JPH029909B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method of applying powder flux to a soldering board in an automatic soldering device, and in particular, a method of applying powder flux to a soldering board in an automatic soldering device, and in particular, a method of heaping up a stationary powder flux by moving a rod embedded in the powder flux. The present invention relates to an epoch-making method and apparatus for applying powder flux, which enables practical application of powder flux despite having an extremely simple structure in which the powder flux is brought into contact with a soldering board.

Prior Art In conventional automatic soldering equipment, a liquid flux using an organic solvent such as isopropyl alcohol is used, and the liquid flux is foamed by a flux coating device and applied to the soldering surface of the soldering board as a preliminary soldering device. Soldering was performed by heating and dipping, for example, in molten solder in a solder bath. However, in liquid fluxes containing such organic solvents,
When the organic solvent that remains on the soldering board even after preheating comes into contact with the molten solder, a large amount of flux gas is generated instantly, which obstructs the contact of the molten solder with the soldering board, resulting in poor soldering. This was particularly noticeable in soldered boards mounted with chip components that did not have through-holes. This is because if there is a through hole, flux gas can escape upward through the through hole, but if there is no through hole, the flux gas has no place to escape, and the flux gas can escape due to the strong buoyancy of the molten solder, which has an extremely high specific gravity. This was because the gas adhered to the soldering board.

Conventionally, in order to prevent soldering defects caused by this flux gas, dip-type soldering equipment used a method of tilting the soldering board when separating it from the molten solder to allow the flux gas to escape. For mounted boards, it is not possible to completely prevent soldering defects caused by flux gas using this method, and it is necessary to use a soldering method such as a jet method in combination.

Therefore, the inventor of the present application has spent many years researching an automatic soldering method and apparatus using powder flux that does not use any organic solvents instead of the liquid flux that generates flux gas as described above. Since the flux is in the form of a free-flowing powder, it has been found that it is extremely difficult to uniformly apply it to the soldering board in the same manner as liquid flux. For example, as a method for applying powder flux to a soldering board, the inventors of the present application first removed water by atomizing an aqueous liquid using an ultrasonic humidifier and deposited it on the soldering board, and then sprayed the powder flux from a nozzle. I tried spraying it on the soldering board as a powder, but
It has been found that it is difficult to uniformly adhere powder flux to a soldering board using water vapor as a medium, and it is also extremely difficult to create a jet of powder flux. In other words, it is difficult to create a low-density jet flow in which the powder flux is sufficiently diluted with air, and the amount of flux collected without adhering to the substrate is larger than that of the flux that adheres to the substrate, which is extremely inefficient. As a result, it was difficult to maintain a constant film thickness of the water or aqueous liquid (easily affected by humidity and difficult to control drying conditions), resulting in the inability to maintain a constant amount of powder flux deposited.

As described above, in the prior art, it has not been possible to uniformly and efficiently apply powder flux to a soldering board.

Purpose The present invention has been made to eliminate the drawbacks of the prior art described above, and its purpose is to bury rods near the surface of stationary powder flux filled in a powder flux tank. However, it is necessary to raise the powder flux by moving the rod horizontally at a predetermined speed, and to turn the powder flux into a jet by sequentially bringing the raised powder flux into contact with the soldering board. The purpose of the present invention is to make it possible to uniformly and efficiently apply powder flux to a soldering board with an extremely simple configuration, and thereby to enable automatic soldering by applying powder flux. To make it practical, to eliminate the generation of flux gas during the soldering process, and to enable soldering of soldered boards on which chip components are mounted even with dip-type soldering equipment. Another objective is to eliminate pollution caused by evaporation of organic solvents and to significantly reduce the risk of fire outbreak by putting powder flux into practical use. Still another object is to provide a sweeper device that smoothes the undulating surface of the powder flux after the rod is moved within the powder flux, so that the surface of the soldering board to be soldered and the powder are smoothed. The distance between the powder flux and the surface of the soldering board is always kept constant and smooth, and the variation in the amount of powder flux applied to each soldering board is minimized, and the appropriate amount of powder flux is applied to the entire surface of the soldering board. The goal is to make it possible.

