Dip coating process

Dip coating is a widely used deposition technique used to obtain nanometric films. Dip Coating deposition process can be divided into five steps. In the continuous process, the steps are carried out directly after each other:

  • Immersion: The substrate is immersed into a solution of the material to be deposited at a constant immersion rate.
  • Starting: The substrate which has been dipped into the solution for a determinate period of time starts to be pulled up.
  • Deposition: The film is deposited on the substrate while is pulled up. The withdrawal is carried out at a constant rate, avoiding any undesired vibration. The withdrawal speed determines the thickness of the deposited film (a higher speed produces a thicker film).
  • Drainage: The excess of liquid is drained from the surface.
  • Evaporation: The solvent is evaporated from the deposited liquid film, resulting on the coating. For volatile solvents, such as alcohols, the evaporation process starts during the deposition and drainage steps.

The precise control of the immersion speed, the immersion time and the withdrawal speed influences the depth and the characteristics of the resultant coating. This process is carried out with the help of a ND-DC Dip Coater or a ND-R Rotary Dip Coater, in which all these parameters can be easily controlled. In the following image, the dip coating steps are shown. Note that this process can be repeated, and it is usually done like that. Dip coating steps

After the deposition, a drying time is needed or an ageing heat treatment can be applied, in order to reduce the humidity of the film and guarantee its stability [1].

[1] Collinson, M.M., et al., The effects of drying time and relative humidity on the stability of sol–gel derived silicate films in solution. Journal of Electroanalytical Chemistry, 2002. 519(1–2): p. 65-71.

© Nadetech Innovations 2017

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