As a typical and most active non-metallic element, halogen elements mostly exist as halogen compounds in nature. Fluorine (f), chlorine (CL), bromine (BR), iodine (I) and astatine (at), referred to as halogen for short. As astatine is a radioactive element, people often say halogen only refers to fluorine (f), chlorine (CL), bromine (BR) and iodine (I). Halogen is widely used in flame retardants, refrigerants, solvents, organic chemical raw materials, pesticides, pesticides, bleaches, wool degreasing, etc. Most of the halogen compounds used in industry are organic halogen compounds, and many organic halogen compounds are listed as chemicals harmful to human beings and the environment, which are prohibited or limited, and are the key pollutants controlled by countries all over the world.
At present, halogen compounds used in products are mainly flame retardants, such as PBB, PBDE, TBBP-A, PCB, hexabromododecane, tribromophenol and short chain chlorinated paraffin; Ozone destroying substances used as refrigerants and thermal insulation materials, such as CFCs, HCFCs, HFCS, fire extinguishing agents, cleaners, pesticides, bleaches, wool degreasing agents, etc.
Halogen compounds are widely used in electronic industry. For example, chlorinated paraffin can be used as plasticizer of plastic materials, and dichlorodifluoromethane can be used as foaming agent in ABS, PS, PVC, PU and other plastics. However, halogen compounds are most widely used as flame retardants. Common halogen flame retardants include bromine flame retardants such as PBB, PBDE, TBBP-A and hbcdd, and chlorine flame retardants such as short chain chlorinated paraffin and PCB. The use of flame retardants can play a flame retardant effect, and halogen flame retardants have less impact on the inherent physical and mechanical properties of the flame retardant substrate. However, the use of halogenated flame retardants also has disadvantages: in case of fire, the incomplete combustion of halogenated flame retardants will produce a large number of carcinogens; Moreover, the materials using halogen flame retardants will produce a large amount of smoke and toxic corrosive gases during combustion, which will hinder fire fighting and personnel evacuation and corrode instruments and equipment.
Regulatory requirements for halogen detection
(1) EU 2011 / 65 / EU restricted substances: brominated flame retardants
(2) Restricted substances of the global Montreal Protocol: five chlorofluorocarbons (CFCs) and three halons
(3) Substances restricted by the Stockholm Convention of 151 countries and organizations: organochlorine pesticides, hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).
(4) IEC regulations for printed board materials iec61249-2-21. Maximum limit: chlorine, bromine, total halogen
Which products need halogen testing
Resin in various plastic parts (substrate, mold, flux, underfill, etc.);
Printed circuit board and printed circuit board assembly;
Welding flux residue;
Resin in cables, connectors, sockets and external wiring;
Resins in mechanical plastics (masks, fans, etc.).
