JP2011143458A - Reflow apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflow apparatus which can reduce the supply of nitrogen gas and can prevent increase in concentration of oxygen caused by the intrusion of external air into a furnace. <P>SOLUTION: Gas within a furnace is sucked through a gas suction part in zones Z1 and Z10. The sucked gas is mixed in a gas mixer 41. The gas (flow amount A) from the gas mixer 41 is fed into a gas mixer 32. Air passed through a flow amount regulating valve 33 is fed into the gas mixer 32. Air introduced into the flow amount regulating valve 33 is output to the gas mixer 32 at a preset flow amount X. Control is performed so that a sucked amount A is equal to a flow amount B of gas delivered into a reflow furnace. Gas from the gas mixer 32 is fed into a nitrogen gas generator 36 through a filter 34 and a temperature regulating unit 35. The nitrogen gas from the nitrogen gas generator 36 is injected into a furnace through an ejection part in a zone Z7. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a reflow apparatus that performs reflow in a nitrogen gas atmosphere.

  A reflow apparatus is used in which a solder composition is supplied in advance to an electronic component or a printed wiring board, and the board is conveyed in a reflow furnace by a conveyor. The reflow apparatus includes a transport conveyor for transporting a substrate, and a reflow furnace main body to which a substrate as an object to be heated is supplied by the transport conveyor. For example, the reflow furnace is divided into a plurality of zones along a transfer path from a carry-in port to a carry-out port, and the plurality of zones are arranged in-line. The plurality of zones have roles such as a heating zone and a cooling zone depending on their functions.

Each of the heating zones has an upper furnace body and a lower furnace body. For example, hot air is blown against the substrate from the upper furnace body of the zone, and hot air is blown against the substrate from the lower furnace body, thereby melting the solder in the solder composition and Is soldered. In the reflow apparatus, desired soldering can be performed by controlling the surface temperature of an object to be heated, for example, a substrate, according to a desired temperature profile. Such a reflow apparatus can perform soldering in a non-contact manner, and can prevent oxidation because it performs soldering in an atmosphere of an inert gas such as nitrogen gas (N ₂ ).

  In Patent Document 1 below, the atmosphere enters from the inlet and outlet of the reflow furnace, and the nitrogen gas in the reflow furnace escapes to the outside, so that the concentration of the nitrogen gas in the furnace decreases and the nitrogen gas is replenished. It is described that the increase in running cost due to the constant running is solved.

  The apparatus described in Patent Document 1 sucks the gas in the furnace of the reflow apparatus, cools the nitrogen gas by the condenser, collects the solvent gas by liquefying, separates the oxygen gas by the nitrogen gas supply means, I'm trying to get it back.

Japanese Patent Laid-Open No. 04-251661

  In the case where the internal gas is sucked in to separate the oxygen and returned to the inside as in the apparatus described in Patent Document 1, the amount of gas discharged as a result of separating the oxygen gas is larger than the amount of the sucked gas. Decrease. This reduction in gas is supplemented by external air that enters the furnace from the inlet and outlet sides. As a result, there arises a problem that the oxygen concentration in the atmosphere in the furnace becomes high, and there arises a problem that the supply amount of nitrogen gas must be increased.

  Accordingly, an object of the present invention is to provide a reflow apparatus capable of reducing the running cost by reducing the supply amount of nitrogen gas while preventing the oxygen concentration in the furnace from becoming high.

