Control method for reflow soldering system and reflow soldering system

Abstract

The present invention provides a control method for a reflow soldering system and a reflow soldering system. The control method of the present invention comprises the steps of: providing a circuit board that has been processed by a reflow soldering process and is installed with a flattening tool; obtaining the pre-heating temperature of the circuit board; when the pre-heating temperature is within a predetermined range, placing the circuit board in a temperature control device and continuously heating the circuit board for a first predetermined time, so that the circuit board reaches a predetermined temperature, the predetermined temperature is greater than the glass transition temperature of the dielectric layer of the circuit board, and is less than the melting point of the solder used in the reflow soldering process; after the circuit board reaches the predetermined temperature, controlling the temperature control device to continuously cool the circuit board; after cooling the circuit board for a second predetermined time, stopping cooling the circuit board. The above technical solution is intended to solve the problem of easy warping of circuit boards after reflow soldering in the prior art.

Description

Technical Field

[0001] The invention relates to the field of integrated circuit production, and specifically provides a control method for a reflow soldering system and a reflow soldering system. Background Art

[0002] As electronic components become smaller, thinner, smarter, and more multifunctional, the performance and integration of chips (ICs) continue to improve, and the wiring of circuit boards is becoming more and more dense and asymmetric. The existing circuit board manufacturing process has gradually failed to meet product design requirements, and circuit board warping is often caused by substrate design, such as asymmetric patterns of each layer. In the asymmetric circuit board manufacturing process, the residual stress of the circuit board cannot be eliminated when the circuit board is left at room temperature after reflow soldering, and the circuit board will warp after shaping. In mild cases, it may cause the post-process transmission mechanism to be unable to operate, and in severe cases, it may be directly scrapped at the station.

[0003] Therefore, this field needs a new technical solution to solve the above problems. Summary of the invention

[0004] In order to solve the problem of circuit boards being easily warped after reflow soldering in the prior art, the present invention provides a control method for a reflow soldering system. The control method of the present invention comprises the steps of: providing a circuit board that has been processed by a reflow soldering process and is installed with a flattening tool; obtaining the pre-heating temperature of the circuit board; when the pre-heating temperature is within a predetermined range, placing the circuit board in a temperature control device and continuously heating the circuit board for a first predetermined time, so that the circuit board reaches a predetermined temperature, the predetermined temperature is greater than the glass transition temperature of the dielectric layer of the circuit board and is less than the melting point of the solder used in the reflow soldering process; after the circuit board reaches the predetermined temperature, controlling the temperature control device to continuously cool the circuit board; after cooling the circuit board for a second predetermined time, stopping cooling the circuit board.

[0005] The control method of the present invention is applicable to a circuit board that has been subjected to reflow soldering. Therefore, when the present invention is started, a circuit board that has been subjected to a reflow soldering process and is equipped with a flattening tool is first provided. A flattening tool is arranged on the circuit board so that when the circuit board is heated by a temperature control device and its dielectric layer is transformed from a glass state to a highly elastic state, it can be flattened under the action of the flattening tool. The pre-heating temperature of the circuit board is obtained, and when the pre-heating temperature is within a predetermined range, the circuit board is heated by the temperature control device. Through the above configuration, it is prevented that a circuit board with an excessively high temperature enters the temperature control device and reaches a predetermined temperature in a relatively short time, resulting in insufficient stress release; and it is prevented that a circuit board with an excessively low temperature enters the temperature control device and the heating time is too long, affecting production efficiency. After heating the circuit board for the first predetermined time, the circuit board reaches a predetermined temperature, and the temperature control device is controlled to cool the circuit board. Among them, the predetermined temperature is greater than the glass transition temperature of the dielectric layer of the circuit board and less than the melting point of the solder used in the reflow soldering process. Through the above configuration, when the predetermined temperature is reached, the dielectric layer of the circuit board is transformed from a glass state to a highly elastic state, and at this time, the flattening tool can flatten the warped circuit board. At the same time, the predetermined temperature will not cause the solder to melt, thus preventing the assembled electronic components from being poorly soldered or falling off during the heating process. After cooling the circuit board for the second predetermined time, the cooling of the circuit board is stopped. By setting the second predetermined time, the circuit board heated to the predetermined temperature slowly lowers its temperature again, and the residual stress in the circuit board is fully released. The circuit board is kept flat from the semi-solid state to the solid state under the action of the flattening tool, thus solving the problem of easy warping after reflow soldering.

