JP2607524B2 - Convection type vapor soldering equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a convective gas-phase soldering apparatus suitable for application to soldering a surface mount component to a printed circuit board.

[Related Art] When reflow soldering a surface mount component to a printed circuit board, an infrared soldering device, a hot plate soldering device, a laser soldering device, a vapor phase soldering device, and the like are generally used.

Among these, a batch type as shown in FIG. 3 and an in-line type as shown in FIG. 4 are known as a vapor phase soldering apparatus.

In the batch type vapor phase soldering apparatus 10 shown in FIG. 3, a predetermined solvent 2 is filled in the bottom of a tubular reflow furnace 1 as shown in the figure. A heating source 3 such as a heater is arranged on the outer surface of the bottom of the reflow furnace 1, whereby the solvent 2 is vaporized.

As the solvent, a fluorinated solvent such as Fluorinert is used.

A cooling source 4 composed of a cooling coil or the like is attached to the upper opening side of the reflow furnace 1. In the reflow furnace 1, the printed circuit board 6 on which the surface mounting components 7 are temporarily fixed by the elevating means 5 can be moved up and down.

Here, by heating the heating source 3, the solvent 2 is vaporized. In this case, the printed circuit board 6 on which the surface mount components 7 are placed is located in a high temperature atmosphere between the liquid surface and the vapor interface. The lifting / lowering means 5 is controlled.

By positioning the printed circuit board 6 within the vapor interface in such a high-temperature atmosphere, the paste solder attached to the dielectric layer of the printed circuit board 6 is melted, and the surface mount component 7 is soldered to the printed circuit board 6. You. After the soldering, the printed circuit board 6 is pulled up by the lifting means 5 out of the vapor interface to be cooled.

As a result, the solder paste is solidified and the surface mount component 7 is securely fixed to the printed circuit board 6.

On the other hand, in the in-line type gas-phase soldering apparatus 10, as shown in FIG.
The transport belt 12 is attached to be able to advance and retreat so as to pass through.

The printed circuit board 6 is transported in the reflow furnace 1 while being placed on the transport belt 12.

The cooling coil 4 functioning as a cooling source is attached to the inlet side and the outlet side of the transport hole 11.

In this configuration, the transport belt runs inside the vapor interface of the solvent 2.
The grounding position of the conveyor belt is selected so that 12 passes.

[Problems to be Solved by the Invention] By the way, in the gas-phase soldering apparatus configured as described above, a batch-type configuration as shown in FIG.
This involves raising and lowering the printed circuit board 6 by the lifting / lowering means 5 and thereby soldering.
Not suitable for mass soldering.

Further, when soldering, the printed board 6 must be suspended at a position where the printed board 6 is completely buried in the vapor interface.

As a result, the surface-mounted component 7 itself is also turned into steam, so that, for example, in the case of a surface-mounted component that is susceptible to heat, the surface-mounted component may be thermally broken.

On the other hand, in the in-line type vapor phase soldering apparatus 10 as shown in FIG. 4, since the soldering process can be performed with a plurality of printed circuit boards 6 placed on the transport belt 12, a large amount It is suitable for processing.

However, in this configuration, the transport belt 12 is selected to have a positional relationship such that it passes through the upper end of the vapor interface. This is because, when the vapor rises further, the raised vapor flows out to the outside through the transport hole 11, and the waste of the solvent 2 becomes extremely large.

Therefore, since it is necessary to perform the soldering process in an unstable temperature region near the vapor interface, there is a possibility that an accident such as poor solder joint may occur.

Further, also in this configuration, the surface-mounted component 7 mounted on the printed circuit board 6 is exposed to the solvent 2 in the vapor interface as in the case of FIG. It is not suitable as the attaching process.

In view of the above, the present invention solves all of the conventional problems described above, and enables mass processing, prevents destruction of surface mount components due to heat, and minimizes outflow of steam. The present invention proposes a convective gas-phase soldering apparatus described above.

