JP2548985B2 - Reflow soldering method and device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow soldering method and apparatus, and more particularly to all soldering for loading a substrate, preheating the substrate, soldering, cooling the substrate and unloading the substrate. By carrying out the attaching process in an inert gas chamber that is shielded from the outside atmosphere, solder oxidation is prevented and soldering performance is improved, and the reliability of the electrical characteristics of the completed board to which electronic components are soldered is increased, , A reflow soldering method capable of producing a finished substrate that can be used for control of advanced machines such as rockets and medical devices that directly relate to human life, or for devices that require ultra-high reliability such as computers, and Regarding the device.

2. Description of the Related Art Reflow soldering equipment applies paste cream solder to soldering points where electronic components are mounted on a substrate such as a polymer substrate, conveys the substrate by a conveyor, preheats it with a preheater, and gradually heats it. Is a device for soldering electronic parts to conductive circuits on a board by heating the solder paste to a soldering temperature (about 230 ° or more) in a short time at the final stage to melt the cream solder.

In the conventional reflow soldering apparatus, the mainstream is to irradiate infrared rays radiated from a heater directly to a board on which electronic components are mounted in the air to heat the board, and the temperature of the board regulates the transfer speed of the board. Therefore, it is very difficult to control the temperature of the substrate within a desired temperature range. In order to improve the drawbacks of such a heating method, the applicant of the present application has developed a reflow soldering method and apparatus that employs a heated air circulation method in which heated air is circulated for soldering and applied for a patent ( Japanese Patent Application Nos. 62-12071 and 62-115456) both heat the substrate to a high temperature (for example, 230 ° C.) in the air both in the present invention and in the conventional method of heating a substrate by infrared rays emitted from a heater. Since the solder is melted, oxygen in the air acts on the melted solder and the lead wires of electronic parts to oxidize them, and sufficient soldering performance cannot be obtained, and there is room for improvement.

Further, Japanese Patent Laid-Open No. Sho 63-180368 discloses a reflow soldering method and apparatus, but in the conventional example, only natural air is used as a technique for performing reflow soldering only with hot air and a gas for soldering. However, it merely discloses a technique of performing reflow soldering using nitrogen gas. Therefore, there is no disclosure of a technique for cooling a substrate with a cooled inert gas, and it has been considered that the substrate may be cooled by external air at the technical level of the conventional example. Therefore, there is a drawback that the solder or the like may be oxidized during cooling.

Further, Japanese Patent Application Laid-Open No. 64-71571 (Japanese Patent Application Laid-Open No. 1-71571) discloses a reflow furnace, but the conventional example uses only radiant heat from an infrared heater and hot air from a gas blowing heater. However, it does not disclose the soldering technique in an inert gas as in the present invention. Moreover, the technology for cooling the substrate by cooling the inert gas is not disclosed or suggested at all, and it is a different invention from the present invention in that the object, the structure and the effect are completely different.

Further, Japanese Patent Laid-Open No. 63-84767 discloses a reflow furnace, but in the conventional example, there is a total of two conveyors, one for the preheating and one for the main heating, which is only one conventionally. It is provided so that the speed can be set independently, and a discharge conveyor for a falling object, a discharge passage, shutters respectively provided at the entrances and exits of the discharge passage as disclosed in the present invention (claim 6) are completely disclosed. I haven't. The invention of the present application prevents air from entering even from a discharge conveyor or a passage of such a falling object,
The inert gas atmosphere is valued, and such a technical idea does not exist in the conventional example at all.

In addition, Japanese Utility Model Application Laid-Open No. 59-158361 discloses a solder melting apparatus for printed wiring boards. In the conventional example, however, a device for preventing floating suspended matter in the air above a conveyor for transporting the boards is prevented. The present invention (claim 6) is completely unrelated to the present invention (Claim 6), which is provided with a drip tray and does not disclose a conveyor for discharging falling objects such as substrates from the conveyor and its discharge passage. In addition, in order to prevent reflow soldering in an inert gas and to prevent the concentration of inert gas in the atmosphere from decreasing, shutters are also installed at the entrances and exits of such a passage for discharging fallen objects to prevent the inflow of external air. No technology is disclosed to prevent it. Therefore, the conventional example is completely different from the present invention in its purpose, configuration and operational effect.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the prior art, and an object of the present invention is to heat an inert gas in a gas chamber filled with the inert gas so as to heat the substrate. After heating the board to the soldering temperature and soldering, the cooled inert gas is brought into contact with the board and cooled to perform the entire soldering process in the inert gas. It is to completely prevent the oxidation of the lead wires of electronic parts. It is also intended to improve soldering performance and reliability of the finished substrate.

