Manufacturing and Testing Process

The metallization, which acts as an electrode between the consecutive layers of polypropylene film, consists of layers of zinc, silver and aluminium, which are vacuum deposited in controlled environments. The thin metallization layer renders the self-healing property to the film. If, during operation, the base film develops a fault, the cross sectional area at that point increases causing a relative high resistance, and consequently high temperature, which evaporates the metal around the fault and seals it. The metallization repairs or "heals" the "wound" of the film and the capacitor operation is not impaired. The capacitance loss due to the fault in the dielectric layer is negligible.

After winding, the elements are metal sprayed on their ends with high purity soft metals. This operation is performed by specially designed metal spray guns, which melt the metal using electric arc. The molten metal is sprayed on to the capacitor element ends, to which the terminals are fastened, and the element is placed in its container, and finished.

All the materials used in the manufacturing of the capacitors are purchased from world class manufacturers. During manufacture, the capacitors are tested at various stages for verification of the quality and compliance with the specifications.

Testing:
In addition to the type tests, which are carried out on batches, each and every capacitor undergoes testing at four stages during the manufacturing process.

• Automatic Clearing and Sorting:

During metal spraying stage described above, the element is enveloped by thin layer of metal dust, which is later cleaned. In spite of the cleaning, it is necessary to electrically clear the element at low voltage so that the metal dust is evaporated and the capacitor is not short-circuited. Also, it is important to check that the metal spray is conducting properly, and there are no high resistance points. At AMBER, both these operations, and testing/sorting of the elements to check their design and tolerances are carried out on a fully Automatic Capacitor Clearing and Sorting Machine. All bad elements, may they be due to high/low capacitance or dissipation factor, or short circuited, etc., are automatically separated from the good ones.

• High Voltage Testing:
  After the capacitor is produced, high voltage tests are performed on 100% production as per the relevant International Standards.

• Automatic Bridge Checking:
  After the High Voltage tests, 100% production is tested on High Speed Component Testers, where capacitance and dissipation factor is checked for compliance with the tolerance limits. Only after this stage of testing, the capacitor is sent for printing.

• Physical Inspection:
  After printing, and before packing, each and every capacitor is physically examined for aesthetics of printing, terminals, container, etc.