JP2005175286A - Heating device, reflow furnace having the same and heating method of circuit substrate, - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating device and a heating method in which the change of a furnace pressure in association with conveying of a substrate is reduced without reaching a diffusing nozzle position of an opposite side, while a diffused atmospheric gas incorporates a sufficient diffusing speed and further heating temperature difference between above and below a circuit substrate can be assured sufficiently; and to provide a reflow furnace using this device. <P>SOLUTION: The heating device for heating the circuit substrate 2 to be conveyed includes a circulation fan 8 for circulating an atmospheric gas, a heater 10 for heating the atmospheric gas, a diffusing nozzle 6 for diffusing the heated atmospheric gas to blow the heated atmospheric gas to the circuit substrate 2, and a suction port 7 for sucking the atmospheric gas. The diffusing nozzle 6 and the suction port 7 are disposed at near positions. Thus, the flow of the atmospheric gas diffused from the diffusing nozzle 6 by the sucking force of the suction port 7 is attenuated by predetermined attenuating characteristic. The heating method is provided. And, the reflow furnace using this device is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heating apparatus and a heating method for heating a circuit board on which an electronic component is mounted by blowing hot air in an atmosphere gas, and a reflow furnace for soldering a circuit board using the heating apparatus.

  Currently, SMD (Surface Mounted Device) in which various electronic components are mounted on the surface of a circuit board and soldered is widely used in electronic devices. In order to manufacture this SMD, in many cases, an electronic component is mounted on a circuit board on which cream solder is printed, and soldering is performed by heating in a reflow furnace. This reflow furnace heats the circuit board while the circuit board on which the electronic components are mounted is transported horizontally by the transport device in the furnace, thereby melting the solder and soldering the circuit board and the electronic parts. It is a heating furnace that performs. This reflow furnace is usually an atmosphere furnace, and the circuit board is heated in an atmosphere gas such as nitrogen to prevent oxidation or the like generated during soldering.

  As a circuit board heating apparatus, a heating apparatus that blows hot air on the circuit board to melt the solder is widely used. This heating device includes a circulation fan that circulates the atmospheric gas in the reflow furnace, a heater that heats the circulated atmospheric gas, and a spray nozzle that blows the heated atmospheric gas onto the circuit board. This heating device is installed above and below the circuit board and heats the upper and lower surfaces of the circuit board.

The heating method using this heating apparatus is as follows.
Atmospheric gas is circulated in the furnace by a circulation fan. And after circulating atmospheric gas is heated with a heater, it blows off from a blowing nozzle, is sprayed on a circuit board, and heats a circuit board. After that, while being sucked by the circulation fan and circulating in the furnace, it is again heated by the heater and the same cycle is repeated. By the above, the circuit board conveyed one after another can be heated.

In this heating apparatus, in order to effectively heat the circuit board, a method of blowing hot air onto the circuit board is important. For this reason, various proposals have been made for a blowout nozzle for blowing out hot air. As an example, there has been proposed a heating apparatus that blows hot air using a plurality of pipe-shaped blowing nozzles 106 as shown in FIG. (See cited document 1.)
In this case, hot air is blown onto the circuit board from a plurality of pipe-shaped blowing nozzles 106 arranged at predetermined intervals, and heating is mainly performed by forced convection heat transfer. The atmospheric gas that bounces off the circuit board 102 is circulated by the circulation fan, heated again to become hot air, and heats the circuit board 102 again. Repeat the above cycle to continue heating.
Here, desired heating can be performed by setting the circulation fan so that a predetermined blowing speed is obtained when the circuit board 102 is reached.
JP 2001-326455 A

  As described above, in the heating device using the pipe-shaped blowing nozzle 106, in order to perform sufficient heating, the circulation fan is set so that a blowing speed equal to or higher than the value that is the position of the circuit board 102 is obtained. In that case, in the case where the circuit board 102 as shown in FIG. 9B does not exist, the atmospheric gas blown from the upper blowing nozzle 106 reaches the position of the lower blowing nozzle 106. In addition, the atmospheric gas blown from the lower blowing nozzle 106 reaches the position of the upper blowing nozzle 106.

