JPH0592263A - Spray type flux applying device - Google Patents

Abstract

PURPOSE:To provide the spray type flux applying device which applies flux thinly and uniformly on a soldering part, prevents the generation of fine solder balls at the time of soldering, prevents a short circuit between electrodes and can prevent the generation of a non-solder place at the time of soldering a printed circuit board formed by packaging electronic parts. CONSTITUTION:A motor-driven brush 9 is thrown into flux liquid 4 of a flux vessel 1 to the extent that its nap is immersed therein, this brush 9 is rotated, air injected from an air spray nozzle 8 located in the vicinity thereof is applied thereto to make the flux misty which is applied on the printed circuit board, by which the generation of the solder balls, the short circuit between the electrodes and the generation of the solder open place can be prevented and the soldering quality is remarkably improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention cleans the copper foil surface of a printed circuit board and the surface of electrodes or lead wires of electronic parts to mount the parts on a printed circuit board and solder them together to prevent solder wettability. The present invention relates to a flux coating device for coating for the purpose of increasing the flux.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 3 and 4, a flux applying means for a printed circuit board has a porous tube 3 installed in a flux tank 1, and both ends of the porous tube 3 are sealed. Then, by sending air into the air, the air passes through the holes of the perforated pipe 3 and leaks to the outside, thereby foaming the flux.

If the air pressure is continuously supplied in a stable and uniform state, the foamed particle size of the flux can be maintained in a stable and uniform state.

If the printed circuit board 5 on which electronic components are mounted is passed through the flux foaming state, flux can be applied to the soldered surface. In the flux application by the above-described flux foaming device, the foam particles are destroyed by the contact of the foam particles with the printed circuit board 5 which is the object to be soldered, and the flux application is completed at the same time.

[0005]

(1) However, in the flux coating according to the above method, the diameter of the foamed particles changes depending on the change of the air pressure as the foaming source and the kind of the holes of the foaming porous tube 3, and the surface of the printed circuit board 5 is changed. There is unevenness in the thickness of the flux applied to the. When the printed circuit board having the uneven flux coating is passed through the jet type solder bath, the flux is heated to the soldering temperature. As a result, a solder repelling phenomenon occurs in the thickly applied portion of the flux, and the jet solder is made into fine particles. Then, the fine particle solder adheres to the printed circuit board 5. Printed circuit board 5
The finer the pattern of the electrodes, the more short-circuiting between the electrodes occurs, which causes a defect. The greater the uneven flux application, the greater the phenomenon.

The first object of the present invention is to solve this problem. (2) In the flux application by the foaming method, the foamed particles of the flux are formed and the flux is applied to the printed circuit board 5, and the foamed state cannot be secured unless the particle diameter is a certain value or more due to the relationship between the foam tube and the air thickness. If the soldering surface becomes complicated or the density of mounting the components becomes higher, the flux may be incompletely applied to the narrow gaps or the fine parts of the chip component, resulting in defective soldering. The second object of the present invention is to solve this problem.

(3) Thirdly, since the solvent that dilutes the flux to a constant concentration is vaporized by foaming, a large amount of diluent is required to keep the flux concentration constant, and it is necessary to manage it. It becomes severe. It is intended to improve such an economic aspect.

[0008]

In order to solve the above-mentioned problems, the present invention uses a spray type flux applying means. The structure of the spray type flux device is to immerse the tip of the brush in the flux tank, rotate it at a constant speed, and at the same time eject air from the slit type air nozzle, which is then applied to the tip of the tip of the brush to which flux has adhered. Spraying and making the flux mist, spraying on the back surface (soldered surface) of the printed circuit board and applying flux.

[0009]

When the flux is applied by the above method, (1) the flux is misted and applied to the soldered surface of the printed circuit board.

Since the flux coating thickness can be thinly and uniformly controlled, the crater phenomenon at the time of soldering is suppressed, the generation of solder particles is prevented, and the quality is stabilized.

Since the flux to be applied is in a mist state, it can be applied to a narrow portion. As a result, flux can be applied even in the gap between the chip component and the printed circuit board electrode, blowholes can be prevented from occurring during soldering, and the quality of soldering is improved and electrical stability is provided. (2) By immersing the brush in the flux tank and rotating the brush, the volatilization amount of the solvent that controls the specific gravity of the flux is extremely low compared to the foaming method, the management cost is low, and the management weight is easy. .

Since the air does not pass through the flux and excessive absorption of water in the flux is suppressed and the life of the flux is extended, the running cost is reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, the rotating brush 9 is installed in the flux tank 1 by the brush holder 11, the rotating gear 12 is attached to the rotating brush 9, and the motor 13 can be driven and rotated.

The rotation speed can be controlled by controlling the motor rotation speed. For air blowing, the slit nozzle 8 is connected to the air tube 6 at a large number of openings 10 and is installed at a position where the tips (tips) of the printed circuit board 5 and the rotating brush 9 form a straight line.

The tip of the rotary brush 9 is put into the flux tank 1 having the above structure until the tip of the rotary brush 9 is immersed in the flux liquid 4, and the motor 13 is driven to rotate the rotary brush 9. Since the flux adheres to the tips of the rotating brush 9 and rotates, the air is ejected from a slit type air nozzle 8 installed at a position where the tips and the printed circuit board 5 are located on a straight line, that is, a tangential direction of the rotating brush 9 at a predetermined angle. Apply it to the tip of the rotating brush 9. As a result, the flux is applied to the printed circuit board in a mist state. Since there are various sizes of printed circuit boards, the application of mist-like flux is started when the printed circuit board is conveyed on the line connecting the air nozzle and the tip of the brush, and after passing the conveyance, flux application is stopped. A sensor is installed in the circuit board transport unit (not shown) so that flux can be applied only when passing through the printed circuit board.

[0017]

As described above, according to the jet type flux coating apparatus of the present invention, in order to make it possible to coat the flux uniformly and to coat it in a narrow gap, it is possible to prevent the generation of solder particles in jet type soldering. Since the soldering can be suppressed and the soldering to the narrow gap is possible, the soldering strength can be improved more than ever, and the quality can be improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of an apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the front of FIG.

FIG. 3 is a sectional view of a conventional air foaming type flux coating device in a lateral direction (1).

FIG. 4 is a sectional view of the front direction of FIG.

[Explanation of symbols]

 1 Flux Tank 4 Flux Liquid 5 Printed Circuit Board 6 Air Tube 7 Flux Tank Lid 8 Slit Type Air Nozzle 9 Rotating Brush 10 Air Tube 11 Rotating Brush Holder 12 Brush Rotating Gear 13 Brush Rotating Motor

Claims (1)

[Claims] 1. A flux tank, a rotary brush, a part of which is immersed in the flux liquid, an air nozzle for blowing air in a direction of a predetermined tangent to the rotary brush, and a rotary drive means for the rotary brush. A spray type flux applicator.