[0006] In the preferred technical scheme of the control method for the reflow soldering system, the reflow soldering system includes a reflow soldering furnace and a material transfer assembly, and the step of "providing a circuit board that has been processed by the reflow soldering process and is installed with a flattening fixture" includes: providing a circuit board to be soldered, and installing the flattening fixture on the circuit board to be soldered; using the reflow soldering furnace to solder the circuit board to be soldered; after soldering is completed, using the material transfer assembly to transfer the soldered circuit board and the flattening fixture to the temperature control device. Through the above-mentioned setting, installing the flattening fixture before reflow soldering can ensure that the electronic components will not be separated from the circuit board during reflow soldering, ensuring the soldering effect, and it does not need to be disassembled in the subsequent process of suppressing warping, which plays a role in providing flattening pressure, simplifies the process flow, and improves the production efficiency of the circuit board.

[0007] In the preferred technical solution of the control method for the reflow soldering system, the temperature control device is the reflow furnace, which includes an inlet and an outlet. The circuit board to be soldered enters the reflow furnace from the inlet for soldering, and exits the reflow furnace from the outlet after soldering is completed. The step of "using the material transfer component to transfer the soldered circuit board installed with the flattening tool to the temperature control device" is: using the material transfer component to transfer the soldered circuit board from the outlet to the inlet. Through the above-mentioned setting, there is no need to set up an additional temperature control device, and the process of suppressing the warping of the circuit board can be completed by using the reflow soldering furnace in the reflow soldering system, which greatly reduces the use cost of the control method of the present invention, so that it can be directly applied to the existing reflow soldering system.

[0008] In the preferred technical scheme of the control method for the reflow soldering system, the control method further includes: after stopping cooling the circuit board, withdrawing the circuit board from the reflow soldering furnace from the discharge port; removing the leveling tool from the circuit board, and using the material transfer assembly to transfer the removed leveling tool to the inlet port for installation on the circuit board to be soldered. Through the above configuration, the leveling tool removed from the stress-released circuit board and the soldered circuit board can be transferred from the discharge port to the inlet port by the material transfer assembly, forming a whole process of entering the furnace, transferring the circuit board by the material transfer assembly, re-entering the furnace, and then transferring the leveling tool by the material transfer assembly to solder and suppress warping. This process can be completely completed by relying on the original reflow soldering system, which greatly reduces the use cost of the control method of the present invention.

[0009] In the preferred technical scheme of the control method for the reflow soldering system, the temperature control device includes a temperature control chamber for accommodating the circuit board, the temperature control chamber includes a transmission mechanism and a heating zone and a cooling zone arranged in sequence along the transportation direction of the transmission mechanism, the transmission mechanism is configured to transport the circuit board at a uniform speed, the step of "continuously heating the circuit board" is to use the transmission mechanism to transport the circuit board through the heating zone, the first predetermined time is the time for the transmission mechanism to transport the circuit board through the heating zone; the step of "continuously cooling the circuit board" is to use the transmission mechanism to transport the circuit board through the cooling zone, and the second predetermined time is the time for the transmission mechanism to transport the circuit board through the cooling zone. Through the above-mentioned settings, after setting the transportation speed of the transmission mechanism and the temperature in the temperature control chamber, the operation of suppressing the warping of the circuit board can be carried out in batches.

[0010] In the preferred technical solution of the control method for the reflow soldering system, the heating zone includes multiple sub-zones, the temperatures of the multiple sub-zones are kept constant, and in the direction of the circuit board being transported by the transmission mechanism, the temperature of the downstream sub-zone is higher than the temperature of the upstream sub-zone. Through the above arrangement, the multiple sub-zones heat the circuit board in stages, so that the circuit board can maintain a relatively stable heating rate and fully release stress during the heating process.

