Low-temperature alloy solder, low-temperature alloy solder strip and welding method

Abstract

The invention belongs to the technical field of solar cells, and particularly relates to a low-temperature alloy solder, a low-temperature alloy solder strip and a welding method. The invention provides a low-temperature alloy solder which comprises the following components in percentage by mass: 30-40% of tin, 30-50% of bismuth, 1-2% of silver, 0.1-0.5% of copper, 5-10% of nickel and 4-9% of zinc. According to the low-temperature alloy solder provided by the invention, reliable welding can be realized at low temperature, and the welding cost can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to a low-temperature alloy solder, a low-temperature alloy solder strip and a welding method. Background Art

[0002] In order to improve the photoelectric conversion efficiency and reduce the manufacturing cost, silicon wafer thinning has become one of the current trends in the development of solar cell technology. The thickness of silicon wafers in emerging solar technologies such as TOPcon, HJT, and IBC has been reduced to less than 200μm. However, silicon wafer thinning greatly increases the risk of silicon wafers cracking under thermal stress during the manufacturing process of solar cells, and low-temperature manufacturing process has become one of the necessary conditions for the manufacturing of thinned silicon wafer cells. Cell string welding is one of the links in the production process of solar cells with a high probability of thermal damage to cells. Reducing the welding temperature has become an effective means to improve the problem of cell cracking. The cell welding temperature is directly determined by the melting point of the solder used in the photovoltaic ribbon. The melting point of Sn60Pb40 and Sn63Pb37 solders commonly used in photovoltaic ribbons is about 183℃~185℃. The corresponding welding temperature needs to reach about 230℃ to achieve reliable welding, but the current thinned cells have a very high risk of cracking when welded at this temperature.

[0003] Therefore, in order to further reduce the welding temperature of the cell and adapt to the trend of thinning of solar cells, it is necessary to develop photovoltaic welding ribbons with lower welding temperatures. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, an embodiment of the present invention provides a low-temperature alloy solder that can achieve reliable welding at low temperatures and can effectively reduce welding costs.

[0005] The low-temperature alloy solder of the embodiment of the present invention includes: 30-40% tin, 30-50% bismuth, 1-2% silver, 0.1-0.5% copper, 5-10% nickel, and 4-9% zinc, calculated in percentage by mass.

[0006] The advantages and technical effects brought by the warm alloy solder of the embodiment of the present invention can realize reliable welding at low temperature and can effectively reduce welding costs.

[0007] In some embodiments, the low temperature alloy solder includes: 34-39% tin, 35-48% bismuth, 1.5-2% silver, 0.1-0.3% copper, 6-9% nickel, and 5-8% zinc, calculated in percentage by mass.

[0008] In some embodiments, the low temperature alloy solder includes: 37-38% tin, 40-45% bismuth, 1.5-1.8% silver, 0.2-0.3% copper, 7-9% nickel, and 5-7% zinc, calculated in percentage by mass.

[0009] In some embodiments, the low temperature alloy solder includes: 37% tin, 45% bismuth, 1.7% silver, 0.3% copper, 9% nickel, and 7% zinc, calculated in percentage by mass.

[0010] In some embodiments, the melting point of the low temperature alloy solder is T1, and T1≤200°C.

[0011] An embodiment of the present invention further provides a low-temperature alloy solder strip, comprising the above-mentioned low-temperature alloy solder.

[0012] In some embodiments, the low-temperature alloy solder strip includes a conductive base strip and a solder layer coated on the surface of the conductive base strip, and the solder layer is composed of a low-temperature alloy solder.

[0013] In some embodiments, the conductive base strip is made of copper, copper-aluminum alloy, copper-silver alloy or copper-silver-aluminum alloy.

[0014] In some embodiments, the thickness of the low temperature alloy welding strip is 0.2 mm to 0.8 mm.

