Frequently Asked Questions

What is EMC?

EMC, 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.

What environmental test will vacuum metalized parts meet?

VTI has a variety of plastic resins approved in compliance to UL standard 746C Thermal cycling test for metalized components.

What impact does vacuum metalization on plastics have on the environment?

Virtually none. The vacuum metalization coating process is totally enclosed and all the metalized plastics can be recycled. The aluminum vacuum metalizing process on plastics is environmentally friendly.

Why use aluminum coating?

Aluminum is one of the elements that has the highest conductivity apart from silver and copper. Silver is often too expensive of a solution. As for copper, oxidation takes place uninterruptedly, so that considerable corrosion problems arise within a short time. After being vaporized, aluminum comes in contact with the oxygen in the air and forms a stable oxide layer on its surface which is less than 200 Å thick. The Oxide layer, which does not interfere with proper electrical contact, affords good protection against corrosion.

What about oxidation of the aluminum film over time?

The aluminum coating is oxidized when first exposed to the atmosphere while in the vacuum chamber. The surfaces electrical resistivity after the initial exposure will remain constant.

How thick is the coating?

For EMI and ESD shielding, the coating thickness is very consistent and generally measured in microns. The vacuum metalized surface does not have to compensate for thickness in order to get a good fit between components.

What is the metalized surface resistance on most molded plastics?

Sheet resistance is generally stated in ohms per square. Continuity from point A to B can also be used.

What strength of adhesion can you expect?

On most plastics used today for molding, we use the ASTM D 3359 standard “Measuring Adhesion by Tape Test” method.

How do you pre-clean the plastic parts before metalization?

No cleaning system that we know of can effectively remove silicone mold release. We do have a process that is an integral part of the metalization that will remove light oils, dirt, moisture and other undesirable contaminants. We also have a water-based/mild-chemical cleaning line which will remove heavier contaminants if required. The best practice is to ensure that the molds be clean and free of grease and oils. Some engineered resins can contain a high content of fire retardants or plasticizers that can affect and cause a weak boundary layer between the coating and the substrate.

Do you offer metalized samples?

Yes. Early on in the development phase we know it’s helpful to get prototypes metalized and into the hands of the design engineer without committing to mask tooling. Parts fast tracked can be hand masked as a matter of expediency for early device testing. Contact us for any questions regarding vacuum metalizing samples.

If you have further questions about our vacuum metalization coating process or EMI and ESD shielding, please contact us. We’d welcome the chance to discuss your questions, product design, and EMI Shielding manufacturing needs. 800-482-1941

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