[Technical Means for Solving the Problems] In order to solve the above problems, in the present invention,
A reflow furnace filled with a solvent at the bottom as a convective gas-phase soldering device, a belt that conveys a printed circuit board in a solvent atmosphere in the reflow furnace, and a bottom surface of the printed circuit board conveyed by the belt, and It consists of a vapor guide tube with multiple funnel-shaped openings arranged in the direction of transport of the printed circuit board, and the solvent vapor is blown out from the multiple guide tubes toward the bottom surface of the printed circuit board, and the surface mounted on the printed circuit board It is characterized in that parts are soldered.

[Operation] In this configuration, as shown in FIG. 2, the vapor of the solvent 2 rises upward through the guide cylinder 20. And this guide cylinder 20
The steam blows from the plurality of tip openings 21A, 21B, 21C toward the lower surface of the conveyor belt 12. As a result, the vapor comes into contact only with the lower surface of the printed circuit board 6.

Further, since the cooling coil 4B is wound around the reflow furnace 1 facing the front end opening 21, the steam flowing out of the guide cylinder 20 is immediately cooled.

As a result, the ejected vapor descends along the outer circumference of the guide cylinder 20, and the vapor interface of the solvent 2 becomes a state as shown in FIG. 1 or FIG. Fear is negligible.

Further, by arranging the plurality of tip openings 21A, 21B, 21C along the belt 12, the printed board 6 can be heated uniformly.

Since this configuration is of a conveyor belt type, a large amount of soldering processing can be performed.

[Embodiment] Next, an example of a convective gas-phase soldering apparatus according to the present invention will be described in detail with reference to FIG.

As shown in FIG. 1, a convective gas-phase soldering apparatus 10 according to the present invention, as shown in FIG. The heating source 3 is arranged on the outer surface of the bottom of the heating source.

This reflow furnace 1 is composed of a cylindrical body whose upper end is closed,
A transport hole 11 for transporting the transport belt 12 is attached near the upper end. A cooling coil 4A is also wound around the transfer hole 11, and the cooling source 4 is constituted by the cooling coil 4A and the cooling coil 4B wound around the reflow furnace 1.

Inside the reflow furnace 1, a funnel-shaped steam guide cylinder 20 is disposed, and its tip opening is formed in a funnel shape so that the tip opening 21 faces the conveyor belt 12 at a predetermined distance. The working positional relationship between the conveyor belt 12 and the steam guide cylinder 20 is selected.

Liquid guide holes 22 and 23 having a predetermined diameter as shown are provided in a part of the guide cylinder 20 immersed in the solvent 2.
0 Smooth liquid flow inside and outside.

In the convective gas-phase soldering apparatus 10 thus configured, the solvent 2 is vaporized by operating the heating source 3. The steam mainly rises in the guide cylinder 20. Since the raised steam is ejected upward through the tapered tip opening 21, the steam is intensively spouted on the lower surface of the belt 12 conveyed to face the tip opening 21.

As a result, the printed circuit board 6 placed on the transport belt 12
The paste solder attached between the substrate and the surface mount component 7 is melted by the high-temperature steam of the solvent 2. The printed circuit board 6 in the molten solder state is further conveyed and discharged to the left, and as a result, is cooled and the solder is solidified, whereby the surface mount component 7 is reliably soldered on the printed circuit board 6.

The steam jetted from the end opening 21 side falls as shown by the arrow. At this time, a cooling coil 4B is provided on the outer surface of the reflow furnace 1.
Which cools the steam,
Most of the cooled steam descends along the outer peripheral surface of the guide cylinder 20.

Therefore, the vapor interface forms a similar-shaped interface of the guide cylinder 20 having a substantially funnel shape as shown in the figure.

The steam that has fallen on the outer surface of the guide cylinder 20 is liquefied by being further cooled, and the solvent 2 is reused by such convection of the solvent 2. The solvent 2 inside and outside the guide cylinder 20 circulates through the liquid flow holes 22 and 23.

