the molten solder 17 to the soldering surfaces 51a of the printed wiring boards 51 that are conveyed in sequence, the molten solder 17 is consumed and stored in the solder bath. The liquid level of the molten solder 17 is gradually lowered, and the liquid level of the molten solder 17 is lowered from the position P2 to the position P3. Therefore, the height at which the jetted molten solder 17 falls gradually increases as the molten solder 17 is consumed.

On the other hand, since the dross suppression jig 31 is arranged so as to float on the molten solder 17, the dross suppression jig 31 is separated from the stored molten solder 17 and is not exposed. As a result, even if the falling height of the jetted molten solder 17 gradually increases, it is possible to prevent the jetted molten solder 17 from dropping perpendicularly to the liquid surface of the pooled molten solder 17. can. As a result, the amount of surrounding air entrained in the molten solder 17 is reduced, which contributes to the reduction of dross generation.

Also, the diameter of the cross section (ZX plane, see FIG. 7) of the dross suppression jig 31 should be set to a relatively large diameter in consideration of the height (position) where the liquid level of the molten solder 17 drops. Therefore, it is possible to reduce the influence of the lowering of the liquid level of the molten solder 17 .

Next, variations in the shape of the dross suppression jig 31 will be described. As shown in FIGS. 8 and 9, the dross suppressing jig 31 has a circular cross section (ZX plane, see FIG. 1). The dross suppression jig 31 shown in FIG. 8 is a solid structure. The dross suppression jig 31 shown in FIG. 9 is a hollow structure. Also, as shown in FIG. 10, there is an elliptical shape. The dross suppression jig 31 shown in FIG. 10 is a solid structure.

In addition, there are quadrilaterals (rectangles) shown in FIG. 11, or polygons containing triangles shown in FIG. Also, as shown in FIG. 13, a shape combining a rectangle and a circle may be used. The dross suppression jig 31 shown in FIGS. 11, 12 and 13 is a hollow structure. Note that the circular, square, and elliptical shapes are not intended to be mathematically (geometrically) strict, but include manufacturing errors and the like. It also includes shapes that appear to be circular, square or elliptical at first glance.

In the case of the dross suppression jig 31 having a circular cross-sectional shape, even if the dross suppression jig 31 rotates as the molten solder 17 jetted from the jet nozzle 19 drops, the cross-sectional shape of the dross suppression jig 31 does not change. Therefore, the effect of suppressing dross can be suppressed from fluctuating and made constant.

In the case of the hollow structure dross suppression jig 31 (see FIGS. 9, 11, 12, etc.), for example, if a hollow pipe or a pipe is applied, a commercially available standard A member can be applied, and the dross suppression jig 31 can be easily manufactured.

In the case of the dross suppression jig 31 having an elliptical cross-sectional shape, the dross suppression jig 31 floats on the molten solder 17 so that the long axis of the ellipse is along the liquid surface of the molten solder 17 . As a result, the molten solder 17 jetted from the jet nozzle 19 and dropped onto the dross suppression jig 31 flows more gently into the molten solder 17 stored in the solder bath 15 . Therefore, it is possible to reduce the flow rate of the dropped molten solder 17 into the pooled molten solder 17, thereby contributing to the reduction of dross.

In the case of the dross suppression jig 31 having a quadrangular (rectangular) cross-sectional shape, since the outer peripheral surface is configured by a flat surface, flux residues can be easily cleaned. In addition, a commercially available standard member can be applied in terms of shape, and the dross suppression jig 31 can be easily manufactured.

In the case of the dross suppression jig 31 having a triangular cross-sectional shape, the dross suppression jig 31 is floated on the molten solder 17 so that the vertex of the triangle faces upward. It branches into two streams. As a result, when the molten solder 17 flows into the pooled molten solder 17, entrainment of air is suppressed, which contributes to the reduction of dross.

In the case of the dross suppressing jig 31 having a combination of rectangular and circular cross-sectional shapes, the effect of the dross suppressing jig 31 having a rectangular cross-sectional shape and the effect of the dross suppressing jig 31 having a circular cross-sectional shape are obtained. Both effects are obtained.

The cross-sectional shape may be a dross suppressing jig having a polygonal cross-sectional shape of pentagon or more, and the effect is substantially the same as that of the dross suppressing jig 31 having a rectangular cross-sectional shape, or , substantially the same effect as in the case of the dross suppression jig 31 having a circular cross-sectional shape can be obtained.

