JP2006173471A - Reflow soldering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflow soldering apparatus capable of stably controlling and managing a low oxygen concentration in a reflow furnace by reducing the amount of an inert gas supplied into the reflow furnace for controlling and managing the oxygen concentration in the reflow furnace and reducing the oxygen concentration in the reflow furnace even if the amount of the supplied inert gas is small. <P>SOLUTION: In this reflow soldering apparatus, while the inert gas is supplied into the reflow furnace having a transfer inlet at one end thereof and a transfer outlet at the other end thereof and having a plurality of heating units and cooling units between them to control the oxygen concentration in the reflow furnace, a printed wiring board on which electronic components are mounted via cream solder is transferred from the transfer inlet to the transfer outlet, and reflow is carried out by heating with the plurality of heating units to solder them. The passage for supplying the inert gas into the reflow furnace is disposed in a location wherein it is heated by the heating units, and thus the heated inert gas is supplied into the reflow furnace. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reflow soldering apparatus for mounting electronic components on a printed wiring board, and particularly to a lead-free solder having a high heat capacity, and a reflow soldering apparatus effective for mounting electronic parts, printed wiring boards, and the like. is there.

  FIG. 2 shows a schematic configuration of a conventional reflow soldering apparatus.

  The reflow soldering apparatus has a conveyance inlet 70 on one end side and a conveyance outlet 71 on the other end side, and an inert gas is introduced into a reflow furnace D having a plurality of heating units and cooling units therebetween. While supplying and controlling the oxygen concentration in the reflow furnace D, the printed wiring board 51 on which the electronic component 52 is mounted is transferred from the transfer inlet 70 in the reflow furnace D to the transfer outlet 71 via the cream solder. Reflow is performed by heating by a plurality of heating units in D and soldering is performed.

  The heating unit provided in the vicinity of the transfer inlet 70 functions as preheating, and subsequently, reflow is performed by the heating unit provided along the transfer path, so that a plurality of heating units are usually provided. Since the cooling unit plays a role of cooling the printed wiring board 51 on which the electronic component 52 is soldered, it is arranged on the transfer outlet 71 side in the transfer path, and at least one of the transfer units is transferred as shown in FIG. It is deployed just before the exit 71. Usually, an area where the heating unit is provided and heated is called a heating zone, and an area where the cooling unit is arranged and cooled is called a cooling zone.

  In the embodiment shown in FIG. 2, the heating unit is a hot air heating unit 53 that supplies hot air into the reflow furnace D, and the cooling unit is a cold air cooling unit 54 that supplies cold air into the reflow furnace D.

  The transfer inlet 70 and the transfer outlet 71 are respectively provided in the reflow furnace D through a labyrinth 55 having flow path resistance, and an inert gas such as nitrogen or helium is supplied into the reflow furnace D to supply the reflow furnace D. The oxygen concentration of the reflow furnace is controlled so that, when the printed wiring board 51 on which the electronic component 52 is mounted is soldered, an oxygen film is not generated in the solder portion and the solder is efficiently activated. The oxygen concentration in D is managed.

  In the embodiment shown in FIG. 2, the inert gas is supplied from the inert gas supply path 56 into the reflow furnace D through an optional hot air heating unit 53 and a cold air cooling unit 54. In other words, conventionally, although not shown, for example, supplying an inert gas in all of the heating zone and all of the cooling zone, supplying an inert gas in a part of the heating zone and part of the cooling zone, heating Various modes such as supplying an inert gas in a part of the zone and all the cooling zones, or supplying an inert gas only in a part or all of the heating zone have been adopted.

  The oxygen concentration in the reflow furnace D, the flow rate of hot air / cold air supplied from the hot air heating unit 53 / cold air cooling unit 54, the transfer speed of the transfer conveyor 57, etc. are set in advance, and the printed wiring board 51 on which the electronic components 52 are mounted is set. It is carried into the reflow furnace D from the transport inlet 70 by the transport conveyor 57 and transported through the reflow furnace D. In this process, the printed wiring board 52 is preheated by an arbitrary number of hot air heating units 53 and reflowed by an arbitrary number of hot air heating units 53.

  Then, the printed wiring board 51 on which the electronic component 52 is soldered is cooled by the cold air cooling unit 54 and is carried out from the reflow furnace D through the conveyance outlet 71.

During the reflow soldering step, an inert gas such as nitrogen or helium is supplied into the reflow furnace D from the inert gas supply path 56 at an arbitrary concentration. A labyrinth 55 having flow path resistance is installed at the transfer inlet 70 and the transfer outlet 71 of the reflow furnace D. This prevents the inert gas supplied into the reflow furnace D from flowing out of the furnace easily. In this way, when the printed wiring board 51 on which the electronic component 52 is mounted is soldered, the oxygen concentration in the reflow furnace D is prevented so that an oxygen film is not generated in the solder portion and the solder is efficiently activated. Management was done.
Japanese Patent Laid-Open No. 7-131149

  As described above, in the conventional reflow soldering apparatus, the inert gas is supplied from the inert gas supply path 56 into the reflow furnace D through an arbitrary heating zone and cooling zone. That is, conventionally, the inert gas is locally supplied into the reflow furnace D from one arbitrary zone or a plurality of zones.

