JPH02187261A - Solder vessel - Google Patents

Abstract

PURPOSE:To minimize the change of wave height, to maintain its stable shape and to prevent defective solder by feeding molten solder to a solder storage part from solder nozzles and forming blowing-up waves on the solder surface in the storage part. CONSTITUTION:The molten solder 10 is once supplied to the inside of the solder storage part 6 stored therein through the solder nozzles 2 from the inside of a tower 1 by operation of a feed mechanism. After being stored, when the feed pressure of the solder is further increased, according to the solder inflow pressure from the nozzle 2, the blowing-up waves 13-16 swollen from the solder surface 11 in the storage part 6 are then formed thereon. Accordingly, a printed board 12 is made to travel slightly above the solder tower 1 and the near surface of the board 12 is brought into contact with the blowing-up waves 13-16, by which soldering is performed. The solder in the storage part 6 is swollen by receiving the inflow pressure from the nozzle 2 and as a result, the blowing-up waves 13-16 formed in the solder tower 1 are produced and the change of wave height is slight exceedingly and the stable shape is always maintained and in addition, every waveform is made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a solder tank that is mainly incorporated into an automatic soldering device for soldering printed circuit boards.

(Prior Art) Conventionally, the soldering process for printed circuit boards has been carried out using automatic soldering equipment that automates a series of processes such as preheating, immersion in flux, soldering, and cooling. ing.

The solder tank incorporated in this automatic soldering device is a print machine that sprays molten solder in the solder tank from a blowing hole at the top of the tank, and directs the solder jet to run horizontally or with a gentle slope in the direction E of the tank. A so-called jet type solder bath, which is brought into contact with the bottom surface of the substrate, is often used. Conventionally, as a solder tank of this type, one in which several or several blowing ports are formed in a row in the upper part of the solder tank and several rows of these is often used.

(Problem to be Solved by the Invention) However, in conventional jet-type solder baths, the jet of molten solder ejected from the nozzle is directly brought into contact with the bottom surface of the printed circuit board, so the height of the solder jet is limited. It easily fluctuates due to changes in solder feeding pressure, making it difficult to obtain a solder jet with a stable height.

Furthermore, the height of the solder jet has a strong correlation with the dimensional accuracy of the nozzle, and in a solder bath with a nozzle with normal machining accuracy, it is difficult to form solder jets of uniform height for all the nozzles. was difficult.

For this reason, defects such as so-called solder fog, in which molten solder adheres partially but excessively to the lower surface of the printed circuit board, may occur.

In addition, conventional jet-type solder baths had a structure that continuously jetted out a large amount of molten solder and collected most of the solder jet directly into the solder bath without making direct contact with the printed circuit board. The oxidation of the entire molten solder progresses rapidly, and the amount of oxidized solder that must be discarded is extremely large, which poses a major economic problem.

The present invention was made based on such circumstances.

The purpose of this is to provide a solder tank that can form a uniformly high and always stable blown-up wave of molten solder, and that generates extremely little oxidized solder during the soldering process. It is in.

(Means for Solving the Problems) The solder tank of the present invention includes a solder spout at the top of the tank, a solder reservoir above the spout, and molten solder is supplied to the solder from the solder spout. The present invention is characterized in that it includes a solder feeding mechanism that feeds solder to a reservoir and forms blown-up waves on the surface of the solder within the reservoir.

That is, the solder tank of the present invention is provided with a solder nozzle whose shape is similar to a conventional solder nozzle at the top of the tank, and furthermore, a solder reservoir is provided above the solder nozzle, and the solder reservoir is opened by operating the solder feeding mechanism. After the solder 11 is temporarily stored in the solder, waves are formed on the surface of the solder to perform soldering.

Usually, the solder nozzles are arranged in a row of several to several pieces in the longitudinal direction of the solder tank (perpendicular to the running direction of the printed circuit board), and in the width direction of the tank (in the direction perpendicular to the running direction of the printed circuit board). direction), creating a series of spouts.

The solder nozzle may consist of a plurality of nozzles located on the same horizontal plane at its upper end, and the distance between the nozzle, the end, and the solder surface in the solder reservoir may all be the same;
Further, it may be made up of a plurality of nozzles whose upper ends are located on different horizontal planes, and the distance between the upper ends of the nozzles and the solder surface in the solder reservoir portion is different from each other.

