Gas control system for reflow oven, and reflow oven

Abstract

This invention discloses a gas control system for a reflow oven. The oven chamber includes a preheating zone, a peaking zone, and a cooling zone. The gas control system includes an oxygen detection device, a first valve device, a second valve device, and a controller. The controller is configured to control the opening of the first valve device and / or the second valve device when the oxygen concentration detected by the oxygen detection device does not meet a preset value. This adjusts the flow rate of the working gas and / or air entering the peaking zone to ensure that the oxygen concentration in the peaking zone meets the preset value. The gas control system and reflow oven of this invention first perform coarse adjustment of the gas in the oven chamber to bring the oxygen concentration approximately near the preset value. Then, the first and second valve devices precisely adjust the oxygen concentration in the peaking zone of the oven chamber. Thus, even though the amount of oxygen in the air entering the oven chamber is variable, it does not affect the oxygen concentration in the peaking zone, thereby consistently improving the soldering quality of the circuit board.

Description

[Technical Field]

[0001] This case relates to the field of reflow ovens, and particularly to gas control systems for reflow ovens and reflow ovens. [Previous Technology]

[0002] In the manufacturing process of printed circuit boards, electronic components are typically mounted onto the circuit board through a process known as "reflow soldering." In a typical reflow soldering process, solder paste (e.g., solder grease) is deposited onto selected areas of the circuit board, and the wires of one or more electronic components are inserted into the deposited solder paste. The circuit board is then passed through a reflow oven, where the solder paste is reflowed in a heated zone (i.e., heated to a melting or reflow temperature) and then cooled in a cooled zone to electrically and mechanically connect the wires of the electronic components to the circuit board. As used herein, the term "circuit board" includes any type of substrate element for electronic components, such as a chip substrate.

[0003] In reflow ovens, air or a substantially inert gas (such as nitrogen) is typically used as the working gas, and the oven chamber is filled with this working gas. The circuit boards to be soldered are conveyed through the oven chamber via a conveyor, and soldering is performed in the working gas. For reflow ovens using a substantially inert gas as the working gas, depending on the circuit boards' process requirements, a gas control system is typically needed to maintain the oxygen concentration in the working gas within a certain range in the oven chamber. [Summary of the Invention]

[0004] The objective of this invention in a first aspect is to provide a gas control system for a reflow oven, the reflow oven having a gas chamber containing gas, the gas including oxygen and a working gas, the furnace chamber including a preheating zone, a peak zone, and a cooling zone, the gas control system comprising: an oxygen detection device configured to detect the oxygen concentration in the peak zone; a first valve device configured to controllably connect a working gas source to the peak zone of the furnace chamber; a second valve device configured to controllably connect an air source to the peak zone of the furnace chamber; and a controller communicatively connected to the oxygen detection device, the first valve device, and the second valve device, the controller being configured to control the opening of the first valve device and / or the second valve device when the oxygen concentration detected by the oxygen detection device does not meet a preset value, so as to adjust the flow rate of the working gas and / or air input into the peak zone of the furnace chamber to make the oxygen concentration in the peak zone meet the preset value.

[0005] According to the first aspect above, the gas control system includes a mixing pipeline, the mixing pipeline includes a first inlet, a second inlet and at least one outlet, the working gas source is in fluid communication with the first inlet through the first valve device, the air source is in fluid communication with the second inlet through the second valve device, and the at least one outlet is in fluid communication with the peak region.

[0006] According to the first aspect above, the peak region includes three sub-peak regions, the three sub-peak regions including a central sub-peak region located in the middle and two side sub-peak regions located on both sides of the central sub-peak region; the oxygen detection device is configured to detect the oxygen concentration in the central sub-peak region; the at least one outlet includes two outlets, the two outlets being in fluid communication with the two side sub-peak regions respectively.

[0007] According to the first aspect above, the gas control system further includes: a third valve device configured to fluidly connect the working gas source to the preheating zone of the furnace; the opening degree of the third valve device remains unchanged during the operation of the reflow oven.

[0008] According to the first aspect above, the preheating zone includes several sub-preheating zones, and the working gas source is controllably fluidly connected to a sub-preheating zone that is second farthest from the peak zone through the third valve device.

