CN113725304A - Heterojunction battery welding method - Google Patents

Heterojunction battery welding method Download PDF

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Publication number
CN113725304A
CN113725304A CN202110923815.7A CN202110923815A CN113725304A CN 113725304 A CN113725304 A CN 113725304A CN 202110923815 A CN202110923815 A CN 202110923815A CN 113725304 A CN113725304 A CN 113725304A
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welding
welded
battery
point
slurry
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林长江
龚道仁
郭琦
李晨
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Xuancheng Ruihui Xuansheng Enterprise Management Center Partnership LP
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Xuancheng Ruihui Xuansheng Enterprise Management Center Partnership LP
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

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  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
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  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Connection Of Batteries Or Terminals (AREA)

Abstract

The application provides a heterojunction battery welding method, and belongs to the technical field of solar battery preparation. The heterojunction battery welding method comprises the following steps: forming an adhesion layer on the surface of a to-be-welded point on at least one side surface of a to-be-welded battery piece to obtain a slurry-combined battery piece, wherein the material in the adhesion layer is at least partially the same as the material of the surface of the to-be-welded point and the material of a welding strip for connecting the to-be-welded battery piece; in a set low-temperature welding temperature range, the adhesion layer and the welding strip are partially melted, so that the adjacent slurry-combined battery pieces are connected through welding of the welding strip; the material of the surface of the to-be-welded point at least comprises silver and tin alloy, and the slurry for forming the adhesion layer comprises tin alloy powder, soldering flux and other auxiliaries. According to the heterojunction battery welding method, the stability of the welding process is guaranteed under the condition that the low temperature is kept, the string yield between the heterojunction battery pieces is improved, and the efficiency of the heterojunction battery assembly is improved.

Description

Heterojunction battery welding method
Technical Field
The application relates to the technical field of solar cell preparation, in particular to a heterojunction cell welding method.
Background
In recent years, the solar cell industry is rapidly developed, and the power generation efficiency of the solar cell is increasingly improved. After the solar cell is prepared, the solar cells need to be welded together by using a welding technology to form a cell string, and then the cell string is formed into a solar cell module.
The heterojunction cell has the advantages of high conversion efficiency, low attenuation, low temperature coefficient, high double-sided rate and the like, and is a typical representative of the solar cell with great application prospect. The preparation process temperature of each film layer of the heterojunction battery is below 250 ℃, in order to keep the electrical property of the heterojunction battery piece, the film layers are not damaged, and the preparation temperature of the subsequent assemblies is not more than 230 ℃ within a certain time. The low-temperature welding problem of the existing heterojunction battery is a main problem for restricting the release of the production energy of a heterojunction battery assembly. The method is mainly characterized in that the temperature window of the welding process of the heterojunction battery is narrow, the phenomena of insufficient solder and over-soldering are easily generated, the stability of the welding process cannot be ensured, and the welding yield of the battery piece is low.
Disclosure of Invention
In view of the above, the present application provides a method for welding a heterojunction battery, which at least partially solves the above problems in the prior art.
The heterojunction battery welding method comprises the following steps:
forming an adhesion layer on the surface of a to-be-welded point on at least one side surface of a to-be-welded battery piece to obtain a slurry-combined battery piece, wherein the material in the adhesion layer is at least partially the same as the material of the surface of the to-be-welded point and the material of a welding strip for connecting the to-be-welded battery piece;
in a set low-temperature welding temperature range, the adhesion layer and the welding strip are partially melted, so that the adjacent slurry-combined battery pieces are connected through welding of the welding strip;
the material of the surface of the to-be-welded point at least comprises silver and tin alloy, and the slurry for forming the adhesion layer comprises tin alloy powder, soldering flux and other auxiliaries.
According to a specific implementation form of the embodiment of the application, the forming of the adhesion layer on the surface of the to-be-welded point on the surface of at least one side of the to-be-welded battery piece comprises:
conveying the battery plate to be welded to a slurry printing platform, and positioning the surface of the welding point to be welded;
calling the slurry to the upper part of the printing screen;
and enabling the slurry to permeate the printing screen plate, and printing on the surface of a to-be-welded point of the battery piece to form an adhesion layer to obtain the slurry-combined battery piece.
