A lecture on Soldering
Ⅱ. Pb-free Soldering
1. Effect of plumbum use upon environment
First, it’s necessary to explain the background of Pb-free soldering.
Nowadays almost all electric products contain at least a PCB. In the past, eutectic tin solder containing 40% plumbum was used to solder electronic parts onto PCBs. When the electric products got aged and out of use, they would be buried as inflammable garbage.
In recent years, acid rain has brought about new problems: acid rain permeates into soils and dissolves the plumbum on PCBs buried; the polluted water containing the dissolved plumbum flows into underground-water and the under-ground water in turn pollutes rivers and soils.
The polluted water will be used for animals and absorbed by plants and finally the plumbum will find its way into human bodies, doing great harms to human beings, especially to fetuses who may develop nerve system defects, IQ problems and grow-up retardation.
In order to prevent the above mentioned problems from happening, the Pb-free soldering must be employed.