JPH05208265A - Flux applying device - Google Patents

Abstract

PURPOSE:To prevent the excess application of flux and to improve a soldering treatment by providing a capillary force generating member downward on the side opposite from a soldering surface. CONSTITUTION:The flux jetting from a jetting part 3 is applied in contact with the soldering surface 1A of a circuit board 1 passing above the flux in proximity thereto. More than the needed flux tends to be attracted toward the soldering surface 1A on which the flux moves and passes by the surface tension of the soldering surface 1A, the surface tension of the flux and the interfacial tension of both. The capillary force is imparted downward to the flux by the capillarity of the capillary force generating member 4 juxtaposed on the side of the jetting part 3 in the direction where the circuit board 1 is transported. As a result, the flux is disconnected downward from the soldering surface 1A by its own weight coupled with the capillary force. The flux is thus prevented from being attracted toward the soldering surface 1A and being excessively applied in the form of unequalness on the soldering surface 1A.

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. Includes pine or cotton to improve adhesion with solder.

[0006] It is for giving the following effects.

[0007] Conventionally, this flux coating apparatus is arranged in parallel under the circuit board, which is transported with the soldering surface facing down toward the solder bath, in the solder bath on the front side in the transport direction via a substrate preheating device. In this state, a jet portion for jetting the flux (overflow) is provided at a position where the soldered surface of the circuit board to be conveyed closely passes above.

Specifically, for example, a hood which projects above the level of the flux liquid surface is provided in a flux tank containing the flux, and a jet port having a width corresponding to the soldered surface width is provided at the upper end of the hood as a jet portion. A foam tube is installed inside this hood.

Therefore, the flux is foamed by the foam tube and jetted from the jet port, and is applied in contact with the soldered surface of the circuit board being conveyed as shown in FIG.

[0010]

As described above, in the conventional flux coating apparatus, as shown in FIG. 4, the flux 2 jetted from the jet portion 3 is transferred to the soldered surface 1A of the circuit board 1 passing through. When applying, the flux 2 is attracted to the soldering surface 1A due to the surface tension of the soldered surface 1A, the surface tension of the flux 2 and the interfacial tension between the two, and more flux 2 than necessary adheres and is excessively applied. ..

In particular, this flux 2 has a viscosity because it contains a component such as pine nut and the like, and since it is generally foamed as described above, it is not necessary to simply overcoat it, and as shown in FIG. In addition, the coating amount is not uniform and the coating amount becomes uneven.

As described above, in the conventional structure, the flux 2 is excessively applied or the applied amount is uneven, which causes the following problems.

In the subsequent soldering process, the activation of the soldered portion due to the flux (removal of oxide film and improvement of solder adhesion) becomes non-uniform, resulting in poor solder fluidity and poor soldering.

The flowability of the solder becomes non-uniform, and a pinhole phenomenon where solder does not attach occurs in a portion having a high fluidity, and a bridge phenomenon in which solder is attached to unnecessary portions in a portion where the fluidity is too low. It may occur.

Since the degree of adhesion of the solder is not determined, the conditions of the automatic soldering device for performing the soldering process are not determined,
Design becomes complicated.

After applying the flux, there is a problem that the flux drips into the inside of the soldering device during transportation to the next step of the circuit board, and the inside of the device becomes dirty.

The present invention solves such a problem, and provides a flux coating device having an excessive coating preventing function capable of coating the soldered surface with flux more than necessary and evenly coating the flux. It is a problem.

[0018]

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

A flux applying apparatus in an automatic soldering process of a circuit board for applying flux 2 to a soldering surface 1A of the circuit board 1 as a pretreatment for soldering the circuit board 1 to the circuit board 1 to be transported. Soldering surface 1
A jet portion 3 for jetting the flux 2 upward is provided at a position where A passes closely above, and the flux 2 jetted from the jet portion 3 on the side of the jet portion 3 in the carrying direction of the circuit board 1 is soldered upward. A capillary force generating member 4 that pulls in by a capillarity action is provided in a downward direction on the opposite side to the surface 1A, and the cleaning agent 2 applied to the soldered surface 1A by the conveyance of the circuit board 1 is unnecessary more than necessary. The present invention relates to a flux coating apparatus, which is configured to prevent the soldered surface 1A from being attracted and excessively coated.

[0020]

The flux 2 jetted from the jet portion 3 comes into contact with and is applied to the soldered surface 1A of the circuit board 1 which passes above the jet portion 3 closely.