According to a specific implementation form of the embodiment of the application, the surface of the to-be-soldered point at least includes a PAD point on the front side and a PAD point on the back side, and the surface of the to-be-soldered point is positioned as follows: and respectively positioning the PAD point on the front side and the PAD point on the back side of the battery piece to be welded by adopting an image sensor.
According to a specific implementation form of the embodiment of the application, the surface of the to-be-welded point further comprises a front main grid line and a back main grid line, and the surface of the to-be-welded point is positioned as follows: and positioning the PAD point on the front surface and/or the main grid line on the front surface of the battery piece to be welded, and the PAD point on the back surface and/or the main grid line on the back surface by adopting the image sensor.
According to a particular implementation form of the embodiment of the application, the thickness of the printing screen is 5 μm to 50 μm, and the thickness of the adhesion layer is 5 μm to 50 μm.
According to a concrete implementation form of this application embodiment, the solder strip includes copper wire and the tin alloy layer that is located the copper wire periphery, will close thick liquid battery piece and weld including:
coating the soldering strip with soldering flux in a soaking mode or a smearing mode;
heating the paste-mixed battery piece to reach a set low-temperature welding temperature range, so that the silver and tin alloy on the surface of the point to be welded in the paste-mixed battery piece is at least partially melted;
aligning the surface of the point to be welded in the adjacent slurry-mixed cell piece with the solder strip, and melting and combining the tin alloy layer on the surface of the solder strip with the tin alloy in the silver and tin alloy in the slurry-mixed cell piece, so that the solder strip and the slurry-mixed cell piece are welded together.
According to a specific implementation form of the embodiment of the application, the soaking mode includes: the welding strip passes through a soldering flux liquid tank container and is submerged in soldering flux liquid, and the welding strip is drawn by a welding strip drawing mechanism to pass through the soldering flux liquid tank container, so that the soldering flux is attached to the surface of the welding strip;
the smearing mode comprises the following steps: the welding strip passes through the sponge soaked with the soldering flux liquid, is soaked in the soldering flux liquid, and is dragged to pass through the sponge in the soldering flux liquid along with the welding strip stretching mechanism, so that the soldering flux is attached to the surface of the welding strip.
According to a specific implementation form of the embodiment of the application, in a set low-temperature welding temperature range, the heating mode during welding is that the surface of the point to be welded is heated by combining infrared lamp tube irradiation heat conduction and pressing pin heat conduction, and the set low-temperature welding temperature range is 170-230 ℃.
According to a specific implementation form of the embodiment of the application, the slurry further comprises copper powder particles or silver powder particles, and the adding amount of the copper powder particles or the silver powder particles is 0.5% -5% of the weight of the slurry;
the solder strip comprises tin-lead-bismuth Sn-Pb-Bi, the specific gravity range of the tin Sn in the alloy is 40% -46%, the specific gravity range of the lead Pb in the alloy is 40% -46%, and the specific gravity range of the bismuth Bi in the alloy is 11% -17%;
or the solder strip comprises Sn-Bi, the specific gravity range of the Sn in the alloy is 40-46%, and the specific gravity range of the Bi in the alloy is 54-60%.
According to a specific implementation form of the embodiment of the application, after the adhesion layer is formed on the surface of the to-be-welded point on one side surface of the to-be-welded battery piece, the to-be-welded battery piece is turned over through the turning mechanism and repositioned so as to form the adhesion layer on the surface of the to-be-welded point on the other side surface.
Advantageous effects
According to the heterojunction battery welding method that the application provided, through the process that increases one section thick liquids printing before solar wafer welds, including treating the at least one side surface of welding wafer and treating the welding point surface formation adhesion layer, and in the welding strip welding process, make adhesion layer and welding strip part melting, in order to close adjacent thick liquids battery piece and pass through welding strip welded connection, the thick liquids of printing play the effect of connecting the bridge, thereby make the welding strip better with the welding effect of heterojunction battery piece under keeping microthermal condition, improve welding tension between the two, promote the cluster yield between the battery piece, improve battery pack's efficiency, and promote stability of welding machine and equipment productivity.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flow chart of a heterojunction battery welding method according to an embodiment of the invention;
fig. 2 is a flow chart of heterojunction battery paste printing according to an embodiment of the invention;
fig. 3 is a flow chart of heterojunction cell welding according to an embodiment of the invention.
