Lead-free environmentally friendly solder wire
uses lead-free solder instead of traditional tin-lead eutectic solder, which makes the process of lead-free environmentally friendly solder wire have significantly different characteristics. First, the temperature of the welding process is significantly increased, and the process window is sharply reduced. The currently commonly used lead-free solders are tin-silver-copper and tin-copper series alloys. The melting points of these two combined alloys are around 217°C and 227°C respectively, which are higher than the melting point of 183°C of traditional tin-lead eutectic solder. 34~44°C. However, the maximum temperature in actual use is 20~30°C or more higher than that of the traditional process.
Secondly, since the wettability of lead-free solder used in lead-free environmentally friendly solder wire is significantly lower than that of tin-lead solder, in order to obtain a good solder joint that meets the standard, it must be ensured that the component leads and PCB pads are soldered. Better solderability. Also, because the traditional tin-lead solderability coating must be replaced, more pure tin coating is used instead, so it is really difficult to maintain better solderability of lead-free environmentally friendly solder wire without causing other problems. This problem is the same for lead-free solder bar.