JPH0373156B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for soldering printed circuit boards, and in particular, when soldering chip-type electronic components to one side of a printed circuit board, holes for lead wires are formed on the printed circuit board. The present invention relates to a method and apparatus for soldering a printed circuit board, which enables good soldering when there is no gap.

Conventionally, when soldering electronic components with lead wires to a printed circuit board, for example, when soldering by the flow soldering method as shown in Figs. Drill a hole, attach the electronic component 3 to the top surface of the printed circuit board 1, insert the lead wire 2 into the hole and make it protrude from the bottom surface, apply flux to the bottom surface including the lead wire, and then insert it in the direction of arrows A and B. Soldering was performed by bringing waves of molten solder 4 flowing upward and into left and right directions in the figure into contact with the lower surface of the printed circuit board 1 moving in the direction of arrow C. In this case, printed circuit board 1
The flux applied to the lower surface generates a large amount of flux gas when it comes into contact with the waves of molten solder 4, but the flux gas is discharged upward from the hole for the lead wire 2. Therefore, contact between the part to be soldered and the molten solder 4 is not hindered, and soldering can be performed satisfactorily.

However, recently, in order to reduce the weight and size of the printed circuit board 1, chip-type electronic components 3a without lead wires, as shown in FIG. 3, have been increasingly used. Since such a printed circuit board 1 does not have a hole for the lead wire 2, when the electronic components 3a are soldered using the flow soldering method, some of the generated flux gas stagnates between the electronic components 3a. There is a drawback that contact between the parts to be soldered and the molten solder 4 is obstructed, resulting in many parts not being soldered.

In order to eliminate these drawbacks, jet soldering has been adopted, and in this method the flux gas is eliminated by a jet of molten solder jetted in the direction of arrow D as shown in Figure 4. Since the soldering is done by using the
As shown in FIGS. 6 to 6, a phenomenon often occurs in which surplus solder 4a adheres to the lead wire 2 of the electronic component 3 or to the chip-type electronic component 3a and hardens into a flag shape as shown in the figure. There is a drawback that the surplus solder 4a causes a short circuit between the plurality of lead wires 2 of the electronic component 3 or between the chip-type electronic components 3a, and a large amount of manual labor is required to remove the surplus solder 4a. The drawback was that productivity was extremely low.

This phenomenon is caused by the fact that in jet soldering, molten solder 4 is instantaneously sprayed onto the soldered part at a considerable speed, and the excess solder 4a adhering to the soldered part does not fall off. The printed circuit board 1 is molten solder 4 with the excess solder.
This is thought to occur because the excess solder moves outside the jet stream in the direction of arrow E, and the excess solder is cooled and solidified.

In addition, the solder jetting device for a soldering machine disclosed in Japanese Patent Publication No. 44-21622 does not have a flow rate adjustment plate or rectifying plate in any of the conduits through which molten solder flows, and it is impossible to put it into practical use as it is. It was not something that could be changed.

The present invention has been made to eliminate the drawbacks of the prior art described above, and its purpose is to provide only the advantages of jet type soldering equipment and flow soldering type soldering equipment, and to The purpose of the present invention is to provide a printed circuit board soldering device which has a synergistic effect due to its advantages, and which enables the soldering of flux and molten solder when soldering electronic components to a printed circuit board without holes for lead wires. Flux scum generated due to contact can be removed by jet type soldering equipment,
In addition, by using flow soldering type soldering equipment, excess solder adhering to electronic components is melted, and all parts that require soldering are completely soldered without excess or deficiency, improving soldering performance. It is about trying to improve. Another object is to provide an adjustment plate for adjusting the flow rate of molten solder in the injection pipe of a jet type soldering device.
It is possible to adjust the injection amount of molten solder. Still another purpose is to bend a single metal plate in a Z-shape vertical cross section in a flow soldering type soldering device to form a plurality of small holes to provide a predetermined flow resistance to flowing molten solder. By arranging the adjustment member so as to give the same, although it has a simple structure, it actually acts as three adjustment members, and the molten solder waves generated by the soldering device can be reduced. The purpose is to stabilize and make the height uniform and to enable molten solder to be jetted at a predetermined speed from a jet type soldering device.