  For this reason, in order to appropriately control and manage the oxygen concentration in the reflow furnace D, it is necessary to supply a large amount of inert gas into the reflow furnace D.

  The present invention solves such a problem in the conventional reflow soldering apparatus, makes it possible to control and manage the oxygen concentration in the reflow furnace D with a smaller supply amount of inert gas, Even if the supply amount of the inert gas is smaller, the oxygen concentration in the reflow furnace D can be kept lower, and thus the oxygen concentration in the low reflow furnace D can be stably controlled and managed. An object of the present invention is to provide a reflow soldering device that can be used.

  In order to achieve the above object, the present invention is inactive in a reflow furnace having a transfer inlet on one end side and a transfer outlet on the other end side, and having a plurality of heating units and cooling units between them. While supplying gas to control the oxygen concentration in the reflow furnace, the printed wiring board on which electronic components are mounted is transferred from the transfer inlet of the reflow furnace to the transfer outlet via cream solder, and the reflow furnace A reflow soldering device for performing reflow soldering by heating by the plurality of heating units in the inside, wherein a passage for supplying an inert gas into the reflow furnace is heated, and the heated inert gas is The present invention proposes a reflow soldering device that is supplied into a reflow furnace.

  Here, the heating of the passage for supplying the inert gas into the reflow furnace can be performed by the heating unit provided in the reflow furnace. For example, the passage for supplying the inert gas into the reflow furnace is arranged at a position heated by the heating unit, and the heated inert gas is thereby supplied into the reflow furnace. is there.

  According to the reflow soldering apparatus of the present invention, for example, the passage for supplying the inert gas into the reflow furnace is provided by arranging the passage for supplying the inert gas into the reflow furnace at a position heated by the heating unit. Heating. As a result, the heated inert gas is supplied into the reflow furnace, and the inert gas that has been expanded in volume by heating is supplied into the reflow furnace.

  In the conventional reflow soldering apparatus, as shown in FIG. 2, the inert gas is supplied from the outside at room temperature into the reflow furnace without being heated.

  According to the above-described reflow soldering apparatus of the present invention, the inert gas volume-expanded by heating as described above is supplied into the reflow furnace. Therefore, the oxygen concentration in the reflow furnace can be reduced by supplying a smaller amount of inert gas as compared with the conventional reflow soldering apparatus in which the inert gas is supplied into the reflow furnace without being heated from outside at room temperature. Control can be performed. If an inert gas in an amount equivalent to the conventional amount is supplied, the volume-expanded inert gas is supplied into the reflow furnace, so that the oxygen concentration in the reflow furnace is kept lower than in the conventional case. It becomes possible.

  In any of the reflow soldering apparatuses of the present invention described above, the opening of the passage for supplying the inert gas into the reflow furnace is in the region of the intermediate portion between the transfer inlet and the transfer outlet in the reflow furnace. It can be in the form of being arranged.

  In this way, the volume-expanded inert gas is supplied into the reflow furnace from the region of the intermediate portion between the transfer inlet and the transfer outlet in the reflow furnace. As a result, the pressure in the intermediate partial region of the reflow furnace can be increased. Then, the inert gas flows from the intermediate partial region where the pressure is high toward the transfer inlet and the transfer outlet, and it becomes easy to stably control and manage the oxygen concentration in the reflow furnace. .

  Further, in this configuration, the heating unit is a hot air heating unit that supplies hot air into the reflow furnace, and the cooling unit is a cold air cooling unit that supplies cold air into the reflow furnace, and the transfer inlet and the transfer outlet each have a labyrinth. To the reflow furnace by the hot air heating unit provided on the transfer inlet side across the position where the opening of the passage for supplying the inert gas into the reflow furnace is provided. The plurality of hot air heating units and the cold air cooling so that the supply of hot air and the supply of hot air and cold air to the reflow furnace by the hot air heating unit and the cold air cooling unit provided on the transfer outlet side are balanced. It can be configured to deploy units.

  In this way, it becomes possible to make the flow of the inert gas from the intermediate part region of the reflow furnace where the pressure is high as described above to the transport inlet direction and the transport outlet direction more uniform, This makes it possible to more stably control and manage the oxygen concentration in the reflow furnace.

