Patent Application
20160322253
1. Field of the Invention
The present invention relates to a substrate carrier, and in particular to a substrate carrier for carrying and supporting solar cell substrates to perform wet etching in a manufacturing process, so as to form pyramid structure of superior quality on the surface of solar cell substrate, hereby raising the photo-electric conversion efficiency of the solar cells.
2. The Prior Arts
In the process of manufacturing solar cells, dry etching or wet etching is first performed, to form a pyramid structure on the surface of solar cell substrate, and that is used to produce a photo-electric conversion layer.
In general, in the process of manufacturing solar cells, a carrier is used to carry and support solar cell substrates. Then, a robotic arm is provided to hold the carrier, to go through a variety of processes relating to acid and alkali etching, rinsing, and drying steps for the solar cell substrates contained therein. In this process, the acid and alkali etching fluids may include the various strong acid and strong alkali etching such as potassium hydroxide, sodium hydroxide, sulphuric acid, nitric acid, hydrofluoric acid, and aqueous ammonia. The rinsing fluid may include highly purified fluid, and de-ionized water, to wash and clean the residue etching fluid remaining on the substrate. Finally, a drying step is performed to dry the substrate.
However, the material and the structure of the conventional carrier is not capable of withstanding strong acid and strong alkali etching fluids, and the high temperature incurred during such etching processes. In other words, the conventional carrier is not capable of withstanding strong acid and strong alkali, and it can only endure process temperature of about 60° C.˜80° C. As such, it can only withstand acid/alkali etching fluid of low concentration (<20%), such that its lifetime is reduced, and it has to be replaced after 100˜500 times of usage. In addition, hydrophobicity of the conventional carrier is rather insufficient, the residual etching fluid tends to remain around the solar cell substrate even after it has been rinsed, so after acid/alkali etching, the pin mark or invalid area around the solar cell substrate tends to be significantly large, so as to cause decrease of yield for the solar cells. For example, due to insufficient hydrophobicity of the conventional carrier, the residues of strong alkali etching fluid in the previous step may still remain on the substrate, even after through the rinsing process. As such, in case the substrates having strong alkali etching fluid residue thereon are transferred into the subsequent strong acid etching step, that could lead to acid-base neutralization, so as to adversely affect the result of substrate etching, and that could even endanger the life of the operator.
Therefore, the design and performance of a conventional substrate carrier is not quite satisfactory, and it leaves much room for improvement.
In view of the aforementioned problems and drawbacks of the prior art, the present invention provides a substrate carrier for solar cells, in order to overcome the shortcomings of the prior art.
A main objective of the present invention is to provide a substrate carrier for solar cells that is made of a specific material having superior hydrophobicity capability, so as to achieve the characteristics of high temperature resistance, erosion resistance, high cleanness, low pollution (or low particle release), high hydrophobicity, and high abrasion resistance, thus increasing the lifetime of the carrier itself significantly. In this way, in particular, when the carrier is used to perform wet etching, due to the superior hydrophobicity of the carrier, not only can the residue etching fluids be reduced by 20%˜80% in volume, but a superb pyramid structure can also be formed (an acute angle greater than 20° can be formed between the reflection surface of the pyramid structure and the surface of the substrate) on the surface of solar cell substrate, so as to raise the photo-electric conversion efficiency of the solar cells according to the invention.
In the prior art, for the solar cell made through using the conventional carrier, the pyramid structure formed on the substrate may have an acute angle of less than 20°, so that the photo-electric conversion efficiency of solar cell thus made is less than 16%. However, in the present invention, for the solar cell made by using this type of new carrier, the acute angle of the pyramid structure can be formed greater than 20°, so as to raise its photo-electric conversion efficiency of the solar cell to about 17%˜25%.
In pursuit of the objective mentioned above, the present invention provides a substrate carrier made of PFA for solar cells, comprising: two side plates; at least a side rod, connected respectively to an outer portion at each side of the two side plates; at least a bottom rod, connected respectively to a lower portion at each side of the two side plates; and at least a press rod, connected respectively to an upper portion at each side of the two side plates. There is a space formed by the two side plates, the at least a side rod, the at least a bottom rod, and the at least a press rod, such that the space may receive at least a solar cell substrate. There are a plurality of teeth arranged axially and equally spacing along axes of the side rod and the press rod, such that each of the teeth maintains a point-to-point contact with each solar cell substrate. A recess is provided on each side of the side plate to fasten a droplet projection for the press rod in a rotation way while an inclined opening is extended below the recess.