In the actual operation of the reflow furnace, the circuit board 102 is horizontally transported by the transport device, so that the circuit board 102 as shown in FIG. 8 (a) exists and the circuit board 102 shown in FIG. 8 (b). The state where the circuit board 102 does not exist is shifted alternately. In practice, the time period when the circuit board 102 does not exist is generally longer.
Therefore, the atmospheric gas circulating in the reflow furnace is rebounded to the circuit board when the circuit board is present, and flows to the blowing nozzle opposite to the blowing position when the circuit board is not present. It will be.

Therefore, the flow of the atmospheric gas circulating in the reflow furnace greatly changes depending on the presence or absence of the circuit board accompanying the conveyance of the circuit board, and the furnace pressure in the reflow furnace greatly fluctuates accordingly.
In a reflow furnace, an atmosphere gas such as nitrogen gas is filled in the furnace, and the furnace pressure is set slightly higher than the outside air to prevent the outside air from flowing into the furnace. If the furnace pressure fluctuates, it is necessary to supply a larger amount of atmospheric gas into the furnace in order to prevent outside air from flowing even when the furnace pressure is lowered. In this case, since the average furnace pressure rises, the flow rate of the non-atmospheric gas flowing out of the furnace also increases, and the consumption of the atmospheric gas further increases.
These atmospheric gases such as nitrogen are expensive and cause a problem that the running cost for operating the reflow furnace increases.

  On the other hand, if the atmospheric gas blowing speed is adjusted so that the atmospheric gas blown from the blowing nozzle does not reach the blowing nozzle position on the opposite side in order to suppress fluctuations in the furnace pressure, the circuit board position is sufficient. Since a high spraying speed cannot be obtained, there arises a problem that sufficient heating cannot be performed.

  Furthermore, in soldering using lead-free solder, which is now becoming mainstream, since the melting point thereof is high, it is necessary to heat by spraying an atmosphere gas having a temperature higher than that in the past. However, when this high-temperature hot air is blown onto an electronic device, the electronic device may be damaged by heat. Therefore, in order to prevent this damage, it is necessary to adopt a heating method in which the gas temperature blown to the upper side of the circuit board on which the electronic device is mounted is made lower than the gas temperature blown from the lower side and a temperature difference is given between the upper and lower sides of the circuit board. Came out.

  Even in this case, in the heating apparatus using the above-described blowing nozzle 102, in a state where the circuit board 102 occupying a long time zone does not exist, the relatively low-temperature atmospheric gas blown from the upper blowing nozzle 106 is The relatively high temperature atmospheric gas blown from the lower blow nozzle 106 reaches the position of the upper blow nozzle 106, so that the high temperature gas and the low temperature gas are mixed, There arises a problem that it becomes difficult to provide a desired temperature difference between the upper and lower sides.

  Therefore, the object of the present invention is to solve the above-mentioned problems so that the blown-out atmospheric gas has a sufficient blowing speed at the position of the circuit board but does not reach the blowing nozzle position on the opposite side. To reduce the fluctuation of the furnace pressure accompanying the conveyance of the circuit board, and further, a heating device and a heating method capable of sufficiently taking the temperature difference between the upper and lower heating of the circuit board, and a reflow furnace equipped with the heating device. It is to provide.

  In order to achieve the above object, a first embodiment of a circuit board heating apparatus according to the present invention is a heating apparatus for heating a circuit board conveyed by a conveying apparatus in a shell filled with atmospheric gas. A circulation fan that circulates the atmospheric gas in the shell, a heater that heats the atmospheric gas circulated by the circulation fan, a blowing nozzle that blows the atmospheric gas heated by the heater and blows it to the circuit board, and the atmospheric gas in the shell A suction port for sucking the air into the circulation fan, the blower nozzle and the suction port are arranged in close proximity, and the flow of the atmospheric gas blown from the blower nozzle by a suction force from the suction port is predetermined. It is characterized by attenuation with attenuation characteristics.