In order to solve the above-described problems, the present invention is configured such that a reflow furnace is sequentially divided into a plurality of zones along a conveyance path of a heated object to be conveyed, and is conveyed by controlling the temperatures of the plurality of zones. In a reflow device for reflowing an object to be heated,
Gas outflow restriction portions respectively provided on the inlet side and the outlet side of the reflow furnace;
A gas suction portion that is provided in at least one of the inlet side and the outlet side of the reflow furnace, or at least one of the zone on the inlet side and the zone on the outlet side, and sucks the internal gas;
A gas discharge part for discharging gas into at least one of the plurality of zones;
A reflow apparatus including a nitrogen gas concentration adjusting unit that is supplied with gas sucked from a gas suction unit, generates nitrogen gas, and supplies the generated nitrogen gas to a gas discharge unit.
Preferably, a flow rate adjusting unit is provided to control the suction amount from the gas suction unit and the discharge amount from the gas discharge unit to be approximately equal.
Preferably, the gas discharge part is provided in one or a plurality of zones for performing reflow in the plurality of zones.
Preferably, the nitrogen gas concentration adjusting unit mixes the atmosphere with the supplied gas, generates nitrogen gas by separating oxygen from the gas mixed with the atmosphere, and the generated nitrogen gas is supplied to the gas discharge unit. Supply.
Preferably, the flow rate adjustment unit controls the amount of air mixture.
Preferably, an internal gas sucked from at least one zone of the reflow furnace is supplied, and a flux recovery device is provided in which the gas after flux recovery is discharged to at least one zone of the reflow furnace, and is supplied to the flux recovery device. The flow rate of the internal gas is set larger than the flow rate of the gas supplied to the nitrogen gas concentration adjusting unit.
Preferably, it is provided at two locations on the inlet side and outlet side of the reflow furnace, or at two locations on the inlet side zone and the outlet side zone, and has a gas suction portion for sucking the internal gas,
The oxygen concentration of the gas sucked from at least one of the gas suction portions is detected, and control is performed so as to increase the flow rate of the gas having the higher oxygen concentration among the flow rates of the gas sucked from the two gas suction portions. .

  According to the present invention, the nitrogen gas concentration adjusting unit generates nitrogen gas using a gas having a higher concentration of nitrogen than air. Therefore, when air is used, nitrogen gas can be generated efficiently, The supply amount of nitrogen gas can be reduced, and the cost can be reduced. According to the present invention, the amount of gas discharged into the furnace is reduced from the amount of sucked gas, and as a result, it is possible to prevent outside air from entering the furnace and increasing the oxygen concentration in the furnace. Furthermore, the pressure in the furnace can be kept substantially constant by making the amount of gas sucked and the amount of gas discharged almost equal. Furthermore, in the present invention, the gas suction portion is provided on at least one of the inlet side and the outlet side, and the gas discharge portion is provided, for example, in the central reflow zone, so that the oxygen concentration can be maintained substantially uniform inside the furnace. it can.

It is a basic diagram which shows the outline of the reflow apparatus which can apply this invention. It is a graph which shows an example of the temperature profile at the time of reflow. It is a basic diagram for demonstrating 1st Embodiment of this invention. It is a basic diagram for demonstrating the modification of 1st Embodiment of this invention. It is an approximate line figure for explaining a 2nd embodiment of this invention. It is a basic diagram for demonstrating the modification of the 2nd Embodiment of this invention. It is an approximate line figure for explaining a 3rd embodiment of this invention.

The best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described below. The description will be given in the following order.
<1. First Embodiment>
<2. Second Embodiment>
<3. Third Embodiment>
<4. Modification>

<1. First Embodiment>
"Example of reflow equipment"
FIG. 1 shows a schematic configuration excluding an outer plate of a reflow apparatus to which the present invention can be applied. A plurality of embodiments described below are preferable specific examples of the present invention, and various technically preferable limitations are given. However, the scope of the present invention will be particularly described in the following description. Unless stated to limit the invention, it is not limited to these embodiments.

  An object to be heated, on which electronic components for surface mounting are mounted on both sides of the printed wiring board, is placed on a conveyor, and is carried into the furnace body of the reflow apparatus from the carry-in entrance 11. For example, a conveyor having a configuration of a roller chain for conveyance conveys the object to be heated in a direction indicated by an arrow (left to right as viewed in FIG. 1), and the object to be heated is taken out from the carry-out port 12. Each of the carry-in ports 11 and 12 is provided with gas seal portions 21 and 22 as gas outflow restriction portions that prevent the atmospheric gas in the furnace from flowing out to the outside. As the gas seal portions 21 and 22, for example, a labyrinth seal mechanism can be used.

  A reflow furnace is sequentially divided into, for example, nine zones Z1 to Z9 along the conveyance path from the carry-in port 11 to the carry-out port 12, and these zones Z1 to Z9 are arranged in-line. Seven zones Z1 to Z7 from the inlet side are heating zones, and two zones Z8 and Z9 on the outlet side are cooling zones. A forced cooling unit 14 is provided in relation to the cooling zones Z8 and Z9. Furthermore, flux recovery units 17 and 18 are provided in relation to the cooling zones Z8 and Z9.