[0015] The embodiment of the present invention further provides a method for welding a low-temperature alloy welding strip, which welds the low-temperature alloy welding strip and the ITO film of the photovoltaic cell together by low-temperature ultrasonic welding. DETAILED DESCRIPTION

[0016] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0017] The low-temperature alloy solder of the embodiment of the present invention includes: 30-40% tin, 30-50% bismuth, 1-2% silver, 0.1-0.5% copper, 5-10% nickel, and 4-9% zinc, calculated in percentage by mass.

[0018] The warm alloy solder of the embodiment of the present invention can realize reliable welding at low temperature and can effectively reduce welding costs.

[0019] In some embodiments, preferably, the low temperature alloy solder comprises: 34-39% tin, 35-48% bismuth, 1.5-2% silver, 0.1-0.3% copper, 6-9% nickel, 5-8% zinc, in terms of mass percentage. Further preferably, the low temperature alloy solder comprises: 37-38% tin, 40-45% bismuth, 1.5-1.8% silver, 0.2-0.3% copper, 7-9% nickel, 5-7% zinc, in terms of mass percentage. Even more preferably, the low temperature alloy solder comprises: 37% tin, 45% bismuth, 1.7% silver, 0.3% copper, 9% nickel, 7% zinc, in terms of mass percentage.

[0020] In some embodiments, preferably, the melting point of the low temperature alloy solder is T1, and T1≤200°C.

[0021] An embodiment of the present invention further provides a low-temperature alloy solder strip, comprising the above-mentioned low-temperature alloy solder.

[0022] In some embodiments, preferably, the low temperature alloy solder strip comprises a conductive base strip and a solder layer coated on the surface of the conductive base strip, and the solder layer is composed of a low temperature alloy solder. Further preferably, the conductive base strip is made of copper, copper-aluminum alloy, copper-silver alloy or copper-silver-aluminum alloy.

[0023] In some embodiments, preferably, the thickness of the low-temperature alloy welding strip is 0.2 mm to 0.8 mm, for example, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, etc.

[0024] The embodiment of the present invention further provides a method for welding a low-temperature alloy welding strip, which welds the low-temperature alloy welding strip and the ITO film of the photovoltaic cell together by low-temperature ultrasonic welding.

[0025] The technical solution of the present invention is described in detail below in conjunction with specific embodiments.

[0026] Example 1

[0027] (1) Weigh raw materials with a purity of 99.99%: 35wt% tin powder, 1.8wt% silver powder, 49wt% bismuth powder, 0.2wt% copper powder, 6wt% nickel powder, and 8wt% zinc powder; place the weighed raw materials in a vacuum melting furnace for vacuum heating and melting, and introduce nitrogen or argon atmosphere protection; the vacuum degree of the vacuum melting furnace is 6×10 -4 Pa, the temperature is 1800℃, and the melting time is 2h; low temperature alloy solder is obtained;

[0028] (2) heating the prepared low-temperature alloy to a molten state, and then forming a dense solder layer on the surface of the base strip to obtain a low-temperature alloy solder strip with a thickness of 0.3 mm; wherein the conductive base strip is made of a copper-aluminum alloy;

[0029] (3) The prepared low-temperature alloy welding strip is welded to the ITO film of the HJT battery by low-temperature ultrasonic welding; the ultrasonic welding power is 10KHz, the ultrasonic welding time is 300s, and the ultrasonic welding temperature is 150°C.

[0030] The photovoltaic welding strip prepared in Example 1 can be low-temperature welded with the ITO film of the HJT battery. The welding temperature can be as low as 150° C., and the welding strength can reach 1.1 MPa.

[0031] Example 2

[0032] (1) Weigh raw materials with a purity of 99.99%: 31wt% tin powder, 1.7wt% silver powder, 50wt% bismuth powder, 0.3wt% copper powder, 9wt% nickel powder, and 8wt% zinc powder; place the weighed raw materials in a vacuum melting furnace for vacuum heating and melting, and introduce nitrogen or argon atmosphere protection; the vacuum degree of the vacuum melting furnace is 6×10 -4 Pa, the temperature is 1800℃, and the melting time is 2h; low temperature alloy solder is obtained;

[0033] (2) heating the prepared low-temperature alloy to a molten state, and then forming a dense solder layer on the surface of the base strip to obtain a low-temperature alloy solder strip with a thickness of 0.4 mm; wherein the conductive base strip is made of a copper-aluminum alloy;

[0034] (3) The prepared low-temperature alloy welding strip is welded to the ITO film of the HJT battery by low-temperature ultrasonic welding; the ultrasonic welding power is 10KHz, the ultrasonic welding time is 300s, and the ultrasonic welding temperature is 150°C.

