Lead-free and halogen-free flux paste and preparation method thereof

Lead-free and halogen-free flux paste is composed of, by weight, 35.0-50.0% a solvent, 30.0-40.0% resin, 3.0-8.0% of an active agent, 0.5-1.0% of a stabilizer, 0.5-1.0% of a mold release agent, 1.0-2.0% of an accelerant and 3.0-11.0% of a thixotropic agent. An adopted liquid modified urea rheological agent can be added at any stage of the production process, and through stirring and mixing, solderpaste can have the high rheological performance; the effect that the solder paste has good adhesive force is ensured through maleic resin and modified polyamide resin, by adjusting the proportion ofthe solvent and rosin in flux, the solder paste with a wide viscosity range and the adhesive force being greater than 130 gf can be obtained, the service life of the solder paste is prolonged, and thesolder paste can be stored for nine months at the room temperature; during 0.1mm-thickness silk screen printing, the effect that the mold release performance of BGAs with the diameter being 0.16 mm is good is ensured; and thro