[0009] According to the first aspect above, the gas control system further includes: a fourth valve device, the fourth valve device being configured to fluidly connect the working gas source with the cooling zone of the furnace; the opening degree of the fourth valve device is determined according to the preset value.

[0010] According to the first aspect above, the cooling zone includes several sub-cooling zones, and the working gas source is controllably fluidly connected to a sub-cooling zone that is second farthest from the peak zone through the fourth valve device.

[0011] According to the first aspect above, the controller is configured to: determine an adjustment range based on a preset value of the oxygen concentration; when the oxygen concentration detected by the oxygen detection device is greater than the maximum value of the adjustment range, increase the opening of the first valve device to increase the flow rate of the working gas input into the peak region of the furnace so that the oxygen concentration reaches the preset adjustment range; when the oxygen concentration detected by the oxygen detection device is less than the minimum value of the adjustment range, increase the opening of the second valve device to increase the flow rate of oxygen input into the peak region of the furnace so that the oxygen concentration reaches the preset adjustment range; when the oxygen concentration detected by the oxygen detection device is within the preset adjustment range, adjust the opening of the first valve device and the second valve device so that the oxygen concentration in the peak region meets the preset value.

[0012] According to the first aspect above, the first valve device, the second valve device, the third valve device and the fourth valve device are flow control valves.

[0013] The object of the second aspect of this invention is to provide a reflow oven, comprising: a furnace chamber including a preheating zone, a peaking zone and a cooling zone, the furnace chamber containing a gas including oxygen and a working gas; and a gas control system as described in the first aspect.

Implementation Method

[0018] Various specific embodiments of this invention will now be described with reference to the accompanying drawings, which form part of this specification. It should be understood that although terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer," are used herein to describe various exemplary structural parts and elements, their use is merely for illustrative purposes and is based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed herein can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be considered as limiting.

[0019] Figure 1A is a simplified schematic diagram of an embodiment of the reflow oven of this invention, showing a view from the side of the reflow oven. Figure 1B is a gas flow diagram in the gas control system of the reflow oven. As shown in Figures 1A and 1B, the reflow oven 110 includes a furnace chamber 112 and a gas control system 100. The furnace chamber 112 includes a preheating zone 101, a peaking zone 103, and a cooling zone 105, which are arranged sequentially along the length of the furnace chamber 112 and are in fluid communication. The gas control system 100 is in fluid communication with the furnace chamber 112 to regulate the working gas atmosphere in the furnace chamber 112. The reflow oven 110 also includes a conveying device 118, which extends through the furnace chamber 112 along the length of the furnace chamber 112, for feeding the circuit board to be processed from the left end of the furnace chamber 112 into the furnace chamber 112, processing it sequentially through the preheating zone 101, the peaking zone 103, and the cooling zone 105, and then outputting the processed circuit board from the right end of the furnace chamber 112. When soldering some circuit boards, reflow ovens require a working gas that is primarily inert (e.g., nitrogen). The following explanation will use nitrogen as the working gas. It should be noted that Figures 1A and 1B show views from the side of the reflow oven 110. For ease of explanation, the outer casing used to cover the front and rear sides of the furnace chamber 112 has been removed in Figure 1.

[0020] Heating devices (not shown in the figure) are respectively provided in the preheating zone 101 and the peak zone 103. In the embodiment shown in Figure 1A, the preheating zone 101 includes nine sub-preheating zones Z01-Z09, and the peak zone 103 includes three sub-peak zones Z10-Z12. The sub-preheating zones Z01-Z09 and the sub-peak zones Z10-Z12 are continuously connected, and the temperature gradually increases. "Continuously connected" means that these sub-regions are arranged sequentially according to their numerical order. For example, the sub-peak zones include a central sub-peak zone Z11 and side peak zones Z10 and Z12 located on both sides of the central sub-peak zone Z11. The side peak zone Z10 is located between the sub-preheating zone Z09 and the central sub-peak zone Z11. In the preheating zone 101, the circuit board is heated, and a portion of the flux in the solder paste distributed on the circuit board vaporizes. The temperature of the peak zone 103 is higher than that of the preheating zone 101, and the solder paste completely melts in the peak zone 103. Peak region 103 is also the area where higher-temperature VOCs (such as rosin and resin in flux) will vaporize.

