PCB manufacturers requirements for flux

In the welding process, the substances that can purify welding metal and the welding surface and help welding are called flux.

PCB manufacturer physical and chemical properties requirements of flux

① The appearance of the flux should be uniform, transparent, no precipitation or delamination, and no foreign matter.

② Viscosity and density are smaller than molten solder, which can be easily replaced. The density of the flux can be diluted with solvents. The density should be 0.80 ~ 0.95g / cm at 23 ℃. The no-clean flux should be within (100 ± 1.5)% of its nominal density. ,

③ The surface tension is smaller than that of solder, the wetting and expansion speed is faster than that of molten solder, and the expansion rate is greater than 85%.

④ The melting point is lower than that of solder. Before the solder is melted, the flux can fully exert its fluxing effect.

⑤ The content of non-volatile matter should not be greater than 15%, no spatter will occur during welding, no toxic gas and strong irritating odor will be generated.

6.The surface of the residue after welding should be non-adhesive and non-sticky, and the chalk powder on the surface should be easily removed.

⑦ No-clean flux requires less than 2.0% solids, no halide, no residue after welding, no moisture absorption, no corrosion effect, good insulation performance, and insulation resistance greater than 1x10¹¹.

Water-cleaning, semi-water-cleaning and solvent-cleaning fluxes require easy cleaning after soldering.