In short, the present invention includes a solder tank, a rotating device disposed in the solder tank, a rotary blade that is rotated by the rotating device to flow the solder in the solder tank, and a rotary blade that is rotated by the rotating device to flow solder in the solder tank. In order to adjust the amount of flowing molten solder, the molten solder is discharged from the nozzle by an adjustment plate which is arranged so that its tip protrudes inside the injection pipe and is movable up and down by an adjustment screw screwed in a vertical direction. A jet type soldering device is configured to spray the solder onto the printed circuit board, and a plurality of holes are formed by bending a single metal plate so that the vertical cross section is Z-shaped to provide a predetermined flow resistance to the flowing molten solder. The molten solder flowing by the rotary blade forms a molten solder wave, and the printed circuit board, which has been soldered by the jet soldering device, is brought into contact with the molten solder wave and soldered again. The present invention is characterized in that it includes a flow soldering type soldering device configured to perform soldering.

The present invention will be explained below based on embodiments shown in the drawings. In the present invention, as shown in FIGS. 8 and 10, the printed circuit board 1 is transported upwardly to the right in the figure by the chain 8, and the soldering device 9 according to the present invention It is attached to an automatic soldering device 10, and includes a solder tank 11 and a rotary blade 1.
2, a rotating device 13, a jet type soldering device 14, and a flow soldering type soldering device 15.
It is equipped with

The solder tank 11 is filled with solder 4, and the solder 4 is melted by a plurality of electric heaters 18 housed in the solder tank. The rotary blade 12 is a partition member 19 formed inside the solder tank 11.
A plurality of rotary blades are arranged inside the rotary blade, and the rotary blades are rotated by a rotating device 13 only when the solder 4 is heated and melted, and the molten solder flows.

The rotating device 13 includes a motor 20 fixed to the solder tank 11, a frame 21 mounted so as to be inclined at a certain angle with respect to the width direction of the solder tank 11, and a frame 21 whose movement in the axial direction is restricted by the frame. It consists of a drive shaft 22 rotatably supported by a motor, a drive pulley 23 fixed to the upper end of the drive shaft, and a toothed belt 24 mounted between the drive pulley and the pulley 20a of the motor 20. ing. As shown in FIG. 9, the underframe 21 is fixed to a base plate 25 fixed to the solder tank 11 with four mounting screws 26.
The elongated hole 25a formed at the upper and lower left side of the solder tank 11 allows the solder tank 11 to be tilted at a constant angle in the width direction, thereby making it possible to change the flow direction of the molten solder 4 up and down as appropriate. It's getting old.
Further, the rotor blade 12 is fixed to the lower end of the drive shaft 22.

A sensor (not shown) for detecting the temperature of the molten solder 4 is installed inside the solder bath 11, and the sensor is connected to a control device (not shown) for controlling ON/OFF of the motor 20. There is. And solder 4
is heated by an electric heater 18, and when the temperature exceeds a certain level, a sensor detects the temperature and activates a control device to rotate the motor 20. Therefore, since the rotor blade 12 does not rotate until the solder 4 melts and becomes flexible, there is no risk of damage to components such as the rotor blade.

The jet type soldering device 14 has a partition member 1
9, and the tip of the injection pipe is a nozzle 30a. Further, inside the injection pipe 30, a plurality of adjustment screws 31 with right-hand threads are vertically screwed, and an L-shaped adjustment plate 32 for adjusting the flow rate of the molten solder 4 is disposed such that the tip thereof protrudes. ing.

The flow soldering type soldering device 15 includes an adjustment member 36 formed by bending a single metal plate in a Z-shape in vertical cross section, in an upper member 35 that communicates with the partition member 19. A plurality of small holes 36a are formed to provide a predetermined flow resistance to the flowing molten solder 4.