  The plurality of zones Z1 to Z9 described above controls the temperature of the object to be heated according to the temperature profile during reflow. FIG. 2 shows an outline of an example of a temperature profile. The horizontal axis represents time, and the vertical axis represents the surface temperature of a printed wiring board on which an object to be heated, such as an electronic component, is mounted. The first section is the temperature raising portion R1 where the temperature rises due to heating, the next section is the preheating (preheating) portion R2 where the temperature is substantially constant, the next section is the main heating (reflow) portion R3, and the last This section is the cooling unit R4.

  The temperature raising portion R1 is a period in which the substrate is heated from room temperature to a preheating portion R2 (for example, 150 ° C. to 170 ° C.). The preheating portion R2 is a period for performing isothermal heating, activating the flux, removing the oxide film on the surface of the electrodes and solder powder, and eliminating the heating unevenness of the printed wiring board. The main heating portion R3 (for example, 220 ° C. to 240 ° C. at the peak temperature) is a period in which the solder is melted and the joining is completed. In the main heating part R3, the temperature needs to be raised to a temperature exceeding the melting temperature of the solder. Even when the preheating portion R2 has passed, the main heating portion R3 needs to be heated to a temperature exceeding the melting temperature of the solder because there is uneven temperature rise. The last cooling part R4 is a period in which the printed wiring board is rapidly cooled to form a solder composition.

  In FIG. 2, curve 1 shows the temperature profile of lead-free solder. The temperature profile in the case of eutectic solder is shown by curve 2. Since the melting point of lead-free solder is higher than the melting point of eutectic solder, the set temperature in the preheating portion R2 is higher than that of eutectic solder.

  In the reflow apparatus, the zones Z1 and Z2 are mainly responsible for the temperature control of the temperature raising portion R1 in FIG. The zones Z3, Z4 and Z5 are mainly responsible for the temperature control of the preheating part R2. The zones Z6 and Z7 are responsible for temperature control of the main heating unit R3. The zone Z8 and the zone Z9 are responsible for temperature control of the cooling unit R4.

Each of the heating zones Z1 to Z7 has an upper furnace body 15 and a lower furnace body 16 each including a blower. For example, hot air (heated atmospheric gas) is blown against an object to be heated conveyed from the upper furnace body 15 and the lower furnace body 16 in the zone Z1. The object to be heated is one in which electronic components for surface mounting are mounted on both sides of a printed wiring board. Further, the upper furnace body 15 and the lower furnace body 16 are filled with an inert gas such as nitrogen gas (N ₂ ). In addition, you may irradiate infrared rays with a hot air.

  The upper furnace body 15 in the heating zones Z1 to Z7 includes, for example, a blower configured as a turbo fan, a heater configured by bending a plurality of heater wires, and a panel (heat storage member) having a large number of small holes through which hot air passes. The hot air that has passed through the small holes of the panel is blown against the object to be heated from above. The lower furnace body 16 has the same configuration as the upper furnace body 15.

  At the time of reflow, the object to be heated is conveyed at a predetermined speed by the conveying means such as a conveying chain through the gap between the upper furnace body and the lower furnace body, and the temperatures of the upper furnace body and the lower furnace body are preset. The temperature is controlled so that Furthermore, the air flow rate of the blower is also set to a predetermined value.

“First Embodiment”
As shown in FIG. 3, in the first embodiment of the present invention, in consideration of the flow of nitrogen gas inside the reflow furnace, the gas suction part and the carrier in the zone Z1 (temperature raising part) on the carry-in inlet 11 side are taken into account. A gas suction part is provided in the zone Z10 (cooling part) on the outlet 12 side, and the gas in the furnace is sucked from the gas suction part and led out to the outside. The gas sucked from the zones Z1 and Z10 is mixed in the gas mixer 41 via the flow rate adjusting valves 31 and 32, respectively. The flow rate of the flow rate adjusting valve 31 is adjusted by a control signal C1 for adjusting the flow rate. The flow rate of the flow rate adjusting valve 32 is adjusted by a control signal C2 for adjusting the flow rate.

