JPH04181782A - Rear electrode of solar cell and the method of connecting lead wire to said electrode - Google Patents

Abstract

PURPOSE:To make it possible to connect lead wires adequately by arranging a main electrode comprising an Al film formed on the opposite side of a light- receiving surface and a group of auxiliary electrodes formed on the main electrode surface and having projected portions in one direction. CONSTITUTION:When solar cells 10 having rear electrodes are immersed into a solder solution 16 in a solder bath 15 and then raised above the solution, the solder will be coated on the surface of an auxiliary electrode 12, thereby forming a thin solder coat layer 23. At the same time, the solder solution flows to the tip portion and a solder rich portion 17 is formed at the projected portion at the tip of each auxiliary electrode 12. In this case, by providing the same shape for the auxiliary electrode 12, the height of the solder rich portion 17 from the main electrode face can be made the same. Thus, by soldering a lead wire 25 to the solder rich portion 17, the lead wire can be connected fairly good. By doing this, the solder rich portions can be uniformly made and the soldering of lead wire can be made fairly good.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a back electrode of a solar cell and a method of connecting lead wires to the electrode.

=Prior Art] The formation of electrodes of a conventional solar cell will be explained with reference to FIGS. 5 to 7.

On the light-receiving side of the solar cell, the substrate is heated to 800 to 900°C in a phosphine (PH) gas atmosphere to diffuse the 0 layer 31 into the p-type S1 substrate 30 to form a p-n junction as shown in FIG. Form.

Next, as shown in Figure 7, etc., ohmic B is placed on the back side.
Print All' paste for S F (Back 5 surface Field) on the entire surface and make I00''CJ:J
After drying at a lower temperature, it is fired at 700-800°C.

Next, as shown in FIG. 6, auxiliary electrodes 33 and fine electrodes 34 are printed with Ag paste on the front surface and dried at 100° C. or less, and then auxiliary electrodes 37 and 34 are printed with Ag paste on the back surface as shown in FIG. Either print the fine electrode 38 and dry it at 100°C or less, or conversely, print the auxiliary electrode 37 and the fine electrode 38 on the back side using Δg base, dry it, and then apply the auxiliary electrode 33 and the fine electrode 34 on the front side with Ag paste. Print and dry. After drying the Ag paste, it is fired at 600 to 700°C.

When the solar cell circuit board with the collector electrode formed thereon is dipped in solder for 1 to 2 seconds, the solder liquid is repelled from the surface of the board, and the solder is coated only on the Ag paste.
After the extraction electrode is formed, the electrode formation of the solar cell is completed as shown in FIG. 7(a).

Problems to be solved by the invention = As described above, the back electrode of a conventional solar cell is formed by printing a thin electrode and an auxiliary electrode on a main electrode consisting of an AI anode.
Thereafter, back electrodes were formed by solder dipping, but solder bridges were formed between the thin electrodes, causing problems in connecting lead wires in subsequent processes. Also,
There was a problem in that solder balls formed and were damaged during the lamination stage.

The present invention is intended to solve the above-mentioned problems, and includes a back electrode of a solar N pond, which can uniformly form solder for connecting lead wires on the back surface, and can perform lead wire connections well. The purpose is to provide a method for connecting lead wires to electrodes.

[Means for solving the problem: To this end, the present invention provides a main electrode made of an Al film formed on the surface opposite to the light-receiving surface, and a main electrode formed on the main electrode surface that is convex in one direction. Solder-dip the back electrode of the solar cell consisting of the auxiliary electrode group and the convex part of the auxiliary electrode facing downward, and solder the lead wire to the solder rich part formed on the part of the convex part. The present invention is characterized by a lead wire connection method characterized by the following.

[Effect]

The present invention provides a solar cell substrate having an arrow-shaped or Y-shaped auxiliary electrode group having a convex portion in the - direction on the main electrode surface formed on the back surface, with the convex portion of the auxiliary electrode facing downward. When the board was pulled up, the solder liquid flowed along the auxiliary electrode surface and a solder-rich part was formed on the convex part of the electrode tip, so that the solder-rich part was exposed to sunlight. It is formed almost uniformly on the back side of the pond, and by soldering the lead wire to the solder-rich part,
It is possible to attach the lead wires properly.

