Halogen elements include fluorine (Fluorine), chlorine (Chlorine), bromine (Bromine), iodine (Iodine) and strontium (Astatine). Among them, Astatine is a radioactive element. The halogens commonly referred to are fluorine, chlorine, bromine and iodine. Halogen-free control mainly involves Chlorine and Bromine.
Halogen compounds have received widespread attention due to the following hazards:
1, some halogen compounds are harmful to the environment and human body: such as halogen-containing POPs;
2, the halogen-containing organic solvent is ozone depleting substance (ODS)
3, halogen-containing plastics will release hydrogen halide (HCl, HBr, etc.) when exposed to high temperatures, forming acid mist in the air in contact with water vapor;
4, when halogen-containing plastics burn, produce dioxins, which are high-accumulation, high-lasting carcinogens;
5, when halogen-containing plastics burn, a large amount of smoke will be generated, resulting in decreased visibility and affecting the identification of escape routes.
At present, halogen-containing plastics, especially chlorine-containing and bromine-containing plastics, are widely used in the electrical and electronic industry. The halogen in plastics includes PVC, plasticizers, flame retardants, etc., and includes other forms of halogens such as toners, pigments and other organic halogens. Among the common flame retardants, Chlorinated Flame Retardants (CFRs) and Brominated Flame Retardants (BFRs) are the most common. There are hundreds of kinds of BFRs, and the price is low, the flame retardant effect is good, and the cost performance is very high, so it has been widely applied and recognized. Common flame retardants include organic flame retardants and inorganic flame retardants, organic flame retardants include CFRs, BFRs, phosphorus flame retardants, etc.; and inorganic flame retardants include: boron flame retardants, aluminum hydroxide, hydrogen Magnesium oxide, red phosphorus, ammonium polyphosphate, cerium oxide and molybdenum compounds, etc., have low flame retardancy and large addition amount, and far less widely used CFRs and BFRs. If the application of BFRs is completely banned now, it is difficult to find a better alternative to BFRs in a short time.
At the same time, halogen-containing plastics face great difficulties in recycling and disposal, so more and more customers are paying attention to halogen-free.
For halogen-free requirements, IEC 61249-2-21:2003 specifies the printed circuit board. The specific requirements are: bromine < 0.09% (900 ppm), chlorine < 0.09% (900 ppm), and the sum of halogens is<1500 ppm.
The detection methods are:
IPC-TM-650 220.127.116.11; BS EN 14582:2007 standard;
IEC 61249:2003 Section 2.21 (IEC 61189:2006-3);
JY/T 020: 1996 General Principles of Ion Chromatography;
GB/T9872:1998 Determination of halogen in rubber;
ASTM D 4327: 2003 Common anion determination in water, etc.
Halogen-free is a trend. Although there is no uniform regulatory requirement at present, it will be relevant in the future. Therefore, as a company should reduce the use of halogen-containing materials and find alternative materials.