Conductive adhesive film and its manufacturing method, back contact solar cell

Abstract

The present invention provides a conductive adhesive film and a method for making the same, and a back-contact solar cell. The conductive adhesive film includes an adhesive film layer and a conductive layer located on one side of the adhesive film layer; wherein the conductive layer includes: a base conductive layer located on one side of the adhesive film layer, and the conductive layer is arranged on the adhesive film layer; and a welding layer located on the surface of the base conductive layer away from the adhesive film layer. The base conductive layer and the adhesive film in the present invention are integrated into one, and the reliability is higher. At the same time, the present invention does not require a complex wiring process, and the deposition method is simple, which greatly simplifies the process.

Description

Technical Field

[0001] The present invention relates to the photovoltaic field, and in particular to a conductive adhesive film and a manufacturing method thereof, and a back-contact solar cell. Background Art

[0002] The power generation of photovoltaic modules is proportional to the light-receiving area of ​​the cell. The front of conventional crystalline silicon cells is blocked by the main grid and welding strips, resulting in some areas being unable to receive sunlight. Reducing front shading is an effective way to increase the power generation of photovoltaic modules.

[0003] The positive and negative electrodes of back-contact solar cells (such as IBC cells and MWT cells) are both located on the back of the cell, which greatly reduces the obstruction of sunlight by the front of the back-contact solar cell, thereby improving the conversion efficiency of the solar cell.

[0004] In order to reduce the series resistance of the back-contact photovoltaic module and improve the efficiency of the module, a conductive film can be used to achieve conductive interconnection between the back-contact solar cells. In the prior art, it is more common to use a conductive backplane. For example, CN112635600A discloses a conductive backplane, which includes a substrate and an insulating pattern and a conductive pattern formed on the same side of the substrate; the conductive pattern includes at least two conductors, and the insulating pattern electrically isolates adjacent conductors. The material of the insulating pattern includes insulating glue, insulating ink or insulating wax. The insulating pattern includes a plurality of insulating lines, and the line width of the insulating line is 1mm to 5mm; and / or the conductive pattern is a multi-layer structure. However, the preparation process of the conductive backplane is relatively complicated, often including a multi-layer structure and multiple regions, and the conductive pattern is also prone to problems such as short circuit and leakage, and the reliability is low.

[0005] Based on the above reasons, it is necessary to provide a conductive adhesive film with good reliability and simpler manufacturing process, which is suitable for interconnecting the electrodes of back-contact solar cells. Summary of the invention

[0006] The main purpose of the present invention is to provide a conductive adhesive film and a method for manufacturing the same, and a back-contact solar cell, so as to solve the problems of poor reliability of the conductive backplane and complex wiring process of the composite adhesive film in the prior art.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a conductive adhesive film is provided, which includes an adhesive film layer and a conductive layer located on one side surface of the adhesive film layer; wherein the conductive layer includes: a basic conductive layer, located on one side surface of the adhesive film layer, and the conductive layer is arranged on the adhesive film layer; a welding layer, located on the surface of the basic conductive layer away from the adhesive film layer.

[0008] Further, the material of the base conductive layer is a metal material or a TCO material; preferably, the metal material is copper, aluminum or silver; the TCO material is an ITO material or an AZO material; more preferably, the resistivity of the base conductive layer is less than 10 -3 Ω·cm.

[0009] Furthermore, the material of the welding layer is a low-temperature alloy with a melting point less than 160° C.; preferably, the material of the welding layer is a tin-bismuth-silver alloy.

[0010] Furthermore, the film layer is an EVA film, a POE film or a PVB film; preferably, the vulcanization value ML of the film layer under the test conditions of 120° C. and 2 min is greater than 0.5; preferably, the thickness of the film layer is 10 to 500 μm.