[0035] The photovoltaic welding strip prepared in Example 2 can be low-temperature welded with the ITO film of the HJT battery. The welding temperature can be as low as 150° C., and the welding strength can reach 1.0 MPa.

[0036] Example 3

[0037] (1) Weigh raw materials with a purity of 99.99%: 37wt% tin powder, 1.7wt% silver powder, 45wt% bismuth powder, 0.3wt% copper powder, 9wt% nickel powder, and 7wt% zinc powder; place the weighed raw materials in a vacuum melting furnace for vacuum heating and melting, and introduce nitrogen or argon atmosphere protection; the vacuum degree of the vacuum melting furnace is 6×10 -4 Pa, the temperature is 1800℃, and the melting time is 2h; low temperature alloy solder is obtained;

[0038] (2) heating the prepared low-temperature alloy to a molten state, and then forming a dense solder layer on the surface of the base strip to obtain a low-temperature alloy solder strip with a thickness of 0.6 mm; wherein the conductive base strip is made of a copper-aluminum alloy;

[0039] (3) The prepared low-temperature alloy welding strip is welded to the ITO film of the HJT battery by low-temperature ultrasonic welding; the ultrasonic welding power is 10KHz, the ultrasonic welding time is 300s, and the ultrasonic welding temperature is 150°C.

[0040] The photovoltaic welding strip prepared in Example 3 can be low-temperature welded with the ITO film of the HJT battery. The welding temperature can be as low as 150° C., and the welding strength can reach 1.3 MPa.

[0041] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0042] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A low temperature alloy solder, characterized in that: include: Tin 30-40%, bismuth 30-50%, silver 1-2%, copper 0.1-0.5%, nickel 5-10%, zinc 4-9%, calculated in percentage by mass.

2. The low temperature alloy solder according to claim 1, characterized in that: include: Tin 34-39%, bismuth 35-48%, silver 1.5-2%, copper 0.1-0.3%, nickel 6-9%, zinc 5-8%, calculated in percentage by mass.

3. The low temperature alloy solder according to claim 1, characterized in that: include: Tin 37-38%, bismuth 40-45%, silver 1.5-1.8%, copper 0.2-0.3%, nickel 7-9%, zinc 5-7%, calculated in percentage by mass.

4. The low temperature alloy solder according to claim 1, characterized in that: include: Tin 37%, bismuth 45%, silver 1.7%, copper 0.3%, nickel 9%, zinc 7%, calculated in percentage by mass.

5. The low temperature alloy solder according to any one of claims 1 to 4, characterized in that: The melting point of the low temperature alloy solder is T1, and T1 is ≤ 200°C.

6. A low temperature alloy welding strip, characterized in that: The invention comprises the low temperature alloy solder as claimed in any one of claims 1 to 5.

7. The low temperature alloy welding strip according to claim 6, characterized in that: The invention comprises a conductive base strip and a solder layer coated on the surface of the conductive base strip, wherein the solder layer is composed of low-temperature alloy solder.

8. The low temperature alloy welding strip according to claim 7, characterized in that: The conductive base strip is made of copper, copper-aluminum alloy, copper-silver alloy or copper-silver-aluminum alloy.

9. The low temperature alloy welding strip according to any one of claims 6 to 8, characterized in that: The thickness of the low-temperature alloy welding strip is 0.2 mm to 0.8 mm.

10. The welding method of low temperature alloy welding strip according to any one of claims 6 to 9, characterized in that: The low-temperature alloy welding strip is welded together with the ITO film of the photovoltaic cell by low-temperature ultrasonic welding.