JP5858698B2 - Interconnector material for solar cell, interconnector for solar cell, and solar cell with interconnector - Google Patents

Description

  The present invention relates to an interconnector material for solar cells, an interconnector for solar cells, and a solar battery cell with an interconnector.

  The solar cell interconnector is a wiring material that mainly plays a role of collecting electrical energy converted by the solar cells by connecting the solar cells made of crystalline Si. In recent years, a solder-coated rectangular copper wire obtained by coating a rectangular copper wire with solder hot dipping has been used as an interconnector material for such a solar cell.

  However, when such a solder-coated flat copper wire is used as an interconnector material for solar cells, there are the following problems. That is, Sn contained in the solder diffuses into Cu constituting the rectangular copper wire due to the thermal history when the solder-covered rectangular copper wire and the solar battery cell are joined by soldering, and Cu—Sn An intermetallic compound is generated, and such an intermetallic compound of Cu—Sn is brittle. Therefore, there is a problem that it causes generation of cracked voids (voids) and cracks, resulting in poor quality.

  On the other hand, for example, Patent Document 1 proposes an interconnector material for a solar cell, in which a flat aluminum substrate is subjected to copper plating and coated with solder hot dipping. On the other hand, in this patent document 1, although a flat aluminum substrate is subjected to copper plating, since copper is expensive, a cheaper interconnector material that does not use copper is required.

JP 2006-49666 A

  The present invention has been made in view of such a situation, and its purpose is substantially free of copper and is relatively inexpensive, and the occurrence of defects such as cracking and peeling of the film due to the thermal history of soldering. An object of the present invention is to provide a solar cell interconnector material and a solar cell interconnector that are effectively prevented. Another object of the present invention is to provide a solar cell with an interconnector obtained by using such an interconnector for solar cells.

The present inventors formed a nickel plating layer having a thickness of 0.2 μm or more and a Sn plating layer in order from the substrate side on the surface of the Al substrate, and then, a solder layer having a thickness of 10 to 30 μm was formed under a predetermined condition. It has been found that the above-mentioned problems can be solved by obtaining an interconnector material for solar cells by forming by hot-dip solder plating, and has completed the present invention.

That is, according to the present invention, a step of forming a Ni plating layer having a thickness of 0.2 μm or more on the surface of the Al substrate in order from the substrate side, and the Ni plating layer and the Sn plating layer on the Al substrate. Forming a solder layer having a thickness of 10 to 30 μm on the surface of the Sn plating layer by a molten solder plating, wherein the molten solder is formed. Plating is performed under conditions of a bath temperature of 140 to 300 ° C. and an immersion time of 3 to 15 seconds, and the Ni plating layer and the Sn plating layer are diffused by heat at the time of performing the molten solder plating, thereby producing an Sn—Ni alloy. Forming a layer, and the Sn—Ni alloy layer is analyzed by high-frequency glow discharge optical emission spectrometry, the Ni strength of the Sn—Ni alloy layer and the Ni plating layer before thermal diffusion The method of manufacturing an interconnector for a solar cell, wherein the ratio of the Ni strength is controlled to 0.15 or more by "Ni strength of Sn-Ni alloy layer / Ni strength of Ni plating layer before thermal diffusion" Is provided.

In the manufacturing method of the present invention, in the step of forming the solder layer, the Sn—Ni alloy layer is preferably formed continuously so as to cover the surface of the Al base .

Furthermore, according to this invention, it has the process of connecting the interconnector for solar cells manufactured by one of the said methods to a photovoltaic cell , The manufacturing method of the photovoltaic cell with an interconnector characterized by the above-mentioned is provided. .
In the method of the interconnector with the solar cell of the present invention, the interconnector for the solar cell and the solar cell, it is preferably connected by soldering.

  According to the present invention, it is not necessary to substantially use copper, so that it is relatively inexpensive, and the occurrence of defects such as cracking and peeling of the film due to the thermal history of soldering is effectively prevented. The interconnector material for solar cells, the interconnector for solar cells, and the solar cell with an interconnector obtained using such an interconnector for solar cells can be provided.