[0011] Furthermore, the base conductive layer has a pattern structure, and the positive electrode current collecting conductive part and the negative electrode current collecting conductive part are respectively arranged on the two side edges of the adhesive film, and the base conductive layer is respectively connected to the positive electrode current collecting conductive part and the negative electrode current collecting conductive part;

[0012] Preferably, the shape of the pattern structure of the base conductive layer corresponds to the positive and negative grid lines in the arrayed cells in the back contact solar cell, wherein the pattern structure is used to interconnect and conduct the positive and negative grid lines in the arrayed cells;

[0013] More preferably, the positive current collecting conductive part and the negative current collecting conductive part are respectively arranged on both side edges of the adhesive film, and the basic conductive layer is located between the positive current collecting conductive part and the negative current collecting conductive part; the basic conductive layer includes a plurality of conductive units arranged in an array corresponding to each battery cell, and each conductive unit includes a plurality of wires arranged in parallel corresponding to the positive and negative electrodes of the battery cell; wherein, the wires corresponding to the positive grid lines of the battery cell among the plurality of wires are recorded as positive wires, and the wires corresponding to the negative grid lines of the battery cell among the wires are recorded as negative wires, and the positive wires and the negative wires in the same conductive unit are arranged alternately; along the direction in which the positive current collecting conductive part extends toward the negative current collecting conductive part, the positive wire of the conductive unit located at the most upstream is connected to the positive current collecting conductive part, and the negative wire of the conductive unit located at the most downstream is connected to the negative current collecting conductive part, and in two adjacent conductive units, the negative wire in the upstream one is connected to the positive wire in the downstream one in a one-to-one correspondence;

[0014] Further preferably, along the direction in which the positive current collecting conductive portion extends toward the negative current collecting conductive portion, among two adjacent conductive units, the negative electrode wire of the upstream one is connected to the positive electrode wire of the downstream one in a one-to-one correspondence and are located in the same straight line, and the positive electrode wire of the upstream one is connected to the negative electrode wire of the downstream one in a one-to-one correspondence and are located in the same straight line; or, along the direction in which the positive current collecting conductive portion extends toward the negative current collecting conductive portion, among two adjacent conductive units, the positive electrode wire of the upstream one is connected to the positive electrode wire of the downstream one in a one-to-one correspondence and are located in the same straight line, and the negative electrode wire of the upstream one is connected to the negative electrode wire of the downstream one in a one-to-one correspondence.

[0015] Furthermore, the width of the wire is 0.01-3 mm; preferably, the thickness of the base conductive layer is 0.1-10 μm; preferably, the thickness of the welding layer is 0.1-20 μm.

[0016] According to another aspect of the present invention, a method for preparing the above-mentioned conductive adhesive film is also provided, which comprises the following steps: preparing an adhesive film layer by extrusion casting; forming a basic conductive layer on one surface of the adhesive film layer; forming a welding layer on the side of the basic conductive layer away from the adhesive film layer, thereby forming a conductive layer including the basic conductive layer and the welding layer to obtain a conductive adhesive film.

[0017] Furthermore, the method for forming the welding layer adopts physical vapor deposition, screen printing, inkjet printing or scraping; the material of the basic conductive layer is a metal material, and the method for forming the basic conductive layer adopts electroplating or conductive slurry screen printing, inkjet printing, coating; or, the material of the basic conductive layer is a TCO material, and the method for forming the basic conductive layer adopts a physical vapor deposition method; preferably, the physical vapor deposition method is magnetron sputtering, thermal evaporation or electron beam evaporation; preferably, at the same time or after forming the basic conductive layer, the positive current collecting conductive part and the negative current collecting conductive part are formed by the same material and method.

[0018] According to another aspect of the present invention, there is also provided a back-contact solar cell, comprising a plurality of cells arranged in an array, characterized in that the above-mentioned conductive adhesive film is provided on one side of the cell where the positive and negative pole grid lines are provided, wherein the conductive layer of the conductive adhesive film is provided in contact with the positive and negative pole grid lines of the cell and is used to make the positive and negative pole grid lines of each cell form a conductive connection.

[0019] Furthermore, each battery cell in the array is provided with a plurality of positive grid lines and a plurality of negative grid lines, and the positive grid lines and the negative grid lines are arranged alternately, and the basic conductive layer in the conductive film has a linear pattern structure adapted to the positive grid lines and the negative grid lines.

