JP4046492B2 - Solar cell manufacturing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a production equipment of the solar cell, in particular, a metal conveyor belt for carrying the wafer in a heating furnace and the heating furnace for drying and firing process on the coated electrode paste on the wafer those concerning the manufacturing equipment of the solar cell having.
[0002]
[Prior art]
Conventionally, a conductive electrode paste is applied to the front and back surfaces of a wafer to be a solar cell by printing or the like in order to increase the power generation efficiency of the solar cell or to efficiently extract electricity generated by the solar cell. A manufacturing method for performing a drying and firing process is known. FIG. 8 is a cross-sectional view schematically showing a general configuration of a solar battery cell manufactured by such a method. That is, the solar cell 1 includes a polycrystalline wafer 2 as a semiconductor substrate, a surface electrode 3 formed on the surface of the wafer 2, and a back electrode 4 formed on the back surface of the wafer 2.
[0003]
The wafer 2 is formed by solidifying p-type silicon, and an n ⁺ layer 5 is formed on the surface thereof to form a pn junction. Irregularities 6 for promoting the absorption of sunlight are formed on the surface of the n ⁺ layer 5, and an antireflection film 7 for preventing the reflection of sunlight is further formed on the surface of the irregularities 6. Has been. A p ⁺ layer 8 is formed on the back surface of the wafer 2.
[0004]
The irregularities 6 are formed by performing dry etching on the wafer 2 using a chlorine gas such as chlorine trifluoride gas (CClF ₃ ). Alternatively, it is formed by performing wet etching using an alkaline aqueous solution such as an aqueous sodium hydroxide solution (NaOH). The antireflection film 7 is made of a silicon nitride film formed by a plasma CVD method using a mixed gas of silane and ammonia as a raw material, or a titanium oxide film formed by a normal pressure CVD method using a titanic acid alkoxide as a raw material.
[0005]
The surface electrode 3 is formed by applying an Ag paste to the light receiving surface of the wafer 2 and firing it. Similarly, the back electrode 4 is coated with an aluminum metal paste and fired at about 700 ° C. to form the p ⁺ layer 8. Then, the Ag paste is applied to a part of the back surface and fired. Formed. Then, the solar battery cell 1 is completed by dipping in a solder bath (not shown) and soldering the portions 3 and 4 where the Ag paste is applied and fired.
[0006]
In a manufacturing apparatus for performing such a method for manufacturing a solar battery cell, an Ag paste and / or aluminum (Al) applied to the front surface and / or back surface of the wafer 2 to form the front electrode 3 and / or the back electrode 4. ) A belt-type conveying means and a heating furnace are used in the paste drying / firing process. Conventionally, the wafer 2 coated with Ag paste and / or aluminum (Al) paste is as shown in FIG. It was placed directly on a mesh-shaped metal transport belt (mesh belt) 9 that enters and exits a heating furnace (not shown).
[0007]
[Problems to be solved by the invention]
In the conventional technique described above, paste that has not yet been dried adheres to the conveyor belt 9, the components of the paste are transferred to the conveyor belt 9, and the metal portion of the conveyor belt 9 is alloyed, thereby reducing the life of the conveyor belt 9. There was a problem of a significant decrease.
[0008]
In addition, the portion of the wafer 2 that is in direct contact with the conveyor belt 9 has a temperature increase rate different from that of the portion that is not in contact with the conveyor belt 9, so that the Al paste is peeled off and blistered after drying and baking. There was a problem.
[0009]
In addition, when the conveyor belt 9 is soiled by the paste adhered in the previous drying / baking process, the appearance of the conveyor belt 9 is marked on the surface of the completed solar battery cell 1, and the appearance is remarkably impaired. The wafer 2 is contaminated, and the characteristics of the completed solar battery cell 1 may be deteriorated.
[0010]
An object of the present invention is to eliminate a decrease in the life of a conveyor belt and a decrease in the quality of a solar battery cell caused by the electrode paste applied to a wafer adhering to a metal conveyor belt of a solar battery manufacturing apparatus. It was made as.
[0011]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention carries a wafer coated with an electrode paste into a heating furnace with a metal conveying belt, and dries the electrode paste applied to the wafer with the heating furnace. -In a solar cell manufacturing apparatus that performs a firing process, a wafer is supported on a conveyor belt so as not to contact the conveyor belt, and multiple types of wafers having different dimensions can be supported and impact applied to the supported wafer. Support means formed so as to relax the support means , the support means is composed of a plurality of support members provided at a predetermined interval on the conveyor belt, and each support member is located between adjacent support members. The support members are each provided with a plurality of support portions .
