Vacuum brazing

    Vacuum brazing is to heat the solder to the melting point in a vacuum state, and the molten liquid metal solder fills the gap of the metal to be soldered (referred to as the base metal) to weld the base metal together. It has the advantages of low welding temperature, small deformation, small changes in the properties of the base metal, and can simultaneously complete the welding of multiple parts and the welding of different materials with very different properties. It is especially suitable for the welding of small components with complex structures.

    According to the heating method, vacuum brazing can be divided into radiation furnace brazing, high frequency brazing, high current brazing, resistance brazing and so on. According to the melting point and strength of the solder, vacuum brazing can be divided into two types: brazing and soldering. Solder whose melting point is above 500°C is called brazing, and the strength of welded joints is higher, and brazing whose melting point is below 500°C is called soldering, and its joint strength is lower.

    The solder composition used for vacuum brazing must not contain metal elements with high vapor pressure, such as mercury, sulfur, cesium, lead, zinc, cadmium, potassium, selenium, sodium, phosphorus, magnesium, strontium, antimony, bismuth, arsenic, Calcium etc. The content of a single impurity element in the solder should be less than 0.002%, and the total content of impurities should be less than 0.05%. The air content is not allowed to exceed 0.001%, and organic and inorganic non-metallic impurities are not allowed to be mixed, otherwise the (boiling) tiny bubbles generated by the molten solder during vacuum brazing will cause the weld to form pores.

(Huiputech)