Epoxy resin refers to a type of polymer that contains two or more epoxy groups in its molecules. The most prominent feature of epoxy resin is its strong bonding ability, which is the main component of the familiar universal adhesive. In addition, epoxy resin has good chemical resistance, heat resistance, electrical insulation performance, low shrinkage rate, and better mechanical properties than phenolic resin. Epoxy resin can be used as an adhesive for both metallic and non-metallic materials, and is used to package various electronic components.Therefore, the content of impurity ions  in epoxy resin will directly affect the quality of downstream  products, especially  in the electronics  industry. Halogens in FPCB have a significant impact on the insulation performance and service life of circuit boards, so suppliers and users will consider the content of halogens as an important indicator of quality control.