FIG. 1 is a diagram showing a configuration of a solar cell interconnector material 100 according to the present embodiment. FIG. 2 is a diagram showing a configuration of the solar cell interconnector 200 according to the present embodiment. FIG. 3 is a diagram showing a configuration of a solar cell interconnector 200a in which the thickness of the Ni plating layer 20 before thermal diffusion is less than 0.2 μm. 4A is a cross-sectional photograph of the solar cell interconnector sample of Example 2, and FIG. 4B is a cross-sectional photograph of the solar cell interconnector sample of Comparative Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Interconnector materials for solar cells>
FIG. 1 is a diagram showing a configuration of a solar cell interconnector material 100 according to the present embodiment. As shown in FIG. 1, the solar cell interconnector material 100 according to this embodiment is formed by forming a Ni plating layer 20 and a Sn plating layer 30 on both surfaces of an Al base 10 in this order.

  The aluminum plate constituting the Al base 10 is not particularly limited, and a pure aluminum plate or any JIS standard 1000 series, 2000 series, 3000 series, 5000 series, 6000 series, or 7000 series aluminum alloy sheet is used. Among them, a 1000 series O material is particularly preferable. The thickness of the Al base 10 is not particularly limited, and may be a thickness that can secure sufficient conductivity as an interconnector for a solar cell, but is preferably 0.1 to 0.5 mm.

  The Ni plating layer 20 is formed by applying nickel plating on the Al base material 10. The method for forming the Ni plating layer 20 on the Al base 10 is not particularly limited, but it is difficult to directly provide the Ni plating layer on the Al surface, so the Zn layer is formed in advance by displacement plating. After that, a Ni plating layer is preferably formed thereon. Hereinafter, a method for forming a Zn layer as the underlayer will be described.

First, a pure aluminum plate or an aluminum alloy plate constituting the Al base 10 is subjected to a degreasing process, and then subjected to acidic etching and smut removal, followed by Zn substitution plating. The substitution plating of Zn is performed through the steps of nitric acid immersion treatment, first Zn substitution treatment, zinc nitrate stripping treatment, and second Zn substitution treatment. In this case, the water washing process is implemented after the process of each process. Note that the Zn layer formed by the first Zn substitution treatment and the second Zn substitution treatment is slightly dissolved when Ni plating is performed. Therefore, Zn layer coating amount in a state after the Ni plating is preferably in the range of 5 to 500 mg / ^{m 2,} more preferably it is desirable to form to be in the range of 30 to 300 mg / ^{m 2.} The coating amount of the Zn layer can be adjusted by appropriately selecting the concentration of Zn ions in the treatment liquid and the time for immersion in the treatment liquid in the second Zn substitution treatment.

  Next, Ni plating layer 20 is formed by performing Ni plating on the Zn layer as the underlayer. The Ni plating layer 20 may be formed using any plating method of electroplating or electroless plating. The thickness of the Ni plating layer 20 is 0.2 μm or more, preferably 0.2 to 3.0 μm, more preferably 0.5 to 2.0 μm. As will be described later, when the Ni plating layer 20 is formed on the Sn plating layer 30 constituting the interconnector material 100 for a solar cell, the Sn plating layer 30 is formed by heat generated when the solder layer is formed. And a Ni—Sn alloy layer by diffusion.

  The Sn plating layer 30 is formed on the Ni plating layer 20 by performing Sn plating. The Sn plating layer 30 may be formed using any plating method of electroplating or electroless plating. The thickness of the Sn plating layer 30 is preferably 0.5 to 3.0 μm. When the thickness of the Sn plating layer 30 is too thin, solder wettability at the time of forming the solder layer on the Sn plating layer 30 is lowered, and it becomes difficult to form a good solder layer. On the other hand, if the Sn plating layer 30 is too thick, the effect of improving the solder wettability by increasing the thickness is saturated, which is disadvantageous in terms of cost.

<Solar cell interconnector>
FIG. 2 is a diagram showing a configuration of the solar cell interconnector 200 according to the present embodiment. The solar cell interconnector 200 according to the present embodiment uses the solar cell interconnector material 100 shown in FIG. 1 and forms the solder layer 50 on the Sn plating layer 30 of the solar cell interconnector material 100. As shown in FIG. 2, the Sn—Ni alloy layer 40 and the solder layer 50 are formed in this order on both surfaces of the Al base 10.

  The solder layer 50 can be formed by performing molten solder plating on the Sn plating layer 30 constituting the solar cell interconnector material 100 shown in FIG. In the present embodiment, the Ni plating layer constituting the solar cell interconnector material 100 shown in FIG. 1 is formed by forming the solder layer 50 by hot-dip solder plating and by heat when the solder layer 50 is formed. As a result, diffusion occurs between the Sn plating layer 30 and the Sn plating layer 30, thereby forming the Sn—Ni alloy layer 40 under the solder layer 50 as shown in FIG. 2.