  In another embodiment of the circuit board heating apparatus of the present invention, the flow rate when the atmospheric gas blown from the blow nozzle reaches the circuit board is such that the flow velocity is ½ or less of the initial speed blown from the blow nozzle. It has the characteristics.

  In another embodiment of the circuit board heating device of the present invention, when the heating device is installed on both sides of the circuit board and both sides of the circuit board are heated, the atmospheric gas blown out from one blowing nozzle is Before reaching the blowing nozzle on the opposite side, the direction of flow is changed and the air is sucked into the suction port on the one blowing nozzle side.

  Another embodiment of the circuit board heating device of the present invention is characterized in that the blowout nozzles and the suction ports are arranged alternately.

  Another embodiment of the circuit board heating device of the present invention is characterized in that the nozzle port and the suction port of the blowout nozzle are arranged so as to be aligned in the same plane.

  Another embodiment of the circuit board heating device of the present invention is characterized in that the suction pressure from the suction port is a suction pressure of 150 Pa or less.

  Another embodiment of the circuit board heating device of the present invention is characterized in that the flow path for blowing out the atmospheric gas is arranged outside the flow path for sucking in the atmospheric gas.

  In another embodiment of the circuit board heating apparatus of the present invention, in addition to the suction port, a new suction port for sucking the atmospheric gas in the shell to the circulation fan is installed at a position not close to the blowout nozzle. It is characterized by that.

  Another embodiment of the apparatus for heating a circuit board according to the present invention is characterized in that a damper for adjusting the suction force from the suction port is further provided.

Another embodiment of the circuit board heating apparatus of the present invention is characterized in that the atmospheric gas blown from the blow nozzle is mainly sucked after passing through the circuit board to attenuate the flow.

  The first embodiment of the reflow furnace of the present invention is a reflow furnace for soldering a circuit board using the circuit board heating apparatus shown in the above embodiment.

A first embodiment of a method for heating a circuit board according to the present invention is a method in which an atmosphere gas is filled in a shell, and heating is performed while the circuit board is transported by a transport device,
A step of circulating the atmospheric gas in the shell with a circulation fan, a step of heating the atmospheric gas circulated by the circulation fan with a heater, and a step of blowing off the atmospheric gas heated by the heater using a blowing nozzle and blowing it onto the circuit board And a step of sucking the atmospheric gas in the shell to the circulation fan using the suction port, the blower nozzle and the suction port are arranged in close proximity, and blown out of the blower nozzle by the suction force from the suction port. The flow of the atmospheric gas is attenuated with a predetermined attenuation characteristic.

  In another embodiment of the method for heating a circuit board according to the present invention, the flow rate when the atmospheric gas blown from the blowing nozzle reaches the circuit board flows so as to be 1/2 or less of the initial speed blown from the blowing nozzle. Is characterized by attenuating.

  In another embodiment of the method for heating a circuit board according to the present invention, when both surfaces of the circuit board are heated, before the atmosphere gas blown out from one blowing nozzle reaches the blowing nozzle on the opposite side, the flow direction And the flow is attenuated so as to be sucked into the suction port on the one blow-out nozzle side.

  Another embodiment of the method for heating a circuit board according to the present invention is characterized in that atmospheric gas is sucked from the suction port at a suction pressure of 150 Pa or less.

Another embodiment of the method for heating a circuit board according to the present invention is characterized in that the atmospheric gas blown from the blowing nozzle is sucked mainly after passing through the circuit board to attenuate the flow.

In the circuit board heating apparatus and heating method of the present invention, and the reflow furnace equipped with this heating apparatus, the atmospheric gas blown from the blowing nozzle has a sufficient blowing speed at the position of the circuit board, Since it does not reach the position of the blowout nozzle on the opposite side, the fluctuation of the furnace pressure accompanying the conveyance of the circuit board is reduced, so that high heating efficiency can be obtained and the consumption of atmospheric gas such as nitrogen is reduced. It is possible to reduce the operation cost.
Furthermore, since it becomes easy to set the temperature difference of the atmospheric gas sprayed on the upper and lower surfaces of the circuit board, it is possible to exhibit excellent performance in soldering such as lead-free solder.