  Note that the configuration shown in FIG. 3 schematically depicts the reflow apparatus shown in FIG. However, the number of zones is increased by one. In FIG. 1, two zones Z6 and Z7 are in charge of the main heating (reflow) portion, whereas in FIG. 3, three zones Z6, Z7 and Z8 are main. I am in charge of the heating section. Further, the flux collecting device is omitted in FIG.

  The gas (flow rate A) from the gas mixer 41 is supplied to the gas mixer 42. The atmosphere that has passed through the flow rate adjustment valve 33 is supplied to the gas mixer 42. The atmosphere that has entered the flow rate adjusting valve 33 is output to the gas mixer 42 with the set flow rate X. The gas mixer 42 uniformly mixes the gas sucked from the furnace and the atmosphere from the flow rate adjustment valve 33. The flow rate adjustment valve 33 constitutes a flow rate adjustment unit, and the flow rate is adjusted by a control signal for flow rate adjustment.

  As will be described later, the flow rate of gas discharged from the inside of the furnace, for example, from the gas discharge portion provided in the zone Z7 of the main heating portion (referred to as discharge amount as appropriate) is denoted as B. The flow rate adjusting unit including the flow rate adjusting valve 33 outputs to the mixer 32 the amount X of air that is the flow rate of the gas output from the gas mixer 41 so that the suction amount A and the discharge amount B are substantially equal. To do. This additional amount X is determined in consideration of the conversion efficiency of the nitrogen gas generator 37.

  The control signal for adjusting the flow rate can be generated, for example, by measuring the flow rates A and B with a flow meter. As another method, a method of generating a control signal by measuring a flow rate B (<A) when concentration adjustment is not performed in advance and obtaining a difference between the flow rates A and B may be employed. Furthermore, the amount of oxygen removed by the nitrogen gas concentration adjusting unit may be measured in advance and a control signal may be generated from the measurement result.

  Gas output from the gas mixer 42 is supplied to the filter 34. The filter 34 preliminarily filters and removes components, moisture, oil, etc. that do not want to flow into the downstream nitrogen gas generator 37 such as dust and dust in the gas. The gas that has passed through the filter 34 is supplied to the nitrogen gas generator 37 via the compressor 35 and the temperature adjustment unit 36.

  An example of the nitrogen gas generator 37 is a membrane separation nitrogen gas generator. Further, although not shown, hydrogen gas may be mixed with nitrogen gas in order to reduce the oxygen concentration of the generated nitrogen gas. In this method, the supply amount of hydrogen gas may be controlled in order to detect the oxygen concentration in the furnace and keep the oxygen concentration in the furnace substantially constant.

  The membrane-separated nitrogen gas generator is one in which hollow fiber membranes made of polymer polyimide are bundled and stored in a pressure-resistant container. Compressed air is supplied from one end of the pressure vessel. Nitrogen and oxygen enriched air (oxygen-rich gas) are separated by utilizing the difference in speed (relative permeability) at which each molecule such as nitrogen and oxygen in the compressed air permeates through the hollow fiber membrane. That is, as compressed air passes through the inside of the hollow fiber membrane, fast gases such as oxygen, water vapor, and carbon dioxide permeate the membrane and are discharged from the container as oxygen-rich gas. Concentrated nitrogen gas is recovered as dry nitrogen from the opposite outlet of the hollow fiber membrane at almost the same pressure as the supply pressure.

Nitrogen gas compressed by the compressor 35 is supplied to the temperature adjustment unit 36. When such a membrane-separated nitrogen gas generator is used as the nitrogen gas generator 37, there is a temperature at which the nitrogen gas is efficiently separated, so that the nitrogen gas generator 37 is supplied by the temperature adjustment unit 36. The gas temperature is controlled. The filter 34, the compressor 35, the temperature adjustment unit 36, and the nitrogen gas generator 37 constitute a nitrogen gas concentration adjustment unit. Nitrogen gas from the nitrogen gas generator 37 is injected into the furnace from, for example, the discharge part of the zone Z7 of the reflow device, and the atmosphere in the furnace is made inert gas. The nitrogen gas discharged into the furnace is preferably a high-purity nitrogen gas having, for example, oxygen of 10 ppm (parts per million) or more and 100 ppm or less.

