JP2500164B2 - Nitrogen-enclosed jet-type soldering device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitrogen-enclosed jet type soldering apparatus in which at least a soldering step is performed in a nitrogen atmosphere.

[0002]

2. Description of the Related Art Conventionally, a printed circuit board is generally soldered by a jet type (automatic) soldering device. FIG. 8 shows an example of a jet type soldering device.
In this soldering apparatus 1, reference numeral 2 is a conveyor for conveying an article to be soldered (for example, a printed circuit board) to be soldered. The transfer conveyor 2 is composed of two tracks 2a and 2b provided in parallel and facing each other. Soldered products are those tracks 2
It is conveyed in a state of being installed between a and 2b. Below the transport conveyor 2, the fluxer 5, the warm air heater 6, the preheater 7, the solder bath 8, along the extending direction of the transport conveyor 2 from the inlet side (front side in the drawing) toward the outlet side. The cooling fan 9 and the like are sequentially arranged.

With this configuration, the printed circuit board carried into the soldering device 1 from the entrance side of the conveyor 2 is first coated with flux by the fluxer 5 and then applied to the warm air heater 6. The flux is dried, preheated by the preheater 7, soldered in the solder bath 8, cooled by the cooling fan 9 and then carried out and moved to the next step. Will be things.

By the way, in the soldering apparatus (process) as described above, a flux containing pine resin (rosin) or a halide is conventionally used as the flux attached by the fluxer 5. If this flux remains on the printed circuit board, it may cause corrosion or a decrease in insulation resistance. Therefore, cleaning with chlorofluorocarbon or trichloroethane was performed after the soldering process. However, in recent years, it has been determined that these fluorocarbons and trichloroethane are internationally regulated as ozone-depleting substances.

Under these circumstances, recently, a soldering apparatus which does not require cleaning of flux in the soldering process of a printed circuit board has begun to be provided. It was developed from the following viewpoints. In other words, the flux is a so-called reducing agent (antioxidant), and the stronger the action, the better the original function of the flux is. However, such flux has a large amount of residue, which requires cleaning after soldering. . That is, in the soldering apparatus, the flux having a small reducing action is used to volatilize the flux in the soldering process, thus eliminating the need for cleaning the flux. When such a flux is used, it is feared that the terminals and copper foil will be oxidized before reaching the soldering part. Therefore, soldering should be performed in an inert gas (nitrogen gas) atmosphere. There is.

For example, ELECTRONIC PACKING & PRODUCTIO
In N magazine, April 1990 issue, P64-P66, in the jet type soldering machine, the whole conveying system from the fluxer to the cooling machine is covered with a cover in a tunnel shape, and nitrogen gas is supplied to almost the entire area inside the cover. A nitrogen-enclosed jet-type soldering device in which a mouth is arranged and the entire inside of the cover is made into a nitrogen atmosphere is disclosed. In this case, the oxygen concentration inside the cover that covers the entire transport system is set to about 50 ppm or less. According to the nitrogen-filled type soldering apparatus as described above, good soldering can be performed even if a flux having a small reducing action is used.

[0007]

However, as a result of earnest research, the inventors of the present invention have found that, in the nitrogen-filled jet-type soldering apparatus as described above, the entire conveying system corresponding to each step is not made to be a nitrogen atmosphere. In both cases, it was found that the soldering can be performed satisfactorily if only the part corresponding to the soldering tank to be soldered has a nitrogen atmosphere, and in that case, if the surroundings of the soldering tank have a nitrogen atmosphere with an oxygen concentration of less than 5%. Got

The present invention has been made in view of the above circumstances, and in particular, in a nitrogen-enclosed jet type soldering apparatus in which at least the peripheral portion of the solder bath is soldered in a required nitrogen atmosphere, at the time of soldering. It is another object of the present invention to provide a nitrogen-enclosed jet-type soldering device that can create more advantageous conditions.

