Solder strip for photovoltaic module with low thermal expansion coefficient and preparation method of solder strip

Abstract

The invention discloses a solder strip for a photovoltaic module with a low thermal expansion coefficient and a preparation method of the solder strip, and belongs to the field of photovoltaic device manufacturing. The alloy material comprises the following raw materials: metal and negative thermal expansion alloy particles, the welding strip comprises the alloy material and a metal coating. The solder strip material has a low thermal expansion coefficient, thermal stress generated in the welding process can be effectively reduced, welding failure of the solder strip is avoided, and the component reject ratio is reduced; the solder strip is excellent in electrical conductivity and thermal conductivity, so that the efficient working state of the solar cell is ensured; the material is low in cost, simple in preparation process and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic device manufacturing, specifically to a low thermal expansion coefficient photovoltaic module solder strip and its preparation method. Background Technology

[0002] In existing photovoltaic (PV) modules, solder ribbon is a crucial material, primarily used to connect solar cells and transmit electrical energy. Its performance directly affects the reliability and lifespan of the solar cells. However, existing solder ribbon materials are mainly tin-plated copper ribbons, which have a high coefficient of thermal expansion. Drastic temperature changes during the soldering process and diurnal temperature variations during module operation can generate significant thermal stress between the solder ribbon and the solar cells, causing the cells to bend or even develop microcracks, ultimately leading to an increased module defect rate.

[0003] Currently, the industry mainly alleviates the problem of thermal stress by optimizing welding processes or using buffer layers, but these methods cannot fundamentally solve the problem of the large coefficient of thermal expansion of the solder strip. Therefore, there is an urgent need for a new type of solder strip material with a low coefficient of thermal expansion, so as to have low volume change during welding, reduce the generation of thermal stress, effectively improve the reliability of the solder strip connection, and further reduce the defect rate of components.

[0004] This invention provides a solder ribbon material with a low coefficient of thermal expansion. By adjusting the composition of the solder ribbon material, its coefficient of thermal expansion is reduced, thereby reducing the thermal stress generated during high-temperature welding, reducing the risk of cell bending and microcracks, avoiding solder ribbon connection failure, and improving the long-term stability and reliability of solar cells. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a low thermal expansion coefficient photovoltaic module solder strip and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A first aspect of the present invention relates to an alloy material comprising the following raw materials:

[0008] Metals; and negative thermal expansion alloy particles, .

[0009] Optionally, in the alloy material, the negative thermal expansion alloy particles account for 0.5wt% to 1.5wt%, and the metal is copper.

[0010] A second aspect of the present invention relates to a solder strip comprising:

[0011] The aforementioned alloy materials,

[0012] And, metal plating.

[0013] Optionally, the metal plating includes at least one of tin, lead, and bismuth.

[0014] A third aspect of the present invention relates to a method for preparing an alloy material, comprising the following steps:

[0015] Mn, Co, Ge and Si were used to prepare [the product] by vacuum arc melting. Alloy ingots, x = 0.07~0.20;

[0016] The alloy ingot is crushed and ground to obtain alloy particles;

[0017] The alloy material is obtained by mixing metal particles and metal powder and then hot-pressing them under vacuum.

[0018] Optionally, the alloy ingot is annealed at 850 degrees Celsius after preparation.

[0019] Optionally, before obtaining alloy particles by crushing and grinding the alloy ingot, six parts of negative thermal expansion alloy particles with values ​​of 0.07, 0.09, 0.11, 0.14, 0.17, and 0.20 respectively are taken. Mix by equal weight.

[0020] Optionally, the vacuum hot pressing conditions are: 900±5℃, 3±0.5GPa, vacuum hot pressing for 5~15 minutes.

[0021] A fourth aspect of the present invention relates to a method for manufacturing solder strips, comprising the following steps:

[0022] The steps of the above-mentioned alloy material preparation method;

[0023] After the alloy material is processed and shaped, an outer metal layer is plated to obtain the welding strip.

[0024] A fifth aspect of the present invention relates to a photovoltaic module comprising: the alloy material described above, the solder strip described above, an alloy material obtained by the alloy material obtained by the above method, or a solder strip obtained by the above method.