[0021] A cooling device (not shown in the figure) is provided in the cooling zone 105. In the embodiment shown in FIG1A, the cooling zone 105 includes four sub-cooling zones C01-C04, which are also arranged sequentially according to their numbers. After the circuit board is fed into the cooling zone 105 from the peak zone 103, the solder paste is cooled and solidified on the soldering area of ​​the circuit board, thereby connecting the electronic components to the circuit board. It is worth noting that the number of sub-regions in the preheating zone 101, peak zone 103 and cooling zone 105 of the reflow oven can be varied according to the product to be soldered and different soldering processes, and is not limited to the embodiments shown in FIG1A and FIG1B.

[0022] A barrier exhaust zone 109 is provided in the connection area between the side peak zone Z12 of the peak zone 103 and the sub-cooling zone C01 of the cooling zone 105. The barrier exhaust zone 109 can extract or discharge gas from the furnace 112. After cooling and filtration, the gas extracted from the barrier exhaust zone 109 can be transported back to the lower-temperature preheating zone 101 in the furnace 112, thereby preventing or reducing the entry of gas containing volatile pollutants from the peak zone 103 into the cooling zone 105. In addition, by extracting or discharging gas from the furnace 112, the barrier exhaust zone 109 can also be used as a heat insulation zone to isolate the high-temperature peak zone 103 and the low-temperature cooling zone 105. In this embodiment, the reflow oven 110 is also equipped with an exhaust device (not shown in the figure) for discharging gas containing volatile pollutants from the furnace 112. The exhaust system is typically connected to a high-temperature area of ​​the reflow oven 110, such as the peak zone 103 or the barrier exhaust zone 109.

[0023] The reflow oven 110 of this invention uses a working gas mainly composed of nitrogen, and also includes oxygen with a content controlled within a certain range. The reflow oven 110 also includes gas barrier zones 108 located at the left and right ends of the furnace chamber 112, respectively. The gas barrier zones 108 are used to supply nitrogen towards the furnace chamber 112 to form a nitrogen curtain, which prevents air from the external environment from entering the furnace chamber 112. When the reflow oven 110 is processing circuit boards, the exhaust device remains operational to maintain the cleanliness of the gas in the furnace chamber 112. During this process, clean nitrogen and / or air must be continuously supplied to the furnace chamber 112 to maintain the required working atmosphere.

[0024] The reflow oven 110 of this invention is also equipped with a gas control system 100, which is used to adjust the oxygen concentration in the furnace 112 by adjusting the flow rate of nitrogen and / or air input into the furnace 112, so that the oxygen concentration reaches the level required by a specific welding process in the reflow oven.

[0025] Referring again to Figures 1A and 1B, the gas control system 100 includes an oxygen detection device 120, valve devices 133 (i.e., the third valve device 133) and 134 (i.e., the fourth valve device 134), and a controller 122. The oxygen detection device 120 is in contact with the gas in the furnace 112 and is used to detect the oxygen concentration in the furnace 112. Specifically, the oxygen detection device 120 is used to detect the oxygen concentration in the peak region 103 of the furnace 112. As an example, the oxygen detection device 120 is configured to detect the oxygen concentration in the middle sub-peak region Z11. The oxygen detection device 120 is configured to provide an oxygen concentration signal to the controller 122, the oxygen concentration signal reflecting the actual detected value Dv of the oxygen concentration.

[0026] Corresponding to the oxygen concentration requirements of a specific welding process, this invention pre-sets a specific oxygen concentration preset value Tv and stores it in the controller 122. The controller 122 can identify the preset value Tv and obtain the adjustment range Rvmin-Rvmax near the preset value Tv, and compare the actual detected value Dv reflected by the oxygen concentration signal generated by the oxygen detection device 120 with the adjustment range Rvmin-Rvmax. If the actual detected value Dv is greater than the maximum value Rvmax of the adjustment range Rvmin-Rvmax, it indicates that the actual oxygen concentration is too high and the actual nitrogen concentration is too low; if the actual detected value Dv is less than the minimum value Rvmin of the adjustment range Rvmin-Rvmax, it indicates that the actual oxygen concentration is too low and the actual nitrogen concentration is too high.

