JPH0327301B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a jet solder bath having primary and secondary injection nozzles.

Problems to be Solved by the Invention The printed circuit board coated with flux is preheated in a preheater, the resin is sintered to improve soldering, and the alcohol is evaporated at the same time, and then solder is welded in a soldering bath. .

However, in the case of a high-density printed circuit board, a gas vent hole is provided in the board itself, and gas is removed from the gas vent hole.

When soldering is carried out using a jet of solder melt on such a printed circuit board, the parts that are behind the chip components with respect to the running direction of the printed circuit board,
The parts where each chip part is close to each other are concave,
Since air and other gases remain in this area and the solder melt does not flow in, the solder melt does not adhere to the area, or even if it does adhere, a hollow portion is formed and complete adhesion cannot be achieved. If bubbles are generated during one soldering process, there is a drawback that the bubbles cannot be removed even if a jet of solder melt is applied for a long period of time.

Further, electronic components are arranged vertically and horizontally on a printed circuit board, and it is difficult to weld solder evenly all over the board, especially in the case of chip components.

Furthermore, there are solder baths that have a primary and secondary jet tank, but they are expensive due to their complicated structure, and in this case, a pump is attached to each jet tank, so there is a drawback that the ejection wave is not constant.

Therefore, it is an object of the present invention to provide a jet-flow type solder tank that eliminates the above-mentioned drawbacks.

Means for Solving the Problems In order to achieve the above object, in the jet type solder tank of the present invention, the solder tank 2 is connected to the upper and lower parts 5a, 5 through the partition plate 5.
b, and the partition plate 5 has a solder inflow hole 51.
A pump 6 whose discharge pressure to the solder inflow hole 51 can be changed is arranged in the lower part 5b, and a primary jet tank 3 and a secondary jet tank 4 are installed in sequence in the direction of conveyance of printed circuit boards that are transported at a constant angle. In the jet type soldering tank, the primary jet tank 3 is provided with a recess 34 in the center of the top surface for discharging the spouted solder liquid, and on both sides of the recess 34 are left and right rows of discharge holes whose positions are shifted from each other. 32 and 33 are provided, and a perforated plate 31 is installed parallel to the running direction of the printed circuit board 9 to prevent interference and disturbance of the solder liquid. The opening surface 41 is formed to be a horizontal surface in order to promote cooling, and a flow rate regulating valve 42 is provided inside the tank 4.

Embodiment An embodiment of the present invention will be described below based on the drawings.

In the figure, reference numeral 1 denotes a jet-flow type solder bath device, in which a printed circuit board 9 is moved at a constant speed over the solder bath 2 with the solder welding surface 91 facing down by a carrier attached to a conveyance chain at a constant angle of inclination. It is something that is transported.

This solder tank 2 is divided into an upper part 5a and a lower part 5b by a partition plate 5. A primary jet tank 3 and a secondary jet tank 4 are sequentially installed in the upper part 5a in the running direction of the printed circuit board 9, and in the lower part 5b. has a schematic configuration in which a pump 6 is installed.

A bearing 52 is provided on one side of the partition plate 5, and a solder inflow hole 5 is provided around the bearing 52.
1 are provided in large numbers.

Further, on the other side of this partition plate 5, a primary jet tank 3 is provided.
and a secondary jet tank 4 are installed side by side in an upright manner.

The head of the primary jet tank 3 is formed to be slightly tapered, and the opening surface of the head is aligned with the running direction of the printed circuit board 9.
is formed parallel to.

This head opening surface has discharge holes 32 and 33 on both sides of this recess 34 through the central recess 34.
A perforated plate 31 provided with rows is attached.

These discharge holes 32 and 33 are provided so that the left side discharge hole 33 and the right side discharge hole 32 are shifted in position.
The diameter of the discharge holes 32 and 33 is, for example, about 3 to 8 mm.

Note that this porous plate 31 is attached to the opening surface of the head parallel to the running direction of the printed circuit board 9.

