Vacuum reflow soldering furnace and smoke exhaust system

Abstract

The invention discloses a vacuum reflow soldering furnace and a smoke exhaust system, the vacuum reflow soldering furnace comprises a furnace body chamber, the furnace body chamber comprises a chamber upper cover and a lower chamber, and the lower chamber is hinged with the chamber upper cover; the backflow cover is arranged in the cavity upper cover, one side of the backflow cover is opened, and the opening of the backflow cover is deviated from the inner wall of the cavity upper cover; the backflow box is arranged in the cavity upper cover, the backflow box is matched with the backflow cover in shape, the backflow box is fixed at the opening of the backflow cover, the backflow box is provided with a backflow groove, and the backflow groove wraps the edge of the opening of the backflow cover by a circle. According to the smoke exhaust system, a design scheme optimized in different states is adopted, the smoke exhaust system specifically comprises the two states of the process welding process and the cooling process, the corrosion influence of scaling powder on equipment is effectively restrained, and the operation efficiency and reliability of the system are remarkably improved. And the probability of cleaning the furnace body chamber and the pipeline is reduced, the corrosion damage of the soldering flux to the furnace body chamber and the pipeline is also reduced, and the corrosion damage of the soldering flux to the vacuum pump is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum reflow soldering furnaces, and particularly relates to a vacuum reflow soldering furnace and an exhaust system. Background Art

[0002] A vacuum reflow soldering furnace is a special device for high-quality soldering of semiconductor chips in a vacuum environment, and is widely used in the precision soldering process of high-end electronic components. During the reflow soldering process, solder paste or solder tablets are used as the main soldering materials, and their properties directly affect the soldering effect. Compared with solder paste, solder tablets have the characteristics of not requiring flux, not requiring cleaning after soldering, and having a uniform layer distribution. However, in the case of special process requirements or equipment limitations, the application of flux is inevitable. The main component of flux is rosin, which has strong viscosity and corrosiveness. During the soldering process, it will volatilize into a mist and suspend in the reducing gas protection body or the furnace chamber. When it encounters the inner wall of the furnace chamber with cooling, it will adhere to the inner wall of the furnace chamber, forming a liquid with strong viscosity. When too much adheres, it will flow down along the inner wall of the furnace chamber to the bottom of the furnace chamber, causing pollution and thus affecting the soldering quality. In addition, flux residues may also reduce the heat dissipation efficiency of the printed circuit board (PCB), affect the solder joint performance, and even interfere with temperature control, increasing the difficulty of equipment maintenance.

[0003] The utility model with the application number 202121634696 discloses a vacuum chamber with a flux recovery function, which relates to the technical field of vacuum reflow soldering. It includes a chamber body, and recovery devices are arranged on the inner side walls of the chamber body. The recovery device includes a mounting plate connected to the inner side wall of the chamber body. A recovery groove is opened at the top of the mounting plate, and the recovery groove is connected with a diversion plate. The diversion plates are all arranged obliquely upward. When too much flux adheres to the inner wall of the vacuum chamber, it will flow downwards. After flowing onto the diversion plate, it will automatically flow into the recovery groove, preventing it from flowing to the bottom of the vacuum chamber.