[0011] In the preferred technical solution of the control method for the reflow soldering system, the transmission speed of the transmission mechanism is configured to keep the heating rate of the circuit board in the heating zone between 0.5°C / s and 1.5°C / s. Through the above setting, within the heating rate range, the dielectric layer of the circuit board can fully release stress.

[0012] In the preferred technical solution of the control method for the reflow soldering system, the predetermined range is 30° C.-50° C. Through the above setting, the circuit board within the temperature range can be heated to the predetermined temperature at a relatively stable heating rate after entering the temperature control chamber, thereby avoiding the circuit board temperature being too low and causing the operation time to be too long.

[0013] In order to solve the problem of circuit boards being prone to warping after reflow soldering in the prior art, the present invention also provides a reflow soldering system. The reflow soldering system of the present invention is used to execute the control method for the reflow soldering system in the above-mentioned preferred technical solution, and the reflow soldering system includes a temperature control device. After the temperature control device heats the circuit board for a first predetermined time, when the circuit board reaches a predetermined temperature, the temperature control device cools the circuit board, and the predetermined temperature is greater than the glass transition temperature of the dielectric layer of the circuit board and less than the melting point of the solder used in the reflow soldering process. Through the above-mentioned setting, when the predetermined temperature is reached, the dielectric layer of the circuit board is transformed from a glassy state to a highly elastic state, and the warped circuit board can be flattened at this time. At the same time, the predetermined temperature will not cause the solder to melt, avoiding the assembled electronic components from being poorly soldered or falling off during the heating process. The residual stress in the circuit board is fully released, solving the problem of easy warping after reflow soldering.

[0014] In the preferred technical solution of the above reflow soldering system, the temperature control device is a reflow furnace, the reflow furnace includes an inlet and an outlet, and the reflow soldering system also includes a material moving component, the material moving component can transfer the soldered circuit board from the outlet to the inlet, or transfer the leveling tool removed from the circuit board at the outlet to the inlet. Through the above arrangement, the leveling tool removed from the stress-released circuit board and the soldered circuit board can be transferred from the outlet to the inlet by the material moving component, forming a cycle of entering the furnace, transferring the circuit board by the material moving component, re-entering the furnace, and then transferring the soldering of the leveling tool by the material moving component and suppressing warping. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0016] Figure 1 It is a schematic flow chart of a control method for a reflow soldering system according to the present invention;

[0017] Figure 2 is the first part of the flowchart of an embodiment of a control method for a reflow soldering system of the present invention;

[0018] Figure 3 This is the second part of the flowchart of the embodiment of the control method for a reflow soldering system of the present invention. DETAILED DESCRIPTION

[0019] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0020] It should be noted that, in the description of the present invention, the terms “first” and “second” are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0021] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In the prior art, reflow soldering technology is usually used to solder the mounted components on the circuit board. Since the melting point of the solder used in the prior art is usually higher than the glass transition temperature of the dielectric layer material of the circuit board, when the solder melts and fully contacts the mounted components and the circuit board on its opposite sides, the dielectric layer in the circuit board has been transformed into a highly elastic state and has undergone a large deformation. In the later stage of reflow soldering, the temperature needs to drop relatively quickly (for example, the cooling rate is usually 6-10°C) to ensure that a stable metal structure is formed inside the solder during the solidification process and that there are fewer defects in the appearance.

[0023] However, during the rapid temperature drop, due to the asymmetry of the circuits stacked on both sides of the circuit board, the deformation of the dielectric layer caused by heat cannot be completely restored, that is, the stress inside the circuit board cannot be completely released, which will eventually cause the circuit board to warp after returning to room temperature.

