Shielding within A High Vacuum Metallising Chamber (RFI, EMC, ESD)
EMC Shielding or Electromagnetic Compatibility is a measure of electrical equipment's ability to neither radiate nor conduct electromagnetic energy, or be susceptible to outside energy sources within its normal operating environment.
Vacuum metalising process is environmentally friendly and metallised parts can be recycled.
We use aluminium for coating within the vacuum chamber, as aluminium is one of the elements that have the highest conductivity apart from gold, silver and copper, gold and silver is too expensive and oxidation takes place uninterruptedly when copper is used, so that considerable corrosion problems arise within a short time.
When aluminum is in contact with the oxygen in the air it forms a stable oxide layer on its surface which is less than 200 A thick. The layer does not interfere with proper electrical contact and gives good protection against corrosion.
When the aluminium coating is first exposed to the atmosphere it is oxidised while in the vacuum chamber. The surfaces electrical resistivity after the initial exposure will remain constant.
The coating thickness for EMI sheilding is measured in microns and is consistent, although in normal commercial coating one could expect approximately ’ ½ micron. Tape testing is used to check adhesion.
There is no cleaning system that can effectively remove silicone mould release agents. The best practice is to make sure that your moulder does not use silicone when moulding parts requiring EMC shielding or coating.