[0009]

The invention according to claim 1 is
A conveyor that conveys the soldered product and a nozzle that is provided below the conveyor and that blows the molten solder upward.
A nitrogen-enclosed jet-type soldering device, which is configured to have a solder bath provided with a sledge, and is configured such that at least soldering to the soldered article in the solder bath is performed in a nitrogen atmosphere. , A nitrogen supply unit for supplying nitrogen gas to the vicinity of the solder tank is at least above the solder tank and below a transfer line of the soldering object to be transferred by the transfer conveyor.
And at least the transfer container with respect to the nozzle.
It is located on the front side of the carrier in the transport direction, and
It is characterized in that it extends in the width direction orthogonal to the transport direction of the feed conveyor .

[0010] The invention according to claim 2, in a nitrogen-filled nozzle-type soldering apparatus according to the claim 1, wherein
The nitrogen supply unit is orthogonal to the transfer direction of the transfer conveyor.
Pipe wall of the conduit that is provided in the width direction and through which nitrogen gas is introduced
It is characterized in that a jet hole is formed in the .

[0011]

In the nitrogen-filled jet type soldering device according to the first aspect, the space formed between the lower surface of the article to be soldered and the molten solder surface when the article to be soldered reaches the upper portion of the solder bath. Is filled with the nitrogen gas supplied from the nitrogen gas supply port. Since the space formed between the lower surface of the article to be soldered and the molten solder surface is extremely narrow, it is possible to easily create a nitrogen atmosphere having an extremely high nitrogen gas concentration on the lower surface of the article to be soldered. Nitrogen supply section is below the transfer line
In front of the solder nozzle and in the direction orthogonal to the transfer line.
Since it is provided in place, it is even and
A high-concentration nitrogen atmosphere can be reliably formed, and
It also supports changing the width of the beer.

According to a second aspect of the present invention, there is provided a nitrogen filled jet type soldering device having a simple structure.
Easy to achieve with. Also, modify the existing solder bath
No need.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment describes an example in which the present invention is applied to an apparatus for soldering a mounted printed circuit board. 1 and 2 show the vicinity of a solder bath of a nitrogen-filled jet-type soldering device 15 according to the present invention. In these drawings, reference numeral 2 (FIG. 2) is a conveyer conveyor, and 8'is a solder tank provided below the conveyer conveyor 2.

The transfer conveyor 2 has two tracks 2a and 2b provided in parallel. Each orbit 2
a and 2b have a large number of endlessly moving claws 3, 3, ..., and the printed circuit board (soldered product) P is directly gripped between the claws 3 as shown in FIG. To be done. As shown in FIG. 2, on both outer sides of the tracks 2a and 2b, frames 10 and 10 extend at substantially the same height as the tracks 2a and 2b in parallel with the tracks 2a and 2b.
The tracks 2a and 2b are supported by the frames 10 and 10, and the transfer angle of the transfer conveyor 2 is changed by changing the angles of the frames 10 and 10.

Below the transfer conveyor 2, in addition to the solder bath 8 ', a fluxer, preheater, etc. (not shown) similar to the soldering device 1 shown in FIG. 8 are provided on the front side of the solder bath 8'. A cooling fan is arranged on the rear side of the solder bath 8 '. Devices other than the solder bath 8 ', such as fluxers and preheaters, are the same as the frame 1 described above.
It is supported by 0 and 10.

However, the flux used in the nitrogen-filled jet-type soldering device 15 according to the present invention is a special flux having a small reducing action and does not require cleaning after soldering. Further, the fluxer for applying the flux to the soldering surface of the printed circuit board is of a type in which the flux is sprayed and sprayed.

The distance between the two tracks 2a and 2b, that is, the conveying width, can be changed and adjusted by a track width adjusting mechanism (not shown).

In this embodiment, the solder baths 8'are formed into two baths by the partition plate 13 in the extending direction of the conveyor 2 as shown in FIG. 1, and the first nozzle is provided for each bath. 11, and a second nozzle 12 is provided.

Nitrogen supply pipes (nitrogen supply parts) 14, 14, ... For ejecting nitrogen gas near the upper end of the solder bath 8'and below the carrier line L of the printed circuit board.
Is provided. The nitrogen supply pipe 14 is a through hole (not shown) for ejecting nitrogen gas to the wall of the metal pipe.
Is formed. These nitrogen supply pipes 14 are shown in FIG.
As shown in FIG. 3, the through hole is provided so as to extend in the width direction of the solder bath 8 ′, that is, in the direction orthogonal to the transport direction of the transport conveyor 2, and the through hole is provided above the through hole in the longitudinal direction of the nitrogen supply pipe. Many are formed along it. Further, as shown in FIG. 1, the plurality of nitrogen supply pipes 14 are arranged so as to extend almost entirely from one end to the other end with respect to the printed board moving direction in the upper part of the solder bath 8 '(left and right direction on the paper surface in FIG. 1). Are arranged, and in particular with respect to the two nozzles 11, 12, at least those nozzles 11, 12,
12 front side (front side with respect to printed circuit board conveyance direction)
These nitrogen supply pipes 14 are located in the.