  In the present invention, not only the membrane separation system, but also the PSA system that generates nitrogen gas using the difference in adsorption power of nitrogen and oxygen to micropores such as zeolite and activated carbon, and the difference in boiling point between oxygen and nitrogen are utilized. Nitrogen gas may be generated using a separation method or the like.

  As described above, the discharge amount B of nitrogen gas discharged from the discharge portion of the zone Z7 of the reflow apparatus into the furnace is measured or estimated, and the nitrogen gas with respect to the difference (A−B) between the suction amount A and the discharge amount B. The amount of air X to be added is calculated taking into account the conversion efficiency of the generator 37. The flow rate adjustment valve 33 is controlled by a control signal so that the amount X of air is output.

  With this control, an amount of nitrogen gas substantially equal to the amount of gas sucked from the furnace of the reflow apparatus can be discharged into the furnace. As a result, the concentration of nitrogen gas in the furnace can be increased, that is, the oxygen concentration can be decreased. Since the nitrogen gas generator 37 generates nitrogen gas using a gas having a higher nitrogen concentration than air, the nitrogen gas generator 37 can efficiently generate nitrogen gas when using air.

  Since the nitrogen gas generator 37 separates oxygen when generating nitrogen gas, the amount of gas decreases due to generation of nitrogen gas. In the mixer 32, an amount X of atmosphere necessary to supplement the decreasing amount of nitrogen gas is added. As a result, the amount of nitrogen gas in the furnace can be reduced, the pressure in the furnace can be reduced, the atmosphere can enter from the carry-in port 11 or the carry-out port 12, and the concentration of nitrogen gas in the furnace can be prevented from lowering. That is, the pressure inside the reflow furnace can be made substantially constant.

  In the first embodiment of the present invention described above, an amount of nitrogen gas substantially equal to the amount of gas sucked from the furnace of the reflow apparatus can be discharged into the furnace. As a result, the oxygen concentration in the furnace can be reduced. Furthermore, the amount of nitrogen gas in the furnace can be reduced, the pressure in the furnace can be reduced, the atmosphere can enter from the inlet 11 or the outlet 12 and the concentration of nitrogen gas in the furnace can be prevented from being reduced, The internal gas can hardly flow out to the outside. Furthermore, in the first embodiment of the present invention, nitrogen gas is discharged into the zone Z7 of the main heating section, and the internal gas is sucked from the zone Z1 on the carry-in side and the zone Z10 on the carry-out side. With this configuration, nitrogen gas can be circulated throughout the reflow furnace. Furthermore, since the gas to be sucked is less contaminated than the gas sucked from the main heating unit, the filter 34 can be prevented from being dirty.

  Furthermore, in the first embodiment of the present invention, the flow rate adjusting valves 31 and 32 control the amount of gas sucked from the zones Z1 and Z10. For this control, oximeters 28 and 29 are provided. The oxygen concentration meter 28 measures the oxygen concentration of the gas taken out from any one of the zones Z1, Z2, Z3, Z4 and Z5. That is, the oxygen concentration of the gas supplied to the flow rate adjusting valve 31 or a concentration close to the oxygen concentration of the gas is measured. The oxygen concentration meter 29 measures the oxygen concentration of the gas taken out from any one of the zones Z9 and Z10. That is, the oxygen concentration of the gas supplied to the flow rate adjusting valve 32 or a concentration close to the oxygen concentration of the gas is measured.

  A detection signal Sa indicating the oxygen concentration measured by the oxygen concentration meter 28 and a detection signal Sb indicating the oxygen concentration measured by the oxygen concentration meter 29 are supplied to a controller (not shown), and the controller generates control signals C1 and C2. . The detection signal Sa and Sb are used to detect the higher oxygen concentration and increase the flow rate of the gas having the higher oxygen concentration. In this case, the gas flow rate from the gas mixer 41 may be kept constant.

  Note that the oxygen concentration meter need not be provided in relation to the two paths supplied to the gas mixer 41 as in this example. An oxygen concentration meter may be arranged in one path (zone Z2 or Z9). In that case, the oxygen concentration is compared with a predetermined threshold value to determine whether the oxygen concentration is high or low.

