Method for generating an airflow barrier in a reflow oven

Abstract

This invention provides a method for generating an airflow barrier in a reflow oven. [Solution] The reflow oven 100 is a continuous processing reflow oven and includes a heating processing zone 12 and a cooling processing zone 14. In each processing zone 12, 14, an airflow barrier Br is formed at each inlet opening 12(in) and 14(in) and each outlet opening 12(out) and 14(out). Each airflow barrier Br is formed by the atmospheric gas of the corresponding processing zone 12, 14. The airflow barrier Br is discharged from the barrier nozzle hole 56 toward the inside of the corresponding processing zone 12, 14, and the airflow barrier Br is taken into the atmospheric gas of the corresponding processing zone 12, 14.

Description

Technical Field

[0001] The present invention relates to a reflow furnace for soldering electronic components mounted on a printed circuit board to the board via reflow solder, and more particularly to a method for generating an airflow barrier in a reflow furnace.

Background Art

[0002] A reflow furnace generally has a plurality of processing zones partitioned by partition walls. Patent Documents 1 and 2 disclose a "vertical heating" type reflow furnace that blows a jet of atmospheric gas in the heating treatment zone onto the substrate from the vertical direction. The atmospheric gas in each processing zone is circulated within each processing zone.

[0003] Openings through which workpieces can pass are formed in the inlet, outlet, and partition walls of each processing zone of the reflow furnace. The openings in the inlet, outlet, and partition walls are always open. The workpiece carried into the reflow furnace is carried from one processing zone to the next through the openings in the partition walls.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Between adjacent processing zones, the atmospheric gas exchanges through the openings in the partition walls, which becomes a disturbance factor for the temperature control of the atmospheric gas in each processing zone. This means an increase in energy consumption for controlling the temperature of the atmospheric gas in each processing zone. The object of the present invention is to provide a method for generating an airflow barrier in a reflow furnace. [Means for solving the problem]

[0006] To achieve the aforementioned objectives, the present invention provides: In a reflow furnace having multiple processing zones, an airflow barrier is generated at at least one of the inlet and outlet openings of at least one of the processing zones by the atmospheric gas inside the processing zone. The present invention provides a method for generating an airflow barrier in a reflow oven, characterized in that the airflow barrier is discharged from the outlet of the airflow barrier toward the inside of the processing zone. [Brief explanation of the drawing]

[0007] [Figure 1] Schematic diagram illustrating the basic configuration of the reflow oven in the example. [Figure 2] This diagram shows the final heat treatment zone and the subsequent first cooling treatment zone included in the reflow furnace of the example. [Figure 3] Enlarged view showing the boundary between the final heat treatment zone and the subsequent first cooling treatment zone. [Figure 4] A side view of the nozzles of the atmosphere circulation units located in the heating and cooling zones. [Figure 5] Plan view of the end plate that forms the lower end surface of the atmosphere circulation unit located in the upper boiler. [Figure 6] Plan view of the end plate that forms the upper end surface of the atmosphere circulation unit located in the lower boiler. [Modes for carrying out the invention] [Examples]

[0008] Figure 1 is a schematic diagram illustrating the basic structure of the reflow oven 100 of the embodiment. The reflow oven 100 is a continuous processing reflow oven and has a heating region 8 and a subsequent cooling region 10, separated by two buffer zones 6 adjacent to the inlet 2 and outlet 4. The heating region 8 is composed of, for example, five heating zones 12. To identify the five heating zones 12, they are shown in order of No. 1, No. 2...No. 5 in the direction of flow of the workpiece Wp. The cooling region 10 is composed of, for example, two cooling zones 14. To identify the two cooling zones 14, they are shown in order of No. 1, No. 2 in the direction of flow of the workpiece Wp.

[0009] Openings 22 are formed in the partition walls 20 that separate the buffer zone 6, each heat treatment zone 12, and each cooling treatment zone 14, and each opening 22 is kept open at all times. The workpiece Wp is transported by an endless conveying chain 26 along a furnace workpiece transport path 24 that extends linearly through the openings 22 in the partition walls 20.

