Why do PCB circuit boards need halogen-free requirements when detecting halogen elements in electronic components?

Date：2022-04-18 15:08:21Views：1490

What does the meaning of halogen-free and halogen-free plates in PCB plates mean? To put it simply, halogen plates are not environmentally friendly, while halogen-free plates are relatively environmentally friendly. The simplest way is to slice them and analyze them. Halogen is a non-metallic element of group VII a, which includes five elements: Fluorine -, chlorine, bromine, iodine and astatine. Astatine is a radioactive element, and halogen is usually referred to as fluorine, chlorine, bromine and iodine.

Halogen compounds are often used as flame retardants: PBB, PBDE, TBBP-A, PCB, hexabromododecane, tribromophenol, short chain chlorinated paraffin, etc. they are used in electronic components and materials, product shells, plastics, etc. This kind of flame retardant can not be recycled, and will release harmful substances in the process of combustion and heating, threatening human health, the environment and future generations. Halogen free requirements: the content of bromine and chlorine is less than 900ppm respectively, (bromine + chlorine) is less than 1500ppm. Halogen and halogen-free cannot be simply distinguished. XRF analysis should be used, but the analysis is fast. One sample can be analyzed in an average of 2 ~ 3 minutes.

What is halogen-free substrate? According to jpca-es-01-2003 standard: copper clad laminates with chlorine (C1) and bromine (BR) contents less than 0.09% wt (weight ratio) respectively are defined as halogen-free copper clad laminates. (meanwhile, the total amount of CI + br ≤ 0.15% [1500ppm])

What is halogen-free substrate?

According to jpca-es-01-2003 standard: copper clad laminates with chlorine (C1) and bromine (BR) contents less than 0.09% wt (weight ratio) respectively are defined as halogen-free copper clad laminates. (meanwhile, the total amount of CI + br ≤ 0.15% [1500ppm])

Why ban halogen?

Halogen refers to the halogen group elements in the periodic table of chemical elements, including fluorine (f), chlorine (CL), bromine (BR) and iodine (1). At present, the flame retardant base materials, such as FR4 and CEM-3, are mostly brominated epoxy resin. Among brominated epoxy resins, tetrabromobisphenol A, polymerized polybrominated biphenyl, polymerized polybrominated diphenyl ether, polybrominated diphenyl ether is the main barrier fuel of copper clad laminate, which has low cost and is compatible with epoxy resin. However, the research of relevant institutions shows that halogen containing flame retardant materials (polybrominated biphenyls PBB: polybrominated diphenyl ether PBDE) will release dioxin (TCDD) and benzfuran (benzfuran) when they are abandoned and burned. They have large smoke volume, bad smell, highly toxic gas and cause cancer. They cannot be discharged after ingestion, which is not environmental friendly and affects human health. Therefore, the EU initiated to prohibit the use of PBB and PBDE as flame retardants in electronic information products. The same document of the Ministry of information industry of China requires that electronic information products put into the market shall not contain substances such as lead, mercury, hexavalent chromium, polybrominated biphenyls or polybrominated diphenyl ether from July 1, 2006.

The EU law prohibits the use of six substances such as PBB and PBDE. It is understood that PBB and PBDE are basically no longer used in the copper clad laminate industry. Bromine flame retardant materials other than PBB and PBDE are mostly used, such as tetrabromobisphenol A and dibromophenol. Their chemical molecular formula is cishizobr4. This kind of copper clad laminate containing bromine as flame retardant is not regulated by any laws and regulations, but this kind of copper clad laminate containing bromine will release a large amount of toxic gas (brominated type) and produce a large amount of smoke in case of combustion or electrical fire; When PCB is used for hot air leveling and component welding, the plate will also release a small amount of hydrogen bromide under the influence of high temperature (> 200); Whether it will also produce dioxins is still under evaluation. Therefore, FR4 plate containing tetrabromobisphenol A flame retardant is not prohibited by law and can still be used, but it cannot be called halogen-free plate.