A nitrogen gas generated by a nitrogen generator (not shown) is introduced into the nitrogen supply pipes 14, 14, .... In this embodiment, the nitrogen generator used in this apparatus uses a nitrogen generator utilizing membrane separation.

Further, a shield space for enclosing the nitrogen gas supplied by the nitrogen supply pipes 14, 14, ... Is formed in an upper space substantially corresponding to the solder bath 8'in the upper part of the solder bath 8 '. A shield 19 is provided for this purpose.
As shown in FIG. 1, the shield 19 includes frames 10, 1
With respect to the extending direction of 0, it is formed sufficiently longer in the front-rear direction than the length of the solder bath 8 ', and has a width between both frames 10, 10 as shown in FIG. Has been done.

As shown in FIGS. 1 and 2, the shield 19 includes an upper cover 16A provided above the conveyor 2 and a lower cover 16B provided below the conveyor 2. The upper cover 16A and the lower cover 16B are included in the shutter 30 that closes the front and rear openings of the space surrounded by the upper cover 16A and the lower cover 16B.

In this embodiment, both the upper cover 16A and the lower cover 16B are made by bending a stainless plate. As shown in FIGS. 1 and 2, the upper cover 16A includes a rectangular top plate 17 and four side plates 18a, 18b, 1 bent vertically downward from four sides of the top plate 17.
8c and 18d. These side plates 18a
The two side plates 18a, 18c that face each other are arranged in a direction orthogonal to the extending direction of the conveyor 2 (frame 10), and the other two side plates 18b, 18 that face each other.
d is oriented in the direction along the frames 10 and 10, respectively. The upper cover 16A has the side plates 18b, 18
d is attached to the outer surface 10a of the frame 10 by, for example, fixing it with a screw. Most of the top plate 17 of the upper cover 16A is composed of a transparent glass plate 22 fitted in the locking groove 21, so that the solder bath 8'can be seen from above the upper cover 16A. Has become.

The lower cover 16B corresponds to the solder bath 8 '.
Corresponding to the above, there is a bottom plate 23 having a size that covers at least the entire upper opening of the solder bath 8 '. Both ends of the bottom plate 23 (ends in the left-right direction on the paper surface in FIG. 1) rise upward, and the rising ends are bent horizontally outward to form a mounting portion 24. This mounting part 24 is the frame 1
It corresponds to 0 and 10 and is attached to the lower surfaces 10b and 10b by, for example, screws.

The portion of the bottom plate 23 corresponding to the solder bath 8'has a rectangular opening 25 as shown in FIG.
The upper surface of the solder bath 8 ′ can be seen from the opening 25. As shown in FIG. 1, the bottom plate 23 is provided with both nozzles 1
The outlets 11a and 12a are located below the outlets 11a and 12a.
Is located at a position slightly above the opening 25. However, the bottom plate 23 is located above the upper end of the outer wall of the solder bath 8 '.

As shown in FIGS. 1 and 2, shield plates 26a, 26b, 26c, and 26d project downward from the four sides of the opening 25, as shown in FIGS. It is inserted inside the solder bath 8 ', that is, in the molten solder. And this gives
The gap between the lower cover 16B and the solder bath 8'is shielded. These shield plates 26a to 26d are provided in a position close to the inner wall surface side plate of the solder bath 8'in a non-contact state with the inner wall surface.
It is well outside 12 The shield plate 2
Of the 6a to 26d, the pair of shield plates 26b and 26d provided in the extending direction of the transport conveyor 2 includes a solder bath 8 '.
Since the partition plate 13 is crossed, the portion corresponding to the partition plate 13 has a form in which the partition plate 13 is escaped by the groove 27 as shown in FIG. 1 or 4. Further, in FIG. 4, a hole indicated by reference numeral 28 is a hole formed in the shield plate 26c for passing each of the nitrogen supply pipes 14.