  In addition, as shown in FIG. 4, you may make it inhale the gas from the inner side of the gas seal part 21 of an inlet side, and the inner side of the gas seal part 22 of an outlet side, and may discharge | emit the nitrogen gas generated in the zone Z7.

<2. Second Embodiment>
As shown in FIG. 5, the second embodiment of the present invention is different from the configuration of the first embodiment described above in that a flux recovery unit 38, a blower (blower) 39, a gas branching device 40, and a gas mixing unit are used. A device 41 is added.

  A gas suction section is provided in the zone Z1 (temperature raising section) on the carry-in entrance 11 side and a zone Z10 (cooling section) on the carry-out exit 12 side, and the gas in the furnace is sucked from the gas suction section to the outside. Derived. The gas sucked from the zones Z1 and Z10 is mixed in the gas mixer 41. The gas from the gas mixer 41 is supplied to the flux recovery unit 38. The flux recovery unit 38 cools the atmospheric gas taken out from the furnace, aggregates the flux components in the atmospheric gas, and recovers the liquid flux.

  The gas after flux recovery from the flux recovery unit 38 is supplied to the blower 39. The blower 39 creates a gas flow, and the gas flows in the pipe at a desired speed. The output gas from the blower 39 is supplied to the gas branching device 40. The gas branching device 40 branches the gas into two paths. That is, a first path for supplying gas to the gas mixer 42 and a second path for supplying gas to the gas mixer 42 are formed.

  Similarly to the first embodiment described above, the gas mixer 42 is supplied with the amount X of air set by the flow rate adjusting valve 33. The gas mixer 42 uniformly mixes the amount D of gas from the gas branching device 40 and the amount X of atmosphere from the flow rate adjusting valve 33. As in the first embodiment, the amount X of the atmosphere to be added is calculated in consideration of the conversion efficiency of the nitrogen gas generator 37 with respect to the difference (AB) between the suction amount A and the discharge amount B, The flow rate adjustment valve 33 is controlled by a control signal so that the amount X of air is output.

  The gas from the gas mixer 42 is supplied to the nitrogen gas generator 37 through the filter 34, the compressor 35 and the temperature adjustment unit 36. Nitrogen gas from the nitrogen gas generator 37 is supplied to the gas mixer 43. The gas (flow rate E) branched by the gas branching device 40 is supplied to the gas mixer 43. The output gas (flow rate B) of the gas mixer 43 is discharged from the discharge part of the zone Z7 into the furnace.

  The gas branching device 40 is provided because the flow rate of the gas for collecting the flux is considerably larger than the flow rate of the gas for generating the nitrogen gas. For example, if the gas flow rate C from the blower 39 is 1000 liters / minute, the gas flow rate D to the gas mixer 42 is 250 to 350 liters / minute, and the gas flow rate E to the gas mixer 42 is 750 to 650 liters. / Min. The amount X of air is controlled so that the flow rate of gas from the nitrogen gas generator 37 to the gas mixer 42 is 250 to 350 liters / minute. Therefore, the flow rate B of nitrogen gas discharged from the discharge part of the zone Z7 of the reflow device is 1000 liters / minute.

  In the second embodiment of the present invention described above, as in the first embodiment, an amount of nitrogen gas substantially equal to the amount of gas sucked from the furnace of the reflow apparatus can be discharged into the furnace. As a result, the oxygen concentration in the furnace can be reduced. Furthermore, in the second embodiment of the present invention, the nitrogen concentration is high and the nitrogen gas is generated by using the gas from which the flux has been removed. Therefore, when the air is used, the nitrogen gas is efficiently used. It can generate | occur | produce and the grade which the filter 34 by a flux gets dirty can be suppressed. Furthermore, as in the first embodiment, the pressure in the furnace can be kept substantially constant.

