KR20100054820A

KR20100054820A - Method for producing a solar cell

Info

Publication number: KR20100054820A
Application number: KR1020107004975A
Authority: KR
Inventors: 클라우스 메쯔너
Original assignee: 만쯔 아우토마티온 아게
Priority date: 2007-08-29
Filing date: 2008-08-27
Publication date: 2010-05-25
Also published as: KR101138097B1; WO2009030409A2; CN101803034A; EP2193548A2; WO2009030409A3; DE102007041057A1

Abstract

The invention relates to a method for producing a solar cell (10, 11) in which the solar cell (10, 11) is printed in multiple process steps using the screen printing method. In a first printing process, the solar cell (10, 11) is disposed in a first orientation relative to the printing direction (18) of a doctor and, in a second printing process, the solar cell is disposed in a different orientation relative to the printing direction. In this manner, the solar cell (10, 11) is always optimally aligned for printing oblong structures.

Description

Solar cell production method {METHOD FOR PRODUCING A SOLAR CELL}

The present invention relates to a method for producing a solar cell in which the solar cell is printed according to the screen printing method in a number of production steps.

It is known to print not only the front side but also the back side of the solar cell according to the screen printing method in production. In the prior art, the solar cell to be printed and the printing direction have a constant direction of fixed setting relative to each other.

Today, two types of printing units are used for screen printing: flat screen printing units and rotary screen printing units. In a flat screen printing unit, the printing direction generally indicates the direction of movement of the doctor on the substrate. In the rotary screen printing unit, the printing direction is defined by the conveying direction of the substrate.

An important criterion of screen printing is the screen release from the substrate after the doctor has moved over the screen, after the so-called screen jump.

The following discussion describes, in principle, the relationship by flat screen printing that also applies to rotary printing units.

Since the printing paste is a highly viscous liquid, the strong movement of the paper that initially restrains the screen on the substrate (solar cell) becomes active as the doctor moves over the area to be printed. Release can be through very strong tension of the screen. However, screen jumps require time depending on various printing parameters (dough, screen conditions, print images). The time required for screen jump is an important quantity. For this reason, it is common today to move the screen upwards (from the substrate) before the substrate is transported further, which favors screen jumps. The screen jump has proved to be difficult at all times if the printed image has to be printed over the full width of the object without disturbing, such as so-called fingers or bus bars for solar cells, for example full area back prints or conductor rails. . Each obstruction of the printing structure, such as each of numerous fingers or the like, during printing of the solar cell front, simplifies screen jump if they are printed in the direction of doctor movement.

The printing of bus bars and fingers for front contact, ie the printing of the solar cell front, constitutes the greatest technical challenge. Thus, if possible, the positioning of the solar cell for the direction of doctor movement or for orientation of the printing screen is optimally selected for this processing step. This means that the fingers of the front of the solar cell are printed in the direction of movement of the doctor. However, the bus bar on the solar cell back is directed transverse to the fingers of the solar cell front. If the solar cell is oriented to allow optimal printing of the solar cell front, this means that the printing of the solar cell backside occurs under poor conditions due to the precise alignment of the doctor movement with respect to the solar cell, This is because the entire width should be printed transverse to the direction of doctor movement without obstruction. This is where screen jumps are the most difficult and should be ensured through proper processing settings.

A possible solution is to run the wait time. However, this extends the printing cycle. Optionally, the screen may be moved upward at the end of printing. This also extends the printing cycle. It is also possible to increase screen tension. However, this shortens the life of the screen.

It is an object of the present invention to provide a method in which the printing cycle can be shortened and the life of the screen can be increased.

According to the invention, this object is achieved in the form mentioned at the outset, wherein at least the printing direction for the first printing operation and the solar cell are directed in a first direction with respect to each other and at least in another printing operation with a different orientation with respect to each other. The way is achieved in a very simple yet amazing way. Thus, the solar cell is aligned for at least one first printing operation in the first direction with respect to the doctor movement direction of the doctor or in the transport direction of the solar cell, and also has a different orientation with respect to the movement direction of the doctor or the transport direction of the solar cell. As is arranged for at least one other printing job. By this means, it is ensured that the solar cell is optimally aligned for the direction of doctor movement or transfer for all printing operations, preferably for rectangular printing structures; Most of the disadvantages of the above-described screen jump can be avoided. This means that the printing screen is exposed to low load and thus long term durability of the printing screen is achieved. In addition, the printing cycle is substantially shortened. The productivity of the plant in which the method is carried out is increased. In addition, the quality of each printing operation is improved. The advantages of this new method apply to flat screen printing units in the same way as rotary screen printing units.

By a particularly preferred method, the solar cell to be printed is rotated 90 ° before at least one printing operation. Because of this, the solar cell has a different orientation with respect to the doctor moving direction or the conveying direction when compared with the previous printing operation. Thus, the rectangular structure arranged to be orthogonal to the already printed structure may be applied in the same doctor movement direction or transport direction as the rectangular structure applied in the previous printing operation. In principle, it is also conceivable to use a second doctor having a 90 ° offset or 90 ° offset movement direction instead of rotating the solar cell 90 °. In each case, the solar cell according to the invention comprises different orientations with respect to the doctor moving direction or the conveying direction for two different printing operations.

If at least some rectangular structures in each printing operation are printed in the printing direction, ie in the direction of the doctor's movement or the solar cell's transport direction, another optimization for screen jump is obtained.

In this way, the current rail (bus bar) in the first printing operation can be printed at the rear of the solar cell with printing dough, for example silver paste or the like. This method is contrary to the known prior art, and the bus bars on the solar cell rear portion are oriented transverse to the direction of doctor movement, resulting in the disadvantages described above during screen jumps. By means of a flat screen printing unit, this means that during printing the doctor is moved in the stretching direction of the bus bar to be printed.