Configuration In short, the method of the present invention includes disposing a powder flux tank filled with powder flux below the soldering substrate, and disposing a powder flux near the surface of the powder flux with the width of the surface to be soldered of the soldering substrate. A rod having at least the same length is buried, and by moving the rod in a horizontal direction, the powder flux above the rod is raised, and this raised part is attached to the soldering board of the soldering board. This method is characterized in that the powder flux is applied in contact with the surface. The device of the present invention (second invention) also includes a powder flux tank filled with powder flux and disposed below the soldering substrate, and a powder flux tank buried near the surface of the powder flux and filled with a powder flux tank disposed below the soldering substrate. a rod having a length at least equal to the length of the powder flux, and a drive device configured to move the rod to swell the powder flux above the rod; The present invention is characterized in that it is configured to be applied in contact with the surface to be soldered of the soldering board. Further, the device of the present invention (third invention) includes a powder flux tank filled with powder flux and disposed below the soldering substrate, and a powder flux tank buried near the surface of the powder flux and filled with a powder flux tank disposed below the soldering substrate. a rod having a length at least equal to that of the rod, a drive device configured to move the rod to heap up the powder flux above the rod, and a drive device configured to reciprocate the upper surface of the side edge of the powder flux tank. a sweeper device for smoothing the surface of the powder flux that has been rippled due to the movement of the rod; The powder flux is applied in contact with the powder flux, and the surface of the powder flux is smoothed by the sweeper device.

First, the first invention will be described. A powder flux coating device 1 according to the invention includes a powder flux tank 2, a rod 3, and a drive device 4.

The powder flux tank 2 is filled with powder flux 5 and is disposed below the soldering board 6.
As shown in FIG. 1, it is formed into a rectangular shape, and around its upper part there is a side edge 2a for preventing the powder flux 5 from spilling outside, and a rising portion 2b formed rising from the side edge. is formed. The powder flux 5 is applied to the side edge upper surface 2.
It is designed to be filled to the brim to the brim.

The rod 3 is located near the surface 5a of the powder flux 5,
For example, it is buried at a position about 10 mm below the surface, and has a length at least equal to the width of the soldering board 6, and its cross section is circular, and its diameter is set to 5 to 10 mmφ, for example. There is.

The drive device 4 moves the rod 3 to raise the powder flux 5 above the rod. An air cylinder 8 is fixed to a base 9, and the rod 3 is attached to a piston rod 10 of the air cylinder. The piston rod is slidably supported by a bearing 11 of the powder flux tank 2, and passes through the side wall 2d of the powder flux tank. A piston (not shown) fixed to a piston rod 10 is slidably housed in the air cylinder 8, and air ports _P1 and _P2 are formed in cylinder chambers on both sides of the piston, respectively. Air is supplied and discharged through air pipes 12 and 13 connected to air ports P ₁ and P ₂ . The powder flux 5 raised by the movement of the rod 3 is brought into contact with the soldering surface 6a of the soldering board 6 to apply the powder flux 5.

The piston rod 10 of the air cylinder 8 is configured to reciprocate within the powder flux tank 2 with a predetermined stroke as shown by arrows A and B in FIG. 1, and moves one stroke in the A direction or B direction. In particular, the structure is such that one application of the powder flux 5 can be completed.

Next, the second invention will be described. The apparatus according to the second invention is equipped with a sweeper device 14 in addition to the powder flux tank 2, rod 3, and drive device 4 of the first invention.

