Halogen-free boards are environmentally friendly materials that use a base material that is processed with halogen-free raw materials to produce a PCB circuit board called a halogen-free circuit board. Electronic products contain some specific materials, these materials contain the highest concentration of halogens. To create a halogen-free PCB circuit board for electronics, certain materials need to be replaced or their use on the board needs to be reduced, and the amount of halogens that are to make the circuit also needs to be determined.
What is a Halogen-Free PCB To comply with the requirements of a Halogen Free PCB, the level of halogens contained in the circuit board must not exceed a certain amount, which is measured in parts per million (ppm). What levels are considered halogen-free? The International Electrochemical Commission (IEC) has set the standard at 1,500 ppm total halogens by limiting the use of halogens. chlorine and bromine are both limited to 900 ppm.
Most of the halogen-free sheets are mainly based on phosphorus and phosphorus-nitrogen systems. When phosphorus-containing resins are burned, they are thermally decomposed to produce meta-phosphoric acid, which is highly dehydrating and forms a carbonized film on the surface of the polymer resin, isolating the burning surface of the resin from air and extinguishing the fire to achieve flame retardant effects. Polymer resins containing phosphorus and nitrogen compounds produce non-combustible gases during combustion, which help the resin system to be flame retardant.
What are the characteristics of PCBs made with halogen-free boards?
(1) Insulation: The use of P or N to replace halogen atoms reduces the polarity of the epoxy resin’s molecular bonding segments to a certain extent, thus improving the insulation resistance and resistance to penetration.
(2) Water absorption: Halogen-free sheet due to the nitrogen and phosphorus system of oxygen reduction resin in the N and P of the fox pair of electrons relative to halogen is relatively small, and its hydrogen atoms in the water with the formation of hydrogen bonding rate is lower than that of halogen materials, and thus the material’s water absorption is lower than that of the conventional halogen-based flame retardant materials. For the plate, low water absorption has a certain effect on improving the reliability and stability of the material.
(3) Thermal stability: The content of nitrogen and phosphorus in halogen-free sheets is larger than that of halogen in regular halogen material, so the molecular weight of monomer and Tg value are increased. In the case of heat, the movement of its molecules will be lower than the conventional epoxy resin, and thus the coefficient of thermal expansion of halogen-free materials is relatively small.
Compared with halogenated sheet, halogen-free sheet has more advantages, halogen-free sheet to replace halogenated sheet is also the trend. At present, the world launched a variety of halogen-free solder-resist ink, its performance and ordinary liquid photographic ink are not much different, and the specific operation is also with ordinary ink is the same. Halogen-free PCB circuit boards usually have good heat dissipation reliability, more suitable for lead-free circuits required for high-temperature processes. It also has a low dielectric constant to maintain signal integrity. Therefore the demand for halogen-free PCB circuit boards has been increasing.
What are the advantages of halogen-free PCBs?
(1) They are a less toxic alternative to halogen-filled alternatives. Prioritizing the safety of you, your technicians and those who will be handling the boards is enough to consider using one.
(2) The environmental risk is much lower than equipment containing large quantities of these hazardous chemicals. Especially in areas where best PCB recycling practices are not available, lower halogen content ensures safer disposal. In the age of booming technology, consumers are becoming increasingly aware of toxins in their products, and the applications are virtually limitless-ideally, the devices associated with automotive electronics, cell phones, and other devices we keep in close contact with should be halogen-free.
(3) Reduced toxicity isn’t the only advantage: they also offer performance benefits. These PCBs can often withstand high temperatures, making them ideal for lead-free circuits. Since lead is another compound that most industries try to avoid, you can kill two birds with one stone. Halogen-free PCB insulation may be cost-effective and efficient for disposable electronics.
(4) Since these boards impart a low dielectric constant, it is easier to maintain signal integrity.
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