A few differences between an internally heated soldering iron and an externally heated soldering iron
Endothermic soldering iron is smaller and cheaper. General electronic production are used 20W-30W internal heat type soldering iron. Of course, there is a 50W externally heated soldering iron can be prepared. Endothermic soldering iron heating efficiency is higher, and replace the iron head is also more convenient.
External heat type, as the name says, "external heat" means "heat outside", because the heat generating resistor is outside of the soldering iron and so named.
It is suitable for soldering both large components and small ones. Due to the heating resistor wire in the outside of the iron head, most of the heat is emitted to the external space, so the heating efficiency is low and the heating speed is slow. It generally takes 6 to 7 minutes to preheat before welding.
Its volume is large, welding small devices appear to be inconvenient. But it has the advantages of longer use of the soldering iron tip and higher power, with 25W, 30W, 50W, 75W, 100W, 150W, 300W and other specifications.
High-power soldering iron is usually external heat type. Soldering iron is used for soldering, in order to facilitate the use, usually made of "solder wire", solder wire generally contain flux rosin.
Soldering wire is synthesized using about 60% tin and 40% lead, and has a low melting point.
Rosin is a kind of flux, rosin can help soldering, people who play erhu must have it, I heard that you can also buy it at the drugstore. Rosin can be used directly, can also be configured into a rosin solution, that is, the rosin crushed, put into a vial, and then add the alcohol and stir. Note that the alcohol is volatile, remember to tighten the cap after use.
Bottle can be placed in a small piece of cotton, use tweezers to clip out when applied to the printed board or components. Note that there is a solder paste on the market (known as solder oil), which is a corrosive thing, is used in industry, is not suitable for electronic production use. There are also commercially available rosin, not the rosin solution we use here.