[0020] The present invention provides a conductive adhesive film, which includes an adhesive film layer and a conductive layer located on one side surface of the adhesive film layer; wherein the conductive layer includes a base conductive layer and a welding layer, the base conductive layer is located on one side surface of the adhesive film layer, and the conductive layer is arranged on the adhesive film layer; the welding layer is located on the surface of the base conductive layer away from the adhesive film layer. The base conductive layer and the adhesive film in the present invention are integrated into one body, and the reliability is higher. At the same time, the present invention does not require a complicated wiring process, and the deposition method is simple, which greatly simplifies the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0022] Figure 1 A schematic structural diagram of a conductive adhesive film according to an embodiment of the present invention is shown;

[0023] Figure 2 A schematic diagram of a top view of a conductive adhesive film according to an embodiment of the present invention is shown;

[0024] Figure 3 A schematic diagram of a top view of a conductive adhesive film according to another embodiment of the present invention is shown;

[0025] Figure 4 Shows the corresponding Figure 2 A schematic diagram of the structure of two adjacent cells in a cell array in a back contact solar cell with a conductive adhesive film; and

[0026] Figure 5 Shows the corresponding Figure 3 A schematic diagram of the structure of two adjacent cells in an array of cells in a back-contact solar cell with a conductive adhesive film.

[0027] The above drawings include the following reference numerals:

[0028] 10. Adhesive film layer; 20. Conductive layer; 21. Basic conductive layer; 22. Welding layer; 23. Positive electrode current collecting conductive part; 24. Negative electrode current collecting conductive part. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] As described in the background technology section of the present invention, the reliability of the conductive backplane in the prior art is poor and the wiring process of the composite adhesive film is complicated. In order to solve the above problems, the present invention provides a conductive adhesive film, such as Figure 1As shown, the conductive film includes a film layer 10 and a conductive layer 20 located on one side surface of the film layer 10; wherein the conductive layer 20 includes: a basic conductive layer 21, located on one side surface of the film layer 10, and the conductive layer 20 is arranged on the film layer 10; a welding layer 22, located on the surface of the basic conductive layer 21 away from the film layer 10.

[0031] The base conductive layer in the present invention is arranged on the adhesive film layer and integrated with the adhesive film, so the reliability is higher. At the same time, the present invention does not need a complicated wiring process, the deposition method is simple, and the process is greatly simplified.

[0032] In order to further improve the composite effect with the adhesive film, and taking into account the performance of the cell grid lines after conductive interconnection, in a preferred embodiment, the material of the basic conductive layer 21 is a metal material or a TCO material; preferably, the metal material is copper, aluminum or silver, preferably prepared in the form of a conductive paste or electroplating; the TCO material is an ITO material (tin oxide doped indium oxide) or an AZO material (aluminum oxide doped zinc oxide), preferably prepared by physical vapor deposition. The use of the above materials as the basic conductive layer material formed by conductive adhesive film conductive paste printing or physical vapor deposition has more obvious improvements in conductive reliability and integration with the underlying adhesive film layer. In addition, more preferably, the resistivity of the basic conductive layer 21 is less than 10 -3 Ω·cm.

[0033] In a preferred embodiment, the material of the welding layer 30 is a low-temperature alloy with a melting point less than 160°C; preferably, the material of the welding layer 22 is a tin-bismuth-silver alloy. The above materials are selected as welding layer materials to better achieve melt welding during the component lamination process, so that the base conductive layer in the conductive adhesive film and the grid electrode on the battery cell form an atomic bond, thereby better ensuring good electrical contact and high adhesion.

[0034] The adhesive film layer of the present invention can adopt the types commonly used in the field of photovoltaic encapsulation adhesive films, for example: the adhesive film layer 10 includes but is not limited to EVA adhesive film, POE adhesive film or PVB adhesive film. Preferably, the vulcanization value ML of the adhesive film layer 10 under the test conditions of 120°C and 2min is greater than 0.5. In this way, the conductive adhesive film has better effects in packaging properties such as mechanical properties and adhesion properties. In the specific implementation process, the adhesive film layer can meet the above indicators through treatments such as melt finger selection or pre-crosslinking; in addition, high melting point materials, such as materials with a melting point between 90 and 130°C, can also be used to ensure that the above indicators are met. Preferably, the thickness of the adhesive film layer 10 is 10 to 500 μm.