Another object is to arrange an inert gas tank having a large capacity in the loading and unloading parts of the substrate to keep the internal pressure at least equal to or higher than the atmospheric pressure, and to form an opening having a small area. By carrying in and carrying out from the opening through the substrate, it is possible to minimize mixing of external air into the inert gas. Still another object is to configure a transfer device for transferring a board as three conveyors of a board carry-in conveyor, a main conveyor and a board carry-out conveyor to reduce the area of the board carry-in and carry-out exits, and between the conveyors. By delivering the substrate in the inert gas tank, the inflow of air is prevented, and the air is prevented from adhering to the conveyor and being conveyed to the heating chamber of the soldering device. Still another object is to prevent the inflow of air into the gas chamber at the time of discharging the fallen object by disposing shutters on the gas chamber side and the outside of the discharge passage for discharging the fallen object from the conveying device. That is.

Still another object is to provide a preload chamber filled with an inert gas on the outside of the through hole of a device arranged to penetrate the wall of the inert gas chamber, such as a rotating shaft of a blower for circulating the inert gas. The formation is to prevent air from flowing in through the gap between the through hole and the rotary shaft. The inside of the soldering equipment is filled with approximately 100% of inert gas, and the soldering part of the substrate heated, the lead wires of electronic parts and the contact between the solder and oxygen (air) are eliminated to prevent oxidation and increase the temperature. It is to manufacture a board that can be used for important equipment by performing high performance soldering and increasing the reliability of the completed board.

In summary, the method of the present invention (Claim 1) is configured such that, in an inert gas chamber filled with an inert gas, an air blower disposed below a carrier device that conveys a substrate on which electronic components are mounted above the carrier device. The inert gas is circulated downward from the heater, the inert gas is caused to flow into a heater to be heated, the heated inert gas is brought into contact with the substrate, and then the heating is discharged from the blower. After the electronic component is soldered to the substrate by circulating an inert gas from the lower side to the upper side, the inert gas cooled by a cooling device is circulated by a pressure feeding device disposed below the transfer device to circulate the substrate. The substrate is cooled by bringing it into contact with the substrate.

Further, the device of the present invention (claim 2) is a transfer device for transferring a substrate on which electronic components are mounted, a heater arranged above the transfer device for heating the surrounding inert gas, and sucking the inert gas. And a blower for discharging and circulating, a descending circulation passage for flowing the inert gas sucked by the blower into the heater to heat and contact the substrate, and the inert gas discharged from the blower. A circulation passage formed by communicating an ascending circulation passage that raises the gas and returns the gas above the heater, a cooling device that cools the inert gas to a predetermined temperature, and sucks the inert gas cooled by the cooling device. In addition, the pressure-feeding device for contacting and cooling the substrate after the soldering process, the transfer device, the heater, the blower, the circulation passage, the cooling device, and the pressure-feeding device are housed inside the device. It is characterized in that a inert gas chamber was filled with sexual gas.

The device of the present invention (claim 6) includes a blower, a circulation passage for circulating an inert gas by the blower, a heater arranged in the circulation passage for heating while flowing the inert gas, and an electronic device. In a reflow soldering device including a transfer device that transfers a substrate on which components are mounted, the blower, the circulation passage, the heater, and the transfer device are housed inside to carry in and carry out the substrate. The discharge conveyor is provided at one end side of a discharge conveyor that fills an inert gas chamber that forms a carry-out port with an inert gas, and conveys a falling object that falls from the conveyance device that is disposed below the conveyance device in the gas chamber. A discharge passage for discharging the fallen object conveyed by the discharge chamber from the inert gas chamber, and the discharge passage is provided on the inside of the inert gas chamber and on the outside of the discharge passage in contact with the atmosphere. It is characterized in that a shutter.

