An aluminum soldering paste is characterized in that it contains the following components by weight: SnCl 250% to 80%, fluoride 3 to 10%, and organic solvent 15 to 40%. The fluoride is selected from one or a mixture of aluminum fluoride, zinc fluoride, and potassium fluoride. The organic solvent is an alcoholic organic solvent. The organic solvent is selected from one or a mixture of more of methanol, ethanol, and propanol. The aluminum brazing paste of the present invention is a reactive solder paste. The stannous chloride contained in the paste reacts with the aluminum metal in contact to generate tin metal, and activates the surface of the aluminum metal to form an alloy and complete the welding. It is suitable for aluminum brazing. No solder is required during use. You only need to apply solder paste to the aluminum parts to perform soldering, which facilitates the aluminum soldering operation.
Aluminum soldering paste, preparation method and use
Technical field
The present invention relates to a soldering paste, in particular to an aluminum soldering paste used for aluminum soldering and its preparation method and use.
Background technique
Brazing uses a metal with a lower melting point than the base metal as a filler metal. After heating, the filler metal melts but the weldment does not melt. The liquid filler metal is used to moisten the base metal, fill the joint gap and mutually diffuse with the base metal to secure the weldment. of connected together. According to the different melting points of solder, soldering is divided into soft soldering and hard soldering. The melting point of soldering solder is lower than 450℃, and the joint strength is low (less than 70MPa). Therefore, soldering is mostly used for welding conductive, airtight and watertight devices in the electronics and food industries, using tin-lead alloy as solder. Soldering is most commonly used. The melting point of brazing filler metal is higher than 450°C, and the joint strength is higher (greater than 200MPa).
Flux is a flux used during brazing. Its function is to remove oxides on the surface of the solder and base metal, protect the weldment and the liquid solder from oxidation during the brazing process, and improve the performance of the liquid solder on the weldment. Wettability. For most brazing processes, filler metal and flux need to be used at the same time, which brings certain inconvenience to the brazing operation.
In order to solve the problem of unchanged operation when soldering material and flux are used at the same time, solder paste appeared. Solder paste is a homogeneous mixture composed of alloy solder powder, paste flux and some additives. It is a paste with a certain viscosity and good thixotropy. The appearance of solder paste facilitates the operator's soldering of connectors. In the existing technology, solder paste is often used for soldering electronic components. At normal temperature, solder paste can initially stick electronic components to a predetermined position. When heated to a certain temperature, as the solvent and some additives evaporate, The melting of the alloy powder interconnects the components to be welded and the pads, and cools to form a permanently connected solder joint. Since welding of electronic components is usually done by soft soldering, the welding temperature is low, and the melting point of the solder is usually lower than 450°C. Therefore, the alloy solder powder of the solder paste in the prior art is also soft solder, and this solder paste is only suitable for Suitable for soft soldering, not suitable for aluminum brazing.
Contents of the invention
The present invention provides an aluminum brazing paste, which aims to solve the existing technical problems and provide an aluminum brazing paste suitable for aluminum brazing. The soldering paste combines flux and brazing material to facilitate aluminum brazing. operation.
The technical solution adopted by the present invention to solve the problem is:
An aluminum soldering paste contains the following components by weight: SnCl 250% to 80%, fluoride 3 to 10%, and organic solvent 15 to 40%.
The preferred content of each component is: SnCl260%-75%, fluoride 5-8%, and organic solvent 20-30%.
The fluoride is selected from one or a mixture of aluminum fluoride, zinc fluoride, potassium fluoride, and sodium fluoride.
The organic solvent is an alcoholic organic solvent.
The organic solvent is selected from one or a mixture of more of methanol, ethanol, and propanol.
The preparation method of the above-mentioned aluminum brazing paste includes the following steps: mix stannous chloride and the above-mentioned fluoride in proportion, add them to a ball mill, add an alcohol solvent, and perform ball milling and mixing for 2 to 4 hours.