The sweeper device 14 is configured to reciprocate on the upper surface 2c of the side edge of the powder flux tank 2 to smoothen the surface 5a of the powder flux 5 which has been rippled due to the movement of the rod 3. Sweeper 1
Reference numeral 5 is formed of a round rod with a circular cross section (for example, one with a diameter of 6 to 10 mmφ), and its both ends are placed on the upper surface 2c of the side edge of the powder flux tank 2 so that it can reciprocate. A link 16 is fixed to the link 15, and is connected to a connecting rod 19 through a pin 18, and the connecting rod is connected to a crank disc 2 through a pin 20.
It is pivoted to 1. A drive shaft 22 is fixed to the center of the crank disk 21, and the drive shaft is driven by a drive device (not shown) so that the crank disk 21 rotates intermittently in the direction of arrow C. Further, the link 16 is restrained in the left-right direction by a pair of guide members 23 fixed to the side edges 2a of the powder flux tank 2, and is freely guided in the direction of advance of the soldering board 6 and in the up-down direction. ing. Sweepers 15 ride on both ends of the side edge 2a of the powder flux tank 2, respectively, and cams 25, 26 are used to escape from the surface 5a of the powder flux 5 at one end.
are attached, and stoppers 28, 29 are provided adjacent to these cams. Between these cams 25, 26 and stoppers 28, 29 are grooves 30, 3 into which the sweeper 15 can fall.
1 are formed respectively.

The cams 25 and 26 are provided one on each side of the powder flux tank 2, but their basic structure is the same as the cam 26 shown in FIG. slope 2
6a is formed, the top part 26b of which is formed in a horizontal state following the slope, and the slope 26a and the top part 2
6b is formed with a notch 26c, through which the sweeper 15 can pass in only one direction, and next to the slope 26a, a one-way opening/closing plate 32 is connected to the cam 26 by a hinge 33. It is pivotally mounted so that it can be opened only in one direction, that is, only upwardly,
The surface of the one-way opening/closing plate 32 is configured to be flush with the slope 26a.

Further, below the grooves 30 and 31, elastic bodies 35 are respectively installed to reduce the impact when the sweeper 15 descends from the cam 26. sweeper 15
The stroke of the rod 3 is equal to the length between the grooves 30 and 31, while the stroke of the rod 3 can be adjusted as appropriate depending on the length of the soldering board 6 to be soldered, and its maximum stroke is equal to the stroke of the sweeper 15. It is set almost the same as .

The powder flux replenishing device 38 is filled with powder flux 5 for replenishment, and a replenishment pipe 38a is formed below the replenishment pipe 38a. Powder flux 5 is uniformly replenished over the width of the portion excluding the side edge portions 2a, and is sent to the central portion by the sweeper 15 to be sequentially replenished.

Next, the powder flux coating device 1 according to the present invention
The manner in which this is carried out on an actual automatic soldering device 40 will be explained with reference to FIG. In the automatic soldering device 40, from the right side in the figure, an adhesive applicator 41, a preheater 4 for drying the adhesive
2. Powder flux coating device 1 and solder tank 43
The adhesive tank 44 of the adhesive applicator 41 is filled with an adhesive 45, and the nozzle 4 is filled with an adhesive 45.
6 is provided, and the adhesive 45 is sprayed upward from the nozzle in a foamed state and applied to the soldering board 6 which is conveyed by the conveyance chain 8 via the carrier 49. There is.

The preheater 42 is used to evaporate unnecessary solvent and the like in the adhesive 45 to form a thin adhesive film 45a as shown in FIG. It is set up.

The solder tank 43 has the same structure as the conventional example, and is filled with molten solder 50, and a solder heater 51 is attached to the bottom of the solder tank.

The conveyance chain 48 is formed endlessly so as to run in the direction of arrow D.

The powder flux application device 1 according to the present invention is disposed in a process after the preheater 42, and is configured to apply the powder flux 5 to the thin film 45a of the adhesive 45 formed on the soldering board 6. ing.

Next, the powder flux application method according to the present invention will be explained. A powder flux tank 2 filled with powder flux 5 is arranged below the soldering board 6, and the powder flux is applied near the surface 5a of the powder flux 5. A rod 3 having a length at least equal to the width of the surface 6a to be soldered of the soldering board 6 is buried, and by moving the rod in the horizontal direction, the powder flux 5 above the rod is heaped up. The powder flux 5 is applied by bringing the raised portion into contact with the soldering surface 6a of the soldering board 6.