Detailed Description
The embodiments of the present application will be described in detail below with reference to the accompanying drawings.
The following description of the embodiments of the present application is provided by way of specific examples, and other advantages and effects of the present application will be readily apparent to those skilled in the art from the disclosure herein. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. The present application is capable of other and different embodiments and its several details are capable of modifications and/or changes in various respects, all without departing from the spirit of the present application. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It is noted that various aspects of the embodiments are described below within the scope of the appended claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present application, one skilled in the art should appreciate that one aspect described herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. Additionally, such an apparatus may be implemented and/or such a method may be practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present application, and the drawings only show the components related to the present application rather than the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.
The existing welding mode commonly used for the heterojunction battery is a method combining infrared heat conduction welding and pressing pin contact welding strip welding to realize welding, and the infrared heat conduction is large-area high-temperature heating on the surface of the battery, so that the internal structure of the heterojunction battery sheet is easily damaged, the electrical property is reduced and the like; the temperature window of the heterojunction battery welding process is narrow, the productivity of equipment is sacrificed by adjusting the temperature of the infrared lamp tube, adjusting the press pin, prolonging the welding time and the like, the phenomena of insufficient solder and over-soldering can be relieved to a certain extent, the stability of the welding process can not be ensured, and the welding series welding yield of the battery piece is still low.
To solve this problem, the inventor proposes a technical idea that: increase the technology of thick liquids printing at welding machine material loading machine anterior segment, can form the adhesive layer to the point of welding surface of waiting of heterojunction battery piece before the welding, in welding process, silver in the thick liquids on the heterojunction battery piece, tin alloy in the tin alloy fuses earlier with the silver thick liquids on the grid line and welds with the tin alloy layer on the solder strip, the thick liquids on the battery piece is regarded as the bridge of being connected of battery piece and solder strip, improve the butt fusion effect of solder strip and battery piece, improve the welding pulling force, and then promote heterojunction battery cluster welding effect, promote the cluster yield of heterojunction battery piece welding bunching.
Accordingly, in response to the above problems, the present application provides a heterojunction battery welding method, which is described in detail below with reference to fig. 1-3.
The cell pieces need to be provided before the welding of the heterojunction cell, and the specific cell piece preparation method can be adjusted according to the type of the cell piece which is actually applied, and is not limited to the heterojunction cell provided in the application.
In one embodiment, the cell may be an N-type cell, specifically, the N-type cell is a heterojunction cell, and can be prepared by a conventional known preparation method, for example, an N-type monocrystalline silicon wafer is first cleaned and textured to form a pyramid textured surface, impurity ions are removed, and the surface is cleaned; respectively plating intrinsic amorphous silicon layers on two sides of an N-type monocrystalline silicon wafer by using Chemical Vapor Deposition (CVD) equipment, plating an N-type amorphous silicon layer outside the intrinsic amorphous silicon layer on one side to form a high-low junction structure, and plating a P-type amorphous silicon layer outside the intrinsic amorphous silicon layer on the other side to form a PN junction structure; then, respectively preparing a transparent conductive film layer on the outer sides of the N-type amorphous silicon layer and the P-type amorphous silicon layer by a Physical Vapor Deposition (PVD) or Reactive Plasma Deposition (RPD) method; and after the coating of the transparent conductive film layer is finished, printing the silver grid line electrode on the transparent conductive film layer in a screen printing mode.
In this embodiment, the heterojunction battery welding method includes the steps of:
s101, forming an adhesion layer on the surface of a to-be-welded point on at least one side surface of a to-be-welded battery piece to obtain a paste-combined battery piece, wherein at least part of materials in the adhesion layer are the same as those of the to-be-welded point surface and a welding strip for connecting the to-be-welded battery piece, the materials of the to-be-welded point surface at least comprise silver and tin alloy, and the paste in the adhesion layer comprises tin alloy powder, soldering flux and other auxiliaries.