[0027] The third valve device 133 and the fourth valve device 134 are used to controllably connect the nitrogen source 140 (i.e., the working gas source 140) to the preheating zone 101 and the cooling zone 105 of the furnace 112, respectively, so as to input nitrogen into the furnace 112. In this embodiment, the working gas source 140 is connected to the sub-preheating zone Z02 (i.e., the sub-preheating zone second farthest from the peak zone 103) through the third valve device 133. And the working gas source 140 is connected to the sub-cooling zone C03 (i.e., the sub-cooling zone second farthest from the peak zone 103) through the fourth valve device 134. The controller 122 controls the opening degree V3 of the third valve device 133 to remain constant during the operation of the reflow oven 110, for example, the opening degree of the third valve device 133 is maintained at 10%. Furthermore, controller 122 controls the opening degree V4 of the fourth valve device 134 according to the preset oxygen concentration value Tv. For example, when the preset oxygen concentration is between 300 and 500 ppm, the opening degree V4 of the fourth valve device 134 can be set to 70%. The valve opening degree represents the degree to which the valve device is open, ranging from 0 to 100%. For example, an opening degree of 0 indicates that the valve is closed, and an opening degree of 100% indicates that it is fully open. Through the third valve device 133 and the fourth valve device 134, the oxygen concentration in the furnace 112 can be maintained approximately within a certain range near the preset oxygen concentration value Tv.

[0028] After nitrogen is introduced into the sub-preheating zone Z02 of the furnace 112 through the third valve device 133, a portion of the nitrogen flows out of the furnace 112 towards the sub-preheating zone Z01 near the furnace inlet to prevent some air from entering the furnace 112, while the other portion of the nitrogen flows towards the peak zone 103 to participate in the gas circulation inside the furnace 112. Similarly, after nitrogen is introduced into the sub-cooling zone CO3 of the furnace 112 through the fourth valve device 134, a portion of the nitrogen flows out of the furnace 112 towards the sub-cooling zone CO4 near the furnace outlet to prevent some air from entering the furnace 112, while the other portion of the nitrogen flows towards the sub-cooling zone CO1 to participate in the gas circulation inside the furnace 112.

[0029] Because the gas extracted from the exhaust zone 109 during the welding process also returns to the preheating zone 101 of the furnace 112, the gas concentration inside the furnace 112 can achieve a roughly dynamic stability. Therefore, the opening degree V3 of the third valve device 133 can remain unchanged during the operation of the reflow oven 110, and the oxygen concentration inside the furnace 112 can be roughly satisfied by setting the opening degree V4 of the fourth valve device 134 according to the preset oxygen concentration value Tv. Generally, the opening degree V3 of the third valve device 133 is smaller than the opening degree V4 of the fourth valve device 134.

[0030] As still shown in Figures 1A and 1B, the gas control system 100 further includes valve device 131 (i.e., first valve device 131) and valve device 132 (i.e., second valve device 132). The first valve device 131 and the second valve device 132 are respectively used to controllably connect the working gas source 140 and the air source 150 to the peak region 103 of the furnace 112, so as to input nitrogen and / or air into the peak region 103 of the furnace 112. The controller 122 is used to adjust the opening degree V1 of the first valve device 131 and / or the opening degree V2 of the second valve device 132 in real time according to the preset value Tv of the oxygen concentration and the detected value Dv of the oxygen concentration, so as to adjust the flow rate of nitrogen and / or air input into the furnace 112, thereby enabling the oxygen concentration in the peak region 103 of the furnace 112 to be accurately controlled near the preset value Tv, for example, within the adjustment range Rvmin-Rvmax.

