>From: IN%"[email protected]" 22-SEP-1996 11:52:29.09
>To: IN%"[email protected]"
>CC:
>Subj: Fwd: RE: Sensor passivation
>Mark, I am very interested in learning more about your message below,
>particularly the method used to deposit an ultrathin parylene coating
by
>means of vacuum deposition. What method of vacuum deposition is used?
>To what temperature is parylene stable? Also, where can we get the
>starting material? Any references to papers on this subject will also
be
>greatly appreciated.
>
Thanks,...........................John.
>John R. Vig
>
>Army Research Lab.
>
>AMSRL-PS-ED
>
>Ft. Monmouth, NJ 07703-5601
John,
First of all let me apologize for misspelling parylene in my first post.
I have to relearn this one every time I use it! Since this is a
question that got a lot of people interested I thought I would post the
answer to the whole group. Parylene is a technology from the 1960's.
There is a very interesting recent article that describes the chemistry
in the Journal of Materials Research 11(7)1842, July 1996. They also
describe how co-polymers can also be deposited using this method--very
clever.
The basic process is as follows: The precursor is a dimer, di-cycloparaxylylene
(or its chlorinated cousin di-cycloparacloroxylyne)
which sublimes at about 120 Celsius. The sublimed vapor is run through
a furnace at 600 Celsius which breaks it into monomers. Then the
monomer vapor is run into a deposition chamber at room temperature.
Polymerization is started by the formation of the trimer. Since the
probability of forming a trimer in the vapor phase is very low,
deposition only happens on the solid surfaces. There are no reaction by
products and the film has excellent throwing power--anyplace that the
vapor can reach is coated.
When you are finished you have a very pure, inert, pinhole free, tough
coating that can be very thin. The trade names of the precursor are
parylene-N and parylene-C. The C has chlorine in it, the N doesn't.
Since at MOXTEK we are interested in low energy x-ray transmission we
usually use the N, but the C is usually preferred as being tougher
stuff. The supplier is called Specialty Coatings [317-244-1200] and can
supply dimer, coating services, coating equipment, application data, and
technical data. We made our own furnace that works nicely.
best regards
mark
Mark W. Lund, PhD
Director >> Soft X-ray Web page http://www.moxtek.com<<
MOXTEK, Inc. *************************************************
Orem UT 84057 **"Soft x-rays in the 21st Century" conference **
801-225-0930 ** 8-11 January 1997, Midway Utah **
FAX 801-221-1121 ** http://volta.byu.edu/xray/info.html **
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