The device of the present invention (Claim 7) includes a blower, a circulation passage for circulating an inert gas by the blower, a heater disposed in the circulation passage for heating while flowing the inert gas, and an electronic device. In a reflow soldering device including a transfer device that transfers a substrate on which components are mounted, the blower, the circulation passage, the heater, and the transfer device are housed inside to carry in and carry out the substrate. In addition to filling the inert gas chamber forming the carry-out port with the inert gas, the rotary shaft of the blower is provided with a preload chamber outside the casing of the inert gas chamber of the through hole penetrating the inert gas chamber. It is characterized in that an inert gas is pressure-fed to the preload chamber to maintain the pressure in the preload chamber at a pressure equal to or higher than the atmospheric pressure.

Hereinafter, the present invention will be described based on embodiments shown in the drawings. A reflow soldering device 1 according to the present invention is shown in FIG. 1 in which a carrying device 2, a heater 3, a blower 4, and a circulation passage 5 are provided.
A cooling device 6, a pumping device 8, an inert gas chamber 9,
A discharge conveyor 10 and a discharge passage 11 are provided. Referring to FIG. 1, the carrier device 2 includes a substrate 13 on which an electronic component 12 is mounted.
The substrate loading conveyor 1 is for loading and transporting
4. It is composed of a main conveyor 15 and a board unloading conveyor 16. The board carry-in conveyor 14 carries in the board 13 inserted into the carry-in port 18a formed in the main body cover 18 of the reflow soldering apparatus 1, carries it into the first inert gas tank 19, and receives it by the main conveyor 15. It is a known chain conveyor 21 that is wound around a plurality of guide rollers 20, and in order to keep the chain conveyor in a state where it is always tensioned with an appropriate tension, an idle to which elastic force of a spring 22 is applied. Rollers 23 are arranged so as to stretch the chain conveyor 21 outward. The first power transmission roller 24 is the main conveyor 15
The guide roller 25 and the guide roller 20 of the board carry-in conveyor 14 are engaged with each other, and the rotational movement of the guide roller 25 is transmitted to the guide roller 20 to move the chain conveyor 21 to convey the board 13 in the direction of arrow A. Is configured. The guide roller 20 arranged at the carry-in port 18a is formed as a roller having a small outer diameter in order to reduce the opening area of the carry-in port.

The main conveyor 15 receives the board 13 carried in by the board carry-in conveyor 14 in the first inert gas tank 19, and preheats the chamber 26, the soldering room 28, the cooling room 29 and the second inert gas tank 30. A chain conveyor 31 is wound around a guide roller 25, and one of the guide rollers is connected to a pulley 33 fixed to a rotation shaft 32a of a motor 32. The belt 34 is wound around and configured to transmit the rotation of the motor 32 to the chain conveyor 31 and travel in the direction of arrow A.

The substrate carry-out conveyer 16 is for receiving the substrate 13 from the main conveyer 15 in the second inert gas tank 30 and carrying it out in the direction of arrow A from the carry-out port 18b, and like the substrate carry-in conveyer 14, is a chain. Conveyor 35 is a guide roller
It is wound around 36, and the second power transmission roller 37
Is engaged with the guide rollers 25 and 36 to transmit power from the main conveyor 15 so that the chain conveyor 36 travels in the direction of arrow A. In addition, carry-out port 18b
The outer diameter of the guide roller 36 disposed in the guide roller 36 is designed to be as small as possible to reduce the opening area of the carry-out port 18b.

Referring also to FIG. 3, the heater 3 heats while flowing nitrogen gas, which is an example of an inert gas, and the electric heaters 38 arranged at predetermined intervals are made of metal having good thermal conductivity. , Sandwiching a sandwich structure with a metal plate 39 made of, for example, aluminum from above and below, the metal plate 39 is provided with a large number of holes 39a through which nitrogen gas flows in the plate thickness direction for heat exchange. There is. The electric heater 38 is electrically connected to an external power source (not shown) to supply electric power. A temperature sensor is provided below the heater 3.
40 is installed in the approximate center of the descending circulation passage 5D and is connected to a computer (not shown).