[0031] As an example, the first valve device 131 and the second valve device 132 are configured to allow nitrogen and / or air to first pass through a common mixing conduit 135 before being separately introduced into the side peak regions Z10 and Z12. In this embodiment, the mixing conduit 135 has a first inlet 136, a second inlet 137, a first outlet 126, and a second outlet 127, wherein the working gas source 140 is in fluid communication with the first inlet 136 through the first valve device 131, and the air source 150 is in fluid communication with the second inlet 137 through the second valve device 132. The first outlet 126 is in fluid communication with the side peak region Z10, and the second outlet 127 is in fluid communication with the side peak region Z12. Thus, nitrogen and / or air can be introduced into the mixing conduit 135 through the first valve device 131 and / or the second valve device 132, mixed in the mixing conduit 135, and then separately introduced into the side peak regions Z10 and Z12. The term "and / or" as used above means that when the opening degrees of both the first valve device 131 and the second valve device 132 are not zero, nitrogen and air can be mixed through the mixing pipe 135 before being separately introduced into different sub-peak zones in the furnace. When the opening degree of either the first valve device 131 or the second valve device 132 is zero, the gas control system 100 only introduces either nitrogen or air into the peak zone 103, so that nitrogen or air first passes through the mixing pipe 135 before being separately introduced into different sub-peak zones in the furnace.

[0032] During the process of conveying the circuit board into or out of the furnace 112 by the conveyor 118, a relatively small amount of ambient air inevitably enters or leaves the furnace 112 along with the conveyor and the circuit board. Therefore, the working gas in the furnace 112 always contains an varying amount of oxygen. Different soldering processes have different requirements for the oxygen concentration level in the furnace 112, typically ranging from 0 to 5000 PPM (parts per million). Furthermore, since the peak zone 103 in the reflow oven 110 has the highest temperature, it is also the area that has a significant impact on soldering quality during the soldering process. Therefore, it is desirable that the oxygen concentration in the furnace 112, especially the oxygen concentration in the peak zone 103, be maintained near, or within, the value required for a specific soldering process.

[0033] In some existing gas control systems, the oxygen concentration in the furnace is generally controlled by continuously supplying nitrogen into the furnace. When the oxygen concentration in the furnace is high, nitrogen can be introduced into the furnace to reduce the oxygen concentration. However, when the oxygen concentration in the furnace is low, it is necessary to wait for the air trapped in the conveying device and circuit board to increase the oxygen concentration. This not only results in untimely adjustment but also makes it difficult to control the oxygen content, affecting the soldering quality of the circuit board.

[0034] In the gas control system of the application, based on the detected oxygen concentration, the oxygen concentration in the peak zone 103 is adjusted in real time by directly inputting nitrogen and / or air into the peak zone 103, so that the oxygen concentration can be maintained near the required preset value Tv, for example, within the adjustment range Rvmin-Rvmax. For example, when the detected oxygen concentration Dv is greater than Rvmax, nitrogen can be input into the peak zone 103; when the detected oxygen concentration Dv is less than Rvmin, air is input into the peak zone 103; and when the detected oxygen concentration is within the adjustment range Rvmin-Rvmax, both nitrogen and air are input into the peak zone 103 simultaneously. Thus, the oxygen concentration in the peak zone 103 of the furnace 112 can be maintained more accurately near the required preset value Tv.

[0035] In this embodiment, the first valve device 131, the second valve device 132, the third valve device 133 and the fourth valve device 134 are all flow control valves, and the first valve device 131 and the second valve device 132 have higher precision requirements.

[0036] Figure 2 is a simplified schematic diagram of an embodiment of the controller 122 in Figure 1. The controller 122 includes a bus 202, a processor 204, an input interface 206, an output interface 208, and a memory 214 having a control program 216. The processor 204, the input interface 206, the output interface 208, and the memory 214 are communicatively connected through the bus 202, enabling the processor 204 to control the operation of the input interface 206, the output interface 208, and the memory 214. The memory 214 is used to store programs, instructions, and data. The processor 204 reads programs, instructions, and data from the memory 214 and can write data to the memory 214.

