
Frequently Asked Questions
General Information
Do you have a representative in my area? In order to
provide you with the most timely service and most accurate information,
all inquiries are handled directly by our in-house staff. If
your situation requires a visit to your facility, we will gladly
arrange for one of our staff to meet with you.
Do you have what I need in stock? We carry a large
inventory, so it is possible that we have what you are looking
for in our warehouse. If not, our lead times are significantly
shorter than is common for the industry.
What if I don't see what I need on your web site? Ask
us! Chances are that we can help, even if you don't see the item
on our site.
What is the best way to send a print to MTS? We can
accept prints by mail, fax, or e-mail. We accept all cad formats.
To speed your quotation, please ensure that prints are properly
and completely toleranced.
When will I receive my quotation? We understand the
rapid pace of business these days. Our goal is to return a quotation
to you within 24 hours of receiving your request. You can help
speed this process by tolerancing prints, indicating purchase
quantities, and specifying material compositions in your inquiry.
Vacuum Metallizing
What is vacuum metallizing? Vacuum evaporation? Vacuum
deposition? All of these terms can be used to describe the
same process, with vacuum metallizing being a more specific case.
Within the confines of a chamber which has had most of the air
removed, metals or other materials are heated until they vaporize.
This vapor travels about the chamber and condenses on surfaces
within the chamber, forming a thin film.
Why is the deposition performed under vacuum? Two reasons
- to lower the boiling point of the material to be deposited
and to allow the subsequent vapor to travel about the chamber
without interference from air molecules.
How great a vacuum is needed? Typically metallizing
is performed under a vacuum of at least 10E-4 (.0001) torr. One
torr is also known as one millimeter of mercury. Atmospheric
pressure is 760 torr.
How is the evaporation material heated to boiling?
In the most simple case, a wire or sheet of metal is used as
both a container and heater for the material to be evaporated.
By running a current through this metal, enough heat is generated
to cause vaporization of the evaporation material. Tungsten,
molybdenum, or tantalum are the usual choices because they have
melting points higher than most evaporation materials.
Are there other techniques for vacuum deposition? Yes.
Besides using resistance heated thermal evaporation sources,
methods such as electron beam, cathodic arc, and sputtering can
be used. These methods have a much higher capital equipment cost.
They may be appropriate, however, for materials which would decompose
or degenerate upon heating.
What kind of materials can be evaporated? Many metals,
compounds, chemicals, and alloys can be evaporated and/or deposited.
The material will dictate which of the techniques listed above
should be used. Please contact us for details on specific materials.
What materials are commonly vacuum coated? Plastic
is probably the most common material coated. Often this is to
enhance the appearance of a plastic part or to increase its reflectivity.
A metallic coating may also be used to reduce electromagnetic
or radio frequency interference in electrical or electronic devices
with plastic housings. Lenses can be coated to improve performance,
integrated circuits can be created, film for food packaging is
often metallized to improve its barrier properties.
Can you describe the characteristics of the deposited film?
The deposited film is typically very thin, and composed of small
platelets formed when the vapor hits the substrate. Films are
usually in the neighborhood of 1000 angstroms thick. Films may
contain small pinholes. Films are generally fragile and should
be protected with a topcoat. There are exceptions to this, like
SiO films. Films take on the character of the substrate underneath.
Reflective films must have a smooth substrate. Film thickness
can affect opacity, color and reflectivity.
 
You can reach us by e-mail at:
mts@tungsten.com
Midwest Tungsten Service
540 Executive Drive
Willowbrook, IL 60527 |
Toll Free: 1-800-626-0226
Phone: 1-630-325-1001
Fax: 1-630-325-3571 |
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