[0004] The defect of its recovery device installed on the inner side wall of the chamber body is that generally, devices such as heating lamps and product carriers are arranged inside the chamber body, and the internal structure is complex. Since the recovery devices are installed on the four inner side walls of the chamber body, the available space of the chamber body is greatly reduced. In addition, it is necessary to remove the recovery devices one by one to clean the flux, and it is not convenient to install it in a vacuum reflow soldering furnace with a chamber upper cover. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the present invention provides a vacuum reflow soldering furnace and a smoke exhaust system, which adopts a design scheme optimized by states, specifically including two states: the process soldering process and the cooling process. It not only effectively suppresses the corrosion effect of the flux on the equipment, but also significantly improves the operation efficiency and reliability of the system. It reduces the probability of cleaning the furnace chamber and pipelines, and also reduces the corrosion damage of the flux to the furnace chamber and pipelines. It also plays a role in protecting the vacuum pump and avoids the corrosion damage of the flux to the vacuum pump.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A vacuum reflow soldering furnace, comprising A furnace chamber, which includes an upper chamber cover and a lower chamber, and the lower chamber is hinged to the upper chamber cover; A reflux hood arranged in the upper chamber cover, one side of the reflux hood is open, and the open end of the reflux hood faces away from the inner wall of the upper chamber cover; A reflux box arranged in the upper chamber cover, the reflux box is matched with the shape of the reflux hood, the reflux box is fixed at the open end of the reflux hood, and the reflux box has a reflux groove, and the reflux groove wraps around the edge of the open end of the reflux hood for one week.

[0007] Further, the back side of the reflux hood is fixed to the inner wall of the upper chamber cover, the open edge of the reflux hood extends towards each other to form connecting ears, and the reflux hood is fixed to the reflux box through the connecting ears.

[0008] Further, the cross-section of the reflux box is a U-shaped structure, the inner side of the reflux groove is arranged close to the edge of the connecting ear, and there is a gap between the outer side of the reflux groove and the reflux hood.

[0009] Further, the upper chamber cover is also provided with at least one water-cooling channel, the water-cooling channel is located on the side of the upper chamber cover where the reflux box is installed, and the water-cooling channel penetrates through the upper chamber cover.

[0010] In addition, the present invention also claims protection for a smoke exhaust system, which includes any one of the above-mentioned vacuum reflow soldering furnaces, and also includes a low-smoke exhaust pipeline, a high-smoke exhaust pipeline, a vacuum pumping device, and a smoke exhaust pipe respectively communicated with the low-smoke exhaust pipeline and the high-smoke exhaust pipeline. The low-smoke exhaust pipeline and the high-smoke exhaust pipeline are both communicated with the vacuum reflow soldering furnace, and the vacuum pumping device is communicated with the low-smoke exhaust pipeline through a second stop valve, and the vacuum pumping device can discharge the smoke to the smoke exhaust pipe.

[0011] Further, the low-smoke exhaust pipeline includes a plate heat exchanger, a first filter, and a one-way valve connected in sequence. The plate heat exchanger is communicated with the vacuum reflow soldering furnace, the first filter is used to filter the smoke from the vacuum reflow soldering furnace, and the one-way valve is communicated with the smoke exhaust pipe.

[0012] Further, the high-smoke exhaust pipeline includes a first stop valve, a second filter, and a fan that are connected in sequence. The second filter is used to filter the smoke from the vacuum reflow soldering furnace, and the fan is connected to the exhaust pipe.

[0013] Further, both the first filter and the second filter are oil fume separators.

[0014] Further, the vacuum pumping device is a vacuum pump.

[0015] Compared with the prior art, the beneficial effects of this solution are as follows: 1. The present invention provides a vacuum reflow soldering furnace and an exhaust system, which includes a low-smoke exhaust pipeline, a high-smoke exhaust pipeline, a vacuum pumping device, and an exhaust pipe that is respectively connected to the low-smoke exhaust pipeline and the high-smoke exhaust pipeline. Both the low-smoke exhaust pipeline and the high-smoke exhaust pipeline are connected to the vacuum reflow soldering furnace. The vacuum pumping device is connected to the low-smoke exhaust pipeline through a second stop valve, and the vacuum pumping device can discharge the smoke to the exhaust pipe. The exhaust system adopts a design scheme of state-based optimization, specifically including two states: the process welding process and the cooling process. This design of the exhaust system with multi-state adjustment not only effectively inhibits the corrosion effect of the soldering flux on the equipment, but also significantly improves the operation efficiency and reliability of the system. Only the first filter and the second filter need to be cleaned or replaced regularly, reducing the probability of cleaning the furnace body chamber and pipelines, and also reducing the corrosion damage of the soldering flux to the furnace body chamber and pipelines. The first filter and the second filter also play a role in protecting the vacuum pump, avoiding the corrosion damage of the soldering flux to the vacuum pump.

