JP3582989B2 - Reflow soldering equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reflow soldering apparatus for a plate-like work to be soldered such as a printed wiring board.
[0002]
[Prior art]
When soldering a plate-shaped work to be soldered, for example, a printed wiring board on which a large number of electronic components are mounted and solder is supplied in advance to the soldered portion, a reflow soldering apparatus is used.
[0003]
A reflow soldering apparatus is an apparatus that performs soldering by heating at least a portion of a printed wiring board to be soldered and melting the solder.A device using hot air as a heating means, a heat ray such as a laser beam or an infrared ray. , A device using them, and the like.
[0004]
Further, as in the technique described in the specification of Japanese Patent No. 25028226, while suppressing a temperature rise of an electronic component having a low heat-resistant temperature mounted on one surface side of a printed wiring board, the other surface side is prevented from rising. There is also a technique of a reflow soldering apparatus for performing reflow soldering by heating a portion to be soldered.
[0005]
In order to prevent oxidation of the soldered portion and the solder and to improve the fluidity of the molten solder, an inert gas such as a nitrogen gas (N ₂ gas) is supplied into the chamber so that the atmosphere in a low oxygen concentration atmosphere can be prevented. There is also a technology of an apparatus that performs reflow soldering. In such a reflow soldering apparatus, the sealing property of the chamber against the outside air is important in reducing the consumption of N ₂ gas. Therefore, the configuration is such that hot air for heating the printed wiring board or cold air for cooling is circulated in the chamber so as not to leak out of the chamber.
[0006]
This is not limited to the case where the N ₂ gas is supplied into the chamber, but is also important from the viewpoint of maintaining good thermal efficiency of the soldering apparatus. The work to be soldered in the chamber isolated from the outside air is important. This is the reason why heating or cooling is usually performed.
[0007]
On the other hand, as a means for transporting a plate-like work to be soldered, for example, a printed wiring board, a chain conveyor for transporting a printed wiring board by placing and supporting both side ends of the printed wiring board on pins of two parallel chain conveyors is used. It is commonly used as a conveyor.
[0008]
[Problems to be solved by the invention]
In a reflow soldering device that blows hot air to heat the printed wiring board and performs reflow soldering, or a reflow soldering device that cools the printed wiring board by blowing cool air, Therefore, there is a problem that heating and cooling at both ends supported by the transport conveyor become insufficient. That is, there is a problem that temperature unevenness occurs.
[0009]
FIG. 6 is a cross-sectional view showing a conventional example of a conveyer of a reflow soldering apparatus, and is a diagram for explaining a problem in a case where hot air heating or cold air cooling is performed.
[0010]
In this figure, a printed wiring board 1 has a surface-mounted component 2 mounted thereon, and both end portions 1 a of the printed wiring board 1 are supported by pins 5 of a chain 4 of a conveyor 3, and a position is determined by a guide plate 6. It is regulated and transported. This is an example of a general reflow soldering apparatus configured to blow hot or cold air from a direction perpendicular to the plate surfaces 1b and 1c of the printed wiring board 1. However, in FIG. 6, a chamber, a heating unit for generating hot air or cold air, a cooling unit, an atmosphere circulation path of an atmosphere circulation unit for circulating hot air or cold air, a blowing unit, and the like are known and are omitted. Absent. The transport direction of the transport conveyor 3 is a direction perpendicular to the paper surface of FIG.
[0011]
As shown in FIG. 6, a conveyor 3 for supporting and transporting both side edges 1a of the printed wiring board 1 is constituted by two parallel lines, and a chain guide 7 and a conveyor frame 8 for supporting a chain 4 which transports and travels. It has. As the conveyor frame 8, there are hollow members as shown in FIG. 6 and members having a U-shaped or L-shaped cross section.
[0012]
Here, as can be seen from FIG. 6, the hot or cold air blown to the printed wiring board 1 is obstructed by the conveyor frames 8 on the both end portions 1 a of the printed wiring board 1 and obstructs the conveyer frames 8. Does not flow enough. That is, the hot air or the cold air flows at a high speed at a position away from the board surfaces 1b and 1c of the printed wiring board 1 as shown by an arrow D, and is relatively slow at both side ends 1a of the printed wiring board 1 as shown by an arrow E. It only flows at speed.
