>From: IN%"jvig@arl.mil" 22-SEP-1996 11:52:29.09 >To: IN%"lundm@xray.byu.edu" >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 ** lundm@xray.byu.edu ************************************************* "Let me commend a great truth to you which has been one of the supports of my life: 'The Gods send threads for a web begun.' Andrew Carnegie