Next, the connection mode of the dross suppression jig 31 will be described. As shown in FIG. 14, with respect to the jet nozzle 19 (19a), the dross suppression jig 31 (32) arranged upstream in the conveying direction, and the dross suppression jig 31 (33) arranged downstream. are connected to each other by a fixing member 37 . Therefore, the dross suppressing jig 31 (32, 33) is restricted from moving in the X-axis direction and the Y-axis direction while floating in the molten solder 17, and is allowed to move in the Z-axis direction (vertical direction). be.

As the fixing member 37, for example, a wire-shaped, plate-shaped or pipe-shaped metal member can be applied. A U-shaped rod-shaped metal member can also be used. Alternatively, as shown in FIGS. 15 and 16, the connection member 29 may be attached to the dross suppression jig 31, and the fixing member 37 may be attached to the connection member 29. FIG. As the connection member 29, for example, a member obtained by processing a metal pipe into a U shape can be applied.

Furthermore, as shown in FIG. 17, the dross suppression jig 31 may be attached to a pair of guide members 27 provided with guide grooves 27a. The guide groove 27a allows the dross suppression jig 31 to move vertically (see the arrow) according to the height of the liquid surface of the molten solder.

Embodiment 2.
Here, as a second embodiment, an example of a flow soldering apparatus in which a plurality of dross suppressing jigs are arranged in one region (position) where the jetted molten solder falls onto the stored molten solder will be described.

As shown in FIG. 18, in the flow soldering main body 7 of the flow soldering apparatus 1, a dross suppressing jig 32a and a dross suppressing jig 32a are provided upstream of the primary nozzle 19a in the conveying direction (see arrow Y1). A jig 32b is arranged.

A dross suppression jig 33a, a dross suppression jig 33b, and a dross suppression jig 33c are arranged downstream of the primary nozzle 19a in the transport direction (see arrow Y1). The dross suppression jigs 33a, 33b, and 33c are arranged on the upstream side in the transport direction (see arrow Y1) with respect to the secondary nozzle 19b.

A dross suppression jig 34a and a dross suppression jig 34b are arranged downstream of the secondary nozzle 19b in the transport direction (see arrow Y1). Since the configuration other than this is the same as that of the flow soldering apparatus 1 shown in FIG. 1, the same members are denoted by the same reference numerals, and the description thereof will not be repeated unless necessary.

Next, an example of the operation of the flow soldering apparatus 1 described above will be described. First, similarly to the flow soldering apparatus 1 described above, the printed wiring board 51 on which electronic components are mounted is conveyed to the flux applying section 3 by the conveying mechanism 9 and flux is applied. Next, the printed wiring board 51 is conveyed to the preheating section 5 and heated (see FIG. 1).

Next, the printed wiring board 51 is transported to the flow soldering body portion 7 by the transport mechanism 9 (see FIG. 18). In the flow soldering body portion 7 , the molten solder 17 jetted from the primary nozzle 19 a contacts the entire soldering surface 51 a of the printed wiring board 51 . Next, the molten solder 17 jetted from the secondary nozzle 19b adheres to the soldering surface 51a. After that, the cooled printed wiring board 51 is carried out from the flow soldering apparatus 1 to complete a series of soldering steps.

In the above-described flow soldering apparatus 1, a plurality of dross suppression jigs 31 are arranged in one region where the jetted molten solder 17 falls, so that the generation of dross can be effectively suppressed. This will be explained.

First, by arranging a plurality of dross suppression jigs 31 on the molten solder 17 stored in the solder bath 15, the area of the stored molten solder 17 exposed to air is reduced. Oxidation of the stored molten solder 17 can thereby be suppressed, and dross generation can be effectively suppressed.

Further, as shown in FIG. 19, the molten solder 17 jetted from the jet nozzle 19 and dropped onto the dross suppression jig 31a is branched into two flows of the molten solder 17. As shown in FIG. That is, a flow that flows along the surface of the dross suppression jig 31a and then flows into the pooled molten solder 17 (flow A: see arrow Y21), and a flow that flows from the surface of the dross suppression jig 31a to the surface of the dross suppression jig 31b. , and then branches into a flow that flows into the pooled molten solder 17 (flow B: see arrow Y22).

The molten solder 17 that has fallen onto the dross suppression jig 31a is split into flows A and B, so that the amount of the flow A is reduced by the amount of the flow B from the amount of the molten solder 17 that has fallen. Therefore, entrainment of air in the molten solder 17 accompanying the flow A can be reduced.