Embodiments of the present invention will be described in detail with reference to the drawings.
(Description of the entire reflow furnace)
FIG. 1 shows an embodiment of a reflow furnace equipped with the heating device of the present invention. The circuit board on which the electronic component is mounted is transported horizontally in the direction of arrow A inside the reflow furnace by a transport device (not shown). The reflow furnace is composed of a 9 zone heating zone and a 2 zone cooling zone. The furnace body has a seal structure and is filled with an atmospheric gas such as nitrogen. In order to maintain sealing performance, the entry side (left side in FIG. 1) and the exit side (right side in FIG. 1) of the reflow furnace have a labyrinth structure.

  The circuit board is printed with normal solder or lead-free solder on the upper surface, and electronic components are mounted thereon, and in this embodiment, the circuit board is transported by a chain conveyor type transport device. The circuit board on which the electronic components are placed enters the furnace from the entry side of the reflow furnace, is preheated while being conveyed in the 1-6 zone of the heating zone, and is conveyed in the 7-9 zone of the heating zone. In addition, the solder is melted and soldered. Furthermore, it is cooled while being transported through the first and second zones of the cooling zone, and then transported from the reflow furnace exit side.

  Zones 1 to 9 of the heating zone of the reflow furnace are equipped with a heating device that blows and heats hot air on the upper surface side and the lower surface side of the circuit board to be conveyed. Moreover, in 1-6 zone which performs preheating, temperature control is performed so that the temperature of the atmospheric gas which sprays gradually from 1 zone may become high. The circuit board heated gradually in the 1st to 6th zones reaches the maximum temperature in the 7th to 9th zones, and the solder is melted and soldered. The structure of the heating device in each zone is substantially the same.

  After the soldering is performed in the 7 to 9 zones of the heating zone, the temperature of the circuit board is gradually lowered in the 1 to 2 zones of the cooling zone, and is carried out from the exit side of the reflow furnace. One zone of the cooling zone is provided with a heating device that heats the upper and lower surfaces of the circuit board to be conveyed, and the structure is substantially the same as the heating device of the 1 to 9 zones of the heating zone. The reflow device in the cooling zone 2 zone is provided with a heating device only on the upper side.

(Description of heating device)
Next, an embodiment of the heating apparatus of the present invention will be described with reference to FIG. FIG. 2 is a view showing a cross section of the heating zone 7 zone indicated by the arrow B in FIG. 1. However, the other heating zone zones have the same structure.

First, the structure of the heating device of this embodiment will be described.
The reflow furnace is covered with a shell 1 having a seal structure and filled with an atmospheric gas such as nitrogen. The circuit board 2 on which the electronic component is placed is transported to the front side of the paper by the transport device 3 installed substantially at the center of the shell 1. Heating devices having the same structure are respectively attached to the upper surface side and the lower surface side of the circuit board 2 to heat the upper surface and the lower surface of the circuit board 2 to be conveyed. Here, the upper heating device will be described as an example.

On the upper side of the circuit board 2, a blowing panel 11 having a hot air blowing nozzle 6 and a cylindrical suction port 7 is provided. A box-shaped heating device chamber 4 is formed by the blowing panel 11 and the shell 1. Yes.
Above the blowout panel 11, a suction chamber 5 connected to the blowout panel 11 via a cylindrical suction port 7 is installed. Further, a circulating fan 8 that is driven by a fan motor 9 to circulate the atmospheric gas in the shell 1 and an electric heater 10 that heats the circulating atmospheric gas are installed above the fan. The fan motor 9 is attached to the outside of the shell 1, but has a structure in which outside air does not flow in by the sealing device 12. A heating device is constituted by the above members.