Effects The present invention is configured as described above, and its effects will be explained below. In FIG. 1, a powder flux tank 2 of a powder flux application device 1 is filled with powder flux 5 in a stationary state, and when air is supplied from an air pipe 12 to an air port _P1 , the air When the cylinder 8 is actuated, its piston rod 10 moves, for example, in the direction of arrow B, and the rod 3 also moves in the same direction at the same speed. In this case, the rod 3 is placed near the surface 5a of the powder flux 5, for example at a position about 10 mm below the surface 5a, so when the rod moves, the powder flux 5 removed by the rod is removed as shown in FIG. As shown in FIG.
It will be raised by about the diameter of the rod 3, that is, about 5 to 10 mm, and this raised surface 5a
As the rod 3 moves, it moves in the direction of arrow B as shown by the imaginary line.

The present invention utilizes the swelling of the surface 5a of the powder flux 5 caused by the movement of the rod 3 to apply the powder flux 5 to the soldering surface 6a of the soldering board 6. This eliminates the need to spray the powder flux 5 as a jet fluid and apply it as in the various methods tried in the past.
This can be applied to the soldering board 6 using the following.

When the rod 3 moves in the direction of arrow B due to the operation of the air cylinder 8 and one stroke of movement is completed, the air cylinder 8 stops and the rod 3 stops below the cam 26 .

As a result of this one-stroke movement, as shown in FIG. The powder flux 5 contacts and completely adheres to the soldering board, but due to this movement of the rod 3, the surface 5a of the powder flux 5
Ripples W are formed as shown in FIG. 5, and if you try to move the rod 3 in the direction of arrow A and apply the powder flux 5 to the next soldering board 6, the desired result will not be obtained. , here the sweeper device 14 is activated. That is, when the drive shaft 22 rotates in the direction of arrow C, the crank disk 21 rotates in the same direction, and the pin 20 and connecting rod 1
9, sweeper 1 via pin 18 and link 16
5 starts moving in the direction of arrow A, and at the start of the movement, the one-way opening/closing plate 32 is pushed up, the sweeper 15 passes through the notch 26c, and moves along the upper surface 2c of the side edge of the powder flux tank 2. The rod 3 moves with its lower surface to erase the ripples W formed on the surface 5a of the powder flux 5, and the surface 5a becomes smooth in the same way as if the rod 3 had not moved at all, and the surface 5a and the soldering board 6 will be accurately determined. When the sweeper 15 advances in the direction of arrow A and reaches the position of the cam 25, it rises along the one-way opening/closing plate 32 and temporarily escapes from the surface 5a.
As shown by arrow E, it slides down the top 25b and descends into the groove 30. This state is the state shown in FIG.
As the sweeper 15 moves one stroke in the direction of the arrow A, a pool 5b is formed on the surface 5a of the powder flux 5 in which the powder flux 5 swells upward. It is moved upwardly by the cam 25, descends to the bottom of the groove 30, is received by the elastic body 35, and stops in the groove 30 when the drive shaft 22 stops without making any noise.

When the next soldering board 6 reaches above the powder flux applicator 1, air is supplied from the air pipe 13 to the air port _P2 , the air cylinder 8 is activated, and the rod 3 moves as shown in FIG. Moving in the direction A, the powder flux is applied to the soldering board 6 while raising the surface 5a of the powder flux 5, and ripples W are formed on the surface 5a again, so when the rod 3 stops, The drive shaft 22 rotates in the direction of arrow C, and the sweeper 15 moves in the direction of arrow B, eliminating the ripples and smoothing the surface 5a. When the sweeper 15 reaches the position of the cam 26, it rides on the cam along the one-way opening/closing plate 32 as shown by arrow G, slides on the top 26b, and gently descends onto the elastic body 35, and at this time, the sweeper 15 is driven The device 22 is stopped and the sweeper 15 is stopped in the groove 31. This state is the state shown in FIG.

When the next soldering board 6 reaches above the powder flux applicator 1 again, the rod 3 moves in the direction of arrow B, applies the powder flux 5 to the soldering board, and stops at the right end in the figure. However, in this case, the sweeper 15 moves in the direction of arrow A again to erase the ripples W formed on the surface 5a, thereby smoothing the surface 5a.