Further, in the second printing operation, the solar cell rear portion is well printed with printing dough, for example, aluminum dough, etc., and the printing direction becomes the stretching direction of the already printed bus bar. With a flat screen printing unit, this means that the doctor is moved in the stretching direction of the already printed bus bar. This means that the first and second printing operations are performed in the orientation of the solar cell with respect to the conveying direction or the doctor moving direction of the same remaining cell, corresponding to the printing direction.

In the third printing operation, the bus bars and the fingers are printed on the front of the solar cell with a printing dough, for example silver paste, etc., where the printing direction becomes the stretching direction of the finger to be printed. With a flat screen printing unit, this means that during printing the doctor is moved in the stretching direction of the finger to be printed. This ensures that very thin fingers are printed with optimum precision and operate without interference. It is also possible to initially print the solar cell front and then to print the solar cell back. In this case, the solar cell must be redirected to the direction of doctor movement following the printing of the solar cell front. Thus, the print-out of the "first to third printing job" may be related to the time sequence of the printing job, but this is not essential.

A special advantage can be obtained if the solar cell is gripped by the gripper and directed to the printing direction prior to at least one printing operation. As the gripper, a Bernoulli gripper may be preferably used. Prior to the third printing operation in which the solar cell front part is printed, the solar cell is rotated 90 ° by the gripper.

The productivity of the plant in which the method is performed can be increased if multiple solar cells can be printed simultaneously in at least one printing operation. Multiple solar cells are preferably printed simultaneously in all printing operations. This means that prior to at least one printing operation, a number of solar cells are redirected through the Bernoulli gripping.

Screen printing plants having a phage, preferably Bernoulli phage, for carrying out the method are also within the scope of the present invention. The screen printing plant may comprise a flat screen printing unit, where the printing direction corresponds to the doctor moving direction or the rotary screen printing unit, and the printing direction corresponds to the conveying direction of the substrate (solar cell).

Other objects, features and advantages of the present invention will be more clearly understood by the following detailed description with reference to the accompanying drawings.

1 is a plan view of a rear portion of two solar cells after a first printing operation.
2 is a plan view of the rear part of the two solar cells after the second printing operation.
3 is a plan view of the front portion of the solar cell after the third printing operation.

1 shows two solar cells 10, 11, the rear portions 12, 13 of which are shown. On its rear portions 12, 13 the solar cells 10, 11 each have so-called bus bars 14-17 which are printed simultaneously according to the screen printing method in the first printing operation. The printing direction, ie the doctor movement direction in the case of a flat screen printing unit or the conveying direction in the case of a rotary screen printing unit, is shown by an arrow 18. This means that bus bars 14 to 17 have been printed in the printing direction 18. This facilitates screen jumps. Silver batter printed bus bars 14-17 were produced.

Fig. 2 shows solar cells 10 and 11 on which aluminum pastes 19 and 20 are printed at the same time. The printing direction is shown by arrow 21. This means that the orientations of the printing directions 18, 21 and the solar cells 10, 11 are identical to the two printing operations.

3 shows a front view of the front portions 25, 26 of the solar cells 10, 11. Solar cells 10 and 11 were rotated 90 ° with respect to FIGS. 1 and 2. Thus, the fingers 27 and 28 can be applied in the printing direction 29 in the third printing operation, and the fingers 27 and 28 printed with silver paste are used for the bus bars 14 to 17 at the rear of the solar cell. 90 ° offset. The bus bars 30, 31 of the front portions 25, 26 are printed in the transverse direction in the printing direction 29 as in the third printing operation. Thus, the printing directions 18, 21, 29 are the same for all printing jobs. However, the orientation of the solar cells 10, 11 with respect to the printing direction 29 has been changed for printing of the solar cell fronts 25, 26.

10, 11: solar cells 14 to 17: bus bar
27, 28: fingered

Claims

In the solar cell production method in which the solar cells 10, 11 are printed according to the screen printing method in a plurality of production steps,
The printing directions 18, 21, 29 and the solar cells 10, 11 for at least one first printing operation are directed in a first orientation with respect to each other and in a different orientation with respect to each other in at least one other printing operation. Solar cell production method characterized by the above-mentioned.

The method of claim 1, wherein the solar cell to be printed (10, 11) is rotated 90 ° prior to at least one printing operation.

Method according to one of the preceding claims, characterized in that in each printing operation at least some rectangular structures are printed in the printing direction (18, 21, 29).

The conductor rail (bus bar) 14 to 17 in the first printing operation is printed on the solar cell rear portions 12 and 13, and the printing direction is the bus bar 14 to be printed. Solar cell production method characterized by being in the stretching direction of.

The solar cell rear portion 12, 13 is printed in the second printing operation, and the printing direction is the extension direction of the already printed bus bars 14 to 17. Battery production method.

In any one of the preceding claims, in the third printing operation the bus bars and fingers 27, 28 are printed on the solar cell fronts 25, 26, the printing direction of the fingers 27, 28 to be printed. A solar cell production method characterized by being in the stretching direction.

The solar cell according to any one of the preceding claims, characterized in that, prior to at least one printing operation, the solar cells 10, 11 are gripped with a gripper and aligned with respect to the printing directions 18, 21, 29. Production method.

Method according to any one of the preceding claims, characterized in that in at least one printing operation, a plurality of solar cells (10, 11) are printed simultaneously.

A screen printing plant, characterized by having a gripper for carrying out the method according to any one of the preceding claims.

10. The screen printing plant according to claim 9, wherein the printing unit is a flat screen printing unit, and the printing direction corresponds to the doctor moving direction.

10. The screen printing plant according to claim 9, wherein the printing unit is a rotary screen printing unit, and the printing direction corresponds to the transport direction of the solar cell.