Furthermore, the nozzles are not limited to nozzles all having the same diameter, but may be composed of several types of nozzles having different diameters.

The solder spout communicates with the inside of the solder tank, and also communicates with the blades of the solder feeding mechanism through there.

The solder feeding mechanism may be a conventionally used feeding mechanism including a motor, an impeller, a connecting member thereof, a flow path for molten solder, and the like.

In addition, the solder reservoir part is configured to apply molten solder to the upper side of the solder spout, for example, from 3 to 50 mm, preferably from 1 to 25 ++.
Any structure may be used as long as the solder can be stored at a depth of +-.For example, the solder nozzle may be constructed of a plurality of sides and plates extending diagonally upward from the peripheral edge of the plate forming the solder spout or its vicinity.

(Function) In the solder tank of the present invention, by operating the feeding mechanism, molten solder is once supplied from the inside of the tank through the solder spout into the solder reservoir and stored there (note that the solder feeding pressure is released). do not.). After the solder has accumulated, when the supply pressure of the solder is further increased, a bulging wave is formed on the solder surface in the reservoir according to the solder inflow pressure from the nozzle. Therefore, soldering can be carried out by running the printed circuit board slightly above the solder bath and bringing the lower surface of the circuit board into contact with the above-mentioned blown-up waves.

The blown-up waves formed in this solder tank are caused by the solder in the reservoir bulging in response to the inflow pressure from the nozzle. Therefore, in the conventional jet-type solder tank, the solder is blown directly upward from the nozzle. Compared to a jet stream, fluctuations in wave height are very small and a stable shape can always be maintained, and the waveforms can also all be uniform.

The shape and height of the blown-up wave are related not only to the supply pressure but also to the position and shape of the solder nozzle. The higher the upper end of the nozzle is and the smaller the distance between it and the solder surface in the reservoir, the higher and sharper the jet waves will be. The upwelling waves become lower and more gradual. Therefore, if a plurality of solder nozzles are arranged on a horizontal plane in which the heights of the nozzle tops are sequentially different with respect to the running direction of the printed circuit board, that is, the top end of the nozzles and the solder surface in the solder pool can be connected in the same direction. If the intervals are made to be different sequentially, it is possible to form erupting waves that have different heights in the same direction, thereby achieving better soldering.

Furthermore, under a solder supply pressure above a certain level, the larger the diameter of the solder nozzle, the higher the wave will be, and conversely, the smaller the diameter of the solder nozzle, the lower the wave will be. Therefore, by sequentially increasing the diameter of the solder spout with respect to the running direction of the printed circuit board, it is possible to form blown-up waves having successively different heights in the direction, thereby achieving better soldering.

In addition, as another aspect, the solder tank of the present invention is configured to form blown-up waves on the surface of the molten solder stored in the upper part of the tank and bring the molten solder into contact with the printed circuit board.

Unlike conventional jet-flow solder tanks, it does not have a structure in which a large amount of molten solder is continuously poured out of the tank and then collected. Therefore, the total amount of solder required for the soldering process is very small, and the amount of oxidized solder that should be discarded at the reuse stage is also reduced.

(Example) The present invention will be explained in detail below.

Example 1 As shown in Fig. 1 and Fig. 2, one half of one tank 1 of this embodiment
has a horizontal upper plate lO on its top.

The upper plate 10 is provided with several rows of solder nozzles 2, all of which have the same diameter, in the longitudinal direction and a total of three rows in the width direction. The direction in which the nozzles 2 are arranged coincides with the direction perpendicular to the running direction of the printed circuit board 12 (direction of arrow X in the figure).

Further, the upper ends 7 of the nozzle ports 2 are all located on the same horizontal plane a, and the distances from the solder surface 11 in the reservoir 6 described below are all equal.

Further, the solder tank 1 is formed by surrounding the solder plate 10 with the side plates 3, 4, 5, . The solder 20 that has flowed in is designed to accumulate. As shown in FIG. 2, the side plates 3, 4, etc. are fitted with their lower parts into the pockets 8, 9, respectively, and are slidably movable in the direction of the arrows ±P force ±Q force in the figure, so that the reservoir portion The surface water level of the solder 20 in 6 can be adjusted as desired.

Further, the solder tank l is connected to a solder feeding mechanism (not shown) consisting of an impeller, a motor, etc. When the mechanism is operated, the molten solder is fed under pressure, passes through the jets [12... It is designed to be supplied internally.

