In terms of the principle of halogen -free base boards, most of the halogen -free materials are mainly phosphorus and phosphorus nitrogen. When the phosphorus resin is burned, it is heated to generate polymer phosphoric acid, which is extremely dehydrated. The surface of the high -molecular resin forms a charcoal film. The resin combustion surface contacts the air to extinguish the fire and achieve the flame retardant effect. Polymer resin containing phosphorus nitride compounds produce non -combustible gases during combustion to help the resin system flame retardant.

　　The halogen-free substrate materials are based on the JPCA-ES-01-2003 standard: the copper-covering plate with a chlorine (C1) and bromine (br) content of less than 0.09 % WT, respectively, is defined as a halogen-free copper plate. (At the same time, the total amount of CI+BR ≤0.15 % [1500ppm]).

　　Why do halogen refers to the halogen elements in the chemical element cycle table, including fluoride (F), chlorine (CL), bromine (br), and iodine (1). At present, flame retardant substrates, FR4, CEM-3, etc., flame retardants are mostly bromide epoxy resin.

　　Related institutions have shown that halogen containing flame retardant materials (polymer polybrine PBB: polymer polyetramide pedazyl pbde), and when the fire is burned, it will release Dioxin, Benzfuran, etc. The amount of smoke is large, the smell is unpleasant, there are high toxic gases, carcinogenic, and cannot be discharged after the human body's intake, which seriously affects health.

　　The characteristics of PCB halogen -free board materials

　　1 Material insulation

　　Because P or N is used to replace halogen atoms, the polarity of the molecular bonding of epoxy resin is reduced to a certain extent, thereby improving the insulation resistance and anti -breakdown ability.

　　2 Material's water absorption

　　Because the fox of N and P in oxygen resin in nitrogen -free plates in nitrogen phosphorus is relatively small than electronics, and the probability of forming hydrogen bonds with hydrogen atoms in water is lower than halogen materials, so the water absorption of its materials is lower than that of its material than Conventional halogen system flame retardant materials. For board, low water absorption has a certain effect on improving the reliability and stability of the material.

　　3 Thermal stability of materials

　　The content of nitrogen and phosphorus in halogen -free plates is greater than the content of halogen of ordinary halogen materials, so its single molecular weight and TG value have increased. In the case of heating, its molecular exercise ability will be lower than the conventional epoxy resin, so the thermal expansion coefficient of halogen -free materials is relatively small.

　　Compared to halogen -free plates, halogen -free plate has more advantages. The replacement of halogen -free plates is also a general trend.