Introducing the difference between soldering iron wattages
In the electrical repair process, the soldering iron is an indispensable tool, but a lot of just contact with the soldering iron maintenance personnel, do not know the welding process according to what criteria to choose the power of the soldering iron, often a soldering iron to go all over the world. The most direct consequence is due to not pay attention to the choice of the power size of the soldering iron, resulting in unsatisfactory welding results.
The use of soldering iron power is too large, easy to burn components (generally diode, triode junction temperature of more than 200 ℃ will be burned) and make the printed wire from the substrate off; the use of soldering iron power is too small, solder can not be fully melted, flux can not be volatilised out of the soldering point is not smooth, not firm, easy to produce virtual welding. Generally, used for welding integrated circuits, printed circuit boards, CMOS circuits, decorative transistors, IC-type tape recorders, televisions, for ordinary circuit experiments, generally 20W is appropriate, repair vacuum tube machines, such as gall bladder, old instruments, to 35W is appropriate, the external heat type is 45W, welding large transformer wiring, grounding trunks on the metal substrate, it is the use of the internal heat type 50W, external heat type 75W. If you want to weld metal materials, you should choose more than 100W external hot soldering iron. If the conditions allow, amateur radio enthusiasts can be equipped with a 2OW endothermic, a 35W endothermic or exothermic, a 150W exothermic soldering iron, which basically meets the needs of a variety of welding.
We use the solder is generally divided into leaded and lead-free solder two kinds of solder, but the most commonly used is leaded solder, composition is 63% tin, lead 37%, melting point 183 ℃: and lead-free solder composition is 99% tin, flux for about 1%, melting point 227 ℃. Leaded solder has the advantage of low melting point, easy to weld, low price, but not environmentally friendly, lead is harmful to the human body, so after the completion of welding, be sure to wash your hands carefully, in the welding process, it is best to wear a mask, or brightly lit places, to ensure that the head and the weldment a certain distance. With the enhancement of people's awareness of environmental protection, now the machine welding in factories are using lead-free solder. Since the melting point of lead-free solder is higher, it is easy to understand why it is sometimes harder to melt the solder when repairing imported electrical appliances.
A soldering iron is an electric heating device that produces a high temperature of about 250°C when energised. Soldering iron in the welding process, is actually a heat conduction process, in contact with the welding surface, the soldering iron head on the heat transfer to the solder, the solder absorbs the heat melting flow and under the action of surface tension, the formation of a bright rounded solder joint. In the welding heat conduction process, because the metal is a good conductor of heat, heat transfer faster. Solder melting process, due to the iron tip of the heat loss, its temperature are more or less down, if the soldering point area is larger, need to absorb more heat to make its above the solder to reach the melting point. If the soldering iron head volume is small, less heat storage, the temperature drops faster, due to the iron core power smaller heat generated to supplement the loss of heat, the most intuitive phenomenon at this time is the solder is not melted or melting is not complete. In this case, we have to choose high-power soldering iron for welding. On the contrary, if the welding piece is small, we do not need to choose a high-power soldering iron; if you use a high-power soldering iron, be sure to pay attention to the welding time, otherwise too much heat is easily caused by the current flow through the road called circuit, circuit board damage, resulting in the printing of copper foil off. Specifically how high power soldering iron is appropriate, there is no specific quantitative requirements, maintenance personnel of the long-term work experience is the best way to choose the best way to suit their own soldering iron.
