A lecture on Soldering
5. The work-parts which can not be soldered
It can be felt by touching with your fingers that wire soldering tin is a kind of very soft metal. Since the soldering tin could be broken easily, it is not supposed to be used for welding the machine parts that require high mechanic strength. Tin solder is mainly used in welding just for acquiring electricity conductivity, instead of for the parts under stress or vibration.
Tin solder cannot be used for welding parts of stainless steel, aluminum, steel or iron. If it is used for these metals, it will be broken easily by a modest pull. Welding on these parts requires special electroplating or special welding flux or using special welding techniques.