In this embodiment, an adhesion layer is formed on the surface of the to-be-welded point on the surface of one side of the heterojunction battery piece prepared in the above embodiment, the heterojunction battery piece may be cut by a slicer and then transferred to a paste printing device by a transfer device, so as to perform paste printing on the surface of one side of the heterojunction battery piece, where the paste printing may be paste printing on the surface of the to-be-welded point on the front side or paste printing on the surface of the to-be-welded point on the back side.
Further, the paste printing apparatus used in step S101 mainly includes a control mechanism, a paste storage mechanism, a paste printing platform, a positioning mechanism, a printing screen, and a printing roller. The specific steps of forming an adhesive layer on the surface of the point to be welded of the heterojunction cell to obtain the paste-combined cell refer to fig. 2, which includes:
s1011, conveying the battery piece to a slurry printing platform and positioning. The paste printing platform is used for bearing a battery piece, the battery piece is accurately positioned through a positioning mechanism, specifically, the surface of a point to be welded at least comprises a front PAD point and a back PAD point, the front PAD point and the back PAD point of the battery piece are respectively positioned through an image sensor, or the front PAD point and the back PAD point are also positioned through a front main grid line and a back main grid line, the image sensor can be positioned through a CCD (Charge Coupled Device), but not limited to the CCD positioning mode, and the positioning mode can be changed according to practical application scenes, wherein the PAD points are a plurality of local points on the main grid line, and the local points are uniformly distributed on the main grid line as wiring points and are positioned at the intersection of the thin grid line and the main grid line. The PAD point has various size specifications and shape specifications and is used for contact fixation of the welding strip and the battery piece.
And S1012, transferring the paste to the upper part of the printing screen plate. And when the battery piece is detected to be positioned, the control mechanism calls the slurry in the slurry storage mechanism to be above the printing screen. It should be understood here that the slurry used is a low temperature slurry, ranging from 170 ℃ to 230 ℃, matching the heterojunction cell characteristics in practical use.
And S1013, enabling the slurry to permeate the printing screen plate, and uniformly printing on the surface of the to-be-welded point of the battery piece to form an adhesion layer to obtain the slurry-combined battery piece. And extruding the viscous slurry above the printing screen at a certain speed and pressure by a printing roller shaft, and penetrating the slurry to the surface of the heterojunction battery through gaps of the printing screen.
More specifically, the paste printing may be PAD dot printing only, main gate line printing only, or both main gate line and PAD dot printing. Therefore, the pattern of the printing screen can be adjusted according to the actual slurry printing mode to be a pattern which accords with different printing modes.
In one embodiment, the thickness of the printing screen is 5-50 μm, and the thickness of the printing screen can be adjusted according to actual requirements. In general, the thickness of the adhesion layer is equivalent to the thickness of the printing screen plate, in this embodiment, the thickness of the adhesion layer is 5 μm to 50 μm, and the solder piling is easily caused by too much paste printing, which affects the soldering effect.
And S102, in a set low-temperature welding temperature range, partially melting the adhesion layer and the welding strip to connect adjacent slurry-combined battery pieces through welding of the welding strip.
The welding is mainly carried out in a welding machine, and the welding strip is connected with the battery pieces in a heating mode by utilizing the welding strip, so that the single slurry-combined battery pieces are welded together in series to form the battery string. As shown in fig. 3, the method specifically includes the following more detailed steps:
and S1021, coating the soldering strip with the soldering flux in a soaking mode or a smearing mode.
The solder strip comprises a copper wire and a tin alloy layer positioned on the periphery of the copper wire. In the welding process, firstly, the welding strip is laid according to a path, the scaling powder of the welding strip is coated, the number of the welding strip can be determined according to the number of grid lines of the battery piece, including 6 grids, 9 grids, 12 grids and the like, and the shape of the welding strip can be a round welding strip of tin-plated alloy or a special-shaped welding strip and the like. According to the soldering sequence, the front solder strip or the back solder strip can be applied with the flux first, which is not limited herein. Specifically, the coating mode of the soldering flux is a soaking mode or a smearing mode, and the soaking mode specifically comprises the following steps: the welding strip is submerged through the scaling powder liquid tank container and is dragged along with the welding strip stretching mechanism, and the scaling powder is attached to the surface. The smearing mode specifically comprises the following steps: the welding strip is soaked by sponge soaked with the soldering flux and is dragged along with the welding strip stretching mechanism, and the soldering flux is attached to the surface of the welding strip.