[0024] In order to solve the problem of easy warping of circuit boards after reflow soldering in the prior art, the present invention provides a control method for a reflow soldering system. The control method of the present invention comprises the steps of: providing a circuit board that has been processed by a reflow soldering process and is installed with a flattening tool; obtaining the pre-heating temperature of the circuit board; when the pre-heating temperature is within a predetermined range, placing the circuit board in a temperature control device and continuously heating the circuit board for a first predetermined time, so that the circuit board reaches a predetermined temperature, the predetermined temperature is greater than the glass transition temperature of the dielectric layer of the circuit board and is less than the melting point of the solder used in the reflow soldering process; after the circuit board reaches the predetermined temperature, controlling the temperature control device to continuously cool the circuit board; after cooling the circuit board for a second predetermined time, stopping cooling the circuit board.

[0025] Figure 1 1 is a flow chart of the control method for the reflow soldering system of the present invention. Figure 1 The main technical means of the control method of the present invention to solve the problem that the circuit board is prone to warping after reflow soldering is described.

[0026] like Figure 1 As shown, after the control method of the present invention starts, step S10 is first performed, that is, a circuit board that has been processed by the reflow soldering process and is installed with a flattening tool is provided. The flattening tool can provide a pressing force that makes the circuit board tend to be flat, so as to play a role in the subsequent steps. The circuit board includes but is not limited to an IC carrier, a PCB substrate, etc. Then step S20 is performed, that is, the pre-heating temperature of the circuit board is obtained. When the circuit board is under suitable temperature conditions, the reflow soldering system using the control method can fully release the residual stress in the warped circuit board and ensure high production efficiency. Then enter step S30, that is, when the pre-heating temperature is within a predetermined range, the circuit board is placed in a temperature control device and the circuit board is continuously heated for a first predetermined time, so that the circuit board reaches a predetermined temperature. Among them, the predetermined temperature is greater than the glass transition temperature of the dielectric layer of the circuit board and is less than the melting point of the solder used in the reflow soldering process. Through the above-mentioned setting, when the predetermined temperature is reached, the dielectric layer of the circuit board is converted from a glass state to a highly elastic state, and at this time the flattening tool can flatten the warped circuit board. At the same time, the predetermined temperature will not cause the solder to melt, avoiding the assembled electronic components from being poorly soldered or falling off during the heating process. Then, step S40 is executed, that is, after the circuit board reaches the predetermined temperature, the temperature control device is controlled to continuously cool the circuit board. Finally, step S50 is executed, that is, after the circuit board is cooled for the second predetermined time, the cooling of the circuit board is stopped. By controlling the time, it is ensured that the circuit board is fully released from stress during the cooling process. At this point, the residual stress in the circuit board is fully released, and the circuit board is kept flat under the action of the flattening tool, solving the problem of easy warping after reflow soldering.

[0027] Figure 2 is the first part of the flowchart of an embodiment of a control method for a reflow soldering system of the present invention; Figure 3 This is the second part of the flowchart of the embodiment of the control method for the reflow soldering system of the present invention. Figure 2 and Figure 3 The execution flow of the control method of the present invention is described in detail.

[0028] In one or more embodiments, the reflow soldering process is completed in a reflow soldering system, which includes a reflow soldering furnace and a material transfer assembly. Figure 2 As shown, after the control method starts, it first enters step S11, that is, providing a circuit board to be soldered, and installing a flattening jig on the circuit board to be soldered. The circuit board to be soldered is affixed with electronic components to be soldered, and the solder paste can be heated and melted in a reflow furnace to make the electronic components precisely adhere to the circuit board and electrically connected. The flattening jig can be an aluminum alloy magnetic jig, or it can be configured as other suitable jigs. The aluminum alloy magnetic jig can press the electronic components onto the circuit board to prevent the electronic components from falling off when the solder paste does not play a bonding role; it can also provide a pressing force to make the circuit board tend to be flat. Then enter step S11, that is, use the reflow furnace to solder the circuit board to be soldered.

