CN117080313B - Series welding method for reducing bending degree of back contact battery - Google Patents
Series welding method for reducing bending degree of back contact battery Download PDFInfo
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- CN117080313B CN117080313B CN202311316545.9A CN202311316545A CN117080313B CN 117080313 B CN117080313 B CN 117080313B CN 202311316545 A CN202311316545 A CN 202311316545A CN 117080313 B CN117080313 B CN 117080313B
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- back contact
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- 238000003466 welding Methods 0.000 title claims abstract description 149
- 238000000034 method Methods 0.000 title claims abstract description 58
- 238000005452 bending Methods 0.000 title claims abstract description 47
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 168
- 229910052802 copper Inorganic materials 0.000 claims abstract description 159
- 239000010949 copper Substances 0.000 claims abstract description 159
- 238000007747 plating Methods 0.000 claims abstract description 111
- 238000000576 coating method Methods 0.000 claims abstract description 81
- 239000011248 coating agent Substances 0.000 claims abstract description 80
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 67
- 229910052718 tin Inorganic materials 0.000 claims abstract description 64
- 239000002184 metal Substances 0.000 claims abstract description 51
- 229910052751 metal Inorganic materials 0.000 claims abstract description 51
- 229910052709 silver Inorganic materials 0.000 claims abstract description 41
- 239000004332 silver Substances 0.000 claims abstract description 41
- 238000009954 braiding Methods 0.000 claims abstract description 8
- 238000007731 hot pressing Methods 0.000 claims description 107
- 239000010410 layer Substances 0.000 claims description 92
- 229910000679 solder Inorganic materials 0.000 claims description 83
- 239000000463 material Substances 0.000 claims description 46
- 238000005476 soldering Methods 0.000 claims description 29
- 229910052797 bismuth Inorganic materials 0.000 claims description 28
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 28
- QKAJPFXKNNXMIZ-UHFFFAOYSA-N [Bi].[Ag].[Sn] Chemical compound [Bi].[Ag].[Sn] QKAJPFXKNNXMIZ-UHFFFAOYSA-N 0.000 claims description 17
- KHZAWAWPXXNLGB-UHFFFAOYSA-N [Bi].[Pb].[Sn] Chemical compound [Bi].[Pb].[Sn] KHZAWAWPXXNLGB-UHFFFAOYSA-N 0.000 claims description 17
- LQBJWKCYZGMFEV-UHFFFAOYSA-N lead tin Chemical compound [Sn].[Pb] LQBJWKCYZGMFEV-UHFFFAOYSA-N 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 9
- 229910052738 indium Inorganic materials 0.000 claims description 7
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims description 7
- QCEUXSAXTBNJGO-UHFFFAOYSA-N [Ag].[Sn] Chemical compound [Ag].[Sn] QCEUXSAXTBNJGO-UHFFFAOYSA-N 0.000 claims description 6
- PQIJHIWFHSVPMH-UHFFFAOYSA-N [Cu].[Ag].[Sn] Chemical compound [Cu].[Ag].[Sn] PQIJHIWFHSVPMH-UHFFFAOYSA-N 0.000 claims description 6
- OLXNZDBHNLWCNK-UHFFFAOYSA-N [Pb].[Sn].[Ag] Chemical compound [Pb].[Sn].[Ag] OLXNZDBHNLWCNK-UHFFFAOYSA-N 0.000 claims description 6
- JWVAUCBYEDDGAD-UHFFFAOYSA-N bismuth tin Chemical compound [Sn].[Bi] JWVAUCBYEDDGAD-UHFFFAOYSA-N 0.000 claims description 6
- 229910000969 tin-silver-copper Inorganic materials 0.000 claims description 6
- 239000002356 single layer Substances 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 claims description 3
- 238000009941 weaving Methods 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 abstract description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 29
- 238000010438 heat treatment Methods 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 8
- 230000008602 contraction Effects 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000005219 brazing Methods 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004070 electrodeposition Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000004579 marble Substances 0.000 description 2
- 238000003892 spreading Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000007649 pad printing Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
Classifications
-
- 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
- H01L31/04—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 adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
- H01L31/0516—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module specially adapted for interconnection of back-contact solar cells
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K1/00—Soldering, e.g. brazing, or unsoldering
- B23K1/0008—Soldering, e.g. brazing, or unsoldering specially adapted for particular articles or work
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
- B23K35/262—Sn as the principal constituent
-
- 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
- H01L31/04—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 adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
- H01L31/0512—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module made of a particular material or composition of materials
-
- 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
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2101/00—Articles made by soldering, welding or cutting
- B23K2101/36—Electric or electronic devices
Landscapes
- Engineering & Computer Science (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Connection Of Batteries Or Terminals (AREA)
Abstract
The invention belongs to the technical field of back contact battery preparation, and particularly relates to a series welding method for reducing the bending degree of a back contact battery, which comprises the following steps: s1, paving a copper braid with a coating above a main gate electrode on the back of a plurality of back contact battery pieces which are arranged in series and a bonding pad arranged on the main gate electrode, wherein the copper braid with the coating is formed by braiding a plurality of copper wires with the coating after stranding; the number of strands of the copper braided belt with the coating is 4-16, the number of copper wires with the coating contained in each strand is 1-5, the diameter of a single copper wire with the coating is 0.03-0.15mm, the thickness of the coating is 0.01-0.03mm, the coating contains first metal, and the first metal comprises tin and/or silver; s2, carrying out multipoint local hot-press welding on the copper braided belt with the plating layer. The invention has the advantages of obviously reducing the bending degree of the welded battery piece for the back contact battery and keeping enough welding tension.
Description
Technical Field
The invention belongs to the technical field of back contact battery preparation, and particularly relates to a series welding method for reducing the bending degree of a back contact battery.
Background
The positive and negative electrodes of the conventional solar cell (non-back contact cell) are respectively positioned on two sides of the cell, and two ends of the conventional welding strip are respectively connected with the positive electrode and the negative electrode of the adjacent cell. The stress of the front welding strip and the stress of the back welding strip are mutually counteracted, and the whole battery piece is kept straight after series welding without obvious bending phenomenon. The positive electrode and the negative electrode of the back contact battery are positioned on the back, the welding strips are also required to be paved on the back (all the welding strips are welded on the back), the stress of the welding strips cannot be counteracted, and the battery piece is severely bent.
At present, the existing back contact battery series welding process comprises the following steps: spreading a tin-plated brazing strip, spreading a battery piece, adsorbing the battery piece and the welding strip on a heating platform, heating and baking to enable a tin layer of the welding strip to melt and be connected with a back contact battery electrode, and cooling to finish welding. The back contact battery string manufactured by the process has the following defects:
all electrodes of the back contact cell are located on the back of the cell, so all tin-plated braze tape needs to be laid on the back of the cell sheet. However, the thermal expansion coefficient of the battery piece is far smaller than that of the tin-plated copper welding belt, the tin-plated copper welding belt is seriously contracted in the process of heating and cooling after welding, so that the welded back contact battery is seriously bent to the back, and the subsequent battery string laying and lamination processes are extremely difficult.
