JPH0134713B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a solder bath for soldering parts such as resistors and transistors mounted on a printed circuit board to a printed circuit board. This invention relates to a new solder tank with a completely different mechanism from the type solder tank.

(Prior Art) As a solder tank for soldering mounted electronic components to a printed circuit board, a jet type solder tank having an elongated solder outlet has been known and often used. Conventional jet-flow solder baths generally include a chamber having a molten solder inlet and an elongated hole outlet in a molten solder bath in an outer tank, with the outlet located above the surface of the molten solder bath. By the rotating action of the rotary blades provided in the chamber, the molten solder taken in from the suction port on the bottom of the chamber is forcefully jetted out from the outlet through the inside of the chamber and transported to the upper part of the solder tank. The structure was such that the solder was sprayed onto printed circuit boards to be soldered, and the excess spouted solder was collected back into the outer tank.

(Problem to be solved by the invention) However, since the jet type solder bath is a method in which molten solder is sprayed onto the printed circuit board, the solder itself has a considerable amount of pressure, so the type of electronic components and the thickness of the printed circuit board are affected. In some cases, there was a tendency for the soldering to become defective. For example, in the case of parts with long leads (leads) or extremely thin boards, poor soldering is likely to occur.

For this reason, it has been desired to develop a solder tank that can perform soldering while the molten solder remains stationary.

Here, we modified the conventional jet-flow solder tank and expanded the outlet to a size that could accommodate the entire printed circuit board, so that the molten solder stored in the solder tank and the printed circuit board could come into surface contact almost simultaneously. There are ways to do this.

However, since soldering is carried out with the molten solder stationary in this solder tank, when the rotating action of the rotor blades is stopped, the molten solder in the chamber is lower than the height of the outlet due to the pressure difference between the chamber and the atmospheric pressure. A problem arose in that it fell down and soldering could not be performed. Furthermore, when the surface of the molten solder in the chamber descends, a difference in surface tension occurs between the center of the surface and the peripheral region near the chamber side wall near the outlet, which causes wrinkles on the surface of the molten solder. There was also the problem that the soldering could not be done properly when the soldering occurred and the next time the jet was used.

SUMMARY OF THE INVENTION An object of the present invention is to provide a solder tank which solves the above-mentioned problems, prevents the surface of the solder from deteriorating when the molten solder is stationary, and allows good soldering when the molten solder is stationary.

(Means for Solving the Problems) The solder tank of the present invention has a suction portion having a suction port for molten solder and equipped with a rotary blade, a blowout portion forming a wide-area blowout port, and a suction portion that has a suction port for molten solder. A chamber consisting of a communication section that communicates with the outlet is installed in the outer tank, and the communication section of the chamber is provided with a blocking wall from the bottom of the chamber to approximately the height of the outlet, and a cover plate. The suction part is extended over the blocking wall to a position below the outlet to form a passage for the molten solder from inside the suction part to the outlet through the position and to the inside of the outlet. The present invention is characterized in that an introduction hole is provided in a portion of the passageway above the outlet.

(Function) In the solder bath of the present invention, a closed passage communicating between a blowout section with a blowout port for molten solder and a suction section located lower than the blowout section is provided at a portion higher than the blowout port by a blocking wall and a cover plate. It is configured through the following, and therefore the following effects are exerted. First, the rotation of the rotor blade takes in the molten solder in the outer tank through the suction port of the suction section, passes through the communication section, and sufficiently supplies it to the blowout section. or close to it. Thereafter, when the rotation of the rotor is stopped and the supply of molten solder is stopped, the molten solder in the communication passageway flows to the suction section and the blowout section at the same time as air flows in from the air introduction hole. Then, on the suction side, the liquid level of the molten solder drops to the same height as the molten solder bath in the outer tank, but on the blowout side, a blocking wall is provided at almost the same height as the blowout port. Therefore, backflow of the molten solder to the suction portion is suppressed, and the liquid level of the molten solder is maintained at substantially the same level. Therefore, the molten solder is formed in a stationary state without a drop in the liquid level, and can be used for soldering in which surface contact is made almost simultaneously with the printed circuit board.

Note that when the molten solder is fed to the blowing part side, a small portion of the solder flows out from the air introduction hole, but there is no problem in practical use. No air entrainment occurs at all.

In addition, the solder tank of the present invention continuously supplies molten solder from the suction part to the blowout part by continuous rotation of the rotor blade, and creates a condition in which the solder constantly overflows from the blowout port. Soldering similar to the case using a tank can also be performed.

(Example) Hereinafter, an example of a solder bath according to the present invention will be described with reference to the drawings.

In Figures 1 to 3 showing the solder bath,
1 is an outer tank for storing molten solder, 2 is a chamber for blowing up molten solder, 3 is a number of heater sleeves arranged at the bottom of outer tank 1, and 4 is arranged in outer tank 1. This is a pipe for thermocut pull.

The chamber 2 has two mounting parts 5 inside the outer tank 1.
It is supported on one side only. This chamber 2 has a molten solder suction port 6 formed at the bottom of the chamber located below the surface of a molten solder bath (not shown) in the outer tank 1, and a molten solder outlet 7. Below the track along which the printed circuit board to be soldered advances, it is formed as a wide-area opening located above the surface of the molten solder bath and into which the printed circuit board can enter.