The blower 4 is, for example, a centrifugal blower such as a sirocco fan, as shown in FIGS. 1, 3, and 4, and is provided in the preheating chamber 26 and the soldering chamber 28, respectively. The blower is formed by fixing a plurality of blades 4a to an upper donut-shaped disc 4b and a lower disc 4c, and the disc 4c is fixed to an upper end 41a of a rotating shaft 41, and the rotating shaft 41 Is the casing 42 of the inert gas chamber 9 and the casing 43 of the preload chamber 43 closely attached to the outside of the casing so that there is no gap.
It is rotatably supported by a pair of bearings 44 and 45 fixed to a respectively. A V-belt 48 is wound around a pulley 46 fixed to the lower end 41b of the rotary shaft 41, and the V-belt is wound around a pulley 50 fixed to a rotary shaft 49a of an electric motor 49 for driving the blower 4. ing. A nipple 43b is fixed to the side surface of the casing 43a of the preload chamber 43, and is configured to pump nitrogen gas into the preload chamber 43 through a hole 43c formed in the nipple.

The circulation passage 5 has a descending circulation passage 5D in which the nitrogen gas sucked by the blower 4 flows into the heater 3 and is heated to come into contact with the substrate 13, and the nitrogen gas discharged from the blower 4 rises above the heater 3. The upward circulation passage 5U for returning is formed so as to communicate with each other, and similarly, in the preheating chamber 26 and the soldering chamber 28, the casing 42 and the inner casing are similarly provided in the left and right directions with respect to the transfer direction of the substrate 13 (direction of arrow A). An ascending circulation passage 5U is formed between it and 51.

The cooling device 6 and the pressure feeding device 8 are for cooling the substrate 13 to room temperature by bringing the cooled nitrogen gas into contact with the high-temperature (for example, 230 ° C.) substrate 13 after the soldering is completed. A nozzle chamber disposed above the transport device 2 by sucking the nitrogen gas therein into the cooling device 6 to cool it, sucking the nitrogen gas into the suction port 8a of the pressure feeding device 8 and sending it out from the sending port 8b.
It is configured so as to be pressure-fed to 52 and jetted from a large number of nozzles 52a in the direction of arrow G to come into contact with the substrate 13 to be cooled and circulated.

The discharge conveyor 10 is the transfer device 2 or the substrate in the preheating step and the soldering step in FIGS. 1 and 5.
A fall object 56 that falls from 13 is carried out to the outside. For example, an endless mesh chain 53 is wound around a guide roller 54, and a motor (not shown) conveys the conveyance device 2 in the conveyance direction (direction of arrow A). And in the opposite direction (direction of arrow B). The discharge passage 11 is a discharge port for discharging a fallen object 56 conveyed by the discharge conveyor 10 to the outside of the reflow soldering apparatus 1, and a cylindrical passage 55 disposed at one end of the discharge conveyor 10 and the cylinder. Sets of shutters 55c, 55 arranged on the inlet side 55a and the outlet side 55b of the passageway
A guide plate 58 for dropping the fallen object 56 conveyed by the d and the discharge conveyor 10 while guiding it to the inlet 55a of the tubular passage 55.
It consists of and. In addition, a sensor for detecting the presence or absence of a falling object 56, for example, an optical sensor 59 including a pair of a light emitting element 59a and a light receiving element 59b is installed immediately before the entrance 55a of the tubular passage 55. When the object 56 is detected by the sensor, the shutters 55c and 55d are sequentially opened, the falling object 56 is discharged to the outside, and then closed until a falling object 56 is detected again by a control device (not shown) so as not to allow air to flow in. It is controlled.

And, all of these conveying device 2, heater 3, blower 4, circulation passage 5, cooling device 6, pressure feeding device 8, discharge conveyor 10 and discharge passage 11 are surrounded by a casing 42, and the inside of the casing 42 is filled with nitrogen. It is formed as an inert gas chamber 9 filled with gas. The oxygen concentration in the inert gas chamber is suppressed to 100 to 1000 PPM or less by the various measures described above, and is configured not to oxidize solder or the like.