[0010] The reflow oven 100 is a vertical heating type reflow oven. The reflow oven 100 in this embodiment consists of an upper kettle 30 and a lower kettle 32, and the upper kettle 30 and the lower kettle 32 work together to form an inlet buffer zone 6, a heat treatment zone 12, a cooling treatment zone 14, and an outlet buffer zone 6. The upper kettle 30 and the lower kettle 32 are equipped with an atmosphere circulation unit 36 ​​(Figure 2) which has substantially the same structure.

[0011] Referring to Figure 2, the heating atmosphere circulation unit 36(h) has a circulation fan 38 driven by an electric motor M, a heater 40, and a nozzle 42, from which hot air is discharged vertically toward the furnace workpiece transport path 24. Soldering is performed by the heat of the jet discharged from the nozzle 42. The atmospheric gas within each heating zone 12 is circulated within each heating zone 12.

[0012] The cooling atmosphere circulation unit 36(c) has a circulation fan 44, a chiller 46, and a nozzle 48 driven by an electric motor M, and cold air is discharged vertically from the nozzle 48 toward the furnace workpiece transport path 24. The atmosphere gas cooled in each cooling zone 14 is circulated within each cooling zone 14. The arrow A shown in Figure 3 indicates the circulating gas discharged from nozzles 42 and 48. The basic structure of the heating atmosphere circulation unit 36(h) and the cooling atmosphere circulation unit 36(c) described above is the same as in the conventional design.

[0013] Figure 2 is an extracted view of the final heat treatment zone 12 (No. 5) and the first cooling treatment zone 14 (No. 1), and Figure 3 is an enlarged view of the boundary between the heat treatment zone 12 (No. 5) and the cooling treatment zone 14 (No. 1).

[0014] Each atmosphere circulation unit 36 ​​has enlarged nozzles 42 and 44 to form a barrier generating unit 50 located at the opening 22 of the partition wall 20. In the reflow furnace 100 of this embodiment, the barrier generating unit 50 is located outside the heat treatment zone 12 and the cooling treatment zone 14. The barrier generating unit 50 is an integral structure with the nozzles 42 and 44, and a portion of the atmospheric gas passing through the nozzles 42 and 44 is supplied to the barrier generating unit 50. Referring to Figure 3, the barrier generating unit 50 creates airflow barriers Br at the inlet and outlet openings 12(in) and 12(out) of the heat treatment zone 12 (No. 5) and the inlet and outlet openings 14(in) and 14(out) of the cooling treatment zone 14 (No. 1).

[0015] Each atmosphere circulation unit 36 includes an end face plate 52. FIG. 4 is a schematic view of the nozzles 42(44) constituting the lower end portion of the atmosphere circulation unit 36. FIG. 5 is a plan view of the end face plate 52(up) constituting the lower end face of the atmosphere circulation unit 36 disposed in the upper kettle 30. FIG. 6 is a plan view of the end face plate 52(down) constituting the upper end face of the atmosphere circulation unit 36 disposed in the lower kettle 32. The end face plate 52(up) located in the upper kettle 30 and the end face plate 52(down) located in the lower kettle 32 are collectively referred to as the end face plate 52. The main nozzle holes 54 located inside the processing zones 12, 14 and the barrier blowing nozzle holes 56 located at the openings 22 of the partition wall 20 are formed. The barrier blowing nozzle holes 56 constitute the barrier generation portion 50. A barrier air flow Br is discharged from the barrier blowing nozzle holes 56. Specifically, the barrier air flow Br is discharged obliquely toward the inside of each of the processing zones 12, 14.

[0016] As described above, in the reflow furnace 100 of the embodiment, barriers by the barrier air flow Br are formed at the inlet side openings 12(in), 14(in) and the outlet side openings 12(out), 14(out) of all the processing zones. Each of these air flow barriers Br enters the corresponding processing zones 12, 14 and is taken into the circulating atmosphere gas.

