Technical Field

[0001] The present application relates to a furnace, in particular to a furnace for drying photovoltaic devices.

Background

[0002] In the production of photovoltaic devices such as silicon wafers of crystalline silicon solar cells, a sintering furnace is required to sinter the photovoltaic devices. The sintering furnace typically includes a drying section, a sintering section, and a cooling section. Here, photovoltaic devices printed with slurry such as silver slurry are transported by a conveyor belt through the drying section, the sintering section and the cooling section in this order, and then transported out of the sintering furnace by the conveyor belt.

Summary

[0003] At least one object in a first aspect of the present application is to provide a furnace, including: a furnace chamber and a conveying device. The furnace chamber includes an upper furnace chamber and a lower furnace chamber arranged opposite to each other, with a conveying space extending through the furnace chamber along a length direction of the furnace chamber between the upper furnace chamber and the lower furnace chamber. The conveying device is used to carry and move a processing element in the conveying space through the furnace chamber. Here, in a height direction of the furnace chamber, the conveying space includes a conveying device receiving space and a processing element receiving space. The conveying device receiving space is located below the processing element receiving space, the conveying device being received in the conveying device receiving space, the processing element receiving space being used to receive the processing element when the processing element is carried on the conveying device in an upright position.

[0004] According to the first aspect described above, the upper furnace chamber includes a pair of upper furnace chamber sides oppositely disposed in a width direction of the furnace chamber and extending along the length direction of the furnace chamber. The lower furnace chamber includes a pair of lower furnace chamber sides oppositely disposed in the width direction of the furnace chamber and extending along the length direction of the furnace chamber. Here, the pair of upper furnace chamber sides and the pair of lower furnace chamber sides are connected accordingly. Moreover, in the height direction of the furnace chamber, the bottom of the furnace chamber is spaced a distance from the bottom of the pair of upper furnace chamber sides, and the top of the lower furnace chamber and the top of the pair of lower furnace chamber sides are spaced a distance such that the conveying space is formed between the bottom of the upper furnace chamber and the top of the lower furnace chamber. Here, the furnace chamber further includes a pair of side elevations. The pair of side elevations are disposed oppositely in the width direction of the furnace chamber and extends along the length direction of the furnace chamber. The pair of side elevations are provided at the bottom of the upper furnace chamber side and/or at the top of the lower furnace chamber side so that when the processing element is carried on the conveying device in an upright position, the processing element receiving space is capable of accommodating the processing element.

[0005] According to the first aspect described above, the pair of side elevations are respectively provided on top of the pair of lower furnace chamber sides and connected with the pair of upper furnace chamber sides.

[0006] According to the first aspect described above, the furnace further includes a hinge device. The hinge device includes a connecting rod and a supporting rod. The connecting rod is connected with the upper furnace chamber, the supporting rod is fixed, and the connecting rod and the supporting rod are rotatably connected by a shaft, wherein the hinge device is configured to be capable of opening the upper furnace chamber relative to the lower furnace chamber by driving the connecting rod to rotate relative to the supporting rod.

[0007] According to the first aspect described above, the height of the processing element receiving space is 200 to 300 mm. [0008] According to the first aspect described above, the furnace is configured to provide heating to dry the processing element, thereby removing organic matter from the processing element.

[0009] According to the first aspect described above, the furnace chamber includes a plurality of heating units, each heating unit being arranged side-by-side along the length direction of the furnace chamber and configured to each independently provide the heat through a heating element.

[0010] According to the first aspect described above, each of the heating units includes a fan assembly, an upper divider and a lower divider, the upper divider being disposed in the upper furnace chamber, and the bottom of the upper divider forming a bottom of the upper furnace chamber, the lower divider being disposed in the lower furnace chamber, and the top of the lower divider forming a top of the lower furnace chamber, wherein the fan assembly, the upper divider and the lower divider are configured for gas in the heating unit to flow within respective units such that the heat provided by the heating elements is spread evenly to the processing element.