[0029] After the welding is completed, the circuit board can exit the reflow furnace, and the material transfer assembly can be used to transfer the circuit board with the welding completed and the flattening fixture installed to the temperature control device, so as to perform the stress release step in the temperature control device. In one or more embodiments, the temperature control device is a reflow furnace, and the reflow furnace includes an inlet and an outlet. After the welding is completed, the material transfer assembly can be used to transfer the circuit board with the welding completed and the flattening fixture installed from the outlet to the inlet (i.e., step S13). Exemplarily, a heating unit and a cooling unit are provided in the reflow furnace, and the heating unit can be used to melt the solder paste, and can also be used to heat the circuit board to change the physical form of the dielectric layer of the circuit board. The cooling unit can be used to cool the circuit board to a suitable temperature for shaping. In addition, the reflow furnace also includes a tunnel-type reflow cavity, and multiple circuit boards can be simultaneously processed in the reflow cavity to improve the warpage, which is also convenient for controlling the temperature rise / fall slope of the circuit board to ensure that the circuit board is fully released from stress. In an alternative embodiment, the temperature control device can also be other devices that exist independently of the reflow furnace for reflow welding, which are specifically used to improve the warpage of the circuit board.

[0030] Then, step S20 is performed, i.e., obtaining the temperature of the circuit board before heating to ensure that the residual stress in the circuit board is fully released and the production efficiency of the circuit board is improved. Then, step S31 is performed, i.e., determining whether the temperature before heating is within a predetermined range. In one or more embodiments, the predetermined range is configured to be 30°C-50°C. Alternatively, the predetermined range can also be set to other suitable values ​​according to actual needs. If the judgment result of step S31 is no, it means that the temperature of the circuit board before heating is not suitable for directly entering the reflow furnace to improve the warpage, and the circuit board should be pre-treated (i.e., step S311). If the temperature before heating is higher than the predetermined range, it can be placed in a room temperature environment to cool for a period of time before being sent to the reflow furnace; if the temperature before heating is lower than the predetermined range, it can be quickly heated to the predetermined range in a high temperature environment and then sent to the reflow furnace. If the judgment result of step S31 is yes, it means that the current temperature of the circuit board is suitable for being sent to the reflow furnace to improve the warpage, then step S312 is performed, i.e., the circuit board is placed in the reflow furnace and continuously heated for the first predetermined time to make the circuit board reach the predetermined temperature. Alternatively, the reflow furnace can be other suitable temperature control devices.

[0031] In one or more embodiments, the temperature control device (e.g., a reflow furnace) includes a temperature control chamber for accommodating a circuit board, and the temperature control chamber includes a conveying mechanism and a heating zone and a cooling zone arranged in sequence along the conveying direction of the conveying mechanism. The conveying mechanism is configured to transport the circuit board at a uniform speed, and the circuit board placed in the temperature control device is placed on the conveying mechanism, and driven by the conveying mechanism, passes through the heating zone and the cooling zone in sequence to complete the heating and cooling operations. Exemplarily, when the circuit board is fed into the reflow furnace from the feed port, it is transported to the discharge port by the conveying mechanism.

[0032] Further, the heating zone may also include a plurality of sub-zones, for example, 5 sub-zones. The temperature of each sub-zone is kept constant, and in the direction of the conveying mechanism transporting the circuit board, the temperature of the downstream sub-zone is higher than the temperature of the upstream sub-zone. Exemplarily, the temperature of the first sub-zone is set to approximately 60°C, the temperature of the second sub-zone is set to approximately 100°C, the temperature of the third sub-zone is set to approximately 140°C, the temperature of the fourth sub-zone is set to approximately 180°C, and the temperature of the fifth sub-zone is set to approximately 200°C. The circuit board passing through the above 5 sub-zones can be heated to a predetermined temperature at a stable heating rate, so as to fully release stress during the heating process and avoid excessive heating in some time periods. In alternative embodiments, other suitable structures may also be set in the temperature control chamber to ensure stable heating of the circuit board. Specifically, the heating rate is maintained between 0.5°C / s-1.5°C / s. Accordingly, the transmission speed of the conveying mechanism needs to be configured to keep the heating rate of the circuit board in the heating zone between 0.5°C / s-1.5°C / s. Those skilled in the art can understand that, after the reflow furnace is debugged according to the material characteristics of a batch of circuit boards, the heating parameters of the heating zone, the cooling parameters, the transmission speed of the transmission mechanism, the first predetermined time and the second predetermined time are maintained fixed, so as to ensure that the circuit boards with a temperature within the predetermined range can enter the reflow furnace and complete the warping suppression operation in batches.