Next, a method for heating the upper surface of the circuit board using this heating apparatus will be described.
The atmospheric gas in the shell 1 and below the blow-out panel 11 is sucked into the suction chamber 5 from the suction port 7 as indicated by an arrow C by the suction force of the circulation fan 8. Then, the sucked atmospheric gas flows left and right along the upper inner surface of the shell 1 by the circulation fan 8 and is blown out to both sides of the suction chamber 5 as indicated by an arrow D. At this time, the atmospheric gas is heated to a predetermined gas temperature by the electric heater 10.

  Then, the heated atmospheric gas is blown from the blowing nozzle 6 and blown to the upper surface of the circuit board 2 as indicated by an arrow E. Since the heating device chamber 4 is in a sealed state except for the blowing nozzle 6 and the suction port 7, the atmospheric gas blown to the left and right by the circulation fan 8 has no flow path other than the blowing nozzle 6, and the blowing nozzle 6. Can be strongly sprayed onto the upper surface of the circuit board 2. Thereafter, the atmospheric gas is again sucked into the suction chamber 5 from the suction port 7 and repeats the same circulation cycle.

As is clear from FIG. 2, in this embodiment, the flow path on the outlet side (positive pressure side) is disposed outside the flow path on the suction side (negative pressure side), thereby realizing an efficient flow of atmospheric gas. ing.
The suction pressure of the circulation fan 8 can be adjusted to control the atmospheric gas blowing speed at the position of the circuit board 2 to a predetermined value. Usually, a desired spraying speed can be obtained by setting the suction pressure to 150 Pa or lower.
The heating device on the lower surface side of the circuit board 2 has the same structure as the heating device on the upper surface side, and the heating method is the same.

(Explanation of blowout panel)
Next, an embodiment of the blowout panel 11 according to the present invention having a blowout nozzle and a suction port will be described. Fig.3 (a) is a figure which shows typically embodiment of the blowing panel of this invention, and FIG.3 (b) is a figure which shows a conventional blowing panel typically. In FIG. 3, the flow of the atmospheric gas blown from the upper blowing panel is indicated by an arrow, but the flow of the atmospheric gas blown from the lower blowing panel (not shown) is the same.

  As described above, the conventional blowout panel 111 as shown in FIG. 3B is not provided with means for controlling the flow rate of the atmospheric gas blown from the upper blowout nozzle 106, and therefore the circuit board 102. If the predetermined blowing speed is to be secured at the position, the blown-out atmospheric gas reaches the position of the lower blowing nozzle 106 on the opposite side.

On the other hand, in the blowing panel 11 of the present invention, as schematically shown in FIG. 3A, the suction port 7 is provided next to the blowing nozzle 6, and the atmospheric gas blown from the blowing nozzle 6. Can be attenuated by the suction force of the suction port 7 to control the flow velocity.
The flow velocity can be drastically reduced by adding a vector in a generally opposite direction for sucking in the atmospheric gas from the suction port 7 to the vector in which the atmospheric gas blown out from the blowing nozzle 6 travels. Moreover, a desired attenuation characteristic can be obtained by appropriately setting the size and the positional relationship between the blowing nozzle 6 and the suction port 7.

  As described above, the flow rate of the atmospheric gas blown out from the blow nozzle 6 is rapidly decelerated by the suction force from the suction port 7, and after passing through the position of the circuit board 2, reaches the position of the lower blow nozzle 6. The direction of the flow can be changed before, and it can flow out upward from the upper suction port 7. Although the details will be described later, the atmospheric gas blown from the blow nozzle 6 has a damping characteristic such that the flow velocity of the atmospheric gas is ½ or less of the initial velocity blown from the blow nozzle 6 at a position reaching the circuit board 2. In this case, it is considered that even if a flow rate sufficient for heating is taken at the position of the circuit board 2, a state where the position does not reach the position of the blowing nozzle 6 on the opposite side can be created.

  Next, FIG. 4 schematically shows the flow of the atmospheric gas when the blowout panel of the present embodiment is used. FIG. 4A shows a flow when the circuit board 2 exists, and FIG. 4B shows a flow when the circuit board 2 does not exist.