Further, as shown in FIG. 10, on the upper left and right side surfaces of the upper member 35 in the figure, wave height and waveform adjusting plates 37 are provided to adjust the height and shape of the waves of the molten solder 4.
38 is fixed by a mounting screw 39 so as to be adjustable in the vertical direction.

In one process of soldering the electronic component 3a to the printed circuit board 1, the molten solder 4 is sprayed onto the lower surface of the printed circuit board 1 from the jet soldering device 14 in the previous step, and the flow soldering type soldering device 15 is used in the subsequent step. The soldering is performed by bringing the waves of molten solder 4 generated by the soldering process into contact with the lower surface of the printed circuit board 1.

In FIGS. 7 and 8, 40 is a control panel, 41 is a guide rail, 42 is a conveyor width variable handle, 43 is a fluxer, 44 is an air curtain, 45 is a preheater, 46 is a nail washer, and 47 is a cooling fan. , 48 are shutters, all of which are well known, and detailed explanation thereof will be omitted.

The present invention is configured as described above, and its operation will be explained below. As shown in FIGS. 9 to 11, solder 4 filled in the solder tank 11
is heated and melted by the energized electric heater 18, the temperature sensor detects a predetermined temperature of the molten solder 4, and the motor 20 is started by the control device.
A drive shaft 22 rotates via a motor pulley 20a, a toothed belt 24, and a drive pulley 23. Then, the rotor blade 12 rotates, and the molten solder 4 is sucked up into the partition plate 19 as shown by the arrow F, and the molten solder 4 is sucked up into the partition plate 19 as shown by the arrow G.
It flows laterally as shown by arrows H and J, and further flows into the injection pipe 30 and the adjustment member 36 as shown by arrows H and J, respectively. At this time, the molten solder 4 passes through the plurality of small holes 36a of the adjustment member 36 and flows upwardly and to the left and right in the figure as shown by arrows M and N while being subjected to flow resistance, thereby performing flow soldering. A wave of solder 4 of the formula is formed. Further, due to the flow resistance, the height of the waves of the solder 4 is stabilized, and the height in the width direction is made uniform. Note that the height and shape of the waves of the molten solder 4 can be adjusted by adjusting the heights of the wave height and waveform adjusting plates 37 and 38, respectively.

Further, due to the flow resistance of the molten solder 4 by the adjustment member 36, the pressure inside the injection pipe 30 increases, and a certain amount of molten solder 4 flows into the injection pipe, as shown by the arrow K from the nozzle 30a of the injection pipe. Molten solder 4 is injected at a predetermined speed.

Note that if the amount of molten solder injected from the nozzle 30a of the injection pipe 30 is too large, loosen the adjustment screw 31. Then, the tip 32a of the adjusting plate 32 moves down, the passage of the molten solder 4 in the injection tube 30 becomes narrower, and the amount of molten solder 4 injected becomes smaller. Conversely, if the amount of molten solder 4 to be sprayed is small, tightening the adjustment screw 31 will raise the tip 32a of the adjustment plate 32, widening the passage of the molten solder 4 in the injection pipe 30, and increasing the amount of molten solder 4.
The amount of injection increases.

In FIG. 10, one step of soldering the chip-type electronic component 3a attached to the bottom surface of the printed circuit board 1 moving in the direction of arrow P will be explained. First, in the previous step, the jet type soldering device 1
The molten solder 4 is sprayed onto the electronic component 3a of the printed circuit board 1 from the nozzle 30a of the spray pipe 30 of No. 4. Then, the flux gas stagnant on the electronic component 3a is removed by the jet of molten solder 4, so that the electronic component 3a is reliably soldered. At this time, excess solder 4a adhering to the electronic component 3a is melted by waves of molten solder 4 formed by the adjustment member 36 and wave height waveform adjustment plates 37 and 38 of the flow soldering type soldering device 15 in a later process. At the same time, the soldered parts that were insufficiently soldered in the previous process are soldered more reliably.