[0013]
Therefore, there is a problem in that heating or cooling of the both end portions 1a of the printed wiring board 1 cannot be sufficiently performed, and temperature unevenness occurs.
[0014]
The problem is that in today's printed wiring board 1 in which the surface-mounted components 2 are mounted with high density at every corner of both end portions 1a of the printed wiring board 1, heating or cooling of the both end portions 1a is required. Since it cannot be performed sufficiently, the heating or cooling temperature profile is not uniform in each part of the printed wiring board 1, which causes a soldering failure or a component failure.
[0015]
An object of the present invention is to make hot air or cold air flow at a uniform speed along the surface of a printed wiring board. It is another object of the present invention to perform reflow soldering without causing soldering defects and component defects.
[0016]
[Means for Solving the Invention]
In the reflow soldering apparatus of the present invention, an opening is provided in the conveyor frame facing the printed wiring board , and hot air or cold air blown from a direction perpendicular to the board surface of the printed wiring board is sucked from the opening and circulated in the chamber. It is characterized by having such a configuration.
[0017]
That is, to convey the chamber and supports the both ends of the plate-shaped work to be soldered in parallel two rows conveyor of, from the atmosphere circulating means a heated atmosphere or cooling atmosphere by the heating means or cooling means In a reflow soldering apparatus which blows out and blows the work to be soldered from a direction perpendicular to the plate surface to heat or cool the work to be soldered, the reflow soldering machine of the two parallel conveyors has provided suction openings in the portion of the side facing the soldering work suck the atmosphere in the chamber, respectively, to the plate surface of the work to be soldered to connect to the inlet side of said atmosphere circulating means to both suction opening Atmosphere in which hot air or cold air blown from a right angle direction is sucked and circulated from both suction openings of the both conveyor frames. A reflow soldering device configured to form a ring passage.
[0018]
As a result, the heated atmosphere, that is, the hot air or the cooled atmosphere, which has blown at right angles to the plate-like work to be soldered, flows along the plate surface of the plate-like work to be soldered and flows from both side ends thereof. The work is sucked into the blow opening of the conveyor frame and flows, so that both side ends of the plate-like work to be soldered can be heated or cooled evenly.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention can be implemented in the following embodiments.
[0020]
[First Embodiment]
FIG. 1 is a cross-sectional view showing a first embodiment of the reflow soldering apparatus according to the present invention, and FIG. 2 is a vertical cross-sectional view showing the entire reflow soldering apparatus shown in FIG. The same parts are shown, and the N ₂ gas supply system is shown by a symbol diagram.
[0021]
In these figures, the inside of the furnace body 9 is divided into three chambers, that is, a heating section heating chamber 10, a soaking section heating chamber 11, and a reflow section heating chamber 12. A conveyor 13 is provided with two parallel chains 4 rotating in the direction.
[0022]
An atmosphere circulation path 16 is formed by a partition plate 15 above the conveyor 13 in a chamber 14 forming the furnace body 9, and is driven by the atmosphere circulation path 16 and a motor 17 provided in the atmosphere circulation path 16. An atmosphere circulating means is formed by the fan 18 to be adjusted, a flow straightening plate 19 for adjusting the flow of the atmosphere, that is, the flow of hot air, and the heater 20 for heating the circulating atmosphere. This allows the printed wiring board 1 to be heated by circulating the atmosphere heated by the heater 20 and blowing it as hot air onto the printed wiring board 1 as shown by arrow B. That is, the hot air circulation type heating means 21 is constituted. Further, an atmosphere circulation path 22 and a cooling means 24 having a cooling device 23 are provided below the conveyor 13.
