Substrate-induced deposition of carbon black particles from aqueous dispersion on gelatin-modified surface

In the process of substrate-induced deposition of carbon black, a printed wiring board (PWB) surface is first covered with a gelatin film. The subsequent immersion of such substrates into a deposit-able dispersion leads to deposition of dispersed particles on the surface of the substrate. Current studies show that an essential point in the successful preparation of deposit-able dispersions is control of surfactant and salt concentrations, both of which have a decisive influence on particle deposition. On one hand, the dispersion must be stable. For this purpose surfactants are used. On the other hand, the dispersion must be near the point where deposition can occur. This point is controlled by the appropriate addition of a salt, which screens the electric field of the surfaces and allows particles to approach to shorter distances during their Brownian motion. Atomic force microscope (AFM) has been used to measure distance dependence of the forces between microscopic-size glass spheres coated with gelatin and a solid surface covered with carbon black in the presence of aqueous solution.