And S1022, heating the paste-combined battery piece to reach the set low-temperature welding temperature range, so that the silver and tin alloy on the surface of the point to be welded in the paste-combined battery piece is at least partially melted.
The welding process adopts low-temperature welding, and the welding temperature is controlled to be 170-230 ℃ so as to avoid burning the film structure of the heterojunction battery and influencing the battery performance. During specific low-temperature control, the temperature parameters of the infrared lamp tube and the temperature parameters of the bottom plate are adjusted through the welding machine, so that the surface of the to-be-welded point can reach a set temperature range under the condition that the infrared lamp tube irradiation heat conduction and the press pin heat conduction are combined.
And S1023, aligning the surfaces of points to be welded in the adjacent paste-mixed battery pieces with the solder strips, and fusing and combining the tin alloy layers on the surfaces of the solder strips with the silver and tin alloys in the paste-mixed battery pieces to weld the solder strips and the paste-mixed battery pieces together.
In the process, the heating mode is the combination of infrared lamp tube irradiation heat conduction and pressing pin heat conduction, so that the surface of the welding point reaches the set temperature, and after heating, the tin alloy layer coated on the surface of the welding strip and the slurry printed on the battery piece can be better fused and combined. Because the thick liquids on the battery piece of the combination thick liquid are printed on main grid line or PAD point, make the tin on the surface of solder strip fuse with the thick liquids on the battery piece of the combination thick liquid through heating, and then make the silver thick liquid of main grid line or PAD point and the better fusion connection of the thick liquids of solder strip, also the thick liquids on the battery piece of the combination thick liquid play a bridge of connecting to improve the low temperature silver thick liquid and the solder strip welding process window that the heterojunction battery formed main grid line or PAD point, effectively improve solder strip and heterojunction battery piece welding pull.
The solder strip in this embodiment includes Sn-Pb-Bi, and is suitable for low temperature soldering. The alloy comprises the following components in percentage by weight: the specific gravity of the tin Sn in the alloy ranges from 40% to 46%, and 43% is preferable; the specific gravity of lead Pb in the alloy ranges from 40% to 46%, and the lead Pb in the alloy is preferably 43%; the specific gravity of bismuth Bi in the alloy is in the range of 11% to 17%, preferably 14%. Furthermore, copper powder particles or silver powder particles can be added into the alloy in the slurry, so that the comprehensive performance between the welding strip and the battery piece is improved. Specifically, the adding amount of the copper powder particles or the silver powder particles is 0.5 to 5 percent of the weight of the slurry.
The solder strip includes only Sn-Pb-Bi alloy, and does not include soldering flux. The welding temperature of the low-temperature welding strip is below 200 ℃, the welding temperature of the heterojunction battery is below 230 ℃, the low-temperature performance of the heterojunction battery can be completely met by adopting the welding strip, and the welding strip has good wettability and welding performance.
From an environmental standpoint, the solder strip is preferably a lead-free solder strip that includes tin bismuth Sn-B i. The alloy comprises the following components in percentage by weight: the specific gravity of the tin Sn in the alloy ranges from 40% to 46%, and 43% is preferable; the specific gravity of bismuth Bi in the alloy is in the range of 54% to 60%, preferably 57%. The solder strip "in alloy" is analogous to the solder strip of Sn-Pb-Bi, without the flux.
Further, before step S1021, the method further includes: conveying a combined paste battery piece into a welding machine, wherein each combined paste battery piece comprises n combined paste battery pieces, n is more than or equal to 2, and n is a positive integer; and after the battery piece is conveyed to the welding position, the slurry combining battery piece is heated until the tin alloy layer on the surface of the welding strip is fused and combined with the tin alloy in the silver and tin alloy of the main grid line or the PAD point on the slurry combining battery piece, so that the welding strip and the slurry combining battery piece are welded into a whole, and the heterojunction battery string is obtained. And after the welding is finished, outputting the welded heterojunction battery string, and simultaneously heating and welding the next combined paste battery piece and the welding strip.
