Rapid atmosphere protection heat treatment furnace

Abstract

The invention relates to the technical field of photovoltaic battery piece production, in particular to a rapid atmosphere protection heat treatment furnace which comprises a furnace body, a plurality of temperature zones and a plurality of heating devices. The atmosphere system comprises a gas inlet channel and a gas outlet channel, the gas inlet channel and the gas outlet channel are located at the bottom and the top of the furnace body respectively, and inert gas is introduced into the furnace body through the gas inlet channel, so that the oxygen content in the furnace body is reduced; the air curtains are located at the two ends of the furnace body and used for isolating external air; the composite conveying system comprises a first conveying mechanism and a second conveying mechanism, the first conveying mechanism and the second conveying mechanism are correspondingly arranged in different temperature zones of the furnace body respectively and are always located in the thermal field environment of the furnace body in the furnace body, and rapid carrying of products under thermal treatment in the furnace is achieved. The composite conveying system completes preheating treatment in advance, and when the silicon wafer is placed and flatly laid on the surface, heat can be quickly transferred to the silicon wafer, so that the silicon wafer reaches the temperature required by curing treatment in a short time.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cell production, and particularly to a rapid atmosphere protection heat treatment furnace. Background Art

[0002] In the past production process of battery silicon wafers, a crucial step was to precisely print electrode grid lines made of silver material on the front and back of the silicon wafers, namely the positive electrode lines and the negative electrode lines. After this step, a sintering furnace was used to cure these grid paste patterns to ensure their stability and conductivity. However, with the increasing attention of the industry to cost-effectiveness, a major technological innovation is currently being actively promoted, aiming to replace the traditional silver material with a more economical and practical base metal material such as copper.

[0003] However, this technological innovation faces a significant challenge: when the original heat treatment furnace conducts sintering in its atmospheric environment, it will cause oxidation reactions of the base metal materials. This will not only affect the conductivity of the electrode grid lines but may also have an adverse impact on the overall quality of the silicon wafers. Therefore, the original heat treatment furnace cannot meet this key requirement in the processing of new materials, and there is an urgent need to develop a new sintering technology that can adapt to the characteristics of base metal materials or improve the existing heat treatment equipment.

[0004] Therefore, the present application has developed a rapid atmosphere protection heat treatment furnace to solve the problems existing in the prior art. Summary of the Invention

[0005] The object of the present invention is to provide a rapid atmosphere protection heat treatment furnace to solve the problem in the prior art that the heat treatment furnace cannot quickly complete the curing of the electrode grid lines on the silicon wafer due to the replacement of the silver material with the copper material.

[0006] The technical solution of the present invention is: a rapid atmosphere protection heat treatment furnace, comprising:

[0007] A furnace body, with a plurality of temperature zones arranged in sequence along the length direction of the furnace body;

[0008] An atmosphere system, the atmosphere system includes an intake passage and an exhaust passage, the intake passage and the exhaust passage are respectively located at the bottom and top of the furnace body, and an inert gas is introduced into the furnace body through the intake passage to reduce the oxygen content in the furnace body;

[0009] A pair of air curtains, located at both ends of the furnace body, for isolating external air;

[0010] The composite transfer system includes a first transfer mechanism and a second transfer mechanism. The first transfer mechanism and the second transfer mechanism are respectively arranged in different temperature zones of the furnace body, and are always in the thermal field environment of the furnace body, so as to realize the rapid transfer of products under heat treatment in the furnace.

[0011] Preferably, the temperature zone includes a low-temperature zone and a high-temperature zone. The temperature range of the low-temperature zone is less than or equal to 250 °C, and the range of the high-temperature zone is 250 °C to 500 °C. The first transfer mechanism is located in the low-temperature zone, and the second transfer mechanism is located in the high-temperature zone.

[0012] Preferably, the first transfer mechanism is a belt transfer structure, and the material is nylon, fiberglass plus silicon-based rubber or Teflon composite braid, with a temperature resistance of greater than or equal to 250 °C. The second transfer mechanism is a roller transfer structure, and the material is stainless steel, alumina ceramic, SiC ceramic, Si3N4.