[0035] The conductive adhesive film of the present invention can be used to conduct electricity and interconnect the grid electrodes on each cell in the back contact solar cell. In a preferred embodiment, the base conductive layer 21 has a pattern structure, and the two side edges of the adhesive film layer 10 are respectively provided with a positive current collecting conductive part 23 and a negative current collecting conductive part 24, and the base conductive layer 21 is respectively connected to the positive current collecting conductive part 23 and the negative current collecting conductive part 24. By providing the positive current collecting conductive part 23 and the negative current collecting conductive part 24, the positive grid lines and negative grid lines of the cell after conductive interconnection can be respectively connected to the positive current collecting conductive part 23 and the negative current collecting conductive part 24, thereby playing a current collecting role.

[0036] Preferably, the shape of the pattern structure of the basic conductive layer 21 corresponds to the positive and negative grid lines in the arrayed cells in the back contact solar cell, wherein the pattern structure is used to interconnect the positive and negative grid lines in the arrayed cells. The pattern corresponding to the positive and negative grid lines is more conducive to the conduction of the positive and negative grid lines on the one hand, and can also reduce the shading area of ​​the conductive film on the other hand, ensuring better photoelectric conversion efficiency.

[0037] More preferably, if Figure 2 and 3 As shown, the positive current collecting conductive part 23 and the negative current collecting conductive part 24 are respectively arranged on the two side edges of the adhesive film 10, and the basic conductive layer 21 is located between the positive current collecting conductive part 23 and the negative current collecting conductive part 24; the basic conductive layer 21 includes a plurality of conductive units a arranged in an array corresponding to each battery cell, and each conductive unit a includes a plurality of wires arranged in parallel corresponding to the positive and negative electrodes of the battery cell; wherein, the wires corresponding to the positive grid lines of the battery cell are recorded as positive wires, and the wires corresponding to the negative grid lines of the battery cell are recorded as negative wires, and the positive wires and negative wires in the same conductive unit are arranged alternately; along the direction in which the positive current collecting conductive part 23 extends toward the negative current collecting conductive part 24, the positive wire of the conductive unit located at the most upstream is connected to the positive current collecting conductive part 23, and the negative wire of the conductive unit located at the most downstream is connected to the negative current collecting conductive part 24, and in two adjacent conductive units, the negative wire in the upstream one is connected to the positive wire in the downstream one in a one-to-one correspondence. A battery cell usually has Figure 4 or Figure 5 The structure shown, its surface grid lines serve as positive and negative electrodes, usually with positive and negative electrodes arranged in parallel and alternately. Multiple battery cells are arranged in an array, and the positive and negative grid lines of adjacent battery cells are electrically connected through the basic conductive layer in the above-mentioned conductive film. Correspondingly, the basic conductive layer also has a wire structure corresponding to the positive and negative grid lines, and is arranged in parallel and alternately, and is connected one-to-one through the negative wire in a conductive unit a located upstream and the positive wire in a conductive unit a located downstream, and cooperates with the positive current collecting conductive part 23 and the negative current collecting conductive part 24 connected on both sides, so as to achieve conduction and current collection.

[0038] The materials and preparation process of the positive electrode current collecting conductive part 23 and the negative electrode current collecting conductive part 24 can be the same as those of the basic conductive layer 21. Of course, a conventional bus bar (tinned copper bar) can be placed at the corresponding position when laying the adhesive film 10 to play a busbar and conduction role, and the bus bar is welded and connected with the basic conductive layer 21 and the welding layer 22 during the assembly lamination. Of course, it is preferred to use the same process and materials as the basic conductive layer 21 to prepare the positive electrode current collecting conductive part 23 and the negative electrode current collecting conductive part 24.

[0039] The cells arranged in an array in a back contact solar cell often have two arrangements, namely Figure 4 and Figure 5 For ease of understanding, the solid line in the figure represents the positive grid line, and the dotted line represents the negative grid line. Figure 4 As shown, the positive grid lines and the negative grid lines that need to be connected to each other of the battery cells located in the same row (along the direction extending from the positive current collecting conductive part 23 to the negative current collecting conductive part 24) are located in the same straight line, so that they can correspond to Figure 2 In the conductive film shown, along the direction in which the positive current collecting conductive part 23 extends toward the negative current collecting conductive part 24, in two adjacent conductive units, the negative electrode wire located upstream is connected to the positive electrode wire located downstream in a one-to-one correspondence and are located in the same straight line, and the positive electrode wire located upstream is connected to the negative electrode wire located downstream in a one-to-one correspondence and are located in the same straight line. Or, as Figure 5 As shown, the positive grid lines of the cells in the same row are in the same straight line, and the negative grid lines are in the same straight line. Figure 3 The conductive adhesive film shown in the figure extends along the direction of the positive current collecting conductive part 23 to the negative current collecting conductive part 24. In two adjacent conductive units, the positive electrode wire of the upstream one and the positive electrode wire of the downstream one are located in the same straight line, and the negative electrode wire of the upstream one and the negative electrode wire of the downstream one are located in the same straight line.