[0025] The beneficial effects of this invention are:

[0026] The welding strip material of the present invention has a low coefficient of thermal expansion, which can effectively reduce the thermal stress generated during the welding process, avoid welding strip failure, and reduce the component defect rate.

[0027] The solder ribbon has excellent electrical and thermal conductivity, ensuring the high-efficiency operation of the solar cell;

[0028] The materials used in this invention are low-cost, the preparation process is simple, and it is suitable for large-scale production. Attached Figure Description

[0029] The invention will now be further described with reference to the accompanying drawings.

[0030] Figure 1 For the purposes of this application Thermal expansion curve of the alloy;

[0031] Figure 2 For the purposes of this application Particle size distribution after alloy ball milling;

[0032] Figure 3 For the purposes of this application XRD patterns of the alloy, Cu, and the low thermal expansion Cu alloy composite of the present invention;

[0033] Figure 4 For metallic Cu and Thermal expansion curve of alloy / Cu composite material;

[0034] Figure 5 Statistics on defect rates for different solder strip production components. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In some embodiments of the present invention, a solder strip is disclosed, which may include the following raw material: metallic Cu; Negative thermal expansion alloy particles; Sn coating (mainly containing trace metals such as Pb and Bi).

[0037] In some instances, The preparation method of negative thermal expansion alloy particles is as follows:

[0038] Mn, Co, Ge, and Si elements were weighed according to their molar mass ratios, and the mixture was prepared by vacuum arc melting. To ensure alloy homogeneity, the alloy ingot was vacuum annealed at 850℃ for 5 days. The thermal expansion properties of the sample were characterized using a thermal expansion meter (Linseis DIL L75 VS). The meter's working principle is as follows: the sample with parallel upper and lower surfaces is placed on a fixed quartz base of the instrument. The movable upper quartz rod is gently placed against the sample, and a force of 10 mN is applied to secure the sample. Then, heating and cooling tests are conducted under inert gas protection. When the linear length of the sample changes slightly, the differential transformer monitors the change in sample size in real time, and the instrument software simultaneously records data such as strain, temperature, and stress. The thermal expansion coefficient of the standard quartz is calibrated before each test to facilitate subsequent correction of the test sample data. During the test, the heating and cooling rates were set to 5 K / min. The negative thermal expansion curve of this alloy composition is shown in the attached figure. Figure 1 As shown;

[0039] Will The alloy blocks obtained after mechanical crushing of the alloy ingot are placed in a planetary ball mill and milled for 2-3 hours at a ball-to-material ratio of 6-9:1 and a rotation speed of 80-100 r / min to obtain... The size distribution range of the negative thermal expansion alloy particles is shown in the attached figure. Figure 2 As shown;

[0040] Six kinds mixed in equal weight ratio Alloy particles are mixed with Cu powder in a ball mill at different weight ratios. The mixture is then ball-milled for 0.5 to 1 hour at a ball-to-powder ratio of 7 to 10:1 and a rotation speed of 80 to 100 r / min to ensure uniform mixing of the alloy components.

[0041] Six kinds of mixtures in equal weight ratio Alloy particles and Cu powder are loaded into a mold and placed in a vacuum hot press furnace, where a vacuum is drawn. During the hot pressing process, if the temperature and pressure become too high... Alloy particles can undergo interfacial reactions with Cu. Too low a temperature and pressure will lead to a decrease in the density and mechanical properties of the composite material. Therefore, this invention selects vacuum hot pressing at 900±5℃ and 3±0.5GPa for 5~15 minutes, followed by cooling to room temperature, to prepare the composite material. Alloy particles / Cu composite material.

[0042] X-ray diffraction (XRD) was performed on the alloy powder and composite material, as shown in the attached figure. Figure 3 As shown, it can be observed that, with The increase in the proportion of negative thermal expansion alloys in composite materials The characteristic diffraction peaks of the alloy gradually increase and become stronger.