When the circuit board 2 is not present, the atmospheric gas blown out from the blowing nozzle 6 is sucked into the suction port 7 on the blowing side after traveling a longer distance than when the circuit board 2 is present. The general flow shape is the same. On the other hand, in the conventional blowing nozzle 106 as shown in FIGS. 8A and 8B, it is apparent that the shape of the flow of the atmospheric gas varies greatly depending on the presence or absence of the circuit board 102.
Therefore, the comparison between FIG. 4 and FIG. 9 proves that in this embodiment, the fluctuation of the furnace pressure due to the presence or absence of the circuit board is significantly reduced as compared with the conventional example.

  As described above, when the blowout panel 11 of the present invention is used, fluctuations in the furnace pressure in the case where the circuit board 2 is present and in the case where the circuit board 2 is not present are suppressed while obtaining a spraying speed sufficient for heating the circuit board 2. be able to. In addition, even when a temperature difference is provided between the upper and lower sides of the circuit board, mixing of the upper and lower atmospheric gases having a temperature difference can be suppressed, so that the upper and lower heating temperature difference can be easily provided.

(Example)
Next, specific examples of the blowout panel of the present invention and the measurement results of the flow velocity when the atmospheric gas is blown out using this blowout panel are shown. Fig.5 (a) is the figure seen from the arrow F of FIG. 2, and is the top view which looked at the blowing panel above the heating zone 7 zone from the lower side. The circuit board 2 is conveyed in the direction of arrow A in FIG.
FIG. 4B is a side view as seen from the arrow G in FIG. 4A. In the width direction of the reflow furnace, the circuit board 2, the rail 3a of the transfer device, the blowing panel 11, and the blowing nozzle 6 are shown. The positional relationship of the suction inlet 7 is shown.

In this embodiment, as shown in FIG. 5 (a), a suction-only line in which suction ports 7b are arranged is provided around the blow-out panel 11, and the blow-out nozzles 6 and the suction ports are arranged vertically and horizontally inside thereof. A mixed area in which 7a are alternately arranged is provided. As specific arrangements of the nozzles and the like in this mixed region, for example, it is conceivable to arrange the blowing nozzles 6 or the suction ports 7a in a staggered manner or in a lattice pattern.
This dedicated suction line is arranged only around the blow-out panel 11 in order to ensure a sufficient gas suction amount while keeping the flow of the atmospheric gas blown out from the blow-out nozzle 6 in the mixed region as small as possible. ing. However, when the atmospheric gas can be sufficiently circulated only by the suction amount of the suction port 7a in the mixed area, it is not necessary to provide it.

Specific dimensions of the blowout panel 11 of this embodiment are as follows.
Diameter of mixed region blowing nozzle 6: 4 mm
Diameter of suction port 7a: 9mm
Interval (pitch) between adjacent blowing nozzle 6 and suction port 7a: 10 mm
Diameter of suction line 7b for suction line: 12mm
Interval (pitch) between adjacent suction ports 7b: 16 mm
With the arrangement of the above dimensions, the circuit board 2 can be heated uniformly.

  The measurement result of the flow velocity of the atmospheric gas when the atmospheric gas is blown out using this blowout panel 11 is shown in the graph of FIG. The vertical axis represents the flow velocity (m / s) of the atmospheric gas, and the horizontal axis represents the distance (mm) from the blowing nozzle. A solid line graph shows actual measurement data in the blowing panel of this embodiment, and a dotted line graph shows an estimated value in the case of the conventional blowing panel when the flow rates at the circuit board positions are the same.

In this embodiment, the position of the circuit board is a point where the distance from the blowing nozzle is about 30 mm. Accordingly, the initial blowout speed of about 25 m / s is approximately 1/2 to 12-13 m / s at the position of the circuit board. And after that, the flow velocity continues to attenuate, and the flow velocity becomes zero at a point of a distance of 40 mm before reaching the blowout panel on the opposite side.
As a result of measurement under various conditions, if the flow rate of the atmospheric gas blown out from the blowout nozzle 6 is attenuated so as to be ½ or less of the blowout initial speed at the position reaching the circuit board 2, the circuit board It has been found that even if a flow rate sufficient for heating at the position 2 is taken, a state in which there is no fear of reaching the position of the blowing nozzle 6 on the opposite side can be created.