[0011] According to the first aspect described above, the furnace further includes two end barriers, which are respectively provided at an inlet end and an outlet end of the furnace chamber, wherein each of the end barriers includes a gas curtain device and an exhaust device, and the end barrier is configured to block the flow of gas between the interior and exterior environments of the furnace chamber so that the oxygen content in the gas inside the furnace chamber reaches a preset value.

[0012] According to the first aspect described above, the processing element is a photovoltaic device.

[0013] According to the first aspect described above, the processing element is a circuit board, and the furnace is configured for reflow soldering the circuit board.

[0014] At least one object in a second aspect of the present application is to provide a sintering furnace including a drying section, a sintering section, and a cooling section. Here, the drying section includes the furnace of any one in the first aspect.

[0015] Other objects and advantages of the present application will be apparent from the description of the present application hereinafter with reference to the accompanying drawings, and may help with a full understanding of the present application.

Brief Description of Drawings

[0016] Fig. 1 is a perspective view of a furnace according to an example of the present application;

[0017] Fig. 1 B is a schematic diagram of the principle of the furnace shown in Fig. 1A;

[0018] Fig. 2A is a perspective view of a furnace chamber in Fig. 1A;

[0019] Fig. 2B is a cross-sectional view of the furnace chamber in Fig. 2A along a width direction;

[0020] Fig. 2C is a partial cross-sectional view of the furnace chamber in Fig. 2A along long width directions;

[0021] Fig. 3 is a schematic view of a sintering furnace including the furnace shown in Fig. 1A.

Detailed Description

[0022] Various specific embodiments of the present application will be described below with reference to the attached drawings that form a part of the present specification. It should be understood that while terms denoting orientation, such as “front,” “rear,” “upper,” “lower,” “left,” “right,” “top,” “bottom,” “inside,” “outside,” etc., are used in the present application to describe various exemplary structural parts and elements of the present application, these terms are used herein for convenience of illustration only and are determined based on the exemplary orientations shown in the attached drawings. Since the examples disclosed in the present application may be disposed in different orientations, these terms denoting orientation are for illustrative purposes only and should not be considered as limiting.

[0023] Figs. 1A and 1 B are structural diagrams of a furnace 100 according to one example of the present application, wherein Fig. 1A is a perspective view and Fig. 1 B is a simplified schematic diagram. As shown in Figs. 1A and 1 B, the furnace 100 includes a furnace chamber 112, a conveying device 118, and a bracket 111 , the furnace chamber 112 being supported above the bracket 111. The furnace chamber 112 includes an upper furnace chamber 113 and a lower furnace chamber 114, and a conveying space 120 disposed between the upper furnace chamber 113 and the lower furnace chamber 114. The conveying space 120 extends through the furnace chamber 112 along a length direction L of the furnace chamber 112. The conveying device 118 passes through the furnace chamber 112 along the length direction L of the furnace chamber 112 for carrying and moving a processing element 110 from an inlet end 151 of the furnace chamber 112 (i.e., the left end in Fig. 1 B) into the conveying space 120 and out from an outlet end 152 of the furnace chamber 112 (i.e., the right end in Fig. 1 B) after moving through the furnace chamber 112 in the conveying space 120. The conveying device 118 is used to carry and move the processing element 110 through the furnace chamber 112 in the conveying space 120 along the conveying direction. The conveying device 118 includes a conveyor belt 115 on which the processing element 110 is carried.

