CN103022203A - Photovoltaic solder strip and preparation method thereof - Google Patents

Abstract

The invention relates to a novel photovoltaic solder strip which is low in cost and efficient. The main structure of the photovoltaic solder strip uses an aluminum core as a conducting material, and a layer of welding alloy is respectively covered on the upper surface and the lower surface to be used as a welding material. The production cost of the solder strip is 15%-20% lower than that of a convention solder strip, the performance of the solder strip is similar to that of the convention solder strip, and the photovoltaic solder strip can be used for preparing solar cell modules.

Description

A kind of photovoltaic ribbon and preparation method thereof

Technical Field The present invention belongs to the field of solar cells, and relates to a new low-cost, high-efficiency photovoltaic ribbon.

Background technique

At present, the conventional photovoltaic ribbons use copper core as the conductive material, and then cover the surface of the copper core with a layer of tin-lead soldering material as the soldering layer; finally process it into the required size specification.

With the development of the industry, the control of the cost of materials is becoming more and more strict. Although the copper core has good electrical conductivity, the price remains high because copper is a precious metal material. In recent years, with the fluctuation of the international non-ferrous metal futures market, the price of copper materials has also risen.

The corrosion resistance of copper is poor, and the solar cell module will release some organic corrosion components under long-term outdoor working conditions. These corrosion components can directly react with the copper core to affect its conductivity and reliability.

Although the conductivity of aluminum is slightly worse than that of copper, the cost is much lower than that of copper. Even under the same electrical conductivity conditions, the cost of aluminum is less than 50% of the cost of copper.

Aluminum cannot be directly welded to the silver grid wires on the solar cells, and a layer of welding material needs to be covered on the surface. Due to the nature of the aluminum itself, how to cover it with a layer of welding material at low cost has not been well resolved.

Contents of the invention

In order to solve the shortcomings of existing photovoltaic ribbons, the present invention uses aluminum cores as conductive materials, and covers the upper and lower surfaces of the aluminum cores with a layer of welding material as a soldering layer, thereby providing a solution to replace existing conventional soldering ribbons. Technical scheme of the present invention is:

A photovoltaic welding ribbon, comprising a conductive material, the conductive material is an aluminum core base material with a purity higher than 99.9%, and welding alloy layers are arranged on the upper and lower surfaces of the aluminum core base material.

The thickness of the aluminum core base material is 0.1mm~1mm, and the width can be adjusted according to the battery sheet to be welded. The conventional width size is 1mm, 1.5mm, 2mm, etc.

The upper and lower surfaces of the aluminum core substrate are covered with a layer of weldable alloy, the thickness of the weldable alloy layer is 0.005mm to 0.05mm, and its material composition can be adjusted according to different applications. For example, the welding alloy required for conventional photovoltaic welding is tin-lead alloy, the typical mass percentage is Sn63Pb37, or Sn60Pb40; in order to increase the conductivity and welding performance of the alloy layer, the alloy mass composition can be adjusted to Sn62Pb36Ag2; in some lead-free applications, The alloy can be Sn-Ag system, Sn-Cu system, Sn-Bi system, Sn-In system and Sn-Zn system, typical mass percentages are Sn42Bi58, Sn85Bi10Zn5, Sn52In20Ag28 and so on. The process of covering the conductive material of the aluminum core with the welding material can be electroless plating, electroplating, or hot-dip plating.

There may be a transition alloy layer between the conductive material of the aluminum core and the welding alloy layer to improve the bonding force between the two. The transition alloy layer can be a material that has a good bonding force with the aluminum core, such as a metal nickel layer, a metal zinc layer, etc., and the thickness Can be 0.0005mm to 0.005mm.

The present invention also provides a preparation method for the photovoltaic soldering strip, first surface-activating the aluminum core base material, and then covering the upper and lower surfaces of the aluminum core conductive material with the welding material by electroless plating, electroplating, or hot-dip plating .

Before covering the coating, it is necessary to activate the surface of the aluminum core substrate. The surface activation treatment can be ultrasonic activation treatment, plasma activation treatment, zinc precipitation activation treatment; the process of zinc precipitation activation treatment is chemical degreasing -Alkali etching-acid etching-primary zinc precipitation-nitric acid dezincification-secondary zinc precipitation; oil removal can be organic solvent (C2-H-Cl3) oil removal, alkali etching and acid etching are mainly to remove oxidation on the surface of the aluminum core layer, the alkali etching condition is to corrode in NaOH solution with a mass percentage of 10-30% for 0.5 minutes to _{5 minutes ;} Corrosion in ~30% NH ₄ F solution for 1 minute to 10 minutes; the main function of zinc precipitation is to further remove the surface oxide layer, and the time is about 1 second to 60 seconds. The conditions for nitric acid dezincification are 5-25% _HNO3 solution by mass percentage, and the time is 0.5-5 minutes.

The production cost of the welding strip of the present invention is 15%-20% lower than that of the conventional welding strip, and its performance is similar to that of the conventional welding strip. It can also reach 2.5μΩ·cm, which can be used in the preparation of solar cell modules.

Description of drawings

Figure 1 is a schematic diagram of a stack of photovoltaic modules.

Reference number

1 glass

2 EVA (1)

3 Solar cells connected in series

4 EVA (two)

5 Backplane.

Detailed ways

This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments.

Embodiment one

1. The aluminum core substrate with a purity higher than 99.9% is used as the conductive material. The thickness of the aluminum core substrate is 0.3mm and the width is 1.5mm.