In this case, the shutters 30 are provided at two positions between the tracks 2a and 2b and between the track 2b and the frame 10 as shown in FIG. The shutter 30 (30A, 30B) has a plurality of screens 31,3.
1, ... Are arranged in the width direction. These screens 31 are made of a flexible film body. As shown in FIG. 6, the screens 31 have upper ends near the inner upper ends of the side plates 18a and 18c.
Guide rails 32, 32 provided in parallel with a, 18c
It engages with a groove 33 formed between and can slide along the guide rail 32. , Each screen 31 is, in this case, as shown in FIG.
The upper surface of one end 34a in the width direction of the upper bent portion 34 hooked on the guide rail 32 is hooked to the lower surface of the other end 34b of the screen 31 adjacent to the screen 31, and the adjacent screens are adjacent to each other. It prevents the 31 from separating from each other and creating a gap.

With the shutters 30 (30A, 30B), the openings of the upper cover 16A and the lower cover 16B are always closed regardless of the movement of the track 2b. Further, the conveyance path of the printed circuit board P is also blocked by the shutter 30 (30A),
Since the screen 31 constituting the shutter 30 is made of the flexible film body as described above, the printed circuit board P can easily push the screen 31 away and pass through the shutter 30.

Next, the operation of the nitrogen-filled jet type soldering device (hereinafter abbreviated as "soldering device") 15 having the above-mentioned structure will be described.

In the operating state of the soldering device 15, the nitrogen supply device (not shown) is operated and nitrogen gas is spouted from the nitrogen supply pipes 14, 14, .... Other operations are the same as the operation of the conventional jet-type automatic soldering device. The printed circuit boards P to be soldered are sequentially transported by the transport conveyor 2, and first, a flux having a low reducing action is applied to the soldering surface (back surface) by a spray type fluxer (not shown), and then passes over the preheater. It approaches the solder bath 8 '. The printed circuit board P near the solder bath 8'is the shutter 30A.
And enters the shield 19 in a nitrogen atmosphere, and is soldered in the solder bath 8 '. At this time, as shown in FIG. 7, when the printed circuit board P to be soldered reaches the upper part of the solder bath 8 ′, it is sandwiched between the printed circuit board P and the molten solder M on the lower surface side of the printed circuit board P. An extremely narrow space C is formed. By the way, nitrogen supply pipes 14, 14, ... Are provided below the transfer line L for the printed circuit board P on the upper surface of the solder bath 8 '.
Therefore, the space C becomes a nitrogen atmosphere in which the oxygen concentration is close to 0 (zero) and the nitrogen gas concentration is extremely high even with a small amount of nitrogen gas. As a result, it is possible to effectively prevent oxidation of terminals, copper foils, etc. on the printed circuit board P, use flux with a low reducing action, and eliminate the flux cleaning step.

In addition, since the nitrogen supply pipe 14 is provided at least on the front side of each of the nozzles 11 and 12 as described above, the space C portion having the high nitrogen concentration as described above is surely provided on the front side of the nozzles 11 and 12. As a result, the soldering is performed in a nitrogen atmosphere having an extremely high concentration.

Further, in this embodiment, a shield space is formed by the shield 19 above the solder bath 8 ', and the inside of this shield space is also filled with the nitrogen gas from the nitrogen supply pipe 14. As a result, a nitrogen atmosphere having an oxygen concentration of 5% or less is created inside the shield 19 even when a nitrogen generating device utilizing membrane separation (not a nitrogen cylinder) is used as the nitrogen generating means as in the present embodiment. Therefore, it is possible to form a nitrogen atmosphere in the entire circumference of the printed circuit board P and to stabilize the nitrogen atmosphere in the space C.

In the present specification, the "nitrogen atmosphere" does not mean a nitrogen gas concentration of 100%, but means that the ratio of nitrogen is higher and the ratio of oxygen is lower than that of normal air.

The nitrogen supply pipe 14 is a solder bath 8 '.
Since it extends in the width direction of the printed circuit board P, a high concentration nitrogen atmosphere can be created for the entire width of the printed circuit board P, and even if the width of the conveyor 2 (tracks 2a, 2b) is changed, The action is not lost.

