I see water used for some silane depositions and not others. What is the role of water in silane coatings and what is best?
The YES-1224P can do different “water injection” processes depending on the chemicals and process being used. I will tell you the different uses and how each one works. 1. There are two chemical structures we are concerned with. The first is hydroxyl ions (-OH groups) and the second is surface bound water (H2O). The hydroxyl ions are necessary for the reaction of the silane and will form a strong bond on the surface. Surface bound water is weakly bound to the surface and if the silane bonds to it, will form a weak coating on the substrate. When we do a dehydration step in the process, we are trying to remove surface bound water only. Surface bound water evaporates at about 150C (at 1 atmosphere of pressure, it evaporates at a lower temperature with lower pressure). Hydroxyl ions are bound to the surface up to about 450C. The big difference in energy makes it easy to keep hydroxyl ions and remove water. When we perform a plasma surface clean, we may remove both water and hydroxyl ions.