Disclosure of Invention
The invention aims to overcome the defect that a battery piece is severely bent in back contact battery series welding in the prior art, and provides a series welding method for reducing the bending degree of the back contact battery.
In order to achieve the above object, the present invention provides a series welding method for reducing the bending degree of a back contact battery, comprising the following steps:
s1, paving a copper braid with a coating above a main gate electrode on the back of a plurality of back contact battery pieces which are arranged in series and a bonding pad arranged on the main gate electrode, wherein the copper braid with the coating is formed by braiding a plurality of copper wires with the coating after stranding; the number of strands of the copper braided belt with the coating is 4-16, the number of copper wires with the coating contained in each strand is 1-5, the diameter of a single copper wire with the coating is 0.03-0.15mm, the thickness of the coating is 0.01-0.03mm, the coating contains first metal, and the first metal comprises tin and/or silver;
S2, carrying out multipoint local hot-press welding on the copper braid with the plating layer to enable the copper braid to be welded with the bonding pad, and then cooling.
The conditions for hot press welding according to the present invention include: the hot-press welding temperature is 100-320 ℃, the hot-press pressure is 10-80N, and the hot-press time is 0.2-5s.
In some preferred embodiments of the present invention, the plating layer is a first metal plating layer or a first metal-containing mixed material plating layer, and the doping metal is at least one selected from silver, lead, bismuth, indium, and copper.
In the present invention, preferably, when the first metal is tin, the conditions for thermocompression bonding satisfy:
when the coating is a tin-lead mixed material coating, the hot-press welding temperature T1 is 180-260 ℃;
when the coating is a tin-bismuth-lead mixed material coating, the hot-press welding temperature T2 is 150-200 ℃;
when the coating is a tin-bismuth-silver mixed material coating, the hot-press welding temperature T3 is 100-180 ℃.
When the first metal is tin, it is further preferable that the conditions for thermocompression bonding further satisfy:
for the plating layer is a tin-lead mixed material plating layer, when the number of strands contained in the copper braid with the plating layer is 4-8, the hot-press welding conditions comprise: the hot pressing pressure is 10-60N, the hot pressing time is 1.0-2.5s, and the hot pressing welding temperature is 180-240 ℃; when the number of strands contained in the copper braid with plating is 9-16, the conditions for thermocompression bonding include: the hot pressing pressure is 30-70N, the hot pressing time is 1.8-3.8s, and the hot pressing welding temperature is 200-260 ℃;
For the plating layer is a tin-bismuth-lead mixed material plating layer, when the number of strands contained in the copper braid with the plating layer is 4-8, the hot-press welding conditions comprise: the hot pressing pressure is 10-60N, preferably 20-40N, the hot pressing time is 0.8-1.8s, preferably 0.8-1.5s, and the hot pressing welding temperature is 150-180 ℃; when the number of strands contained in the copper braid with plating is 9-16, the conditions for thermocompression bonding include: the hot pressing pressure is 30-70N, preferably 30-50N, the hot pressing time is 1.0-2.5s, preferably 0.8-2.0s, and the hot pressing welding temperature is 160-200 ℃;
for the plating layer being a tin-bismuth-silver mixed material plating layer, when the number of strands contained in the copper braid with the plating layer is 4-8, the conditions of the thermocompression bonding include: the hot pressing pressure is 10-60N, the hot pressing time is 0.5-1.5s, and the hot pressing welding temperature is 100-160 ℃, preferably 100-120 ℃; when the number of strands contained in the copper braid with plating is 9-16, the conditions for thermocompression bonding include: the hot pressing pressure is 30-70N, the hot pressing time is 0.8-2.0s, and the hot pressing welding temperature is 140-180 ℃.
In other preferred embodiments of the present invention, when the first metal is silver, a solder wire or paste is added between the copper braid having the plating layer and the bonding pad to assist the bonding, the solder wire is melted on the bonding pad in advance when the solder wire is added, and the paste is coated on the bonding pad in advance when the paste is added.
Preferably, the area of the melted solder wire or the area of the coated solder paste is not larger than the area of the bonding pad, and the thickness of the melted solder wire or the thickness of the coated solder paste is respectively 10-100 μm, preferably 20-100 μm.
Wherein the soldering tin wire is a high-temperature lead-free soldering tin wire, a lead-containing soldering tin wire or a low-temperature lead-free soldering tin wire.
Further preferably, when the solder wire is a high-temperature lead-free solder wire, the high-temperature lead-free solder wire comprises a solder wire doped with tin copper, tin silver or tin silver copper alloy, wherein the doping mass ratio of copper is 0-5%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 200-260 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.5-5s.
Further preferably, when the solder wire is a lead-containing solder wire, the lead-containing solder wire comprises a solder wire doped with tin-lead, tin-lead-bismuth or tin-lead-silver, wherein the doping mass ratio of lead is 37% -60%, the doping mass ratio of bismuth is 10% -65%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 150-260 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.5-5s.
Further preferably, when the soldering tin wire is a low-temperature lead-free soldering tin wire, the low-temperature lead-free soldering tin wire comprises soldering tin wires doped with tin bismuth or tin bismuth silver, wherein the doping mass ratio of bismuth is 10% -65%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 100-180 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.2-3s.
Wherein the solder paste is low-temperature solder paste or high Wen Xigao.
Further preferably, when the solder paste is a low-temperature solder paste, the low-temperature solder paste comprises tin bismuth, tin bismuth silver, tin lead bismuth or tin silver lead doped solder paste, wherein the doping mass ratio of lead is 37% -60%, the doping mass ratio of bismuth is 10% -65%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 100-200 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.2-3s.
Further preferably, when the solder paste is a high temperature solder paste, the high temperature solder paste comprises a solder paste doped with tin silver or tin silver copper, wherein the doping mass ratio of silver is 0-10%, and the doping mass ratio of copper is 0.5% -1%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 200-260 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.5-3.5s.
Preferably, the doped metal is selected from lead and/or bismuth, and when the doped metal contains lead, the mass content of lead in the mixed material coating is 15% -60%; when the doped metal contains bismuth, the mass content of bismuth in the mixed material coating is 10-65%.
Preferably, when the first metal in the mixed material coating is tin, the mass content of tin is 5% -65%, the mass content of silver is 0-10%, the mass content of indium is 0-5%, and the mass content of copper is 0-5%.