  In the configuration shown in FIG. 5, the gas branching unit 40 forms two paths for the gas after flux recovery. However, as shown in FIG. 6, a flux recovery path may be provided separately from the nitrogen gas concentration adjustment path. That is, with respect to the configuration shown in FIG. 4, the internal gas is guided to the flux recovery unit 38 from the gas suction portion provided in the zone Z6, the output gas of the flux recovery unit 38 is supplied to the blower 39, and the output gas of the blower 39 is supplied. The air is discharged to the zone Z6 (may be another zone). Also in the configuration shown in FIG. 6, the flow rate of the gas flowing through the flux recovery unit 38 and the blower 39 is set larger than the flow rate of the gas flowing through the nitrogen gas concentration adjustment path.

<3. Third Embodiment>
As shown in FIG. 7, the third embodiment of the present invention differs from the first and second embodiments described above in that an oxygen concentration meter is provided in a gas pipe. That is, the oxygen concentration meter 29 is provided in the gas path led out from the zone Z1, and the oxygen concentration meter 30 is provided in the gas path led out from the zone Z10. The oxygen concentration meters 29 and 30 may be provided in front of the flow rate adjusting valves 31 and 32 or may be provided on the output side of the gas mixer 41. Furthermore, the structure which provides either the oxygen concentration meter 29 and 30 may be sufficient.

<4. Modification>
Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. For example, the number of gas suction portions is not limited to two, and gas may be sucked from three or more zones. Similarly, the discharge part of nitrogen gas is not restricted to one place. However, it is effective to exhale the gas to one or more zones of the main heating unit that performs reflow. Further, in order to increase the pressure inside the reflow furnace, nitrogen gas may be supplementarily supplied to the zone of the main heating unit through another path.

DESCRIPTION OF SYMBOLS 11 ... Carry-in port 12 ... Carry-out port 14 ... Forced cooling unit 15 ... Upper furnace body 16 ... Lower furnace body Z1-Z10 ... Zone 21,22 ... Gas seal part 40 , 41, 42, 43 ... Gas mixer 31, 32, 33 ... Flow rate adjusting valve 37 ... Nitrogen gas generator 38 ... Flux recovery unit 40 ... Gas branching device

Claims (7)

In the reflow apparatus for reflowing the heated object to be conveyed by sequentially dividing the reflow furnace into a plurality of zones along the conveyance path of the heated object to be conveyed, and controlling the temperature of the plurality of zones,
Gas outflow restriction portions respectively provided on the inlet side and the outlet side of the reflow furnace,
A gas suction portion that is provided in at least one of the inlet side and the outlet side of the reflow furnace, or at least one of the zone on the inlet side and the zone on the outlet side, and sucks an internal gas;
A gas discharge part for discharging gas into at least one of the plurality of zones;
A reflow apparatus comprising: a nitrogen gas concentration adjusting unit that is supplied with gas sucked from the gas suction unit, generates nitrogen gas, and supplies the generated nitrogen gas to the gas discharge unit.   The reflow apparatus according to claim 1, further comprising a flow rate adjusting unit that controls the suction amount from the gas suction unit and the discharge amount from the gas discharge unit to be substantially equal.   The reflow apparatus according to claim 1 or 2, wherein the gas discharge unit is provided in one or a plurality of zones for performing reflow in the plurality of zones.   The nitrogen gas concentration adjusting unit mixes the atmosphere with the supplied gas, generates nitrogen gas by separating oxygen from the gas mixed with the atmosphere, and supplies the generated nitrogen gas to the gas discharge unit The reflow apparatus according to claim 1, 2, or 3.   The reflow apparatus according to claim 1, 2, 3, or 4, wherein the flow rate control unit controls the amount of air mixture. An internal gas sucked from at least one zone of the reflow furnace is supplied, and a flux recovery device is provided in which the gas after flux recovery is discharged to at least one zone of the reflow furnace,
The flow rate of the internal gas supplied to the flux recovery device is set larger than the flow rate of the gas supplied to the nitrogen gas concentration adjusting unit. Reflow device. Provided at two places on the inlet side and outlet side of the reflow furnace, or two places on the inlet side and the zone on the outlet side, and having a gas suction portion for sucking the gas inside;
The oxygen concentration of the gas sucked from at least one of the gas suction portions is detected, and the flow rate of the gas having the higher oxygen concentration is increased among the flow rates of the gas sucked from the two gas suction portions. The reflow apparatus according to claim 1, wherein the reflow apparatus is controlled.

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