  In addition, the bath temperature of molten solder plating in forming the solder layer 50 is preferably 140 to 300 ° C, and more preferably 180 to 250 ° C. Moreover, the immersion time in performing molten solder plating is preferably 3 to 15 seconds. If the bath temperature of the molten solder plating is too low, or if the immersion time when performing the molten solder plating is too short, the formation of the solder layer 50 becomes insufficient, while the bath temperature of the molten solder plating is too high. In the case where the immersion time in performing the molten solder plating is too long, the Sn component contained in the solder layer 50 diffuses to the Al base material 10, and solid solution hardening occurs between Al and Sn. May occur, and the Sn-Ni alloy layer 40 may be cracked or peeled off.

  Although the thickness of the solder layer 50 is not specifically limited, Preferably it is 10-30 micrometers, More preferably, it is 15-30 micrometers.

  As described above, the Sn—Ni alloy layer 40 is diffused between the Ni plating layer 20 and the Sn plating layer 30 constituting the solar cell interconnector material 100 shown in FIG. 1 when the solder layer 50 is formed. Is an alloy layer formed by the occurrence of In the present embodiment, the thickness of the Ni plating layer 20 before thermal diffusion that constitutes the Sn—Ni alloy layer 40 is 0.2 μm or more, preferably 0.2 to 3.0 μm, more preferably 0.5. Since it is set to -2.0 micrometers, the Sn-Ni alloy layer 40 after thermal diffusion can be continuously formed so as to cover the surface of the Al base 10. That is, the Sn—Ni alloy layer 40 after thermal diffusion can be formed in such a manner that there is no break.

  On the other hand, when the thickness of the Ni plating layer 20 before thermal diffusion is less than 0.2 μm, the Sn—Ni alloy after thermal diffusion formed when the solder layer 50 is formed as shown in FIG. An interrupted portion 41 is generated in the layer 40a. And when the discontinuous part 41 generate | occur | produces, from this discontinuous part 41, the adhesiveness of the Al base material 10 and the Sn-Ni alloy layer 40a will fall, the crack of Sn-Ni alloy layer 40a, When a corrosive substance enters through a problem that peeling is likely to occur or a crack generated during processing or the like, a potential difference due to the corrosive substance is generated in the interrupted portion 41, and the corrosion proceeds. This will cause a malfunction.

  On the other hand, according to the present embodiment, the thickness of the Ni plating layer 20 before the thermal diffusion that constitutes the Sn—Ni alloy layer 40 is set to 0.2 μm or more, so that the Sn— The Ni alloy layer 40 can be continuously formed so as to cover the surface of the Al base 10, thereby effectively solving the above problem. If the thickness of the Ni plating layer 20 before thermal diffusion is too thick, the effect of increasing the thickness is saturated, which is disadvantageous in terms of cost.

  Further, in the present embodiment, the Ni intensity of the Sn—Ni alloy layer 40 when analyzed by the high-frequency glow discharge optical emission spectrometry is “Sn—Ni relative to the Ni intensity of the Ni plating layer 20 before thermal diffusion. The ratio of “Ni strength of alloy layer 40 / Ni strength of Ni plating layer 20 before thermal diffusion” is preferably 0.15 or more, more preferably 0.18 or more, and further preferably 0.34 or more. . The upper limit of the ratio is 1 or less.

  By setting the ratio of “Ni strength of Sn—Ni alloy layer 40 / Ni strength of Ni plating layer 20 before thermal diffusion” to the above range, an Sn base material of Sn component contained in Sn—Ni alloy layer 40 Diffusion into 10 can be prevented, thereby causing a problem caused by the Sn component diffusing into the Al base material 10, that is, solid solution hardening occurs between Al and Sn, The trouble that the Sn-Ni alloy layer 40 is cracked or peeled off can be effectively prevented. On the other hand, if the ratio of “Ni strength of Sn—Ni alloy layer 40 / Ni strength of Ni plating layer 20 before thermal diffusion” is too low, that is, the Ni content in Sn—Ni alloy layer 40 is small and Sn content is low. If the ratio is too large, the Sn component in the Sn—Ni alloy layer 40 diffuses into the Al base 10 and solid solution hardening occurs between Al and Sn, and the Sn—Ni alloy layer 40. Cracking or peeling may occur.

