JPH06198429A - Flux applying device - Google Patents

Abstract

PURPOSE:To spread a flux in the state of bubbles to the detailed parts of a soldering surface so that the flux can be applied uniformly on a circuit board by segmenting the inside of a nozzle body by means of partition plates to plural bubbling chambers. CONSTITUTION:The inside of the nozzle body 5 is formed by segmenting the inside to the plural bubbling chambers 10 by means of the partition plates 9. The bubbles generated from a bubbling pipe 6 are parted within the respective bubbling chambers 10 segmented to a plurality, by which the bubbles are led as they are to bubbling jet ports 7 provided on the upper side of the respective partitioned bubbling chambers 10. As a result, the bubbles gushing out of the bubbling jet ports 7 are ejected as uniform bubbling of a small variation in density. The height of the bubbles of the flux bubbled from the bubbling jet ports 7 is thus maintained constant and the flux is uniformly applied on the soldering surface of the circuit board 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux coating device in a circuit board automatic soldering process.

[0002]

2. Description of the Related Art There is an automatic soldering apparatus for transporting a circuit board and soldering the soldered surface of the circuit board, for example, through a solder bath in which molten solder water is jetted.

This automatic soldering apparatus is provided with a flux applying apparatus for applying flux to the soldering surface of a circuit board to be transported as a pretreatment for performing the soldering processing.

In general, by applying flux to the soldered surface, the oxide film formed on the soldered portion is removed, and electrical contact failure between the solder after soldering and the soldered portion is prevented.

It is prevented that an oxide film is formed again before being transported to the solder bath.

The inclusion of pine or the like (solid content) improves the adhesion with solder.

It is for giving the following effects.

Conventionally, this flux coating apparatus is arranged in parallel below the circuit board that is conveyed with the soldering surface facing down toward the solder bath, on the front side in the transport direction of the solder bath via a substrate preheating device. The nozzle body is provided at a position where the soldered surface of the circuit board to be conveyed passes closely above the nozzle body, in which the flux is foamed and jetted.

Specifically, a nozzle body projecting above the level of the flux liquid surface is provided inside a flux tank containing the flux, and a foam tube made of a porous material that serves as a bubble generating portion is installed inside the nozzle body. At the same time, pressurized air can be supplied to the foam tube, and a foam jet port having a lateral width corresponding to the soldered surface width is provided at the upper end of the nozzle body.

Therefore, the flux is foamed from the foaming tube by the pressurized air sent to the foaming tube serving as the bubble generating portion, jets out from the foaming jet port at the upper end, and passes above the foaming jet port in a close state. The circuit board is conveyed to the soldering surface on the lower surface of the circuit board so that the foamed flux is contacted and applied.

[0011]

Such a foaming jet method has excellent work efficiency and is suitable for automation as compared with a method of immersing a circuit board in a flux, and the foaming method allows bubbles to penetrate into details. This is a very excellent application method in which flux is applied to the details due to the phenomenon of bubbles that have entered and the soldered surface is evenly wetted. As described above, the foaming jet method is a very excellent method, but in order to make full use of this characteristic, it is desirable to jet a foaming flux that becomes uniform and fine bubbles. That is, it is desirable to apply the flux uniformly on the soldered surface with a uniform foam diameter.

On the other hand, in general, pressurized air is sent into the hollow portion of a foamed tube having a substantially cylindrical cross section and made of a porous material, which is a foam generating portion, and bubbles of a predetermined size (flux) generated in this foamed tube. Rises in the flux toward the foam jet nozzle at the upper end, but since the fluid pressure of the flux (internal pressure) is lower in the upper part than in the lower part, the bubble diameter when exiting the foam tube was almost the same. However, there is also a problem that the bubble diameter is likely to be different as it rises because the water pressure gradually decreases due to the difference in water pressure between the bubbles ejected from the lower side of the foam tube and the bubbles from the upper side. In order to avoid this, it is conceivable to set the bubbling position, that is, the flux immersion position of the bubbling tube to a position near the liquid level, but if it gets too close to the liquid level, the problem that the bubbling is not stable will occur. , Is not a solution.

On the other hand, commercially available rosin flux is
It contains 15 to 30% by weight of rosin-based resin and is widely used because it has a relatively good foaming property. Recently, however, soldering of surface-mounted components on circuit boards has increased. If the amount of rosin-based resin in the flux is large, the amount of flux residue due to the fixed amount of the flux is large, which is time-consuming for cleaning and is not environmentally preferable due to the heavy use of CFCs and the like. There is also a need for a low residue flux containing a rosin-based resin in a low concentration of 15% by weight or less for the purpose of eliminating cleaning.