  On the other hand, since the conventional blowout panel does not have a damping mechanism as in the present invention, the flow rate at a distance of 30 mm at the position of the circuit board is about 80% of the blowout initial speed. After that, since the flow velocity is not greatly decelerated, the flow velocity does not become zero even when the distance of 60 mm, which is the position of the blowing nozzle on the opposite side, is reached.

(Other embodiments)
Next, other embodiments will be described.
Another embodiment of the heating device of the present invention shown in FIG. 7 includes an inner chamber 5a that encloses the atmospheric gas sucked from the suction port 7a in the mixed area, and a damper 15 for controlling the flow rate of the atmospheric gas. It is a heating device.
By adjusting the opening of the damper 15 and adjusting the suction force of the suction port 7a, the flow velocity of the atmospheric gas blown from the blowout nozzle 6 can be reduced with desired characteristics. Even if the damper 15 is squeezed, sufficient gas can be sucked from the suction port 7b of the dedicated suction line, so that the flow rate of the atmospheric gas blown from the blow nozzle 6 is not restricted. The adjustment of the damper 15 can be performed manually, or can be automatically controlled with an actuator.

In other embodiments of the blowout panel of the present invention, the flow of the atmospheric gas blown from the blowout nozzle is not significantly attenuated before reaching the circuit board, but is greatly attenuated after passing through the circuit board.
An example is shown in FIG. In the above-described embodiment, the blowout panel has a planar shape, and the blowout nozzle and the suction port are at the same height. However, in the blowout panel 11 shown in FIG. 6 is installed at a position closer to the circuit board 2 than the installation of 6. With this arrangement, the flow of the atmospheric gas blown from the blowing nozzle 6 is not sucked much until it reaches the position of the circuit board 2, and is sucked by the suction port 7 after passing through the circuit board 2 to greatly attenuate the flow. Is.
With this embodiment, it is possible to spray the circuit board at a high spray speed, and after passing through the spray position, the flow is rapidly attenuated and the flow velocity is made zero before reaching the opposite spray nozzle position. It is possible.

  Further, regarding the positional relationship between the blowout nozzle and the suction port, all arrangements and positional relationships are conceivable, and a mode in which the blowout nozzle is installed at a position closer to the circuit board than the suction port is also included in the present invention.

  Moreover, in the above-mentioned embodiment, although the heating apparatus of this invention is installed in both surfaces of a circuit board, it is also possible to combine this heating apparatus and other heating apparatuses, such as an electric heater. Furthermore, the present invention is not limited to the above-described embodiment, and various other embodiments are conceivable.

It is a schematic diagram showing the whole reflow furnace provided with the heating device of the present invention. It is sectional drawing which shows the structure of the heating apparatus of this invention. (A) is the figure which showed typically the outline of the blowing panel of this invention, and the flow of the blown-out atmosphere gas, (b) is the outline | summary of the conventional blowing panel, and the flow of the blown-out atmospheric gas FIG. It is the figure which showed the flow of the atmospheric gas blown out from the blowing panel of this invention, (a) shows the case where a circuit board exists, (b) shows the case where a circuit board does not exist. It is (a) top view and (b) side view which show the Example of the blowing panel of this invention. It is a graph which shows the flow velocity attenuation | damping characteristic of the atmospheric gas blown out from the blowing panel of this invention, and the conventional blowing panel. It is sectional drawing which shows other embodiment of the heating apparatus of this invention. It is a schematic diagram which shows other embodiment of the blowing panel of this invention. It is the figure which showed the flow of the atmospheric gas blown from the conventional blowing nozzle, (a) shows the case where a circuit board exists, (b) shows the case where a circuit board does not exist.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shell 2 Circuit board 3 Conveying device 3a Conveying rail 4 Heating device chamber 5 Chamber 5a Inner chamber 6 Blowing nozzle 7 Suction port 7a Suction port 7b Suction port 8 Circulating fan 9 Fan motor 10 Electric heater 11 Blowing panel 12 Sealing device 15 Damper 102 Circuit board 106 Blowing nozzle 107 Suction port 111 Blowing panel

