JPS595390B2 - solder tank - Google Patents

Description

[Detailed description of the invention] - The invention relates to a soldering device for printed circuit boards, etc.
In particular, it relates to a soldering device for printed circuit boards on which chip components are mounted.

A jet soldering method is generally used as a method for soldering components mounted on a printed circuit board. The jet soldering method is a method of soldering by spraying molten solder onto the soldering surface of a printed circuit board while moving it. Figures 1 and 2 show the most common jet solder wave shape as a conventional example. It shows. However, this kind of solder wave shape is
In particular, it has the following drawbacks when soldering printed circuit boards on which chip components such as chip resistors or chip capacitors are mounted.

The solder wave shape in FIG. When the printed circuit board 4 is separated from the printed circuit board 4, the solder wave 2
Since the solder flows down in the same direction as the moving direction of the solder, the excess solder adheres to the object to be soldered and is rapidly cooled, so that the soldered chip component 3 becomes an icicle-like overlay 5 as shown in FIG. 1c. Put it away.

This icicle-like build-up may become a short build-up 9 shown in FIG. 2 between adjacent chip parts. Next, in order to prevent this icicle-like defect, the solder wave shape shown in FIG. 1b was devised.

This solder wave shape flows as a solder wave 2 from the nozzle 1 to the left, that is, in the opposite direction to the traveling direction of the printed circuit board 4, and the printed circuit board 4 is tilted upward with respect to the traveling direction to cause the solder wave 2 to flow. is passing. Indeed, with this method, when the printed circuit board 4 separates from the solder wave 2, the solder wave 2 flows down in the opposite direction to the traveling direction of the printed circuit board 4, preventing excess solder from adhering to the object to be soldered, and creating an icicle. The shaped overlay 5 does not occur. However, since the solder wave 2 acts only on one side of the chip component 3, that is, from the right to the left, as shown in FIG. In case of 611C, a normal solder overlay 7 can be obtained, but the rear part 8 may not be soldered at all. Therefore, the present invention aims to obtain good quality of these chip parts without causing soldering defects.

Hereinafter, a detailed explanation will be given according to the drawings. 4 to 6 show specific examples, 9 in FIG. 4 is a bending point in nozzle 1, 10 in FIG. 5 is a curved surface of nozzle 1, and 11 in FIG. part, 12
13 is an outlet formed by deforming the nozzle 1 into a protruding shape in the width direction, and in Fig. 8, 13 is an outlet formed by deforming the central nozzle into a letter shape in the width direction. It's a heater.

In FIGS. 3 and 4, the tangent angle α at the bending point 9, β shown in FIG. 5, and γ shown in FIG. , 2 and ~80 angles are appropriate.

When α, β, and γ are smaller than 2, it is the same as a normal jet flow, and the pressure attacking the electrode portion of the component becomes small. Also α, β, γ
If the value is larger than 800, a problem arises in that the nozzle end comes into contact with chip parts adhered to the printed circuit board. It is more preferably between 5 and 60. Furthermore, as can be seen from the table below, it was also found that the solder yield was better when the bending directions of the first nozzle and the second nozzle were opposite. However, in many cases, the mounting direction of chip components is perpendicular to the advancing direction of the printed circuit board, and the soldering method shown in Figures 7A, b and 8A, b is required for the mounting density. A tank configuration is also possible. As described above, in the present invention, the nozzle shape has a close relationship with solder defects in the same jet-flow solder tank, and in particular, by changing the solder flow from the nozzle, solder defects were significantly reduced.

This has great effects on line work in terms of reducing the number of correction steps, improving the reliability of wiring boards, and saving energy.

[Brief explanation of the drawing]

Figure 1 A, b, c, d are conventional jet nozzles, Figure 2 is
A schematic diagram showing the cause of the non-solder area 6 caused by chip components and solder flow, FIG. 3 is a schematic cross-sectional view of the solder tank of the present invention, and FIG. 4 is an enlarged cross-sectional view of the nozzle portion of FIG. 3. 5 and 6 are cross-sectional views of nozzles according to other embodiments of the present invention,
7A and 7B are schematic cross-sectional views of the solder bath of the present invention, and FIG. 8A
, b are plan views showing the nozzle shapes and their arrangement in FIGS. 7A and 7b. 1...nozzle, 2...solder, 7...
...Pressure supply device.

Claims (1)

[Claims] 1. It has at least two or more solder outflow nozzles, the solder wave of the first nozzle flows out at least in the traveling direction of the printed circuit board, and the second nozzle at least flows out the solder wave of the printed circuit board. In a solder bath where the flow is in the opposite direction to the direction of travel and the direction of conveyance of the printed circuit board is inclined upward in the direction of travel,
The shape of the first nozzle and the second nozzle has at least one bent part in the middle of the nozzle when viewed from the side, and at least one of the bent parts The solder tank is located on the leftmost side of the nozzle in the solder tank cut in the direction of gravity, and the bending angle of the solder tank is bent in the direction of movement of the printed circuit board. 2. The solder bath according to claim 1, wherein the at least one bent portion is formed at an angle of 2 to 80 degrees with respect to a direction opposite to gravity. 3 When there are two or more bent portions, at least the second bent portion is provided in the second nozzle, and its position is at the end of the nozzle in the solder bath in the cross section cut in the direction of gravity in the direction of travel of the printed circuit board. 3. The solder bath according to claim 1, wherein the solder bath is located on the right side, and the angle at which the bent portion is formed is opposite to the direction of movement of the printed circuit board.