Preferably, when the first metal in the mixed material coating is silver, the mass content of silver is 5% -65%, and the mass content of copper is 0-1%.
The width of the copper braid with plating layer is preferably 0.5-1.5mm, the thickness is 0.08-0.8mm, and the sectional area is 0.05-0.75mm 2 。
In some embodiments of the present invention, the coated copper braid is a wire or sleeve braid woven using a twill weave method, wherein the wire or sleeve twill weave method is specifically described in part 2 of JB/T6313.2-2011 electrical copper braid.
In some embodiments of the invention, the copper braid with plating is a single layer structure of multi-strand braid.
In some preferred embodiments of the present invention, the end of the copper braid with plating extends beyond the pad of the end of the main gate electrode of the back contact battery sheet in the axial direction of the main gate electrode and outwardly by a distance of 0-5mm, but the end of the copper braid with plating does not exceed the edge of the back contact battery sheet.
In some preferred embodiments of the present invention, the bonding pads are arranged at intervals on the main gate electrode of the back contact battery piece, the thermocompression bonding adopts a mode of respectively thermocompression bonding a plurality of bonding pads through a plurality of thermocompression heads, the thermocompression heads and the bonding pads are in one-to-one correspondence, and the thermocompression heads satisfy: the distance between adjacent hot-pressing heads is 20-100mm.
More preferably, the length of the bonding pad in the direction perpendicular to the axis of the main gate electrode is 0.8-2mm, the width of the bonding pad is 0.2-1mm, the interval between adjacent bonding pads is 20-100mm, and the distance between the bonding pads arranged at both ends of the main gate electrode and the edge of the back contact battery is 3-10mm.
In some preferred embodiments of the present invention, S1 is that a copper braid with a plating layer is laid over a plurality of main gate electrodes on the back surfaces of back contact battery pieces arranged in series and bonding pads arranged thereon, and the plurality of back contact battery pieces are arranged in series along the axis direction of the main gate electrodes; the positive electrode of the main gate electrode of the front back contact battery piece and the negative electrode of the main gate electrode of the back contact battery piece are coaxially arranged in the two adjacent back contact battery pieces connected with the same copper braid belt with a coating, and are connected through the same copper braid belt with a coating.
The beneficial effects are that:
according to the technical scheme, on one hand, the traditional tin-plated copper-clad ribbon is replaced by the copper-clad ribbon with the specific specification, and the copper-clad ribbon with the proper specification has good expansion and contraction capability, so that the stress release of the welded battery string is facilitated; the specific specification of the copper braid is beneficial to furthest reducing the bending degree of the welded battery string under the condition of keeping the power of the assembly unaffected. The low-temperature plating layer (mainly containing tin and/or silver) is adopted, so that the temperature and time of hot-press welding can be reduced as much as possible, the heating of the copper braid belts can be reduced to the greatest extent, and the properly increased number of strands and number of strands are adopted, so that the expansion and contraction capacity of the copper braid belts can be increased, and the bending of the battery strings caused by the contraction of the copper braid belts after cooling can be reduced; on the other hand, the copper braid with the plating layer is subjected to multi-point local hot-press welding, and other areas still keep good expansion capacity of the copper braid, so that stress generated by shrinkage of the copper braid due to temperature change after series welding is released; thereby significantly reducing the degree of bending of the battery cell. In addition, the invention particularly adopts multipoint local hot-press welding to relieve the shrinkage stress brought by the hot-press welding.
For the tinned copper braid, because tin is tetragonal at normal temperature, the tinned copper braid is soft and easy to bend, has good ductility similar to metal copper, but when the heating temperature exceeds 161 ℃, the plating layer is melted and resolidified, the tinned copper braid is converted into an orthorhombic system, and the ductility is poor and fragile; if the whole copper braid is heated, the copper braid is hardened due to solidification of the plating layer, and the expansion and contraction capability is lost; in contrast, the invention particularly carries out multi-point local hot-press welding, only heats the local welding of the copper braid and the bonding pad, and ensures that other parts of the copper braid still maintain good expansion and contraction capability to greatly reduce the bending of the battery string. For silver-plated copper braid, it is preferable to combine solder wires or solder paste, and because of the cooperation of multi-point local hot-press welding, the heating time is short, the temperature is low, and the whole heating of silver-plated copper braid is limited, so that the generated stress is remarkably reduced.
Furthermore, in the preferred scheme of the invention for determining the hot-press welding condition according to the coating material, enough welding tension can be kept under the condition of greatly reducing the hot-press welding temperature, the heating of the copper braid in the welding process is reduced, and the shrinkage deformation of the copper braid in the cooling process after welding is reduced, so that the bending degree of the battery string is greatly reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a side view of a laid back contact battery sheet;
FIG. 2 is a top view of a laid back contact battery sheet;
FIG. 3 is a partial side view of the tin-plated copper braid laid over FIG. 1;
fig. 4 is a top view of the tin-plated copper braid laid over fig. 1;
fig. 5 is a schematic view of a structure for hot-press welding the tin-plated copper braid of fig. 3 by using a hot press head.
Description of the reference numerals
1. The back contact battery piece, 2n, the back main gate electrode negative electrode, 2p, the back main gate electrode positive electrode, 3, the tinned copper braid, 4, the hot pressing head, 5 and the bonding pad.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. Wherein the terms "optional" and "optionally" mean either comprising or not comprising (or may not be present).
The invention provides a series welding method for reducing the bending degree of a back contact battery, which comprises the following steps:
s1, paving a copper braid with a coating above a main gate electrode on the back of a plurality of back contact battery pieces which are arranged in series and a bonding pad arranged on the main gate electrode, wherein the copper braid with the coating is formed by braiding a plurality of copper wires with the coating after stranding;
s2, carrying out multipoint local hot-press welding on the copper braid with the plating layer to enable the copper braid to be welded with the bonding pad, and then cooling.
Wherein the number of strands of the copper braided belt with the coating is 4-16, the number of copper wires with the coating contained in each strand is 1-5, the diameter of a single copper wire with the coating is 0.03-0.15mm, and the thickness of the coating is 0.01-0.03mm. The copper braid with the plating layer of the specification can keep certain expansion capacity after welding so as to release stress caused by deformation generated in the welding process, thereby being beneficial to obviously reducing the bending degree of the battery piece after series welding.
The plating layer contains a first metal, wherein the first metal is a metal with good conductivity, and the first metal comprises tin and/or silver. The plating layer can be a single metal plating layer or a multi-metal alloy plating layer.
It is understood that the copper wire with the plating layer of the invention comprises a copper wire and a plating layer coated on the surface of the copper wire.