[0040] In order to further improve the electrical conduction reliability and further improve the welding stability, in a preferred embodiment, the width of the wire is 0.01-3 mm; preferably, the thickness of the base conductive layer is 0.1-10 μm; preferably, the thickness of the welding layer 22 is 0.1-20 μm.

[0041] According to another aspect of the present invention, a method for preparing the above-mentioned conductive adhesive film is also provided, which includes the following steps: preparing an adhesive film layer 10 by extrusion casting; forming a basic conductive layer 21 on one side surface of the adhesive film layer 10; forming a welding layer 22 on the side surface of the basic conductive layer 21 away from the adhesive film layer 10, thereby forming a conductive layer 20 including the basic conductive layer 21 and the welding layer 22 to obtain a conductive adhesive film.

[0042] The base conductive layer is formed on the adhesive film layer, so that it can be integrated with the adhesive film, and the reliability is higher. At the same time, the present invention does not require a complicated wiring process, and the deposition method is simple, which greatly simplifies the process.

[0043] The above welding layer is preferably made by physical vapor deposition, screen printing, inkjet printing or scraping. In addition, preferably, the material of the base conductive layer 21 is a metal material, and the method of forming the base conductive layer 21 is electroplating or conductive paste screen printing, inkjet printing, coating; or, the material of the base conductive layer 21 is a TCO material, and the method of forming the base conductive layer 21 is a physical vapor deposition method, preferably the physical vapor deposition method is magnetron sputtering, thermal evaporation or electron beam evaporation; preferably, at the same time or after forming the base conductive layer 21, the positive current collecting conductive part 23 and the negative current collecting conductive part 24 are formed by the same material and method.

[0044] According to another aspect of the present invention, there is also provided a back-contact solar cell, comprising a plurality of cells arranged in an array, wherein a conductive adhesive film is arranged on one side of the cell where the positive and negative grid lines are arranged, wherein the conductive layer 20 of the conductive adhesive film is arranged in contact with the positive and negative grid lines of the cell, and is used to make the positive and negative grid lines of each cell conductively connected. By using the conductive adhesive film, the packaging of the back-contact solar cell and the conduction of the grid line electrodes of the cell are simultaneously achieved. Moreover, since the conductive adhesive film has high reliability and simple manufacturing process, while ensuring the reliability of the back-contact solar cell, the production cost is also reduced, and the packaging process is simplified.

[0045] In a preferred embodiment, a plurality of positive grid lines and a plurality of negative grid lines are respectively arranged on each battery cell arranged in the array, and the positive grid lines and the negative grid lines are arranged alternately, and the basic conductive layer 21 in the conductive adhesive film has a linear pattern structure adapted to the positive grid lines and the negative grid lines.

[0046] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0047] Example 1

[0048] This embodiment provides a conductive adhesive film, the structure of which is as follows: Figure 2 As shown, from bottom to top, it includes:

[0049] The adhesive film layer is made of EVA adhesive film with a thickness of 50 μm, a pre-crosslinking degree of 30%, and a vulcanization value ML of 0.6 under the test conditions of 120° C. and 2 min. The adhesive film layer is prepared by a cast extrusion process, and the pre-crosslinking treatment is carried out by electron beam irradiation. The extrusion and electron beam irradiation processes can be carried out by existing processes.

[0050] The conductor layer includes a base conductive layer and a welding layer. The base conductive layer is formed on the film layer by screen printing using commercially available conductive silver paste. Its resistivity is 10 -5 Ω·cm, width is 0.3mm, thickness is 10μm; the welding layer is a tin-bismuth-silver alloy layer, which is formed on the surface of the base conductive layer away from the film layer by magnetron sputtering, has a melting point of 130-140℃, is equal to the base conductive layer in width, and has a thickness of 10μm.

