First, electric soldering iron
The main tool for manual welding is the electric soldering iron. There are many kinds of electric iron, direct heat type, induction type, energy storage type and temperature control type, electric power is 15W, 2OW, 35w...... 300W variety, mainly according to the size of the weldment to decide. General components of the welding to 2OW internal hot electric soldering iron is appropriate; Energy storage electric soldering iron can be used when welding integrated circuits and vulnerable components; Large welding parts can be used 150W~300W high power external heat type electric soldering iron. Small power electric soldering iron head temperature is generally between 300~400℃.
Soldering iron head is generally made of red copper material. In order to protect the iron head from oxidation and rust under high temperature conditions of welding, the iron head is often treated by electroplating. Some iron heads are also made of alloy materials that are not easy to oxidize. The new iron head should be tinned before formal welding. The method is to polish the iron head with gauze paper, and then dip into the rosin, dip in the solder on the hard object (such as wood) repeatedly grinding, so that each face of the iron head all tin.
If the use of a long time, the iron head has been oxidized, to use a small file to gently file the surface oxidation layer, after exposing the bright copper with the same method as the new iron head tin plating for processing. When only a electric iron is used, the temperature of the iron head can be adjusted by using different methods to insert the iron core into the iron head. The longer the iron head is pulled out from the iron core, the lower the temperature of the iron head is relatively, and the higher the temperature is on the contrary. It can also be used to change the size and shape of the iron head to adjust the temperature of the iron head. The thinner the iron head, the higher the temperature; The thicker the iron head, the lower the relative temperature.
According to the type of welding components can choose the appropriate shape of the iron head. The shape of the iron head is conical, inclined oval and chisel and so on. Conical welding can be used for small solder joints, and chisel or cylindrical welding can be used for large solder joints.
There is also a tin absorbing electric iron, which is composed of a tin absorbing mechanism increased on the direct heat type electric iron. This kind of electric iron is used when dissoldering components in the circuit
Two, solder and flux
Solder is the main material for welding. Solder for welding electronic components is actually a kind of tin lead alloy, different tin lead ratio solder melting point temperature is different, generally 180~230 ℃. Manual welding is suitable for the use of tubular solder wire, solder wire sandwiched with rosin and activator, extremely convenient to use. Tubular solder wire has 0.5, 0.8, 1.0, 1.5... Such as a variety of specifications, can be conveniently selected.
Flux, also known as flux, is a kind of material that can clean and protect the surface of the welding metal after being heated. An oxide film is readily formed on the surface of the metal in the air. This oxide film prevents the solder from wetting the welding metal. The proper use of flux can remove the oxide film, so that the welding quality is perfect, the surface of the solder joint is smooth and rounded.
The purpose of PCB galvanizing is to prevent steel objects from being corroded, improve the corrosion resistance and service life of steel, but also make the product increase the decorative appearance, steel with the growth of time will be weathering, water or soil corrosion. Domestic annual corrosion of steel almost accounts for one tenth of the total amount of steel, so in order to protect the service life of steel or its parts, generally using PCB galvanizing to iron and steel processing.
Because zinc is not easy to change in dry air, and in the humid environment * can produce a basic zinc carbonate film, this film can protect the internal parts and not be damaged by corrosion, even if the zinc layer is damaged by some factors, zinc and steel after a period of time will form a microbattery, and the steel matrix as the cathode and protected.
Zinc is a metal with a bluish-white sheen. Atomic number 30, relative atomic mass 65.4, brittle and hard, melting point 419.4 ℃, boiling point 907℃, valence +2, relative density 7.1. Zinc is stable in dry air. Zinc is an amphoteric metal, acid, alkali will react to release hydrogen. It also reacts with hydrogen sulfide. A basic zinc carbonate film is formed in water or moist air to protect the underlying layer from corrosion.
Galvanized on iron, because of its negative potential, is anodic coating, has good electrochemical protection. Therefore, galvanizing (plus passivation with chromate after plating) is widely used to prevent the corrosion of ferrous metals. It is widely used in electroplating electrical parts, mechanical hardware, building hardware and industry.
Zinc is mainly used in industry for electroplating, hot dip plating, battery industry and manufacturing alloys (such as brass).