[0012]
According to such a configuration, the non-dried electrode paste applied to the wafer does not adhere to the transport belt, and therefore it is possible to prevent the metal portion of the transport belt from alloying and shortening the life. In addition, since the electrode paste does not adhere to the transport belt, it is possible to prevent the production of solar cells whose appearance is impaired or solar cells whose characteristics are deteriorated due to wafer contamination. In addition, since the conveyor belt does not contact the wafer, the heating rate of the wafer to be dried and baked can be made uniform over the whole, and the peeling and blistering of the paste after drying and baking are prevented. be able to. In addition, since it is possible to deal with a plurality of types of wafers without replacing the support means, labor is reduced. In addition, shocks such as vibration of the conveyor belt during the drying / baking process are not easily transmitted to the wafer, so that defective products are less likely to be generated and the production yield is improved.
[0014]
Further, according to the present invention, in the configuration described above , the wafer supported between the plurality of supporting members by the movement of the conveying belt is introduced from the supporting member in the vicinity of the wafer discharge side end of the conveying belt. It is characterized by a shooter to be detached.
[0015]
In this case, since the dried and baked wafer can be automatically and efficiently detached from the support member, the manufacturing efficiency is improved.
[0018]
Moreover, the present invention is characterized in that, in any of the above-described configurations , the support means is detachable from the transport belt.
[0019]
In this case, when the support means is damaged, it is only necessary to replace the support means, so that maintenance is facilitated. Further, by replacing the support means with another type, it is possible to deal with various types of wafers.
[0022]
In any one of the configurations described above , the present invention is characterized in that a member having cushioning properties is attached to a portion of the support means that receives the wafer.
[0023]
In this case, defects such as cracking of the wafer due to impact such as vibration of the conveyor belt during the drying / baking process hardly occur and the production yield is improved.
[0024]
Moreover, the present invention is characterized in that, in any of the above-described configurations , the portion of the supporting means that receives the wafer is formed of a flexible material.
[0025]
In this case, defects such as cracking of the wafer due to impact such as vibration of the conveyor belt during the drying / baking process hardly occur and the production yield is improved.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view of a main part of a solar cell manufacturing apparatus according to an embodiment of the present invention. FIG. 2 shows a wafer supported by a support member attached to a conveyor belt of the manufacturing apparatus of FIG. FIG. 3 is a front sectional view showing the attachment relationship between the support member and the conveyor belt, FIG. 4 is a side view showing the attachment relationship between the support member and the conveyor belt, and FIG. 5 is the support member and the conveyor belt. It is a top view which shows the attachment relationship of. In the present embodiment, the same reference numerals are given to portions corresponding to those of the prior art, and duplicate descriptions are omitted.
[0028]
In FIG. 1, reference numeral 10 denotes a tunnel-shaped heating furnace, and a mesh-shaped metal conveyance belt 9 advances in the direction of the arrow and enters and exits the heating furnace 10. As shown in FIG. 2, a plurality of support members (support means) 11, 11,... That support the wafer 2 are aligned on the transport belt 9 at regular intervals in the traveling direction and the width direction. It is provided as follows. Each support member 11 supports the wafer 2 between the other three adjacent support members 11, and the wafer 2 is not in contact with the transport belt 9.
[0029]
As shown in FIG. 1, a plurality of heaters 23, 23,... Are disposed in the heating furnace 10 so as to face the upper and lower surfaces of the wafer 2 on the support member 11. Are provided at predetermined intervals. In addition, a fork-shaped shooter 24 is provided in the vicinity of the discharge side end of the wafer 2 on the transport belt 9 so as to enter the space between the support members 11 and 11 as the transport belt 9 moves and separate the wafer 2 from the support member 11. The shooter 24 automatically and efficiently removes the wafer 2 from the support member 11 without receiving an impact and guides it to the next process.
[0030]
The support member 11 is formed by bending a thin metal strip having elasticity, and has a protrusion 12 that protrudes upward at the center and extends in the traveling direction of the conveyor belt 9 as shown in FIG. The left and right sides are formed in steps so as to support two types of wafers 2 and 2 '.