In this way, in one step of soldering the chip-type electronic component 3a to the printed circuit board 1, flux gas is removed by the jet of molten solder 4 sprayed from the jet soldering device 14 in the previous step, and the electronic component is soldered. 3a, the excess solder 4a adhering to the electronic component will be melted away by the waves of molten solder 4 formed by the flow soldering type soldering device 15 in the subsequent process, so the experiment was conducted. As a result, it was found that it was possible to perform almost 100% perfect soldering.

Since the present invention is constructed and operates as described above, it is possible to solder a printed circuit board by having only the respective advantages of a jet type soldering apparatus and a flow soldering type soldering apparatus, and having a synergistic effect due to the advantages. When soldering electronic components to a printed circuit board that does not have holes for lead wires, the jet soldering device eliminates flux gas generated by contact between flux and molten solder. In addition, by using a flow soldering type soldering device, excess solder adhering to electronic components can be melted.
It is possible to perform complete soldering on all parts that require soldering, with the effect that soldering performance is significantly improved. In addition, an adjustment plate is installed in the injection tube of the jet soldering device to adjust the fluidity of the molten solder using an adjustment screw screwed in the vertical direction, so the amount of molten solder sprayed can be adjusted as desired. You can get the desired effect. In addition, in the flow soldering type soldering device, a vertical cross section is formed by bending a single metal plate in a Z shape, and a plurality of small holes are formed to provide a predetermined flow resistance to the flowing molten solder. Since the adjustment member is arranged, it can actually act as three adjustment members even though it has a simple structure, so the height of the molten solder wave generated by the soldering device can be reduced. This has the effect that it can be stabilized and uniformized, and that the molten solder can be jetted from the jet soldering device at a desired speed.

[Brief explanation of drawings]

Figures 1 to 6 relate to conventional examples, and Figure 1 shows the state in which electronic components are soldered to a printed circuit board with holes for lead wires made using a flow soldering type soldering device. Figure 2 is a side view when the printed circuit board moves in the horizontal direction; Figure 2 is a side view when the printed circuit board moves upward to the right in Figure 1; Figure 3 is a side view of the board shown in Figure 2, with holes for lead wires being drilled. Figure 4 is a side view of soldering chip-type electronic components to a printed circuit board that has no lead wire holes. Figure 5 is a side view when the printed circuit board moves upward to the right to show the state, and Figure 5 is a side view when chip-type electronic components are soldered to the printed circuit board shown in Figure 4 but without holes for lead wires. 6 is a plan view showing the bottom surface of a printed circuit board with excess solder attached to chip-type electronic components, FIGS. 7 to 11 relate to embodiments of the present invention, and FIG. FIG. 8 is a plan view of the automatic soldering device shown in FIG. 7, FIG. 9 is a perspective view of the soldering device, and FIG. 10 is a side view of an automatic soldering device equipped with such a soldering device. FIG. 9 is a longitudinal cross-sectional view taken along the arrow XI in FIG. 1 is a printed circuit board, 4 is molten solder, 9 is a soldering device, 11 is a soldering bath, 12 is a rotating blade, 13 is a rotating device, 14 is a jet type soldering device, 15 is a flow soldering type soldering device, 31 32 is an adjustment screw, 32 is an adjustment plate, 32a is a tip, 36 is an adjustment member, and 36a is a small hole.

Claims (1)

[Claims] 1. A solder tank, a rotating device disposed in the solder tank, a rotary blade rotated by the rotating device to cause the solder in the solder tank to flow, and molten solder flowing by the rotary blade. In order to adjust the flow rate of the molten solder, the molten solder is applied to the printed circuit board from the nozzle. A jet type soldering device that sprays solder, and an adjustment member that is formed by bending a single metal plate so that the vertical cross section is Z-shaped and has a plurality of holes that provide a predetermined flow resistance to the flowing molten solder. , forming a molten solder wave with molten solder flowing by the rotary blade, and bringing the printed circuit board, which has been soldered by the jet soldering device, into contact with the molten solder wave to perform soldering again. 1. A printed circuit board soldering device comprising: a flow soldering type soldering device configured as shown in FIG.