Further, an ultraviolet lamp 60 for curing the ultraviolet curable adhesive applied to the substrate 13 is provided in front of the preheating chamber 26 in the conveying direction, and a gas or the like generated in a soldering process is further provided above the main body cover 18. An exhaust fan 61 for exhausting air is provided.

Then, the method of the present invention (claim 1) is carried out by the blower 4 arranged below the carrying device 2 carrying the substrate 13 on which the electronic component 12 is mounted in the inert gas chamber 9 filled with the inert gas. The inert gas is circulated from the upper side to the lower side of the device 2, the inert gas is caused to flow into the heater 3 for heating, the heated inert gas is brought into contact with the substrate 13, and then discharged from the blower 4. By circulating the heated inert gas from the lower side to the upper side, the electronic component 12 is soldered to the substrate 13, and then the inert gas cooled by the cooling device 6 is circulated by the pressure feeding device 8 arranged below the transport device 2. In this method, the substrate 13 is cooled by bringing it into contact with the substrate 13.

The present invention is configured as described above, and its operation will be described below. First, referring to FIG. 3, the soldering chamber
The operation of 28 will be described. When the motor 49 rotates, the V-belt 4 passes through the rotation shaft 49a and the pulley 50.
8 drives the pulley 46, whereby the rotating shaft 41 rotates in one direction, and each blade 4a of the blower 4 rotates at a high speed. Then, since the negative pressure is generated in the descending circulation passage 5D, the nitrogen gas above the soldering chamber 28 flows into the hole 39a of the metal plate 39 in the direction of the arrow C and exchanges heat with the metal plate 39 heated by the heater 3 to heat it. After that, it further descends to come into contact with the substrate 13 transported by the transport device 2, and the substrate and the mounted electronic component 12
To heat. Then, the nitrogen gas that has passed through the discharge conveyor 10 is sucked by the blower 4 and flows to the left and right in the direction of arrow D, rises in the ascending circulation passage 5U as indicated by arrow E, and returns to above the heater 3. At this time, the temperature of the nitrogen gas heated by the heater 3 is detected by the temperature sensor 40, and the detection result is sent to the computer, and the computer always supplies the electric heater 38 with the nitrogen gas at a predetermined temperature. Adjust the power supply so that the temperature of the nitrogen gas in the soldering chamber 28 is
It is kept at 230 ℃.

Further, the above-mentioned operation is performed by the three preheating chambers 26 shown in FIG.
The same applies to the inside, and since the temperature of the nitrogen gas in the preheating chamber 26 is maintained at about 150 ° C., only the electric power supplied to the heater 3 is different, and therefore the description is omitted.

Next, each step of reflow soldering will be described with reference to FIG. When the substrate 13 is inserted in the direction of arrow A from the carry-in port 18a having a small opening area, the substrate carry-in conveyor 14 conveys the substrate into the first inert gas tank 19. And board 13
Is an ultraviolet ray applied to the substrate 13 when it is transferred from the substrate carry-in conveyer 14 to the main conveyer 15 in the first inert gas tank 19 and further conveyed in the direction of arrow A to pass under the ultraviolet lamp 60. After curing the curable adhesive, the preheating chamber 26
Transported to On the other hand, the board carry-in conveyor 14 which has passed the board 13 to the main conveyor 15 is guided by the guide rollers 20 and reverses its moving direction to return to the original position, so that it is attached to the gap of the chain conveyor 21 and carried in. Mouth 18
External air (oxygen) that has entered the reflow soldering apparatus 1 from a does not enter the inside from the first inert gas tank 19, and the opening area of the carry-in port 18a is formed to be small. The amount of oxygen released into the inert gas tank 19 is also extremely small.