[0024] In the height direction H of the furnace chamber 112, the conveying space 120 is formed between a bottom 135 of the upper furnace chamber 113 and a top 136 of the lower furnace chamber 114. The conveying space 120 includes a conveying device receiving space 142 and a processing element receiving space 141 , and the conveying device receiving space 142 is located below the processing element receiving space 141. The conveying device receiving space and the processing element receiving space 141 are formed separated by the conveyor belt 115 for carrying the processing element 110. The processing element receiving space 141 has a height D1 , i.e., the bottom 135 of the upper furnace chamber 113 is spaced D1 from the conveyor belt 115, and the processing element receiving space 141 is used to accommodate the processing element 110. The conveying device receiving space 142 has a height D2, i.e., the top 136 of the lower furnace chamber 114 is spaced D2 from the conveyor belt 115, and the conveying device receiving space 142 is used to accommodate the conveying device 118. In the examples of the present application, the processing element 110 is placed in an upright position on the conveyor belt 115 of the conveying device 118, and the height D1 of the processing element receiving space 141 is set to match the maximum height of the processing element 110 so that the processing element receiving space 141 can accommodate the processing element 110 when placed in an upright position.

[0025] In the length direction L of the furnace chamber 112, the furnace 100 includes two end barriers 108 disposed at the inlet end 151 and the outlet end 152 of the furnace chamber, and a plurality of heating units 101 and at least one cooling unit 102 disposed between the two end barriers 108. The end barrier 108 is used to block the flow of gas between the interior and exterior environments of the furnace chamber 112 so that the oxygen content in the gas inside the furnace chamber 112 can be controlled within a predetermined range. In the present example, each end barrier 108 includes a gas curtain device 109 and an exhaust device 154, and the exhaust device 154 is disposed outside of the gas curtain device 109. The exhaust device 154 is used to exhaust air from the inlet end 151 and the outlet end 152 of the furnace chamber. The gas curtain device 109 includes a pair of end barrier boxes 107, the air outlets of the pair of end barrier boxes 107 being placed face to face. Each end barrier box 107 is in fluid communication with an inert gas source 153a and an inert gas source 153b respectively to generate a gas curtain by the opposing flow of inert gas streams. While the end barrier box 107 in the upper furnace chamber 113 and the end barrier box 107 in the lower furnace chamber 114 shown in Fig. 1 B are connected to different inert gas sources, in other examples they may also be connected to the same inert gas source. By providing the exhaust 154 and the gas curtain device 109, the gas circulation inside and outside of the furnace chamber 112 can be reduced or substantially blocked. Further, the inert gas source 153a is also in fluid communication with the middle of the furnace chamber 112 to input an inert gas into the interior of the furnace chamber 112. The input inert gas flows from the middle of the furnace chamber 112 in a direction towards the inlet end 151 and the outlet end 152, enabling better blocking of air from the environment outside the furnace chamber 112 from entering the interior of the furnace chamber 112. The specific structure of the gas curtain device 109 will be described in detail with reference to Figs. 2A to 2C. In other examples, the end barrier 108 may also be provided with other structures or other means to block the flow of gas inside and outside the furnace chamber 112, depending on specific needs.

[0026] The plurality of heating units 101 and at least one cooling unit 102 are disposed side-by-side along the length direction L of the furnace chamber 112, and the heating units 101 are disposed upstream in the conveying direction and the cooling unit 102 is disposed downstream in the conveying direction. Each heating unit 101 is provided with an independent heating element 103 to each independently provide heat through the heating element 103. Each cooling unit 102 is provided with an independent cooling element (not shown in the figures) to each independently provide cooling through the cooling elements. In the present example, the heating element 103 is a heating rod and the cooling element is an air-cooled heat exchanger or a water-cooled heat exchanger. Each heating unit 101 and each cooling unit 102 are further provided with a fan assembly 104 and a divider assembly (see upper divider 245 and lower divider 246 in Figs. 2A to 2C). By providing separate fan assembly 104 and divider assembly for each heating unit 101 and each cooling unit 102, the gas within each heating unit 101 and each cooling unit 102 can flow inside the respective unit according to a certain flow path, thereby enabling the heat and cooling provided by the heating element 103 and the cooling element to spread evenly to the processing element 110.

