PCB factory china tells you what are the characteristics of halogen-free sheet?

1. Insulation of materials

Due to the use of P or N to replace the halogen atoms, the polarity of the molecular bond segment of the epoxy resin is reduced to a certain extent, thereby improving the insulation resistance and breakdown resistance.

2. Water absorption of the material

The halogen-free sheet has less N and P pairs of electrons than halogens in the nitrogen-phosphorus-based redox resin, and the probability of forming hydrogen bonds with hydrogen atoms in water is lower than that of halogen materials, so the water absorption of the material is lower than that of conventional halogens. Department of flame retardant materials. For the sheet, low water absorption has a certain influence on improving the reliability and stability of the material.

3. Thermal stability of the material

The content of nitrogen and phosphorus in the halogen-free sheet is greater than that of ordinary halogen-based materials, so its monomer molecular weight and Tg value are increased. In the case of heating, its molecular mobility will be lower than that of conventional epoxy resins, so the thermal expansion coefficient of halogen-free materials is relatively small.

Growing demand for Halogen Free PCBs

Compared with halogen-containing sheets, halogen-free sheets have more advantages, and it is also a general trend to replace halogen-containing sheets with halogen-free sheets. At present, there are many kinds of halogen-free solder resist inks on the market, and their performance is not much different from that of ordinary liquid photosensitive ink, and the specific operation is basically similar to that of ordinary ink.

Halogen-free circuit boards usually have good heat dissipation reliability and are more suitable for high-temperature processes required by lead-free circuits. It also maintains signal integrity due to its low dielectric constant. So the demand for Halogen Free PCB has been increasing.