[0051] The same conductive silver paste screen printing process as that of the base conductive layer is adopted, and the positive electrode current collecting conductive part and the negative electrode current collecting conductive part are respectively made on the two side edges of the film layer while printing the base conductive layer.

[0052] Example 2

[0053] The only difference from Example 1 is that a POE film is used, the pre-crosslinking degree is 40%, and the vulcanization value ML is 0.7 under the test conditions of 120° C. and 2 min.

[0054] Example 3

[0055] The only difference from Example 1 is that an EVA film is used, the pre-crosslinking degree is 50%, and the vulcanization value ML is 0.8 under the test conditions of 120° C. and 2 min.

[0056] Example 4

[0057] The only difference from Example 1 is that an EVA film is used, the pre-crosslinking degree is 20%, and the vulcanization value ML is 0.5 under the test conditions of 120° C. and 2 min.

[0058] Example 5

[0059] The only difference from Example 1 is that an EVA film is used without pre-crosslinking, and the vulcanization value ML is 0.3 under the test conditions of 120° C. and 2 min.

[0060] Embodiment 6,

[0061] The only difference from Example 1 is that its structure is as follows Figure 3 As shown, the base conductive layer, the positive electrode current collecting conductive part and the negative electrode current collecting conductive part are formed by electroplating copper, and the resistivity of the base conductive layer is 10 -6 Ω·cm, width is 0.1mm, thickness is 5μm. The electroplating copper plating process is as follows: In the first step, by designing a mask, a layer of seed copper is prepared by magnetron sputtering in the area to be electroplated. The seed copper thickness is 200nm, and then the electroplating process is performed to finally form the desired pattern.

[0062] Example 7

[0063] The only difference from Example 1 is that its structure is as follows Figure 3 As shown, the base conductive layer, the positive current collecting conductive part and the negative current collecting conductive part are deposited with an AZO transparent conductive film by a magnetron sputtering method, and the resistivity of the base conductive layer is 10 -4 Ω·cm, width is 3mm, thickness is 5μm; the magnetron sputtering adopts medium frequency AC magnetron sputtering machine, the target material is AZO target material, and the background vacuum degree is 5×10 -4 Pa, working gas pressure 0.5 Pa, working gas is Ar, and sputtering power is 500 W. During the sputtering process, a mask is used for patterning, that is, the mask is designed to open holes where the conductive layer needs to be deposited.

[0064] Example 8

[0065] The only difference from Example 1 is that the conductor layer includes a base conductive layer and a welding layer. The base conductive layer is formed on the film layer by screen printing using commercially available conductive silver paste, and its resistivity is 10 -6 Ω·cm, width is 0.01mm, thickness is 0.1μm; the welding layer is a tin-bismuth-silver alloy layer, which is formed on the surface of the base conductive layer away from the film layer by magnetron sputtering, has a melting point of 130-140℃, is equal to the base conductive layer in width, and has a thickness of 0.1μm.

[0066] Example 9

[0067] The only difference from Example 1 is that the conductor layer includes a base conductive layer and a welding layer. The base conductive layer is formed on the film layer by screen printing using commercially available conductive silver paste, and its resistivity is 10 -4 Ω·cm, width is 3mm, thickness is 5μm; the welding layer is a tin-bismuth-silver alloy layer, which is formed on the surface of the base conductive layer away from the film layer by magnetron sputtering, has a melting point of 130-140℃, is equal to the base conductive layer in width, and has a thickness of 5μm.

[0068] Comparative Example 1

[0069] The only difference from Example 1 is that the conductor layer includes a base conductive layer, which is formed on the film layer by screen printing using commercially available conductive silver paste, and its resistivity is 10 -3 Ω·cm, width is 3mm, thickness is 20μm; no welding layer.

[0070] Comparative Example 2

[0071] A conductive backplane and conventional EVA packaging film are used to package the battery cells, and the format is consistent with that of the above-mentioned embodiment 1.