[Example 2 Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing one embodiment of the back electrode of a solar cell according to the present invention. In the figure, IO is a solar cell, 11 is a main electrode, and I2 is an auxiliary electrode.

On the back side of the solar cell 10, l paste is printed on the entire surface in advance, and after drying at a temperature of 100"C or less,
℃ to form the main electrode ``11.'' After printing Ag paste on the surface of the main electrode 11 and drying at 100 ℃ or less, auxiliary electrode 12 is formed by baking at 600 to 700 ℃. do. The auxiliary electrode 12 is a patterned electrode having a uniform radius, and has an arrow-like shape with a convex portion in one direction. In the illustrated example, two rows of such arrow-shaped electrodes are formed, Each arrow-shaped electrode is formed separately.

As shown in FIG. 2, the solar cell 10 with the back electrode formed thereon is immersed in a solder bath 15 filled with solder liquid 1B with the arrow pointing downwards. The solder flows along the auxiliary electrode surface and collects at the tip, forming a solder rich 817 as shown in FIG.

FIG. 4 is a sectional view taken along the line A-A in FIG. 3, and as shown in the figure, the solder is coated on the surface of the auxiliary electrode 2 to form a thin solder coat layer 23, and the solder liquid is applied to the tip. The solder-rich portions 17 are formed on the protrusions at the tips of each auxiliary electrode 12. In this case, by making the shapes of the auxiliary electrodes j2 the same, the heights of the solder rich portions 17 from the main electrode surface can be made uniform. Therefore, by soldering the lead wire 25 to the solder rich portion 17, the lead wire can be connected very well. Further, the solder rich portions 17 to which lead wires are attached can be distributed according to the distribution of the auxiliary electrodes.

In the above embodiment, the arrow-shaped electrodes are separated from each other so that the solder-rich portion 17 is formed at the tip of each electrode, but it is not necessary to separate them all, and they may be continuous with each other. In addition, the electrode is not limited to an arrow-shaped electrode, but any shape can be used as long as it has a convex portion in one direction and a solder-rich portion is formed, such as a Y-shaped electrode. be.

Effects of the Invention As described above, according to the present invention, it is possible to form only the auxiliary electrode with a uniform width on the main electrode surface, form a uniform pre-solder latch portion, and reduce the soldering of lead wires. It becomes possible to perform it well.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing one embodiment of the solar cell back electrode of the present invention, Fig. 2 is a schematic diagram illustrating solder dipping of the solar cell substrate, and Fig. 3 is a diagram showing the solder formed on the protrusion of the auxiliary electrode. FIG. 4 is a diagram showing a rich portion, FIG. 4 is a diagram for explaining lead wire connection, and FIGS. 5, 6, and 7 are diagrams for explaining conventional back electrode formation. DESCRIPTION OF SYMBOLS 10... Solar cell, 11... Main electrode, 12... Auxiliary electrode, 17 Solder rich part, 23... Solder coat layer,
25... Lead wire. Requester Tonen Co., Ltd. Patent Attorney Jji Akira (7 others) Figure 1 Figure 2 Figure 3 Figure 4

Claims (4)

[Claims] (1) A solar cell back electrode consisting of a main electrode made of an Al film formed on the surface opposite to the light-receiving surface, and an auxiliary electrode group formed on the main electrode surface and having a convex portion in one direction. (2) The auxiliary electrode group is a solar cell back electrode consisting of arrow-shaped or Y-shaped auxiliary electrodes. (3) The solar cell back electrode according to claim 1 or 2, wherein the auxiliary electrode groups are separated from each other. (4) A solar cell substrate having a back electrode according to any one of claims 1 to 3 is solder-dipped with the convex portion facing downward, and a solder rich layer is formed on the convex portion. A lead wire connection method characterized in that the lead wire is soldered to the part.