[0023]
The conveyor 13 is composed of a chain 4, a chain guide 7 and a conveyor frame 25. The conveyor frame 25 on the left side of FIG. The support width can be adjusted according to the width of the plate 1. Further, the sliding plate 26 provided on the left conveyor frame 25 is provided in sliding contact with the chamber 14, so that even when the support width of the transport conveyor 13 is adjusted, the atmosphere above and below the transport conveyor 13 can be shut off. It is configured as follows.
[0024]
The chain guide 7 for guiding the running of the chain 4 is provided close to the upper end side 25a of the conveyor frame 25, so that the hot air flowing near the upper surface 1b of the printed wiring board 1 is not obstructed by the conveyor frame 25. Can flow linearly.
[0025]
The conveyor frame 25 has a tubular shape, and the inside of the tube of the conveyor frame 25 is partitioned by a partition 25b (shown by a mesh in FIG. 1) for each of the heating chambers 10, 11, and 12. A suction opening 27 is provided below the chain guide 7 so as to face the printed wiring board 1, and a hose 29 is connected via a hose connection port 28 provided in the conveyor frame 25. The atmosphere is sucked into the blower 31 connected to the lower part of the chamber 14 through the cooling device 23 through the hose 30 provided on the outside of the chamber 14, and then the cool air blown out from the blower 31 divides the inside of the chamber 14 into a rectifying plate. Atmospheric circulation means comprising cooling means 24 sprayed on the lower surface of the printed wiring board 1 through 32. Therefore, the cool air flowing near the lower plate surface 1c of the printed wiring board 1 can also flow straight to the suction opening 27 of the conveyor frame 25 without being disturbed as shown by the arrow C.
[0026]
On the other hand, a gas supply pipe 52 of the N ₂ gas supply means 40 is provided in the vicinity of the fan 18 to supply N ₂ gas into the chamber 14 to form an atmosphere having a low oxygen concentration.
[0027]
N ₂ gas on-off valve 42 from the _{N 2} gas supply device 41 such as a _{N 2} gas cylinder, filter 43, pressure control valve 44, pressure gauge 45 for pressure monitor primarily become off valve 46, flow control valve 47, flow rate The gas is supplied from the respective gas supply pipes 52 provided in the vicinity of each fan 18 into the chamber 14 via a total 48, an on-off valve 49 provided for each chamber, a flow control valve 50, and a flow meter 51. . In FIG. 1, detailed illustration of the gas supply means 40 is omitted.
[0028]
As described above, the reflow soldering apparatus heats the upper surface 1b of the printed wiring board 1 to be conveyed in an atmosphere having a low oxygen concentration and performs the reflow soldering while heating the lower surface 1c. This is a reflow soldering apparatus which realizes a soldering method for suppressing a rise in temperature of the surface while blowing cold air on the surface.
[0029]
Further, performing the reflow soldering by giving a temperature difference between the one (upper) plate surface 1b and the other (lower) plate surface 1c of the printed wiring board 1 requires one plate surface 1b side (upper side in the drawing). ) Is heated to perform reflow soldering, so that the solder on the other plate surface 1c side (the lower surface side in the drawing), which has already been soldered, is prevented from melting, or the other plate surface 1c is It is also necessary to protect the mounted electronic components having a low heat-resistant temperature. This is also described in the aforementioned Japanese Patent No. 2502826.
[0030]
1 and 2, by providing a heating device 33 in place of the cooling device 23, both the plate surfaces 1b and 1c of the printed wiring board 1 can be heated together.
[0031]
As the cooling device 23, known technologies such as natural air cooling composed of fins or the like, forced cooling using cooling water, and a heat exchanger using a heat pump can be used.
[0032]
When the cooling device 23 is used as the heating means 34 having a heating device 33 instead of the cooling device 23, it is easiest to use a sheathed heater or the like.
[0033]
Thus, by providing the suction opening 27 in the conveyor frame 25 and circulating the atmosphere through the suction opening 27, the atmosphere flowing on the surface of the printed wiring board 1 is changed over the entire board surfaces 1b and 1c of the printed wiring board 1. It is possible to flow linearly, and it is possible to heat or cool the both ends 1a of the printed wiring board 1 evenly. As a result, good soldering can be performed over the entire surface of the printed wiring board 1.