Here, the transport belt 12 is slightly below the top of the vapor interface.
If the positional relationship between the vapor interface and the transport belt 12 is selected so that the air passes through, the printed circuit board 6 placed on the transport belt 12 can be sufficiently heated.

On the other hand, unnecessary heat is not applied to the surface mount component 7 mounted on the upper surface. As a result, the surface mount component 7 can be effectively protected from heat, and only the intended paste solder can be melted.

In the case where the vapor of the solvent 2 is jetted through the tip opening 21, the temperature of the jetted vapor becomes almost constant, so that the melting at the unstable vapor interface as shown in FIG. It is not necessary to perform the soldering process. Accidents such as poor solder joints can be prevented beforehand by the soldering process at the constant temperature steam interface.

By providing the cooling coil 4B in the reflow furnace 1 itself, the steam interface can be formed in a funnel shape as shown in the figure. Thus, the possibility that the steam flows out through the transport hole 11 to the outside is reduced. As a result, the solvent can be used effectively.

The above-described guide tube 20 may have a plurality of distal opening portions 21 instead of a single opening portion.

FIG. 2 shows an example of such a case, in which a plurality of tip openings 21A, 21B, 21C are provided in parallel in the transport direction of the transport belt 12. Even in such a case, each of the distal end openings is formed in a funnel shape.

With this configuration, the printed circuit board 6 can pass through the vapor interface for a sufficient time, and can also prevent uneven heating of the printed circuit board 6 by ejecting steam from the plurality of tip openings 21A, 21B, and 21C. . Therefore, the printed circuit board 6 can be heated sufficiently and uniformly, so that the paste solder is completely melted, and accidents such as poor bonding of the solder are eliminated.

[Effects of the Invention] As described above, in the present invention, the funnel-shaped steam induction cylinder is provided in the reflow furnace, and therefore has the following features.

First, a large amount of solder processing can be performed because of the conveyor belt system.

Second, because the printed circuit board on which the surface mount components are mounted is not configured to pass through the inside of the vapor interface,
Surface mount components can be effectively protected from heat. As a result, even when thermally weak surface mount components are soldered, it is possible to effectively protect these surface mount components.

Third, since the vapor interface can be made funnel-shaped by providing the guide cylinder, the outflow of the solvent can be suppressed as much as possible. This makes it possible to significantly reduce running costs.

Fourth, by ejecting steam from a plurality of funnel-shaped openings arranged in the direction along the belt, it is possible to prevent uneven heating of the printed circuit board. Therefore, the printed circuit board can be sufficiently and uniformly heated, so that accidents such as poor solder joints are eliminated.

Because of the features described above, the present invention is extremely suitable for application to a vapor phase soldering apparatus for soldering a surface mount component.

[Brief description of the drawings]

1 and 2 are configuration diagrams showing an example of a convection type vapor phase soldering device according to the present invention, FIG. 3 is a configuration diagram of a conventional batch type vapor phase soldering device, and FIG. It is a block diagram of a vapor-phase soldering apparatus. DESCRIPTION OF SYMBOLS 1 ... Reflow furnace 2 ... Solvent 3 ... Heating source 4 (4A, 4B) ... Cooling source 6 ... Printed circuit board 7 ... Surface mount components 10 ... Vapor phase soldering device 20 ... Induction cylinder 21 ( 21A ~ 21C) ... Tip opening

Claims (1)

(57) [Claims] A reflow furnace having a bottom filled with a solvent, a belt for transporting a printed circuit board in a solvent atmosphere in the reflow furnace, a bottom surface of the printed circuit board transported by the belt, and A vapor guide tube having a plurality of funnel-shaped openings arranged in the direction of transport of the printed circuit board, and the vapor of the solvent is ejected from the plurality of guide tubes toward the bottom surface of the printed circuit board and mounted on the printed circuit board. A convective gas-phase soldering apparatus characterized in that a surface-mounted component is soldered.