A brief description of solder and flux for soldering irons
Solder is a kind of fusible metal, which enables component leads to be connected to the connection points of printed circuit boards. Tin (Sn) is a soft, malleable silver-white metal, melting point of 232 ° C, at room temperature chemical stability, not easy to oxidise, no loss of metallic luster, resistance to atmospheric corrosion. Lead (Pb) is a softer light greenish-white metal, melting point of 327 ° C, high purity lead resistance to atmospheric corrosion, chemical stability, but harmful to humans. Tin in a certain proportion of lead and a small amount of other metals can be made into a low melting point, good mobility, strong adhesion to the components and wires, high mechanical strength, good electrical conductivity, not easy to oxidise, corrosion resistance, good, bright and beautiful solder joints solder, generally known as solder. Solder according to the amount of tin can be divided into 15 kinds, according to the amount of tin and impurities in the chemical composition is divided into S, A, B three grades. Manual welding commonly used wire solder.
V. Flux
① flux flux can generally be divided into inorganic flux, organic flux and resin flux, can dissolve the oxides on the surface of the metal to go, and in the welding and heating of the surface of the metal surrounded by the air to isolate, to prevent oxidation of the metal when heated; can reduce the surface tension of molten solder, conducive to the wetting of the solder.
② soldermask to limit the solder only in the need for soldering joints, the printed circuit board does not need to be welded to the board part of the cover, to protect the panel so that it is welded by the thermal shock is small, is not easy to blister, but also play a role in preventing bridging, pulling the tip, short-circuiting, false soldering and so on. The use of flux, must be welded according to the size of the area and the surface of the state of the appropriate amount of application, the dosage is too small to affect the quality of welding, the dosage is too much, the flux residue will corrode the components or make the circuit board insulation performance deterioration.
