JP3114534B2 - Flux supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for supplying a flux used for flow soldering of a printed wiring board in various electronic devices.

[0002]

2. Description of the Related Art In recent years, there is an urgent need to take measures to prevent exposure of volatile solvents in flux used for flow soldering of printed wiring boards. A conventional method and apparatus for supplying flux before flow soldering will be described below.

FIG. 2 shows a foaming fluxer as a conventional flux supply device. In FIG. 2, reference numeral 201 denotes a flux tank, 202 denotes a flux filled in the flux tank 201, 203 denotes an air diffuser disposed at the bottom of the flux tank 201 and has a number of small holes, 204 denotes air bubbles,
05 is a foamed flux, 206 is a conveyor for transporting the printed wiring board 207 above the flux tank 201, 20
8 is a through hole of the printed wiring board 207.

[0004] A flux supply method using the flux supply device configured as described above will be described. By blowing out small bubbles 204 from the diffuser tube 203 immersed in the flux 202 filled in the flux tank 201, the flux 202 is made into a foam 205. When the lower surface of the printed wiring 207 conveyed by the conveyor 206 touches the bubble 205, the flux 202
The flux 202 penetrates into the through hole 208 by breaking the bubble 204.

[0005]

However, in the prior art described above, since the flux 202 contains alcohol such as IPA (isopropyl alcohol), a volatile solvent vapor is generated during the work, and the human body, fire, etc. Danger arises. Further, the flux 202 easily absorbs moisture, and the specific gravity becomes higher due to the inclusion of moisture.
Since the solid content ratio increase (specific gravity increase) due to evaporation becomes indistinguishable, specific gravity control by IPA replenishment becomes impossible. When the liquid state such as the specific gravity and the viscosity of the flux 202 changes, the foaming state is affected.
Need to be replaced regularly, which is inferior in workability and economy.

The present invention has been made to solve the above-mentioned conventional problems and does not generate a volatile solvent during the operation, thereby ensuring safety against human body and fire. It is an object of the present invention to provide a flux supply method and a flux supply device capable of performing stable supply only by replenishment without performing periodic replacement, and thus improving workability and economy. Is what you do.

[0007]

[0008]

According to the present invention, there is provided a flux supply apparatus for achieving the above object, comprising : a vacuum chamber; means for maintaining the inside of the vacuum chamber in a vacuum or reduced pressure atmosphere; A crucible and a heater provided at the lower portion for heating a flux composed of only components that are not volatile at room temperature, and a printed wiring board can be transported in the vacuum chamber above the flux heating crucible. And a cooling unit provided at an upper part of the vacuum chamber and cooling an atmosphere near the printed wiring board carried by the carrying unit.

According to another aspect of the present invention, there is provided a flux supplying apparatus including a printed wiring board stocker on a side of a vacuum chamber.

[0010] As the flux, rosin which exhibits non-volatility at room temperature and its modified products such as abietic acid, dehydroabietic acid, dihydroabietic acid,
Neoabietic acid, pimaric acid, isopimaric acid, leopimaric acid, isodextropimaric acid alone,
Alternatively, it can be composed of a plurality.

[0011]

Therefore, according to the present invention, in a vacuum or reduced-pressure atmosphere, a flux composed only of components that are not volatile at room temperature is heated to its melting point or more, and the generated steam is attached to a printed wiring board. Thus, there is no generation of volatile solvents during the operation, and stable supply can be performed only by replenishment without performing flux liquid management and periodic replacement.

[0012]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway front view showing an outline of a flux supply apparatus according to an embodiment of the present invention. FIG.
As shown in FIG. 1, a stocker chamber 2 is formed on the side of the vacuum chamber 1. The bottom of the vacuum chamber 1 is connected through a valve 3 to a vacuum pump 4 of a rotary type, an oil diffusion type or the like. A flux heating crucible 5 and a flux heating heater 6 are provided at a lower portion in the vacuum chamber 1. The heating crucible 5 is filled with a flux composed of only components that are not volatile at room temperature, in this embodiment, a non-volatile flux 7 composed of abietic acid alone.