[0033] In one or more embodiments, the first predetermined time is the time for the transmission mechanism to transport the circuit board through the heating zone. The first predetermined time is set between 2min-4min to ensure the speed of suppressing the warping of the circuit board. Alternatively, the first predetermined time can also be configured as other suitable times according to actual needs. The predetermined temperature is a temperature greater than the glass transition temperature of the dielectric layer of the circuit board and less than the melting point of the solder used in the reflow soldering process. In one or more embodiments, the dielectric layer of the circuit board usually adopts ABF, BT resin, etc., and its glass transition temperature (at this temperature, the dielectric material changes from a glass state to a highly elastic state, and in a highly elastic state, the material can be deformed under a certain external force) is roughly between 150°C and 170°C. Solder usually adopts SAC305, etc., and its melting point is about 220°C. The predetermined temperature can be set between 170°C and 200°C, and can also be configured as other suitable temperatures according to the actual material selection.

[0034] Then, step S40 is performed, that is, after the circuit board reaches the predetermined temperature, the reflow furnace is controlled to continuously cool the circuit board. The step of "continuously cooling the circuit board" is to use a conveying mechanism to transport the circuit board through the cooling zone. In one or more embodiments, the configuration of the cooling zone can be to continuously supply low-temperature gas, such as nitrogen, to the cooling zone through an airflow driving device, so that the temperature of the circuit board can be reduced to 50 degrees at a cooling rate of 3°C / s-5°C / s. If the cooling rate used in the above interval is <3°C / s, there is a risk of deterioration of the reliability of the solder ball. Furthermore, SAC305 may be converted into a three-silver-one-copper alloy, and its quality and reliability are greatly different from the original alloy. Alternatively, the cooling rate of the circuit board can also be controlled at other suitable values ​​according to actual needs. Alternatively, the cooling zone can also be set to other suitable structures, such as setting a coil evaporator. In the cooling process of the circuit board, it is first determined whether a second predetermined time has passed after the cooling of the circuit board (i.e., step S51). In one or more embodiments, the second predetermined time is the time for the conveying mechanism to transport the circuit board through the cooling zone. The second predetermined time can be set to less than 60s. Alternatively, the second predetermined time can also be configured to other appropriate time according to actual needs. If the judgment result of step S51 is yes, it means that the cooling process is sufficient for the circuit board to fully release the stress, the stress is released and the shaping is completed, and the warping of the circuit board is improved, then step S52 is executed to stop cooling the circuit board and withdraw the circuit board from the discharge port of the reflow furnace. If the judgment result of step S51 is no, it means that the cooling time is not sufficient, then return to step S40 and repeat the execution.

[0035] After the circuit board exits the reflow furnace, step S60 is performed, that is, the flattening jig is removed from the circuit board, and the removed flattening jig is transferred to the inlet by using the material transfer assembly for installation on the circuit board to be soldered. At this point, the flattening jig can be used to be installed on a new circuit board to be soldered to perform a new soldering-warpage improvement process.

[0036] In one or more embodiments, the reflow furnace further includes a nitrogen release device for controlling the oxygen content in the reflow chamber. The control method further includes: during the heating of the circuit board, maintaining the oxygen concentration in the temperature-controlled chamber below 100 ppm to prevent oxidation of the circuit board and the electronic components, solder, etc. attached thereto. Alternatively, the oxygen concentration may also be configured to other suitable values.

[0037] The present invention also provides a reflow soldering system. The reflow soldering system is used to execute the above-mentioned control method for the reflow soldering system. The reflow soldering system includes a temperature control device. After the temperature control device heats the circuit board for a first predetermined time, when the circuit board reaches a predetermined temperature, the temperature control device cools the circuit board. The predetermined temperature is greater than the glass transition temperature of the dielectric layer of the circuit board and less than the melting point of the solder used in the reflow soldering process. In one or more non-embodiments, the temperature control device is a reflow furnace. The reflow furnace includes an inlet and an outlet. The reflow soldering system also includes a material moving assembly, which can transfer the soldered circuit board from the outlet to the inlet, or transfer the flattening tool removed from the circuit board at the outlet to the inlet.