In some preferred embodiments of the present invention, the plating layer is a first metal plating layer or a first metal-containing mixed material plating layer, and the doping metal is at least one selected from silver, lead, bismuth, indium, and copper. For example, the plating layer may be a tin-plated copper braid, a silver-plated copper braid, a tin-bismuth-lead mixed material plating layer or a tin-bismuth-silver mixed material plating layer. It is understood that when the first metal comprises silver, the doping metal is selected from at least one of lead, bismuth, indium, copper.
The conditions for hot press welding according to the present invention include: the hot-press welding temperature is 100-320 ℃, the hot-press pressure is 10-80N, and the hot-press time is 0.2-5s. The lower hot-press welding temperature is adopted, and the heating of the copper braid in the welding process is reduced while the enough welding tension is kept, so that the shrinkage deformation of the copper braid in the cooling process after welding is reduced, and the bending degree of the battery string is greatly reduced.
The inventor of the present invention further researches and found that the different plating layers have different and larger influences on the temperature of the thermocompression bonding, thereby influencing the bending degree of the back contact battery. In some preferred embodiments of the present invention, when the first metal is tin, the hot press welding conditions are as follows: when the coating is a tin-lead mixed material coating, the hot-press welding temperature T1 is 180-260 ℃; when the coating is a tin-bismuth-lead mixed material coating, the hot-press welding temperature T2 is 150-200 ℃; when the coating is a tin-bismuth-silver mixed material coating, the hot-press welding temperature T3 is 100-180 ℃. According to the preferred scheme, the hot-press welding temperature and the hot-press time which are as low as possible are adopted for the plating layers of different materials, so that the thermal deformation of the battery piece and the copper braid in the welding process is reduced, and the expansion stress brought by hot-press welding can be fully relieved.
The inventors of the present invention have further studied and found that the hot press pressure and hot press time of hot press welding are related to the specification (particularly the number of strands) of the copper braid having the plating layer and have a large influence, thereby affecting the degree of bending of the back contact battery. In this regard, it is further preferable that, when the first metal is tin, the conditions for thermocompression bonding further satisfy: for the plating layer is a tin-lead mixed material plating layer, when the number of strands contained in the copper braid with the plating layer is 4-8, the hot-press welding conditions comprise: the hot pressing pressure is 10-60N, the hot pressing time is 1.0-2.5s, and the hot pressing welding temperature is 180-240 ℃; when the number of strands contained in the copper braid with plating is 9-16, the conditions for thermocompression bonding include: the hot pressing pressure is 30-70N, the hot pressing time is 1.8-3.8s, and the hot pressing welding temperature is 200-260 ℃.
Further preferably, when the first metal is tin, the conditions for thermocompression bonding further satisfy: for the plating layer is a tin-bismuth-lead mixed material plating layer, when the number of strands contained in the copper braid with the plating layer is 4-8, the hot-press welding conditions comprise: the hot pressing pressure is 10-60N, preferably 10-50N, further preferably 20-40N, the hot pressing time is 0.8-1.8s, preferably 0.8-1.5s, and the hot pressing welding temperature is 150-180 ℃; when the number of strands contained in the copper braid with plating is 9-16, the conditions for thermocompression bonding include: the hot pressing pressure is 30-70N, preferably 30-50N, the hot pressing time is 1.0-2.5s, preferably 1.0-2.0s, and the hot pressing welding temperature is 160-200 ℃.
Further preferably, when the first metal is tin, the conditions for thermocompression bonding further satisfy: for the plating layer being a tin-bismuth-silver mixed material plating layer, when the number of strands contained in the copper braid with the plating layer is 4-8, the conditions of the thermocompression bonding include: the hot pressing pressure is 10-60N, preferably 10-50N, the hot pressing time is 0.5-1.5s, and the hot pressing welding temperature is 100-160 ℃, preferably 100-120 ℃; when the number of strands contained in the copper braid with plating is 9-16, the conditions for thermocompression bonding include: the hot pressing pressure is 30-70N, the hot pressing time is 0.8-2.0s, and the hot pressing welding temperature is 140-180 ℃.
In the above preferred scheme, the hot-press welding temperature, pressure and time in proper ranges are adopted for the coating of different materials, so that the welding heating time is reduced as much as possible on the premise of guaranteeing the welding effect (especially welding tension), and the compression stress caused by hot-press welding can be fully relieved.
When the first metal is tin, it is still further preferable that, for any one of the plating layers, the thermocompression bonding temperature gradually increases with an increase in the number of strands, and satisfies: the increase of the thermocompression bonding temperature is 10-30deg.C, preferably 20-30deg.C per 1 strand. According to the scheme of the invention, which is used for optimizing the hot-press welding temperature, the bending degree of the welded battery piece can be improved as little as possible under the condition of reducing the temperature, and the enough welding tension can be maintained.
In other preferred embodiments of the present invention, when the first metal is silver, a solder wire or paste is added between the copper braid having the plating layer and the bonding pad to assist the bonding, the solder wire is melted on the bonding pad in advance when the solder wire is added, and the paste is coated on the bonding pad in advance when the paste is added. The coating method of the solder paste comprises the following steps: silk screen printing, pad printing, dispensing and the like.
Preferably, the area of the melted solder wire or the area of the coated solder paste is not larger than the area of the bonding pad, and the thickness of the melted solder wire or the thickness of the coated solder paste is respectively 10-100 μm.
Wherein the soldering tin wire is a high-temperature lead-free soldering tin wire, a lead-containing soldering tin wire or a low-temperature lead-free soldering tin wire.
Further preferably, when the solder wire is a high-temperature lead-free solder wire, the high-temperature lead-free solder wire comprises a solder wire doped with tin copper, tin silver or tin silver copper alloy, wherein the doping mass ratio of copper is 0-5%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 200-260 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.5-5s.
Further preferably, when the solder wire is a lead-containing solder wire, the lead-containing solder wire comprises a solder wire doped with tin-lead, tin-lead-bismuth or tin-lead-silver, wherein the doping mass ratio of lead is 37% -60%, the doping mass ratio of bismuth is 10% -65%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 150-260 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.5-5s.
Further preferably, when the soldering tin wire is a low-temperature lead-free soldering tin wire, the low-temperature lead-free soldering tin wire comprises soldering tin wires doped with tin bismuth or tin bismuth silver, wherein the doping mass ratio of bismuth is 10% -65%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 100-180 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.2-3s.
Wherein the solder paste is low-temperature solder paste or high Wen Xigao.
Further preferably, when the solder paste is a low-temperature solder paste, the low-temperature solder paste comprises tin bismuth, tin bismuth silver, tin lead bismuth or tin silver lead doped solder paste, wherein the doping mass ratio of lead is 37% -60%, the doping mass ratio of bismuth is 10% -65%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 100-200 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.2-3s.