[0031]
That is, on both the left and right sides of the protrusion 12, a first support portion 13 that extends from the lower end portion of the protrusion 12 toward the outer side and the lower side in the width direction of the conveyor belt 9, and a first vertical portion that extends vertically downward from the lower end portion. Part 14, a second support part 15 extending from the lower end part toward the outside in the width direction of the conveyor belt 9 and downward, and a "<" shape from the lower end part toward the inside in the width direction of the conveyor belt 9 or On the other hand, a bent portion 16 bent into an inverted “<” shape, a second vertical portion 17 extending vertically downward from the lower end portion thereof, and a claw portion extending from the lower end portion toward the outer side in the width direction of the conveyor belt 9. 18 and 18 are formed symmetrically.
[0032]
The bent portions 16 and 16 have a function as a stress relief that absorbs an impact applied to the wafer 2 or 2 ′ supported by the first support portion 13 or the second support portion 15 during transfer or take-out. is doing. Therefore, the vibration of the conveyor belt 9 during drying / firing is hardly transmitted directly to the wafers 2 and 2 ′, and stress that causes cracking of the wafers 2 and 2 ′ is reduced.
[0033]
The support member 11 is detachably engaged with an attachment member 19 attached to the transport belt 9. The attachment member 19 is formed by bending a thin metal strip having elasticity, and has curled bent portions 20 at both ends, and the claw portions 18 and 18 of the support member 11 are provided at the bent portion 20. Are to be engaged. In addition, the part between the bending parts 20 and 20 in the attachment member 19 is flat form. The attachment member 19 is inserted and mounted between an upper wire 21 and a lower wire 22 that form the transport belt 9.
[0034]
A method of attaching the support member 11 to the attachment member 19 will be described. The second vertical portions 17 and 17 of the support member 11 are pushed and bent inward, and the support member 11 is bent and the bent portions 20 and 20 of the attachment member 19. Is inserted between the wires 21 and 21 in contact with each other, and the tip portions of the claw portions 18 and 18 are inserted into the bent portion 20 of the mounting member 19 to release the pressing force. As a result, the tip portions of the claw portions 18 and 18 are elastically pressed against the inner surfaces of the bent portions 20 and 20, and the support member 11 is fixed on the attachment member 19. That is, the support member 11 is fixed to the transport belt 9 in the traveling direction, the width direction, and the vertical direction (see FIGS. 4 and 5).
[0035]
A portion between the bent portions 20 and 20 of the attachment member 19 is supported by three or more wires 22, and the wafers 2 and 2 ′ supported on the support member 11 are kept horizontal. Thereby, since the wafers 2 and 2 ′ do not hit an object outside the transfer path during transfer, transfer errors can be reduced. Further, since the distance from the heaters 23, 23,... To each part of the wafers 2, 2 ′ is kept constant, the entire wafers 2, 2 ′ are uniformly dried and baked. The support member 11 and the attachment member 19 are formed as small as possible so that the temperature rise characteristics of the heating furnace do not deteriorate.
[0036]
Next, another embodiment of the present invention will be described. 6 and 7 are front sectional views showing the attachment relationship between the support member and the conveyor belt according to another embodiment of the present invention. Note that, in the present embodiment, the same reference numerals are given to the portions corresponding to the above-described embodiments, and duplicate descriptions are omitted.
[0037]
Since the support member 11 is usually made of a hard metal material that is durable at high temperatures (for example, SUS304, Nichrome V, etc.), even if the bent portions 16 and 16 are provided to provide a function as a stress relief. When the wafers 2, 2 ′ jump up on the hard support member 11 and collide with the support member 11 due to the vibration of the conveyor belt 9 during drying / firing, there is a possibility that the wafers 2, 2 ′ may crack.
[0038]
Therefore, the support member 11 ′ shown in FIG. 6 is formed of a hard metal material as described above, and the first and second support portions 13 and 15 that receive the wafers 2 and 2 ′ and the protrusions 12 are thin. A wire 25 is wound in a coil shape. By doing so, even if the wafers 2 and 2 'spring up on the hard support member 11' due to vibration of the conveyor belt 9 during drying and baking, the wafers 2 and 2 'are broken because the wire 25 acts as a cushion. There is no. In place of the wire 25, a fine mesh net made of SUS or the like may be wound around the support member 11. Other configurations of the present embodiment are the same as those of the first embodiment.
[0039]
Further, the supporting member 11 '' shown in FIG. 7 is a heat-resistant resin having a flexible portion such as Teflon (registered trademark) in which the first and second supporting portions 13 and 15 that receive the wafers 2 and 2 'and the protrusions 12 are provided. The lower portion is formed so as to have a plate-like portion 27 on which the heat-resistant resin 26 is placed by a plate material made of a hard metal material as described above. Even in this case, when the wafers 2, 2 ′ placed on the heat-resistant resin 26 jump up, the wafers 2, 2 ′ are not broken. Other configurations of the present embodiment are the same as those of the first embodiment. This support member is mainly used in the drying step in consideration of its heat resistance.