[0016] 2. After the chamber upper cover of the furnace body chamber of the present invention is covered on the lower chamber, due to heat, the soldering flux vaporizes and volatilizes into a mist and suspends in the furnace body chamber. The outer wall of the reflux cover contacts the chamber upper cover. When it encounters the cooled outer wall of the reflux cover, it will adhere to the inner wall of the reflux cover and condense into a liquid. When more liquid adheres, it will flow down along the inner wall of the reflux cover under the action of gravity until it flows into the U-shaped reflux box. The cooperation of the reflux cover and the reflux box can prevent the soldering flux from flowing into the lower chamber of the furnace body chamber. When cleaning the furnace body chamber, only need to open the chamber upper cover to clean. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of this vacuum reflow soldering furnace; Figure 2 is a cross-sectional view of the vacuum reflow soldering furnace; Figure 3 is a schematic structural diagram of the reflux box; Figure 4 is a schematic structural diagram of the reflux cover; Figure 5 is a schematic diagram of the exhaust system.

[0018] The reference numerals are as follows in sequence: Upper cover 1 of the chamber, water-cooling channel 11, lower chamber 2, reflux hood 3, connecting ear 31, nut 32, reflux box 4, reflux groove 41, low-smoke exhaust pipe line 5, plate heat exchanger 51, first filter 52, check valve 53, high-smoke exhaust pipe line 6, first shut-off valve 61, second filter 62, fan 63, vacuum pumping device 7, second shut-off valve 71, exhaust pipe 8. Detailed implementation manners

[0019] The present invention will be further described in detail below with reference to the accompanying drawings.

[0020] A vacuum reflow soldering furnace, as Figure 1 and Figure 2 shown, includes a furnace body chamber, which includes an upper cover 1 of the chamber and a lower chamber 2, and the lower chamber 2 is hinged to the upper cover 1 of the chamber; A reflux hood 3 disposed in the upper cover 1 of the chamber, one side of the reflux hood 3 is open, and the open side of the reflux hood 3 faces away from the inner wall of the upper cover 1 of the chamber; A reflux box 4 disposed in the upper cover 1 of the chamber, the reflux box 4 is matched with the shape of the reflux hood 3, the reflux box 4 is fixed at the open side of the reflux hood 3, the reflux box 4 has a reflux groove 41, and the reflux groove 41 covers the periphery of the open edge of the reflux hood 3.

[0021] According to a specific embodiment provided by the present invention, during operation, the temperature of the furnace body chamber is relatively high (the upper limit is 450 °C). After the upper cover 1 of the chamber is covered on the lower chamber 2, the flux is liquefied on the reflux hood 3 by cooling. The reflux box 4 is fixed at the open side of the reflux hood 3. When the upper cover 1 of the chamber is covered on the lower chamber 2, the side wall of the reflux box 4 is in a vertical state. The reflux box 4 has a reflux groove 41 for accommodating the liquefied flux, and the reflux groove 41 covers the periphery of the open edge of the reflux hood 3. The reflux hood 3 is used to drain the liquefied flux into the reflux groove 41 of the reflux box 4, and the flux becomes solid when the temperature of the furnace body chamber drops to room temperature.

[0022] In this embodiment, the specific structure of the upper cover 1 of the chamber is not limited. However, taking the upper cover 1 of the chamber as a rectangular structure as an example, the reflux hood 3 is a structure matching the upper cover 1 of the chamber, and the reflux box 4 is a square groove-shaped structure. The height of the reflux hood 3 is not limited, but the height of the reflux hood 3 is less than the thickness of the upper cover 1 of the chamber, that is, the reflux hood 3 needs to be located inside the upper cover 1 of the chamber. The area of the reflux hood 3 is slightly smaller than the area of the upper cover 1 of the chamber. In this way, after the reflux hood 3 is installed inside the upper cover 1 of the chamber, there is a slight gap between the reflux hood 3 and the upper cover 1 of the chamber, so as to facilitate the installation of the reflux box 4.