[0037] Input interface 206 receives signals and data via connection 218, such as oxygen concentration signals emitted by oxygen detection device 120 and various manually input parameters. Output interface 208 sends signals and data via connection 219, such as sending control signals to adjust the opening of various valve devices. Memory 214 stores control program 216 and preset values ​​and adjustment ranges of oxygen concentration. Various parameters can be preset during the manufacturing process or set manually or by importing data during use. Processor 204 obtains various signals, data, programs, and instructions from input interface 206 and memory 214, processes them accordingly, and outputs them through output interface 208.

[0038] Figure 3 illustrates the gas control method for the reflow oven shown in Figure 1A. As shown in Figure 3, the reflow oven 110 is configured to perform the following steps:

[0039] Step 341: Reflow oven 110 starts running, then execute steps 342 and 343.

[0040] Step 342: Receive the preset value Tv of oxygen concentration set according to the specific welding process requirements and the detected value Dv of oxygen concentration actually detected by the oxygen detection device 120, and then execute steps 344 and 345.

[0041] Step 343: Set the opening degree V3 of the third valve device 134.

[0042] Step 344: Determine the adjustment range Rvmin-Rvmax, store the adjustment range in the memory 214 of the controller 122, and then execute step 346.

[0043] Step 345: Set the opening degree V4 of the fourth valve device 134.

[0044] Step 346: Compare the probe value Dv with the adjustment range Rvmin-Rvmax. When the probe value Dv < Rvmin, proceed to step 347. When the probe value Dv > Rvmax, proceed to step 349. When Rvmin ≦ probe value Dv ≦ Rvmax, proceed to step 348.

[0045] Step 347: Increase the opening degree V1 of the first valve device 131, and then return to step 346.

[0046] Step 348: Simultaneously increase the opening degree V1 of the first valve device 131 and the opening degree V2 of the second valve device 132, and then return to step 346.

[0047] Step 349: Increase the opening degree V2 of the second valve device 132, and then return to step 346.

[0048] Thus, the gas control system 100 of this invention can adjust the oxygen concentration in the peak zone 103 of the reflow oven furnace 112 in real time and dynamically. In steps 347, 348 and 349, the specific values ​​of the opening degree of the first valve device 131 and the second valve device 132 are calculated according to a certain algorithm. As an example, the algorithm can be a PID algorithm (Proportion Integral Differential algorithm).

[0049] The gas control system and reflow oven in this case first perform coarse adjustment of the gas in the reflow oven chamber through the third and fourth valve devices, so that the oxygen concentration in the chamber is approximately near the preset value. Then, the oxygen concentration in the peak zone of the chamber is precisely adjusted through the first and second valve devices. In this way, even though the amount of oxygen in the air entering the chamber is variable, it will not affect the oxygen concentration in the peak zone, thereby consistently improving the soldering quality of the circuit board.

[0050] This specification uses examples to disclose the present invention, one or more of which are illustrated in the accompanying drawings. Each example is provided for the purpose of explaining the present invention and not for limiting it. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the scope or spirit thereof. For example, a feature illustrated or described as part of one embodiment may be used with another embodiment to obtain a further embodiment. Therefore, it is intended that the present invention cover modifications and variations made within the scope of the appended claims and their equivalents. [Simplified Explanation of the Diagram]

[0014] Figure 1A is a schematic diagram of a reflow oven according to an embodiment of the present invention;

[0015] Figure 1B is a gas flow diagram in the gas control system of the reflow oven shown in Figure 1A;

[0016] Figure 2 is a schematic diagram of the control device in Figure 1A;

[0017] Figure 3 is a schematic diagram of the steps of the gas control method for the reflow oven shown in Figure 1A. [Biomaterial Storage]

