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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?
UL 746C Thermal Cycling Test
What impact does vacuum metalization have on
the environment?
Virtually none. The process is totally enclosed and all the metalized
part can be recycled. The process of Vacuum Metallizing is environmentally
friendly.
Why use
aluminum coating?
Aluminum is one of the elements that have the highest conductivity
apart from silver and copper. Silver is too expensive. As for copper,
oxidation takes place uninterruptedly, so that considerable corrosion
problems arise within a short time. After being vaporized, aluminum
in contact with the oxygen in the air forms a stable oxide layer
on its surface which is less than 200 Å thick. The 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 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?
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 contaminates if required.
The best practice is to insure 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.
Can we hand mask and metalize samples
of your part?
Yes. Early on in the development phase we know it’s helpful
to get prototypes metalized without committing to mask tooling.
Parts can be hand masked as a matter of expediency for early device
testing.
If you have further questions, 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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