JP3235877B2 - Dip soldering equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dip soldering apparatus for soldering electronic components to a printed circuit board.

[0002]

2. Description of the Related Art In recent years, in order to eliminate the step of cleaning a printed wiring board after soldering, a low-residue flux is applied.
2. Description of the Related Art A method of performing soldering using a dip soldering apparatus in which a portion to be soldered is in an atmosphere of an inert gas has been used.

Hereinafter, an example of the above-described conventional dip soldering apparatus will be described with reference to the drawings. FIG.
FIG. 4 is a partial perspective view of a conventional dip soldering apparatus in a partial cross section, and FIG. 4 is a view of FIG. 3 viewed from the direction of arrow a.

In FIGS. 3 and 4, reference numeral 1 denotes a printed wiring board to which an electronic component 2 is temporarily joined. Reference numeral 3 denotes a conveyor, and the printed wiring board 1 is moved by an arrow b
Transport in the direction. Conveyor 3 is 4 ゜ to 6 in the direction b.
゜ About uphill slope. Reference numeral 5 denotes a pre-heater, which performs pre-heating of the printed wiring board 1. Reference numeral 6 denotes a dip tank, which blows out the molten solder filled therein, and the printed wiring board 1 to which the molten solder jet 8 of the first layer 7 and the molten solder jet 10 of the second tank 9 have been conveyed. To solder. A cooling fan 11 cools the printed wiring board 1 after soldering. 1
Reference numerals 2 and 13 denote pipes for supplying an inert gas supplied by an inert gas supply means 19 to a portion to be soldered.
A manual valve 14 is provided in the middle of the pipes 12, 13.
It is possible to adjust the flow rate of the inert gas. Reference numeral 15 denotes a plurality of nozzles, which blows out an inert gas supplied through the pipe 13 toward the conveyed printed circuit board 1.

[0005] As shown in an enlarged perspective view of a partial cross section of FIG. 5, the nozzle 15 is provided with a blowout hole 16, and an inert gas is blown out through the blowout hole 16. Reference numeral 17 denotes a cover, which shields a portion to be soldered from the outside. Reference numeral 18 denotes a curtain, which suppresses the flow of air between the outside and the inside of the cover 17. This curtain 18 is arranged so as to contact the printed wiring board 1 to be conveyed,
The printed wiring board 1 pushes the curtain 18 away and passes.

FIG. 6 shows a dip tank 6 for soldering shown in FIG.
Is shown, and the operation thereof will be described below with reference to FIGS.

First, the printed circuit board 1 passes above the pre-heater 5 and is pre-heated by the conveyor 3 which conveys at a constant speed.

Next, the printed wiring board 1 passes above the dip tank 6 and is soldered by the conveyor 3 in contact with the jets 8 and 10. At this time, the upper and side surfaces are covered with a cover 17, and an inert gas is blown out from the nozzle 15 in the upward, downward, and oblique directions in the direction of arrow c, so that the oxygen concentration around the printed wiring board 1 is kept low.
The distribution of the amount of the inert gas blown from each nozzle 15 is set in advance by operating the manual valve 14.

The printed wiring board 1 is connected to the conveyor 3
As a result, the cooling fan 11 passes above and is cooled by the cooling fan 11.

[0010]

However, in the above arrangement, the distribution of the amount of the inert gas blown out from each nozzle is preset by operating a manual valve, so that the printed wiring board to be soldered is used. It was not possible to change the blowout amount from each nozzle in accordance with the progress of the transfer of. For this reason, the portion where the printed wiring board comes into contact with the molten solder cannot be efficiently made to have an inert gas atmosphere, and a problem has arisen that a large amount of inert gas needs to be supplied.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a dip soldering apparatus in which a portion in which a printed wiring board comes into contact with molten solder is efficiently made to have an inert gas atmosphere.

[0012]

In order to solve the above-mentioned problems, a dip soldering apparatus according to the present invention provides a dip soldering apparatus in which the amount of inert gas blown varies according to the progress of the conveyance of a printed wiring board to be soldered. Control means for supplying inert gas.

[0013]

According to the present invention, by providing control means for changing the blowing amount of the inert gas supplied from the inert gas supply means to the plurality of nozzles in accordance with the progress of the conveyance of the printed wiring board, the printing is provided. The portion where the wiring board comes into contact with the molten solder can be efficiently made to have an inert gas atmosphere.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dip soldering apparatus according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an essential part showing a part of a dip soldering apparatus according to an embodiment of the present invention in a cross section.

In FIG. 1, the same components as those of the prior art shown in FIG. 3 and the like are denoted by the same reference numerals and the description thereof will be omitted, but the configuration different from that of FIG. 3 and the like will be described below.