On the other hand, since the flow B flows from the surface of the dross suppression jig 31a along the surface of the dross suppression jig 31b, the flow velocity decreases step by step. Therefore, the flow velocity of the molten solder 17 flowing into the pooled molten solder 17 is suppressed, and the amount of air entrained in the molten solder 17 can be reduced. As a result, the oxidation of the molten solder 17 is suppressed, and the generation of dross can be effectively suppressed.

The dross suppression jig 31a, the dross suppression jig 31b, and the like are connected by a fixing member (not shown). Alternatively, the dross suppression jigs 31a and 31b may be fixed together.

As the dross suppressing jig 31, a plurality of dross suppressing jigs having different heights from the liquid surface of the molten solder 17 are provided while the dross suppressing jig 31 is in contact with the pooled molten solder 17. Tool 31 may be used.

In the dross suppression jig 31 shown in FIG. 20, the height HB of the dross suppression jig 31b from the liquid surface of the molten solder 17 is lower than the height HA of the dross suppression jig 31a from the liquid surface of the molten solder 17. , a dross suppression jig 31a and a dross suppression jig 31b are arranged. The dross suppressing jig 31 is arranged so that the height of the dross suppressing jig 31 from the liquid surface of the molten solder 17 decreases as the distance from the jet nozzle 19 increases.

Here, as an example, a dross suppression jig 31a and a dross suppression jig 31b having a circular cross-sectional shape are arranged. The diameter of the dross suppression jig 31a is relatively large, and the diameter of the dross suppression jig 31b is relatively small.

In such a dross suppression jig 31, the spouted molten solder 17 flows from the surface of the dross suppression jig 31a along the surface of the dross suppression jig 31b, and then drops when flowing into the stored molten solder 17. The height HE to move is lower. As a result, the flow velocity of the jetted molten solder 17 into the pooled molten solder 17 is suppressed, and the amount of the molten solder 17 that entrains the surrounding air is further reduced. As a result, the generation of dross can be further suppressed.

Furthermore, by arranging a plurality of dross suppression jigs 31 in one area where the jetted molten solder 17 falls, lump-like dross can be reduced.

As shown in FIG. 21, when the spouted molten solder 17 flows along the dross suppression jigs 31 (31a, 31b), it is disturbed in the region between the dross suppression jigs 31a and 31b. A flow (see arrow Y3) is likely to occur. When the molten solder 17 is turbulent, the surface of the molten solder 17 is likely to generate lump-like dross 61 containing components of the solder.

However, even if lump-like dross is generated by the turbulent flow of the molten solder 17, the turbulent flow of the molten solder 17 stirs the lump-like dross. As a result, the clumped dross 61 is pulverized, and the components of the solder involved are remelted and returned to molten solder, leaving powdery dross. As a result, wasteful consumption of solder can be suppressed.

Also, the dross 61 floats and accumulates on the jetted molten solder 17 flowing over the dross suppression jig 31 . This can prevent the dross 61 from entering the molten solder 17 and, for example, prevent the jet nozzle 19 from clogging due to the dross entering the inside of the jet nozzle 19 .

Embodiment 3.
Here, as a third embodiment, an example of a flow soldering apparatus equipped with a dross suppressing jig having an attracting member will be described.

As shown in FIG. 22, the adsorption member 41 is mounted so as to cover the surface of the dross suppression jig 31 made of aluminum or the like. The adsorption member 41 is detachable. The adsorption member 41 is fibrous, and for example, pulp waste, cotton, linen, or heat-resistant felt is applied.

The configuration of the flow soldering apparatus 1 other than the dross suppressing jig 31 is the same as that of the flow soldering apparatus 1 shown in FIG. do. Also, the operation of the flow soldering apparatus 1 is the same as the operation of the flow soldering apparatus 1 shown in FIG.

According to the flow soldering apparatus 1 described above, the dross and flux residue generated in the solder bath 15 are adsorbed by the adsorption member 41 provided on the surface of the dross suppression jig 31 . In the flow soldering apparatus 1 , flux applied to the soldering surface 51 a of the printed wiring board 51 in the flux applying section 3 (see FIG. 1 ) is melted by jetting molten solder 17 and flows into the solder bath 15 . . The adsorption member 41 adsorbs powdery dross and residual flux that has flowed into the solder bath 15 .