A rotating shaft 9 having a rotary blade 8 at the lower end is provided directly above the suction port 6 of the chamber 2,
When this rotary shaft 9 rotates under the driving force of a drive device (not shown), the rotor blades 8 are rotated, and the molten solder is taken in from the suction port 6 by the rotational action of the rotor blades 8, and the suction portion The air is fed to the blow-off section through the communication section and blown up from the blow-off port 7. In Figures 1 to 3,
Reference numeral 10 denotes a bearing for the rotating shaft 9 attached to the chamber 2.

Furthermore, as shown in FIGS. 4 and 5, the chamber 2 has a blocking wall 1 at a communicating portion connecting a portion of the inlet 6 and a portion of the outlet 7.
3 is provided to approximately the height of the outlet 7 from the bottom surface of the chamber, and a cover plate 14 extends over the blocking wall 13 in a curved manner from the suction portion to a position below the outlet 7,
A closed passage 11 for molten solder is formed from inside the suction section to the inside of the blowout section through a position above the blowout port 7. The blocking wall 13 is for preventing the molten solder from flowing back from the outlet 7 side to the suction port 6 side, and the lower end edge of the cover plate 14 is located below the outlet 7 because the passage 11 This is to prevent air from getting caught up in the molten solder flowing inside.

Note that the edge of the cover plate 14 may be provided in such a manner that it extends further downward from the state shown in the illustrated example, and further projects upward from the lower side of the air outlet 7.
Reference numeral 15 denotes a small air introduction hole provided in the side wall of the communication portion 12. This air introduction hole 15 is connected to the communication portion 1
It may be provided on the top of the cover plate 14 constituting the cover plate 2.
Further, 16 is a through hole for inserting and removing the rotor blade 8.

Next, the operation of the solder bath described above will be explained.

When it is desired to move and solder the printed circuit board onto the surface of the molten solder that is stationary in this solder tank, the molten solder is fed from the suction part to the blowout part via the communication part by the rotation of the rotor blades. The air is filled up to the height of the outlet 7, and then the rotation of the rotor is stopped.

Then, air flows in through the air introduction hole 15, creating an air pocket at the top of the passage 11, and the molten solder on the side of the outlet 7 is blocked by the blocking wall 13, leading to a suction port with a lower height from the side of the outlet 7. Backflow to the 6th side is prevented. Therefore, since the upper end of the blocking wall 13 is at almost the same height as the outlet 7, the molten solder surface on the side of the outlet 7 is not processed from the outlet 7, so it is not possible to solder the printed circuit board even in a stationary state. Can be done.

In other words, the legs of components such as resistors and transistors are made to protrude from the back side of the printed circuit board, and the printed circuit board on which these components are mounted is moved in the direction of arrow A in Figures 1 and 2 with the back side facing down. When the solder is brought into contact with the surface of the molten solder which is in a stationary state, the back surface of the printed circuit board is soldered.

In some cases, the rotor blade 8 may be rotated continuously,
It is also possible to create a state in which molten solder is constantly blown up from the outlet 7 and perform soldering in that state. In this case, the molten solder is blown up from the outlet 7 to a predetermined height and overflows into the outer tank 1, and the molten solder flows from the outer tank 1 into the chamber 2 and from the chamber 2 into the outer tank 1. It circulates and flows.

(Effects of the Invention) As explained above, according to the present invention, even if the rotational action of the rotor blades provided in the chamber is stopped, the molten solder surface on the outlet side of the chamber does not descend from the water level of the outlet. Since there is no molten solder, it is possible to solder the printed circuit board even when the molten solder is stationary.

Furthermore, by using the solder tank of the present invention, it is possible to successfully solder a printed circuit board not only when the molten solder is stationary but also when it is continuously blown up. Compared to a soldering tank that can only perform soldering in either stationary state, its range of use is dramatically expanded.

[Brief explanation of drawings]

1 is a plan view showing an example of a solder tank according to an embodiment of the present invention, FIG. 2 is a front view showing the solder tank shown in FIG. 1, and FIG. 3 is a side view showing the solder tank shown in FIG. 4 is an enlarged plan view showing the chamber of the solder bath shown in FIG. 1, and FIG. 5 is a sectional view taken along the line ``--'' in FIG. DESCRIPTION OF SYMBOLS 1... Outer tank, 2... Chamber, 6... Inlet of chamber, 7... Outlet of chamber, 8... Rotating blade, 11... Passage in chamber, 12... Communication part,
13...Blocking wall, 14...Cover plate, 15...Air introduction hole.

Claims (1)

[Claims] 1. A chamber consisting of a suction part having a suction port for molten solder and equipped with a rotary blade, a blowout part forming a wide-area blowout port, and a communication part communicating from the suction part to the blowout part is attached to the outer tank. The communication section of the chamber includes a blocking wall extending from the bottom of the chamber to approximately the height of the outlet, and a cover plate extending from the suction section over the blocking wall to a position below the outlet. A passage for the molten solder is formed from the inside of the suction part to a position above the blowout port to the inside of the blowout part, and a small air introduction hole is formed in a portion of the passage above the blowout port. A soldering bath characterized by being provided in.