PCB manufacturersrequirements for flux

In the welding process, the substancesthat can purify weldingmetaland the welding surface and help welding are called flux.

PCB manufacturer physical and chemical properties requirementsof 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.