[0072] Performance results: The adhesive film of the above embodiment was used to make a small back contact battery module, and the EL and power were evaluated. At the same time, the appearance was observed. The results are shown in the following table:

[0073] Table 1

[0074] EL Image Power / W Appearance Example 1 No local dimming 32.5 good Example 2 No local dimming 32.8 good Example 3 No local dimming 32.6 good Example 4 Only one dark spot 31.7 good Example 5 Local darkening 30.6 Conductive pattern offset Example 6 No local dimming 33.1 good Example 7 No local dimming 32.0 good Example 8 No local dimming 31.9 good Example 9 No local dimming 31.7 good Comparative Example 1 Overall dark 24.3 There is local delamination Comparative Example 2 Local darkening 28.2 good

[0075] According to the above results, using a film with suitable fluidity as the base film can achieve good conductive effect and appearance. Due to different conductive materials, the power of small components is different. The electroplated copper solution has the highest power, the conductive silver paste is slightly lower, and the TCO is relatively poor, but the basic difference is less than 3%. For the film with general fluidity, there is an obvious pattern shift in the appearance of the small component, and there is a local darkening in the EL image, indicating that the conductivity is reduced, and its power is significantly reduced by about 30%. Comparative Example 1 has a film without a welding layer, which only has mechanical contact with the battery cell, poor conductivity, and the overall EL is dark, and the power is reduced. Comparative Example 2 uses a conductive backplane for packaging, and the power is significantly lower than the embodiment, and especially the conductive backplane process is complex and the cost is high.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A conductive adhesive film, characterized in that: The conductive adhesive film comprises an adhesive film layer (10) and a conductive layer (20) located on one side surface of the adhesive film layer (10); wherein the conductive layer (20) comprises: A base conductive layer (21) is located on a surface of one side of the adhesive film layer (10), and the conductive layer (20) is arranged on the adhesive film layer (10); A welding layer (22) located on a surface of the base conductive layer (21) that is away from the adhesive film layer (10); The basic conductive layer (21) has a pattern structure, and the two side edges of the adhesive film layer (10) are respectively provided with a positive electrode current collecting conductive part (23) and a negative electrode current collecting conductive part (24), and the basic conductive layer (21) is respectively connected to the positive electrode current collecting conductive part (23) and the negative electrode current collecting conductive part (24).

2. The conductive adhesive film according to claim 1, characterized in that: The material of the basic conductive layer (21) is a metal material or a TCO material.

3. The conductive adhesive film according to claim 2, characterized in that: The metal material is copper, aluminum or silver; the TCO material is ITO material or AZO material.

4. The conductive adhesive film according to claim 2, characterized in that: The resistivity of the base conductive layer (21) is less than 10 -3 Ω·cm.

5. The conductive adhesive film according to any one of claims 1 to 4, characterized in that: The material of the welding layer (22) is a low-temperature alloy having a melting point less than 160°C.

6. The conductive adhesive film according to claim 5, characterized in that: The material of the welding layer (22) is a tin-bismuth-silver alloy.

7. The conductive adhesive film according to any one of claims 1 to 4, characterized in that: The adhesive film layer (10) is an EVA adhesive film, a POE adhesive film or a PVB adhesive film.

8. The conductive adhesive film according to claim 7, characterized in that: The film layer (10) has a vulcanization value ML greater than 0.5 under the test conditions of 120° C. and 2 min.

9. The conductive adhesive film according to claim 7, characterized in that: The thickness of the adhesive film layer (10) is 10-500 μm.

10. The conductive adhesive film according to any one of claims 1 to 4, characterized in that: The shape of the pattern structure of the basic conductive layer (21) corresponds to the positive and negative pole grid lines in the array-arranged battery cells in the back contact solar cell, wherein the pattern structure is used to interconnect and conduct the positive and negative pole grid lines in the array-arranged battery cells.