[0013] Preferably, a plurality of air inlet channels and a plurality of air outlet channels are provided, and they are evenly distributed on the furnace body. The flow rate of the air outlet channel is less than that of the air inlet channel, so that the air pressure in the furnace body is greater than the external air pressure.

[0014] Preferably, a plurality of blowers are provided on the furnace body, and the plurality of blowers are correspondingly arranged between two adjacent air outlet channels, so as to form a circulation of the air flow in the furnace body.

[0015] Preferably, an oxygen content detection unit is provided in the furnace body, and the oxygen content detection unit is located at the junction of the low-temperature zone and the high-temperature zone to detect the oxygen content in real time and trigger an alarm.

[0016] Preferably, the surfaces of the first transfer mechanism and the second transfer mechanism are on the same horizontal plane, and the distance between them is less than 5 mm.

[0017] Preferably, during the process of transporting the product, the product is in direct contact with the first transfer mechanism and the second transfer mechanism, and is laid flat on the first transfer mechanism and the second transfer mechanism for transfer.

[0018] Preferably, the first transfer mechanism and the second transfer mechanism are both preheated and continuously rotate during the heat treatment process.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] (1) Inert gas (such as nitrogen, argon, etc.) is introduced through the intake channel, and waste gas and organic matter are discharged through the outlet channel. At both ends of the furnace body, air curtains are provided to effectively isolate the entry of external air into the furnace, keeping the oxygen content in the furnace below the threshold (such as 200 ppm), ensuring an anaerobic or low-oxygen protection environment in the furnace, preventing oxidation of the product during heat treatment, guaranteeing the heat treatment quality. At the same time, the flow rate of the outlet channel is less than that of the intake channel, maintaining a slightly positive pressure in the furnace, preventing the infiltration of external air, further reducing the oxygen content in the furnace, and reducing temperature fluctuations caused by air convection, which helps to evenly distribute the temperature in the furnace;

[0021] (2) The first conveying mechanism (belt conveying structure) is located in the low-temperature zone, and the second conveying mechanism (roller conveying structure) is located in the high-temperature zone, meeting the transmission requirements of different temperature zones. At the same time, it is not necessary to use the roller conveying method entirely, saving costs. And the compact design of the two first conveying mechanisms and one second conveying mechanism shortens the transmission time, improves the overall transmission efficiency, speeds up the production rhythm, and adapts to the production requirements of the entire production line;

[0022] (3) The composite conveying system completes preheating treatment before conveying the silicon wafers. When the silicon wafers are placed and laid flat on the surface, it can quickly transfer heat to the silicon wafers, enabling the silicon wafers to reach the temperature required for solidification treatment in a short time, improving the solidification efficiency and effect;

[0023] (4) The intake channel, the outlet channel, and the stirring fan cooperate to make the air flow in the furnace body in a dynamic equilibrium state, driving the air flow in the furnace body to form an orderly circulation path, ensuring the uniformity of the thermal field, and improving the product quality;

[0024] (5) An oxygen content detection unit is set at the junction of the low-temperature zone and the high-temperature zone to continuously monitor the oxygen content. Once it exceeds the safety threshold, an alarm is immediately triggered, effectively preventing the oxidation problem of the electrode grid lines and ensuring the stability and safety of the furnace environment. Description of the Drawings

[0025] The present invention will be further described below in conjunction with the drawings and embodiments:

[0026] Figure 1 It is a plan view of a rapid atmosphere protection heat treatment furnace according to the present invention.

[0027] Wherein: 1. Furnace body; 2. Temperature zone; 21. Low-temperature zone; 22. High-temperature zone; 3. Atmosphere system; 31. Intake channel; 32. Outlet channel; 4. Air curtain; 5. Composite conveying system; 51. First conveying mechanism; 52. Second conveying mechanism; 6. Fan. Detailed Embodiments

[0028] The following will further elaborate on the content of the present invention in conjunction with specific embodiments:

