| The equipment used (mechanism, droplet formation rate), and the resist (viscosity, surface tension) mainly determine the distribution of the droplet diameters.The quantities temperature, relative velocity, and air solvent saturation, as well as the solvent composition and concentration determine the evaporation rate for each droplet as a function of the droplet surface. This surface concentration again depends on the temperature- and solvent concentration dependant diffusion constant of solvent from the droplet bulk to its surface.The quantities wetting, edge coverage, and homogeneity, which strongly impact on spray coating performance, depend on the initial coverage of the droplets from the atomized spray, the resist adhesion to the substrate, the resist surface tension, and its viscosity. Therefore, beside the chemical and physical resist properties, the atomized spray formation mechanism (distribution of the droplet sizes), the flight of the droplets to the substrate (evaporation), and the solvent evaporation out of the growing/grown resist film (time dependant surface tension and viscosity) determine the spray coating result with respect to homogeneous, smooth, and closed films. Therefore, we recommend TI PRIME adhesion promoter which also improves the substrate wetting/coverage of the growing film even at very low viscosities. |
Request: Equipment manufacturers for spray-coating
Optimum Substrate Pre-Treatment