The above effects are repeated, but
The movement of the sweeper 15 is indicated by arrows A and B in FIG.
The motion will be as shown by E and G. By causing the sweeper 15 to perform such a movement, the pool portion 5b formed to eliminate the ripples W is caused by the sweeper 15.
The supply pipe 38a is removed from the powder flux supply device 38 by moving to the center side.
When the powder flux 5 is replenished as shown by the arrow H through the sweeper 15, it is also pushed toward the center and replenished onto the surface 5a, and the height of the surface is always equal to the side edge of the powder flux tank 2. The height is the same as that of the upper surface 2c, and therefore the surface to be soldered 6 of the soldering board 6
The distance to a is always kept the same and smooth.

Next, the powder flux coating device 1 according to the present invention described above will be explained as one step in the automatic soldering device 40. In FIG. 3, the transport chain 48 moves a plurality of carriers 49, and transports, in the direction of arrow D, a plurality of soldered boards 6 supported by the carriers and mounted with, for example, electronic components 7 with lead wires 7a. In the adhesive applicator 41, an adhesive 45 is sprayed upward from a nozzle 46 in a foamed state by a drive device (not shown), and the adhesive 45 is applied to the surface 6a of the soldering board 6 to be soldered. The state shown in FIG. 6 changes to the state shown in FIG. 7. And soldering board 6
When the adhesive reaches the upper part of the preheater 42, the solvent in the adhesive evaporates by being preheated and dries to form a thin film 45a of the adhesive 45, which has a very high viscosity. becomes. When the soldering board 6 reaches above the powder flux applicator 1 and the conveyance chain 48 stops, the air cylinder 8 of the drive device 4 is operated as described above to move the rod 3 and apply the powder. body flux 5
is applied to the thin film 45a, and then the sweeper device 14 is operated to smooth the surface 5a of the powder flux 5, and the soldering board 6 is conveyed to the solder tank 43 by the conveyance chain 48, and the molten solder 50 is applied to the thin film 45a. The surface 6a to be soldered comes into contact with the soldering surface 6a, and soldering is performed.
In this case, the powder flux 5 does not use any solvent, so unlike the case of conventional liquid flux, almost no flux gas is generated, and it is used in the dip-type solder bath 43 as shown in the figure, when chip components are mounted. Soldered board (not shown)
Also, complete soldering is performed.

When the soldering is completed in this way, the soldering board 6 is lifted again by the conveyance chain 48 and carried out from the solder tank 43, and is removed from the conveyance chain 48 to become a completed product. In the illustrated embodiment, the rod 3 of the powder flux applicator 1 is configured to reciprocate in the same direction as the conveyance direction of the soldering board 6, but this is different from the configuration in which the rod 3 of the powder flux applicator 1 reciprocates in the direction perpendicular to the conveyance direction. It goes without saying that the drive device 4 and the mechanism for driving the sweeper 15 of the sweeper device 14 are not limited to those shown in the drawings. Obviously, various modifications may be made.

Note that the adhesive 45 is nonflammable, nonvolatile,
Those that are non-corrosive, non-toxic, do not produce toxic substances through thermal decomposition, etc., and have powder adhesion are preferred, such as methyl ester of hydrogenated rosin or an aqueous dispersion of hydroabiethyl alcohol. is suitable.

Effects Since the present invention is configured and operates as described above, a rod is buried near the surface of the stationary powder flux filled in a powder flux tank, and the rod is moved horizontally at a predetermined speed. By moving the powder flux to the soldering board, the powder flux is raised, and this raised powder flux is brought into contact with the soldering board one after another.Therefore, there is no need to turn the powder flux into a jet, and the process is extremely simple. This configuration provides the effect that the powder flux can be uniformly and efficiently applied to the soldering board. As a result, automatic soldering by applying powder flux can be put to practical use, eliminating the generation of flux gas during the soldering process, and even using a dip-type soldering device to solder a soldered board on which chip components are mounted. It has the effect of making it possible. Further, by putting powder flux into practical use, it is possible to eliminate pollution caused by evaporation of organic solvents, and the risk of fire outbreak can be significantly reduced. Furthermore, a sweeper device is provided to smooth the undulating surface of the powder flux after the rod is moved within the powder flux, so that the soldering surface of the soldering board and the surface of the powder flux can be smoothed. It is possible to keep the distance constant and smooth at all times, and it is possible to extremely minimize variations in the amount of powder flux applied to each soldering board. The effect is that it can be applied.

