What is halogen free PCB(HF PCB) substrate

According to jpca-es-01-2003 standard: PCB CCL with chlorine (C1) and bromine (BR) content less than 0.09% wt (weight ratio) is defined as halogen-free copper clad laminate. (at the same time, total CI + br ≤ 0.15% [1500ppm])To get more news about Halogen Free PCB, you can visit pcbmake official website.
2. Why should halogen be banned in PCB
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, flame retardant FR4 substrate, FR4, CEM-3, etc., flame retardant is mostly brominated epoxy resin. In brominated epoxy resin, tetrabromobisphenol A, polybrominated biphenyl, polymerized polybrominated diphenyl ether and polybrominated diphenyl ether are the main blocking fuel for copper clad laminates, which are low cost and compatible with epoxy resin. However, studies by relevant institutions have shown that halogen containing flame retardant materials (polybrominated biphenyl PBB: polybrominated diphenyl ether PBDE) will emit dioxin dioxin (TCDD) and benzfuran (benzfuran) when they are burned on fire. They have a large amount of smoke, bad smell, high toxic gases, carcinogenic, and can not be discharged after ingestion, which is not environmentally friendly and affects human health. Therefore, the EU initiated a ban on PBB and PBDE as flame retardants in electronic information products. According to the same document issued by the Ministry of information industry of China, the electronic information products put into the market shall not contain lead, mercury, hexavalent chromium, polybrominated biphenyls or polybrominated diphenyl ether. Six substances, such as PBB and PBDE, are prohibited by EU law. It is understood that PBB and PBDE are basically not used in the copper clad laminate industry. Bromine flame retardant materials other than PBB and PBDE are mostly used, such as tetrabromobisphenol A, dibromophenol, etc., whose chemical formula is cishizobr4. There are no laws and regulations on this kind of copper clad laminate containing bromine as flame retardant. However, this kind of copper clad laminate containing bromine will release a large amount of toxic gas (brominated type) during combustion or electrical fire. When PCB is used for hot air leveling and component welding, the board will also release a small amount of hydrogen bromide due to the influence of high temperature (> 200); whether dioxins will also be produced is still under evaluation. Therefore, FR4 board containing tetrabromobisphenol A flame retardant is not prohibited by law and can be used, but can not be called halogen free PCB board.
3. Principle of halogen free PCB(HF PCB) substrate
At present, most of halogen free PCB materials are mainly phosphorus and phosphorus nitrogen series. When the phosphorus containing resin is burned, it will decompose into metapolyphosphoric acid, which has strong dehydration property, forms carbonization film on the surface of polymer resin, insulates the burning surface of resin from contacting with air, extinguishes the fire and achieves flame retardant effect. The high polymer resin containing phosphorus and nitrogen compounds produces non combustible gas during combustion, which helps the resin system to be flame retardant.