[0029] As shown Figure 1 in the figure, a rapid atmosphere-protected heat treatment furnace includes a furnace body 1, an atmosphere system 3, an air curtain 4, and a composite conveying system 5. The furnace body 1 is divided into multiple temperature zones 2 along its length direction to meet the requirements of different heat treatment processes. According to the different temperature requirements of customers, corresponding specifications and models are designed. The atmosphere system 3 consists of an intake channel 31 and an exhaust channel 32, which are respectively located at the bottom and top of the furnace body 1. Inert gas (such as nitrogen, argon, etc.) is introduced into the furnace body 1 through the intake channel 31 to reduce the oxygen content in the furnace body 1 and prevent the product from oxidizing during the heat treatment process. The exhaust channel 32 is used to discharge the waste gas and organic matter in the furnace body 1, keep the atmosphere in the furnace fresh, help create an anaerobic or low-oxygen protection environment, and ensure the quality of the heat treatment. In order to ensure that the oxygen content in the furnace is less than 200 ppm, a pair of air curtains 4 are provided at both ends of the furnace body 1, formed by inert gas, to isolate the external air from entering the furnace, make the furnace form a relatively closed environment, and ensure that the oxygen content in the furnace is less than the threshold value. Specifically, the flow rate of the exhaust channel 32 is less than that of the intake channel 31, so that the air pressure in the furnace body 1 is greater than the external air pressure, maintain a slightly positive pressure in the furnace, form a pressure difference between the inside and outside of the furnace, effectively prevent the external air from seeping into the furnace through the gaps, and thus ensure that the oxygen content in the furnace is low enough not to oxidize with the product. At the same time, when the air pressure in the furnace is higher than the outside, the air flow in the furnace will be restricted to a certain extent, reducing the temperature fluctuation caused by air convection, which helps to evenly distribute the temperature in the furnace.

[0030] In this embodiment, the composite conveying system 5 includes a first conveying mechanism 51 and a second conveying mechanism 52, which are respectively arranged in different temperature zones 2 of the furnace body 1. The first conveying mechanism 51 is located in the low-temperature zone 21 and adopts a belt conveying structure. The material is a high-temperature-resistant material (such as nylon, fiberglass plus silicon-based rubber, or Teflon composite weaving), which can withstand the temperature requirements of the low-temperature zone 21 and is between RT and 250°C. The second conveying mechanism 52 is located in the high-temperature zone 22 and adopts a roller conveying structure. The material is a high-temperature-resistant and wear-resistant material (such as stainless steel, alumina ceramic, SiC ceramic, Si3N4) to adapt to the harsh environment of the high-temperature zone 22, and the temperature is between 250°C and 500°C. In actual application, after printing the electrode grid lines made of copper material on the front and back of the silicon wafer, curing treatment is required, and at the same time, it is necessary to meet the production beat of the entire production line and adapt to the production requirements of subsequent processing processes. Therefore, it is necessary to complete the curing of the electrode grid lines on the silicon wafer within 80 - 200 seconds, and the conveying speed of the silicon wafer is required to reach 10 - 80 mm / second.

[0031] Since the belt conveying method does not have the characteristic of high temperature resistance, it cannot operate in the high temperature area 22. If the roller conveying method is selected for use in both the low temperature area 21 and the high temperature area 22, it will result in a significant increase in cost. In contrast, using the belt conveying method only in the low temperature area 21 can not only meet the product's speed requirements but also effectively save costs.

[0032] Specifically, two first conveying mechanisms 51 are provided, and one second conveying mechanism 52 is provided. The second conveying mechanism 52 is located between the two first conveying mechanisms 51 and is all located inside the furnace body 1. The silicon wafer is directly placed on the first conveying mechanism 51 near the entrance of the furnace body 1. The silicon wafer moves with the movement of the conveying mechanism and sequentially passes through the first conveying mechanism 51, the second conveying mechanism 52, and the first conveying mechanism 51 along the length direction of the furnace body 1, and then enters the next process. During the conveying process of the silicon wafer, since the silicon wafer is in direct contact with each conveying mechanism and lies flat on the corresponding first conveying mechanism 51 and second conveying mechanism 52, therefore, no matter on which conveying mechanism, the conveying mechanism can directly transfer heat to the silicon wafer through heat transfer, thereby completing the curing process.