[0027] In the length direction L of the furnace chamber 112, the furnace 100 also includes a plurality of hinge devices 121 fixedly connected above the upper furnace chamber 113. The hinge device 121 is capable of driving the upper furnace chamber 113 to move relative to the lower furnace chamber 114, thereby opening the upper furnace chamber 113 to expose the conveying space 120.

[0028] In the present example, the processing element 110 is a photovoltaic device, such as a sheet of silicon wafer printed with a slurry, and the furnace 100 is used to dry the photovoltaic device and remove organic matter such as organic solvents in the slurry to facilitate subsequent sintering of the photovoltaic device. In other examples, the processing element 110 may also be a circuit board and the furnace 100 is used to reflow solder electronic components on the circuit board.

[0029] Figs. 2A to 2C show the specific structure of the furnace chamber 112 of the furnace 100 of the present application, wherein Fig. 2A is a perspective view of the furnace chamber 112, Fig. 2B is a cross-sectional view along a width direction of the furnace chamber 112, and Fig. 2C is a partial cross-sectional view along a length direction of the furnace chamber 112. As shown in Figs. 2A to 2C, the upper furnace chamber 113 includes an upper furnace chamber top 233 and a pair of upper furnace chamber sides 231 . The pair of upper furnace chamber sides 231 are connected to two opposite sides of the upper furnace chamber top 233 in a width direction W, and each upper furnace chamber side 231 extends along the length direction L. The lower furnace chamber 114 includes a lower furnace chamber bottom 234 and a pair of lower furnace chamber sides 232. The pair of lower furnace chamber sides 232 are connected to two opposite sides of the lower furnace chamber bottom 234 in the width direction W, and each lower furnace chamber side 232 extends along the length direction L. The bottom edge of each upper furnace chamber side 231 folds outwardly to form an upper furnace chamber joint 263, the bottom edge of each lower furnace chamber side 232 folds outwardly to form a lower furnace chamber joint 264, and the upper furnace chamber joint 263 and the lower furnace chamber joint 264 are hermetically connected together by a long strip-like sealing member 227 extending along the length direction L so that the upper furnace chamber 113 and the lower furnace chamber 114 can be connected together by their respective sides. As such, the furnace chamber 112 is sealed in the width direction W, preventing gas within the furnace chamber 112 from spilling from both sides in the width direction W. The bottom edge of the upper furnace chamber side 231 is spaced a distance from the bottom 135 of the upper furnace chamber 113, and the top edge of the lower furnace chamber side 232 is spaced a distance from the top 136 of the lower furnace chamber 114. Therefore, when the upper furnace chamber side 231 and the lower furnace chamber side 232 are connected together, the conveying space 120 can be formed between the bottom 135 of the upper furnace chamber 113 and the top 136 of the lower furnace chamber 114. It will be appreciated by those skilled in the art that in the present application, the bottom 135 of the upper furnace chamber 113 refers to the bottom of the upper furnace chamber 113 between the pair of upper furnace chamber sides 231 and the top 136 of the lower furnace chamber 114 refers to the top of the lower furnace chamber 114 between the pair of lower furnace chamber sides 232. In particular, the upper furnace chamber 113 further includes an upper divider 245, the bottom of the upper divider 245 forming the bottom 135 of the upper furnace chamber 113. The lower furnace chamber 114 also includes a lower divider 246, the top of the lower divider 246 forming the top 136 of the lower furnace chamber 114.