[0023] Furthermore, as Figure 4As shown, the back side of the reflux cover 3 is fixed to the inner wall of the chamber upper cover 1. The open edges of the reflux cover 3 extend towards each other to form connecting ears 31, and the reflux cover 3 is fixed to the reflux box 4 through the connecting ears 31.

[0024] Specifically, four screw holes are opened on the back side of the reflux cover 3, and the reflux cover 3 is fixed to the inner wall of the chamber upper cover 1 through the four screw holes. That is, when the chamber upper cover 1 is covered on the lower chamber 2, the open edges of the reflux cover 3 extend horizontally to form connecting ears 31. The open edges of the square reflux cover 3 form four connecting ears 31, and nuts 32 are respectively fixed to the four connecting ears 31. The connecting ears 31 are fixed to the inner bottom wall of the reflux groove 41 through the nuts 32. Of course, the connecting ears 31 in this embodiment can also be fixed to the open edges of the reflux cover 3 by welding.

[0025] Furthermore, as Figure 3 shown, the cross-section of the reflux box 4 is a U-shaped structure. The inner side of the reflux groove 41 is arranged close to the edge of the connecting ear 31, and there is a gap between the outer side of the reflux groove 41 and the reflux cover 3. In this way, when the liquid soldering flux flows down along the reflux cover 3, the reflux groove 41 can respectively hold the solidified soldering flux on both sides of the reflux cover 3.

[0026] Furthermore, at least one water-cooling channel 11 is also opened on the chamber upper cover 1. The water-cooling channel 11 is located on the side of the chamber upper cover 1 where the reflux box 4 is installed, and the water-cooling channel 11 penetrates through the chamber upper cover 1.

[0027] According to a specific embodiment provided by the present invention, the water-cooling channels 11 can be distributed on the surface of the chamber upper cover 1. The main function of the water-cooling channels 11 is to cool the chamber upper cover 1 of the furnace body chamber through a water-cooling circulation system, and at the same time form a temperature gradient with the reflux cover 3. After the soldering flux vaporizes due to heat, it volatilizes into a mist and suspends in the furnace body chamber. The outer wall of the reflux cover 3 contacts the chamber upper cover 1. When it encounters the cooled outer wall of the reflux cover 3, it will adhere to the inner wall of the reflux cover 3 and condense into a liquid. When there is more adhesion, it will flow down along the inner wall of the reflux cover 3 under the action of gravity until it flows into the U-shaped reflux box 4. The cooperation of the reflux cover 3 and the reflux box 4 can prevent the soldering flux from flowing into the lower chamber 2 of the furnace body chamber. When cleaning the furnace body chamber, only need to open the chamber upper cover 1 for cleaning.

[0028] In addition, the present invention also claims a smoke exhaust system, as Figure 5As shown, it includes any one of the above vacuum reflow soldering furnaces, and also includes a low-smoke exhaust pipe 5, a high-smoke exhaust pipe 6, a vacuum pumping device 7, and an exhaust pipe 8 that is respectively connected to the low-smoke exhaust pipe 5 and the high-smoke exhaust pipe 6. Both the low-smoke exhaust pipe 5 and the high-smoke exhaust pipe 6 are connected to the vacuum reflow soldering furnace. The vacuum pumping device 7 is connected to the low-smoke exhaust pipe 5 through a second stop valve 71, and the vacuum pumping device 7 can discharge the smoke to the exhaust pipe 8. In this embodiment, the low-smoke exhaust pipe 5, the high-smoke exhaust pipe 6, and the vacuum pumping device 7 are connected by pipelines. The low-smoke exhaust pipe 5 is used when the smoke in the vacuum reflow soldering furnace is less, and the high-smoke exhaust pipe 6 is used when the smoke in the vacuum reflow soldering furnace is more.