[0034]
In FIG. 2, reference numeral 35 denotes a labyrinth portion provided in the furnace body 10, and reference numeral 36 denotes a suppression plate forming the labyrinth portion 35.
[0035]
[Second embodiment]
FIG. 3 is a cross-sectional view showing a second embodiment of the present invention. FIG. 3 is a view corresponding to FIG. 1, but shows only the main parts, the heating means, the circulating means, the blowing means and the like are shown in a symbol diagram, and other chambers and the like are omitted. 1 denote the same parts.
[0036]
In FIG. 3, the inside of a conveyor frame 61 constituting the conveyor 60 is vertically partitioned by a partition plate 62, and a chain guide 7 is provided in the middle of the outside in the vertical direction. On the side and the lower side, suction openings 63 and 64 are provided facing the printed wiring board 1 respectively.
[0037]
Then, an atmosphere (hot air or cold air) blown onto the upper plate surface 1b of the printed wiring board 1 and flowing along the plate surface 1b is sucked into the upper suction opening 63 as shown by an arrow B, and the printed wiring is drawn. An atmosphere (hot air or cold air) blown onto the plate surface 1c below the plate 1 and flowing along the plate surface 1c is sucked through the lower suction opening 64 as shown by an arrow C.
[0038]
Blowers 65 and 66 are used as atmosphere circulation means, and heating devices 71 and 72 or cooling devices 73 and 74 are provided in circulation paths 69 and 70 connected to hose connection ports 67 and 68 of the conveyor frame 61. are doing.
[0039]
The operation is the same as that of the first embodiment, and hot air or cold air can be made to flow linearly over the entire board surfaces 1b and 1c of the printed wiring board 1. Heating or cooling can be performed evenly.
[0040]
[Third Embodiment]
FIG. 4 is a cross-sectional view showing a main part of the third embodiment of the present invention, showing only the vicinity of the conveyor frame, and omitting other parts. The same reference numerals as those in FIG. 1 denote the same parts, and are examples of a conveyor 80 that also serves as a conveyor frame 81 and a chain guide 7. The conveyor 80 is a chain guide in which a chain 4 runs on a tubular conveyor frame 81. A portion 82 is formed. Also in this case, the suction opening 83 is provided so that hot air or cold air can flow linearly as shown by arrows B and C over the entire board surfaces 1b and 1c of the printed wiring board 1. Further, hot air or cold air indicated by arrow C can be sucked into a blower (not shown) from the hose connection port 84 via the hose 29.
[0041]
[Fourth Embodiment]
5 (a) and 5 (b) are views showing a main part of a fourth embodiment of the present invention. FIG. 5 (a) is a cross-sectional view, and FIG. 5 (b) is FIG. 5 (a). Is a partially cutaway perspective view of FIG. 1, showing the vicinity of the conveyor frame, and other parts are not shown. In these figures, the same reference numerals as those in FIG. 1 indicate the same parts.
[0042]
5 (a) and 5 (b) also show an example of the conveyor 90 which also serves as a conveyor frame and a chain guide, but differs from FIG. 4 in that the conveyor frame 91 is not formed in a tubular shape. That is, the conveyor frame 91 is composed of an upper frame 92 and a lower frame 93, each of which is formed in a long shape. The upper frame 92 has a thin portion 92a and a thick portion 92b, and the lower frame 93 has the same thickness as the thick portion 92b of the upper frame 92. A chain guide 94 on which the chain 4 runs is formed between the thick portion 92b of the upper frame 92 and the lower frame 93. The upper frame 92 and the lower frame 93 are connected to each other by the connecting tool 95 to be integrally formed, thereby forming the conveyor frame 91.
[0043]
In addition, a plurality of suction openings 96 are formed in the lower frame 93, and a hood 97 that covers these suction openings 96 is attached. The hood 97 has a hose connection port 98 for connecting the hose 29. Reference numeral 99 denotes a screw for attaching the hood 97 to the lower conveyor frame 93.