By the flux residue being adsorbed by the adsorption member 41 , it is possible to prevent the flux residue from adhering to the inside of the solder bath 15 . In addition, by adsorbing the powdery dross to the adsorption member 41, it is possible to suppress the powdery dross from spreading on the liquid surface of the pooled molten solder 17. FIG.

The adsorption member 41 that has adsorbed the flux residue and dross can be removed from the dross suppression jig 31 and discarded, thereby shortening the cleaning time and contributing to the improvement of productivity. Also, the flux residue has a reducing function from the end of soldering until it is completely carbonized. As a result, the effect of reducing the dross adsorbed to the adsorption member 41 is also obtained. As a result, the generation of dross can be further suppressed.

Incidentally, as shown in FIG. 23, the dross suppression jig 31 itself may be formed from the adsorption member 41 . Forming the dross suppression jig 31 from the adsorption member 41 eliminates the need to remove the adsorption member 41 . Further, by forming the dross suppressing jig 31 from the adsorption member 41, the amount of adsorbed flux residue and dross is increased, and the frequency of discarding the adsorption member 41 (dross suppression jig 31) can be reduced. .

Embodiment 4.
Here, as a fourth embodiment, an example of a flow soldering apparatus equipped with a dross suppression jig including a surface-treated portion having solder wettability will be described.

As shown in FIG. 24, the surface of the dross suppression jig 31 is formed with a surface-treated portion 43 having solder wettability. The surface-treated portion 43 is made of copper (Cu), nickel (Ni), or iron (Fe). Since copper (Cu) may gradually dissolve in the molten solder 17, the outermost surface is desirably covered with an iron (Fe) layer or a nickel (Ni) layer.

According to the flow soldering apparatus 1 described above, the surface of the dross suppressing jig 31 is formed with the surface-treated portion 43 having solder wettability. As a result, when the molten solder 17 jetted from the jet nozzle 19 falls onto the dross suppression jig 31, the molten solder 17 wets and spreads on the surface treatment portion 43, and then flows into the stored molten solder 17. Become.

In the dross suppressing jig 31, the dropped molten solder 17 spreads out, so that the flow of the molten solder 17 becomes gentler compared to the dross suppressing jig in which the surface-treated portion 43 is not formed. As a result, the pulsation that occurs on the liquid surface of the pooled molten solder 17 is suppressed, and the generation of dross can be suppressed more effectively.

In addition, in the flow soldering apparatus 1 according to each of the above-described embodiments, the case where the dross suppressing jig 31 is arranged in the solder bath 15 so as to float on the molten solder 17 has been described as an example. The arrangement of the dross suppressing jig is not limited to this. The dross suppression jig may be arranged in such a manner as to

Even with such a dross suppression jig, by once dropping the jetted molten solder onto the dross suppression jig, it is possible to suppress the entrainment of air in the molten solder and suppress the generation of dross. can.

Embodiment 5.
Here, as Embodiment 5, an example of a flow soldering apparatus equipped with a dross suppression jig having a heating mechanism will be described.

As shown in FIGS. 25 and 26, a heater 71 is arranged inside the dross suppression jig 31 . The temperature of the heater 71 is controlled by the heating controller 73 . The temperature of the dross suppression jig 31 is maintained at a temperature equal to or higher than the temperature of the molten solder 17 by the heater 71 .

As described in the first embodiment, the molten solder 17 jetted from the jet nozzle 19 (primary nozzle 19a) drops onto the dross suppression jig 31 after coming into contact with the printed wiring board 51 (soldering surface 51a). . It is assumed that the contact of the molten solder 17 with the printed wiring board 51 lowers the temperature of the molten solder 17 and forms semi-molten solder in which the molten solder 17 is partially solidified. Therefore, it is assumed that semi-molten sherbet-like dross comes into contact with the dross suppression jig 31 .

According to the flow soldering apparatus 1 described above, the temperature of the dross suppression jig 31 is maintained at a temperature equal to or higher than the temperature of the molten solder 17 . As a result, even if semi-molten solder contacts the dross suppression jig 31, the dross suppression jig 31, which is held at a temperature equal to or higher than the temperature of the molten solder 17, prevents the semi-molten solder. The solder can be heated to melt the semi-molten solder. As a result, the generation of sherbet-like dross in a semi-molten state can be suppressed, and further generation of dross can be suppressed.

The flow soldering apparatus 1 described in each embodiment can be combined in various ways as required.