[0043] In some instances, different proportions of the above were added. The thermal expansion properties of the Cu-based composite material with alloy particles were characterized, and the results are shown in the attached figure. Figure 4 As shown, with With the increase of the alloy particle ratio, the coefficient of thermal expansion of Cu-based composite materials gradually decreases, from the initial... It has dropped to The coefficient of thermal expansion decreased by approximately 26.9%.

[0044] The Cu-based composite material is rolled to obtain weld strips with circular or rectangular cross-sections, and a 5-10 μm Sn layer is deposited on the surface to achieve good welding performance. Figure 5 As shown, the defect rate of produced components decreased from the initial 43.2% to 13.3%.

[0045] Example 1:

[0046] 1. Preparation of alloy particles:

[0047] (1) Weigh Mn, Co, Ge and Si elements (all with a purity greater than 99.9%) according to the molar mass ratio, and prepare by vacuum arc melting. To ensure uniform composition, the alloy ingot was vacuum annealed at 850℃ for 5 days. The negative thermal expansion curve of the alloy composition is shown in the attached figure. Figure 1 As shown;

[0048] (2) The alloy blocks, after mechanical crushing of the alloy ingot, are placed in a planetary ball mill and milled for 2 hours at a ball-to-material ratio of 8:1 and a rotation speed of 95 r / min to obtain... The size distribution range of the alloy particles is shown in the attached figure. Figure 2 As shown.

[0049] 2. Preparation of alloy particle / Cu-based composite materials:

[0050] (1) Mix six kinds of ingredients in equal weight ratios Alloy particles according to The weight ratio of the powder to pure Cu powder is mixed in a ball mill, and the mixture is ball-milled for 1 hour at a ball-to-powder ratio of 9:1 and a rotation speed of 90 r / min to ensure that the alloy components are uniformly mixed.

[0051] (2) Mix Alloy particles / Cu powder were loaded into a mold and placed in a vacuum hot press furnace. A vacuum was drawn, and the mixture was vacuum-pressed at 900℃ and 3GPa for 8 minutes. The mold was then cooled to room temperature to obtain the desired product. Alloy particles / Cu composite material, as shown in the attached document Figure 4 As shown, the coefficient of thermal expansion of this composite material is .

[0052] 3. Preparation of solder strips

[0053] The Cu-based composite material was rolled to obtain a rectangular weld strip, and a 6 μm SnPb layer was deposited on the surface to achieve good weldability. (See attached image) Figure 5 As shown, the component defect rate dropped to 33.6%.

[0054] Example 2:

[0055] 1. Preparation of alloy particles:

[0056] (1) Weigh Mn, Co, Ge and Si elements (all with a purity greater than 99.9%) according to the molar mass ratio, and prepare by vacuum arc melting. To ensure uniform composition, the alloy ingot was vacuum annealed at 850℃ for 5 days. The negative thermal expansion curve of the alloy composition is shown in the attached figure. Figure 1 As shown;

[0057] (2) The alloy blocks, after mechanical crushing of the alloy ingot, are placed in a planetary ball mill and milled for 2 hours at a ball-to-material ratio of 8:1 and a rotation speed of 95 r / min to obtain... The size distribution range of the alloy particles is shown in the attached figure. Figure 2 As shown.

[0058] 2. Preparation of alloy particle / Cu-based composite materials:

[0059] (1) Mix six kinds of ingredients in equal weight ratios Alloy particles according to The weight ratio of the powder to pure Cu alloy powder is mixed in a ball mill, and the mixture is ball-milled for 1 hour at a ball-to-powder ratio of 9:1 and a rotation speed of 90 r / min to ensure that the alloy components are uniformly mixed.

[0060] (2) Mix Alloy particles / Cu powder were loaded into a mold and placed in a vacuum hot press furnace. A vacuum was drawn, and the mixture was vacuum-pressed at 900℃ and 3GPa for 8 minutes. The mold was then cooled to room temperature to obtain the desired product. Alloy particles / Cu composite material, as shown in the attached document Figure 4 As shown, the coefficient of thermal expansion of this composite material is .