In FIG. 1, reference numeral 14e denotes an electromagnetic valve disposed in the middle of the pipes 12 and 13. The control means 20 enables the flow rate of the inert gas supplied from the inert gas supply means 19 to be adjusted. . Reference numeral 21 denotes a sensor for detecting the presence or absence of the printed wiring board 1, and the detection result is sent to the control means 20. 15a ~
Reference numeral 15g denotes a nozzle which blows out an inert gas supplied through the pipe 13 toward the printed wiring board 1 being conveyed. The structure of the nozzles 15a to 15g is the same as the conventional one shown in FIG.

FIG. 2 is a front view mainly showing the dip tank for soldering shown in FIG. 1, and the operation thereof will be described below with reference to FIGS.

First, the printed wiring board 1 is preheated by the conveyer 3 which conveys at a constant speed, passing above the preheater 5. Next, the printed wiring board 1 is conveyed into the cover 17 by the conveyor 3, passes over the dip tank 6 in a state of being in contact with the jet 8 and the jet 10, and is soldered.

At this time, until the printed circuit board 1 is detected by the sensor 21, the inert gas supplied by the inert gas supply means 19 is supplied to each nozzle so that the inside of the cover 17 becomes a uniform inert gas atmosphere. The air is blown out in the direction of the arrow c distributed to 15a to 15g.

While the printed wiring board 1 is detected by the sensor 21, the control means 20 increases the blowing amount from the nozzle 15g, and decreases the blowing amount from the other nozzles 15a to 15f. Above the second layer 9, the concentration of the inert gas in the portion where the printed wiring board 1 comes into contact with the molten solder is increased.

When the printed wiring board 1 moves and is no longer detected by the sensor 21, the control means 20 blows out the inert gas from the nozzles 15a to 15g in the original distribution. Finally, the printed wiring board 1 is a conveyor 3
As a result, the cooling fan 11 passes above and is cooled by the cooling fan 11.

As described above, according to the present embodiment, by providing the inert gas supply control means in which the blowing amount of the inert gas changes according to the progress of the conveyance of the printed wiring to be soldered, Normally, the inert gas supplied by the inert gas supply means is distributed and blown out to the respective nozzles so that the inside of the cover becomes a uniform inert gas atmosphere. Since the inert gas can be blown intensively to the portion to be welded, the portion where the printed wiring board comes into contact with the molten solder can be efficiently made to have an inert gas atmosphere.

[0023]

As described above, the dip soldering apparatus according to the present invention comprises a means for controlling the supply of inert gas in which the blowing amount of the inert gas changes according to the position of the printed wiring board to be soldered. With this arrangement, a portion where the printed wiring board comes into contact with the molten solder can be efficiently made to have an inert gas atmosphere.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of a part of a dip soldering apparatus according to an embodiment of the present invention in a cross section.

FIG. 2 is a front view mainly showing a dip tank for performing soldering shown in FIG. 1;

FIG. 3 is an essential part perspective view showing a cross section of a part of a conventional dip soldering apparatus.

FIG. 4 is a view seen from the direction of arrow a in FIG. 3;

FIG. 5 is an enlarged perspective view of a partial cross section of the nozzle of FIG. 3;

FIG. 6 is a front view mainly showing a dip tank for performing soldering shown in FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printed wiring board, 2 ... Electronic components, 3 ... Conveyor, 5 ... Preheater, 6 ... Dip tank, 7 ... First
Tank, 9: Second tank, 8, 10: Jet, 11: Cooling fan, 12, 13, Pipe, 14e: Electromagnetic valve, 15a-
15g nozzle, 17 cover, 19 inert gas supply means, 20 control means, 21 sensor.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-174778 (JP, A) JP-A-57-62592 (JP, A) JP-A-3-86371 (JP, A) JP-A-3-3 77774 (JP, A) JP-A-3-216274 (JP, A) JP-A-3-70853 (JP, U) JP-A-61-17276 (JP, U) JP-A-3-76680 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05K 3/34 B23K 1/08

Claims (1)

(57) [Claims] 1. A means for detecting the presence or absence of a printed wiring board conveyed to a dip tank by a conveyor, and a means for detecting the presence of the printed wiring board from the detecting means until the presence of the printed wiring board is detected. The active gas is distributed to a plurality of nozzles so that the inside of the cover becomes a uniform inert gas atmosphere.Then, while the printed circuit board is being detected, the amount of the inert gas blown out from the nozzle at the final position is increased. Means for controlling an electromagnetic nozzle that reduces the amount of inert gas blown out of nozzles other than the final position.