Solder strip for solar cell and solar cell

Abstract

The utility model relates to a welding strip for a solar cell and the solar cell. The solder strip for the solar cell is used for connecting solar cell pieces in series, and at least comprises a core layer; the anti-oxidation metal coating is coated on the surface of the core layer; the thermoplastic conductive layer is coated on the surface of the anti-oxidation metal coating; the thermoplastic conductive layer is suitable for being heated and melted and is cooled and condensed to form a bonding layer after the temperature is removed, and the remaining part of the welding strip is bonded to the solar cell; the formed bonding layer has conductivity; wherein the melting point of the thermoplastic conductive layer is less than 180 DEG C. According to the welding strip for the solar cell, the welding between the welding strip and the solar cell at a low temperature can be realized, and the binding force between the welding strip and the surface of a cell piece is improved, so that the usage amount of silver paste is reduced, and the cost of the solar cell is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, and particularly relates to a solder ribbon for solar cells and a solar cell. Background Art

[0002] With the development of the photovoltaic industry, "cost reduction and efficiency improvement" has been increasingly emphasized by enterprises. At present, through the technology of main-gridless solar cells, solder ribbons are used to replace silver grid electrodes, thereby reducing the usage of silver paste. Currently, there are mainly three technical routes for the solder ribbon technology of main-gridless solar cells, namely the SmartWire solution, the dispensing solution, and the welding and dispensing solution, each with its own advantages and disadvantages. (1) SmartWire solution: First, an organic thin film (copper wire composite film) embedded with a copper solder ribbon is fabricated, and then lamination is carried out to achieve alloying between the solder ribbon and the cell. The biggest difference between this solution and other solutions lies in the need for a copper wire composite film. Although this solution improves the bonding force between the solder ribbon and the cell, it brings problems such as increased cost and optical occlusion. (2) Dispensing solution: First, the entire solder ribbon is fixed on the cell by UV lamp dispensing and curing, and then lamination is carried out to achieve alloying between the solder ribbon and the cell. This solution does not require welding and can be fixed by dispensing. This solution has simple steps and strong equipment stability, but there are shadows under the solder ribbon during electroluminescence (EL) detection and the bonding force between the solder ribbon and the cell is insufficient. (3) Welding and dispensing solution: First, the solder ribbon is welded to the cell for preliminary fixation, then the solder ribbon is further pasted on the cell by dispensing, and then lamination and alloying are carried out. This solution has an additional welding step, which enhances the bonding force, but the solder ribbon is prone to breakage during the shrinkage process of the solder ribbon.

[0003] Existing solder ribbons all need to be connected to solar cell wafers by means of welding and dispensing curing. Since the solder ribbon is getting thinner and thinner, the bonding force between the solder ribbon and the cell will decrease. High-temperature welding will increase the cracking rate of the cell wafers, and fixing with ultraviolet glue will additionally increase the cost of solar cells. Therefore, a solder ribbon is needed that can achieve welding at a lower temperature, thereby reducing the usage of silver paste and the cost of solar cells. Summary of the Utility Model

[0004] Therefore, the utility model provides a solder ribbon for solar cells to solve the problems in the prior art that due to the solder ribbon becoming thinner and thinner, the bonding force between the solder ribbon and the cell decreases, high-temperature welding will increase the cracking rate of the cell wafers, and fixing with ultraviolet glue will additionally increase the cost of solar cells.

[0005] The utility model provides a solder ribbon for solar cells, which is used for serially connecting solar cell wafers and at least includes:

[0006] A core layer;

[0007] An anti-oxidation metal coating, covering the surface of the core layer;

[0008] A thermoplastic conductive layer, covering the surface of the anti-oxidation metal coating;

[0009] The thermoplastic conductive layer is adapted to be melted by heat and cooled and solidified to form an adhesive layer after the temperature is removed, bonding the remaining part of the solder strip to the solar cell; the formed adhesive layer has conductivity;

[0010] Wherein the melting point of the thermoplastic conductive layer is less than 180 °C.

[0011] Optionally, the material of the thermoplastic conductive layer is a resin material doped with conductive particles.

[0012] Optionally, the diameter of the conductive particles is 1 μm - 20 μm.

[0013] Optionally, the conductive particles are silver powder particles, copper powder particles, nickel powder particles, silver-plated resin powder particles, copper-plated resin powder particles or nickel-plated resin powder particles.

[0014] Optionally, the resin material is a thermoplastic polyolefin material with a molecular weight of 10,000 - 200,000.

[0015] Optionally, the resin material is PP, POE, PE, TPO or PU.