Example 1 In the powder flux applicator 1 according to the present invention, by using the adhesive 45 having the composition shown below, the powder flux 5 can be sufficiently applied to the soldering board 6, and it is extremely effective in soldering. It was found that good wettability was obtained, and soldering using powder flux could be put to practical use.

Methyl ester of hydrogenated rosin (sticky substance)...
...2% by weight Isopropyl alcohol (solvent)...20% by weight Dialkylsulfosuccinic acid (wetting agent) 10
% aqueous solution...1% by weight Water (non-flammable diluent)...77% by weight Example 2 Similarly, in the powder flux coating device 1 according to the present invention, the following composition was used as an adhesive 45 having a different composition. Even with this, very good adhesion and solderability of the powder flux 3 were obtained.

Hydroabiethyl alcohol (sticky substance)
...3% by weight Butyl cellosolve (solvent)...40% by weight Water (nonflammable diluent)...57% by weight

[Brief explanation of drawings]

The drawings relate to embodiments of the present invention; FIG. 1 is a perspective view of a powder flux application device, FIG. 2 is a perspective view of a cam and a one-way opening/closing plate, and FIG. 3 is a perspective view of a powder flux application device according to the present invention. FIG. 4 is a schematic side view of an automatic soldering device using a coating device; FIG. 4 is a vertical cross-sectional view showing a state in which powder flux is applied to a soldering board by moving a rod to build up powder flux; FIG. 5 6 is a longitudinal cross-sectional view showing the state in which ripples formed on the surface of the powder flux are smoothed out by a sweeper device, FIG. 6 is a side view of a soldered board on which electronic components are mounted, and FIG. 7 9 is a side view showing a state in which a thin film of adhesive is formed on the surface to be soldered of a soldering board, FIG. 8 is a side view showing a state in which powder flux is applied to the soldering board shown in FIG. The figure is a line diagram showing the movement of the sweeper, Fig. 10 is a longitudinal cross-sectional view showing the movement of the sweeper at the end of the stroke and the powder flux replenishment state, and Fig. 11 is a diagram showing the ripples on the surface of the powder flux by the sweeper. Fig. 12 is a longitudinal sectional view showing the movement of the sweeper at the right end of the stroke in the drawing, and Fig. 13 shows the state in which the sweeper is erasing the ripples on the surface of the powder flux. FIG. 1 is a powder flux application device, 2 is a powder flux tank, 2c is a side edge upper surface, 3 is a rod, 4 is a drive device, 5 is a powder flux, 5a is a surface, 6 is a soldering board, and 6a is a coating. The soldering surface 14 is a sweeper device.

Claims (1)

[Scope of Claims] 1. A powder flux tank filled with powder flux is disposed below the soldering board, and near the surface of the powder flux is at least as wide as the width of the surface to be soldered of the soldering board. burying rods having the same length and moving the rods in a horizontal direction to raise the powder flux above the rods;
A method for applying powder flux, characterized in that the powder flux is applied by bringing the raised portion into contact with the surface to be soldered of the soldering board. 2. A powder flux tank filled with powder flux and arranged below the soldering board; and a rod buried near the surface of the powder flux and having a length at least equal to the width of the soldering board. , a driving device configured to move the rod to swell the powder flux above the rod, and to transfer the powder flux swelled up by the movement of the rod to the surface to be soldered of the soldering board. 1. A powder flux application device characterized in that the powder flux application device is configured to apply the powder flux by bringing it into contact with the powder flux. 3. A powder flux tank filled with powder flux and arranged below the soldering board; and a rod buried near the surface of the powder flux and having a length at least equal to the width of the soldering board. a driving device configured to move the rod to raise the powder flux above the rod; and a drive device that reciprocates on the upper surface of the side edge of the powder flux tank to cause the powder flux to ripple due to the movement of the rod. a sweeper device for smoothing the surface of the powder flux; the sweeper device applies the powder flux that has risen due to the movement of the rod in contact with the surface to be soldered of the soldering board; 1. A powder flux application device, characterized in that the device is configured to smooth the surface of the powder flux.