In the upper part of the vacuum chamber 1, a conveyor 8 is provided above the crucible 5 for heating the flux.
The transfer conveyor 8 is provided so that a transfer chain 9 is hung endlessly on sprockets 10 and 11 arranged in the stocker chamber 2 and is provided so as to cross the vacuum chamber 1 in a horizontal direction. As a result, the transport chain 9 travels, and the printed circuit board 12 can be transported from one stocker chamber 2 across the vacuum chamber 1 to the other stocker chamber 2. A water cooling coil 13 is provided in the vacuum chamber 1 above the transport conveyor 8, and a flux attachment plate 14 is detachably provided below the water cooling coil 13. The stocker chamber 2 is provided with a stocker 15 for the printed circuit board 12 on the transfer start side and the transfer end side of the transfer conveyor 8. Reference numeral 16 denotes a flux vapor.

Next, a method for supplying a flux according to an embodiment of the present invention will be described together with the operation of the flux supplying apparatus configured as described above.

First, a non-volatile flux 7 consisting of abietic acid alone is supplied to the flux heating crucible 5, the valve 3 is opened and the vacuum pump 4 is operated to reduce the pressure in the vacuum chamber 1 to 0.1 Pa.

Next, the flux heating heater 6 is energized to heat the non-volatile flux 7 made of abietic acid in the crucible 5 to a temperature of 172 ° C. or more, which is the melting point.
Since it is under reduced pressure, the nonvolatile flux 7 starts to evaporate vigorously. Then, the printed circuit board 12 stored in the stocker 15 is sent into the vacuum chamber 1 by the transport conveyor 8, and the vapor 16 of the nonvolatile flux 7 adheres to the printed circuit board 12. At this time, since the water-cooling coil 13 is disposed above the transport conveyor 8, the atmosphere near the transported printed circuit board 12 is cooled, and the flux vapor 16 can be easily condensed on the printed circuit board 12. The printed circuit board 12 to which the flux 7 has been supplied is discharged from the conveyor 8 and then stored in the stocker 15.

Further, since the water-cooling coil 13 is covered with the detachable flux-proof plate 14, the adhesion of the flux 7 is prevented and the collection thereof is facilitated.

If the non-volatile flux 7 is supplied according to the present embodiment, no volatile solvent is generated during the operation, and safety against human bodies and fire can be ensured. During the operation, the flux 7 is a liquid, but since it is in a reduced pressure atmosphere, the adsorption of moisture is extremely small. During the preparation, the flux 7 is stable as a solid or a high-viscosity liquid depending on the composition. Therefore, stable supply can be performed only by replenishment without performing flux composition management and periodic replacement.

[0020]

As described above, according to the present invention, in a vacuum or reduced-pressure atmosphere, a flux composed only of components that are not volatile at room temperature is heated to its melting point or higher, and the generated steam is printed. Since it adheres to the plate, no volatile solvent is generated during the operation, and safety against human body and fire can be achieved. Further, the flux solution control, can be performed only by stable supply to replenish even without periodic replacement can and <br/> this to improve the workability and economy. The pudding conveyed by the conveying means
Cooling means for cooling the atmosphere near the wiring board.
As a result, flux vapor condenses on the printed wiring board
Can be scooped.

[Brief description of the drawings]

FIG. 1 is a partially broken front view showing a flux supply device according to an embodiment of the present invention.

FIG. 2 shows a conventional flux supply device (foaming fluxer)
A partially broken front view showing

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Stocker room 4 Vacuum pump 5 Crucible for flux heating 6 Heater for flux heating 7 Non-volatile flux 8 Conveyor 12 Printed circuit board 13 Water cooling coil 15 Stocker 16 Flux steam

Claims (3)

(57) [Claims] 1. A vacuum chamber, means for maintaining a vacuum or reduced-pressure atmosphere in the vacuum chamber, and heating a flux provided at a lower portion in the vacuum chamber and formed only of components which are not volatile at room temperature. A crucible and a heater for carrying, a conveying means provided so as to be able to convey a printed wiring board in the vacuum chamber above the flux heating crucible, and an upper part of the vacuum chamber, wherein the conveying means And a cooling means for cooling an atmosphere in the vicinity of the printed wiring board to be transported. 2. A supply device of the flux according to claim 1, further comprising a stocker of the printed wiring board on the side of the vacuum chamber. 3. A rosin whose flux exhibits non-volatility at normal temperature and its modified products, abietic acid, dehydroabietic acid, dihydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid, leopimaric acid, and isodextropimaric acid. of, alone or feeder flux configurations claims 1 or 2, wherein a plurality.