[0029] Further, the low-smoke exhaust pipe 5 includes a plate heat exchanger 51, a first filter 52, and a check valve 53 that are connected in sequence. The plate heat exchanger 51 is connected to the vacuum reflow soldering furnace. The first filter 52 is used to filter the smoke from the vacuum reflow soldering furnace. The check valve 53 is connected to the exhaust pipe 8. The plate heat exchanger 51, the first filter 52, and the check valve 53 are connected by pipelines. One end of the plate heat exchanger 51 is the cooling water inlet, and the other end is the cooling water outlet, which conducts heat exchange on the nitrogen medium from the furnace chamber. The check valve 53 is also called a non-return valve or a one-way valve, which is used to prevent the reverse flow of oil in the hydraulic system. Any product on the market that can meet the above requirements can be used for the check valve 53 in this embodiment.

[0030] Further, the high-smoke exhaust pipe 6 includes a first stop valve 61, a second filter 62, and a fan 63 that are connected in sequence. The second filter 62 is used to filter the smoke from the vacuum reflow soldering furnace. The fan 63 is connected to the exhaust pipe 8. The first stop valve 61, the second filter 62, and the fan 63 are connected by pipelines.

[0031] In this embodiment, the first stop valve 61 is connected to the lower chamber 2. A plate heat exchanger 51 can also be provided between the first stop valve 61 and the lower chamber 2. The plate heat exchanger 51 is connected to the vacuum reflow soldering furnace to conduct heat exchange on the nitrogen medium from the furnace chamber.

[0032] Further, both the first filter 52 and the second filter 62 are oil fume separators.

[0033] According to a specific embodiment provided by the present invention, when in a positive pressure state (there is also a low positive pressure environment in a vacuum reflow soldering furnace, such as in cases of rapid cooling with inert gas or filling of process gas), two working conditions are presented according to the differences in the thermal decomposition characteristics of the solder flux. In the low-smoke working condition: the first cut-off valve 61 and the second cut-off valve 71 are synchronously locked. The nitrogen medium from the furnace chamber undergoes heat exchange through the plate heat exchanger 51, and then sequentially passes through the first filter 52 and the check valve 53 (at this time, the check valve 53 is in an open state due to the positive pressure of the system), and finally is cleanly discharged through the exhaust pipe 8. In the high-smoke working condition: the second cut-off valve 71 remains locked, the first cut-off valve 61 is opened, and the fan 63 is started. A second filter 62 is configured upstream of the fan 63 to pre-purify the impurity-containing air flow. The system first performs the smoke extraction operation in the furnace chamber. After the concentration drops to the threshold value, the first cut-off valve 61 is closed, the second cut-off valve 71 is opened, and it is switched to the cooling nitrogen flushing mode. The discharge path is the same as that in the low-smoke working condition.

[0034] When the system enters the vacuum state, the first cut-off valve 61 is in the locked position while the second cut-off valve 71 is opened and conducting. In this stage, the solder flux undergoes a gasification reaction when heated and is transformed into a misty form suspended in the furnace chamber. Driven by the negative pressure of the vacuum pump, the high-temperature mixed gas flow first passes through the plate heat exchanger 51 - this device adopts a water-air double-channel heat exchange structure, and the circulating water system actively cools the high-temperature gas flow. After heat exchange, the atomized solder flux enters the first filter 52 along with the cooling air flow, condenses into a viscous gel on the surface of the filter element and is intercepted. At this time, the check valve 53 is in a closed state due to the negative pressure of the system, and the clean gas is pumped out by the vacuum pump.