[0016] Optionally, the conductivity of the thermoplastic conductive layer is 3×10 5 / Ωcm to 6×10 5 / Ωcm;

[0017] The viscosity of the thermoplastic conductive layer is 3000 mPa·s - 6000 mPa·s;

[0018] The melting temperature / melting point of the thermoplastic conductive layer is 130 °C - 180 °C.

[0019] Optionally, the anti-oxidation metal coating is a silver coating, a tin coating or a nickel coating.

[0020] Optionally, the cross-sectional shape of the solder strip is circular, triangular, trapezoidal, rhombic or semi-circular;

[0021] The diameter of the solder strip is 0.1 mm - 0.3 mm.

[0022] The present utility model further provides a solar cell, comprising the solder strip for the solar cell as described above, including:

[0023] A plurality of parallel-connected solar cell strings;

[0024] The solar cell string comprises a plurality of serially-connected solar cell chips;

[0025] The adjacent solar cells are connected in series through the solder tapes for solar cells.

[0026] The technical solution of the present utility model has the following advantages:

[0027] The solder tape for solar cells provided by the present utility model is provided with a thermoplastic conductive layer on the surface of the solder tape. The thermoplastic conductive layer can be melted by heating at a relatively low temperature (the melting point of the thermoplastic conductive layer is less than 180 °C), and can be cooled and solidified to form an adhesive layer after the temperature is removed, bonding the remaining part of the solder tape to the surface of the solar cell, realizing the welding between the solder tape and the solar cell at a relatively low temperature, improving the bonding force between the solder tape and the surface of the cell, thereby reducing the usage amount of silver paste and the cost of the solar cell. In addition, the formed adhesive layer has conductivity, which can improve the current collection and transmission efficiency of the solder tape. Finally, since the bonding temperature of the solder tape is relatively low and high-temperature treatment is not required, it can be adapted to lower silicon wafer sizes, reducing the cost of silicon wafers. Description of the Drawings

[0028] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 It is a schematic structural diagram of a solder tape for a solar cell according to an embodiment of the present utility model;

[0030] Figure 2 It is a schematic structural diagram of a solar cell according to an embodiment of the present utility model;

[0031] Figure 3 It is a schematic diagram of the connection method of the solder tape in a solar cell according to an embodiment of the present utility model.

[0032] Description of the Reference Numerals:

[0033] 1 - Core layer; 2 - Anti-oxidation metal coating; 3 - Thermoplastic conductive layer; 100 - Solder tape; 200 - Solar cell; 300 - PAD point. Specific Embodiments

[0034] To solve the problems in the prior art that as the welding tape becomes thinner and thinner, the bonding force between the welding tape and the battery decreases, and welding at high temperatures will increase the crack rate of the battery chips, and fixing with ultraviolet glue will additionally increase the cost of the solar cell, the present utility model provides a welding tape for a solar cell, which is used for serially connecting solar cell chips and at least includes: a core layer; an anti-oxidation metal coating covering the surface of the core layer; a thermoplastic conductive layer covering the surface of the anti-oxidation metal coating; the thermoplastic conductive layer is adapted to be melted by heat and cooled and solidified to form an adhesive layer after the temperature is removed, and the remaining part of the welding tape is adhered to the solar cell; the formed adhesive layer has conductivity; wherein the melting point of the thermoplastic conductive layer is less than 180°C.

[0035] The technical solution of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model. In the description of the present utility model, it should be noted that the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0036] Embodiment 1

[0037] Reference Figure 1 , this embodiment provides a welding tape for a solar cell, which is used for serially connecting solar cell chips and at least includes:

[0038] A core layer 1;

[0039] An anti-oxidation metal coating 2 covering the surface of the core layer;

[0040] A thermoplastic conductive layer 3 covering the surface of the anti-oxidation metal coating;

[0041] The thermoplastic conductive layer 3 is adapted to be melted by heat and cooled and solidified to form an adhesive layer after the temperature is removed, and the remaining part of the welding tape is adhered to the solar cell; the formed adhesive layer has conductivity;

[0042] Wherein the melting point of the thermoplastic conductive layer is less than 180°C.

[0043] Specifically, the material of the core layer 1 is copper wire, tin wire, copper-tin alloy wire, etc.