[0033] To further illustrate, in the traditional silicon wafer curing process, the silicon wafer is usually transported through a conveying device with a mesh structure. However, this conveying device is not located inside the furnace body 1 but extends into the furnace from outside the furnace body 1 for heat treatment operations. Although this method can ensure the conveying speed of the silicon wafer, due to the relatively large heat capacity of the conveying device itself, it cannot effectively transfer heat to the silicon wafer. Therefore, when the silicon wafer has not reached the temperature required for curing, it has already been conveyed out of the furnace body 1, which obviously does not meet the requirements of the curing process. To solve this problem, this embodiment adopts a new design. Specifically, by introducing the first conveying mechanism 51 and the second conveying mechanism 52 located inside the furnace body 1, these two conveying mechanisms are in a state of continuous self-rotation during operation. More importantly, before the silicon wafer is placed on these two conveying mechanisms, they have completed the preheating process. In this way, when the silicon wafer is conveyed on the composite conveying system 5 composed of these two conveying mechanisms, due to the relatively small heat capacity of the silicon wafer itself, the conveying mechanism can quickly transfer the preheated heat to the silicon wafer, enabling the silicon wafer to reach the temperature required for curing in a short time, thereby greatly improving the efficiency and effect of the curing process and meeting the production rhythm of the production process.

[0034] Furthermore, multiple intake channels 31 and exhaust channels 32 are provided and evenly distributed on the furnace body 1 to ensure the dynamic balance of the gas in the furnace body 1. Inert gas, generally nitrogen, is conveyed into the furnace body 1 through the intake channels 31. It can effectively isolate the oxygen in the air and prevent the base metal material from undergoing oxidation reactions in a high-temperature environment, thus ensuring the smooth progress of the curing process and the excellent performance of product quality. Through the even distribution of the multiple intake channels 31, nitrogen can penetrate into every corner of the furnace in a more uniform and comprehensive manner, providing a stable and safe curing environment for the silicon wafers. The exhaust channels 32, on the other hand, are responsible for timely and efficiently discharging the waste gases generated in the furnace. These waste gases may include volatile organic compounds released during the curing process, unreacted raw material gases, and impurity gases accumulated in the furnace, etc. Through the evenly distributed exhaust channels 32, the waste gases can be guided out of the furnace in a more smooth and orderly manner, effectively avoiding the pollution of the furnace internal environment by the waste gases and the interference with the silicon wafer curing process.

[0035] To ensure that the uniformity of the thermal field in the furnace body 1 reaches the optimal state, a blower 6 is designed on the furnace body 1, and this blower 6 is a stirring blower. Specifically, multiple stirring blowers are precisely installed between adjacent exhaust channels 32. They work together to drive the air flow in the furnace body 1 to form an orderly circulation path, effectively distributing the heat evenly to all parts of the furnace body 1, thereby ensuring the uniformity of the thermal field, making the silicon wafers heat more evenly during the curing process, and improving product quality.

[0036] To ensure that the copper electrode grid lines in the furnace body 1 are protected from oxidation, an oxygen content detection unit is installed in the furnace, which can continuously monitor the oxygen content in this critical area. Once the oxygen content in the furnace exceeds the preset safety threshold, the oxygen content detection unit will immediately trigger the alarm system, timely reminding the operator to pay attention and take corresponding measures, effectively preventing the oxidation problem of the copper electrode grid lines caused by excessive oxygen content, thus ensuring the stability and safety of the furnace internal environment. Specifically, at the junction of the low-temperature zone 21 and the high-temperature zone 22, due to the large temperature difference, the oxygen concentration often changes significantly. Therefore, setting the oxygen content detection unit at this position can more sensitively capture the fluctuations of the oxygen concentration, improving the detection accuracy. Moreover, the copper electrode grid lines are more likely to undergo oxidation reactions at high temperatures. Therefore, it is necessary to closely monitor the oxygen content in the high-temperature zone 22 and issue early warnings in a timely manner to effectively prevent the oxidation of the electrode grid lines.