However, in the flux applying method using the low residue flux, the foaming is apt to be deteriorated due to the decrease in viscosity. Therefore, in the flux applying method using the foaming, the flux is not surely applied to the circuit board, and as a result, the good result is obtained. There is also a problem that excellent solderability cannot be obtained.

Further, in the conventional flux device, as shown in FIGS. 7 and 8, the opposing peripheral wall 23 of the nozzle body 22 arranged above the foaming tube 21 serving as a bubble generating portion is provided in a V shape to rise. The bubbles are collected in the foaming jet port 24 so that the jetting height can be obtained above the jet port. However, the nozzle body 2
By making the opposing peripheral wall 23 of 2 into a V shape, it is possible to make sure that the opposing peripheral wall 2
Although it is possible to obtain the height of the bubbles ejected above the foaming jet port 24 at the upper end of 3, the bubbles that rise and collide with the inclined peripheral wall 23 are collided as shown by the arrows in FIG. Turbulent flow and stagnation at this peripheral wall portion, this turbulent bubble does not reach the foaming jet port 24 at the upper end easily, so bubbles tend to pop up and become large, and rise straight without colliding with the opposing peripheral wall 23 The foam diameter of the guided foam is remarkably different depending on the foam and the turbulent flow, and there is a problem that the above-mentioned uniform foam cannot be obtained.

Further, since the nozzle body 22 is formed by the elongated peripheral facing peripheral wall 23 along the width direction of the circuit board P, the bubbles Bu generated from the foam tube 21 which is the bubble generating portion is generated in the nozzle body 22. The fluctuation of the bubble Bu itself occurs due to the flow of the internal flux liquid and the change of the water pressure, and in the process of the bubble Bu rising in the flux liquid, the bubble Bu does not rise right above but rises obliquely and varies widely. The phenomenon of rising may occur, which means that the nozzle body
The larger the internal volume of 22, the more likely it is to appear.

For this reason, a dense and dense area of the bubbles Bu is generated inside the nozzle body 22, and the dense bubbles Bu collide with each other to cause a popping phenomenon. As a result, the particles of the bubbles Bu become large, Bubble Bu with problem that diameter is hard to be constant
There is a problem that the height of the foaming spouting from the foaming jet port 24 becomes uneven due to the sparse and denseness of.

The present invention pays attention to such a problem, eliminates the variation in the foam diameter caused by the phenomenon such as the bubble popping due to turbulent flow or low residue flux, makes the foam diameter almost uniform, and makes the height due to foaming almost uniform. It is an object of the present invention to provide a flux coating device that can be kept constant.

[0019]

The gist of the present invention will be described with reference to the accompanying drawings.

The flux 2 is applied to the soldering surface 1A of the circuit board 1 which is transported as a pretreatment for soldering the circuit board 1.
1. A flux applying apparatus in a process of automatically soldering a circuit board for applying a flux, wherein a bubble generating section 6 for foaming the flux 2 is arranged in a flux tank 3 containing a flux liquid, and the bubble generating section 6 is pressurized. A gas is introduced to cause bubbles to be generated from the bubble generating section 6, and a nozzle body 5 composed of guide peripheral walls 4 facing each other in a frame shape for guiding the foamed flux 2 is arranged above the bubble generating section 6. The guide peripheral wall 4 of the nozzle body 5 is provided with a foaming jet port 7 for jetting the foaming flux 2 above the nozzle body 5, and the opening width L of the foaming jet port 7 in the carrying direction of the circuit board 1 is predetermined. Is set to a jet width L at which the height of bubbles is obtained, and an inlet 8 for guiding the foamed flux 2 generated from the bubble generator 6 is provided in the lower portion of the nozzle body 5, and the circuit of the inlet 8 is On board 1 Feeding set direction of the opening width S in the narrow jet width L equal to or width of the foam jet port 7 to form a guide jacket 4 of the nozzle body 5, and the nozzle body 5
A plurality of partition plates 9 are provided in the interior of the nozzle substantially at right angles to the width direction of the circuit board 1, and the interior of the nozzle body 5 is partitioned into a plurality of foaming chambers 10 by the partition plates 9. The present invention relates to a flux applying device.

[0021]

The inlet 8 for guiding the foamed flux 2 generated from the bubble generator 6 is provided in the lower part of the nozzle body 5, and the opening width S of the inlet 8 in the carrying direction of the circuit board 1 is set to the foam jet port. 7 is provided to be equal to or narrower than the jet flow width L to form the guide peripheral wall 4 of the nozzle body 5, and a plurality of partition plates 9 are provided inside the nozzle body 5 substantially orthogonal to the width direction of the circuit board 1. This partition plate 9 is provided at intervals.
By forming the interior of the nozzle body 5 into a plurality of foaming chambers 10 by means of, the turbulent flow of the bubbles 12 is suppressed along the foaming chambers 10 partitioned by the guide peripheral wall 4 and the partition plate 9, and the nozzle body is 5 to the foaming jet port 7 and the foaming flux 2 having a uniform bubble diameter is ejected.