[0035] By setting the first filter 52 and the second filter 62, the misty solder flux suspended in the protective gas or the vacuum chamber can be filtered, and the smoke-containing gas can be absorbed during the exhaust in the low-smoke working condition or the high-smoke working condition, avoiding the pollution of the vacuum oil and affecting its service life, corroding the vacuum pipeline and the vacuum pump, and affecting their service lives.

[0036] Further, the vacuum pumping device 7 is a vacuum pump.

[0037] The exhaust system of the present invention adopts a design scheme optimized by state, specifically including two states: the process welding process and the cooling process. This design of the exhaust system with multi-state adjustment not only effectively suppresses the corrosion effect of the solder flux on the equipment, but also significantly improves the operating efficiency and reliability of the system. Only the first filter 52 and the second filter 62 need to be cleaned or replaced regularly, reducing the probability of cleaning the furnace chamber and the pipeline, and also reducing the corrosion damage of the solder flux to the furnace chamber and the pipeline. The first filter 52 and the second filter 62 also play a role in protecting the vacuum pump, avoiding the corrosion damage of the solder flux to the vacuum pump.

[0038] Finally, it should be noted that in the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "vertical", "upper", "lower", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0039] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "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 mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0040] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A vacuum reflow oven, characterized in that: include A furnace chamber, comprising a chamber upper cover and a lower chamber, wherein the lower chamber is hinged to the chamber upper cover; A reflux hood is arranged in the upper cover of the chamber, one side of the reflux hood is open, and the open end of the reflux hood faces away from the inner wall of the upper cover of the chamber; A reflux box is arranged in the upper cover of the chamber, the shape of the reflux box matches that of the reflux cover, the reflux box is fixed at the opening of the reflux cover, and the reflux box has a reflux groove, which covers a circle around the opening edge of the reflux cover.

2. A vacuum reflow oven according to claim 1, characterized in that: The back side of the reflux cover is fixed to the inner wall of the chamber upper cover, and the open edges of the reflux cover extend toward each other to form connecting ears, and the reflux cover is fixed to the reflux box through the connecting ears.

3. A vacuum reflow oven according to claim 2, characterized in that: The cross section of the reflux box is a U-shaped structure, the inner side of the reflux groove is arranged close to the edge of the connecting ear, and a gap is left between the outer side of the reflux groove and the reflux cover.

4. A vacuum reflow oven according to any one of claims 1 to 3, characterized in that: The chamber upper cover is also provided with at least one water cooling channel, the water cooling channel is located on the side of the chamber upper cover where the reflux box is installed, and the water cooling channel runs through the chamber upper cover.

5. A smoke exhaust system, characterized in that: A vacuum reflow soldering furnace comprising the method according to any one of claims 1 to 4, further comprising a low smoke exhaust pipeline, a high smoke exhaust pipeline, a vacuum pumping device and exhaust pipes respectively connected to the low smoke exhaust pipeline and the high smoke exhaust pipeline, wherein the low smoke exhaust pipeline and the high smoke exhaust pipeline are both connected to the vacuum reflow soldering furnace, the vacuum pumping device is connected to the low smoke exhaust pipeline via a second stop valve, and the vacuum pumping device can discharge smoke into the exhaust pipe.

6. A smoke exhaust system according to claim 5, characterized in that: The low smoke exhaust pipeline includes a plate heat exchanger, a first filter and a one-way valve which are connected in sequence. The plate heat exchanger is connected to the vacuum reflow oven. The first filter is used to filter the smoke from the vacuum reflow oven. The one-way valve is connected to the smoke exhaust pipe.

7. A smoke exhaust system according to claim 6, characterized in that: The high smoke exhaust pipeline comprises a first stop valve, a second filter and a fan which are connected in sequence, the second filter is used to filter the smoke from the vacuum reflow oven, and the fan is connected to the smoke exhaust pipe.

8. A smoke exhaust system according to claim 7, characterized in that: The first filter and the second filter are both oil fume separators.

9. A smoke exhaust system according to any one of claims 5 to 8, characterized in that: The vacuum pump is a vacuum pump.

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