11. The conductive adhesive film according to claim 10, characterized in that: The positive electrode current collecting conductive part (23) and the negative electrode current collecting conductive part (24) are respectively arranged on both side edges of the adhesive film layer (10), and the basic conductive layer (21) is located between the positive electrode current collecting conductive part (23) and the negative electrode current collecting conductive part (24); the basic conductive layer (21) comprises a plurality of conductive units arranged in an array corresponding to each of the battery cells, and each of the conductive units comprises a plurality of conductive wires arranged in parallel corresponding to the positive and negative electrodes of the battery cell; wherein the conductive wires corresponding to the positive electrode grid lines of the battery cell are recorded as positive electrode wires, and the conductive wires corresponding to the positive electrode grid lines of the battery cell are recorded as positive electrode wires. The negative electrode grid line of the cell sheet is recorded as a negative electrode wire, and the positive electrode wire and the negative electrode wire in the same conductive unit are arranged alternately; along the direction in which the positive current collecting conductive part (23) extends toward the negative current collecting conductive part (24), the positive electrode wire of the conductive unit located at the most upstream is connected to the positive current collecting conductive part (23), and the negative electrode wire of the conductive unit located at the most downstream is connected to the negative current collecting conductive part (24), and in two adjacent conductive units, the negative electrode wire in the upstream one is connected to the positive electrode wire in the downstream one in a one-to-one correspondence.

12. The conductive adhesive film according to claim 11, characterized in that: Along the direction in which the positive current collecting conductive portion (23) extends toward the negative current collecting conductive portion (24), in two adjacent conductive units, the negative electrode wire of the upstream one is connected to the positive electrode wire of the downstream one in a one-to-one correspondence and are located on the same straight line, and the positive electrode wire of the upstream one is connected to the negative electrode wire of the downstream one in a one-to-one correspondence and are located on the same straight line; or, along the direction in which the positive current collecting conductive portion (23) extends toward the negative current collecting conductive portion (24), in two adjacent conductive units, the positive electrode wire of the upstream one is connected to the positive electrode wire of the downstream one in a one-to-one correspondence and are located on the same straight line, and the negative electrode wire of the upstream one is connected to the negative electrode wire of the downstream one in a one-to-one correspondence.

13. The conductive adhesive film according to claim 11, characterized in that: The width of the wire is 0.01-3 mm.

14. The conductive adhesive film according to claim 11, characterized in that: The thickness of the base conductive layer is 0.1-10 μm.

15. The conductive adhesive film according to claim 11, characterized in that: The welding layer (22) has a thickness of 0.1-20 μm.

16. A method for producing a conductive adhesive film according to any one of claims 1 to 15, characterized in that: The following steps are involved: The film layer (10) is prepared by extrusion casting; Forming a base conductive layer (21) on one side surface of the adhesive film layer (10); A welding layer (22) is formed on a surface of the base conductive layer (21) that is away from the adhesive film layer (10), thereby forming a conductive layer (20) including the base conductive layer (21) and the welding layer (22), thereby obtaining the conductive adhesive film.

17. The manufacturing method according to claim 16, characterized in that: The method for forming the welding layer (22) adopts physical vapor deposition, screen printing, inkjet printing or scraping; the material of the basic conductive layer (21) is a metal material, and the method for forming the basic conductive layer (21) adopts electroplating or conductive paste screen printing, inkjet printing, coating; or, the material of the basic conductive layer (21) is a TCO material, and the method for forming the basic conductive layer (21) adopts a physical vapor deposition method.

18. The manufacturing method according to claim 17, characterized in that: The physical vapor deposition method is magnetron sputtering, thermal evaporation or electron beam evaporation.

19. The manufacturing method according to claim 17, characterized in that: At the same time or after the base conductive layer (21) is formed, a positive electrode current collecting conductive portion (23) and a negative electrode current collecting conductive portion (24) are formed using the same material and method.

20. A back-contact solar cell, comprising a plurality of cells arranged in an array, characterized in that: A conductive adhesive film according to any one of claims 1 to 15 is provided on one side of the battery cell where the positive and negative electrode grid lines are provided, wherein the conductive layer (20) of the conductive adhesive film is provided in contact with the positive and negative electrode grid lines of the battery cell and is used to enable the positive and negative electrode grid lines of each battery cell to form conductive connections.

21. The back contact solar cell according to claim 20, characterized in that: A plurality of positive grid lines and a plurality of negative grid lines are respectively arranged on each of the battery cells arranged in the array, and each of the positive grid lines and each of the negative grid lines are arranged alternately, and the base conductive layer (21) in the conductive adhesive film has a linear pattern structure adapted to the positive grid lines and the negative grid lines.

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