Due to the free rotation of the feeding mechanism, the molten solder 10 is supplied from the inside of the tank 1 through the spout 2 to the reservoir 6, and is accumulated there. The direction of arrow f in the figure indicates the flow of solder. Thereafter, when the solder feeding pressure is further increased, the solder surface 11 within the reservoir 6 bulges, forming blown-up waves 13 as shown in the figure. By running the printed circuit board 12 slightly above the tank 1, the lower surface of the circuit board 12 is soldered.

All the eruption waves 13... maintained a constant height, were always stable, and were uniform in shape and height. Furthermore, during soldering using this solder tank, the amount of oxidized solder generated was significantly smaller than in the conventional process.

Example 2 As shown in FIG. 3, the solder tank l of this embodiment is.

The top plate 10 has a top surface with three steps, and each longitudinal row of nozzles 2... has a different length intersection r, lt, and . Horizontal plane a 1 * whose height is sequential in the running direction (X direction)
2 + and a3, so that the distance between the upper end 7 and the solder surface 11 in the reservoir 6 is sequentially arranged in the X direction.

The other configurations are the same as in the first embodiment.

In addition to the same functions and effects as in Example 1, the solder bath of this embodiment forms solder jet waves 14, 15 and 16 whose heights are successive in the board running direction (X direction), and the solder on the board is I was able to perform the attachment more smoothly.

Embodiment 3 As shown in FIG. 4, the solder bath 1 of this embodiment has nozzle holes 2 in each row in the longitudinal direction having diameters φ1 and φ2 that are sequentially arranged in the running direction of the printed circuit board (arrow X direction). ．． and φ
The solder tank has the same configuration as the solder tank of Example 1, except that the solder tank has the same structure as the solder tank of Example 1.

Similarly to the second embodiment, the solder tank l of this embodiment also has solder spouting waves 14, 15 and 15 whose heights are sequentially arranged in the X direction.
, and 16 were formed, and the soldering of the board 12 could be carried out very successfully.

(Effects of the Invention) As explained above, in the solder bath of the present invention, the formed solder jet wave has a stable shape with very small fluctuation in wave height compared to the solder jet flow in a conventional jet solder bath. In addition, the waveform becomes very uniform, so problems such as half 81 curling do not occur, and a very convenient soldering that has never been seen before can be achieved.

Furthermore, the solder tank of the present invention, like the conventional jet-flow solder tank,
Since the structure is not designed to continuously pour a large amount of molten solder out of the tank and collect it, the total amount of solder required for soldering is very small, and oxidized solder that should be discarded at the reuse stage is removed. The amount generated is also very small.

Moreover, in the solder tank of the present invention, by arranging the position or diameter of the upper end of the nozzle to be sequential in the running direction of the printed circuit board, it is possible to form a blown-up wave having a height or a specific diameter in the same direction. Better soldering is achieved.

[Brief explanation of the drawing]

1 is a perspective view showing the upper part of the solder tank according to the first embodiment of the present invention; FIG. 2 is a sectional view taken along the line II-■ of the solder tank in FIG. 1; and FIG. 4 is a cross-sectional view showing the upper part of the solder tank of Example 3. FIG. In the figure, ■ Solder tank 2... Solder spout 6... Solder reservoir 7... Upper end of the spout lO... Molten solder ii... Solder surface 12... Printed circuit board 13-16. ... Splashing wave a la + la 2 t
a: +...Horizontal plane f where the upper end 7 is located...Flow of molten solder

Claims (4)

[Claims] (1) A solder spout is provided at the top of the tank, and a solder reservoir is provided above the nozzle, and molten solder is fed from the solder spout to the solder reservoir to remove the solder in the reservoir. A solder bath characterized by being equipped with a solder feeding mechanism that forms blown-up waves on the surface. (2) The solder nozzle is comprised of a plurality of nozzles whose upper ends are located on the same horizontal plane, and the distance between the upper ends of the nozzles and the solder surface in the solder reservoir is all the same. The solder bath according to claim 1. (3) The solder bath according to claim 1 or 2, wherein the solder nozzle includes several types of nozzles having different diameters. (4) A claim characterized in that the solder nozzle comprises a plurality of nozzles whose upper ends are located on different horizontal planes, and the intervals between the upper ends of the nozzles and the solder surface in the solder reservoir are different from each other. 1. The solder tank described in 1.