Further preferably, when the solder paste is a high temperature solder paste, the high temperature solder paste comprises a solder paste doped with tin silver or tin silver copper, wherein the doping mass ratio of silver is 0-10%, and the doping mass ratio of copper is 0.5% -1%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 200-260 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.5-3.5s.
In the scheme that the solder wires or the solder paste with the preferred specification are matched with the proper hot-press welding conditions, the bending degree of the welded battery piece can be improved as little as possible under the condition of reducing the temperature, and the enough welding tension can be maintained.
The content of each element in the plating layer of the present invention may be in the range conventional in the art. Preferably, the doped metal is selected from lead and/or bismuth, and when the doped metal contains lead, the mass content of lead in the mixed material plating layer is 15% -60%; when the doped metal contains bismuth, the mass content of bismuth in the mixed material coating is 10-65%.
Further preferably, when the first metal in the mixed material plating layer is tin, the mass content of tin is 5% -65%, the mass content of silver is 0-10%, the mass content of indium is 0-5%, and the mass content of copper is 0-5%.
In the invention, preferably, when the coating is a tin-lead mixed material coating, the mass content of lead in the tin-lead mixed material coating is 30% -40%, and the mass content of metallic tin is 60% -70%.
Preferably, when the plating layer is a tin-bismuth-lead mixed material plating layer, the mass content of lead in the tin-bismuth-lead mixed material plating layer is 30% -43%, the mass content of bismuth is 10% -52%, and the mass content of metallic tin is 5% -60%.
Preferably, when the coating is a tin-bismuth-silver mixed material coating, the mass content of silver in the tin-bismuth-silver mixed material coating is 1% -6%, the mass content of bismuth is 50% -60%, and the mass content of metallic tin is 34% -49%.
Preferably, when the first metal in the mixed material coating is silver, the mass content of silver is 5% -65%, and the mass content of copper is 0-1%.
The width of the copper braid with plating layer is preferably 0.5-1.5mm, the thickness is 0.08-0.8mm, and the sectional area is 0.05-0.75mm 2 . According to the preferred scheme, the copper braid strips with lower sectional areas are adopted under the condition that the power of the assembly is not affected, so that sufficient conductivity can be ensured, the expansion and contraction capability and the welding effect are simultaneously considered, and the battery piece bending deformation caused by thermal expansion is relieved in the welding process.
In some embodiments of the invention, the copper braid with plating is a wire or sleeve braid woven by a twill weave method. The linear or sleeve-shaped twill weaving method is specifically disclosed in part 2 of JB/T6313.2-2011 electrotechnical copper weaving line.
In some embodiments of the invention, the copper braid with plating is a single layer structure of multi-strand braid. According to the preferred scheme, the stretching capacity of the twill weave structure can be utilized, so that the stress generated by thermal stretching after welding is reduced, and the bending deformation of the battery piece is reduced.
In some preferred embodiments of the present invention, the end of the copper braid with plating extends beyond the pad of the end of the main gate electrode of the back contact battery sheet in the axial direction of the main gate electrode and outwardly by a distance of 0-5mm, but the end of the copper braid with plating does not exceed the edge of the back contact battery sheet. According to the preferred scheme, enough welding tolerance can be reserved, and welding yield and product reliability are guaranteed more conveniently.
In the present invention S1, the connection structure between the main gate electrode and the pads disposed thereon may be performed according to the prior art, for example, the main gate electrode is provided with pads disposed at intervals along its axis. On the battery piece, the positive electrode positions of adjacent main gate electrodes correspond to the negative electrode positions of the main gate electrodes and are arranged in pairs.
In some preferred embodiments of the present invention, the copper braid with plating layer is laid on the main gate electrode on the back of the plurality of serially arranged back contact battery pieces and the bonding pads arranged thereon in S1, and the plurality of back contact battery pieces are serially arranged along the axis direction of the main gate electrode.
Preferably, the positive electrode of the main gate electrode of the previous back contact battery piece and the negative electrode of the main gate electrode of the next back contact battery piece are coaxially arranged in the two adjacent back contact battery pieces connected with the same copper braid belt with the coating, and are connected through the same copper braid belt with the coating.
In some embodiments of the invention, S1 specifically comprises: the back of the back contact battery piece is paved on the heating platform upwards, the copper braid with the plating layer is paved above the back of the back contact battery piece, and the positions of the copper braid with the plating layer are respectively overlapped with the positive electrode of the main gate electrode of the adjacent front back contact battery and the negative electrode of the main gate electrode of the back contact battery.
In some preferred embodiments of the present invention, the bonding pads are arranged at intervals on the main gate electrode of the back contact battery piece, and the thermocompression bonding adopts a mode of respectively thermocompression bonding a plurality of bonding pads through a plurality of thermocompression heads, wherein the thermocompression heads are in one-to-one correspondence with the bonding pads. Preferably the thermal head is located at the center of the corresponding pad.
Further preferably, the thermo-compression head satisfies: the spacing between adjacent hot rams is in the range 20 to 100mm, more preferably 40 to 80mm.
More preferably, the length of the bonding pad in the direction perpendicular to the axis of the main gate electrode is 0.8-2mm, the width of the bonding pad is 0.2-1mm, the interval between adjacent bonding pads is 20-100mm, and the distance between the bonding pads arranged at both ends of the main gate electrode and the edge of the back contact battery is 3-10mm.
In the S2 of the invention, the copper braid with the coating is subjected to multi-point local hot-press welding to ensure that the position of a hot-press head of the hot-press welding is consistent with the position of a main grid electrode pad on a battery piece in the welding of the bonding pad, and the hot-press head extrudes the copper braid with the coating on the bonding pad, heats up to melt tin, and then cools down to resolidify the tin; and (3) welding the copper braid with the plating layer and the bonding pad. The hot pressing head comprises hot pressing the two ends and the middle parts of the copper braid with the coating, so that the copper braid with the coating in the heating area is welded with the positive electrode and the negative electrode of the back contact battery.
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
Example 1
A series welding method for reducing bending degree of back contact battery comprises the following steps:
1. as shown in fig. 1 and 2, back contact battery pieces 1 are sequentially arranged on a heating platform; the back of the back contact battery piece 1 is upward, and is provided with a plurality of main grid electrodes, bonding pads 5 are arranged on the main grid electrodes at intervals, and the positions of the positive electrodes 2p of the main grid electrodes of the adjacent battery pieces correspond to the positions of the negative electrodes 2n of the main grid electrodes and are positioned on the same axis; the length of the pad 5 is 1mm and the width of the pad 5 is 0.3mm. The adjacent pads 5 are spaced apart by 30mm in the main gate electrode axial direction. The pads 5 disposed at both ends of the main gate electrode are 5mm from the edge of the battery cell.
