Richard,
As Joyce already pointed out, air, more specifically oxygen, will
terminate the polymerization of the free radical monomer. Those familiar
with Parylene have likely experienced a vacuum leak at some location in
the chamber. The Parylene near the point of the leak, depending on the
severity of the leak, may be opaque, cloudy, or white.
If the substrate outgasses, then there will be a competing effect between
molecules leaving the substrate's surface and the monomer molecules trying
to deposit on the surface. I have not seen any areas completely void of
Parylene, but the area of outgassing may be thinner than other areas that
do not outgas. At some point, the rate of outgassing decreases and is
overcome by the Parylene deposition, which further seals the surface and
further slows the outgassing from the substrate.
I have not experienced anything 'poisoning' the polymerization process.
For the polymerization to not occur, something would have to react with
all the CH2's to prevent the Parylene from growing.
As Doug stated, contaminants usually impact adhesion.
Lamar Young
Specialty Coating Systems, Inc.
7645 Woodland Dr.
Indianapolis, IN 46278
(317) 244-1200 Ext. 276
www.scscoatings.com
From: Douglas Pauls <[log in to unmask]>
To: <[log in to unmask]>
Date: 08/29/2013 10:26 AM
Subject: Re: [TN] Poisoning of Parylene Polymerization
Sent by: TechNet <[log in to unmask]>
Rich,
The one to answer this would probably be Lamar Young at SCS in
Indianapolis. I know that in our Parylene machines, we regularly clean
the pyrolysis tube where the dimer decomposes to the monomer and the
reaction occurs. I don't think contaminants on the board would have much
effect, other than perhaps interfering with adhesion. Do you have much
unused dimer at the end of a deposition run? If so, does it look really
burnt? Is your dimer powder old or has it been stored improperly?
Doug Pauls
From: Richard Kraszewski <[log in to unmask]>
To: <[log in to unmask]>
Date: 08/28/2013 03:54 PM
Subject: [TN] Poisoning of Parylene Polymerization
Sent by: TechNet <[log in to unmask]>
Is anyone aware of any specific contaminants that can poison the
polymerization process in parylene type coatings?
Rich Kraszewski
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