In a preferred embodiment, the adhesion layers are formed on the surfaces of the points to be welded on the two sides of the heterojunction cell sheet, namely the formation of the adhesion layers comprises front paste printing and back paste printing. Specifically, an adhesion layer is formed on the surface of the to-be-welded point on the surface of one side of the cell, then the cell is turned over, and an adhesion layer is formed on the surface of the to-be-welded point on the surface of the other side of the cell, so that the switching between the front paste printing and the back paste printing of the cell is completed. The battery piece can be turned over, for example, by means of a robot grasping. In the welding process, the front side slurry and the back side slurry can be fused with the welding strip, so that the welding effect is better compared with single-side slurry printing of the battery piece.
In practical application, in order to adapt to the process takt, two slurry printing devices can be arranged, wherein one slurry printing device is used for printing front slurry on the battery piece, and the other slurry printing device is used for printing back slurry on the battery piece. The turnover mechanism is arranged between the two slurry printing devices, the battery piece is turned over through the turnover mechanism, and the battery piece is conveyed from one slurry printing device to the other slurry printing device through the conveying mechanism, so that the slurry printing on the front side and the back side of the battery piece is completed.
The welding of the battery pieces mainly comprises the welding tension of a welding strip, a main grid line and a PAD point of the battery pieces, the tension is improved, the welding effect is also improved, and the string yield among the battery pieces is improved, so that the welding effect of the welding strip, the main grid line and the PAD point of the battery pieces can be promoted by taking the tin alloy in the silver and the tin alloy in the paste printed on the battery pieces as a bridge between the silver paste on the grid line and the tin alloy layer of the welding strip, the welding tension between the silver and the tin alloy can be improved, the welding effect among the battery pieces is improved, the string yield among the battery pieces is improved, and the welding effect of a string welding machine can be fully exerted and the efficiency of a battery assembly is improved just based on the reason; the stability of the series welding machine is improved, and the equipment productivity of the series welding machine is increased. Meanwhile, the silver paste application of the heterojunction battery piece comprises a front main grid line, a back main grid line, a front fine grid line, a back fine grid line, a front PAD point and a back PAD point, and the silver and tin alloy are required to have low-temperature properties.
Based on the battery cluster that above-mentioned heterojunction battery welding method formed, this application embodiment still provides a solar module, includes a plurality of battery cluster, and the battery cluster is including a plurality of heterojunction battery pieces that interconnect, connects through the solder strip between its adjacent heterojunction battery piece, and the test result shows: the tensile force between the welding strip and the PAD point on the grid line is greater than 0.5N, and the solar cell module has better welding tensile force.
The application provides a heterojunction battery welding method, improve prior art's heterojunction battery welding process, increase the process of one section thick liquids printing before the heterojunction battery welds, treat the welding point surface formation adhesion layer at the front of heterojunction battery and back, in welding strip welding process, make adhesion layer and weld the partial melting of area, in order to pass through adjacent thick liquids battery piece and weld the area welded connection, thereby make the welding effect of solder strip and heterojunction battery better under keeping microthermal condition, improve welding tension between them, promote the battery cluster yield, improve battery pack's efficiency, and promote welding machine stability and equipment productivity.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (10)

1. A method of welding a heterojunction battery, comprising the steps of:
forming an adhesion layer on the surface of a to-be-welded point on at least one side surface of a to-be-welded battery piece to obtain a slurry-combined battery piece, wherein the material in the adhesion layer is at least partially the same as the material of the surface of the to-be-welded point and the material of a welding strip for connecting the to-be-welded battery piece;
in a set low-temperature welding temperature range, the adhesion layer and the welding strip are partially melted, so that the adjacent slurry-combined battery pieces are connected through welding of the welding strip;
the material of the surface of the to-be-welded point at least comprises silver and tin alloy, and the slurry for forming the adhesion layer comprises tin alloy powder, soldering flux and other auxiliaries.