2. As shown in fig. 3 and 4, tin-plated copper braid 3 with tin, bismuth and silver as plating layers is laid on the back contact battery pieces 1 arranged in series, and the tin, bismuth and silver contents are 42wt%, 55wt% and 3wt%, respectively, and are overlapped with the positive electrode 2p of the main gate electrode on the back surface of the adjacent front back contact battery piece 1 and the negative electrode 2n of the main gate electrode on the back surface of the back contact battery piece 1 in sequence. The width of the tinned copper braid 3 is 1.2mm, the thickness is 0.3mm, and the sectional area is 0.11mm 2 . The tinned copper braid 3 is braided into a ribbon shape (i.e., a thread shape) by a twill braiding method. The ends of the tin-plated copper braid 3 extend outwardly beyond the pads 5 of the main gate electrode ends of the back contact battery pieces 1 by a distance of 3mm, but the ends of the tin-plated copper braid 3 do not extend beyond the edges of the back contact battery pieces 1.
The tinned copper braid 3 is a single-layer structure formed by braiding a plurality of tinned copper wires after stranding, the number of strands is 8, the number of the tinned copper wires contained in each strand is 5, the diameter of a single tinned copper wire is 0.06mm, and the thickness of a plating layer is 0.02mm.
3. As shown in fig. 5, the hot-pressing heads 4 are used to hot-press the two ends and the middle of the tin-plated copper braid 3, so that the tin-plated copper braid 3 in the heating area is welded with the positive electrode 2p and the negative electrode 2n of the back-contact battery; the spacing between adjacent hot rams 4 is 30mm. For the tin-plated copper braid 3 (single metal plating layer), the hot press welding temperature was 130 ℃, the hot press pressure was 40N, and the hot press time was 1.2s.
4. And cooling the hot pressing head to finish welding.
Example 2
The procedure of example 1 was followed, except that the number of strands was 4, and the thermocompression bonding conditions were modified as follows: the hot-press welding temperature is 100 ℃, the hot-press pressure is 40N, and the hot-press time is 1.0s.
Example 3
The procedure of example 1 was followed, except that the number of strands was 15, and the thermocompression bonding conditions were modified as follows: the hot-press welding temperature is 130 ℃, the hot-press pressure is 50N, and the hot-press time is 1.8s.
Example 4
The procedure of example 1 was followed, except that the number of strands was unchanged and the thermocompression bonding conditions were modified as follows: the hot-press welding temperature is 150 ℃, the hot-press pressure is 40N, and the hot-press time is 1.2s.
Example 5
The procedure of example 1 was followed, except that the number of strands was unchanged and the thermocompression bonding conditions were modified as follows: the hot-press welding temperature is 110 ℃, the hot-press pressure is 40N, and the hot-press time is 1.2s.
Example 6
The method of example 1 was performed with the difference that the tin-bismuth-lead mixed material plating layer was used as the plating layer in the tin-copper-plated braid, the tin, bismuth, and lead contents were 16wt%, 52 wt wt%, and 32wt%, respectively, and the thermocompression bonding conditions were modified as follows: the hot press welding temperature T2 is 150 ℃, the hot press pressure is 40N, and the hot press time is 1.5 s.
Example 7
The procedure of example 6 was followed, except that the number of strands was 4, and the thermocompression bonding conditions were modified as follows: the hot-press welding temperature is 150 ℃, the hot-press pressure is 60N, and the hot-press time is 1.8s.
Example 8
The process of example 6 was followed, except that the number of strands was 15, and the thermocompression bonding conditions were modified as follows: the hot-press welding temperature is 170 ℃, the hot-press pressure is 60N, and the hot-press time is 2.5s.
Example 9
The method of example 1 was conducted with the difference that, when the plating layer in the tin-plated copper braid was a tin-lead mixed material plating layer, the tin and lead contents were 40wt% and 60wt%, respectively, and the thermocompression bonding conditions were modified as follows: the hot-press welding temperature T3 is 220 ℃, the hot-press pressure is 60N, and the hot-press time is 2.5s.
Example 10
The procedure of example 9 was carried out with the difference that the number of strands was 15 and the thermocompression bonding temperature was 220 ℃.
Example 11
The procedure of example 9 was carried out with the difference that the number of strands was 15 and the thermocompression bonding temperature was 240 ℃.
Example 12
The procedure of example 9 was carried out with the difference that the number of strands was unchanged and the thermocompression bonding temperature was modified to 200 ℃.
Example 13
The method according to example 1 was performed by adding a solder wire between the copper braid having a plating layer and the pad to assist welding in thermocompression bonding, the solder wire being melted in advance on the pad and having a melted area smaller than the pad area and a thickness of 30 μm, the solder wire being a low temperature lead-free solder wire having a composition of tin-bismuth-silver ratio of 35%, 60%, 5%, respectively, the thermocompression bonding temperature of 130 ℃, the thermocompression bonding pressure of 40N, and the thermocompression bonding time of 1.5s.
Example 14
The method of example 13 was conducted with the difference that the solder wires were lead-containing solder wires having a tin-bismuth-lead ratio of 23%, 40% and 37%, respectively, and the thermocompression bonding temperature was 160 ℃, the thermocompression bonding pressure was 40N, and the thermocompression bonding time was 1.8s.
Example 15
The method according to example 1 was performed with the difference that the plating layer of the copper braid was silver, and a solder paste was added between the copper braid having the plating layer and the pad to aid the soldering at the time of thermocompression bonding, and the solder paste was previously coated on the pad and the area after coating was smaller than the area of the pad and the coating thickness was 30 μm at the time of adding the solder paste; the solder paste is low-temperature solder paste, the components are tin, bismuth and silver, the proportions of which are 35%, 60% and 5%, respectively, the hot-press welding temperature is 130 ℃, the hot-press pressure is 40N, and the hot-press time is 1.5s.
Example 16
The procedure of example 15 was followed, except that the solder paste coating thickness was 10. Mu.m.
Comparative example 1
The procedure of example 1 was carried out, except that a tin-plated copper tape (which is a sheet-like copper tape having a tin-plated coating) of 0.23mm×1mm in specification was used instead of a tin-plated copper tape braid, and that the plating layer was tin-bismuth-silver.