  In the present embodiment, “Ni strength of Sn—Ni alloy layer 40 / Ni strength of Ni plating layer 20 before thermal diffusion” is determined by using, for example, a high frequency glow discharge optical emission spectrometer. 40 and the Ni plating layer 20 before thermal diffusion were measured while sputtering with Ar plasma, and in the Sn-Ni alloy layer 40 and the Ni plating layer 20 before thermal diffusion, each of the portions with the highest Ni strength was measured. The data is obtained as the Ni strength of the Sn—Ni alloy layer 40 and the Ni strength of the Ni plating layer 20 before thermal diffusion, respectively, and these are used to calculate “Ni strength of the Sn—Ni alloy layer 40 / before thermal diffusion”. The “Ni strength of the Ni plating layer 20” can be calculated.

  In the present embodiment, the method of setting the ratio of “Ni strength of Sn—Ni alloy layer 40 / Ni strength of Ni plating layer 20 before thermal diffusion” in the above range is not particularly limited. For example, the thickness of the Ni plating layer 20 before thermal diffusion is set to 0.2 μm or more, and the bath temperature of the molten solder plating when forming the solder layer 50 and the immersion time when performing the molten solder plating are within the above-described ranges. And a method of controlling them.

  In addition, as shown in FIG. 3, the solar cell interconnector 200 according to the present embodiment is replaced with a configuration in which the Sn—Ni alloy layer 40 is directly formed on the Al base 10. A configuration in which the Sn—Ni alloy layer 40 is formed on the base material 10 via the Ni plating layer 20 may be employed. In particular, depending on the thickness of the Ni plating layer 20 before thermal diffusion, the bath temperature of the molten solder plating when the solder layer 50 is formed, and the immersion time when performing the molten solder plating, the Ni plating layer 20 is entered. In some cases, the Sn component does not completely diffuse. Therefore, in such a case, the Ni plating layer 20 remains between the Al base 10 and the Sn—Ni alloy layer 40.

  The solar cell interconnector 200 of the present embodiment is formed by diffusion between the Ni plating layer having a thickness of 0.2 μm or more and the Sn plating layer 30 due to heat when the solder layer 50 is formed. Since the Sn—Ni alloy layer 40 is provided, it is possible to effectively prevent the occurrence of defects such as cracking and peeling of the Sn—Ni alloy layer 40 due to the thermal history of soldering. Moreover, the solar cell interconnector 200 of the present embodiment does not substantially contain copper, and is therefore relatively inexpensive and advantageous in terms of cost.

  Therefore, the solar cell with an interconnector obtained by connecting the solar cell interconnector 200 and the solar cell by soldering using the solar cell interconnector 200 of the present embodiment is good in quality. Moreover, it is also excellent in cost.

  In addition, as such a solar cell interconnector 200 of the present embodiment, for example, the Sn—Ni alloy layer 40 and the solder layer 50 are formed on both sides of a long Al plate (coil) according to the method described above. Those formed in this order can be obtained by slitting them to the required width. In the solar cell interconnector 200 thus obtained, the Sn—Ni alloy layer 40 and the solder layer 50 are formed on the upper and lower surfaces, while the surface forming the thickness direction (slit surface) The Sn—Ni alloy layer 40 and the solder layer 50 are not formed.

  Alternatively, the solar cell interconnector 200 of the present embodiment can be obtained, for example, by forming the Sn—Ni alloy layer 40 and the solder layer 50 on the entire surface of the flat Al wire according to the above-described method. it can. In this case, since the obtained solar cell interconnector 200 does not go through the slit process unlike the above-described method, the interconnector described in Patent Document 1 (Japanese Patent Laid-Open No. 2006-49666) described above is used. Similarly, the Sn—Ni alloy layer 40 and the solder layer 50 are formed on both the upper and lower surfaces and the surface forming the thickness direction.

  The size of the solar cell interconnector 200 according to this embodiment is not particularly limited, but the thickness is usually 0.1 to 0.7 mm, preferably 0.1 to 0.5 mm, and the width is Usually, it is 0.5 to 10 mm, preferably 1 to 6 mm, and the length may be appropriately set according to the arrangement of solar cells and the like.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
As a material for forming the Al base 10, an A1100-based O material was prepared (thickness 0.3 mm, width 40 mm, length 120 mm). Then, the Al base material is degreased with an alkaline solution, then etched in sulfuric acid, then desmutted in nitric acid, sodium hydroxide: 150 g / L, Rochelle salt: 50 g / L, oxidized The first Zn substitution treatment was performed by dipping in a treatment solution containing zinc: 25 g / L and ferrous chloride 1.5 g / L. Next, the Al base material subjected to the first Zn substitution treatment is immersed in a 400 g / L nitric acid aqueous solution to remove the deposited Zn, and then in the same treatment liquid as the treatment liquid used in the first Zn substitution treatment. In addition, a Zn layer was formed on the Al substrate with a coating amount of 100 mg / m ² by performing the second Zn substitution treatment by dipping for 10 seconds.