[0044] The solder ribbon for a solar cell provided in this embodiment is provided with a thermoplastic conductive layer on the surface of the solder ribbon. The thermoplastic conductive layer can be melted by heating at a relatively low temperature (the melting point of the thermoplastic conductive layer is less than 180 °C), and can be cooled and solidified to form an adhesive layer after the temperature is removed, bonding the remaining part of the solder ribbon to the surface of the solar cell, realizing the welding between the solder ribbon and the solar cell at a relatively low temperature, improving the bonding force between the solder ribbon and the surface of the cell sheet, thereby reducing the usage amount of silver paste and the cost of the solar cell. In addition, the formed adhesive layer has conductivity, which can improve the current collection and transmission efficiency of the solder ribbon. Finally, since the bonding temperature of the solder ribbon is relatively low and high-temperature treatment is not required, it can be adapted to a lower silicon wafer size, reducing the silicon wafer cost.

[0045] Further, in this embodiment, the material of the thermoplastic conductive layer 3 is a resin material doped with conductive particles.

[0046] By doping conductive particles in the resin material, the solder ribbon can be melted by heating at a relatively low temperature, and can be cooled and solidified to form a conductive viscous layer after the temperature is removed, which can improve the current collection and transmission efficiency of the solder ribbon, enhance the bonding force between the solder ribbon and the surface of the cell sheet, thereby reducing the usage amount of silver paste and the cost of the solar cell.

[0047] Further, in this embodiment, the diameter of the conductive particles is 1 μm - 20 μm, such as 1 μm, 5 μm, 15 μm, 20 μm, etc.

[0048] The diameter of the conductive particles being 1 μm - 20 μm can ensure that the thermoplastic conductive layer 3 has good conductivity. If the diameter of the conductive particles is too large, it may lead to an increase in the particle gap, reducing the number of contact points between the particles, thereby reducing the conductivity of the thermoplastic conductive layer 3, and may also cause the surface of the thermoplastic conductive layer 3 to be uneven; if the diameter of the conductive particles is too small, very small particles are prone to aggregation, resulting in poor dispersibility, thereby affecting the conductivity of the thermoplastic conductive layer 3.

[0049] Further, in this embodiment, the conductive particles are silver powder particles, copper powder particles, nickel powder particles, silver-plated resin powder particles, copper-plated resin powder particles or nickel-plated resin powder particles.

[0050] Further, in this embodiment, the resin material is a thermoplastic polyolefin material with a molecular weight of 10,000 - 200,000.

[0051] Since the thermoplastic polyolefin material with a molecular weight of 10,000 - 200,000 has a relatively low melting temperature, using it as the resin material for the thermoplastic conductive layer enables the thermoplastic conductive layer to be melted by heat at a relatively low temperature and to solidify upon cooling after the temperature is removed, forming an adhesive layer that bonds the remaining part of the solder ribbon to the surface of the solar cell, achieving the soldering between the solder ribbon and the solar cell at a relatively low temperature, enhancing the bonding force between the solder ribbon and the surface of the cell, thereby reducing the usage amount of silver paste and the cost of the solar cell.

[0052] Further, in this embodiment, the resin material is PP, POE, PE, TPO or PU.

[0053] Further, in this embodiment, the conductivity of the thermoplastic conductive layer 3 is 3×10 5 / Ωcm to 6×10 5 / Ωcm, such as 3×10 5 / Ωcm, 4×10 5 / Ωcm, 5×10 5 / Ωcm, 6×10 5 / Ωcm, etc.

[0054] The viscosity of the thermoplastic conductive layer 3 is 3000 mPa·s - 6000 mPa·s, such as 3000 mPa·s, 4000 mPa·s, 5000 mPa·s, 6000 mPa·s, etc.;

[0055] The melting temperature / melting point of the thermoplastic conductive layer 3 is 130°C - 180°C, such as 130°C, 140°C, 155°C, 170°C, 180°C, etc.

[0056] Further, in this embodiment, the anti-oxidation metal coating 2 is a silver coating, a tin coating or a nickel coating.

[0057] The anti-oxidation metal coating 2 can prevent the core layer 1 from reacting with oxygen and moisture in the air, thereby reducing oxidation and corrosion, and further improving the service life and stability of the solder ribbon.

[0058] Further, in this embodiment, the cross-sectional shape of the solder ribbon is circular, triangular, trapezoidal, rhombic or semi-circular;

[0059] The diameter of the solder ribbon is 0.1 mm - 0.3 mm, such as 0.1 mm, 0.15 mm, 0.25 mm, 0.3 mm, etc.

[0060] During specific implementation, the cross-sectional shape of the solder ribbon can be set according to actual requirements, such as circular, triangular, trapezoidal, rhombic or semi-circular, and no limitation is made in this comparative embodiment.

[0061] In this embodiment, the size of the solder ribbon is set according to requirements. The diameter of the solder ribbon is 0.1 mm - 0.3 mm, which is thinner than the conventional solder ribbon, and can reduce the light shielding rate of the solder ribbon on the surface of the solar cell, thereby increasing the light receiving area and efficiency of the solar cell.

