Dip-coating


Dip-coating
A schematic of the continuous dip coating process.

Dip coating is a popular way of creating thin films for research purposes. Uniform films can be applied onto flat or cylindrical substrates. For industrial processes, spin coating is used more often.[1]

Process

The dip coating process can be separated into five stages:[2]

  • Immersion: The substrate is immersed in the solution of the coating material at a constant speed (preferably jitter-free).
  • Start-up: The substrate has remained inside the solution for a while and is starting to be pulled up.
  • Deposition: The thin layer deposits itself on the substrate while it is pulled up. The withdrawing is carried out at a constant speed to avoid any jitters. The speed determines the thickness of the coating (faster withdrawal gives thicker coating material).
  • Drainage: Excess liquid will drain from the surface.
  • Evaporation: The solvent evaporates from the liquid, forming the thin layer. For volatile solvents, such as alcohols, evaporation starts already during the deposition & drainage steps.

In the continuous process, the steps are carried out directly after each other.

References

  1. ^ Scriven, L.E. (1988). "Physics and applications of dip coating and spin coating". Better ceramics through chemistry III. pp. 717–729. 
  2. ^ Rahaman, M.N. (2007). Ceramic Processing. Boca Raton: CRC Press. pp. 242–244. ISBN 0-8493-7285-2.