The substrate 13 carried into the preheating chamber 26 is substantially the same as described above.
Although it is heated to 150 ° C. and is brought into contact with the circulating nitrogen gas to be heated, since the circulating nitrogen gas has a flow rate of about 3 m / sec, it is fixed to the substrate 13 with a small force by cream solder. The electronic parts 12 that are
Further, since it is heated by the heated nitrogen gas, it is not heated above the temperature of the nitrogen gas, and the substrate is gradually heated.
13 is heated uniformly. In this case, since the preheating chambers 26 are formed independently of each other, the temperature can be adjusted for each preheating chamber 26, and each preheating chamber 26 is set to a different temperature to gradually heat the substrate. Preheating is completed by finally heating the substrate 13 to about 150 ° C. while preventing the heat shock from affecting the substrate 13 and the electronic component 12.

The substrate 13 is then transported to the soldering chamber 28, where
The cream solder is heated by coming into contact with nitrogen gas heated to 230 ° C., and the electronic component 12 is soldered to the substrate 13. In the preheating chamber 26 and the soldering chamber 28, the substrate 13 and the electronic component 12 are heated as described above, and the metal portion is combined with the surrounding oxygen to be easily oxidized. Is filled with inert nitrogen gas, and the oxygen concentration is only about 100 to 1000 PPM, so ideal soldering can be performed without melting solder and lead wires of electronic parts 12 being oxidized. Be seen.

The prognosis heating chamber 26 and the soldering chamber 28 are surrounded by a casing 42 and are shielded from the external air. However, referring also to FIG. 4, the rotary shaft 41 of the blower 4 is provided so as to penetrate the casing 42, In order to prevent the inflow of external air from the gap 42a between the rotary shaft and the casing 42, compressed nitrogen gas is pressure-fed in the direction of arrow F from the nipple 43b into the preload chamber 43 so that the pressure in the preload chamber 43 is higher than atmospheric pressure. Since the air flows out from the gaps 42a and 43d, the external air does not flow into the preheating chamber 26 and the soldering chamber 28.

The substrate 13 which is still in a high temperature state after being soldered is discharged from the soldering chamber 28 by the main conveyor 15 and the nitrogen gas cooled by the cooling device 6 is jetted downward (direction of arrow G).
While being passed under the nozzle 52a and being cooled, it is conveyed to the second inert gas tank 30. The board 13 is again transferred from the main conveyor 15 to the board carry-out conveyor 16 and carried out from a carry-out port 18b having a small opening area, and soldering is completed.

On the other hand, referring also to FIG. 5, when the substrate 13 is heated and soldered in the preheating chamber 26 and the soldering chamber 28, the falling object 56 that falls from the main conveyor 15 (direction of arrow K in FIG. 3) is The sheet is placed on the mesh conveyor 53 of the discharge conveyor 10 and conveyed in the direction of arrow B, falls on the guide plate 58, and slides down on the guide plate in the direction of arrow H. When the falling object 56 crosses the sensor 59, the presence of the falling object 56 is detected, and a driving device (not shown) rotates the shutter 55c on the inlet 55a side of the tubular passage 55 in the direction of arrow I to open the falling object 56. After passing the object, the shutter 55c is rotated again in the direction of the arrow J to close the shutter 55d, and the shutter 55d on the outlet 55b side is also rotated in the direction of the arrow I to open, and the falling object 56 is discharged from the inert gas chamber 9. To rotate in the direction of arrow J to close the shutter 55d again. In this way, the falling air 56 is discharged without the outside air coming into direct contact with the nitrogen gas in the inert gas chamber 9.

As described above, the loading of the substrate 13, the preheating, the soldering, the cooling, the unloading, and the discharge of the fallen object 56 are all performed in the inert gas chamber filled with nitrogen gas while being shielded from the external air. 18 which is the contact point between the outside and the outside
a, carry-out port 18b, through gap 42a of casing 42 of rotating shaft 41
As described above, the discharge passage 11 and the discharge passage 11 are provided with measures to prevent the mixing of the external air into the nitrogen gas, and the soldering is performed while the nitrogen gas concentration in the inert gas chamber 9 is maintained at a high level. Therefore, even if the solder, the lead wire, and the like are heated to a high temperature, they are not oxidized, and ideal solder performance can be obtained.

In addition, since the nitrogen gas does not almost flow out from the closed inert gas chamber 9 and only circulates, the thermal efficiency is very good, and a small amount of nitrogen gas is sufficient for supplementing the economy. Target.