[0017] The atmosphere gas temperature-controlled in each of the processing zones 12, 14 is prevented from flowing out to the adjacent heat treatment zone 12 or the cooling treatment zone 14 or the buffer zone 6 by the air flow barrier Br. In particular, between the last heat treatment zone 12(No. 5) and the first cooling treatment zone 14(No. 1), it is possible to prevent the hot air discharged from the nozzles 42 and the barrier blowing nozzle holes 56 of the heat treatment zone 12(No. 5) from flowing into the cooling treatment zone 14(No. 1). Also, it is possible to prevent the cold air discharged from the nozzles 48 and the barrier blowing nozzle holes 56 of the cooling treatment zone 14(No. 1) from flowing into the heat treatment zone 12(No. 5).

[0018] As a result, it is possible to prevent the intrusion of the atmospheric gas from the adjacent heat treatment zone and the cooling treatment zones 12 and 14, which cause disturbances in the temperature control of each processing zone 12 and 14. Consequently, it is possible to reduce the energy consumption required for temperature control in each processing zone 12 and 14.

[0019] As described above, the embodiments of the present invention have been explained, but the present invention includes the following modification examples. (1) In the embodiment, the barrier blowing nozzle hole 56 is arranged in the opening 22 of the partition wall 20. However, the barrier blowing nozzle hole 56 may be arranged in the openings 12(in), 14(in), 12(out), and 14(out) on the inlet side and the outlet side of each processing zone 12 and 14, or may be arranged at a position slightly inside the corresponding processing zones 12 and 14 rather than the openings 12(in), 14(in), 12(out), and 14(out) on the inlet side and the outlet side. (2) It is arbitrary which processing zone 12 or 14 the barrier air flow Br is provided in. Similarly, it is also arbitrary which of the openings 12(in), 14(in), 12(out), and 14(out) on the inlet side and the outlet side of each processing zone 12 and 14 the barrier air flow Br is provided in. (3) In the embodiment, the barrier air flow Br is provided in the openings 12(in), 14(in) on the inlet side and the outlet side openings 12(out), 14(out) of all the processing zones 12 and 14 for heating and cooling. However, for example, it may be designed to provide the air flow barrier Br only in the outlet side opening 12(out) of the heat treatment zone 12 (No.5) adjacent to the cooling treatment zone 14. In addition to this, an air flow barrier Br may be provided in the inlet side opening 14(in) of the first cooling treatment zone 14(No.1). (4) It may be designed to provide the air flow barrier Br only in the inlet side opening 12(in) of the first heat treatment zone 12(No.1).

[0020] As described above, the embodiments and modification examples of the reflow furnace of the present invention have been explained. Needless to say, the reflow furnace of the present invention is applicable to both the flux treatment reflow furnace and the fluxless treatment reflow furnace.

Explanation of symbols

[0021] 100 Reflow Furnaces (Examples) 8. Heating area of ​​the reflow oven 10. Cooling area of ​​the reflow oven 12 Heat treatment zones 12 (in) Inlet opening of the heat treatment zone 12 (out) Outlet opening of the heat treatment zone 14 Cooling Processing Zones 14(in) Inlet opening of the cooling zone 14 (out) Outlet opening of the cooling zone 20 Partition Walls 22 Openings in partition walls 36(h) Atmosphere circulation unit for heating 36(c) Atmosphere circulation unit for cooling 42 Nozzle of the atmosphere circulation unit for heating 48 Nozzle of the cooling atmosphere circulation unit 50 Barrier flow generation section of the atmosphere circulation unit 52 End plate 54 Main nozzle holes 56 Barrier discharge nozzle holes Br Airflow Barrier

Claims

1. In a reflow furnace having multiple processing zones, an airflow barrier is generated at at least one of the inlet and outlet openings of at least one of the processing zones by the atmospheric gas inside the processing zone. A method for generating an airflow barrier in a reflow oven, characterized in that the airflow barrier is discharged from the outlet of the airflow barrier toward the inside of the processing zone.

2. The reflow furnace has a heating zone and a subsequent cooling zone. A method for generating an airflow barrier in a reflow furnace according to claim 1, wherein the airflow barrier is generated at the outlet side opening of the heat treatment zone.

3. A method for generating an airflow barrier in a reflow furnace according to claim 2, wherein the airflow barrier is generated at the inlet-side opening of the cooling processing zone.

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