Abstract: Disclosed is an aqueous alloy plating solution for surface treatment of a modular PCB. The plating solution comprises 1-30 wt % of an organic acid having at least one sulfonic acid group (—SO3H), 0.1-20 wt % of a complexing agent, 0.1-15 wt % of a thio-compound having at least one —S—, 0.05-5 wt % of a water soluble gold compound, 0.001-1 wt % of a water soluble silver compound and 0.1-10 wt % of a sequestering agent, based upon the weight of the plating solution. According to this invention, all plating properties required for the modular PCB are obtained through a single plating process, instead of the conventional double plating process.

Abstract: Disclosed are a conversion coating composition for use in the surface treatment of a PCB and a conversion coating method using the same. The composition comprises 0.1-30 vol % of sulfuric acid; 0.1-15 vol % of hydrogen peroxide; 0.01-10 wt % of an organic acid; 0.1-30 wt % of a nitrogen compound; 0.01-10 wt % of an organic silicate and/or organic titanate; and 0.1-20 wt % of a film forming auxiliary, 0.1-30 wt % of an etching rate controller, 0.1-20 wt % of a reaction promoter and/or 0.1-20 g/l of a stabilizer. This composition is applied to a PCB at 10-60° C. for 1-10 min. The conversion coating film is superb in adhesive strength, acid resistance, and adhesion and can be formed with ease.