[0062] Embodiment 2

[0063] Reference Figure 2 , this embodiment provides a solar cell, including the solder ribbon 100 for the above-mentioned solar cell, and includes:

[0064] Multiple parallel-connected solar cell strings;

[0065] The solar cell string includes several series-connected solar cell chips 200;

[0066] Adjacent solar cell chips 200 are connected in series through the solder ribbon 100 for the solar cell.

[0067] During specific implementation, the thermoplastic conductive layer 3 of the solder ribbon 100 can melt to form an adhesive layer with conductive ability, increasing the adhesive ability with the underlying solar cell chip film layer, and having conductive ability at the same time, which can ensure the connection and conductive functions of the solder ribbon. Due to the existence of the thermoplastic conductive layer 3, it is possible to connect the solder ribbon to the solar cell chip 200 without using methods such as solder joints and PAD points, saving the amount of silver paste used.

[0068] Furthermore, in some embodiments, as Figure 3 shown, the surface of the solar cell chip 200 adopts a PAD point design ( Figure 2 only shows the PAD points of a single solder ribbon, and the PAD points of the other solder ribbons are not shown), and the connection method between the solder ribbon 100 and the solar cell chip 200 in this embodiment is as Figure 3 shown. The PAD point 300 itself is in contact with the TCO of the solar cell chip 200 and serves as a connection medium between the solder ribbon 100 and the TCO. Usually, silver paste is used, which has strong conductive ability but poor adhesive ability with the solder ribbon. After introducing the thermoplastic conductive layer 3, the melted thermoplastic conductive layer 3 contacts the PAD, which can greatly improve the connection strength between the solder ribbon 100 and the PAD point 300. At the same time, the thermoplastic conductive layer 3 itself has certain conductive ability, and can also jointly ensure the conductive ability when the solder ribbon 100 is connected to the solar cell chip 200 with the PAD. Also, due to the common conductive ability of the two, it is possible to reduce the amount of silver paste used for the PAD point 300 on the basis of ensuring the conductive ability between the solder ribbon 100 and the solar cell chip 200..

[0069] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or variations derived therefrom still fall within the protection scope of this utility model creation.

Claims

1. A soldering ribbon for solar cells, used to connect solar cells in series, characterized in that: At least: Core layer; An anti-oxidation metal coating is coated on the surface of the core layer; A thermoplastic conductive layer coated on the surface of the anti-oxidation metal coating; The thermoplastic conductive layer is suitable for melting when heated, and cooling and condensing to form an adhesive layer after the temperature is removed, so as to adhere the remaining part of the soldering ribbon to the solar cell; The formed adhesive layer has electrical conductivity; The melting point of the thermoplastic conductive layer is less than 180°C.

2. The soldering ribbon for solar cells according to claim 1, characterized in that: The material of the thermoplastic conductive layer is a resin material doped with conductive particles.

3. The soldering ribbon for solar cells according to claim 2, characterized in that: The diameter of the conductive particles is 1 μm-20 μm.

4. The soldering ribbon for solar cells according to claim 3, characterized in that: The conductive particles are silver powder particles, copper powder particles, nickel powder particles, silver-plated resin powder particles, copper-plated resin powder particles or nickel-plated resin powder particles.

5. The soldering ribbon for solar cells according to claim 2, characterized in that: The resin material is a thermoplastic polyolefin material with a molecular weight of 10,000-200,000.

6. The soldering ribbon for solar cells according to claim 5, characterized in that The resin material is PP, POE, PE, TPO or PU.

7. The soldering ribbon for solar cells according to claim 1, characterized in that: The conductivity of the thermoplastic conductive layer is 3×10 5 / Ωcm~6×10 5 / Ωcm; The viscosity of the thermoplastic conductive layer is 3000mPa·s-6000mPa·s; The melting temperature / melting point of the thermoplastic conductive layer is 130°C-180°C.

8. The soldering ribbon for solar cells according to claim 1, characterized in that: The anti-oxidation metal coating is a silver coating, a tin coating or a nickel coating.

9. The soldering ribbon for solar cells according to claim 1, characterized in that: The cross-sectional shape of the welding strip is circular, triangular, trapezoidal, rhombus or semicircular; The diameter of the welding strip is 0.1mm-0.3mm.

10. A solar cell, characterized in that: A soldering ribbon for a solar cell according to any one of claims 1 to 9, comprising: Multiple parallel strings of solar cells; The solar cell string comprises a plurality of solar cells connected in series; Adjacent solar cell sheets are connected in series via the soldering ribbons for the solar cells.

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