[0037] Furthermore, the first transfer mechanism 51 and the second transfer mechanism 52 are on the same horizontal plane, and the distance between the two transfer mechanisms is relatively close. The two transfer mechanisms being on the same horizontal plane can reduce the jolting and tilting of the silicon wafer during transmission, thereby reducing the risk of silicon wafer breakage. Moreover, the relatively close first transfer mechanism 51 and second transfer mechanism 52 can shorten the transmission time of the silicon wafer between the two mechanisms, improve the overall transmission efficiency, and help to speed up the production rhythm. At the same time, the compact design of the first transfer mechanism 51 and the second transfer mechanism 52 can reduce the floor area of the equipment, make the production line more compact and efficient, and reduce the installation and maintenance costs at the same time.

[0038] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

Claims

1. A rapid atmosphere protection heat treatment furnace, characterized in that: include: A furnace body (1), wherein a plurality of temperature zones (2) are sequentially arranged along the length direction of the furnace body (1); An atmosphere system (3), the atmosphere system (3) comprising an air inlet channel (31) and an air outlet channel (32), the air inlet channel (31) and the air outlet channel (32) being located at the bottom and the top of the furnace body (1), respectively, and an inert gas is introduced into the furnace body (1) through the air inlet channel (31) to reduce the oxygen content in the furnace body (1); A pair of air curtains (4), located at both ends of the furnace body (1), for isolating external air; The composite conveying system (5) comprises a first conveying mechanism (51) and a second conveying mechanism (52), wherein the first conveying mechanism (51) and the second conveying mechanism (52) are respectively arranged in different temperature zones (2) of the furnace body (1), and are always in the thermal field environment of the furnace body (1) in the furnace body (1), so as to realize rapid transportation of products under heat treatment in the furnace.

2. A rapid atmosphere protection heat treatment furnace according to claim 1, characterized in that: The temperature zone (2) comprises a low temperature zone (21) and a high temperature zone (22); the temperature range of the low temperature zone (21) is less than or equal to 250° C., and the temperature range of the high temperature zone (22) is 250° C. to 500° C.; the first conveying mechanism (51) is located in the low temperature zone (21), and the second conveying mechanism (52) is located in the high temperature zone (22).

3. A rapid atmosphere protection heat treatment furnace according to claim 2, characterized in that: The first transmission mechanism (51) is a belt transmission structure, made of nylon, glass fiber plus silicone rubber or Teflon composite weaving, with a temperature resistance of greater than or equal to 250°C, and the second transmission mechanism (52) is a roller transmission structure, made of stainless steel, alumina ceramics, SiC ceramics, Si3N4.

4. The rapid atmosphere protection heat treatment furnace according to claim 1, characterized in that: A plurality of the air inlet channels (31) and the air outlet channels (32) are provided and are evenly distributed on the furnace body (1); the flow rate of the air outlet channels (32) is lower than the flow rate of the air inlet channels (31), so that the air pressure in the furnace body (1) is higher than the external air pressure.

5. The rapid atmosphere protection heat treatment furnace according to claim 1, characterized in that: The furnace body (1) is provided with a plurality of fans (6), and the plurality of fans (6) are correspondingly arranged between two adjacent air outlet channels (32), so that the airflow in the furnace body (1) forms a circulation.

6. The rapid atmosphere protection heat treatment furnace according to claim 2, characterized in that: An oxygen content detection unit is provided in the furnace body (1) and is located at the junction of the low temperature zone (21) and the high temperature zone (22) to detect the oxygen content in real time and trigger an alarm.

7. The rapid atmosphere protection heat treatment furnace according to claim 1, characterized in that: The surface of the first conveying mechanism (51) and the surface of the second conveying mechanism (52) are located on the same horizontal plane, and the distance between them is less than 5 mm.

8. The rapid atmosphere protection heat treatment furnace according to claim 1, characterized in that: During the process of transporting the product, the product is in direct contact with the first conveying mechanism (51) and the second conveying mechanism (52), and is flatly laid on the first conveying mechanism (51) and the second conveying mechanism (52) for transport.

9. A rapid atmosphere protection heat treatment furnace according to any one of claims 1 to 8, characterized in that: The first conveying mechanism (51) and the second conveying mechanism (52) are both preheated and continuously rotate during the heat treatment process.

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