The embodiment disclosed this time is an example and is not limited to this. The present disclosure is defined by the scope of the claims rather than the scope described above, and is intended to include all changes within the scope and meaning equivalent to the scope of the claims.

The present disclosure is effectively used in a flow soldering apparatus that jets molten solder toward a soldering object.

1 Flow soldering device, 3 Flux application unit, 5 Preheating unit, 7 Flow soldering main unit, 9 Transport mechanism, 11 Flux, 13 Preheater, 15 Solder bath, 17 Molten solder, 19 Jet nozzle, 19a Primary nozzle, 19b secondary nozzle, 21 solder bath heater, 23 impeller, 25 jet motor, 27 guide member, 27a guide groove, 31, 31a, 31b, 32, 32a, 32b, 33, 33a, 33b, 33c, 34, 34a, 34b Dross suppression jig, 37 fixing member, 39 connection member, 41 adsorption member, 43 surface treatment section, 51 printed wiring board, 51a soldering surface, 53 electronic component, 61 dross, 71 heater, 73 heating control section, LD length , WN width, Y1, Y2, Y3 arrows, HA, HB, HC, HE, L1, L2 height, FR area.

Claims

A flow soldering apparatus for soldering an object to be soldered by bringing jetting molten solder into contact with the object to be soldered,
a conveying unit that conveys the object to be soldered in a first direction;
a solder bath for storing the molten solder;
a jet nozzle disposed in the solder bath for jetting the molten solder stored in the solder bath toward the object to be soldered transported by the transport unit;
and a dross suppression jig arranged in the solder bath,
The jet nozzle has a width in a second direction that intersects with the first direction,
The length of the dross suppression jig in the second direction is longer than the width,
The dross suppression jig contacts the molten solder in a region where the molten solder jetted from the jet nozzle drops into the molten solder stored in the solder bath, and protrudes from the liquid surface of the molten solder. and a flow soldering apparatus arranged along the second direction.
The flow soldering apparatus according to claim 1, wherein the dross suppressing jig is arranged so as to float on the molten solder.
3. The dross suppression jig according to claim 1, wherein movement in said first direction and said second direction is restricted and movement in a third direction intersecting said first direction and said second direction is permitted. Flow soldering apparatus as described.
4. The dross suppression jig according to any one of claims 1 to 3, wherein a plurality of said dross suppressing jigs are arranged in said region where said molten solder jetted from said jet nozzle falls into said molten solder stored in said solder bath. Flow soldering apparatus as described.
The dross suppression jig is
a first dross suppression jig;
a second dross suppression jig disposed on the opposite side of the first dross suppression jig to the side where the jet nozzle is located;
In a state where the first dross suppression jig and the second dross suppression jig are in contact with the molten solder, the height of the second dross suppression jig from the liquid surface is the height of the first dross suppression jig. 5. The flow soldering apparatus according to claim 4, which is lower than the height from said liquid surface.
The flow soldering apparatus according to any one of claims 1 to 5, wherein the surface of the dross suppression jig is covered with a fibrous adsorption portion.
The flow soldering apparatus according to any one of claims 1 to 5, wherein the surface of the dross suppression jig is covered with a material layer having solder wettability.
The flow soldering apparatus according to claim 7, wherein the outermost surface of the material layer in the dross suppression jig includes either an iron layer or a nickel layer.
The dross suppression jig is made of stainless steel,
The flow soldering apparatus according to any one of claims 1 to 8, wherein said dross suppressing jig includes said stainless steel hollow structure.
The dross suppression jig is made of aluminum,
The flow soldering apparatus according to any one of claims 1 to 8, wherein said dross suppressing jig includes either a hollow aluminum structure or a solid aluminum structure.
The dross suppression jig is made of titanium,
The flow soldering apparatus according to any one of claims 1 to 8, wherein said dross suppressing jig includes either a hollow titanium structure or a solid titanium structure.
The flow soldering apparatus according to any one of claims 1 to 11, wherein the cross-sectional shape of said dross suppressing jig includes either circular or square.
a heating mechanism arranged in the dross suppression jig;
The flow soldering apparatus according to any one of claims 1 to 12, further comprising a heating control section for controlling the temperature of said heating mechanism.
a flux applying unit that applies flux to the object to be soldered;
and a preheating unit that heats the object to be soldered,
The flow soldering apparatus according to any one of claims 1 to 13, wherein the soldering target is conveyed by the conveying section to the flux applying section, the preheating section and the solder bath in this order.