Further, by partitioning the inner volume of the nozzle body 5 into small parts by the partition plate 9, the blowing height of the bubbles 12 in the width direction of the circuit board 1 can be jetted substantially constant.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A schematic structure of this embodiment will be described with reference to FIGS.

Nozzle body 5 protruding upwards above the level of the flux liquid in a flux tank 3 containing the flux 2.
Is arranged in the width direction of the circuit board 1 which is conveyed and passed over,
A foam tube 6 made of a porous material, which serves as a bubble generating part for foaming and jetting the flux 2 through the lower inlet 8 of the nozzle body 5.
The soldered surface 1 on the lower surface side of the circuit board 1 which is arranged above and which carries and passes the foaming jet port 7 formed at the upper end of the nozzle body 5.
It is located near A.

In this embodiment, the nozzle body 5 is constructed as follows.

The lateral width of the circuit board 1 is approximately the same as that of the circuit board 1, and the guide peripheral wall 4 facing the direction of carrying the circuit board 1 is formed in a box-like body having upper and lower openings. It is formed in an inverted V shape so that the facing interval is wide.

The long mouth-shaped upper opening is used as a foaming jet port 7, and the opening width L of the circuit board 1 in the carrying direction is designed to be an appropriate jetting width required as a foaming region.

The long lower opening is used as the introduction port 8 and is formed narrower than the opening width L of the foam jet port 7.
It is arranged so as to face only the foaming range of the upper part of the foam tube 6 so as to introduce only the flux 2 foamed from the upper foaming range of the round tubular foam tube 6 serving as the bubble generating part.

Further, as shown in FIG. 1, a large number of partition plates 9 are provided inside the nozzle main body 5 substantially perpendicularly to the width direction of the circuit board 1 at predetermined intervals and arranged in parallel vertically. A plate 9 divides the interior of the nozzle body 5 into a plurality of foaming chambers 10 to divide the foaming jet port 7.

Therefore, the guide peripheral wall 4 of the nozzle body 5 is
Since they are provided in a substantially inverted V shape in which the facing interval on the upper side is slightly widened, a part of the foaming that occurs in the case of the conventional C-shaped opposed peripheral wall 23 opposite to this as shown in FIG. 8 is formed. It is possible to suppress a phenomenon in which the flux 2 collides with the opposing peripheral wall 23 and bubbles caused by the turbulent flow burst and become large.

From the foam jet port 7, the foam flux 2 having a uniform bubble diameter can be jetted.

Further, the inside of the nozzle body 5 is divided into a plurality of foaming chambers 10 by the partition plate 9 to form a plurality of bubbles 12 generated from the foaming pipe 6 which is a bubble generating portion. By sorting inside the foaming chambers 10, it is possible to directly guide the foams to the foaming jet ports 7 provided on the upper side of each of the partitioned foaming chambers 10, and thereby the bubbles 12 jetted from the foaming jet ports 7 can be uniformly distributed with little density. The bubbles 12 of the flux 2 foamed from the foaming jet port 7 can be maintained at a substantially constant height, and the flux 2 is evenly applied to the soldered surface of the circuit board 1. It becomes possible to do. In this case, the vertically arranged partition plates 9 prevent the foamed flux 2 from flowing in the lateral direction, guide the rise of the foamed flux 2, and introduce the inlet 8
The foaming diameter is made uniform by making the distance from the above to the foaming jet port 7 as constant as possible.

Moreover, in this embodiment, not all of the foaming flux 2 generated from the upper part and the lower part of the foaming pipe 6 is introduced, but only the foaming range of the upper part having a small water depth difference is introduced. It is possible to eliminate the non-uniformity and to obtain more uniform foaming.

Reference numeral 11 in the drawing is a frame body, and this frame body 11
The foam tube 6 which is the bubble generating part is attached to the frame body 11, and the nozzle body 5 is mounted on the frame body 11 so as to mount the foam tube 6 and the nozzle body 5 together with the frame body 11 inside the flux tank 3. is doing.

FIGS. 4 and 5 show a second embodiment. In this embodiment, the jet width L1 of the bubbling jet port 7 is wide, and the introduction port 8 provided in the nozzle body 5 is bubbling. A guide peripheral wall of the nozzle body 5 is set so that the opening width S1 of the introduction port 8 in the carrying direction of the circuit board 1 is set to be slightly narrower than the opening width L1 of the foaming jet port 7 in accordance with the outer dimensions of the pipe 6. 4 is formed in an inverted V shape.