In the present invention, the carrier made of PFA (Tetrafluoroethylene-perfluoroalkyl Vinyl Ether Copolymer) is suitable for a wet chemical etching process, and the carrier is provided with the characteristics of high temperature resistance, erosion resistance, high cleanliness, low pollution, and abrasion resistance, and thus raising its lifetime significantly. Meanwhile, through the provision of the inclined openings, the carrier is designed to have good hydrophobicity, thereby effectively preventing residue of etching fluid from remaining around the solar cell substrate, and thus restricting the pin mark or ineffective area around the substrate to less than 1 mm2. In addition, a superb pyramid structure is formed on the surface of solar cell substrate, with the angle between the reflection surface and the bottom surface of the pyramid structure greater than 20°, and thus raising the photo-electric conversion efficiency of solar cells thus made significantly.
Further scope of the applicability of the present invention will become apparent from the detailed descriptions given hereinafter. However, it should be understood that the detailed descriptions and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed descriptions.
The related drawings in connection with the detailed descriptions of the present invention to be made later are described briefly as follows, in which:
The purpose, construction, features, functions and advantages of the present invention can be appreciated and understood more thoroughly through the following detailed description with reference to the attached drawings.
The present invention relates to a substrate carrier for solar cells. In the present invention, the term “radial” refers to a direction extending along the radius of a rod; while the term “axial” refers to a direction extending along an axis or lengthwise direction while passing through the center of the rod. As such, the “radial” (direction) and the “axial” (direction) are perpendicular to each other.
In general, the substrate carrier for solar cells is used in wet chemical etching process, to carry and support the substrate for the solar cells. In this way, the solar cell substrate 5 can be immersed into the high temperature and strong etching fluid (including but not limited to potassium hydroxide, sodium hydroxide, sulphuric acid, nitric acid, hydrofluoric acid, and aqueous ammonia), highly purified water or pure water, so as to perform repeated wet chemical etching and rinsing.
Refer to
Wherein, the two side plates 11 are located at the two ends of the carrier 1.
Two sides of the side rods 12 are each connected to the outer portion of each of the two side plates 11.
Two sides of the bottom rods 13 are each connected to the lower portion of each of the two side plates 11. A space 15 is formed by the two side plates 11, the side rods 12, and the bottom rods 13, so as to receive at least a solar cell substrate 5 in a carrier 1 for a wet chemical etching process.
Two sides of the press rod 14 are each connected to the upper portion of each of the two side plates 11.
In addition, a plurality of first teeth 16 are arranged axially and with equally spacing along the axis of the side rods 12 and the press rods 14, such that the solar cell substrates 5 can be put into the carrier 1, and be arranged between two adjacent first teeth 16. As such, as viewed in the top view cross section, each of the first teeth 16 and each of the solar cell substrates 5 are maintained in a point-to-point contact. In this way, during performing the wet chemical etching for the solar cell substrates 5, the shielded area during etching and rinsing is greatly reduced, so that the etching and rinsing process can be performed more thoroughly and completely, so as to provide good signal transmission, and improve the yield.
The upper portions of the two side plates 11 are each provided with a recess 111, to guidingly engage the droplet projections 141 of the press rods 14, and an inclined opening 1111 is extended outwardly from the recess 111 so as to provide high hydrophobicity through the inclined opening 111, thereby draining out effectively the residual etching fluid or rinsing fluid between the substrate and the carrier.
Summing up the above, through the PFA material of the carrier 1, in the wet chemical etching process, the carrier 1 could have the characteristics of high temperature endurance, erosion resistance, high cleanliness, low pollution or low particle release, and abrasion resistance, so as to increase the lifetime of the carrier 1 significantly. Moreover, with the provision of the inclined opening 1111, the carrier 1 is able to have high hydrophobicity, so as to prevent the residual chemical etching fluid from remaining around the solar cell substrate 5, thus reducing pin mark or invalid regions around the substrate 5. Besides, it could cause the photo-electric conversion layer of the solar cell substrate to form a well-defined pyramid structure, such that the acute angle formed on the reflection surface of the pyramid structure along the horizontal surface of the substrate is greater than 20°, hereby raising the anti reflection efficiency of the photo-electric conversion layer, and its photo-electric conversion efficiency to exceed over 17%.
