M seires is the normal model for keboard circuit printing. And HF series is halogen free.
HF series are one-component electrical conductive ink, with halogen free. They are specifically formulated as a screen applied silver conductive coating for printing conductive tracks onto flexible substrates, such as polyester, polyimide, indium tin oxide substrates.
HF series are suitable for use on hand, semi-automatic or fully automatic screen printing machines. Thermal curing induces chemical cross-linking to form stable films suitable for reflow, offering good chemical & electrical properties for many electronic applications.