In addition, a large number of partition plates 9 are arranged in the nozzle body 5 substantially perpendicular to the width direction of the circuit board 1 at predetermined intervals and arranged in the vertical direction, and in the conveying direction of the circuit board 1. A vertical guide wall 4A is arranged along the width direction of the circuit board 1 between the guide peripheral walls 4 arranged to face each other, and the inside of the nozzle body 5 is surrounded by the partition plates 9 and the guide wall 4A. Formed by dividing into a plurality of foaming chambers 10A in two rows,
The foaming jet ports 7 are formed by dividing the foaming chamber 10A in units of two rows.

Therefore, as compared with the first embodiment described above, it is possible to increase the amount of foaming bubbles 12 and to eject the bubbles having a substantially constant diameter and a substantially constant foaming height.

FIG. 6 shows a second embodiment. In this embodiment, as described above, the foaming flux 2 is introduced from the introduction port 8 in a state where there is as little water depth difference as possible in the foaming range of the foaming tube. The flat foam part 6A made of a porous material is provided above the frame body 11 having an open top as a bubble generating part, and the foam part 6A has a flat shape. A frame-shaped nozzle body 5 composed of a vertical wall is arranged on the upper side, and the inside of the nozzle body 5 is divided by a partition plate 9
Is formed by partitioning into a plurality of foaming chambers 10B.

Therefore, it is possible to obtain the same effect as that of the above-described embodiment, to keep the water depth with the flux liquid surface substantially constant, and to foam the foam at the foam jet port 7 provided in the nozzle body 5. It is possible to keep the diameter constant more than in the above-mentioned embodiment.

The present invention is not limited to the above-described embodiment, but the shape of the nozzle body 5 and the opening angle of the opposed peripheral wall 4 having an inverted C-shape can be appropriately designed. Even if it is not opened, one side may be vertical and only one side may be opened. Regarding the arrangement of the lower inlet 8 and the bubble generating part 6, the bubble generating part 6 can be used without being connected to the bubble generating part 6. You may arrange | position in the state which adjoined so that the foaming flux 2 could be introduced.

[0041]

Since the present invention is configured as described above, it is possible to suppress the turbulence phenomenon and the like as compared with the conventional one, and it is possible to maintain a substantially uniform foam diameter and to keep the ejected foam substantially constant. By doing so, it is possible to provide a flux applying device that can apply the flux uniformly to the circuit board.

[Brief description of drawings]

FIG. 1 is an explanatory front sectional view of a first embodiment.

FIG. 2 is a schematic perspective view of a first embodiment.

FIG. 3 is an explanatory side sectional view of the first embodiment.

FIG. 4 is a schematic perspective view of a second embodiment.

FIG. 5 is an explanatory side sectional view of a second embodiment.

FIG. 6 is a schematic perspective view of a third embodiment.

FIG. 7 is a schematic configuration perspective view of a conventional example.

FIG. 8 is an explanatory side sectional view of a conventional example.

[Explanation of symbols]

 1 Circuit Board 1A Soldered Surface 2 Flux (Foaming Flux) 3 Flux Tank 4 Guide Peripheral Wall 5 Nozzle Body 6 Bubble Generating Part (Foaming Pipe) 7 Foaming Jet Inlet 8 Inlet

Claims (1)

[Claims] 1. A flux applicator in an automatic soldering process of a circuit board for applying flux to a soldering surface of a circuit board transported as a pretreatment for soldering the circuit board, the flux containing a flux liquid. A bubble generating part for foaming the flux is arranged in the tank, and pressurized gas is introduced into the bubble generating part to generate bubbles from the bubble generating part, and the foamed flux is guided to the upper part of the bubble generating part. A nozzle body composed of guide peripheral walls facing each other in a frame shape is provided, and a foam jet nozzle for jetting upward a foam flux is provided on the guide peripheral wall of the nozzle body, and the circuit of the foam jet nozzle is provided. The width of the opening of the substrate in the transport direction is set to the jet width that gives a predetermined bubble height, and
An introduction port for guiding the foamed flux generated from the bubble generation part is provided in the lower part of the nozzle body, and the opening width of the introduction port in the carrying direction of the circuit board is made equal to or narrower than the jet width of the foaming jet port. The guide peripheral wall of the nozzle body is set by setting a plurality of partition plates at intervals inside the nozzle body substantially orthogonal to the width direction of the circuit board. A flux applicator characterized by being formed by dividing the interior into a plurality of foaming chambers.