Refer to
Moreover, in the first embodiment, in the side view of the first teeth 16 is shown as an asymmetry fin. The radius of curvature of the arc edge R is between 3 mm and 500 mm. An angle θ1, formed between the first line L1 passing through the apex P and the junction J, and the second line L2 passing through the apex P and the center of the rod O, is between 10° and 85°; while an angle θ2, formed between the line edge L and the second line L2, is 18°˜45°. Through the design of the size and angle of the structure mentioned above, the carrier is able to have optimal hydrophobicity, so that the solar cells thus produced could achieve the highest photo-electric conversion efficiency.
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In the present embodiment, the plurality of first teeth 16 and the plurality of second teeth 17 are arranged axially in a staggered arrangement. The first teeth 16 and the second teeth 17 are designed to have similar shape and structure, so that the solar cell substrates 5 can be placed into the space 15 of the carrier 1 to prevent adhesion of substrates to teeth within the carrier. When the wet chemical etching is performed, the shape and structure of the first teeth 16 and the second teeth 17 can be adjusted based on the fluid flow direction, speed in the various acid-alkali tanks, or acid alkali fluid, temperature, concentration in the various acid-alkali tanks.
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In a second embodiment of the present invention, as shown in
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In a fourth embodiment of the present invention, as shown in
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As the droplet projection 141 of the press rod 14 is extended inwardly to form a round protrusion 143, such that when the press rod 14 is positioned and guided in the recess 111 of the side plate 11, the round protrusion 143 is pressed or abutted tightly against the inner portion of the side plate 11, so as to prevent the press rod 14 from the left or right shifting due to being pressed by the substrate, thus adversely affecting the positioning of press rod 14 in the side plate 11.
When the press rod 14 is guidingly positioned in the recess 111 of the side plate 11, the first teeth 16 disposed on the press rod 14 are faced toward and pressed against the upper portion of the solar cell substrate 5.
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As mentioned above, the recess 111 of the side plate 11 is further provided with the U-shape notch 1115 corresponding to the major axis and the minor axis. A slant face 1110 is respectively disposed on both left and right entry sides of the U-shape notch 1115 for engagement with the press rod 14. Wherein, on each of both sides of the bottom end of the U-shape notch 1115, it is provided respectively with a first diameter arc portion 1116 and a second diameter arc portion 1117 to restrict the movement of the major axis and the minor axis of the droplet projection 141. As such, when the first diameter arc portion 1116 and the second diameter arc portion 1117 are different, the press rod 14 is allowed to rotate only in a specific direction (clockwise or counter clockwise) for a specific distance. When the first diameter arc portion 1116 and the second diameter arc portion 1117 are the same, the press rod 14 is allowed to have a clockwise or counter clockwise rotation for a specific distance. Therefore, regardless if the diameters of the first diameter arc portion 1116 and the second diameter arc portion 1117 are equal, the press rod can be rotatably positioned in the recess of the side plate.
Refer to
The positions of connecting the side plates 11 with the side rods 12 and with the bottom rods 13 are provided with a connecting and melting place (not shown), and in each of the connecting and melting places is provided with a connecting and melting portion (not shown). Through the connecting and melting portions, the ends of the side rods 12 and bottom rods 13 are connected and melted to the connecting and melting portions of the side plates 11.
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Compared with the prior art, in accordance with the present invention, the parameters for experiment are measured as follows: the carrier 1 is used to carry 156 mm×156 mm solar cell substrates (silicon-based wafer substrate), to put into an etching machine, at experiment temperature of 85° C.˜95° C., with the etching fluid of hydrogen fluoride (HF), hydrochloric acid (HCL), and Potassium hydroxide (KOH).
