What is halogen-free PCB substrate

What is halogen-free PCB substrate

According to the JPCA-ES-01-2003 standard: the copper (C1) and bromine (Br) contents are less than 0.09% Wt (weight ratio), which is defined as halogen-free copper clad laminate. To get more news about Halogen Free PCB, you can visit pcbmake official website.

Why ban halogen?

Halogen refers to halogen elements in the periodic table of chemical elements, including fluorine (F), chlorine (CL), bromine (Br), and iodine (1). At present, the flame retardant base material, FR4, CEM-3, etc., the flame retardant is mostly brominated epoxy resin. Among the brominated epoxy resins, tetrabromobisphenol A, polymerized polybrominated biphenyls, polymerized polybrominated biphenyl ethers, and polybrominated diphenyl ethers are the main fuel barriers of copper clad laminates. They have low cost and are compatible with epoxy resins. However, studies by relevant institutions have shown that halogen-containing flame retardant materials (polymerized polybrominated biphenyls PBB: polymerized polybrominated biphenyl ethers PBDE) will emit dioxin (TCDD), benzofuran (Benzfuran), etc. The amount of smoke is large, the smell is unpleasant, the highly toxic gas is carcinogenic, and cannot be discharged after ingestion. It is not environmentally friendly and affects human health. Therefore, the EU initiated a ban on the use of PBB and PBDE as flame retardants in electronic information products. The same document from the Ministry of Information Industry of China requires that by July 1, 2006, electronic information products put on the market must not contain lead, mercury, hexavalent chromium, polymerized polybrominated biphenyls or polymerized polybrominated biphenyl ethers.

The laws of the European Union prohibit 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, and most of them use bromine flame retardant materials other than PBB and PBDE, such as tetrabromo Bisphenol A, dibromophenol, etc., its chemical formula is CISHIZOBr4. This kind of copper clad laminate containing bromine as a flame retardant is not regulated by any laws and regulations, but this type of bromine-containing copper clad laminate will emit a large amount of toxic gases (bromide type) when burning or electrical fires, and the amount of smoke is large ; When the PCB is used for hot air leveling and component welding, the plate is affected by high temperature ( 200), and it will also release a trace of hydrogen bromide; whether it will also produce dioxins is still under evaluation. Therefore, FR4 sheets containing tetrabromobisphenol A flame retardant are not currently prohibited by law and can be used, but cannot be called halogen-free sheets.
For now, most of the halogen-free materials are mainly phosphorous and phosphorous nitrogen. Phosphorus-containing resin decomposes by heating to produce meta-polyphosphoric acid, which has strong dehydration properties, which forms a carbonized film on the surface of the polymer resin, and isolates the resin combustion surface from contact with air to extinguish the fire and achieve a flame retardant effect. The polymer resin containing phosphorus and nitrogen compounds generates non-combustible gas when it is burnt, which helps the flame retardant of the resin system.