According to jpa-es-01-2003 standard, copper clad plate with chlorine (C1) and bromine (Br) content less than 0.09% Wt(weight ratio) is defined as halogen-free copper clad plate.To get more news about Halogen Free PCB, you can visit pcbmake official website.
1.2 why do we ban halogen
Halogen refers to the halogen group of elements in the periodic table of chemical elements, including fluorine (F), chlorine (CL), bromine (Br), and iodine (1).At present, the flame retardant substrate, FR4, cem-3, etc., flame retardants are mostly brominated epoxy resin.Brominated epoxy resin, tetrabromobisphenol A, polybrominated biphenyl, polybrominated diphenyl ether, polybrominated diphenyl ether is the main resistance fuel of copper clad plate, its cost is low, compatible with epoxy resin.But research shows that institutional containing halogen flame retardant materials (polymerization polybrominated biphenyl PBB: polymerization polybrominated diphenyl ether PBDE), waste burning, emit two well English (dioxin dioxin TCDD), benzene furan (Benzfuran), such as large amount of smoke, smelled, highly toxic gas, carcinogenic, unable to discharge after intake, not environmental protection, affect human body health.Therefore, the European Union 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 electronic information products put on the market by July 1, 2006, must not contain substances such as lead, mercury, hexavalent chromium, polymerized polybrominated biphenyls or polymerized polybrominated biphenylene ether.
The eu law prohibits the use of PBB and PBDE and other six substances, it is known that PBB and PBDE in the copper coated plate industry has been basically not in use, more use is in addition to PBB and PBDE bromine flame retardant materials, such as tetrabromobisphenol A, dibromophenol, etc., the chemical formula is CISHIZOBr4.There are no laws and regulations on this kind of brominated flame retardant copper clad plate, but this kind of brominated copper clad plate, when burning or electrical fire, will release a large number of toxic gas (brominated type), the amount of smoke;When PCB is welded with hot air and even components, the plate is subjected to high temperature (200) impact, will also release trace of hydrogen bromide;Whether dioxins are also produced is still being assessed.Therefore, FR4 plates containing tetrabromobisphenol A flame retardants are not currently prohibited by law and can still be used, but cannot be called halogen free plates.
This paper discusses the processing characteristics and experiences of halogen-free PCB.
1.3 principle of halogen-free substrate
At present, most of the halogen-free materials are mainly phosphorous and phosphorous nitrogen systems.Phosphorous resin in the combustion, thermal decomposition to produce polyphosphoric acid, extremely strong dehydrating, the surface of the polymer resin to form a carbonized film, isolation of the resin burning surface and air contact, so that fire extinguishing, flame retardant effect.The polymer resin containing phosphorus and nitrogen compounds produces non-combustible gas when burning, which helps the resin system flame retardant.
2 characteristics of halogen-free plate
2.1 insulation of materials
Since P or N are used to replace halogen atoms, the polarity of molecular bond segment of epoxy resin is reduced to a certain extent, thereby improving the insulation resistance and resistance to penetration.
2.2 water absorption of the material
As the N and P fox in N and P deoxidizing resins of nitrogen and phosphorus series have fewer electrons than halogens, the probability of forming hydrogen bond with hydrogen atoms in water is lower than that of halogen materials, so the absorbency of the materials is lower than that of conventional halogen flame retardant materials.For the plate, the low water absorption has a certain effect on improving the reliability and stability of the material.
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