Refer again to
Above the retraction section 115 of the side plate 11 is further disposed a RFID tag (not shown), in which the related data of solar cell substrate 5 is recorded (for example, type of substrate, customer name, manufacturing method . . . etc), so as to facilitate the manufacturing follow-up process of the carrier 1.
In the present invention, the manufacturing method for making solar cell substrate includes the following steps:
Firstly, providing a carrier 1, so as to receive and carry a plurality of solar cell substrates 5.
Next, transporting the carrier 1 to go through a wet etching process, so as to perform etching of the solar cell substrates 5;
Then, transporting the carrier 1 to go through a rinsing process, so as to rinse the etching fluid on the carrier 1 and the solar cell substrates 5, to obtain the finished product of the solar cell substrates 5; and
Finally, transporting the carrier 1 to go through a drying process, so as to dry the solar cell substrates 5.
Wherein, the design and structure of the carrier 1 are described in the embodiments mentioned above.
The wet etching process is performed in an operation temperature 85° C.˜95° C. The etching fluid is selected from one in a group consisting of: hydrogen fluoride (HF), hydrochloric acid (HCL), and Potassium hydroxide (KOH). The dimension of the solar cell substrate is 156 mm×156 mm in length and width respectively.
Refer again to
Through the material and features of the carrier 1 (as shown in Table 1), the carrier 1 used in the wet chemical etching process is provided to have the characteristics of high temperature resistance, erosion resistance, high cleanliness, low pollution (or low particle release), and abrasion resistance (as shown in Table 2), thus increasing its lifetime significantly.
When the solar cell substrates are placed in the carrier of the present invention to perform wet etching, through the superior hydrophobicity of the carrier, the residual etching fluid can be greatly reduced in volume by 20%˜80%. Further, a superior pyramid structure can be well-formed on the surface of the solar cell substrate, such that the acute angle formed between the reflection surface of the pyramid and the surface of the substrate can be greater than 20°, so as to raise the photo-electric conversion efficiency of the solar cell to 17%˜25%.
The size of the solar cell substrate (such as silicon wafer) can be set at the dimension: 156 mm×156 mm. The temperature of the etching tank is set at 85° C.˜95° C., while the etching fluids in the etching tank include etching fluids of HF, HCL, KOH. Through the improved hydrophobicity of the carrier, the solar cell substrates can thus be obtained, and the invalid region (pin mark) on each solar substrate can be reduced to less than 1 mm2 as verified by the aforementioned tests and experiments.
In addition, the guide slant face is provided respectively at the corner of the side plate and in the positioning hole in which a guiding angle is provided in a range of 10°˜80°, thus leading to excellent hydrophobicity. As such, it is able to avoid the residual etching fluid and rinsing fluid remaining around the solar cell substrate, hereby reducing the invalid region (pin mark) around the solar cell substrate to less than 1 mm2.
In contrast, for the conventional carrier, the acid-alkali etching fluid tends to remain around the carrier, so as to cause the invalid region (pin mark) for the solar cell to be around 1˜10 mm2. As such, not only the yield of the solar cells thus produced is decreased, but its photo-electric conversion efficiency is also reduced to less than 16%.
Moreover, in the present invention, the carrier is made to have a structure of better hydrophobicity, together with proper adjustment of the material features (as shown in Table 1), residual etching fluid and rinsing fluid remaining on the substrate can be reduced in volume by 20%˜80%. Also, in the drying process of the solar cell substrates, the drying speed can be raised by more than 12.5%. In other words, compared with the Prior Art, the drying time can thus be reduced by 12.5%.
In the present invention, the carrier is made into a structure of better hydrophobicity, that includes but is not limited to the following structure characteristics: the point-to-point contact structure for the teeth and solar cell substrates; the angle formed in the teeth, its radial/axial size and structure; side plate and the guide slant face of the positioning hole, to achieve any of the functions and effects or their combinations as shown in Table 2. In addition, though as shown in
The above detailed description of the preferred embodiment is intended to describe more clearly the characteristics and spirit of the present invention. However, the preferred embodiments disclosed above are not intended to be any restrictions to the scope of the present invention. Conversely, its purpose is to include the various changes and equivalent arrangements which are within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 104206680 | Apr 2015 | TW | national |
