{"id":5422,"date":"2023-03-20T16:10:53","date_gmt":"2023-03-20T08:10:53","guid":{"rendered":"https:\/\/www.ray-tron.com\/?p=5422"},"modified":"2023-09-01T13:39:37","modified_gmt":"2023-09-01T05:39:37","slug":"ele5487","status":"publish","type":"post","link":"https:\/\/www.ray-tron.com\/en\/ele5487\/","title":{"rendered":"What is photovoltaic tin-coated solder ribbon?"},"content":{"rendered":"

Tinned copper strips are generally used for crystalline siliconSolar Cells<\/a>The copper strips are divided into interconnection strips and busbars according to their functions, which are collectively called tinned welding strips. Interconnection strips are mainly used for the connection between single cells, and busbars are mainly used for the interconnection between battery strings and the connection of the internal circuits of the junction box. The welding rod is generally based on copper with a purity of 99.9% or above, and a layer of SnPb alloy of 10~25\u03bcm is plated on the surface to ensure good welding performance.<\/p>

According to the different copper substrates, the soldering strips can be divided into pure copper (99.9%) and oxygen-free copper (99.95%) soldering strips; according to the different coatings, they can be divided into tin-lead soldering strips (60%Sn, 40%Pb), lead-containing silver-tin coated soldering strips (62%Sn, 36%Pb, 2%Ag), lead-free and environmentally friendly tin coated soldering strips (96.5%Sn, 3.5%Ag), pure tin soldering strips, etc.; according to the yield strength, they can be divided into ordinary type, soft type, super soft type, etc.<\/p>

Since the output current of crystalline silicon solar cells is relatively large, the conductivity of the solder strip has a great influence on the output power of the component, so mostPhotovoltaic welding ribbon<\/a>Use oxygen-free copper above 99.95% to achieve the minimum resistivity and reduce the series resistance. Cause power loss. The soldering strip also needs to have excellent welding performance. During the welding process, it is necessary not only to ensure reliable welding without cold welding or over-welding, but also to minimize the warping and damage of the battery. Therefore, Sn60Pb40 alloy with a lower melting point is generally used as a coating. If a silver-containing coating is used, the melting point of the soldering strip will be reduced by 5\u00b0C, which is more conducive to improving welding performance, but it is usually not used due to its high cost. Reducing the yield strength of the soldering strip can improve the reliability of component welding and connection, especially stress release in thermal cycles, but this puts higher requirements on the manufacturing process of the soldering strip. The strength is controlled below 75MPa. The yield strength of the early soldering strip was too high, resulting in too low tensile strength and elongation. In actual use, there are many component failures caused by soldering strip problems.<\/p>

The width and thickness of the ribbon are selected according to the component design, or customized according to specific needs. Usually, the width of the interconnection ribbon is mainly determined by the width of the battery busbar, ranging from 1.5 to 0.9mm. For example, a 3-busbar battery generally uses a 1.5mm wide ribbon, and a 5-busbar battery uses a 0.9mm wide ribbon. The thickness of the substrate is generally 0.1~0.2mm, and the thickness of the coating is 0.025mm. The busbar is determined according to the current load requirements of the component. The thickness of the substrate is generally 0.1~0.25mm and the width is 4~8mm. At present, the development of multi-busbar components has brought new challenges to the processing of the welding ribbon, because multi-busbars require the use of round welding ribbons, which generally require a diameter of 0.3~0.5mm.<\/p>

\"\"