I. Characteristics of lead and the harm to human body: lead (lead Pb), greyish-white metal, melting point of 327.5 ℃, heated to 400 - 500 ℃ that is, a large number of lead vapour escaping, and in the air

In the air quickly oxidised into lead oxide and condensed into soot and scattered around. At home in the lead and lead war industry is the primary lead mining, lead burning rope and lightweight, battery manufacturing, welding of electronic products and electronic components of the spray lead work and so on. In the above war lead and its compounds primary through the respiratory production and digestive tract invasion of the human body caused by lead poisoning, the human body constitutes damage to health. The U.S. Environmental Protection Agency study created, lead and its compounds are 17 kinds of serious harm to human life and the natural environment of one of the chemical substances. As usual, occupational lead poisoning is a chronic poisoning, which will cause infestation and harm to the human body's nervous system, digestive system and blood system, and its clinical symptoms are

The symptoms are dizziness, fatigue, loss of recollection, nausea, irritability, loss of appetite, abdominal distension and pain, blood deficiency, and substance blockage.

 

       II. The trend of lead-free electronic products: With the advancement of human awareness of their own health and the strengthening of environmental protection consciousness in the world transformer, in order to minimise the lead and other heavy metal

In order to minimise the purification of the environment and the disturbance to human beings caused by heavy metals such as lead, Europe and the United States experimented with lead-free electronic products on 1 July 2006, and China also started to require that all products put on the market be lead-free on 1 July 2006, and that all products put on the market be lead-free.

China also in July 1, 2006 onwards requirements to put on the market of the national key control directory within the electronic housing products do not contain lead content. Is to electronic soldering in the use of solder (solder wire,

solder paste, etc.) used in electronic soldering will gradually abandon the traditional tin-lead alloy and adopt almost pure tin. Just do not contain any impurities of tin is not available, the current international standard for lead-free

The current international standard for lead-free is not aware of the definition of confrontation, foreign normative organisations (ISO) proposal: the lead content of the solder used in electronic assembly should be less than 0.1WT%, but in the lead-free solder is usually in accordance with the requirements of different production works.

Often in accordance with the requirements of different production works, in the tin estimate to participate in some copper and silver and other metal materials to strengthen the tin wire activity of the solder joints of the electrical adjacent to the command.