  According to the present invention, the supply amount of the inert gas supplied into the reflow furnace for controlling and managing the oxygen concentration in the reflow furnace in the reflow soldering device is changed to the supply amount of the inert gas in the conventional reflow soldering device. In addition, the oxygen concentration in the reflow furnace can be kept lower even when the supply amount of the inert gas is smaller than that in the conventional manner, and the oxygen in the reflow furnace is thus low. A reflow soldering apparatus capable of stably controlling and managing the concentration can be provided.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a schematic configuration of a reflow soldering apparatus according to the present invention in which an intermediate portion between a conveyance inlet and a conveyance outlet is partially omitted.

  Constituent elements common to those in the conventional reflow soldering apparatus shown in FIG.

  The reflow soldering apparatus of the present invention has a structure in which the passage for supplying the inert gas into the reflow furnace is arranged at a position heated by the heating unit, and the heated inert gas is supplied into the reflow furnace. It has the characteristic in the point.

  In the embodiment shown in FIG. 1, an inert gas supply passage 61 (inner diameter: 4 mm) made of aluminum that extends into the reflow furnace D from the position of the transfer inlet 70 and the transfer outlet 71 and extends to the intermediate partial region is provided with a hot air heating unit 53. It is heated by receiving hot air from.

  And the inert gas (for example, nitrogen gas) heated by this is the opening of the inert gas supply passage 61 arrange | positioned in the area | region of the intermediate part between the conveyance inlet 70 and the conveyance outlet 71 in the reflow furnace D. The parts 62 and 62 are supplied into the reflow furnace D.

  Further, in the embodiment shown in FIG. 1, the reflow furnace by the hot air heating units 53, 53 arranged on the conveyance inlet 70 side across the position where the openings 62, 62 of the inert gas supply passage 61 are arranged. The supply of hot air into D and the supply of hot air and cold air into the reflow furnace D by the hot air heating unit 53 and the cold air cooling unit 54 arranged on the transfer outlet 71 side are balanced so as to be balanced. A hot air heating unit 53 and a cold air cooling unit 54 are provided.

  Specifically, the hot air heating unit 53 and the cold air cooling unit 54 that are respectively provided on the transfer inlet 70 side and the transfer outlet 71 side across the position where the openings 62 and 62 of the inert gas supply passage 61 are provided. By keeping the air volume, the air pressure, etc. at the same level, the hot air provided on the transfer inlet 70 side across the position where the openings 62, 62 of the inert gas supply passage 61 are provided. The balance between the supply of hot air into the reflow furnace D by the heating units 53 and 53 and the supply of hot air and cold air into the reflow furnace D by the hot air heating unit 53 and the cold air cooling unit 54 arranged on the transfer outlet 71 side. I am trying to remove.

  The reflow soldering by the reflow soldering apparatus of the present invention is performed as follows.

  The oxygen concentration in the reflow furnace D, the flow rate of hot air / cold air supplied from the hot air heating unit 53 / cold air cooling unit 54, the transfer speed of the transfer conveyor 57, etc. are set in advance, and the printed wiring board 51 on which the electronic components 52 are mounted is set. It is carried into the reflow furnace D from the transport inlet 70 by the transport conveyor 57 and transported in the reflow furnace D. In this process, the printed wiring board 51 is preheated by an arbitrary number of hot air heating units 53 at, for example, 160 to 180 ° C., and is reflowed by an arbitrary number of hot air heating units 53, for example, at 230 to 250 ° C. .

  Then, the printed wiring board 51 on which the electronic component 52 is soldered is cooled by a cold air cooling unit 54 in a temperature range lower than, for example, 100 ° C., and is carried out from the reflow furnace D through the conveyance outlet 71.

  During the reflow soldering process, the inert gas supply passage 61 is heated by receiving hot air from the hot air heating unit 53, and is thus supplied into the reflow furnace D from the openings 62 and 62 of the inert gas supply passage 61. The inert gas (for example, nitrogen gas) when heated is in a state of being heated and volume-expanded more than the normal temperature state.

  The inert gas (for example, nitrogen gas) volume-expanded in this way is supplied into the reflow furnace D from the region of the intermediate portion between the transfer inlet 70 and the transfer outlet 71 in the reflow furnace D as shown in FIG. Therefore, the pressure in the intermediate partial region of the reflow furnace D can be increased.

  Then, hot air is supplied into the reflow furnace D by the hot air heating units 53 and 53 provided on the transfer inlet 70 side across the position where the openings 62 and 62 of the inert gas supply passage 61 are provided. Since the supply of hot air and cold air into the reflow furnace D by the hot air heating unit 53 and the cold air cooling unit 54 arranged on the transport outlet 71 side is balanced, the intermediate partial region where this pressure is high It is possible to make the flow of the inert gas (for example, nitrogen gas) from the direction toward the conveyance inlet 70 toward the conveyance outlet 71 more uniform. As a result, the oxygen concentration in the reflow furnace D can be controlled and managed more stably.