[0040]
【The invention's effect】
As described above, according to the present invention, since the support means for supporting the wafer so as not to contact the conveyance belt is provided on the conveyance belt, the electrode paste which is not dried does not adhere to the conveyance belt. It is possible to prevent the metal portion of the belt from alloying and reducing the life. In addition, since the electrode paste does not adhere to the transport belt, it is possible to prevent the production of solar cells whose appearance is impaired or solar cells whose characteristics are deteriorated due to wafer contamination. In addition, since the transfer belt does not contact the wafer, the heating rate of the dried and baked wafer can be made uniform over the whole, and the peeling and blistering of the paste after drying and baking are prevented. Can do. Further, since the plurality of types of wafers having different dimensions can be supported, the plurality of types of wafers can be dealt with without replacing the support means, thereby reducing labor. In addition, because it is designed to mitigate the impact on the supported wafer, it is difficult for shocks such as the vibration of the conveyor belt during the drying / firing process to be transmitted to the wafer, so that defective products are less likely to be produced and produced. Yield is improved.
[0041]
In the vicinity of the discharge side end portion of the wafer in the conveyance belt, a chute of separating the wafer supported between them enters between a plurality of support members according to the movement of the conveyor belt from the support member is provided As a result, the dried and baked wafer can be automatically and efficiently detached from the support member, thereby improving the manufacturing efficiency.
[0043]
Also, by supporting lifting means is detachably attached to the conveyor belt, when the support means is broken, since it is only replaces take support means, which facilitates maintenance. Further, by replacing the support means with another type, it is possible to deal with various types of wafers.
[0045]
Further, by the member having a portion cushioning undergoing wafer in supporting lifting means attached, such as cracking of the wafer due to impact such as vibration of the conveyor belt in the drying and baking process failure almost not occur, production Yield is improved.
[0046]
Also, by the part which receives the wafer in the supporting lifting means is formed of a material having flexibility, no longer poor little occurrence of cracks in the wafer due to impact such as vibration of the conveyor belt in the drying and firing process, production Yield is improved.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a main part of a solar cell manufacturing apparatus according to an embodiment of the present invention.
2 is a plan view showing a state in which a wafer is supported on a support member attached to a conveyor belt of the manufacturing apparatus of FIG. 1;
FIG. 3 is a front sectional view showing a mounting relationship between a support member and a conveyor belt.
FIG. 4 is a side view showing a mounting relationship between a support member and a conveyor belt.
FIG. 5 is a plan view showing a mounting relationship between a support member and a conveyor belt.
FIG. 6 is a front sectional view showing a mounting relationship between a support member and a conveyor belt according to another embodiment.
FIG. 7 is a front sectional view showing a mounting relationship between a support member and a conveyor belt according to another embodiment.
FIG. 8 is a cross-sectional view schematically showing the structure of a general solar battery cell.
FIG. 9 is a plan view showing a state in which a wafer is supported on a conveyor belt of a conventional solar cell manufacturing apparatus.
[Explanation of symbols]
2 Wafer 9 Transport belt 10 Heating furnace 11 Support member (support means)
24 Shuta

Claims (5)

In the solar cell manufacturing apparatus, the wafer coated with the electrode paste is carried into a heating furnace by a metal conveyance belt, and the electrode paste applied to the wafer is dried and fired by the heating furnace.
Provided on the conveyor belt is a support means configured to support the wafer so as not to contact the conveyor belt, to support a plurality of types of wafers having different dimensions, and to reduce the impact applied to the supported wafer. ,
The support means is composed of a plurality of support members provided at predetermined intervals on the transport belt, and each support member is formed to support the wafer between adjacent support members. A solar cell manufacturing apparatus comprising a plurality of support portions . A shooter is provided in the vicinity of the discharge side end of the wafer on the transfer belt so as to enter between the plurality of support members according to the movement of the transfer belt and to release the wafer supported between them from the support member. The solar cell manufacturing apparatus according to claim 1 . The solar cell manufacturing apparatus according to claim 1 or 2 , wherein the support means is detachably attached to the transport belt. The solar cell manufacturing apparatus according to any one of claims 1 to 3 , wherein a member having cushioning properties is attached to a portion of the support means that receives the wafer. The solar cell manufacturing apparatus according to any one of claims 1 to 4 , wherein a portion for receiving the wafer in the supporting means is formed of a flexible material.

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