[0052] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A gas control system for a reflow oven, the reflow oven (110) having a gas in its furnace chamber (112) comprising oxygen and a working gas, the furnace chamber (112) comprising a preheating zone (101), a peak zone (103), and a cooling zone (105), wherein the peak zone (103) comprises three sub-peak zones (Z10, Z11, Z12), the three sub-peak zones (Z10, Z11, Z12) comprising a central sub-peak zone (Z11) located in the middle and two side sub-peak zones (Z10, Z12) located on both sides of the central sub-peak zone (Z11), and characterized in that the gas control system (100) comprises: An oxygen detection device (120) configured to detect the oxygen concentration in the central sub-peak region (Z11); a first valve device (131) configured to controllably connect a working gas source (140) to the peak region (103) of the furnace (112); and a second valve device (132) configured to controllably connect an air source (150) to the peak region (103) of the furnace (112). A controller (122) is communicatively connected to the oxygen detection device (120), the first valve device (131), and the second valve device (132). The controller (122) is configured to control the opening of at least one of the first valve device (131) and the second valve device (132) when the oxygen concentration detected by the oxygen detection device (120) does not meet a preset value, so as to adjust the flow rate of at least one of the working gas and air input into the peak region (103) of the furnace (112) to make the oxygen concentration in the peak region (103) meet the preset value; and to mix The mixing pipe (135) includes a first inlet (136), a second inlet (137) and at least one outlet (126, 127). The working gas source (140) is in fluid communication with the first inlet (136) through the first valve device (131), and the air source (150) is in fluid communication with the second inlet (137) through the second valve device (132). The at least one outlet (126, 127) includes two outlets (126, 127), and the two outlets (126, 127) are in fluid communication with the two side sub-peak regions (Z10, Z12) respectively.

2. The gas control system according to claim 1, characterized in that it further comprises: A third valve device (133) is configured to fluidly communicate the working gas source (140) with the preheating zone (101) of the furnace (112); the opening of the third valve device (133) remains constant during the operation of the reflow oven (110).

3. The gas control system according to request item 2, wherein: The preheating zone (101) includes several sub-preheating zones (Z01, Z02...Z09), and the working gas source (140) is controllably connected to a sub-preheating zone (Z02) that is second furthest from the peak zone (103) via the third valve device (133).

4. The gas control system according to claim 2, characterized in that it further comprises: A fourth valve device (134) is configured to fluidly connect the working gas source (140) to the cooling zone (134) of the furnace (112); the opening degree of the fourth valve device (105) is determined according to the preset value.

5. The gas control system according to request item 4, wherein: The cooling zone (105) includes several sub-cooling zones (C01, C02...C04), and the working gas source (140) is controllably connected to a sub-cooling zone (C03) that is second furthest from the peak zone (103) via the fourth valve device (134).

6. The gas control system according to any one of claims 1 to 5, further comprising: A barrier exhaust zone (109) is located between the peak zone (103) and the cooling zone (105), wherein the barrier exhaust zone (109) extracts or discharges gas from the furnace.

7. The gas control system according to claim 6, wherein the gas extracted or discharged from the furnace is delivered into the preheating zone (101).

8. The gas control system according to request item 1, wherein: The controller (122) is configured to: determine the adjustment range based on a preset value of the oxygen concentration; when the oxygen concentration detected by the oxygen detection device (120) is greater than the maximum value of the adjustment range, increase the opening of the first valve device (131) to increase the flow rate of the working gas input into the peak region (103) of the furnace (112) so that the oxygen concentration reaches the adjustment range; when the oxygen concentration detected by the oxygen detection device (120) is less than the minimum value of the adjustment range, increase the opening of the second valve device (132) to increase the flow rate of oxygen input into the peak region (103) of the furnace (112) so that the oxygen concentration reaches the adjustment range; when the oxygen concentration detected by the oxygen detection device (120) is within the adjustment range, adjust the opening of the first valve device (131) and the second valve device (132) so that the oxygen concentration in the peak region (103) meets the preset value.

9. The gas control system according to request item 4, wherein: The first valve device (131), the second valve device (132), the third valve device (133) and the fourth valve device (134) are flow control valves.

10. A reflow oven, characterized in that it comprises: A furnace (112) comprising a preheating zone (101), a peak zone (103), and a cooling zone (105), the furnace (112) containing a gas including oxygen and a working gas, wherein the peak zone (103) comprises three sub-peak zones (Z10, Z11, Z12), the three sub-peak zones (Z10, Z11, Z12) comprising a central sub-peak zone (Z11) located in the middle and two side sub-peak zones (Z10, Z12) located on both sides of the central sub-peak zone (Z11); and a gas control system (100) as claimed in any one of claims 1-9.

Images