Next, nickel plating was performed on the Al base material 10 on which the Zn layer was formed under the following conditions to form a Ni plating layer 20 having a thickness of 0.2 μm on the Zn layer.
Bath composition: nickel sulfate 250 g / L, nickel chloride 45 g / L, boric acid 30 g / L
pH: 3-5
Bath temperature: 60 ° C
Current density: 1 to 5 A / dm ²

Next, the Al base material 10 on which the Ni plating layer 20 is formed is subjected to tin plating under the following conditions, and a Sn plating layer 30 having a thickness of 0.5 μm is formed on the Ni plating layer. The solar cell interconnector material 100 was obtained.
Bath composition: stannous sulfate 30 g / L, sulfuric acid 70 ml / L, appropriate amount of brightener and antioxidant pH: 1-2
Bath temperature: 40 ° C
Current density: 5-10 A / dm ²

  Next, the solar cell interconnector material 100 thus obtained is immersed in a molten solder plating bath made of Sn—Pb solder whose bath temperature is adjusted to 200 ° C. for 3 seconds to form a solder layer 50 having a thickness of 20 μm. Thus, the solar cell interconnector 200 shown in FIG. 2 was manufactured. In addition, the solar cell interconnector 200 manufactured in this example is the one before slitting, and the size is 40 mm in width and 120 mm in length. By slitting together with the arrangement of solar cells, etc., It can be suitably used as a solar cell interconnector. Then, using the obtained solar cell interconnector material 100 and solar cell interconnector 200, according to the following method, “Ni strength of Sn—Ni alloy layer 40 / Ni of Ni plating layer 20 before thermal diffusion” The ratio of “strength” and the continuity of the Sn—Ni alloy layer 40 were evaluated.

  The ratio of “Ni strength of Sn—Ni alloy layer 40 / Ni strength of Ni plating layer 20 before thermal diffusion” was measured by the following method. That is, first, using a high-frequency glow discharge emission spectroscopic analyzer (GDS-3860, manufactured by Rigaku Corporation), Sn-Ni alloy layer 40 and thermal diffusion under the conditions of high-frequency power: 40 W and photomal voltage (Ni): 370 V. The previous Ni plating layer 20 was measured while sputtering with Ar plasma. Then, from the obtained measurement data, the peak value of each Ni intensity is obtained in the Sn-Ni alloy layer 40 and in the Ni plating layer 20 before thermal diffusion, and the respective Ni values of the Sn-Ni alloy layer 40 are obtained. As the strength and Ni strength of the Ni plating layer 20 before thermal diffusion, “Ni strength of the Sn—Ni alloy layer 40 / Ni strength of the Ni plating layer 20 before thermal diffusion” was calculated. The results are shown in Table 1.

  The continuity of the Sn—Ni alloy layer 40 is determined by observing the cross section of the interconnector 200 for solar cells with a field emission scanning electron microscope (FE-SEM) (JSM-6330F, manufactured by JEOL Ltd.). evaluated. As a result of observation by a field emission scanning electron microscope, a discontinuous portion as shown in FIG. 3, that is, a portion where the solder layer 50 is in direct contact with the surface of the Al base 10 (Al When the Ni content ratio is substantially zero on the surface of the base material 10), it is determined that the Sn—Ni alloy layer 40 has no continuity, and such a discontinuous portion is observed. If not, it was determined that the continuity of the Sn—Ni alloy layer 40 was “present”. The results are shown in Table 1.

<Examples 2 to 4>
Except that the thickness of the Ni plating layer 20 was changed to 0.5 μm (Example 2), 1 μm (Example 3), and 1.5 μm (Example 4), respectively, The battery interconnector material 100 and the solar cell interconnector 200 were obtained and evaluated in the same manner. The results are shown in Table 1.

<Example 5>
The interconnector material for solar cell is the same as that of Example 1, except that the temperature of the molten solder plating tank when forming the solder layer 50 is changed from 200 ° C. to 250 ° C. and the solder layer 50 is formed with a thickness of 20 μm. 100 and solar cell interconnector 200 were obtained and evaluated in the same manner. The results are shown in Table 1.