[0044]
In FIG. 5B, a part of the conveyor frame 91 is shown to explain its shape, and the connector 95, the suction opening 96, and the hood 97 are appropriately provided at required places.
[0045]
As described above, the cool air or hot air blown from the blower 31 shown in FIG. 1 is blown to the lower surface 1c side of the printed wiring board 1 and then, as shown by the arrow C in FIG. And is collected in the hood 97 through the suction opening 96 and flows from the hose connection port 98 to the hose 29.
[0046]
Therefore, also in this case, hot air or cold air can flow linearly over the entire board surfaces 1b and 1c of the printed wiring board 1 as shown by arrows B and C.
[0047]
【The invention's effect】
As described above, according to the reflow soldering apparatus of the present invention, since the suction opening for sucking the atmosphere in the chamber into the atmosphere circulation path is provided in the portion of the conveyor frame of the conveyor that faces the work to be soldered, atmosphere blown from a direction perpendicular to the plate surface of the printed circuit board becomes possible to linearly flow across the plate surface of the print wiring board flows the surface, both side ends of the printed wiring board is also uniformly heated or Cooling can be performed. As a result, good soldering can be performed over the entire surface of the printed wiring board. In addition, the hot air and cold air in the chamber are circulated in the chamber and are not leaked out of the chamber, so that good thermal efficiency can be maintained. In addition, an inert gas is supplied to perform soldering in a low oxygen concentration atmosphere. Also in the case of performing, the consumption of the inert gas can be kept low, and the cost can be saved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing the entire reflow soldering apparatus of FIG. 1;
FIG. 3 is a cross-sectional view showing a second embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a third embodiment of the present invention.
5A and 5B are diagrams showing a main part of a fourth embodiment of the present invention, wherein FIG. 5A is a cross-sectional view, and FIG. 5B is a partially cutaway perspective view of FIG. 5A. .
FIG. 6 is a cross-sectional view showing a conventional example of a transport conveyor of a reflow soldering apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Printed wiring board 1a Side end 1b Plate surface 1c Plate surface 2 Surface-mounted component 4 Chain 5 Pin 6 Guide plate 7 Chain guide 9 Furnace 10 Heating section heating chamber 11 Temperature uniforming section heating chamber 12 Reflow section heating chamber 13 Transport Conveyor 14 Chamber 15 Partition plate 16 Atmospheric circulation path 17 Motor 18 Fan 20 Heater 21 Heating means 22 Atmospheric circulation path 23 Cooling device 24 Cooling means 25 Conveyor frame 26 Sliding plate 27 Suction opening 28 Hose connection ports 29, 30 Hose 31 Blower 33 Heating device 34 Heating device 40N ₂ gas supply device 41N ₂ gas supply device 60 Conveyor conveyor 61 Conveyor frame 62 Partition plates 63, 64 Suction openings 65, 66 Blowers 67, 68 Hose connection port 80 Conveyor 81 Conveyor frame 82 Chain guide 83 Suction opening 84 Hose connection port 90 Transfer con Bear 91 Conveyor frame 92 Upper frame 93 Lower frame 94 Chain guide 95 Connecting tool 96 Suction opening 97 Hood 98 Hose connection port

Claims (1)

The two ends of the plate-like work to be soldered are supported by two parallel conveyors, conveyed in the chamber, and the atmosphere heated or cooled by the heating means or the cooling means is blown out from the atmosphere circulation means. In a reflow soldering apparatus that sprays from a direction perpendicular to the plate surface of the work to be soldered and heats or cools the work to be soldered,
Suction openings for sucking the atmosphere in the chamber are respectively provided in portions of the two conveyor frames of the two parallel conveyors facing the work to be soldered, and these suction openings are provided on the suction side of the atmosphere circulation means. Hot air or cold air blown from a direction perpendicular to the plate surface of the work to be soldered and connected is formed in an atmosphere circulation path that sucks and circulates from both suction openings of both the conveyor frames,
A reflow soldering machine characterized by the following.

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