2. The aluminum core substrate is subjected to zinc-precipitation activation treatment, and the process is as follows: 1) Degreasing with 40% C2-H-Cl3 organic solvent; 2) Corroding in 20% NaOH alkaline solution for 1 minute, Then corrode for 4 minutes in an acidic solution with a mass percentage of 50% H ₃ PO ₄ , 25% HNO ₃ and 25% NH ₄ F; alkali etching and acid etching are mainly to remove the oxide layer on the surface of the aluminum core; 3) Zinc precipitation treatment In order to further remove the surface oxide layer, the time is about 10 seconds; 4) Dezincification treatment with 10% nitric acid solution for 2 minutes; 5) Secondary zinc precipitation, the time is 20 seconds.

3. A metal nickel layer is electroplated on the surface of the aluminum layer with a thickness of 0.0005 mm.

4. Dip the electroplated material in a 300°C lead-containing tin pool (the mass ratio of tin to lead is 3:2) for 3 seconds, and hot-dip a layer of Sn60Pb40 with a thickness of 0.02mm on the surface of the solder strip.

Embodiment two

1. The aluminum core substrate with a purity higher than 99.9% is used as the conductive material, the thickness of the aluminum core substrate is 0.1mm, and the width is 1mm.

2. The aluminum core substrate is subjected to zinc-precipitation activation treatment. The process is: 1) Degreasing with 35% C2-H-Cl3 organic solvent; 2) Corroding in 15% NaOH alkaline solution for 1 minute, Then corrode for 3 minutes in an acidic solution with a mass percentage of 45% H ₃ PO ₄ , 30% HNO ₃ and 30% NH ₄ F; alkali etching and acid etching are mainly to remove the oxide layer on the surface of the aluminum core; 3) Zinc precipitation treatment In order to further remove the surface oxide layer, the time is about 10 seconds; 4) Dezincification treatment with 5% nitric acid solution for 5 minutes; 5) Secondary zinc precipitation, the time is 20 seconds.

3. A metal zinc layer is electroplated on the surface of the aluminum layer with a thickness of 0.005mm.

4. Dip the electroplated material in a bismuth-containing tin pool (the mass ratio of tin to bismuth is 7:10) at 200°C for 2.5 seconds, and hot-dip a layer of Sn42Bi58 with a thickness of 0.02mm on the surface of the solder strip.

Embodiment three

1. The aluminum core substrate with a purity higher than 99.9% is used as the conductive material. The thickness of the aluminum core substrate is 1mm and the width is 2mm.

2. The aluminum core substrate is subjected to zinc-precipitation activation treatment, and the process is as follows: 1) Degreasing with 35% C2-H-Cl3 organic solvent; 2) Corroding in 30% NaOH alkaline solution for 0.5 minutes, Then corrode for 5 minutes in an acidic solution with a mass percentage of 70% H ₃ PO ₄ , 10% HNO ₃ and 10% NH ₄ F; alkali etching and acid etching are mainly to remove the oxide layer on the surface of the aluminum core; 3) Zinc precipitation treatment In order to further remove the surface oxide layer, the time is about 20 seconds; 4) Dezincification treatment with 25% nitric acid solution for 0.5 minutes; 5) Secondary zinc precipitation, the time is 20 seconds.

3. A metal nickel layer is electroplated on the surface of the aluminum layer with a thickness of 0.0005 mm.

4. Dip the electroplated material in a tin pool containing indium and silver (the mass ratio of tin, indium and silver is 13:5:7) at 400°C for 3 seconds, and hot-dip a layer of 0.015 mm thickness of Sn52In20Ag28.

Embodiment Four

The accompanying drawings described here are used to further explain the present invention and constitute a part of the application. The schematic diagrams of the present invention are used to explain the present invention and do not constitute improper limitations to the present invention. The protection scope of the present invention is not limited to the following The schematic diagram.

1. After the battery has passed the electrical performance test, the aluminum welding strips are respectively welded to the front and back electrodes of the battery sheet.

2. Connect the welded monolithic batteries in series.

3. As shown in Figure 1: Prepare glass 1, upper layer EVA 2, solar cells 3 after string welding, lower layer EVA 4, and back plate 5. Lay a layer of 0.5mm thick transparent EVA2 on the glass 1, then lay the string-welded battery 3, and then connect the string-welded solar cells by welding. Then lay EVA 4 on the back side of this solar cell 3, and finally lay the back plate

5. Put the laminated materials into the laminator for lamination. After the lamination, cut the excess EVA and the back plate at the edge, and carry out the subsequent process after the laminate is cooled.

Claims (7)

1. A photovoltaic ribbon, comprising a conductive material, characterized in that: the conductive material is an aluminum core base material with a purity higher than 99.9%, and a welding alloy layer is arranged on the upper and lower surfaces of the aluminum core base material. 2 . The photovoltaic ribbon according to claim 1 , wherein the thickness of the aluminum core base material is 0.1 mm to 1 mm; the thickness of the welding alloy layer is 0.005 mm to 0.05 mm. 3. The photovoltaic ribbon according to claim 1, characterized in that there is a transition alloy layer between the aluminum core conductive material and the solder alloy layer. 4. The photovoltaic ribbon according to claim 4, wherein the transition alloy layer is a metal nickel layer or a metal zinc layer with a thickness of 0.0005 mm to 0.005 mm. 5. A preparation method for photovoltaic welding ribbon according to claim 1, characterized in that, the aluminum core base material is first subjected to surface activation treatment, and then the welding material is covered on the aluminum core by chemical plating, electroplating or hot-dip plating. The upper and lower surfaces of the core conductive material. 6 . The preparation method according to claim 5 , wherein the surface activation treatment of the aluminum core base material is ultrasonic activation treatment, plasma activation treatment, or zinc precipitation activation treatment. 7. The preparation method according to claim 5, characterized in that: the process of zinc precipitation activation treatment is chemical degreasing-alkali etching-acid etching-primary zinc precipitation-nitric acid dezincification-second zinc precipitation.

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