The printed circuit board P soldered by passing over the solder bath 8'passes through the shutter 30A on the outlet side in the same manner as the shutter 30A on the inlet side and goes out of the front shield 16 to the next step. Is processed.

As described above, the present invention is intended to form a particularly high-concentration nitrogen atmosphere on the upper surface of the solder bath where soldering is actually performed. There is no limitation on forming a high-concentration nitrogen atmosphere in other portions. Therefore, the shielding space as described above may be formed so as to make the wide space above the solder bath 8 ′ a nitrogen atmosphere, and in order to increase the nitrogen concentration of the shielding space in the shielding space, A nitrogen supply port different from the nitrogen supply pipe 14 may be provided.

[0037]

As described above, according to the nitrogen-filled jet type soldering device according to the first aspect, the lower surface side of the article to be soldered is provided between the article to be soldered and the molten solder surface in the solder bath. An extremely narrow space is formed, and this space is filled with nitrogen gas, so this space can be made a nitrogen atmosphere with an extremely high nitrogen gas concentration, which allows terminals and copper foils related to soldered products. It becomes possible to use a flux having a low reducing action by preventing the oxidation of the above, and to eliminate the flux cleaning step. Further, since the space formed on the lower surface of the article to be soldered is extremely small, the required nitrogen atmosphere can be formed with a small amount of nitrogen gas, and the consumption of nitrogen gas is also small.
In addition, the nitrogen supply section is located below the transfer line and the solder nozzle
It is installed in front of and extends in the direction orthogonal to the transport line.
Therefore, on the front side of the nozzle, that is, directly after soldering
Equalize the high-concentration nitrogen atmosphere to the soldered part in front
Flakes that can be reliably formed and have a small reducing action.
Soldering can be done securely even when using
And the width of the conveyor is changed, ie
Even if the width of the product to be soldered is changed, the above operation can be confirmed.
It has an excellent effect that it can be maintained .

According to the nitrogen-filled jet type soldering device of the second aspect, the soldering device of the first aspect is
Simple structure without any modification to existing solder bath
It can be realized.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a solder bath section of a nitrogen-filled jet-type soldering apparatus according to an embodiment of the present invention.

FIG. 2 is a front side view of FIG.

FIG. 3 is a plan view showing a lower cover of the shield according to the present embodiment.

FIG. 4 is a side view of the lower cover shown in FIG.

FIG. 5 is a front view showing an embodiment of a shutter that constitutes the shield according to the present embodiment together with a conveyor and the like.

FIG. 6 is a perspective view showing the shutter shown in FIG.

FIG. 7 is a partial side sectional view for explaining the operation of the present invention, showing the upper part of the solder bath together with the product to be soldered.

FIG. 8 is a perspective view showing an example of a jet type soldering device.

[Explanation of symbols]

 2 Transport Conveyor 8'Solder Tank 11 First Nozzle 12 Second Nozzle 14 Nitrogen Supply Pipe (Nitrogen Supply Section) 15 Nitrogen Filled Jet Soldering Device P Printed Circuit Board (Soldered Product) L Transfer Line

Claims (2)

(57) [Claims] 1. A conveyor for conveying an article to be soldered, and a molten solder provided under the conveyor for melting molten solder.
And a solder bath provided with a nozzle for spraying the solder into the solder bath, and at least the solder filling device in the solder bath is configured to perform soldering in a nitrogen atmosphere in a nitrogen filled jet type soldering apparatus. There is a nitrogen supply unit for supplying a nitrogen gas in the vicinity of the solder tank, at least above the solder tank and below the transfer line of the soldered article that is transferred by the transfer conveyor , and At least for the nozzle
It should be installed at the front side of the transfer conveyor in the transfer direction.
And the width which is orthogonal to the transfer direction of the transfer conveyor
A nitrogen-filled jet-type soldering device, which is characterized by extending in the same direction . 2. The nitrogen supply unit is provided in the transfer conveyor.
Provided in the width direction orthogonal to the transport direction, nitrogen gas is
2. A jetting hole is formed in the wall of the conduit to be guided.
The nitrogen-filled jet-type soldering device.