2. The heterojunction battery welding method of claim 1, wherein the forming of the adhesion layer to the surface of the point to be welded of the at least one side surface of the cell sheet to be welded comprises:
conveying the battery plate to be welded to a slurry printing platform, and positioning the surface of the welding point to be welded;
calling the slurry to the upper part of the printing screen;
and enabling the slurry to permeate the printing screen plate, and printing on the surface of a to-be-welded point of the battery piece to form an adhesion layer to obtain the slurry-combined battery piece.
3. The heterojunction battery welding method of claim 2, wherein the surface to be welded comprises at least a PAD point on the front side and a PAD point on the back side, the surface to be welded being positioned such that: and respectively positioning the PAD point on the front side and the PAD point on the back side of the battery piece to be welded by adopting an image sensor.
4. The heterojunction battery welding method of claim 3, wherein the surface to be welded further comprises front and back bus bars, the surface to be welded being positioned: and positioning the PAD point on the front surface and/or the main grid line on the front surface of the battery piece to be welded, and the PAD point on the back surface and/or the main grid line on the back surface by adopting the image sensor.
5. A heterojunction battery welding method according to claim 2, wherein said printed mesh plate has a thickness of 5 μm to 50 μm and said adhesion layer has a thickness of 5 μm to 50 μm.
6. The heterojunction battery welding method of claim 1, wherein the welding strip comprises a copper wire and a tin alloy layer positioned at the periphery of the copper wire, and the welding the slurry combined battery piece comprises the following steps:
coating the soldering strip with soldering flux in a soaking mode or a smearing mode;
heating the paste-mixed battery piece to reach a set low-temperature welding temperature range, so that the silver and tin alloy on the surface of the point to be welded in the paste-mixed battery piece is at least partially melted;
aligning the surface of the point to be welded in the adjacent slurry-mixed cell piece with the solder strip, and melting and combining the tin alloy layer on the surface of the solder strip with the tin alloy in the silver and tin alloy in the slurry-mixed cell piece, so that the solder strip and the slurry-mixed cell piece are welded together.
7. The heterojunction battery welding method of claim 6, wherein the soaking manner comprises: the welding strip passes through a soldering flux liquid tank container and is submerged in soldering flux liquid, and the welding strip is drawn by a welding strip drawing mechanism to pass through the soldering flux liquid tank container, so that the soldering flux is attached to the surface of the welding strip;
the smearing mode comprises the following steps: the welding strip passes through the sponge soaked with the soldering flux liquid, is soaked in the soldering flux liquid, and is dragged to pass through the sponge in the soldering flux liquid along with the welding strip stretching mechanism, so that the soldering flux is attached to the surface of the welding strip.
8. A heterojunction battery welding method according to any one of claims 1 to 7, wherein the welding is performed at a low temperature in a range of 170 ℃ to 230 ℃ by combining infrared lamp tube irradiation heat conduction and pin pressing heat conduction.
9. The heterojunction battery welding method of any of claims 1 to 7, wherein the paste further comprises copper powder particles or silver powder particles, the copper powder particles or silver powder particles being added in an amount ranging from 0.5% to 5% by weight of the paste;
the solder strip comprises tin, lead and bismuth, wherein the specific gravity range of tin in the alloy is 40% -46%, the specific gravity range of lead in the alloy is 40% -46%, and the specific gravity range of bismuth in the alloy is 11% -17%;
or the solder strip comprises tin and bismuth, wherein the specific gravity of tin in the alloy ranges from 40% to 46%, and the specific gravity of bismuth in the alloy ranges from 54% to 60%.
10. A heterojunction battery welding method according to any one of claims 1 to 7, wherein after the adhesion layer is formed on the surface of the to-be-welded point on one side of the to-be-welded battery piece, the to-be-welded battery piece is turned over by a turning mechanism and repositioned to form the adhesion layer on the surface of the to-be-welded point on the other side.
CN202110923815.7A 2021-08-12 2021-08-12 Heterojunction battery welding method Pending CN113725304A (en)

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