Comparative example 2
By the method of example 1, the difference is that The number of strands is 24, the thickness of the corresponding obtained plating layer is 0.02mm, the thickness of the copper braid is 0.8mm, and the sectional area is 0.34mm 2 。
Comparative example 3
The process according to example 1 was carried out with the difference that the number of strands was 3, the thickness of the corresponding plating obtained was 0.02mm, the thickness of the copper braid was 0.3mm, and the cross-sectional area was 0.042mm 2 。
Comparative example 4
The process according to example 1 was carried out, except that the number of copper wires having a plating layer contained in each strand was 12, the thickness of the corresponding resultant plating layer was 0.02mm, the thickness of the copper braid was 0.7mm, and the sectional area was 0.27mm 2 。
Comparative example 5
The process according to example 1 is carried out with the difference that the diameter of the individual coated copper wire is 0.20mm, the thickness of the corresponding coating obtained is 0.02mm, the thickness of the copper braid is 0.6mm, the cross-sectional area is 0.63mm 2 。
Test case
The battery strings obtained in the examples and the comparative examples are subjected to bending degree performance test and welding tension test, wherein the bending degree test method comprises the steps of standing a battery piece on a marble platform with a concave surface downward, and measuring the average distance between the middle of the battery piece and a marble table surface by a thickness layer; the welding tension test method is that the welded battery piece is clamped, the end part of the welding belt is turned over by 180 degrees and connected to a tension meter, the average value of the tension peak value of each welding disc is collected at a constant speed of 1.5mm/s, and the test result is shown in table 1.
TABLE 1
From the above results, it can be seen that, compared with the comparative example, the scheme of the embodiment of the invention can manufacture the battery string by adopting the copper braid belts with different specifications and matching with the proper hot-press welding conditions, thereby remarkably reducing the bending degree of the back contact battery and keeping the proper large welding tension. In the scheme of the comparative example, the traditional tinning brazing belts are adopted, or the adopted copper braiding belts are unreasonable in specification, so that the bending degree of the battery piece is too large or the welding tension value is too small, and the back contact battery string with small bending degree and stability and reliability cannot be manufactured.
Furthermore, according to the embodiment 1 and the embodiment 3 of the present invention, the embodiment 1 scheme of the present invention, in which the copper braid with the preferred specification is matched with the appropriate hot-press welding conditions, can greatly reduce the bending degree of the battery piece, and simultaneously maintain the welding tension as large as possible, which is more beneficial to manufacturing the back contact battery string with small bending degree and stability and reliability.
Furthermore, according to the embodiment 6 and the embodiments 7 to 8 of the present invention, the embodiment 6 scheme of the present invention, in which the copper braid with the preferred specification is matched with the appropriate hot-press welding conditions, can further reduce the bending degree of the battery piece, and simultaneously maintain the welding tension as large as possible, which is more favorable for manufacturing the back contact battery string with small bending degree and stability and reliability.
Furthermore, according to the embodiment 9 and the embodiment 10 of the present invention, it can be seen that by adopting the embodiment 9 scheme of the present invention, in which the copper braid with the preferred specification is matched with the appropriate hot-press welding condition, the bending degree of the battery piece can be greatly reduced, and meanwhile, the welding tension can be kept as large as possible, which is more favorable for manufacturing the back contact battery string with small bending degree and stability and reliability.
Further, according to the embodiments 13, 14, 15 and 16 of the present invention, the preferred specification copper braid is adopted in combination with the embodiment scheme of the suitable thermocompression bonding conditions, so that the bending degree of the battery piece can be greatly reduced, and meanwhile, the welding tension can be kept as large as possible, which is more beneficial to manufacturing the back contact battery string with small bending degree and stability and reliability.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (13)
1. A method of series welding for reducing the degree of bending of a back contact battery, comprising the steps of:
s1, paving a copper braid with a coating above a main gate electrode on the back of a plurality of back contact battery pieces which are arranged in series and a bonding pad arranged on the main gate electrode, wherein the copper braid with the coating is formed by braiding a plurality of copper wires with the coating after stranding; the number of strands of the copper braided belt with the coating is 4-16, the number of copper wires with the coating contained in each strand is 1-5, the diameter of a single copper wire with the coating is 0.03-0.15mm, the thickness of the coating is 0.01-0.03mm, the coating contains first metal, and the first metal comprises tin and/or silver;
s2, carrying out multipoint local hot-press welding on the copper braid with the plating layer to enable the copper braid to be welded with the bonding pad, and then cooling; the conditions of the thermocompression bonding include: the hot-press welding temperature is 100-320 ℃, the hot-press pressure is 10-80N, and the hot-press time is 0.2-5s.
2. The method of claim 1, wherein the plating is a first metal plating or a plating of a mixed material containing a first metal and a doped metal, and the doped metal is at least one of silver, lead, bismuth, indium, and copper.
3. The method for cross-welding to reduce the bending degree of a back contact battery according to claim 2, wherein when the first metal is tin, the conditions for hot press welding are as follows:
when the coating is a tin-lead mixed material coating, the hot-press welding temperature T1 is 180-260 ℃;
when the coating is a tin-bismuth-lead mixed material coating, the hot-press welding temperature T2 is 150-200 ℃;
when the coating is a tin-bismuth-silver mixed material coating, the hot-press welding temperature T3 is 100-180 ℃.
4. A method of series welding for reducing the degree of bending of a back contact battery according to claim 3, wherein the conditions of the thermocompression welding are further satisfied:
for the plating layer is a tin-lead mixed material plating layer, when the number of strands contained in the copper braid with the plating layer is 4-8, the hot-press welding conditions comprise: the hot pressing pressure is 10-60N, the hot pressing time is 1.0-2.5s, and the hot pressing welding temperature is 180-240 ℃; when the number of strands contained in the copper braid with plating is 9-16, the conditions for thermocompression bonding include: the hot pressing pressure is 30-70N, the hot pressing time is 1.8-3.8s, and the hot pressing welding temperature is 200-260 ℃;
for the plating layer is a tin-bismuth-lead mixed material plating layer, when the number of strands contained in the copper braid with the plating layer is 4-8, the hot-press welding conditions comprise: the hot pressing pressure is 10-60N, the hot pressing time is 0.8-1.8s, and the hot pressing welding temperature is 150-180 ℃; when the number of strands contained in the copper braid with plating is 9-16, the conditions for thermocompression bonding include: the hot pressing pressure is 30-70N, the hot pressing time is 1.0-2.5s, and the hot pressing welding temperature is 160-200 ℃;
For the plating layer being a tin-bismuth-silver mixed material plating layer, when the number of strands contained in the copper braid with the plating layer is 4-8, the conditions of the thermocompression bonding include: the hot pressing pressure is 10-60N, the hot pressing time is 0.5-1.5s, and the hot pressing welding temperature is 100-160 ℃; when the number of strands contained in the copper braid with plating is 9-16, the conditions for thermocompression bonding include: the hot pressing pressure is 30-70N, the hot pressing time is 0.8-2.0s, and the hot pressing welding temperature is 140-180 ℃.
5. The method according to claim 2, wherein when the first metal is silver, solder wires or solder paste is added between the copper braid having the plating layer and the bonding pad to assist the bonding, the solder wires are melted on the bonding pad in advance when the solder wires are added, and the solder paste is coated on the bonding pad in advance when the solder paste is added.