Further, the secondary jet tank 4 has a head opening surface 41 formed in a horizontal plane, and a flow rate regulating valve 42 that controls the discharge flow via a bearing 43 is provided on the inner wall 44 of the secondary jet tank 4.
is provided.

A drive shaft 7 to which a motor 8 is attached is attached to the lower part 5b of the solder bath 2 via a bearing 52.
A pump 6 is attached via this drive shaft 7.

This pump 6 generates static pressure within the lower chamber (chamber) 5b.

In the figure, 5c is molten solder liquid.

Operation: The molten solder liquid is sucked in by the drive of the pump 6 and is sent at a constant flow rate from the solder inflow hole 51 to the primary jet tank 3 and the secondary jet tank 4 through the lower part (chamber) 5b as shown by the arrow. .

In the primary jet flow tank 3, the molten solder liquid is discharged from the discharge holes 32 and 33 at a constant flow rate, and is ejected so as to hit the welding surface of the printed circuit board 9.

At this time, vertical and horizontal concave and convex waves from the discharge holes 32 and 33 whose positions are shifted from each other impinge on the solder welding surface with a constant discharge pressure without interfering with each other.

After the solder melt is evenly applied to the solder welding surface 91 in the primary jet tank 3, the solder is neatly applied by flat waves in the secondary jet tank in the next step, as if licking the surface. Additionally, excess solder is removed in this secondary jet tank 4.

Note that the discharge hole pressure of the solder solution is set by the motor 8 according to the shape and arrangement of the electronic components mounted on the printed circuit board 9.

Effects of the Invention According to this invention, the welding surface of a printed circuit board is degassed by uneven waves of molten solder that is intermittently spouted without interference or disturbance of the solder in the primary jet tank, and is roughened at the same time. Then, in the next step, a secondary jet tank, the solder is soldered by licking the surface with a flat solder wave flow, and in this step, the solder is sharpened and excess solder is removed.

Therefore, even in the case of a high-density printed circuit board that does not have gas vent holes, the gas is vented during this rough soldering process, so that soldering can be performed perfectly and the quality is improved.

Further, when the solder passes through the primary and secondary jet tanks, it is completely soldered and excess solder is removed from the welding surface, so that soldering defects such as icicles, bridging, and non-wetting of the solder do not occur.

Furthermore, the lower part (chamber) is equipped with a pump whose discharge pressure can be changed by a single motor, and in the secondary jet tank, the flow pressure can be adjusted with a flow control valve, so the structure is simple and can be manufactured at low cost. Maintenance is also easier.

Further, since the primary and secondary jet tanks are operated by one pump, there is no unevenness in the discharge hole pressure.

[Brief explanation of the drawing]

The figures relate to embodiments of the invention, and include
FIG. 1 is an explanatory diagram of the principle of the invention, FIG. 2 is a front view of a primary and secondary jet tank, and FIG. 3 is a plan view of FIG. 2.

Claims (1)

[Claims] 1. The solder tank 2 has upper and lower parts 5a,
5b, and the partition plate 5 has a solder inflow hole 5.
1, and a pump 6 whose discharge pressure to the solder inflow hole 51 can be changed is arranged in the lower part 5b, and a primary jet tank 3 and a secondary jet tank 4 are sequentially installed in the feeding direction of the printed circuit board that is transported at a constant angle. In the attached jet type soldering tank, the primary jet tank 3 is provided with a recess 34 in the center of the top surface for discharging the spouted solder liquid, and on both sides of this recess 34, there are left and right rows of discharge holes with staggered hole positions. A perforated plate 31 provided with holes 32 and 33 to prevent interference and disturbance of the solder liquid is installed parallel to the running direction of the printed circuit board 9, and the secondary jet tank 4 is filled with the solder roughened in the primary jet tank 3. A jet-flow type solder tank characterized in that an opening surface 41 is formed in a horizontal plane to promote soldering, and a flow rate regulating valve 42 is provided inside the tank 4.