  Thus, when the printed wiring board 51 on which the electronic component 52 is mounted is soldered, the oxygen concentration in the reflow furnace D is controlled so that an oxygen film is not generated in the solder portion and the solder is efficiently activated. It can be carried out.

  As a result, the inert gas (for example, nitrogen gas) is less inert gas (for example, nitrogen gas) than the conventional reflow soldering apparatus in which the reflow furnace is supplied without being heated from outside at room temperature. The oxygen concentration in the reflow furnace can be controlled by the supply amount of the gas), and the oxygen concentration in the reflow furnace D can be kept lower even if the inert gas supply amount is smaller than that in the prior art. Thus, the oxygen concentration in the low reflow furnace D can be stably controlled and managed.

  According to an experiment conducted by the inventor under the condition that the oxygen concentration in the furnace is maintained at 500 ppm by controlling the flow rate, nitrogen gas at normal temperature is reflowed from an arbitrary heating zone and cooling zone as shown in FIG. Compared with the case where the oxygen concentration control in the reflow furnace is performed by supplying into the furnace, the amount of nitrogen gas to be used is 50% when the reflow soldering apparatus of the present invention shown in FIG. 1 is used. In addition, it was possible to suppress the generation of an oxygen film on the solder portion at a level equivalent to that obtained by the conventional reflow soldering apparatus.

  In the embodiment shown in FIG. 1 described above, the inert gas supply passage 61 that enters the reflow furnace D from the position of the transfer inlet 70 and the transfer outlet 71 and extends to the intermediate partial region receives the hot air from the hot air heating unit 53. It was in a heated form. In the present invention, it is sufficient that the inert gas supply passage 61 is heated by receiving hot air from the hot air heating unit 53. Accordingly, for example, the inert gas supply passage 61 that enters the reflow furnace D from the middle part of the reflow furnace D receives the hot air from the hot air heating unit 53 and is heated. It is also possible to not enter the reflow furnace D from the position of the transfer inlet 70 and the transfer outlet 71 and extend to the intermediate partial region.

  Further, the inert gas supply passage 61 is heated by receiving the hot air from the hot air heating unit 53 and heated separately from the reflow furnace. As shown in FIG. 1, the opening 62 of the inert gas supply passage 61 that has received this heating is arranged in the region of the intermediate portion between the transfer inlet 70 and the transfer outlet 71 in the reflow furnace D. You can also

Sectional drawing which abbreviate | omitted and represented some schematic parts of the reflow soldering apparatus of this invention, and the intermediate part between a conveyance inlet and a conveyance outlet. Sectional drawing which abbreviate | omitted and represented some schematic parts of the conventional reflow soldering apparatus in the intermediate part between a conveyance inlet and a conveyance outlet.

Explanation of symbols

51 Printed Wiring Board 52 Electronic Component 53 Hot Air Heating Unit 54 Cold Air Cooling Unit 55 Labyrinth 56 Inert Gas Supply Path 57 Transport Conveyor 61 Inert Gas Supply Path 62 Inert Gas Supply Path Opening 70 Transport Inlet 71 Transport Outlet D Reflow Furnace

Claims (4)

An oxygen gas in the reflow furnace is supplied by supplying an inert gas into a reflow furnace having a transfer inlet at one end and a transfer outlet at the other end, and having a plurality of heating units and cooling units between them. While controlling the concentration, the printed wiring board on which electronic components are mounted via the cream solder is transported from the transport inlet to the transport outlet of the reflow furnace, and is heated by the plurality of heating units in the reflow furnace. A reflow soldering device for performing reflow soldering,
A reflow soldering apparatus, wherein a passage for supplying an inert gas into a reflow furnace is heated, and the inert gas heated thereby is supplied into the reflow furnace.   The reflow soldering apparatus according to claim 1, wherein heating of the passage for supplying the inert gas into the reflow furnace is performed by the heating unit provided in the reflow furnace.   The opening of the passage for supplying an inert gas into the reflow furnace is disposed in a region of an intermediate portion between the transfer inlet and the transfer outlet in the reflow furnace. The reflow soldering device described.   The heating unit is a hot air heating unit that supplies hot air into the reflow furnace, and the cooling unit is a cold air cooling unit that supplies cold air into the reflow furnace, and the transfer inlet and the transfer outlet are respectively connected to the reflow furnace via a labyrinth. Supply of hot air to the reflow furnace by a hot air heating unit provided on the transfer inlet side across the position where the opening of the passage for supplying the inert gas into the reflow furnace is provided. The hot air heating unit and the cold air cooling unit are arranged so as to be balanced with the supply of hot air and cold air to the reflow furnace by the hot air heating unit and the cold air cooling unit provided on the transfer outlet side. The reflow soldering apparatus according to claim 3, wherein the reflow soldering apparatus is provided.

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