Effects The present invention, after heating the inert gas in the gas chamber filled with the inert gas to bring it into contact with the substrate and heating the substrate to the soldering temperature for soldering,
Since the entire soldering process is performed in the inert gas by bringing the cooled inert gas into contact with the substrate to cool it, there is an effect that the solder and the lead wire of the electronic component can be prevented from being oxidized. There is an effect that the soldering performance can be improved and the reliability of the completed substrate can be improved. Further, an inert gas tank having a large capacity is provided at the loading and unloading portions of the substrate to keep the internal pressure at least equal to or higher than the atmospheric pressure, and an opening portion having a small area is formed to remove the substrate from the opening portion. Since it is carried in and out, there is an effect that the mixing of air into the inert gas can be minimized. Furthermore, the transfer device is composed of three conveyors, a substrate carry-in conveyor, a main conveyor, and a substrate carry-out conveyor, to reduce the area of the substrate carry-in and carry-out ports and to transfer the boards between the respective conveyors with an inert gas tank. Since it is performed in the inside, there is an effect that the inflow of air can be prevented and the air adhering to the conveyor can be prevented from being conveyed to the heating chamber of the soldering device. Further, since the shutters are arranged on the gas chamber side and the outside of the discharge passage for discharging the fallen objects from the transfer device to open and close sequentially, the inflow of air into the gas chamber at the time of discharging the fallen objects is prevented. There is an effect that can be prevented.
Further, since the preload chamber filled with the inert gas is formed outside the through hole of the equipment arranged to penetrate the wall of the gas chamber, such as the rotating shaft of the blower for circulating the inert gas, There is an effect that air can be prevented from flowing in through the gap with the rotating shaft. Then, as described above, various devices for preventing external air from flowing into the inert gas chamber are provided at the contact portion with the outside of the inert gas chamber, and the inside of the soldering device is filled with approximately 100% inert gas. The soldered part of the board which is filled and heated with
Since the contact between the lead wire of the electronic component and the solder and oxygen has been eliminated, there is an effect that the oxidation of the metal part can be prevented and high-performance soldering can be performed, and the reliability of the completed substrate can be dramatically improved. .

[Brief description of drawings]

1 is a vertical sectional view of a reflow soldering device, FIG. 2 is a left side view of the same, and FIG. 3 is a vertical sectional view taken along the line III-III of FIG. FIG. 4 is an enlarged vertical sectional view of a main part of the blower, and FIG. 5 is an enlarged vertical sectional view of a discharge passage. 1 is a reflow soldering device, 2 is a transfer device, 3 is a heater, 4 is a blower, 5 is a circulation passage, 5U is an ascending circulation passage, and 5D.
Is a descending circulation passage, 6 is a cooling device, 8 is a pressure feeding device, 9 is an inert gas chamber, 10 is a discharge conveyor, 11 is a discharge passage, 12 is an electronic component, 13 is a substrate, 14 is a substrate carry-in conveyor, and 15 is a main A conveyor, 16 is a substrate unloading conveyor, 18a is a carry-in port, 18b is a carry-out port, 19 is a first inert gas tank, 20 is a guide roller, 24 is a transfer roller, 25 is a guide roller, 26 is a preheating chamber, 28 Is a soldering chamber, 29 is a cooling chamber, 30 is a second inert gas tank, 32
Is a drive motor, 36 is a guide roller, 37 is a transmission roller, 41
Is a rotating shaft, 42 is a casing, 43 is a preload chamber, 55c and 55d are shutters, and 56 is a falling object.