[0030] To enable the processing element receiving space 141 of the conveying space 120 to accommodate the processing elements 110 in an upright position, the furnace chamber 112 further includes a pair of side elevations 140 extending along the length direction L, the pair of side elevations 140 being disposed on two opposite sides in the width direction W of the furnace chamber 112 and disposed on the bottom of the upper furnace chamber side 231 and/or the top of the lower furnace chamber side 232. In contrast to a furnace that does not include the side elevations 140, by providing a pair of side elevations 140 in the furnace 100, the height of the conveying space 120 can be increased, so that the height of the processing element receiving space 141 can be raised to D1 , i.e. , to satisfy the height requirements of the processing element placed in an upright position, while the height D2 of the conveying device receiving space 142 remains unchanged. In the present example, the pair of side elevations 140 are respectively provided on top of the pair of lower furnace chamber sides 232 and are connected with the respective pair of upper furnace chamber sides 231 . It will be appreciated by those skilled in the art that the pair of side elevations 140 may also be provided at the bottom of the pair of upper furnace chamber sides 231 and connected with the respective pair of lower furnace chamber sides 232. Alternatively, the pair of side elevations 140 are respectively provided at the bottom of one upper furnace chamber side 231 and at the top of a corresponding lower furnace chamber side 232. It is fine as long as the height of the processing element receiving space 141 can be increased by increasing the height of the sidewalls of the furnace chamber. In some other examples, if the height of the processing element 110 placed in an upright position on the conveyor belt 115 is small, the height D1 of the processing element receiving space 141 may also be increased by reducing the height D2 of the conveying device receiving space 142 while keeping the height of the conveying space 120 unchanged. At this point, only the height of a pair of guide rails 219 of the conveying device 118 needs to be lowered. As a more specific example, the height of the processing element receiving space 241 is about 200 to 300 mm, which can meet the size requirements of most photovoltaic devices.

[0031] The hinge device 121 includes a connecting rod 224 and a supporting rod 222, and the connecting rod 224 includes a vertical section and a lateral section, the lateral section being fixedly connected above the top 233 of the upper furnace chamber 113. The supporting rod 222 is also secured, for example, on the bracket 111. One end of the vertical section of the connecting rod 224 and one end of the supporting rod 222 are rotatably connected by a shaft 223. As the other end of the lateral section of the connecting rod 224 (e.g., the right end in Fig. 2B) is pushed, the connecting rod 224 is capable of turning about the shaft 223 to drive the upper furnace chamber 113 to move and open the upper furnace chamber 113 by a certain angle, thereby exposing the conveying space 120. After the upper furnace chamber 113 is opened, an operator may clean and maintain the interior space of the furnace chamber 112. After the upper furnace chamber 113 is opened, the overall height of the furnace chamber will be increased due to the increased height of the conveying space 120. Due to the overall height of the furnace chamber, comparing to providing the side elevations 140 respectively at the bottom of the upper furnace chamber sides 231 , providing the side elevations 140 respectively at the top of the pair of lower furnace chamber sides 232 can make it easier for the operator to clean and maintain the interior space of the furnace chamber 112 after the upper furnace chamber 113 is opened.

[0032] The gas curtain device 109 includes a pair of end barrier boxes 107 disposed oppositely in the height direction H of the furnace chamber 112. Each end barrier box 107 includes an air inlet 262 and a plurality of guide fins 261 , the end barrier box 107 being configured to direct gas entering the end barrier box 107 from the air inlet 262 to flow along each guide fin 261 . For example, an end barrier box 107a located in the upper furnace chamber 113 is configured to direct gas entering from the gas inlet 262 to flow downward along the guide fins 261 and an end barrier box 107b located in the lower furnace chamber 114 is configured to direct gas entering from the gas inlet 262 to flow upward along the guide fins 261 . As such, the gas flowing from the air inlet 262 can form a gas curtain capable of reducing the flow of air inside and outside the furnace chamber 112.

[0033] The exhaust device 154 is located outside the end barrier box 107a for drawing air out of the inlet end 151 and the outlet end 152 of the furnace chamber 112 such that negative pressure is generally able to be formed at the inlet end 151 and the outlet end 152 of the furnace chamber 112. As a result, the gas at the end barrier 108 generally flows from inside the furnace chamber to outside the furnace chamber, thereby better preventing external air from entering the furnace chamber 112. Moreover, after the gas inside the furnace chamber 112 flows outwards, it can also be extracted away by the exhaust device 154 in a timely manner, thereby substantially blocking the gas fluid communication between the internal and external environments of the furnace chamber 112. It should be noted that although only the specific structure of the end barrier 108 at the inlet end 151 of the furnace chamber 112 is shown in Fig. 2C, it can be understood by those skilled in the art that the end barrier 108 of the same structure is also provided at the outlet end 152 of the furnace chamber 112.