6. The method for series welding for reducing the bending degree of the back contact battery according to claim 5, wherein the melted area of the solder wire or the coated area of the solder paste is not larger than the area of the bonding pad, and the melted thickness of the solder wire or the coated thickness of the solder paste is respectively 10-100 μm.
7. The method for series welding for reducing the bending degree of a back contact battery according to claim 5, wherein the solder wire is a high-temperature lead-free solder wire, a lead-containing solder wire or a low-temperature lead-free solder wire;
when the soldering tin wire is a high-temperature lead-free soldering tin wire, the high-temperature lead-free soldering tin wire comprises a soldering tin wire doped with tin copper, tin silver or tin silver copper alloy, wherein the doping mass ratio of copper is 0-5%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 200-260 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.5-5s;
when the soldering tin wire is a lead-containing soldering tin wire, the lead-containing soldering tin wire comprises a soldering tin wire doped with tin lead, tin lead bismuth or tin lead silver, wherein the doping mass ratio of lead is 37% -60%, the doping mass ratio of bismuth is 10% -65%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 150-260 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.5-5s;
when the soldering tin wire is a low-temperature lead-free soldering tin wire, the low-temperature lead-free soldering tin wire comprises soldering tin wires doped with tin bismuth or tin bismuth silver, wherein the doping mass ratio of bismuth is 10% -65%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 100-180 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.2-3s;
The solder paste is low-temperature solder paste or high Wen Xigao;
when the tin paste is low-temperature tin paste, the low-temperature tin paste comprises tin bismuth, tin bismuth silver, tin lead bismuth or tin silver lead doped tin paste, wherein the doping mass ratio of lead is 37% -60%, the doping mass ratio of bismuth is 10% -65%, and the doping mass ratio of silver is 0-10%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 100-200 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.2-3s;
when the tin paste is high-temperature tin paste, the high-temperature tin paste comprises tin silver or tin silver copper doped tin paste, wherein the doping mass ratio of silver is 0-10%, and the doping mass ratio of copper is 0.5% -1%; and the conditions of the thermocompression bonding include: the hot pressing temperature is 200-260 ℃, the hot pressing pressure is 10-80N, and the hot pressing time is 0.5-3.5s.
8. The series welding method for reducing the bending degree of the back contact battery according to claim 2, wherein the doping metal is selected from lead and/or bismuth, and when the doping metal contains lead, the mass content of lead in the mixed material plating layer is 15% -60%; when the doped metal contains bismuth, the mass content of bismuth in the mixed material plating layer is 10% -65%; when the first metal in the mixed material coating is tin, the mass content of tin is 5-65%, the mass content of silver is 0-10%, the mass content of indium is 0-5%, and the mass content of copper is 0-5%; when the first metal in the mixed material coating is silver, the mass content of silver is 5-65%, and the mass content of copper is 0-1%;
And/or the number of the groups of groups,
the width of the copper braided belt with the plating layer is 0.5-1.5mm, the thickness is 0.08-0.8mm, and the sectional area is 0.05-0.75mm 2 。
9. The method for series welding for reducing the bending degree of the back contact battery according to claim 1, wherein the copper braid with the plating layer is a wire-shaped or sleeve-shaped braid woven by a twill weaving method;
and/or the number of the groups of groups,
the copper braid with the plating layer is of a single-layer structure formed by braiding a plurality of strands.
10. A method of series welding for reducing the degree of bending of a back contact cell according to claim 1, wherein the end of the plated copper braid extends beyond the bonding pad at the end of the main gate electrode of the back contact cell and outwardly by a distance of 0-5mm in the axial direction of the main gate electrode, but the end of the plated copper braid does not exceed the edge of the back contact cell.
11. The series welding method for reducing the bending degree of the back contact battery according to claim 1, wherein the bonding pads are arranged on the main gate electrode of the back contact battery piece at intervals, the hot-press welding adopts a mode of respectively hot-pressing a plurality of bonding pads through a plurality of hot-press heads, the hot-press heads are in one-to-one correspondence with the bonding pads, and the hot-press heads satisfy the following conditions: the distance between adjacent hot-pressing heads is 20-100mm.
12. The method for reducing the bending degree of the back contact battery according to claim 11, wherein the length of the bonding pad in the direction perpendicular to the axis of the main gate electrode is 0.8-2mm, the width of the bonding pad is 0.2-1mm, the interval between adjacent bonding pads is 20-100mm, and the distance between the bonding pads disposed at both ends of the main gate electrode and the edge of the back contact battery is 3-10mm.
13. The method for series welding for reducing the bending degree of back contact cells according to claim 1, wherein S1, the copper braid with plating layer is laid over the main gate electrodes on the back surfaces of the plurality of back contact cells arranged in series and the bonding pads arranged thereon, and the plurality of back contact cells are arranged in series along the axis direction of the main gate electrodes; the positive electrode of the main gate electrode of the front back contact battery piece and the negative electrode of the main gate electrode of the back contact battery piece are coaxially arranged in the two adjacent back contact battery pieces connected with the same copper braid belt with a coating, and are connected through the same copper braid belt with a coating.
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Citations (4)
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|---|---|---|---|---|
| JP2008182171A (en) * | 2006-12-28 | 2008-08-07 | Hitachi Cable Ltd | Solder-plated wire for solar cell and manufacturing method thereof, and solar cell |
| CN101924154A (en) * | 2009-05-25 | 2010-12-22 | 夏普株式会社 | Solar module and the electronic equipment that carries this solar module |
| WO2017155224A1 (en) * | 2016-03-08 | 2017-09-14 | 엘에스전선 주식회사 | Stranded conductor wire for solar cell module |
| CN218730981U (en) * | 2022-08-18 | 2023-03-24 | 福建钧石能源有限公司 | Back electrode solar cell unit and battery module |
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| CN103548152A (en) * | 2011-03-31 | 2014-01-29 | Ats自动化加工系统公司 | Photovoltaic cell tab and method and system for forming photovoltaic cell tabs |
| US20220310858A1 (en) * | 2020-05-21 | 2022-09-29 | Jingao Solar Co., Ltd. | Back Contact Type Solar Cell Module and Preparation Method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008182171A (en) * | 2006-12-28 | 2008-08-07 | Hitachi Cable Ltd | Solder-plated wire for solar cell and manufacturing method thereof, and solar cell |
| CN101924154A (en) * | 2009-05-25 | 2010-12-22 | 夏普株式会社 | Solar module and the electronic equipment that carries this solar module |
| WO2017155224A1 (en) * | 2016-03-08 | 2017-09-14 | 엘에스전선 주식회사 | Stranded conductor wire for solar cell module |
| CN218730981U (en) * | 2022-08-18 | 2023-03-24 | 福建钧石能源有限公司 | Back electrode solar cell unit and battery module |
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