Claims (9)

(57) [Claims] 1. An inactive gas chamber filled with an inert gas, wherein a blower disposed below a transfer device for transferring a substrate on which an electronic component is mounted is used to move the inert gas downward from above the transfer device. The gas is circulated, the inert gas is caused to flow into the heater for heating, the heated inert gas is brought into contact with the substrate, and then the heated inert gas discharged from the blower is moved upward from below. After the electronic components are soldered to the substrate by circulating, the inert gas cooled by the cooling device is circulated by the pressure feeding device arranged below the transport device to contact the substrate to cool the substrate. A reflow soldering method characterized by: 2. A transfer device for transferring a substrate on which electronic components are mounted, a heater arranged above the transfer device for heating an inert gas in the surroundings, and a suction and discharge of the inert gas for circulation. A blower for causing the inert gas sucked by the blower to flow into the heater to heat the heater to contact the substrate and raise the inert gas discharged from the blower to raise the inert gas. A circulation passage formed by communicating an ascending circulation passage that returns to above the heater, a cooling device that cools the inert gas to a predetermined temperature, and suction of the inert gas cooled by the cooling device to end the soldering process The pressure feeding device for contacting and cooling the substrate, the transfer device, the heater, the blower, the circulation passage, the cooling device, and the pressure feeding device are housed therein to fill the inert gas. Reflow soldering apparatus comprising the inert gas chamber. 3. An internal pressure is provided by forming an opening portion having a small area for allowing the substrate transported by the transport device to pass through at each of the substrate loading and unloading portions of the inert gas chamber. The reflow soldering device according to claim 2, further comprising an inert gas tank having a large capacity, which is set to a pressure equal to or higher than an atmospheric pressure outside the reflow soldering device. 4. The transfer device comprises a substrate carry-in conveyor in which a guide roller near the carry-in entrance has a small outer diameter in order to reduce an opening area of the carry-in entrance, and a carry-in conveyor. A pre-heating chamber for receiving the pre-heated substrate and pre-heating the pre-heated substrate; a soldering chamber for further heating the pre-heated substrate to melt solder to solder the electronic component to the substrate; A main conveyor that sequentially conveys the cooled inert gas to a cooling chamber where the inert gas is brought into contact, and the board carry-out port that receives the soldered board from the main conveyor and carries the board out from the board carry-out port 2. The substrate unloading conveyor according to claim 2, wherein the guide roller is formed to have a small outer diameter to reduce the opening area of the carry-out port.
The reflow soldering device described in 1. 5. The transport device comprises an electric motor for rotating and driving a drive roller of the main conveyor, and two motors for transmitting the movement of the main conveyor to a drive roller of the substrate carry-in conveyor and a drive roller of the substrate carry-out conveyor. A transfer roller is provided, and the delivery of the substrate from the substrate loading conveyor to the main conveyor and the delivery of the substrate from the main conveyor to the substrate unloading conveyor are performed in the inert gas tank. The reflow soldering device according to claim 4. 6. A blower, a circulation passage for circulating an inert gas by the blower, a heater arranged in the circulation passage for heating while flowing the inert gas, and a substrate on which electronic components are mounted. In a reflow soldering device having a transfer device for transferring, the blower, the circulation passage,
The heater and the transfer device are housed inside, and an inert gas chamber having an inlet for loading the substrate and an outlet for unloading the substrate is filled with an inert gas, and the inert gas is placed below the transport device in the gas chamber. A discharge passage is formed at one end of a discharge conveyor that conveys fallen objects that fall from the installed conveying device, and a discharge passage that discharges the fallen matter conveyed by the discharge conveyor from the inert gas chamber is formed. A reflow soldering device, characterized in that shutters are provided inside the active gas chamber and outside the exhaust passage in contact with the atmosphere. 7. A blower, a circulation passage for circulating an inert gas by the blower, a heater arranged in the circulation passage for heating while flowing the inert gas, and a substrate on which electronic parts are mounted. In a reflow soldering device having a transfer device for transferring, the blower, the circulation passage,
The inert gas is filled in an inert gas chamber having a carry-in port for loading the substrate and a carry-out port for loading the substrate, and the rotating shaft of the blower has the inert gas. A precompression chamber is provided outside the casing of the inert gas chamber through a through hole that penetrates the chamber, and the inert gas is pressure-fed to the precompression chamber to maintain the pressure in the precompression chamber at a pressure equal to or higher than atmospheric pressure. A reflow soldering device having the above structure. 8. The reflow soldering method according to claim 1, wherein the inert gas is nitrogen gas. 9. The reflow soldering device according to claim 2, wherein the inert gas is nitrogen gas.