At this time, the surface tension of the soldered surface 1A, the surface tension of the flux 2 and the interfacial tension between the two tend to attract more flux 2 than necessary to the moving soldered surface 1A. The capillary force (pull-in force) is given downward by the capillary action of the capillary force generating member 4 arranged in parallel on the side of the circuit board 1 in the conveyance direction. Therefore, for example, as shown in FIG. In addition to its own gravity, this capillary force separates the flux 2 downward from the soldered surface 1A, pulls it toward the soldered surface 1A, and the flux 2 becomes uneven on the soldered surface 1A as shown in FIG. 4 showing a conventional example. Therefore, excessive application is prevented.

[0022]

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

In the flux tank containing the flux 2, a hood body 5 projecting upward above the level of the flux liquid surface,
A foam tube 6 which is arranged in the width direction of the circuit board 1 which conveys and passes above and which causes the flux 2 to foam and jet into the hood body 5.
And a jet long hole is formed as a jet portion 3 at a position close to the soldered surface 1A on the lower surface side of the circuit board 1 through which the hood body 5 is conveyed in the width direction of the upper end of the hood body 5.

In this embodiment, the capillary force generating members 4 are arranged in parallel so as to be close to the jetting portion 3 on the side of the conveying direction.

An embodiment of the capillary force generating member 4 which is the main part of the present invention will be described.

In this embodiment, the circuit board 1 is provided at both ends of the jet portion 3.
The mounting portions 7 and 7 are provided in a protruding manner toward the conveyance direction side of, and the mounting shaft 8 is laid between the mounting portions 7 and 7 in parallel with the jet portion 3, and the mounting shaft 8 is several mm long. A large number of gap forming plates 9 are provided with a certain gap 10 therebetween.

Therefore, the gaps 10 are evenly arranged in a juxtaposed state in the jet part 3, and since the gaps 10 penetrate downward from above, the flux 2 jetting upwards is directed downwards. The capillary force that pulls into the gap 10 is always generated uniformly in the width direction.

The width of the gap 10 is designed so that an appropriate capillary force is generated, and the flux 2 does not stay in the gap 10 so that the capillary force is always maintained.

The method of forming the gap 10 in the capillary force generating member 4 and the shape thereof are not limited to those in the present embodiment, but may be directed downward (opposite diagonally downward) with respect to the upper soldered surface 10. It is sufficient if a capillary force is generated), and the gap 10 may be provided in parallel with the jet part 3 in one line,
A plurality of gaps 10 may be arranged side by side in the jet section 3, and the gap forming plate 9 is further rotated in the same manner as in the present embodiment to generate a pulling force by this rotation in addition to the capillary force. Alternatively, the pulling force may be increased.

Further, the structure of the flux applying apparatus to which the present invention is applied can be designed as appropriate, and may be applied to, for example, a flux applying apparatus of the type which does not foam the flux.

In the figure, reference numeral 11 is a conveying claw for supporting and conveying the circuit board 1, and 12 is projectingly provided at both ends of the jet portion 3, so that the flux 2 wraps around to the side edge portion of the circuit board 1 and the jet flow is prevented. A guide protruding edge portion 13 for guiding the upper end of the guide protruding edge portion 12 is inclined upward in the conveying direction, and the height of the top edge is designed so that the height of the circuit board 1 is appropriate. It is a claw guide edge.

[0032]

Since the present invention is constructed as described above, the flux is always drawn downward by the capillary force generated by the capillary action of the capillary force generating member, and the flux is attracted to the soldered surface more than necessary. Provided is an excellent flux coating device in an automatic soldering process of a circuit board, which can be applied uniformly without being over-coated, has a good soldering process in the next step, and can perform an appropriate soldering process. be able to.

Further, since the pulling force is generated by the action of capillarity, a very excellent flux applying device which does not require a drive source and can always generate a constant pulling force is provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration perspective view of a present embodiment.

FIG. 2 is a side view in a use state before carrying a circuit board according to the present embodiment.

FIG. 3 is a side view of the present embodiment in a use state when passing through a circuit board.

FIG. 4 is a side view of a conventional example in a use state when passing through a circuit board.

[Explanation of symbols]

 1 circuit board 1A soldering surface 2 flux 3 jet part 4 capillary force generating member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Arakawa 2-32 Higashi Zao, Nagaoka City, Niigata Prefecture Nippon Seiki Co., Ltd.

Claims (1)

[Claims] 1. A flux applicator in an automatic soldering process of a circuit board for applying flux to a soldering surface of the circuit board as a pretreatment for soldering the circuit board. A jet portion for jetting the flux upward is provided at a position where the surface closely passes above, and the flux jetted from the jet portion on the side of the jet direction of the circuit board on the side opposite to the soldered surface on the upper side. A capillary force generating member that pulls in due to a capillary action is installed side by side, and the flux that is applied to the soldered surface by the conveyance of the circuit board is attracted to the soldered surface more than necessary and is applied excessively. A flux applicator characterized in that it is configured to prevent