Claims (16)

A heating device for heating a circuit board conveyed by a conveying device in a shell filled with atmospheric gas,
A circulation fan for circulating the atmospheric gas in the shell;
A heater for heating atmospheric gas circulated by the circulation fan;
A blowout nozzle that blows off the atmospheric gas heated by the heater and blows it onto the circuit board;
A suction port for sucking the atmospheric gas in the shell into the circulation fan;
With
Arrange the outlet nozzle and the suction port in a close proximity,
The circuit board heating apparatus according to claim 1, wherein the flow of the atmospheric gas blown from the blowing nozzle is attenuated with a predetermined attenuation characteristic by the suction force from the suction port.   2. The damping characteristic according to claim 1, wherein the atmospheric gas blown from the blow nozzle has a damping characteristic such that a flow velocity when the gas reaches the circuit board is ½ or less of an initial speed blown from the blow nozzle. The circuit board heating apparatus as described. In the case where the heating device is installed on both sides of the circuit board and both sides of the circuit board are heated,
2. The atmospheric gas blown from one of the blow nozzles is sucked into a suction port on the one blow nozzle side while changing the flow direction before reaching the blow nozzle on the opposite side. Or a circuit board heating apparatus according to 2;   4. The circuit board heating apparatus according to claim 1, wherein the blow-out nozzles and the suction ports are arranged alternately. 5.   5. The circuit board heating apparatus according to claim 1, wherein a nozzle port of the blowout nozzle and the suction port are arranged so as to be aligned in the same plane. 6.   The circuit board heating apparatus according to any one of claims 1 to 5, wherein a suction pressure from the suction port is a suction pressure of 150 Pa or less.   7. The circuit board heating apparatus according to claim 1, wherein the flow path for blowing out the atmospheric gas is disposed outside the flow path for sucking the atmospheric gas.   The new suction port for sucking atmospheric gas in the shell to the circulation fan in addition to the suction port is installed at a position not close to the blowout nozzle. The circuit board heating apparatus according to any one of the preceding claims.   The apparatus for heating a circuit board according to claim 9, further comprising a damper that adjusts a suction force from the suction port.   The circuit board heating apparatus according to any one of claims 1 to 9, wherein the atmospheric gas blown from the blow nozzle is sucked mainly after passing through the circuit board to attenuate the flow. .   A reflow furnace for soldering a circuit board using the circuit board heating apparatus according to claim 1. Filling the shell with atmospheric gas and heating while transporting the circuit board by the transport device,
Circulating the atmospheric gas in the shell with a circulation fan;
Heating the atmospheric gas circulated by the circulation fan with a heater;
Blowing the atmospheric gas heated by the heater using a blowing nozzle and spraying the circuit board;
Sucking atmospheric gas in the shell to the circulation fan using a suction port;
With
Arrange the outlet nozzle and the suction port in a close proximity,
A method for heating a circuit board, comprising: attenuating a flow of an atmospheric gas blown from the blowing nozzle with a predetermined damping characteristic by a suction force from the suction port.   The flow is attenuated so that the flow velocity when the atmospheric gas blown from the blow nozzle reaches the circuit board is equal to or less than ½ of the initial speed blown from the blow nozzle. The circuit board heating method according to claim. In heating both sides of the circuit board,
Before the atmospheric gas blown from one of the blow nozzles reaches the blow nozzle on the opposite side, the direction of the flow is changed and the flow is attenuated so that it is sucked into the suction port on the one blow nozzle side. The method for heating a circuit board according to claim 12 or 13, characterized in that:   The method for heating a circuit board according to any one of claims 12 to 14, wherein the atmospheric gas is sucked from the suction port at a suction pressure of 150 Pa or less.   16. The method for heating a circuit board according to claim 12, wherein the atmospheric gas blown from the blowing nozzle is sucked mainly after passing through the circuit board to attenuate the flow. .

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