<Examples 6 to 8>
In the same manner as in Example 5, except that the thickness of the Ni plating layer 20 was changed to 0.5 μm (Example 6), 1 μm (Example 7), and 1.5 μm (Example 8), respectively. The battery interconnector material 100 and the solar cell interconnector 200 were obtained and evaluated in the same manner. The results are shown in Table 1.

<Comparative Examples 1 and 2>
Except for changing the thickness of the Ni plating layer 20 to 0.1 μm (Comparative Example 1) and 0.15 μm (Comparative Example 2), respectively, the solar cell interconnector material 100 and The solar cell interconnector 200 was obtained and evaluated in the same manner. The results are shown in Table 1.

<Comparative Examples 3 and 4>
Except for changing the thickness of the Ni plating layer 20 to 0.1 μm (Comparative Example 3) and 0.15 μm (Comparative Example 4), respectively, the solar cell interconnector material 100 and The solar cell interconnector 200 was obtained and evaluated in the same manner. The results are shown in Table 1.

  As shown in Table 1, in Examples 1 to 8 in which the thickness of the Ni plating layer 20 was 0.2 μm or more, “Ni strength of the Sn—Ni alloy layer 40 / Ni strength of the Ni plating layer 20 before thermal diffusion” In any case, the Sn—Ni alloy layer 40 is continuously formed so as to cover the surface of the Al base 10, and no discontinuity as shown in FIG. 3 is confirmed. It was.

  On the other hand, in Comparative Examples 1 to 4 in which the thickness of the Ni plating layer 20 was less than 0.2 μm, the ratio of “Ni strength of the Sn—Ni alloy layer 40 / Ni strength of the Ni plating layer 20 before thermal diffusion” In both cases, a discontinuous portion was confirmed in the Sn—Ni alloy layer 40, and the Sn—Ni alloy layer 40 did not have continuity.

  Here, FIG. 4A shows a cross-sectional photograph of the solar cell interconnector sample of Example 2, and FIG. 4B shows a cross-sectional photograph of the solar battery interconnector sample of Comparative Example 1. As can be confirmed from FIG. 4A, in Example 2, the Sn—Ni alloy layer 40 is not interrupted, and the Sn—Ni alloy layer 40 is continuous so as to cover the surface of the Al base 10. Can be confirmed. On the other hand, in Comparative Example 1, it can be confirmed that there are discontinuities in the Sn—Ni alloy layer 40 and the Sn—Ni alloy layer 40 has no continuity.

DESCRIPTION OF SYMBOLS 100 ... Solar cell interconnector material 200 ... Solar cell interconnector 10 ... Al base material 20 ... Ni plating layer 30 ... Sn plating layer 40 ... Sn-Ni plating layer 50 ... Solder layer

Claims (4)

A step of forming a Ni plating layer having a thickness of 0.2 μm or more and a Sn plating layer on the Al substrate surface in order from the substrate side;
A step of forming a solder layer having a thickness of 10 to 30 μm on the surface of the Sn plating layer by molten solder plating in a state where the Ni plating layer and the Sn plating layer are formed on the Al base material. A method for manufacturing a battery interconnector, comprising:
The molten solder plating is performed under conditions of a bath temperature of 140 to 300 ° C. and an immersion time of 3 to 15 seconds, and the Ni plating layer and the Sn plating layer are diffused by heat when the molten solder plating is performed. Forming a Ni alloy layer;
For the Sn—Ni alloy layer, the ratio of the Ni strength of the Sn—Ni alloy layer when analyzed by high-frequency glow discharge optical emission spectrometry and the Ni strength of the Ni plating layer before thermal diffusion is expressed as “Sn— The manufacturing method of the interconnector for solar cells, which is controlled to 0.15 or more by “Ni strength of Ni alloy layer / Ni strength of Ni plating layer before thermal diffusion” ”.   2. The solar cell interconnector according to claim 1, wherein in the step of forming the solder layer, the Sn—Ni alloy layer is continuously formed so as to cover the surface of the Al base. Method. Manufacturing method of the interconnector with solar cells, comprising a step of connecting claim 1 or 2 interconnector for a solar cell manufactured by the method according to the solar cell. In the process of connecting the interconnector for the solar cell to the solar cell, the solar cell interconnector and said solar cell, the interconnector with the sun according to claim 3, wherein the connecting by soldering Battery cell manufacturing method .

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