JP3131232B2 - Automatic 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 an automatic soldering apparatus for soldering a printed circuit board.

[0002]

2. Description of the Related Art When a printed circuit board is brought into contact with a jet solder to perform soldering, soldering defects such as icicles and bridges may occur. The cause of these defects is that the surface of the molten solder attached to the printed circuit board is oxidized, and the solid oxide covers the surface of the molten solder and lowers the surface tension of the molten solder.

Therefore, when the surface of the molten solder between the adjacent soldering portions is oxidized when the printed circuit board separates from the molten solder, the molten solder cannot be drawn into the respective soldering portions due to surface tension, and the molten solder cannot be drawn. The solder solidifies to form a bridge, and the molten solder attached to the tip of the lead cannot be drawn into the lead, resulting in an icy tip having an acute angle.

It is known that when the printed circuit board exits the jet solder bath, it is possible to prevent the generation of icicles and bridges by reducing the oxidation of the molten solder attached to the printed circuit board. H, CO,
An automatic soldering apparatus has been proposed in which an inert gas such as He or Ar is blown to lower the oxygen concentration around the PBP (see Japanese Patent Publication No. 54-3215, Japanese Patent Publication No. Sho 62-267066, and Japanese Patent Application Laid-Open No. 62-267066). 64-34577).

[0005]

However, even if soldering of a printed circuit board is performed by a conventional automatic soldering apparatus which blows an inert gas onto a PBP (hereinafter referred to as "gas flow soldering apparatus"), there are no icicles or bridges. I couldn't do that. The reason is that the oxygen concentration of the PBP cannot be sufficiently reduced in the conventional gas flow soldering apparatus to such an extent that the molten solder adhering to the printed circuit board does not cause icing or bridging.

[0006] In order to reduce the oxygen concentration of PBP in a gas flow soldering apparatus, the tip of a nozzle (hereinafter referred to as a gas nozzle) for blowing an inert gas is made as small as possible with PBP.
It is only necessary to prevent air from getting caught in the PBP by approaching the PBP. However, since the lead protrudes long from the lower surface of the printed circuit board, the gas nozzle is located only at a position where it does not hit this lead in the conventional gas flow solder bath. Could not be installed. When the gas nozzle hits the lead immediately after soldering, the lead may bend, or the solidified solder adhered to the lead may be cracked, resulting in poor contact. In order to prevent such inconvenience, in the conventional gas flow soldering bath, a gas nozzle is installed at a remote position in front of the PBP to spray an inert gas, and the oxygen concentration cannot be sufficiently reduced. Was. An object of the present invention is to provide an automatic soldering apparatus capable of lowering the oxygen concentration near PBP without bringing the gas nozzle close to PBP.

[0007]

Means for Solving the Problems The present inventors have observed visible smoke in a gas flowing state in a conventional gas flow soldering apparatus. Since the nozzle to be discharged was provided in front of the printed circuit board in the traveling direction, it was found that the smoke blown out from the nozzle hit the PBP and then escaped from the side of the PBP into a turbulent state. That is, if turbulence occurs when escaping from a gas close to PBP, it is considered that air enters from between the turbulence. Therefore, the present inventors have proposed that PBP
The present invention has been completed by noting that it is difficult for air to enter the PBP if gas is not allowed to escape from the vicinity.

According to the present invention, flux application, preheating, molten solder immersion,
In an automatic soldering apparatus that performs soldering by performing processing such as cooling, nozzles for blowing out inert gas are installed on both sides of the peelback point where the printed circuit board separates from the molten solder, and the inert gas is peeled back from the nozzle. This is an automatic soldering device characterized by blowing out in a direction along a point.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view of a main part of an automatic soldering apparatus according to the present invention, and FIG. 2 is a side sectional view of the same. The automatic soldering apparatus is provided with a pair of conveyors 1, 1 one of which is fixed and the other is movable (arrow X). Many nails 2 on the conveyor
Are installed so as to travel in the arrow Y direction.

The conveyor is inclined upward by 4 to 6 degrees in the traveling direction (arrow Y), which makes it easy to separate the printed board and the molten solder when the printed board is soldered in a jet solder bath described later. That's why. Below the pair of conveyors, processing devices such as a fluxer (not shown), a blow heater (not shown), a jet solder bath 3, and a cooling device (not shown) are provided. Nozzle 4 in jet solder bath 3
Is installed, and the nozzle is a pair of nozzle plates 5, 5 '.
And a pair of side plates 6 and 6, and the molten solder S is jetted upward by a pump (not shown). One nozzle plate 5 is provided with a downwardly-entering former 7, and the other nozzle plate 5 ′ is provided with a flat exit-side former 7 ′. Below the pair of conveyors, an inert gas blowing nozzle 8 having a number of holes formed in a pipe is mounted substantially horizontally via a mounting plate 9. The mounting position of the blow-out nozzle is in front of the PBP in the traveling direction (arrow Y), and is a position where the inert gas can be blown into the corner formed by the printed circuit board and the exit-side former 7 '.

Next, the soldering state of the printed circuit board in the automatic soldering apparatus of the present invention will be described. The printed board P conveyed by the nails of the conveyor is applied with flux by a fluxer, preheated by a buri heater, and then comes into contact with the molten solder S jetted from the jet solder bath 3 to perform soldering. Inert gas is blown into the PBP portion from the nozzles 8 on both sides thereof, and the printed circuit board separates from the molten solder in an inert atmosphere. At this time, since the inert gas flows from both sides of the PBP, turbulence does not occur here and air does not enter the PBP. In the embodiment, a carrierless type automatic soldering apparatus that transports a printed circuit board with a nail has been described.
It goes without saying that the present invention can also be applied to a carrier type automatic soldering apparatus that transports a printed circuit board by a carrier.

[0012]

According to the automatic soldering apparatus of the present invention, nozzles for blowing out an inert gas are installed on both sides of the PBP where the printed circuit board is separated from the molten solder, and the inert gas is blown out from the nozzles in a direction along the PBP. By doing so, the inert gas does not flow out of the vicinity of the PBP as a turbulent flow. Therefore, the automatic soldering device of the present invention
Since air does not flow from both sides around the PBP, the oxygen concentration can be kept low, and there is an unprecedented superior effect that reliable soldering can be performed by eliminating soldering defects such as icicles and bridges.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a main part of an automatic soldering apparatus according to the present invention.

FIG. 2 is a side sectional view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conveyor 2 Claw 3 Jet solder tank 4 Nozzle 8 Inert gas blowing nozzle 9 Mounting plate P Printed circuit board S Melted solder

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuo Fujita 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Hisashi Suwa 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo No. Within Sony Corporation (72) Inventor Zen Mitsuo 23 Senju Hashido-cho, Adachi-ku, Tokyo Inside Senju Kinzoku Kogyo Co., Ltd. In-company (56) References JP-A-59-218262 (JP, A) JP-B-54-3215 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 1/08- 1/08 320 H05K 3/34 506

Claims (2)

(57) [Claims] 1. An automatic soldering apparatus for performing soldering by carrying out processes such as flux application, preheating, immersion of molten solder, and cooling while transporting a printed board on a conveyor, wherein the printed board is peeled away from the molten solder. A nozzle for blowing out an inert gas is installed on both sides of the point , and the inert gas is discharged from the nozzle to the peel back port.
An automatic soldering apparatus characterized by blowing out in the direction along the point . 2. A nozzle according to claim 1, wherein said inert gas blowing nozzle is provided on a frame of a conveyor.
Automatic soldering apparatus according to.