PECVD – POLYMERIZATION - BASE COAT/TOP COAT

This process consists in a monomer (usually HMDSO), injected in the vacuum chamber in gaseous state, that is polymerized by DC or MF glow discharge. The most important parameters of this process are: the vacuum value, the quantity of injected monomer, the applied electric field. The target of polymerization process is giving to the substrates a larger chemical, mechanical, and thermic stability.



The polymerization is targeted to the protection and the antioxidation of the deposited metal, due to this reason is considered an anticorrosion process.

The following picture represents a substrate that undergo an anticorrosion test (humidistat chamber, salina fog, thermic shock).
The right side has been treated, after metal deposition, with polymerization phase, the left side hasn’t undergone this process.
The result clearly show that the polymerization phase guarantees a protection of the substrate by preventing his deterioration that would compromise his use along the time.


The polymerization phase is called “base coat” if is used before the metal deposition and “top coat”
if is used after that process.