[0034] By providing the gas curtain device 109 and the exhaust device 154 of the end barrier 108, and further inputting an inert gas into the middle in the length direction L of the furnace chamber 112, the oxygen content in the gas within the furnace chamber 112 can basically be maintained to a certain range, and this is especially suitable for photovoltaic devices printed with certain slurry.

[0035] Fig. 3 is a schematic view showing a sintering furnace 380 including the furnace 100 shown in Fig. 1A. As shown in Fig. 3, the sintering furnace 380 includes a drying section 370, a sintering section 371 , and a cooling section 372, and the drying section 370, the sintering section 371 , and the cooling section 372 may be connected by the same conveying device 373 or by separate conveying devices. In the drying section 370, the organic matter or the like in the slurry printed on the photovoltaic device can volatilize. In the sintering section 371 , the electrode materials and silicon on the photovoltaic device are heated to a eutectic temperature, and the silicon atoms are dissolved in proportion into the electrode materials in a molten state. In the cooling section 372, the silicon atoms dissolved in the electrode materials are re-crystallized in a solid form such that an ohmic contact is formed between the electrode and the silicon, resulting in a solar cell. In the present example, the drying section 370 includes the furnace 100.

[0036] The drying section, sintering section and cooling section of existing sintering furnaces are generally monolithic structures. Due to the limitations of the frame structure, it is very difficult to increase the height of the conveying space of the furnace in the drying section individually. The present application makes certain modifications of the reflow furnace to obtain a furnace capable of drying upright photovoltaic devices, which is particularly suitable for drying sections of sintering furnaces, and can also be used for reflow soldering electronic components on circuit boards. [0037] Existing photovoltaic devices are generally sheet shaped, have a larger length and width, and have a smaller thickness. They are laid flat and carried on a conveyor belt for drying, with limited work efficiency. The furnace of the present application sets the height D1 of the processing element receiving space to be capable of accommodating the processing element when placed in an upright position, that is, the height D1 is set to be greater than or substantially equal to the maximum dimension of the length and width of the processing element. As such, the furnace of the present application can enable the processing element to be carried in an upright position on the conveyor belt and to be heated or cooled by the furnace chamber. The furnace of the present application is capable of handling more processing elements in a unit time with higher work efficiency at the same conveying speed and length, as compared with a furnace that generally lays processing elements flat on a conveyor belt.

[0038] Moreover, the furnace of the present application includes a plurality of heating units independently providing heat, and is capable of independently controlling the temperature for each heating unit such that the interior of the furnace chamber may have a richer temperature profile, thereby providing more possibilities for organic matter in the slurry printed on the photovoltaic device.

[0039] Furthermore, the furnace of the present application may also control the oxygen content in the gas inside the furnace chamber, depending on the specific needs, with particularly good effects on the removal of certain organic matter in the slurry.

[0040] The furnace of the present application may be adapted from a reflow furnace, and it is particularly suitable for drying sections of a sintering furnace in addition to maintaining its function of being used for reflow soldering electronic components on circuit boards.

[0041] Although the present disclosure has been described in connection with examples of the embodiments outlined above, various alternatives, modifications, variations, improvements, and/or substantial equivalents, whether known or foreseeable now or in the near future, may be apparent to those having at least ordinary skill in the art. In addition, the technical effects and/or technical problems described in the present specification are exemplary and not limiting; therefore, the disclosure in the present specification may be used to solve other technical problems and have other technical effects and/or may solve other technical problems.

Therefore, examples of embodiments of the present disclosure as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to include all known or earlier developed alternatives, modifications, variations, improvements and/or substantial equivalents.