[0038] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A control method for a reflow soldering system, characterized in that: The control method comprises the steps of: Providing a circuit board that has been processed by a reflow soldering process and has a flattening fixture installed; Obtaining the pre-heating temperature of the circuit board; When the pre-heating temperature is within a predetermined range, placing the circuit board in a temperature control device and continuously heating the circuit board for a first predetermined time, so that the circuit board reaches a predetermined temperature, wherein the predetermined temperature is greater than a glass transition temperature of a dielectric layer of the circuit board and less than a melting point of a solder used in the reflow soldering process; After the circuit board reaches the predetermined temperature, controlling the temperature control device to continuously cool the circuit board; After cooling the circuit board for a second predetermined time, stopping cooling the circuit board, wherein the second predetermined time is less than 60 seconds; The reflow soldering system includes a reflow soldering furnace and a material transfer assembly, and the step of "providing a circuit board that has been processed by a reflow soldering process and is equipped with a flattening tool" includes: Providing a circuit board to be soldered, and installing the flattening tool on the circuit board to be soldered; Using the reflow furnace to solder the circuit board to be soldered; After the welding is completed, the material transfer assembly is used to transfer the circuit board after the welding is completed and the flattening tool is installed to the temperature control device; The temperature control device is the reflow furnace, which includes an inlet and an outlet. The circuit board to be welded enters the reflow furnace from the inlet for welding, and exits the reflow furnace from the outlet after welding. The step of "using the material moving component to transfer the circuit board that has been welded and installed with the leveling tool to the temperature control device" is: using the material moving component to transfer the circuit board that has been welded and installed with the leveling tool from the outlet to the inlet; The control method further includes: after stopping cooling the circuit board, withdrawing the circuit board from the reflow furnace from the discharge port; removing the flattening tool from the circuit board, and using the material transfer assembly to transfer the removed flattening tool to the inlet port for installation on the circuit board to be soldered; The temperature control device comprises a temperature control chamber for accommodating the circuit board, the temperature control chamber comprises a transmission mechanism and a heating zone and a cooling zone arranged in sequence along the transport direction of the transmission mechanism, the transmission mechanism is arranged to transport the circuit board at a uniform speed, The step of "continuously heating the circuit board" is to use the conveying mechanism to transport the circuit board through the heating zone, and the first predetermined time is the time for the conveying mechanism to transport the circuit board through the heating zone; The step of "continuously cooling the circuit board" is to use the conveying mechanism to transport the circuit board through the cooling zone, and the second predetermined time is the time for the conveying mechanism to transport the circuit board through the cooling zone; The heating zone includes a plurality of sub-zones, the temperatures of the plurality of sub-zones are kept constant, and in the direction in which the circuit board is transported by the conveying mechanism, the temperature of the downstream sub-zone is higher than the temperature of the upstream sub-zone; The transmission speed of the transmission mechanism is configured to keep the heating rate of the circuit board in the heating zone between 0.5° C. / s and 1.5° C. / s.

2. The control method for a reflow soldering system according to claim 1, characterized in that: The predetermined range is 30°C-50°C.

3. A reflow soldering system, characterized in that: The reflow soldering system is used to execute the control method for a reflow soldering system according to any one of claims 1-2, and the reflow soldering system includes a temperature control device. After the temperature control device heats the circuit board for a first predetermined time, when the circuit board reaches a predetermined temperature, the temperature control device cools the circuit board, and the predetermined temperature is greater than the glass transition temperature of the dielectric layer of the circuit board and less than the melting point of the solder used in the reflow soldering process.

4. The reflow soldering system according to claim 3, characterized in that: The temperature control device is a reflow furnace, which includes an inlet and an outlet. The reflow soldering system also includes a material moving component, which can transfer the soldered circuit board from the outlet to the inlet, or transfer the flattening tool removed from the circuit board at the outlet to the inlet.

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