It is a very common phenomenon to weld electronic components, wires and even nickel sheets of lithium batteries with electric iron. However, we saw some netizens who are keen on DIY complaining on Facebook that he used an electric soldering iron for a long time to solder, and felt that his body began to feel uncomfortable, and his abdomen was a little swollen. Is the solder poisonous? Is it lead poisoning?

　　As a manufacturer of customized lithium batteries for nearly 20 years, SES Power also often uses electric iron to weld BMS and batteries. In fact, regarding these questions of netizens, the key point is to see whether the lead solder wire or lead-free solder is used in the work of the electric soldering iron. In addition, if you often work with soldering, you need to regularly check the level of lead in your blood. If it does not exceed the standard, there will be no problem at all. Generally speaking, if the protection and raw material procurement are carried out according to the standard, the solder will not cause major harm to the human body.

　　A: Solder containing lead cannot be used

　　Lead is a heavy metal. Excessive absorption by the human body can cause lead poisoning, which may affect people's intelligence, nervous system and reproductive system. The alloy of tin and lead is commonly used solder, which has good electrical conductivity of metal and low melting point, so it has been used in welding process for a long time. The toxicity of lead-containing solder comes mainly from lead, which is very easy to hide in fumes.

　　The environmental toxicity of lead to some organisms has been generally confirmed. If the blood lead concentration exceeds 10μg/dl, sensitive biochemical effects will occur. If the blood lead concentration exceeds 60~70μg/dl after long-term exposure, it will cause clinical lead poisoning.

　　When soldering, there will be smoke, which contains an element that is harmful to the body. When working, it is best to wear a mask, but it will still have some impact.

　　B. Using lead-free solder is the right choice

　　Lead-free solder wire does not contain the heavy metal lead. Its main component is tin, but it also contains other metals. With the introduction of the EU ROHS standard, more and more PCB soldering factories have chosen lead-free environmentally friendly ones, and leaded solder wires are gradually being replaced. Lead-free solder paste, lead-free solder wire, and lead-free solder bars are the main products on the market.

　　Lead-free solder wire is environmentally friendly, but lead-free solder wire is also harmful to the human body. The lead content of lead-free solder wire is very low, but it still contains trace amounts of lead after all.

　　The cost of lead-free solder is relatively high, and the fluidity of the metal liquid during soldering is relatively poor, so many low-end factories choose lead-containing tin wires in order to reduce costs and improve efficiency.

　　C: Flux (rosin) is also a potential risk

　　Tin and lead themselves do not produce smell. The smell that many netizens smell when soldering is usually the smell of smoke produced when the flux volatilizes. Generally, it is volatilized when the flux in the tin wire, the rosin-like substance, melts when soldering.

　　The volatilized gas of rosin is also slightly toxic, and this gas is quite unpleasant. In Europe, the protection of welding workers and the protection of the environment have been enforced in the form of legislation, and welding without protective measures is not allowed. In the ISO14000 standard, there are clear regulations on the treatment and protection of pollution generated in the production process.

　　D: How to take precautions when using electric iron to solder:

　　1. Use lead-free tin wire with ROHS logo when soldering components with an electric iron.

　　2. Take precautionary measures such as wearing gloves, masks or gas masks.

　　3. Pay attention to ventilation in the workplace, and the exhaust system is in normal operation.

　　4. Pay attention to cleaning after work, wash your hands and face carefully.

　　5. Try to use PPD welding head so that the temperature can be reached, and less welding oil and rosin can be used to reduce the harm to the body.

　　6. When the soldering oil is smoking, keep your head away as much as possible, and try to hold your breath as much as possible.

　　Soldering with electric iron is an indispensable step for almost all electronic products. It can be said that this step has become an inseparable part of the electronics industry. Even though SES Power is a manufacturer of customized lithium batteries, we also Frequent contact with solder work. Of course, we use 12V100Ah, 24V100Ah, 36V100Ah, and 48V100Ah of square aluminum-shell lithium iron phosphate batteries from EVE, CATL, and BYD. These cells are all laser welded to avoid soldering. These products are used in UPS, data center, energy storage system, photovoltaic power generation, home energy storage, power battery replacement, electric product battery and other occasions. However, in some special occasions, such as harsh industrial environments and low temperature environments, SES Power's lithium batteries that can be used at a normal rate of -40 degrees Celsius are used. These lithium batteries use cylindrical 26650 lithium iron phosphate batteries, so the final use The soldering process of the tin wire is still essential.