[0061] 3. Preparation of solder strips

[0062] The Cu-based composite material was rolled to obtain a rectangular weld strip, and a 6 μm SnPb layer was deposited on the surface to achieve good weldability. (See attached image) Figure 5 As shown, the component defect rate decreased to 25.9%.

[0063] Example 3:

[0064] 2. Preparation of alloy particles:

[0065] (1) Weigh Mn, Co, Ge and Si elements (all with a purity greater than 99.9%) according to the molar mass ratio, and prepare by vacuum arc melting. To ensure uniform composition, the alloy ingot was vacuum annealed at 850℃ for 5 days. The negative thermal expansion curve of the alloy composition is shown in the attached figure. Figure 1 As shown;

[0066] (2) The alloy blocks, after mechanical crushing of the alloy ingot, are placed in a planetary ball mill and milled for 2 hours at a ball-to-material ratio of 8:1 and a rotation speed of 95 r / min to obtain... The size distribution range of the alloy particles is shown in the attached figure. Figure 2 As shown.

[0067] 2. Preparation of alloy particle / Cu-based composite materials:

[0068] (1) Mix six kinds of ingredients in equal weight ratios Alloy particles according to The weight ratio of the powder to pure Cu alloy powder is mixed in a ball mill, and the mixture is ball-milled for 1 hour at a ball-to-powder ratio of 9:1 and a rotation speed of 90 r / min to ensure that the alloy components are uniformly mixed.

[0069] (2) Mix Alloy particles / Cu powder were loaded into a mold and placed in a vacuum hot press furnace. A vacuum was drawn, and the mixture was vacuum-pressed at 900℃ and 3GPa for 8 minutes. The mold was then cooled to room temperature to obtain the desired product. Alloy particles / Cu-based composite materials, as shown in the attached document Figure 4 As shown, the coefficient of thermal expansion of this composite material is .

[0070] 3. Preparation of solder strips

[0071] The Cu-based composite material was rolled to obtain a rectangular weld strip, and a 6 μm SnPb layer was deposited on the surface to achieve good weldability. (See attached image) Figure 5 As shown, the component defect rate dropped to 13.3%.

[0072] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0073] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. An alloy material, characterized by comprising: The alloy material comprises the following raw materials: a metal; and, negative thermal expansion alloy particles, .

2. The alloy material of claim 1, wherein In the alloy material, the negative thermal expansion alloy particles account for 0.5wt%-1.5wt%, and the metal is copper.

3. A solder strip, characterized by The alloy material comprises: the alloy material according to claim 1 or 2, and a metal plating layer.

4. The solder strip of claim 3, wherein, The metal plating layer comprises at least one of tin, lead and bismuth.

5. A method of producing an alloy material, characterized by, The alloy material comprises the following steps: Mn, Co, Ge and Si were prepared by vacuum arc melting alloy ingot, x = 0.07-0.20; crushing and grinding the alloy ingot to obtain alloy particles; mixing the metal particles with metal powder and obtaining the alloy material through vacuum hot pressing.

6. The method of claim 5, wherein the alloy material is prepared by a method comprising: After the alloy ingot is prepared, annealing is performed at 850 degrees Celsius.

7. The method of claim 5, wherein the alloy material is prepared by a method comprising: Six portions of x of the negative thermal expansion alloy particles were taken as 0.07, 0.09, 0.11, 0.14, 0.17, 0.20, respectively, before the alloy ingot was broken and ground to obtain alloy particles Isodense mixing.

8. The method of claim 5, wherein the alloy material is prepared by a method comprising: The vacuum hot pressing is performed under the condition of 900±5 degrees Celsius, 3±0.5 GPa, and for 5-15 minutes.

9. A method of manufacturing a solder strip, characterized by The alloy material comprises the following steps: the steps of the method for preparing the alloy material according to claim 5, claim 6, claim 7 or claim 8; after the alloy material is processed into a shape, a metal layer is plated on the outer layer to obtain the solder strip.

10. A photovoltaic module, characterized by The alloy material comprises: the alloy material according to claim 1 or 2, the solder strip according to claim 3 or 4, the alloy material prepared by the method according to any one of claims 5-8, or the solder strip prepared by the method according to claim 9.

Images